The present application generally relates to apparatus and methods for coupling shape memory alloy (SMA) actuator wires to an actuator or actuating component, and in particular to a tool for manufacturing or assembling parts of an actuating module.

There are many types of apparatus in which it is desirable to provide positional control of a movable element. SMA actuator wire is advantageous as an actuator (or part of an actuator/actuating component) because of its high energy density, which means that an actuator comprising SMA actuator wire that is required to apply a particular force can be of a relatively small size.

An example is the use of SMA actuator wire to provide haptics feedback in consumer electronics devices, such as laptops and smartphones, to give users of the devices some feedback indicating that they have successfully pressed a button on the device. The ever-decreasing thickness of portable computing devices, and the increasing display screen size, means that there is relatively little free space within a smartphone for haptic buttons. An alternative example type of apparatus for which SMA actuator wire is used to provide positional control of a movable element is a camera. For example, to achieve focussing, zooming, or shake correction, an actuating component may be used to drive movement of a camera lens element or an image sensor along the optical axis (or primary axis) of the camera and/or in a plane orthogonal to the optical axis (or primary axis). In miniature cameras, such as those provided within smartphones, the camera lens element is small and therefore, the actuating component may need to be compact (particularly given space restrictions within smartphones). Alternatively, SMA actuator wires may also be used to provide positional control of a movable element in e.g. pumps, valves, medical devices, 3D sensing systems, augmented reality (AR) display systems. In these examples, the actuating component must be capable of providing precise actuation over a correspondingly small range of movement. Due to the small size of the moveable element, and the high precision actuation required, the SMA actuator wires may need to be coupled to the actuating component carefully and precisely.

In a first approach of the present techniques, there is provided a guide mechanism for guiding a plurality of shape memory alloy (SMA) actuator wires into a fixing mechanism of an actuating module, the guide mechanism comprising: at least one guide element for separately guiding the plurality of SMA wires towards the fixing mechanism; a holder for holding the plurality of SMA wires adjacent a fixing mechanism, wherein the holder is moveable between a first position in which the plurality of SMA wires are adjacent the fixing mechanism and a second position in which the plurality of SMA wires are within the fixing mechanism; and an insertion mechanism for moving the moveable holder between the first and second positions.

In a second approach of the present techniques, there is provided an apparatus for assembling an actuating module comprising a plurality of shape memory alloy (SMA) actuator wires, the apparatus comprising the guide mechanism described above for guiding a plurality of shape memory alloy (SMA) actuator wires into a crimp of an actuating module; and a crimping mechanism for closing the crimp to couple the plurality of SMA actuator wires to the actuating module.

In a third approach of the present techniques, there is provided a method for assembling an actuating module comprising a plurality of shape memory alloy (SMA) actuator wires, the method comprising: aligning, using an alignment mechanism, a crimp of the actuating module with a crimping mechanism; guiding, using a guide mechanism, the plurality of SMA wires towards the crimp; moving, using the guide mechanism, the plurality of SMA wires into the crimp; closing, using the crimping mechanism, the crimp to couple the plurality of SMA wires to the actuating module; and forwarding, using the alignment mechanism, the actuating module; wherein when guiding and moving the plurality of SMA wires, a spacing between each wire is maintained.

The present techniques also provide a non-transitory data carrier carrying processor control code to implement any of the methods or processes described herein.

Implementations of the present techniques will now be described, by way of example only, with reference to the accompanying drawings, in which :

Figure la is a cross-sectional view of an actuator assembly;

Figure lb is a plan underside view of the actuator assembly of Figure la with some components removed for clarity; Figure 2 shows a block diagram of an apparatus for assembling an actuating module comprising at least one shape memory alloy (SMA) actuator wire;

Figure 3 shows a perspective side view of an apparatus for assembling an actuating module comprising at least one SMA actuator wire;

Figures 4a and 4b are respective side views of an unspooling and tensioning part of the apparatus of Figure 3;

Figure 4c is a cutaway cross-section of a detail of the unspooling and tensioning part of Figure 4a;

Figure 5a is a perspective view of part of a guide mechanism of the apparatus of Figure 3;

Figure 5b is an enlarged view of part of the guide mechanism of Figure 5a;

Figure 5c is a cross-section view of part of the guide mechanism of Figure 5a;

Figures 6a to 6c are alternative components for the guide mechanism of Figure 5a;

Figures 7a, 7b and 7c are plan views showing different arrangements for inserting wires into an actuating module;

Figures 7d, 7e and 7f are side views showing different arrangements for inserting wires into an actuating module;

Figures 8a and 8b are perspective and cross-sectional views of a forwarding mechanism of an alignment mechanism;

Figure 8c shows the variation in radius of each cam within the forwarding mechanism of Figure 8a;

Figures 8d plots the variation with rotation angle of radius and acceleration at a fixed point for each cam within the forwarding mechanism of Figure 8a;

Figure 8e is a perspective close-up view of an upper surface of the alignment mechanism;

Figure 8f is a cross-section view shows pins which form part of the alignment mechanism;

Figures 8g, 8h and 8i are side views of the alignment mechanism with some elements removed for clarity;

Figure 8j plots the variation in the travel way against an adjustment of the height H of the cam follower;

Figure 8k is a schematic illustration of part of the circumference of a forwarding cam in the alignment mechanism of Figure 8a; Figure 9a is a perspective view of a crimping mechanism of the apparatus of Figure 3;

Figure 9b is a perspective underside view of punches in the crimping mechanism of Figure 9a;

Figure 9c is a perspective plans view of anvils in the crimping mechanism of Figure 9a;

Figures 9d and 9e are two different side views with elements removed to show the internal detail of parts of the crimping mechanism of Figure 9a;

Figures 10a and 10b are plan views of a strip showing four variations of crimp closing using the crimping mechanism of Figure 9a;

Figures Ila and 11b are cross-sectional views show initial and crimping positions of a retaining member of the crimping mechanism of Figure 9a;

Figures 12a is a side view of the slack addition mechanism;

Figure 12b is a cross-sectional view of an upper section of the slack addition mechanism of Figure 12a;

Figures 12c and 12d are cross-sectional views of a lower section of the slack addition mechanism of Figure 12a in a position in which minimum and maximum slack respectively is added;

Figures 12e and 12f are plan views of a strip show two alternative arrangements for positioning the moveable slack adding members of the slack addition mechanism of Figure 12a relative to the punches;

Figures 13a and 13b are perspective views of two arrangements of crimps to which the apparatus may be adapted;

Figure 14 shows a flow chart of example steps for assembling an actuating module comprising at least one SMA actuator wire;

Figure 15a is a cross-sectional view of part of the alignment mechanism of Figure 8a at a first position in the cycle;

Figure 15b is a perspective view of parts of the guide mechanism which cooperate with the alignment mechanism in a first position;

Figure 15c is a cross-sectional view of the co-operating parts of Figure 15b in a second position;

Figure 15d is a cross-sectional view of the guide mechanism in Figure 15b;

Figure 15e is a perspective view of part of the guide mechanism;

Figure 15f and 15g are cross-sectional views of part of the alignment mechanism of Figure 8a at a second and a third position in the cycle, respectively; Figure 15h shows the timing cycle of the alignment mechanism of Figure

8a;

Figure 16a is a perspective view of an alternative guide mechanism for guiding sets of wires towards and into the crimps;

Figure 16b is a schematic view of the guide mechanism of Figure 16a illustrating movement of the various components; and

Figure 16c is a schematic view of the guide mechanism of Figure 16a illustrating the location of the sets of the wires.

Broadly speaking, embodiments of the present techniques provide apparatuses and methods for accurate positioning and coupling of a shape memory alloy (SMA) actuator wire to an actuator or actuating component (or module). The apparatus may be manually-operated (i.e. by a human user), partly manually-operated and partly automated, or fully automated. The apparatus may comprise different mechanisms which may be operated independently.

For example, there may be a guide mechanism for guiding a plurality of shape memory alloy (SMA) actuator wires into a fixing mechanism of an actuating module, the guide mechanism comprising: at least one guide element for separately guiding the plurality of SMA wires towards the fixing mechanism; a holder for holding the plurality of SMA wires adjacent a fixing mechanism, wherein the holder is moveable between a first position in which the plurality of SMA wires are adjacent the fixing mechanism and a second position in which the plurality of SMA wires are within the fixing mechanism; and an insertion mechanism for moving the moveable holder between the first and second positions.

By separately guiding the plurality of SMA wires towards the fixing mechanism, a spacing may be maintained between each wire to minimise tangling. For example, the at least one guide element may comprise at least one pulley comprising a plurality of grooves with one groove for each SMA wire. By running each SMA wire in a groove, the wires are separated. Alternatively, the at least one guide element may comprise a plurality of pulleys with one pulley for each SMA wire. A mix of multi-groove and individual pulleys may be used to provide the required number of guide elements to guide each SMA wire from its source (e.g. a spool) to the fixing mechanism.

The holder may comprise a plurality of capillary tubes with one capillary tube for each SMA wire. Each tube may have a similar diameter to the SMA wire. Alternatively, there may be a single capillary tube housing the plurality of SMA wires. Alternatively, the holder may comprise a needle having a plurality of slots with one slot for each SMA wire or a plurality of needles, one for each SMA wire. The holder(s) help to maintain the spacing between the SMA wires as the SMA wires are positioned in the fixing mechanism. Alternatively, the holder may comprise a pulley. The pulley for a holder may be relatively small compared to a pulley used as the at least one guide element.

The insertion mechanism may comprise a moveable support to which the holder is mounted, the moveable support comprising a member which is biased in a first position in which the plurality of SMA wires are adjacent a fixing mechanism; and a lever which is moveable between a raised position and a lowered position wherein in the lowered position the lever engages the member to move the moveable support to a second position in which the plurality of SMA wires are within the fixing mechanism. The member may comprise a cam follower for engaging the lever as the lever is moved from the raised position to the lower position. The guide mechanism may further comprise a return spring (or similar biasing mechanism) which is attached to the member to bias the member in the first position. The lever may be adjustable to change an initial point of contact between the lever and the member. Similarly, the movement of the member may be adjustable via an adjustable end stop. Each of the lever and the member may be rotatable about a hinge point.

The at least one guide element may be positioned over the holder. In this way, the plurality of wires may be guided from a source which is above the fixing mechanism (e.g. crimp) into which the wires are to be inserted. The at least one guide element may be positioned below the holder. In this way, the plurality of wires may be guided from a source which is below the fixing mechanism (e.g. crimp).

