Field

The present invention relates to a wearable article that provides haptic feedback to a user, in particular to a haptic glove. The present invention in particular relates to such haptic gloves using shape memory alloy (SMA) wires for providing haptic feedback.

Background

Haptic gloves may be used to provide haptic or tactile feedback to a user's hand, for example when used in combination with virtual reality (VR) or augmented reality (AR) technology. Haptic gloves may provide a variety of sensations to a user's hand, ranging from giving the impression of gripping a virtual object (e.g. in a video game) to imitating texture and other surface structure on such a virtual object. Existing haptic gloves, however, are still limited in their capability of providing accurate haptic feedback and tracking a user's hand movement. Additionally, the mechanisms driving existing haptic gloves are large and heavy, limiting the adoption of haptic gloves in VR applications.

Summary

The present invention is concerned with providing an improved haptic glove that overcomes the drawbacks of existing haptic gloves. In particular, the present invention is concerned with providing a compact haptic glove. The present invention is also concerned with providing a haptic glove with improved tracking of finger movement, and improved tactile feedback both for sensations such as gripping an object as well as feeling the texture or surface structure of an object.

According to the present invention, there is provided a haptic glove for providing haptic feedback to a user's hand, the haptic glove comprising: a base portion and one or more finger portions extending from the base portion, wherein each finger portion is pivotally movable relative to the base portion, and wherein each finger portion comprises a plurality of finger segments pivotally movable relative to each other; one or more cables, each comprising a distal end connected to a respective finger portion and a proximal portion extending towards the base portion; and one or more cable control assemblies for selectively constraining movement of the proximal portion of a respective cable relative to the base portion, wherein the base portion and the finger segments comprise rigid parts that are, in use upon constraining movement of the proximal end of a respective cable, directly engaging with each other.

The rigid parts of the base portion and the finger segments are directly engaging each other in use upon constraining movement of the proximal end of a respective cable. So, the rigid parts of the base portion and the finger segments may be in direct contact with each other. A compressive force may thus be carried by the finger segments and base portion. In combination with the cable, the cable finger segments are thus configured to form a force-locked loop upon constraining movement of the proximal portion of the cable, with the cable in tension and the finger portion in compression, thereby constraining bending of a respective finger portion relative to the base portion.

The compressive force resulting from tension in the cable may be carried entirely by the finger segments. So, as opposed to haptic gloves that do not provide for such rigid parts that directly engage each other, but comprise flexible finger portions, no compressive force is acting on a user's finger. The user thus receives more natural and accurate haptic feedback that more closely resembles holding an object than wearing a glove. The structure of the haptic glove according to the present invention thus may provide improved haptic feedback compared to conventional haptic gloves.

According to the present invention, there is thus also provided a haptic glove for providing haptic feedback to a user's hand, the haptic glove comprising: a base portion and one or more finger portions extending from the base portion, wherein each finger portion is pivotally movable relative to the base portion, and wherein each finger portion comprises a plurality of finger segments pivotally movable relative to each other; one or more cables, each comprising a distal end connected to a respective finger portion and a proximal portion extending towards the base portion; and one or more cable control assemblies for selectively constraining movement of the proximal portion of a respective cable relative to the base portion, wherein the combination of cable, base portion and finger segments, is configured in use upon constraining movement of the proximal portion of the cable to form a force-locked loop, with the cable in tension and the finger portion in compression, thereby constraining bending of a respective finger portion relative to the base portion.

In some embodiments, the one or more finger portions are arranged, in use, generally to extend along the dorsal side of a user's finger. The finger portions may extend from the dorsal side of a user's finger by less than 2cm, preferably 1cm, for example. The finger portions may be arranged to contact and conform to the user's finger along the entire length of the finger portion. As such, a compact haptic glove may be provided that is easier to wear than comparably clunky existing haptic gloves.

In some embodiments, the number of finger segments in each finger portion is greater than 3, preferably greater than 5, further preferably greater than 10. In some embodiments, the number of finger segments in each finger portion may be greater than 20. A larger number of finger segments may allow the finger portion to conform to the various lengths of finger, and so may be used by a wider variety of user's. This is because the finger portion may bend at any point between two finger segments. In some embodiments, at least some of the finger segments are removable arranged in the finger portion so as to allow modification of the finger portion to adapt to different finger lengths.

In some embodiments, the finger segments have an extent in a direction along the finger portion of less than 2cm, preferably less than 1cm, further preferably less than 0.8 cm. Shorter finger segments allow the finger portion to conform to the various lengths of finger, and so may be used by a wider variety of user's.