The at least one guide element may comprise at least one first guide element guiding a first set of SMA wires towards a first fixing mechanism and at least one second guide element guiding a second set of SMA wires towards a second fixing mechanism. Similarly, the holder may comprise a first holder for holding the first set of SMA wires and a second holder for holding the second set of SMA wires. Each of the first and second fixing mechanisms may be positioned on either side of the actuating module. In this arrangement, the insertion mechanism may comprise a first moveable support to which the first holder is mounted and a second moveable support to which the second holder is mounted.

The first and second moveable supports may be moveable simultaneously or separately. For example, there may be a first lever and a second lever which is moveable between a raised position and a lowered position wherein in the lowered position the first lever moves the first moveable support to a second position in which the first set of SMA wires are within the first fixing mechanism and the second lever moves the second moveable support to a second position in which the second set of SMA wires are within the second fixing mechanism.

The insertion mechanism may comprise a third moveable support adjacent the first and second fixing mechanism and the third moveable support is moveable in a direction which is perpendicular to the movement of the first and second moveable holders. For example, the moveable supports may be sliders. The first and second moveable holders may be moveable in a generally horizontal motion and the third moveable support may be moveable in a generally vertical motion. The first and second holders may be positioned so that the first and second sets of wires cross each other between the first and second holders and the third moveable support. In this way, a weaving action may be used to introduce the wires into the fixing mechanisms.

The at least one first guide element and the at least one second guide element may be spaced further apart than the first and second holders. This may allow the wires to be fed into the fixing mechanisms from outside. Alternatively, the at least one first guide element and the at least one second guide element may be spaced closer together than the first and second holders. This may allow the wires to be fed into the fixing mechanisms from inside.

Each of the at least one guide elements may comprise a plurality of separate guide elements, e.g. a plurality of pulleys. Each of the separate guide elements may hold all of the wires. Alternatively, the at least one guide element may comprise a plurality of separate guide elements, each one of the separate guide elements guiding a single wire from the plurality of wires. For example, the at least one first guide element may comprise a plurality of separate guide elements, one for each wire in the first set of wires and the at least one second guide element may comprise a plurality of separate guide elements, one for each wire in the second set of wires The fixing mechanism may typically be a crimp which is closable by a crimping mechanism. Alternatively, the fixing mechanism may be any suitable mechanism for fixing the SMA wires to the actuating module, e.g. bonding, spot welding, gluing, soldering, or similar.

The guide mechanism may be incorporated in an apparatus for assembling an actuating module comprising a plurality of shape memory alloy (SMA) actuator wires. The apparatus may thus comprise the guide mechanism described above for guiding a plurality of shape memory alloy (SMA) actuator wires into a crimp of an actuating module; and a crimping mechanism for closing the crimp to couple the plurality of SMA actuator wires to the actuating module. The insertion mechanism may comprise a moveable support to which the holder is mounted, wherein movement of the crimping mechanism to close the crimp causes the moveable support to move the holder from the first position to the second position. For example, the insertion mechanism may comprise a lever which is mounted to the crimping mechanism to move the moveable support as the crimping mechanism is moved between a raised position and a lowered position.

The apparatus may further comprise a slack addition mechanism for adding slack to the SMA actuator wire before the crimping mechanism closes the crimp. The slack addition mechanism may comprise a moveable slack adding member which is received in a corresponding recess. The slack addition mechanism may comprise a pin which engages an adjustable end stop to control the amount of slack which is added.

In the arrangement in which there are crimps (or other fixing mechanisms) on either side of the actuating module, the slack addition mechanism may be configured to separately add slack to the first set of SMA wires and the second set of SMA wires. The crimping mechanism may be configured to simultaneously close the first and second crimps. The crimping mechanism may comprise a plurality of punches and anvils; one for each crimp which is to be closed in a crimping action. The crimping mechanism may be configured to close multiple crimps in a single movement. The multiple crimps may be on a single actuating module or may be on different actuating modules.

The apparatus may further comprise an alignment mechanism for aligning and forwarding a component of the actuating module to which the plurality of SMA wires are to be coupled. When forwarding the component, acceleration may be as low as possible to prevent stress to any wires already coupled to the component. The alignment mechanism may comprise a positioning pin for engagement with the component when closing the or each crimp and a forwarding pin for engagement with the component to forward the component to a next location for crimping. The alignment mechanism may comprise a positioning pin cam which is rotatable to move the positioning pin, a forwarding pin cam which is rotatable to move the forwarding pin and a forwarding cam which is rotatable to forward the component.

The alignment mechanism may be used in the apparatus described above or as a separate component for another apparatus. We also describe an alignment mechanism for aligning and forwarding a component of an actuating module, the component comprising a plurality of fixing mechanisms to which at least one wire is to be coupled, the alignment mechanism comprising a forwarding mechanism for forwarding the component to a fixing position in which at least one first fixing mechanism is to be coupled to the at least one wire; and a positioning mechanism for engagement with the component when the component is in the fixing position to maintain the at least one of the fixing mechanisms in the fixing position when coupling the at least one wire to the at least one first fixing mechanism; wherein, after the at least one wire has been coupled to the at least one first fixing mechanism, the forwarding mechanism is configured to forward the component to a subsequent fixing position in which at least one second fixing mechanism is to be coupled to the at least one wire and wherein the forwarding mechanism is configured to forward the component with minimal acceleration.

The positioning mechanism may comprise a positioning pin which is moveable between a first raised position in which the positioning pin engages the component and a second lowered position in which the positioning pin is not in contact with the component. The positioning mechanism may comprise a return spring which biases the positioning pin in the second position. The positioning mechanism may comprise a positioning pin cam which is rotatable to move the positioning pin between the first and second positions. The positioning mechanism may comprise a lever which contacts the positioning pin at one end and is attached to a cam follower at the opposed end whereby rotation of the positioning pin cam causes the lever to pivot and move the positioning pin from the second position to the first position. The forwarding mechanism may comprise a forwarding pin which is moveable between a first raised position in which the forwarding pin engages the component and a second lowered position in which the forwarding pin is not in contact with the component. The forwarding mechanism may comprise a return spring which biases the forwarding pin in the second position. The forwarding mechanism may comprise a forwarding pin cam which is rotatable to move the forwarding pin between the first and second positions. The forwarding mechanism may comprise a first lever which is attached to a cam follower at the one end and a second lever which is in contact with the forwarding pin, whereby rotation of the forward pin cam causes the second lever to pivot and move the first lever which moves the forwarding pin from the second position to the first position.

The forwarding mechanism may comprise a forwarding cam which is rotatable to forward the component when the forwarding pin is in the first position. The forwarding mechanism may comprise a sliding assembly which supports the component during forwarding. The forwarding mechanism may comprise a lever which contacts the sliding assembly at one end and is attached to a cam follower at the opposed end whereby rotation of the forwarding cam causes the lever to pivot and move the sliding assembly.

The forwarding cam may be larger than the forwarding pin cam and the positioning pin cam. Each of the forwarding cam, the forwarding pin cam and the positioning pin cam may be mounted on one shaft. The forwarding cam, the forwarding pin cam and the positioning pin cam may be rotatable together to move the forwarding pin from the second position to the first position at generally the same time as the positioning pin is moved from the first position to the second position and vice versa. The forwarding cam, the forwarding pin cam and the positioning pin cam may be rotatable together to move the forwarding pin from the second position to the first position, forward the component when the forwarding pin is in the first position and move the forwarding pin from the first position to the second position when the component is in the subsequent fixing position.

The alignment mechanism described above may be incorporated in an apparatus. We also describe an apparatus for assembling an actuating module comprising a plurality of shape memory alloy (SMA) actuator wires, the apparatus comprising: an alignment mechanism as described above for aligning and forwarding a component of an actuating module; and a closing mechanism for closing the fixing mechanism to couple the at least one SMA actuator wire to the at least one fixing mechanism when the component is aligned in a fixing position.

The apparatus may further comprise a slack addition mechanism for adding slack to the SMA actuator wire before the closing mechanism closes the fixing mechanism. The apparatus may further comprise a tensioning mechanism for tensioning the at least one SMA actuator wire.

The apparatus may further comprise a guide mechanism for guiding the at least one SMA actuator wire into the at least one fixing mechanism. The guide mechanism may be described as above. For example, the guide mechanism may comprise at least one guide element for guiding the at least one SMA wire towards the fixing mechanism; a holder for holding the at least one SMA wire adjacent the fixing mechanism, wherein the holder is moveable between a first position in which the at least one SMA wire are adjacent the fixing mechanism and a second position in which the at least one SMA wire are within the fixing mechanism; and an insertion mechanism for moving the moveable holder between the first and second positions.

The holder may comprise a plurality of capillary tubes with one capillary tube for each SMA wire or a single capillary tube for all the wires. The insertion mechanism may comprise a moveable support to which the holder is mounted, the moveable support comprising a member which is biased in a first position in which the at least one SMA wire is adjacent a fixing mechanism; and a lever which is moveable between a raised position and a lowered position wherein in the lowered position the lever engages the member to move the moveable support to a second position in which the at least one SMA wire is within the fixing mechanism.

The at least one guide element may comprise at least one first guide element guiding a first set of SMA wires towards a first fixing mechanism and at least one second guide element guiding a second set of SMA wires towards a second fixing mechanism; and the holder comprises a first holder for holding the first set of SMA wires and a second holder for holding the second set of SMA wires.

The closing mechanism may be a crimping mechanism comprising a plurality of punches and anvils and the fixing mechanism is a crimp. The crimping mechanism may be configured to simultaneously close at least two crimps. Merely to assist understanding of how SMA actuator wires may be used to provide precise actuation of a moveable element, an example of an actuating module that uses SMA actuator wires is now described. The example is described in more detail in GB1906916.0, the contents of which are herein incorporated by reference. Figures la and lb show an actuator assembly 110 which may be provided within a cavity below a button. Movement of the button in a first direction, e.g. as a result of the user activating the button, may be detected by a force exerted on a force sensor or in any other appropriate way by a sensor. The sensor may be coupled to control circuitry (not shown), and the sensor may be configured to communicate with the control circuity when the button press is detected. The detection by the sensor of a user pressing the button causes the haptic feedback to be generated and applied via the actuator assembly 110. The sensor may be any suitable sensor which is able to detect a button press may be used. Examples include force resistors, strain gauges, capacitive sensors, electroactive polymers, switches, inductive sensors and piezoelectric films.