In some embodiments, the finger portion comprises an alternating arrangement of i) one or more relatively smaller finger segments and ii) one or more relatively larger finger segments. The extent of the relatively smaller finger segments in a direction along the finger portion is less than 2cm, preferably less than 1.5cm, further preferably less than 1 cm. The extent of the relatively larger finger segments in a direction along the finger portion is more than 1cm, preferably more than 1.5 cm, further preferably more than 2 cm. The relatively smaller finger segments may, in use, be arranged adjacent to the joints of a user's finger and the relatively larger finger segments may, in use, be arranged between the joints of a user's finger. This reduces the number of finger segments required, while still allowing the finger portion to conform to a range of user's fingers.

In some embodiments, the finger segments between the proximal finger segment adjacent to the base portion and the distal finger segment furthest away from the base portion have an equal extent in a direction along the finger portion. In general, the majority of finger segments, preferably at least 75% or at least 90% of finger segments, may be identical. This may make manufacture of the finger portion simpler. In some embodiments, the finger segments comprise a curved surface, such as a concave surface, configured to conform to the back of a user's finger. This allows the finger segments to sit closer to the user's finger, making the finger portion more compact.

In some embodiments, at least the finger segment that is most distal from the base portion comprises a palmar portion that, in use, is arranged on the palmar side of a user's finger and is arranged to transfer a force from the user's finger to the cable and the corresponding finger portion. The palmar portion may be coupled to the dorsal portion of the finger segment by any suitable means, for example by straps. The palmar portion may comprise a rigid part, thus allowing the haptic glove to be made more sturdy and allowing further features to eb incorporated into the palmar portion. For example, in some embodiments, the palmar portion of at least the finger segment that is most distal from the base portion comprises a haptic actuator configured to provide, on selective actuation, localized haptic feedback to a user's fingertip.

In some embodiments, one or two of the finger segments arranged in use between the joints of a user's finger comprises a palmar portion that, in use, is arranged one the palmar side of a user's finger and transfers a force from the user's finger to the cable and the corresponding finger portion. In general, the palmar portion may be provided to two or more finger segments, for example to three finger segments.

In some embodiments, each finger segment comprises a pair of protrusions arranged to protrude towards, and at least in use be in direct contact with, an adjacent finger segment. Each protrusion may comprise a pivoting point about which the respective finger segment is pivotable relative to the adjacent finger segments. Each finger segment may further comprise a pair of depressions arranged to receive the pair of protrusions of an adjacent finger segment.

In some embodiments, the coupling between adjacent finger portions may allow pivotal movement. The coupling may comprise two coupling portions provided on opposite sides of the finger segment, optionally symmetrically arranged relative to the cable. The coupling portions between adjacent finger segments may be provided in a plane lying closer to the joints of a user's finger than a surface configured to engage the dorsal side of a user's finger.

In some embodiments, each finger portion comprises a coupling element extending along the length of the finger portion, the coupling element configured to couple the finger segments to one another. In some embodiments, the coupling element comprises a pair of coupling cables provided, in use, on opposite sides of a user's finger. Providing the coupling element on the sides of a user's finger brings the pivoting point about which the segments pivot relative to each other closer to the actual plane of rotation in a user's finger joint. As such, a more natural feel of the haptic glove is achieved.

In some embodiments, the coupling cables are arranged to connect at a point adjacent to the base portion. This may allow the finger portion to move laterally relative to the base portion.

In some embodiments, viewed in a direction along the finger portion, the cable and the pair of coupling cables form the corners of an isosceles triangle. Such a symmetric arrangement reduces the risk of inadvertent lateral forces applied by the cable to the finger portion, thus improving haptic feedback.

In some embodiments, each finger portion comprises exactly three or exactly two finger segments. So, one finger segment per phalanx of a user's finger may be provided. The base portion and/or finger portions comprise a shell configured, in use, at least partially to surround a user's hand. Each finger portion and each finger segment is configured, in use, to surround a finger of a user's hand. Such an embodiment may provide a more stable and robust haptic glove.

In some embodiments, the finger segment adjacent to the base portion is pivotally movable about two orthogonal axes that are perpendicular to a direction along the finger portion. So, the finger segment allows for both lateral and vertical movement of a finger, thus reducing the constrains on natural finger motion of a user and improving the feel of a user wearing the haptic glove. The base portion and/or the finger segment adjacent to the base portion comprises a curved surface guiding pivotal movement of the finger segment relative to the base portion about an axis perpendicular to the palm of a user's hand.

In some embodiments, the base portion and/or each finger segment is integrally formed, preferably by injection molding. This makes manufacture of the structure of the haptic glove simpler. The base portion and/or each finger segment may be formed from a polymer, for example.

In some embodiments, the base portion and/or the one or more finger portions comprise integral guide channels for guiding the one or more cables from the finger portion towards the base portion. This improves the reliability of cable control, ensuring that the cables remain in place where they are required.

In some embodiments, the haptic glove comprises multiple cables per finger portion, one cable connected to a finger segment that is arranged distally to the base portion and at least one other cable connected to a finger segment arranged, in use, between the joints of a user's finger. This may allow for more complex haptic feedback to be delivered to a user.

In some embodiments, the multiple cables per finger portion are controlled by a common cable control assembly. The multiple cables per finger portion may be wound on a multi-diameter reel, each cable wound around a different diameter portion of the multi-diameter reel. This is one arrangement of gearing movement of the cables and corresponding finger segments relative to each other. The gearing may be so as to imitate the natural curling of a user's finger. As such, an improved haptic sensation can be delivered without complicating cable control.

In some embodiments, the cable control assembly comprises a retraction mechanism configured to apply a retraction force to the cable. This ensures that the cable may remain retracted when the user does not curl a finger.

Brief description of the drawings

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

Fig. 1 is a schematic overview of aspects of a haptic glove;

Fig. 2A and 2B are schematic perspective and side views of the structure of the haptic glove according to embodiments of the present invention;

Figs. 3A-F are schematic views of the structure of the haptic glove according to embodiments of the present invention;

Figs. 3A-F are schematic views of the structure of the haptic glove according to embodiments of the present invention; Figs. 4A-F are schematic views of the structure of the haptic glove according to embodiments of the present invention;

Figs. IE to 1H schematically show some of the details of the alternative main body of Figs. 1C and ID;

Figs. 5A and 5B show a multi-diameter reel implementing multi-cable control in the haptic glove;

Fig. 6 shows a schematic example of a constrain mechanism forming part of a cable control assembly;

Figs. 7A-C show further examples of a haptic glove structure;

Figures 8A and B show an example of a haptic actuator for localized haptic feedback;

Figures 9A-C show arrays of haptic actuators for localized haptic feedback; and

Figure 10 shows a haptic glove including a joystick.

Detailed description

Overview of the haptic glove

Fig. 1 schematically depicts a haptic glove 1 in accordance with the present invention. The haptic glove 1 is configured to be worn on a user's hand. The haptic glove 1 comprises a base portion 10 and one or more finger portions 20. The finger portions 20 are pivotally movable relative to the base portion 10. Each finger portion 20 may comprise a plurality of finger segments 22 that are pivotally movable relative to each other and relative to the base portion 10. The base portion 10 and the one or more finger portions 20 make up the structure or exoskeleton of the haptic glove 1. The base portion 10 is herein used as a reference frame relative to which movement of other components of the haptic glove 1 is described (unless otherwise indicated), but it will be appreciated that the base portion 10 in general may be movable itself and may comprise or be made up of parts that are movable relative to each other. Details and embodiments of the base portion 10 and the one or more finger portions 20 are described below.

The haptic glove 1 further comprises one or more cables 30 that is or are coupled at one end (herein referred to as the "distal end") to a respective finger portion 20. Multiple cables 30 may be provided per finger portion 20, as described in more detail below. The cable 30 may be any elongate element capable of carrying a tensile force. The cable 30 may be deformed by forces acting laterally to the tensile force carried by the cable 30.

The cable 30, in particular movement of the cable 30, is controlled by a cable control assembly 100. The cable control assembly 100 may control the cable 30 passively, i.e. the cable control assembly 100 may selectively constrain (i.e. resist by a frictional force or bias force, or even prevent) movement of the cable 30. The cable control assembly 100 need not actively move the cable 30. In some embodiments, however, the cable control assembly 100 may actively pull on the cable 30 so as to move the finger portion 20 relative to the base portion 10.

The cable control assembly 100 may be provided on the base portion 10, as schematically shown. However, in general, the cable control assembly 100 may also be provided on the finger portions 20, or be distributed between the base portion 10 and the finger portions 20. The end of the cable 30 that is not coupled to the finger portion 20 (herein referred to as the "proximal end" or "proximal portion") may be coupled to the cable control assembly 100. The cable control assembly 100 may provide haptic feedback to a user by constraining, i.e. resisting or even preventing, movement of the cable 30. Details and embodiments of the cable control assembly 100 are described below.