The actuator assembly comprises a housing (not shown for clarity of viewing the internal components) which may be formed from any suitable material, e.g. steel. The housing is covered by a resilient layer 114 which may be a spring or flexure. The overall size of the housing may be small, e.g. 12mm by 3.5mm by 1.9mm. Within the housing, there is a first wedge layer 122 and a second wedge layer 124 between which there are ball bearings 130a, 130c. A spacer 128 separates the second wedge layer 124 from a crimp layer 126 which engages with an inner surface of the housing via ball bearings 132a, 132c. There is also a chassis 134 supporting various layers.

Figure lb shows the detail of the crimp layer 126 which comprises an elongate portion 170 and two pairs of crimps with each pair having a crimp located at opposed ends of the crimp layer 126. A first pair of crimps 138a, 138b is mechanically and electrically connected to a first set of SMA wires 142 and a second pair of crimps 140a, 140b is mechanically and electrically connected to a second set of SMA wires 144. In this arrangement, each set comprises three wires but it will be appreciated that this is merely exemplary and a different number of wires may be included in each set. There is thus at least one SMA wire, and may be at least two SMA wires (one on either edge) in the actuator assembly. A first crimp 138a, 140a in each pair of crimps is connected to one end of the elongate portion 170 of the crimp layer 126 and may be termed a moveable crimp. A second crimp 138b, 140b in each pair of crimps is connected to the static chassis 134 and may be termed a static crimp.

Electrical connections 146, 148 extend from the static crimps and project out through a side wall of the housing as shown in Figure la. The whole crimp layer 126, or the portion comprising the crimps, is formed of a material that is suitable for coupling to (e.g. crimping) an SMA actuator wire. For example, the crimp layer may be made from a suitable metallic material, e.g. stainless steel which is gold plated in the crimps and on the electrical connections to improve the electrical connections. As explained in more detail below, the crimp layer 126 may be formed in a frame and detached from the frame before or during the assembly process leaving detach tabs 172.

The elongate portion of the crimp layer 126 comprises a first pair of bearing apertures within which the pair of ball bearings 132c, 132d which are adjacent the static crimps are located. At the opposed end of the elongate portion of the crimp layer 126 there is a second pair of bearing apertures within which the pair of ball bearings 132a, 132b which are nearest the moveable crimps are located. The ball bearings 132a, 132b, 132c, 134d facilitate movement of the elongate portion. In this arrangement, there are two pairs of ball bearings, one at each opposed end of the elongate portion but it will be appreciated that other arrangements may be used. Projections 136a, 136b act as an electrical insulation wall between the SMA wires and the live metal parts and are received in elongate indentations which extend partially along opposed sides of the elongate portion.

The elongate portion of the crimp layer 126 also comprises a pair of wedge apertures for receiving the projections 150a, 150b of the second wedge layer. As shown in Figure la, the projections 150a, 150b of the second wedge layer are slightly sub-flush with the crimp layer 126 and do not extend beyond the crimp layer 126 because of the thickness of the crimp layer and spacer layer which is related to the diameter of the bearings.

The elongate portion of the crimp layer 126 extends towards but is not connected to the first end portion 152 on the chassis 134. The elongate portion is a moveable element of the actuator assembly and moves relative to the chassis 134 which may be described as a static element. Thus, the moveable crimps are termed moveable because they are attached to the moveable element. Similarly, the static crimps are termed static because they are attached to the static element. The moveable crimps move relative to the static crimps. There is a second end portion 178 of the chassis at the opposed end to the first end portion 152. The second end portion comprises a raised stub 180 which has a surface which engages with a force concentrator (which may be floating). Generally speaking, if an SMA actuator wire is stretched too far (i.e. a certain tension is exceeded), the SMA actuator wire may weaken or become damaged, or even break. This may happen for example in a drop or other extreme event. Therefore, the second end portion 178 may act as an endstop to restrict the movement of the crimp layer and the second wedge layer so that the at least one SMA actuator wire does not overstretch.

Movement of the crimp layer causes movement of the second wedge layer which is transferred to the first wedge layer (moveable element). The movement of the moveable element may for example be between 10 pm to 500 pm, more preferably between 10pm to 100 pm and may be in a first direction, which as indicated in the Figures is vertical. More generally, the first direction may be a direction that is perpendicular to the external surface of the resilient layer 114, as indicated by arrow A in Figure la. The elongate portion of the crimp layer and the second wedge layer (optionally with the spacer) may be considered to form an intermediate moveable element which moves in a second direction which is different to the first direction. The second direction may be a direction that is substantially parallel to the external surface of the resilient layer 114, as indicated by arrow B in Figure la. The first direction and the second direction may be orthogonal. Movement of the intermediate moveable element in the second direction may cause movement of the moveable element and hence a button in the first direction. That is, movement of the intermediate moveable element may cause the button to be moved in such a way that a haptic effect/sensation is delivered to a user touching the button. The concept of moving intermediate moveable element in one direction to cause movement of the moveable element (and hence button) in another direction may be implemented in a number of ways.

The resilient layer 114 may perform two functions. The resilient layer may function as a return spring which 'resets' the actuator. Thus, the resilient layer 114 may comprise an element which opposes the force of the at least one SMA actuator wire 142, 144. The resilient layer may function as a mechanism that constrains the motion of the first wedge layer to be along the first direction (i.e. perpendicular to the external surface of the resilient layer 114, as indicated by arrow A in Figure la). The resilient layer 114 may be most compliant along the first direction, less compliant in a first orthogonal direction corresponding to the width of the resilient layer, and least compliant in a second orthogonal direction corresponding to the length of the resilient layer. During actuation, the resilient layer 114 may be loaded by the SMA actuator wire(s) along the first direction and along the second orthogonal direction. However, movement of the resilient layer 114 along the second orthogonal direction may be insignificant because the resilient layer is stiffest (least compliant) in that direction. The two functions of the resilient layer 114 may be independent of each other. It will be understood that the return spring is only one non-limiting example. In alternative embodiments, a return spring may not be used. Instead, the force of a user's finger on the button may be sufficient to oppose the contraction of the at least one SMA actuator wire 142, 144.

Multiple wires may typically provide faster cooling than a single wire which provides the same force and has a similar overall cross-section to the cross-section of the multiple wires. Performance of such an actuator is dependent on the balance of the multiple wires. To achieve maximum performance, ideally all the wires will have identical performance when powered. As will be understood by a person of skill in the art, assembling the example SMA actuation apparatus shown in Figures la and lb may be difficult, because of the small size of the actuation apparatus, and the precise arrangement of the SMA wires. Accordingly, the present techniques provide a precision manufacturing tool and process for assembling an SMA actuation apparatus. As explained below, the mechanisms in the apparatus provide the ability to reliably and quickly insert all the wires with minimal operations and close the crimps.

Turning to Figure 2, this shows a block diagram of an apparatus 200 for assembling an actuating module comprising at least one shape memory alloy (SMA) actuator wire. The apparatus 200 may enable accurate positioning and coupling of a shape memory alloy (SMA) actuator wire to an actuator or actuating component. The apparatus 200 may be manually-operated, partly manually- operated and partly automated, or fully automated.

Generally speaking, the actuating module comprises a component to which an SMA actuator wire is to be coupled. The actuating module may comprise: a support structure, for example, for supporting a moveable component; a moveable platform; an integrated circuit chip or processor for controlling the movement of the actuating module; the moveable element; etc. The term "component to which an SMA actuator wire is to be coupled" is used herein to mean any component of the actuating module to which the SMA wire is to be coupled. The term is used herein to mean that both ends of the SMA actuator wire may be coupled to the same component of the actuating module, or that each end of the SMA actuator wire may be coupled to different components of the actuating module. The term is also used to cover the possibility that both ends of the SMA wire are coupled to a fret having crimps, where the fret is coupled to the actuating module.

The apparatus 200 may comprise a tensioning mechanism 202 for tensioning an SMA actuator wire. The SMA actuator wire may be provided from a spool of wire of known tension. The spools of wire may comprise wire stretched to a known tension, sufficient to prevent further stretching during handling. Additional tensioning may also be provided by the tensioning mechanism 202. This also means that once the wire is coupled to the actuator (e.g. via crimps), the wire is taut, as required for controllable actuator operation.

A guide mechanism 204 may be provided for guiding an SMA actuator wire into position such that it can be coupled to the correct part of the actuator or actuating component. Similarly, an alignment mechanism 206 may be provided for guiding the part of the actuator or actuating component to which the SMA wire is to be connected into the correct position. Each end of a length of SMA actuator wire is coupled to different points on the actuator/actuating component, as shown in the example of Figures la and lb. Accordingly, the guide mechanism 204 and alignment mechanism 206 may co-operate to guide an SMA actuator wire such that a portion of the SMA actuator wire is guided towards and positioned at one coupling site on the actuator, and another portion of the SMA actuator wire is guided towards and positioned at another coupling site on the actuator. In embodiments, each end of an SMA actuator wire may be coupled to the actuator via a crimp or crimping element, which securely fastens the end of the SMA actuator wire to the actuator, while also ensuring a mechanical and electrical connection is made between the SMA actuator wire and the actuator. Thus, the guide mechanism 204 may guide the SMA actuator wire towards one or more crimps, which is provided at a coupling site on the actuator and the alignment mechanism 206 may be used to move a set of crimps to the correct location for insertion of the wires. The apparatus may comprise a crimping mechanism 208 to close each crimp/crimping element after the SMA actuator wire is positioned in the pair of crimps. The crimping mechanism 208 may comprise any suitable mechanism to close each crimp. The crimping mechanism 208 may comprise components which are aligned with the coupling sites/location of the crimps on the actuator, such that when the crimping process takes place, the components are in the correct position to close the crimps without touching (and thereby, potentially damaging) any other parts of the actuator. The crimping mechanism 208 may be moveable, e.g. rotatable to assist in ensuring the correct alignment. It will be understood that the crimping operation only takes place once the SMA actuator wire has been guided into the correct position.

It may be useful to deliberately add some slack to the SMA actuator wire before it is coupled to the actuator, such that once the wire is coupled to the actuator, the SMA wire is slack rather than taut. It has been found that such slack wires may provide a greater actuator stroke than that of a similar actuator made with taut wires. This is because a longer SMA wire provides greater stroke, so using a longer wire may generally be advantageous, and because the wire from the spool is already under tension, such that it is difficult to stretch the wire any further during operation of the actuator. Thus, in embodiments, the apparatus/ tool 200 may comprise a slack addition mechanism 210. The slack addition mechanism 210 may be arranged to provide a specific, controllable amount of slack or additional length of actuator wire between the coupling sites/crimps.