The cable control assembly 100 may comprise at least one constrain mechanism 120, for example in the form of a locking mechanism 120a, a braking mechanism 120b and/or a spring mechanism 120c. The cable control assembly 100 may selectively engage the constrain mechanism 120. So, the constrain mechanism 120 may selectively constrain movement of the cable 30 relative to the base portion 10. This selectively locks, brakes or otherwise resists (e.g. applies a force that opposes) movement of the finger portion 20 relative to the base portion 10, thereby providing haptic feedback to the user.

Optionally, the cable control assembly 100 comprises at least one retraction mechanism 110. The retraction mechanism 110 may retract the cable 30, for example upon un-bending of the finger portions 20. The retraction mechanism 110 may provide a continuous or permanent biasing force for retracting the cable 30. The retraction mechanism 110 may be embodied by a resilient element, such as a spring (e.g. compression or tension spring, or a torsion spring) that provides the biasing force. In some embodiments, a dedicated retraction mechanism 110 is not provided.

Optionally, the cable control assembly 100 may comprise a multi-cable coupling 170, thereby enabling multi-cable control. So, some provision may be made for the cable control assembly 100 to control multiple cables 30 simultaneously. Each or at least one of the retraction mechanism 110 and/or the constrain mechanism 120 may thus act on multiple cables 30 simultaneously, such that a single retraction mechanism 110 and/or constrain mechanism 120 may act on multiple cables 30. This may make the cable control assembly 100 more compact and simpler. Alternatively, the cable control assembly 100 may control each cable 30 independently. Each retraction mechanism 110 and/or the constrain mechanism 120 may thus act on a single cable 30 only, such that a dedicated retraction mechanism 110 and/or constrain mechanism 120 is provided for each cable 30. This may provide more accurate cable control, and thus improved haptic feedback.

Optionally, the cable control assembly 100 comprises a position sensing arrangement 190. The position sensing arrangement 190 may determine a position of a finger portion 20 relative to the base portion 10. The position sensing arrangement 190 may, for example, determine the position of the cable 30 relative to the base portion 20. A processor (not shown) or other control circuit may receive the position data and make a determination as to whether or not to provide haptic feedback at least in part based on the position data.

Optionally, the haptic glove 1 comprises one or more haptic actuators 200 for providing localized haptic feedback to a user. The one or more haptic actuators 200 may be provided on the finger portion 20 (for example near the fingertip of a user), to selectively provide a localized haptic sensation to a specific portion of the user's hand (for example to the fingertip of the user). The one or more haptic actuators 200 may be SMA haptic actuators, i.e. comprise an SMA wire configured, on contraction, to provide localized haptic feedback. An SMA haptic actuator is compact and flat and so particularly suitable for incorporation in the haptic glove 1.

Details of the haptic glove 1 are described below. It will be appreciated that any of the embodiments of the structure of the base portion 10 and/or finger portion 20 may be combined with any of the embodiments of the cable control assembly 100 described below. Furthermore, even though the parts of the cable control assembly 100 are described below in relation to the haptic glove 1, it will be appreciated that these parts may find application in devices other than the haptic glove and may form embodiments of the present invention in their own right.

Structure of the haptic glove 1

Figs 2 to 4 show embodiments and aspects of the structure of the haptic glove 1, comprising the base portion 10 and the one or more finger portions 20. In some embodiments, the combination of base portion 10 and one or more finger portions 20 may also be referred to as a main body, exoskeleton or linkage mechanism of the haptic glove 1.

The base portion 10 is arranged, in use, to at least partially be arranged adjacent to a user's hand 2. Although not shown, the base portion 10 may extend over the wrist of a user's hand, thus providing additional space for other components of the haptic glove 1. In its simplest form, the base portion 10 may comprise a plate provided on the rear of a user's hand. The base portion 10 may be fixed relative to a user's hand, for example using suitable straps. The base portion 10 may also be worn on the user's hand, so as to partially or entirely surround a user's palm.

One or more (e.g. four or five) finger portions 20 may depend from the base portion 10. The finger portion 20 comprises a proximal end arranged next to the base portion 10 and a distal end arranged away from the base portion 10. Each finger portion 20 is to be arranged on or adjacent to a user's finger (where the thumb is considered to be one of the fingers). Each finger portion 20 may be pivotally arranged relative to the base portion 10, i.e. the distal end of each finger portion 20 may pivot relative to the base portion 10. The finger portion 20 may pivot or bend relative to the base portion 10 at least in a direction substantially orthogonal to a user's palm, so as to allow bending of the user's finger. The finger portion 20 may additionally be laterally movable relative to the base portion 10, i.e. in a plane substantially parallel to a user's palm, so as to allow for lateral movement of a user's finger. This avoids constraining natural movement of a user's finger, making the haptic glove 1 more comfortable to wear and providing a more natural feel to a user.