As mentioned above, SMA actuator wires are often used to move small components, such as a lens in a miniature camera of a smartphone. As the components of an actuator may need to be as small as possible, this may result in the SMA actuator wire being located very close to other components of the actuator, camera or smartphone, especially metallic components. If the SMA actuator wire contacts a metal surface that is at a different potential to the SMA actuator wire, then a short circuit may occur. This can cause local heating and/or a spark on the surface of the wire, which can lead to melting and damage of the SMA wire. The SMA wire may become weakened, which may lead to reduced performance or fractures that cause breakage of the wire. Accordingly, it may be desirable to coat or wrap a core of SMA material with a layer of electrically insulating material, to provide an SMA actuator wire that is sufficiently electrically and thermally insulated. In embodiments, the SMA actuator wire may be formed of a core of SMA material that is coated with an electrically insulating layer. The insulating layer may have a thickness in the range of 0.3|jm to 10pm (for example of the order of 1pm).

The SMA actuator wire may be formed such that the electrically insulating layer is provided along the entire length of the core SMA material. However, achieving good mechanical and electrical contact between the SMA actuator wire and the crimps of the actuator may be hindered by the presence of a relatively thick layer of electrically insulating material. The mechanical action of closing the jaws of the crimp during assembly may not be sufficient to break the electrically insulating layer and thereby, make good contact with the core of SMA material beneath. Thus, in embodiments, the apparatus /tool 200 may comprise an insulation removal module 212, for selectively removing at least one portion of an electrically insulating coating or layer of the SMA actuator wire. The insulation removal module may be arranged to remove portions of the electrically insulating coating of an SMA actuator wire, and in particular, remove portions of the electrically insulating coating corresponding to the portions of SMA actuator wire that are to be coupled to the actuator. The electrically insulating coating may be selectively removed using any suitable technique, such as mechanical abrasion, chemical removal, laser or plasma ablation, or melting of the coating by heating (e.g. using a laser).

Some or all of the components described above may be incorporated in the same apparatus. Alternatively, one or more of the components described above may be incorporated in a known machine to improve its performance. For example, the guide mechanism 204 may be used as an add-on component in other machines.

Figure 3 shows a perspective view of an example apparatus 300 for assembling an actuating module comprising at least one SMA actuator wire. As mentioned above, the apparatus 300 may enable accurate positioning and coupling of a shape memory alloy (SMA) actuator wire to an actuator or actuating component. The apparatus 300 may be manually-operated, partly manually- operated and partly automated, or fully automated. The example apparatus 300 shown in Figure 3 may be considered to comprise two parts or segments, as indicated by the dashed boxes. The segment on the left hand side of the apparatus 300 as shown in Figure 3 may be considered to be an unspooling and tensioning station 301 which comprises the tensioning module 302, while the segment on the right hand side may be considered to be a crimping station 303. The segment of the apparatus 300 on the right hand side may comprise the guide mechanism 304, the alignment mechanism 306, the crimping mechanism 308 and/or a slack addition mechanism (shown in detail below).

Each of the modules in the crimping station may be attached to a single main structural assembly 320 which comprises a back structure 322 and a die tool set comprising a die tool top 324 and a die tool base 326. The die tool base 326 may be static in a vertical direction, while the die tool top 324 may be moveable in a vertical direction on die set bearings 328. The die tool set may comprise a handle or lever 312 for moving the die tool top 324. Moving the lever 312 (in the direction indicated by the arrow, i.e. rotating the handle down about a horizontal axis) may cause the die tool top 324 to move in a vertical direction. Thus, the die tool top 324 can be moved closer to the die tool base 326 by operation of lever 312. The travel of the die tool top may be approximately 40mm.

The die tool base 326 is supported on a structural support 330 which extends generally at right angles to the back structure 322 (which is generally vertically mounted). A rail assembly 332 which forms part of the alignment mechanism 306 as explained in more detail below is mounted on the structural support 330. The rail assembly 332 supports and aligns the actuator or actuating component with the wires. In this arrangement, the rail assembly 332 comprises a groove 334 within which the actuator or actuating component (or strip thereof) travels during the manufacturing process.

Figures 4a, 4b and 4c show the detail of the unspooling and tensioning part 302. In this arrangement, the unspooling and tensioning part 302 is set up to provide six separate SMA wires - three for each side of the crimp portion. The unspooling and tensioning part 302 comprises a spool sub assembly comprising three spools 402 which are located on a first side of the assembly to provide the three wires which will be held in a first pair of crimps and three spools 404 which are located on an opposed side to provide the three wires which will be held in a second pair of crimps. It will be appreciated that if a different number of wires are required, the number of spools may be adjusted (e.g. increased or reduced) and/or wire may only be drawn from the number of spools necessary.

The assembly may comprise a first support plate 422 to which the first set of spools 402 are mounted and a second support plate 424 which is spaced from the first support plate 422 and to which the second set of spools 404 are mounted. As shown in Figure 4c, each one of the spools 402 on the first support plate 422 may be coupled to a spool 404 on the second support plate 424 by a shaft 420. Each shaft 420 may be connected to a pulley 428 and associated timing belt which sits within the space between the first and second support plates and which allows the rotation of the shaft and hence the spool to be controlled to unspool the wires. In this arrangement, there is a handle 426 which is manually turned to drive the pulleys and timing belts but it will be appreciated that this may be automated. There may also be flanged bearings and spacers to facilitate motion of the spools. There may also be idler subassemblies to provide tension in the timing belt.

The unspooling and tensioning part 302 also incorporates a tensioning module 202 which comprises at least one tensioning unit mounted on a support. The number of tensioning units may match the number of spools to keep each wire from each spool separate from one another to avoid tangling. In this arrangement, the tensioning module 202 comprises three tensioning units 408 which are located on a first side and three tensioning units 410 which are located on the opposed side. In this arrangement, each of the tensioning units 408, 410 comprises a plurality of (e.g. three) tensioning pulleys 412. Each wire is routed over each of the plurality of tensioning pulleys 411, 412 and tension may be created by weighting at least one of the tensioning pulleys. For example, 30 g of weight may be attached to the hanging pulley 411.

Once tensioned, each wire is then routed through one or more guide pulleys towards the other part of the apparatus. In this arrangement, there is a guide pulley 414 at the base of each tensioning unit 408, 410. There are also as additional guide pulleys 416, 418 which are spaced away from the tensioning units. As shown more clearly in Figure 5a, the additional guide pulleys 416 for the tensioning units on the first side are mounted on the support, e.g. at the base of the support as shown. The additional guide pulleys 418 for the tensioning units on the opposed side are mounted on a pulley mount 520 which is spaced from the tensioning module and is under a guide plate of the next part of the apparatus. Each of the guide pulleys 414, 416, 418 may be considered to be a guide element which forms part of the guide mechanism. The angle of each of the guide pulleys 414, 416, 418 may be adjustable to change the angle of the wire to feed the wire correctly towards the other part of the apparatus.

The guide mechanism may further comprise at least one multi-groove pulley 516a, 516b, 516c, 518a, 518b, 518c which may be considered to be guide elements of the guide mechanism. The number of grooves in each multi-groove pulley may match the number of wires, e.g. three in this arrangement. A wire from each of the guide pulleys 416 is fed into a first multi-groove pulley 516a and similarly, a wire from each of the guide pulleys 418 is fed into a first multi-groove pulley 518a. Each of the first multi-groove pulleys 516a, 518a is located below the guide plate of the next part of the apparatus. The next two multi-groove pulleys 516b, 518b are located within the second part of the apparatus and are above the guide plate. The final two pulleys 516c, 518c are shown in Figure 5b. Each pulley may be set an appropriate angle to ensure each wire is guided into the crimps correctly.

Figure 5b shows the detail of the final part of the guide mechanism which comprises a plurality of capillary tubes 520, 522. The wires are fed from one final pulley 516c into a corresponding set of tubes 520 and from the other final pulley 518c into a corresponding set of tubes 522. These final pulleys 516c, 518c may also be multi-groove pulleys so that there is a longer length of wires which are not touching one another and thus the risk of tangling and/or snagging is reduced. However, using a single pulley as a final pulley and then diverging into the capillary tubes may have a low risk of tangling/snagging because of the space constraints. The number of tubes may match the number of wires, e.g. three in this arrangement. The use of the capillary tubes allows the wires to be brought very close to the crimping position and held in place during the crimp closing. As explained in more detail below, the tubes may be moved to move the wire into the crimp before closing. Once the wires are crimped in position, the tubes are returned to their original position. The tubes may be termed a holder for the SMA wires.

The tubes may be removable for easier wire set-up, for example in this arrangement there are screws 530 which may be removed to allow the block 532 to which the tubes are mounted to be removed together with the tubes. The positioning has to be very accurate and tolerance may be as small as +/-28pm and thus care needs to be taken to ensure that the tubes are correctly positioned. For example, as shown more clearly in Figure 5c, the height of the tubes may be adjusted by including one or more shim washers 534. The use of a countersunk head screw 530 in the middle of a dowel within the block 532 may improve positioning accuracy but other fixing mechanisms may also be used. The use of multi-groove pulleys and capillary tubes allows the wires to be maintained separately throughout the guide mechanism and hence reduces the risk of any tangling or crossing of the wires. As an alternative to multi-groove, multiple pulleys, one for each wire, may be used if there is sufficient space. However, it will be appreciated that one or more of the multi-groove pulleys may be replaced with a single groove pulley when the risk of tangling is not high and otherwise separation of the wires is not required. Similarly, the plurality of capillary tubes may be replaced with a single capillary tube which is wide enough to accommodate all the wires.

Alternative holders for guiding the wire into the correct location may also be used, including pulleys, needles, pins, thread guides or similar. For example, Figures 6a and 6b shows schematic illustrations of two arrangements of needles which may be used instead of the capillary tubes. In Figure 6a, a single needle 602 is used to replace each set of capillary tubes. The needle 602 comprises a plurality of eyelets 604 and a single wire passes through each eyelet 604. The number of eyelets matches the number of wires to be placed in a single crimp which in this arrangement is three. Figure 6b shows an arrangement in which a plurality of needles 606, each having a single eyelet 608 is used. The number of needles matches the number of wires to be placed in a single crimp which in this arrangement is three. Like the capillary tubes, the needles may be moveable to facilitate movement of the wires into the crimps. Figure 6c shows an alternative in which a pulley 650 is used as the holder. The pulley 650 is mounted on a moveable member 652 which moves in the direction of the arrow shown to place the wires in the crimp.