The haptic glove 1 may comprise five finger portions 20, one for each finger and the thumb of a user's hand. In some embodiments, the haptic glove 1 may comprise fewer than five finger portions 20, for example four finger portions 20 (for surrounding a user's fingers other than the thumb) or fewer finger portions 20. In some embodiments, a finger portion 20 may be provided to be worn on multiple fingers. For example, a single finger portion 20 may be worn on the pinkie finger and ring finger of a user's hand together, such that the pinkie finger and ring finger move together.

In preferred embodiments, each finger portion 20 comprises one or more finger segments 22, e.g. a plurality of segments 22 mechanically connected in series so as to form a chain of linkages. The segments 22 may be pivotally movable with respect to each other and with respect to the base portion 10, so as to allow bending and/or curling of a user's finger while remaining adjacent to the user's finger. One or more bearings 23 may be provided between adjacent finger segments 22 and between the base portion 10 and the finger portion 20, so as to allow relative movement of the finger segments 22 relative to each other and relative to the base portion 10. The finger segments 22 may comprise rigid parts, i.e. be rigid, and in use be in direct contact with one another. This may provide improved haptic feedback compared to haptic gloves in which such a structure is not provided.

The haptic glove 1 comprises one or more cables 30. The haptic glove 1 may, for example, comprise one cable 30 per finger portion 20. This allows each finger portion 20 to be controlled independently. Alternatively, the haptic glove 1 may comprise one cable 30 per finger phalanx of a user's hand. This may enable more accurate control of the shape of a user's finger allowed by the haptic glove 1 to provide haptic feedback. The haptic glove 1 may in general comprise any number of cables 30 per finger portion 20.

Shell for (partially) surrounding user's hand

Figs 2A and 2B schematically depict an embodiment of the base portion 10 and one finger portion 20 in combination with the cable 30 of the haptic glove 1. For illustrative purposes, Figs 2A and 2B depict a single finger portion 20 (for surrounding a user's index finger), but it will be appreciated that the haptic glove 1 may comprise a plurality of finger portions 20 for surrounding several or all of a user's fingers.

In Figs 2A and 2B, the base portion 10 and finger portion 20 take the form of a shell, in that the base portion 10 and finger portion 20 are configured to surround a user's hand and/or finger at least partially. The base portion 10 and/or finger portion 20 may thus be provided at least on the rear side and on the front side of a user's hand. The finger portion 20 is pivotally movable relative to the base portion 10. The finger portion 20 may pivot or bend relative to the base portion 10 at least in a direction orthogonal to a user's palm, i.e. in the up-down direction in Fig 2B.

Each finger portion 20 comprises one or more finger segments 22, for example a proximal finger segment 22a arranged next to the base portion 10, a distal finger segment 22c arranged away from the base portion 10, and a middle finger segment 22b arranged between the proximal finger segment 22a and the distal finger segment 22c. The embodiment of Fig. 2A and 2B depicts a finger portion 20 comprising three finger segments 22, but it will be appreciated that a different number of finger segments 22, may be provided. For example, a finger portion 20 for surrounding the thumb of a user's hand 2 may comprise two finger segments 22, e.g. a proximal finger segment 22a and a distal finger segment 22c. In an embodiment, the haptic glove 1 comprises four finger portions 20 with three finger segments 22, and one finger portion 20 with two finger segments 22.

Each finger segment 22 surrounds, in use, a respective phalanx of a respective finger of the user's hand 2. Each finger segment 22 may be shaped as a tube, although in general any shape that can be worn on a user's finger is suitable. The distal finger segment 22c may be shaped as a thimble.

As shown in Figs. 2A and 2B, the base portion 10 and finger portion 20 comprise a bearing 23a arranged between the base portion 10 and the finger portion 20 (in particular between the base portion 10 and the proximal finger segment 22a). The bearing 23a may be a pivot bearing. The bearing 23a allows bending of the finger portion 20 relative to the base portion 10. The finger portion 20 comprises further bearings 23b, 23c arranged between the finger segments 22. The further bearings 23b, 23c may be pivot bearings. The further bearings 23b, 23c allow bending of the finger segments 22 relative to each other. In the depicted embodiment, each of the bearings 23 comprises a plain bearing, i.e. a bearing in which two surfaces bear directly onto each other. Such a bearing is relatively simple to manufacture and compact. Flowever, in general, any other type of bearing, such as a roller bearing (comprising roller elements between the two bearing surfaces) or a flexure bearing (comprising flexible, deformable elements between the two bearing surfaces) may be provided in place of a plain bearing.