The crimps may be pre-formed in a strip 700 to be fed into the apparatus for accurate positioning and coupling of the SMA wire. The strip 700 is preferably made from a thin sheet metal which may be punched, photo-etched or otherwise manufactured in the desired pattern and features required for crimping and the other functions associated with attaching them to the rest of the actuator and electrical circuit. The strip can be any length according to the handling requirements, production environment and production volumes. For example, the strip could be provided on a reel which may be substantially longer, e.g. several kilometres, and the handling may be performed mechanically using an alignment mechanism as described below. An example of such a strip 700 is shown in Figures 7a to 7c which comprises a plurality of crimp layers 726 such as those shown in Figures la and lb. The strip 700 may also be termed a coupon and the terms may be used interchangeable. Each crimp layer 726 may be within one of a plurality of frames 702 of the strip. Within each frame 702, there are four crimps 750a, 752a, 750b, 752b which may be considered to form two pairs of crimps with each pair being joined by a plurality (in this arrangement three) of SMA wires. Once the crimp layer is attached to the wires, a first set of SMA wires is held in a first pair of crimps 750a, 752a and a second set of SMA wires is held in a second pair of crimps 750b, 752b.

Each frame 702 has one or more indexing features in the form of apertures 704, 708 to assist in alignment as described below. In this arrangement, each frame 702 has an aperture 704, 708 on opposed edges of the frame 702 with one aperture 708 located closer to a corner of the frame than the other aperture 704. As explained in more detail below, a first aperture 704 may be a positioning (or indexing) aperture for accurately aligning the crimp layer before the crimps are closed. A second aperture 708 may be a forwarding aperture for advancing the strip 700 in the direction of the arrow. Alternatively both apertures may be used for positioning and/or forwarding, for examples the second aperture 708 may be used to position the crimp layer accurately with respective to other components which are not part of the crimping mechanism. By locating the apertures off- centre, there may be more surface area of the crimp layer to engage with a retaining element as described in more detail below. There may be pairs of positioning apertures and pairs of forwarding apertures or other arrangements of apertures or similar indexing features.

Figures 7a to 7c illustrate different arrangements for handling multiple wires relative to the pre-formed strip 700. Figure 7a schematically shows the arrangement using a guide mechanism such as that shown in Figure 5a in which the multiple wires are handled together, e.g. by using multi-groove pulleys and sets of adjacent capillary tubes. The multiple wires form two sets of wires 740, 742 (each having three wires in this arrangement), one on each side of the crimp layer. Before insertion, both sets of wires 740, 742 are outside the crimp layer and the sets of wires are brought closer to each other to be fed into the crimps. The first set of three wires 740 is inserted together into the second crimp 750b and then the set of three wires 740 is inserted together into the first crimp 750a as the strip moves in the direction of the indicated arrow. Similarly, the second set of three wires 742 is inserted together into the second crimp 752b and then into the first crimp 752a as the strip moves in the direction of the indicated arrow. Such an arrangement may reduce tangling or crossing of the wires and may also allow the wires to be brought very close to the crimp position.

Figure 7b illustrates an arrangement in which each wire is inserted separately into the crimps 750a, 752a, 750b, 752b as the strip moves in the direction of the indicated arrow. The wires are fed from different parts of a guide mechanism. A first wire 740a in the first set of wires is inserted into the second crimp 750b of the first pair of crimps 750a, 750b at the same time as a first wire 742a in the second set of wires is inserted into the second crimp 752b of the second pair of crimps 752a, 752b. As the strip moves in the direction of the arrow, the first wire 740a is received into the first crimp 750a of the first pair of crimps 750a, 750b at the same time as the first wire 742a is inserted into the first crimp 752b of the second pair of crimps 752a, 752b.

Once the first wires 740a, 740b are in the corresponding pairs of crimps 750a, 750b, 752a, 752b, a second wire 740b in the first set of wires is inserted into the second crimp 750b of the first pair of crimps 750a, 750b at the same time as a second wire 742b in the second set of wires is inserted into the second crimp 752b of the second pair of crimps 752a, 752b. As the strip moves in the direction of the arrow, the second wires 740b, 742b are received into the respective first crimps 750a, 750b at the same time. Once each crimp 750a, 750b, 752a, 752b thus contains two wires, the strip continues to move in the direction of the arrow to receive the third wire 740c, 742c. As with the first and second wires, the third wire 740c in the first set of wires is inserted into the second crimp 750b of the first pair of crimps 750a, 750b at the same time as the third wire 742c in the second set of wires is inserted into the second crimp 752b of the second pair of crimps 752a, 752b. As the strip moves in the direction of the arrow, the third wires 740c, 742c are received into the respective first crimps 750a, 750b at the same time. Thus, as shown in the final frame in Figure 7b, three wires are within each crimp, ready for crimping. It will be appreciated that the description above explains how the wires are first inserted into the second crimp 750b, 752b of each pair of crimps and then into the first crimp 750a, 752a but the wires may be simultaneously inserted into both the first and second crimps. Figure 7c illustrates an alternative arrangement to that of Figure 7a in which each set of wires 740, 742 is initially located over (i.e. inside) the crimp layer. Each set of wires 740, 742 is moved away from each other to be inserted in the crimps. Thereafter, the order in which the wires are inserted into the crimps is the same as that shown in Figure 7a. In other words, each set of wires 740, 742 is first inserted into the respective second crimps 750b, 752b and then each set of wires 740, 742 is inserted into the first crimps 750a, 752b as the strip 700 moves in the direction of the indicated arrow.

Figure 7d schematically shows the arrangement using a guide mechanism such as that shown in Figure 5a in which the wire(s) 760 for each side are fed in from above the strip 700. As an alternative, Figure 7e shows an arrangement in which the wire(s) 760 for each side are fed in from below the strip 700. In both Figures 7d and 7e, the alignment mechanism feeds the strip 700 into the apparatus along a flat plane, e.g. horizontally. As an alternative, Figure 7f shows an arrangement in which the strip 700 is fed along a curved alignment mechanism which allows the wire(s) to be fed in a straight line. It will be appreciated that other suitable variations may be used.

Whichever way the SMA actuator wire(s) is guided into location, an alignment mechanism may be used to direct the strip through the apparatus to ensure correct alignment of the strip to the wires. Figures 8a and 8b shows a perspective and cross-sectional view of a forwarding mechanism 800 which forms part of the alignment mechanism in this arrangement. The forwarding mechanism 800 comprises a pair of support frames 810 for supporting a shaft 812 on bearings 820. Three cams 802, 804, 806 are mounted on the shaft 812. A handle wheel 814 having a handle 816 is attached to the shaft 812, e.g. via a screw mechanism. An index disk may also be attached to the shaft 812 and to a load balancer to provide the correct indexing of the shaft. Parallel keys and/or clamp rings may be used to ensure the correct alignment of the cams and handle wheel on the shaft 812. In use a user turns the handle wheel using the handle to rotate the shaft and hence simultaneously rotate the cams.

Rotation of the handle wheel causes a first cam 802 which is relatively larger than the other two cams 804, 806 to rotate and forward the strip as explained in more detail below. The first cam may thus be termed a forwarding cam. Rotation of the handle wheel also rotates the second cam 804 which moves a positioning pin as explained in more detail below. Rotation of the handle wheel also rotates the third cam 806 which moves a forwarding pin as explained in more detail below. The second and third cams 804, 806 may thus be termed positioning pin and forwarding pin cams respectively.

Each cam 802, 804, 806 has an asymmetric shape, i.e. the radius of each cam is not constant and each cam has a different range of radii compared to the other cams. These asymmetric shapes are shown in Figure 8c and it is clear that the forwarding cam 802 is larger than each of the positioning pin and forwarding pin cams 804, 806 which are both of similar size. Figure 8d is a graph plotting the change in radius and acceleration at the points marked on Figure 8c as the cams are rotated.

As shown in Figure 8d, the radius of the forwarding cam 802 is approximately constant at 33.5mm until a rotation angle of 75 degrees and the radius then increases gradually to a peak of 48mm until a rotation angle of 270 degrees before decreasing gradually to 33.5mm. For the positioning pin cam 804, the radius increases immediately on rotation from a minimum radius of 23mm to a maximum radius of 24mm and has a constant radius until approximately 240 degrees of rotation before decreasing to the minimum radius. The radius of the forwarding pin cam 806 is approximately constant at 24mm until a rotation angle of 30 degrees and the radius then increases gradually to a peak of 26mm until a rotation angle of 210 degrees before decreasing gradually back to 24mm. It will be appreciated that these radii and angles are illustrative of one particular arrangement and may be adjusted as needed to provide the required movement.

Figure 8d also plots the change in acceleration for each cam. The changes in acceleration occur in line with the changes in radius. For example, for the forwarding cam 802 as the radius begins to increase at an angle of rotation of 75 degrees, there is a step change in the acceleration from 0 to 0.5m/s ² . Approximately half way through the increase in the radius, e.g. at an angle of rotation of 130 degrees, there is another step change in the acceleration from 0.5m/s ² to -0.5m/s ² . As the radius begins to decrease at approximately 270 degrees of rotation, there is a step change from 0 to 0.9m/s ² and at 315 degrees of rotation (i.e. halfway through the decrease), there is a step change from 0.9m/s ² to -0.9m/s ² . Similar patterns of acceleration are also seen for the positioning pin and forwarding pin cams except that the step changes are equal for both increasing and decreasing cycles. The aim is to keep the acceleration of the crimp layer is as low as possible because of the tensioning of the wires. However, the returning acceleration of the forwarding pin is not important. Similarly, the movement of the pins in the vertical direction is not critical to the acceleration of the crimp layer.

Figure 8e shows the positioning and forwarding pins 844, 846 which are moved by rotation of the positioning pin and forwarding pin cams 804, 806. In this arrangement, there are two positioning pins 844 and two forwarding pins 846 which are received in corresponding positioning apertures 805 and forwarding apertures 807 on the strip. The direction of movement of a strip 700 through the groove 334 on the rail assembly 332 is indicated by the arrow. The alignment mechanism may also comprise a retainer 850 in the form of a leaf spring which applies a downward force to the strip 700 as it is moved.