The base portion 10 and/or finger portion 20 may further comprise guide channels 18, 28. The guide channels 18, 28 are for guiding the cable 30, which is schematically depicted in dashed lines in Figs. 2A and 2B. If more than one cable 30 is provided per finger portion 20, then additional guide channels 18, 28 may be provided. The guide channels 28 may be provided on each of the finger segments 22 (as shown in Fig 2A) or on some, e.g. at least one, of the finger segments 22. The distal end of the cable 30 (i.e. the end of the cable that is arranged away from the base portion 10) is mechanically connected (fixed) to the distal end of the finger portion 20 (e.g. to the distal finger segment 22c). The proximal end of the cable 30 (i.e. the end of the cable 30 that is arranged next to the base portion 10) may extend to the base portion 10, e.g. to the cable control mechanism 100. Fixing the proximal end of the cable 30 in place constrains movement of the finger segments 22, in that the user's fingers are prevented from curling any further than the position of the finger segments 22 allows. Controlling movement of the proximal end of the cable 30 thus provides haptic feedback to a user's hand, simulating holding a virtual object, for example.

Although only one cable 30 is shown in Figs 2A and 2B, the haptic glove 1 may comprise multiple cables 30 per finger portion 20. For example, the haptic glove 1 may comprise a cable 30 for each finger segment 22, such that each cable 30 is connected at one end to a respective finger segment 22. This allows the relative position of each finger segment 22 to be more accurately controlled, and thus improve haptic feedback deliverable by the haptic glove 1.

The base portion 10 and each of the finger segments 22 may be rigid parts, improving the haptic feedback provided to a user. The base portion 10 and each of the finger segments 22 may be integrally formed, i.e. formed as a single part. This reduces the complexity of manufacturing. Each of the base portion 10 and the finger segments 22 may be formed by injection moulding, for example. The base portion 10 and the finger segments 22 may be formed from any material that provides the required structural integrity for providing a shell surrounding a user's hand 2, e.g. a hard plastic.

Finger portion formed from plurality of segments for conforming to user's finger

Figs 3A and 3B schematically depict an alternative embodiment of the base portion 10 and finger portion 20. Figures 3C to 3F depict certain aspects of the finger portion 20 of the haptic glove 1. Figures 4A-E depict further embodiments of the finger portion 20.

The base portion 10 may in essence correspond to the base portion 10 described with reference to Figs 2A and 2B. Flowever, the base portion 10 and finger portion 20 need not surround the user's hand 2, but may instead be provided at the back of the user's hand. For illustrative purposes, Figs 3A and 3B, as well as Fig 4A, depict a single finger portion 20, but it will be appreciated that the haptic glove 1 may comprise a plurality of finger portions 20, for example a finger portion 20 for each of a user's fingers or a finger portion 20 for a subset (e.g. for four) of a user's fingers.

Each finger portion 20 comprises a plurality of segments 22. Compared to the finger portion 20 of Figs 2A and 2B, the segments 22 of Figs 3 and 4 need not all surround a user's finger, but are provided at least at the back of a user's finger. Furthermore, the finger portion 20 of Figs 3 and 4 comprises a larger number of smaller segments. This allows the finger portion 20 to adapt to fingers of different lengths. The finger portion 20 may comprise a plurality of segments arranged to conform to the shape of a user's finger. The number of segments 22 in each finger portion 20 may be more than 3, preferably more than 5, further preferably more than 10, particularly preferably more than 20. The longitudinal extent of each segment 22, i.e. the extent of each segment in a direction along the chain of segments, may be less than 1cm, preferably less than 0.7cm, further preferably less than 0.5cm, particularly preferably less than 0.3cm. A larger number of segments, and a smaller extent of segments, allows the finger portion 20 to adapt to a wider range of different finger sizes.

Some or all of the segments 22 may be identical in structure. Figure 4C, for example, shows a finger portion 20 in which the majority of segments are identical. This may make manufacture of the finger portion cheaper and allow the finger portion to conform to a wide range of finger sized. The segments 22, or at least a portion of the segments 22, may be rigid.

In alternative embodiments, the segments 22 within a finger portion 20 may be shaped differently or have different extents along the finger portion 20. This is schematically shown in Figures 4B (in plan view) and 4C (as a side view). For example, segments that lie closer to an average user's finger joints may be shorter, with more segments being provided around the average user's finger joints. Segments that lie between an average user's finger joints may be larger, with fewer segments or only one segment being provided in regions lying between an average user's finger joints. So, for example, each finger portion 20 may comprise, arranged in sequence from the base portion 10, an alternating arrangement of i) a plurality of relatively smaller segments and ii) one or more relatively larger segments.

The segments 22 may be coupled to each other using a coupling element 23, which may act as a bearing 23 between segments 22. The coupling element 23 may allow the segments 22 to pivot relative to one another. The coupling element 23 may, for example, be a flexible tape or an elastomer to which each of the segments 22 is fixed, e.g. by gluing or any other appropriate method. The coupling element 23 may alternatively comprise individual hinges or flexible elements between adjacent segments 22. The coupling element 23 may alternatively comprise one or more cables or wires that allow relative pivotal motion between adjacent segments. Preferably, the coupling element 23 is an elongate part extending along the entire length of the finger portion 20.

Figs 3C and 4F schematically depicts one example of a finger segment 22. The segment 22 may comprise a curved surface 22s for arrangement on a user's finger, thus resembling a saddle sitting on a user's finger. The segments 22 may be generally triangular in shape (as shown in Figure 3C), with the cable 30 being provided at the apex of the segments 22 that is furthest apart from the curved surface 22s. Flowever, it will be appreciated that the segments 22 may have any other appropriate geometry, such as the rounded shape in Figure 4F. The segments 22 may be provided as blocks or cubes.

As shown in Figures 3C and 4F, the segments 22 may be hollow, optionally with reinforcing struts. This may reduce the weight of the segments 22 and the material requirements for producing the segments 22. Furthermore, the hollow areas may provide space for the cable 30 or some of the cables 30 (if multiple cables are provided). Alternatively, the segments 22 may be formed as solid bodies.

As shown in Figure 4E, each finger segment 22 may comprises a pair of protrusions 26a arranged to protrude towards, and at least in use be in direct contact with, an adjacent finger segment 22. Each protrusion 26a may comprise a pivoting point 26al about which the respective finger segment is pivotable relative to the adjacent finger segments. Each finger segment may further comprise a pair of depressions 26b or recesses 26b arranged to receive the pair of protrusions of an adjacent finger segment 22. This construction provides an accurate and reliably pivot point about which adjacent segments 22 may pivot. In general, however, other arrangements for allowing pivoting between adjacent segments, such as ball and socket arrangements, may also be used.

As depicted in Fig 3C, the coupling element 23 may comprise a pair of coupling cables 23. Figure 4E and 4F show the lumens provided for the coupling cables 23. The coupling cables 23 couple the segments 22 to each other and may provide pivot points about which two adjacent segments 22 may pivot relative to one another. The coupling cables 22 may be arranged on or towards the sides of a user's finger when in use. As such, the pivot points about which two adjacent segments 22 pivot may be closer to the joints of a user's finger, thereby achieving a more natural feel for the user.

Fig 3D schematically depicts a plan view of a series of segments 22 of Fig 3C, coupled together using coupling cables 23. As depicted, the coupling cables 23 may be connected at a point to the base portion 10. This allows the finger portion 20 to move laterally, i.e. in a plane parallel to a user's palm, relative to the base portion 10. Movement in this lateral direction may be allowed by the coupling between base portion 10 and finger portion 20. Not constraining such lateral motion provides additional freedom of movement to a user's fingers, thus achieving a more natural feel for a user wearing the haptic glove 1.

As shown in Figs 3A and 3B, at least some of the segments 22, optionally all of the segments, may be configured to surround a user's finger. More generally, at least some of the segments 22 may comprise a palmar portion 22' configured to engage the palmer side of a user's fingers. The palmar portion 22' is coupled to the finger segment 22 and may transfer a force from the user's finger to the finger portion 20 and cable 30. Motion of a user's finger may be selectively constrained via these segments 22', so as to provide haptic feedback to the user.

Figs 3E and 3F schematically depict examples of the segments with a palmar portion 22'. The palmar portions 22' may be connected or coupled to any of the segments 22 described in relation to Fig 3C or 4F. The palmar portion 22' may optionally be formed from sheet material, as depicted in Figs 3E and 3F. For example, the palmar portion may be formed by providing a strip of sheet material, such as sheet metal, and providing cut-outs between adjacent bottom portions 22', such that adjacent bottom portions 22' are connected by a flexible joint portion 23' at either end. The palmar portions may thus comprise a plurality of cut-outs or slits extending in a direction orthogonal to the longitudinal extent of a user's finger.