Figure 8f shows that in addition to the retainer 850, the rail assembly 332 comprises a pair of projections 836 which extend partially over the groove 334 and run along the length of the rail assembly 332. Each projection 836 defines a recess 834 which runs along the length of the groove 334 at the base of the groove 334 and which receives one edge of the strip 700. By locating the edges of the strip 700 within the recesses 834, the strip 700 may be prevented from moving upwards as the positioning pins 844 are moved upwards to be located in the positioning apertures. The tip of the positioning pins 844 is shown in Figure 8f and is tapered in this arrangement. It will be appreciated that other shapes for the tip of the positioning pins (or the forwarding pins) may be used, e.g. flat, spherical or pointed.

Figure 8g is a side view of the alignment mechanism with some elements removed for clarity. Figure 8g illustrates how the rotation of the positioning pin cam 804 in a direction illustrated by the arrow B moves each positioning pin 844 up and down in the direction of arrow A. A cam follower 864 is mounted adjacent an outer edge of the positioning pin cam 804. The cam follower 864 retains contact with (i.e. follows) the positioning pin cam 804 as it rotates. A lever 854 is attached to the cam follower 864 and the lever 854 pivots about a rotation point 874 to move each positioning pin 844 from a first retracted position to a second protruding position as the positioning pin cam 804 rotates. In the retracted position, the tip of each positioning pin is just below the surface of the groove within the rail assembly and in the protruding position, the tip of the positioning pin protrudes from the surface to be located within the corresponding positioning aperture. Rotation of the lever 854 may be facilitated by ball bearings (or a similar mechanism). A return compression spring 884 biases each positioning pin 844 in the first retracted position and an extension spring which is attached an attachment location 894 biases the lever 854 in a first position which corresponds to the first retracted position. Thus, as the positioning pin cam 804 continues to rotate, the force causing the lever 854 to rotate is removed. The lever 854 pivots back to its rest position under the force from the extension spring and the return spring 884 moves each positioning pin 844 in the first retracted position.

Figure 8h is a side view of the alignment mechanism with different elements removed for clarity. Figure 8h illustrates how the rotation of the forwarding pin cam 806 in a rotational direction illustrated by the arrow B moves each forwarding pin 846 up and down in the direction of arrow A. It will be appreciated that the forwarding pin cam 806 is rotating in the same direction as the positioning pin cam 804 but the viewpoints of Figures 8g and 8h are reversed and thus the arrows B point in the opposite direction. As in Figure 8g, a combination of levers and cam followers is used to transform the rotational motion to linear motion.

In this arrangement, a cam follower 866 is mounted adjacent to an outer edge of the forwarding pin cam 806. A first lever 856 is attached to the cam follower 866 and the lever 856 pivots about a rotation point 876 to move a second lever 857 which rotates about a second rotation point 877 located at one end of the second lever 857. The opposed end of the second lever 857 to the second rotation point 877 contacts each forwarding pin 846. As the rotation continues, each forwarding pin 846 is moved from a first retracted position (shown in Figure 8h) to a second protruding position (not shown). Rotation of the levers 856, 857 may be facilitated by ball bearings 876, 877 (or a similar mechanism). A return compression spring 896 biases each forwarding pin 846 and the second lever 857 so that each forwarding pin is in the first retracted position and an extension spring 896 biases the first lever 856 in a first position which corresponds to the first retracted position. Thus, as the forwarding pin cam 806 continues to rotate, the force causing the first and second levers 856, 857 to rotate is removed. The first lever 856 pivots back to its rest position under the force from the extension spring 896 and the return spring 884 moves the second lever 857 and each forwarding pin 846 in to the first retracted position.

Figure 8i is a perspective view of the alignment mechanism with different elements removed for clarity. Figure 8i illustrates how the rotation of the forwarding cam 802 moves a sliding assembly 842 in a lateral direction shown by arrow C. The lateral direction advances a strip along through the apparatus when the forwarding pin(s) is received in the corresponding forwarding aperture(s) on a frame. The sliding assembly 842 may comprise a plurality of linear ball bearings to facilitate the lateral movement of the sliding assembly. The forwarding pins 846 are mounted on a mounting block 847 which is adjustably mounted on the sliding assembly 842 to allow adjustment of the position of the pins 846. By adjusting the position of the pins 846, the start position of the sliding assembly may be adjusted. As in Figure 8g and 8h, a combination of levers and cam followers is used to transform the rotational motion to linear motion.

In this arrangement, a cam follower 862 is mounted adjacent an outer edge of the forwarding cam 802. A lever 852 is attached to the cam follower 862 via an adjustment assembly 838. As the forwarding cam 802 rotates, initially as shown in Figure 8d, the relatively small radius part of the forwarding cam 802 is in contact with the cam follower 862 but as the rotation continues, the relatively large radius part of the forwarding cam 802 is in contact with the cam follower 862. This pushes the lever 852 and hence the sliding assembly in the direction of arrow C. As the rotation continues, the relatively small part of the forwarding cam 802 is again in contact with the cam follower 862 and an extension spring biases the lever 852 and hence the sliding assembly back to the first position. It will be appreciated that the forwarding pins are moved laterally with the sliding assembly and thus the forwarding pins can be considered to be driven by two levers - the one shown in Figure 8h and the one shown in Figure 8i.

The height of the cam follower 862 relative to the lever 825 may be adjusted by a small amount, e.g. by approximately 10mm using adjustment screws. The distance that the sliding assembly 842 moves is generally determined by the difference between the minimum and maximum radii of the cam. In the example in which the minimum radius is 33.5mm and the maximum radius is 48mm, the amount of travel will generally be 14.5mm. However, by adjusting the height of the cam follower 866, the amount of movement of the sliding assembly may be fine-tuned as illustrated in Figure 8j.

Figure 8j plots the variation in the travel way against an adjustment of the height H of the cam follower. The variation is relatively small with a height adjustment of 4.5mm resulting in a change in the travel way of just 0.1mm. However, the distance between a pair of crimps may be between 5 to 20mm and the width of each crimp may be between 300 to 800 pm. Accordingly, adjusting the position by such relatively small amounts may be critical to achieving good performance.

Figure 8j also plots the change in two angles which are shown in Figure 8k. Figure 8k is a schematic illustration of part of the circumference of the forwarding cam 802. As shown R_A corresponds to the maximum radius and R_B to the minimum radius. Delta H indicates the variation in the height of the cam follower. Two triangles A and B having a height of delta H, a hypotenuse which connects two points on the circumferences separated by the height delta H. The base of triangle A has a length x and the base of triangle B has a length y. The apex of each triangle has an angle a or b respectively which is adjusted as the height of the triangle is changed.

It will be appreciated that this is just one example of a suitable forwarding system for an alignment mechanism and other similar systems could be used. For example, indexing pins may be used to move the strip forward, pins through holes to finalise the position or any of the existing technologies for handling continuous webs of sheet metal.

Figures 9a to 9e show details of a crimping mechanism 320 which is part of the apparatus. As explained above, the crimping mechanism 320 may comprise a die tool top 324 which may be moveable in a vertical direction on die set bearings 328. As shown more clearly in Figure 9b, the crimping mechanism 320 may comprise a punch block 910 having four punches 912 which in this arrangement are set at each corner of a square. The punch block 910 also supports a pair of slack adding members 936 which are part of the slack addition mechanism described in more detail below. The punch block 910 also supports a retaining member 908 which retains the crimp layer in place during the crimping process.

Figure 9c shows a pair of anvils 914 which engage with the four punches 912 during the punching process. The pair of anvils 914 may be supported on an anvil block 916 which is on the die structure. Each anvil 914 is generally elongate with a generally planar upper surface and the anvils 914 are separated by a recess 902 which receives two terminals on the crimp layer. At one end of the anvils 914, there is a generally U-shaped trough 922 which forms part of the slack addition mechanism. Both ends of the anvils have sloped surfaces to provide a smooth surface for the wire to slide against as the wire is pushed into the recess by the projection. Figures 9d to 9e show internal detail of the crimping mechanism 302 to illustrate how the force applied with each punch may be adjusted. A spigot 942 transfers the movement of the handle into a downward force on the die tool set 324 which pushes down the punch block 910. The downward movement compresses a die spring 944 which is biased to adjust the crimping force applied by the crimping mechanism. The die tool set 324 and punch block 910 are returned to the rest position using the lever. A plurality of force sensors 946, one for each punch, measure the punch force applied by each individual punch. Monitoring the punch force allows an adjustment to be made, for example using a force adjustment mechanism 948 when the apparatus is reset.

The force adjustment mechanism 948 may comprise one or more shim washers which are mounted on top of each force sensors 946 which transfers the force from the handle down to each punch through the die spring. Each shim washer may be in the form of an annular washer. The punch force may be adjustable within any suitable range, e.g. between 100 to 250N and may be further tuned by adjusting the height of the stack of shim washers.

The distance each punch travels is controlled by a pin 954 which slides within an elongate channel. Each pin 954 protrudes from a punch sequence adjustment block 950. The height of the punch sequence adjustment block 950 may be set relative to the elongate channel using one or more shims. By using different numbers of shims for some or all of the punches, the sequence in which the punches engage the crimps may be adjusted. The adjustment may be in the range of +0.5mm to -1.5mm. The adjustment may be made on set-up or when resetting the apparatus. The adjustment may be used to compensate for different types of actuator components.

A punch alignment tool may be used to accurately align the punches with the anvils at set-up. The punch alignment tool may be configured to be placed on the anvil block 916. The punch alignment tool may comprise a pair of dowel pins which extend into the anvil block 916 and two of the punches 912 to ensure accurate alignment. It will be appreciated that the shape of the punch alignment tool will depend on the arrangement of punches which is to be used.

The apparatus is relatively complex with many sources of noise, e.g. springs, four separate punches, two separate slack adders, etc. Accordingly, it may be necessary to supplement the force sensors at the top of the crimping mechanism to more accurately measure the individual force applied by each punch. A counter force measuring tool may be placed between the anvil block 916 and the punches to accurately measure the counter force on the punches. The tool may comprise an anvil supported on a base which also supports a load cell for measuring the force. The maximum difference between the four crimping forces applied by the four punches may be less than a fixed amount, e.g. 5N but this may vary depending on the location of the four punches.

Figures 10a and 10b show variations of crimp closing using the four punch block of Figures 9a to 9e. It will be appreciated that different numbers of punches may be used and the punch sequences and arrangements may be adjusted accordingly. Figure 10a shows the sequence of crimp closing on a strip 700 which may be achieved using the punch blocks in the relatively small square arrangement of Figure 9b. The four most closely located crimps are closed in one press of the handle. Thus, the first crimps 750a, 752a in each pair of crimps on one frame are closed in the same motion as the second crimps 750b, 752b in each pair of crimps on the adjacent frame. As indicated by the numbering, the first crimps 750a, 752a may be closed slightly earlier than the second crimps 750b, 752b, e.g. by appropriate adjustment of the shims as described above. Closing pairs of crimps rather than all four crimps simultaneously may allow the wire tension on the crimps to be maintained and may minimise the flow variation within the wire around the crimp which is caused by the crimping process.

Figure 10b shows an alternative arrangement in which each of the four punches is arranged in a rectangular arrangement to allow all four crimps on one crimp layer (i.e. within a single frame) to be closed with the same press of the punch block. As shown in Figure 10a, one set of adjacent crimps may be closed slightly ahead of the other set of crimps, e.g. by adjustment of the shims as described above. In this arrangement, the second crimps 750b, 752b may be closed before the first crimps 750a, 750a again to help maintain wire tension and/or reduce flow variation.

Figures Ila to 11b show the detail of the retaining member 908 which extends from the punch block 910. Figure Ila shows the retaining member 908 in initial position when the punch block 910 is raised. As the punch block is lowered, the lower surface of the retaining member 908 engages with a crimp layer as shown in Figure 11b. Further movement of the retaining member 908 is guided by dowel pins 962 located within elongate channels and compresses return springs 964. The upper end of each elongate channel acts as an end stop to prevent further movement of the retaining member relative to the punch block 910. The retaining member 908 has a generally cross-shaped frame because there is limited space. A tapered foot may extend from the frame. The tapered foot may provide a relatively large surface area which engages centrally with the crimp layer. As shown in Figure 9b, the retaining member 908 is positioned between the punches.

Figures 12a to 12g show the detail of the slack addition mechanism which comprises a pair of slack adding members 936 and a generally U-shaped trough 922. As shown schematically in Figure 12a, as the pair of slack adding members 936 move down into the trough 922, each slack adding member 936 engages a corresponding set of wires 740 and pushes the wire(s) into the trough 922 to increase the length of wire between pairs of crimps on each side of the crimp layer. Each slack adding member 936 is separately adjustable so that a different amount of slack may be added on each side, if required, for example to alleviate differences in performance caused by different levels of tension in the spool or other inconsistencies in the wire being used. The amount of slack to be added may be determined by testing a complete crimp layer and determining an appropriate adjustment. The amount of slack may be between 0 to 250 pm.

Figure 12b is a cross-section showing the internal details to illustrate how the movement of the moveable slack adding members 936 is controlled. As described above, the moveable slack adding members 936 are mounted on a punch block 910. An individual block 970 for each slack adding member 936 is moveably mounted within the punch block 910 and initially extends beyond the lower surface of the punch block as shown in Figure 12b. Each individual block 970 has a U-shaped cross-section to minimise the size of the block within the crimping mechanism. The movement of each block 970 is controlled in a linear direction by a pair of dowel pins 972 which extend through the block 970. As the blocks 970 move within the punch block 910, a return spring 976 for each dowel pin 972 is compressed. The compression of each return spring 976 provides the force to return the moveable slack adding member 936 to its original rest position. Above each dowel pin 972 is an upper end stop 974 which prevents further upward movement of the dowel pin 974. A corresponding lower end stop (not shown) limits further downward movement of the dowel pin. Figures 12c and 12d are cross-sectional views showing how the distance that the wire is forced into the groove 922 and hence the amount of slack added to each set of wire(s) between the pairs of crimps is controlled by a respective pin 980 one end of which forms an adjustable end stop 982. As shown in Figure 12c, the upper end of each respective pin 980 is flush with an upper surface of the rail assembly 332 and thus does not engage with a surface of the block 970 until the punch block is fully down. Each slack adding member 936 is thus able to travel the maximum distance into the groove. Accordingly, in this arrangement, the maximum amount of slack may be added. For example, each slack adding member 936 may be able to travel 1.2mm which may provide 375pm of slack for an actuator assembly as shown in Figure la.

In Figure 12d, the upper end of each respective pin 980 protrudes from an upper surface of the rail assembly 332 and engages with a lower surface of the block 970 from which each slack adding member 936 protrudes. The pins 980 thus prevent further downward motion of the blocks 970 but the punches are free to continue moving downwards to close the crimps. In this arrangement, a minimum amount of slack may be added.

As shown in Figures 12c and 12d, the amount that the pins 980 protrude is controlled by mounted the lower end on a lever 982. A micrometre 984 connects to the lever 982 to change the angle of the lever 982 and hence the amount of protrusion for each pin 980. As shown in Figure 12c, each lever 982 is set at an angle to the axis of the pin 980 and in Figure 12d, each lever 982 is generally parallel with each pin 980. Each pin 980 is individually controllable and may protrude by different amounts so that different amounts of slack may be added to each set of wire(s). Springs 986 are provided to bias the pins 980 in the position set by the micrometre so that the downward movement of the blocks 970 does not force the pins 980 downwards.

Figures 12e and 12f show two alternative arrangements for positioning the moveable slack adding members 936 relative to the punches for closing crimps on a strip 700. Figure 12e corresponds to the arrangement shown in Figures 9b and 10a in which the punches are arranged at the corners of a relatively small square to close the first crimps 750a, 752a in each pair of crimps on a first frame and the second crimps 750b, 752b in each pair of crimps on an adjacent, subsequent frame. In this arrangement, the second crimps 750b, 752b of the first frame have been closed by a previous movement of the crimping mechanism and thus the slack adding members 936 are positioned to add slack to the wires extending from the second crimps 750b, 752b before the first crimps 750a, 752a of the first frame are closed. In other words, the slack adding members 936 are positioning ahead of the punches.

Figure 12f corresponds to the arrangement shown in Figure 10b in which the punches 912 are arranged at the corners of a rectangular to close all the crimps 750a, 752a, 750b, 752b in a single frame. In this arrangement, the slack adding members 936 are positioned to add slack to the wires extending from the second crimps 750b, 752b before the first crimps 750a, 752a of the first frame are closed. In other words, the slack adding members 936 are positioning between the punches.

Before the crimps are closed, it is necessary that the tensioned wires are placed within the crimp and Figures 13a and 13b illustrate two arrangements of crimps to which the apparatus may be adapted. In Figure 13a, the crimp layer 1326 is generally planar and comprises a pair of crimps 1350, 1352 each of which has a first part which extends from the generally planar crimp layer 1326 and a second part which is set at an angle to the first part. Downward movement in the direction of the arrows A pushes the second part toward the first part to close the crimp. This is a commonly used type of crimp arrangement and it is necessary to move the wires downwards and sideways into the crimps as explained in more detail below.

In the arrangement shown in Figure 13b, the first part of the crimps 1360, 1362 is set at an angle to the generally planar crimp layer 1336 and the second part of the crimps 1360, 1362 is generally at right angles to the planar crimp layer 1336. Thus, in the arrangement of Figure 13b, the wires simply need to be moved downwards into the crimps. The movement of the wires is simplified and such crimps may be used particularly with the arrangement shown in Figure 7f having a curved strip. However, it is necessary to adapt the profile of the punches to provide an angled force as shown by the arrows, e.g. by using punches having inclined contact surfaces.

Figure 14 shows a flow chart of example steps for assembling an actuating module comprising at least one SMA actuator wire. As shown, there may be a first set-up phase in which the steps may be carried out in parallel as indicated or sequentially. The process may comprise placing the actuating module on the rail assembly and as described above the actuating module may be in a pre-formed strip (S1400). The strip may comprise a plurality of punches and the first part of the set-up may be to align the initial crimps to be closed with the punches (S1402).

As explained above, the positioning pin may be used to accurately locate the strip and thus as shown in Figure 15a, the positioning pins 844 may be raised to protrude from the surface of the rail assembly. The corresponding positioning apertures on the frame can be located on the raised positioning pins 844. The lateral motion of the positioning pins 844 is caused by rotation of the positioning pin cam to raise the lever 854 which pushes the positioning pins 844 upwards. The forwarding pins 846 together with their associated lever 857 is in its original rest position. Thus, the forwarding pins 846 do not protrude above the rail assembly.

Returning to Figure 14, the other part of the set-up phase is for the user (or automated system) to unspool and tension the sets of wire(s) for each side of the actuating module (S1404). The tensioned wire(s) are then guided towards the rail assembly using the guide mechanism (S1406) which as explained above may comprise one or more multi-groove pulleys and capillary tubes. The guide mechanism brings the wires close to the crimps and so the crimping mechanism may be activated, e.g. by lower the handle to move the die set top closer to the die base.

In an arrangement such as that shown in Figure 13a, the pulleys and capillary tubes may have moved the wires to a position adjacent the crimps but the wires need to be move sideways into the crimps. Accordingly, the first step of the crimping phase may comprise guiding the wires into the crimps (S1408). As shown in Figure 15b, this part of the guide mechanism may be incorporated onto the punch block 910 and may be termed an insertion mechanism. The guide mechanism may thus further comprise a pair of levers 1510 which engage with cam followers 1514 on the pulley supports 1512 as the punch block is lowered. The pulley supports 1512 are raised above the surface of the rail assembly 332 and thus are engaged by the levers 1510 before the punches and/or slack adding members are activated. The capillary tubes are attached to the pulley supports and thus move with the pulley supports.

Figure 15c shows the levers 1510 in contact with the cam followers 1514. The levers 1510 may be mounted to the die set top via bearings 1516 and may pivot about the location of the bearings. The attack point of each of the levers 1510 may be adjusted by a separate adjustment mechanism 1518 which may be a screw. A pair of springs 1520, one for each lever 1510, may be used to bias the lever in the position shown in Figure 15c, i.e. in a generally vertical orientation.

Figure 15d shows the detail of how each pulley 516c, 518c and its respective pulley support 1512 are moveably mounted to the rail assembly 332. Each pulley support 1512 is supported on a lever 1522 (also termed a member or a slider) which is moveable on linear bearings (not shown) along an angle of about 20 degrees. Movement of the levers 1522 is adjustable using adjustable end stops 1526. Once the movement of the levers 1522 reaches these end stops 1526, the levers 1510 mounted to the die top set deflect about the bearing point 1516. When the die top set and punches are returned to their original position after the crimping, the levers 1522 are returned to their original position by return springs 1528.

Figure 15e shows one set of wires 742 after it has been guided into a crimp 752a (for illustration purposes only - the first crimp in the second pair of crimps). The direction of motion of the capillary tubes between the position in which the set of wires are adjacent the crimp and the position in which the set of wires is within the crimp (as shown) is illustrated by the arrow.

It will be appreciated that the use of the insertion mechanism comprising levers and cam followers which move the capillary tubes may be replaced by any suitable mechanism for moving the wires into the crimps. For example, the wire(s) may be manipulated by a lever which takes the wires from one side of the crimp, moves around the crimp and places the wire(s) inside the crimp. The lever can be moved by any suitable manual or mechanical device. The path of the wires around and into the crimp may have any suitable shape, e.g. round, rectangular or elliptical. Alternatively, the wires may be pushed or pulled into the crimps using sliders, such as mechanical fingers or hooks. The movement of the slider may be a single movement or a combined movement which may be manually or automatically controlled.

Other arrangements of sliders may also be used. For example co-operating rotating and linear sliders may be used. The linear slider may have a sloping surface having an upper point adjacent the crimp. The rotating slider may have an eccentric shape with a protruding part. Initially the wires are below and to one side of the crimp. As the rotating slider rotates, the protruding part engages with the wires and slides them along the linear slider towards the crimp. Once the wires reach the top of the linear slider, they are dropped into the crimps and held in place by wire tension. As an alternative to the use of separate rotating and linear sliders, the movement may be created by a single slider incorporating the two features, namely an inclined plane and an eccentric shaft. While the single slider is turning, it moves the wires down and sideward. With this combined movement, the wires may be placed in the crimps. The shape of the single slider is such that it does not interfere with the forwarding of the strip.

Returning to Figure 14, once the wire(s) are within the crimp(s), the next optional step is to add slack (S1410), for example using the slack addition mechanism described above. The crimps are then closed (step S1412), using the punches and anvils. The crimps may be closed simultaneously or near simultaneously in sequence, for example as described above. In the arrangement above, four crimps are closed in a single crimping phase but it will be appreciated that other numbers may be closed. Once the crimping is complete, the crimping mechanism is released (S1416), e.g. the various return springs return the die tool set and punch block to the starting position when the handle is released by the user.

The next phase is the moving phase to align the next portion of the strip with the punches so that the next set of crimps may be closed (S1416). As shown in Figure 15f, the positioning pins 844 remains raised and the forwarding pins 846 are also raised by activating the lever 857 using the forwarding pin cam as described above. By keeping the positioning pins 844, the alignment of the crimp layer is maintained while the forwarding pins 846 are located in the corresponding locating apertures. As shown in Figure 15g, once the forwarding pins 846 are engaged, the positioning pins 844 may be retracted to allow the strip to be advanced by movement of the forwarding cam. Once the next portion of the strip is in place, the crimping phase may be repeated by guiding the next portion of the wire(s) into the crimp(s) and so on.

Figure 15h shows the timing cycle of each of the pins and movement of the sliding assembly (and hence strip) between two crimping steps. When the first crimping step occurs (at the left point on the graph), the positioning pin is raised, the forwarding pin is lowered and there is no movement (transport) of the sliding assembly. After crimping, the forwarding pin is raised and the positioning pin is maintained in a protruded position until the forwarding pin is fully raised. As indicated by the first dotted line connecting timing events, the forwarding pin is then lowered. As indicated by the second dotted line, there is a small time lag between the time at which the forwarding pin is fully lowered and the movement of the sliding assembly begins. As shown, the sliding assembly moves steadily forwards before remaining stationary. It is important that the acceleration of the sliding assembly (and hence the strip) is as low as possible to minimise stress on the wire(s) held in the crimps.

Once the sliding assembly has travelled to the correct position indicated by the next dotted line, there is another small time lag before the positioning pin is moved upwards again. Once the positioning pin is raised, the forwarding pin is lowered. Again as indicated by the next dotted line one pin is lowered immediately when the other is fully raised. Once the forwarding pin is lowered, there is a small time lag as indicated by the final dotted line and the sliding assembly is then returned to its original position. The return phase of the sliding assembly may be quicker than the first movement of the sliding assembly because the strip is not attached to the sliding assembly. Once the sliding assembly is back in its original position, the next crimping step can occur (right hand line on the graph). The index disk may comprise a groove which provides a cue to the user that the wires and strip are in the correct place for the next crimping step.

The relative timing of the pins and movement of the strip needs to be carefully controlled and in the arrangement described above is achieved by appropriate shaping and sizing of the three cams. However, any suitable mechanism may be used.

Figures 16a to 16c illustrate an alternative guide mechanism for guiding sets of wires towards and into the crimps. As in the arrangement above, there is a rail assembly for aligning a strip comprising a plurality of crimps with the wires and the punches. The guide mechanism comprises a first slider 1610 for each set of wires 1620, 1622 and a second slider 1616 which is spaced apart from the pair of first sliders 1610. The first sliders 1612 are placed along the rail assembly at a location which is spaced from the crimping position to improve accessibility. The second slider 1616 is placed along the rail assembly at a location which is adjacent to the crimping position. As shown more clearly in Figure 16c, the two sets of wires 1620, 1622 are fed towards the crimps from a source point which is on the opposite side of the strip to the crimp into which they are being fed. Thus, the two sets of wires 1620, 1622 cross during the guiding and inserting process. The guide mechanism may be considered to be a weaving mechanism because of the crossing movement of the wires.

The first slider comprises a holder 1612 for maintaining the wires in each set separate from one another. Both of the first sliders 160 move along an axis which is generally perpendicular to the axis of the rail assembly 1622 but in the same plane. Thus, in this arrangement the first sliders move in a generally horizontal movement as indicated by the arrows. A return spring 1614 is attached to each first slider 1612 to bias the first slider in a first, rest position in which the first sliders are relatively close to one another. Depending on the arrangement of the crimps on the strip, the first sliders 1612 may be placed at different heights for each set of wires and may be separately adjusted to be moveable by different amount.

The second slider 1616 is mounted across the groove in the rail assembly in which the strip is located in use. As indicated by the arrow, the second slider 1616 moves in a direction which is generally perpendicular to the direction of movement of the first sliders 1612 (e.g. in the arrangement, vertically).

Figure 16b schematically illustrates the movement of both the first and second sliders which may also be termed moving elements which move on dowel pins. Initially, as the set of wires 1620 is fed towards the crimp 1618, the first sliders are in a first position in which they are relatively close to one another. In this position the wires are crossing and creating the minimal spacing for feeding both sets of wires towards but not into the respective crimps. Each set of wires is supported by the second slider 1616 which is in a first raised position relative to the crimp layer 1624 and the position of the wires is shown schematically by the top line in Figure 16b

As indicated by the arrow 1, the next step is for the second slider 1616 to move to its second position in which the second slider 1616 and the set of wires 1620 are closer to the crimp layer 1624. In other words, the second slider 1616 pushes the sets of wires down. The new position of the set of wires is indicated by the middle line. As indicated by arrow 2, once the wires have been lowered, the first sliders are moved away from one another, e.g. outwards, which moves the wires into the crimp 1618 as indicated by the lowest line. The tension of the wires may prevent the wires slipping back out of the crimp once they have been hooked into the crimps. The crimps may then be closed using the crimping mechanism described above, or any suitable variant. As described above, there are three user operated mechanisms; a handle 426 for feeding one or more wires tensioned wires into the apparatus, a handle 816 for accurately locating each crimp relative to the corresponding punch and a handle 312 for moving the punches to close the crimps. It will be understood that some or all of these processes may be performed automatically, e.g. by a robotic arm or other mechanised and automated process. It will be understood that parts of the die tool set may be moveable in a way to permit access to a human user or robotic arm. Accordingly, the present techniques also provide methods for assembling an actuating module comprising at least one SMA actuator wire.

In a related approach of the present techniques, there is provided a non- transitory data carrier carrying processor control code to implement any of the processes or methods described herein. In other words, the processor control code when controlling the modules may cause the modules to implement any of the processes or methods described herein.

As will be appreciated by one skilled in the art, the present techniques may be embodied as a system, method or computer program product. Accordingly, present techniques may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects.

Furthermore, the present techniques may take the form of a computer program product embodied in a computer readable medium having computer readable program code embodied thereon. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

Computer program code for carrying out operations of the present techniques may be written in any combination of one or more programming languages, including object oriented programming languages and conventional procedural programming languages. Code components may be embodied as procedures, methods or the like, and may comprise sub-components which may take the form of instructions or sequences of instructions at any of the levels of abstraction, from the direct machine instructions of a native instruction set to high-level compiled or interpreted language constructs. Embodiments of the present techniques also provide a non-transitory data carrier carrying code which, when implemented on a processor, causes the processor to carry out any of the methods described herein.

The techniques further provide processor control code to implement the above-described methods, for example on a general purpose computer system or on a digital signal processor (DSP). The techniques also provide a carrier carrying processor control code to, when running, implement any of the above methods, in particular on a non-transitory data carrier. The code may be provided on a carrier such as a disk, a microprocessor, CD- or DVD-ROM, programmed memory such as non-volatile memory (e.g. Flash) or read-only memory (firmware), or on a data carrier such as an optical or electrical signal carrier. Code (and/or data) to implement embodiments of the techniques described herein may comprise source, object or executable code in a conventional programming language (interpreted or compiled) such as C, or assembly code, code for setting up or controlling an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or code for a hardware description language such as Verilog (RTM) or VHDL (Very high speed integrated circuit Hardware Description Language). As the skilled person will appreciate, such code and/or data may be distributed between a plurality of coupled components in communication with one another. The techniques may comprise a controller which includes a microprocessor, working memory and program memory coupled to one or more of the components of the system.

It will also be clear to one of skill in the art that all or part of a logical method according to embodiments of the present techniques may suitably be embodied in a logic apparatus comprising logic elements to perform the steps of the above-described methods, and that such logic elements may comprise components such as logic gates in, for example a programmable logic array or application-specific integrated circuit. Such a logic arrangement may further be embodied in enabling elements for temporarily or permanently establishing logic structures in such an array or circuit using, for example, a virtual hardware descriptor language, which may be stored and transmitted using fixed or transmittable carrier media.

In an embodiment, the present techniques may be realised in the form of a data carrier having functional data thereon, said functional data comprising functional computer data structures to, when loaded into a computer system or network and operated upon thereby, enable said computer system to perform all the steps of the above-described method.

Those skilled in the art will appreciate that while the foregoing has described what is considered to be the best mode and where appropriate other modes of performing present techniques, the present techniques should not be limited to the specific configurations and methods disclosed in this description of the preferred embodiment. Those skilled in the art will recognise that present techniques have a broad range of applications, and that the embodiments may take a wide range of modifications without departing from any inventive concept as defined in the appended claims.