Alternatively, the palmar portions 22' may comprise rigid parts that are coupled to the segments. This allows further elements, such as haptic assemblies for providing localized haptic feedback, to be provided on the palmar portions 22.

In general the palmar portion 22' may be connected to the segments 22 by any suitable connection method, such as gluing or by providing straps. Cable control assembly 100 for providing haptic feedback

As described above, controlling (in particular constraining) movement of the cable 30 (in particular of the proximal portion of the cable 30) may be used to provide haptic feedback to a user's hand.

The figures described below schematically depict various aspects of the cable control assembly 100. The cable control assembly 100 may comprise or embody one or more of a retraction mechanism 110 for retracting the cable 30, a locking mechanism 120a for locking the proximal portion of the cable 30 in place, a brake mechanism 120b for braking movement of the proximal portion of the cable 30a, and a spring mechanism 120c for selectively applying a spring force to the proximal portion of the cable 30, in particular along the cable 30. A respective part of the cable control assembly 100 may be provided individually for each cable 30, or multiple cables 30 (e.g. all cables coupled to a finger portion 20) may be controlled by a single part of the cable control assembly 100, for example by coupling multiple cables using the multi-cable coupling 170. Described below are examples of parts of the cable control assembly 100 that achieve one or more of these functions.

Multi-cable coupling 170

As explained above, the haptic glove 1 may in some embodiments comprise more than one cable 30 per finger portion 20, for example one cable 30 per phalanx of a user's hand. The shape of the finger portion 20 can thus be more accurately controlled compared to providing a single cable 30 per finger portion 20, enabling improved haptic feedback.

In general, each cable 30 of the multiple cables 30 per finger portion 20 may be controlled independently, either within the same cable control assembly 100 or by different cable control assemblies 100.

The multiple cables 30 coupled to a finger portion 20 may move by proportional amounts. For example, with reference to Figure 2B, a first cable 30 coupled a first finger segment 22 of the finger portion 20 may move by a first amount, and a second cable 30 coupled to a second finger segment 22 of the finger portion 20 may move by a second amount that is proportional to the first amount. When three cables are provided, a third cable 30 coupled to a third finger segment 22 of the finger portion 20 may move by a third amount that is proportional to the first amount. A cable 30 coupled to a relatively distal finger segment 22 may be allowed to move by a larger amount than a cable 30 coupled to a relatively proximal finger segment 22 (relative to the base portion 10). This allows natural curling of a user's finger.

The multiple cables 30 may be coupled to one another to enable such proportional movement. This allows the multiple cables 30 per finger portion 20 to be controlled simultaneously. Control is thus simplified, because a single cable control assembly 100 may be used to control multiple cables 30.

Figures 5A and 5B schematically show a plan view and a side view of one embodiment of a multi cable coupling 170 for coupling multiple cables 30 together. In Figures 5A and 5B, the multi-cable coupling is in the form of a reel 175, in particular a multi-diameter reel 175. The multi-diameter reel 175 is, e.g., a rotatable drum or cylinder comprising portions 175A-C of multiple diameters. The cables 30 are wound on the reel 175.

The multi-diameter reel 175 comprises portions 175A-C with different diameters. Each portion 175A-C may be a cylinder or be considered a reel by itself. Different cables 30 are wound on portions of the reel with different diameters. The different cables 30 may be cables coupled to different finger segments 22 of the same finger portion 20, and so may be proportionally moved relative to each other. For example, a cable 30 coupled to a relatively distal finger segment 22 of the finger portion 20 (relative to the multi-diameter reel) may be wound on a relatively larger diameter portion 175C of the reel. A cable 30 coupled to a relatively proximal finger segment 22 of the finger portion 20 (relative to the multi-diameter reel) may be wound on a relatively smaller diameter portion 175A of the reel. This allows the cables 30 coupled to different finger segments 22 of the finger portion 20 to move proportionally, enabling the finger portion to allow a natural curling motion of a user's finger while simplifying control compared to a situation in which each cable 30 is controlled independently.

So, the portions of the reel 175 have different diameters, and allow for different movement of the different cables 30 relative to the base portion 10. Upon bending of a finger portion, for example, the proximal phalanx may bend less than the middle phalanx, which is turn bends less than the distal phalanx. As such, the cable 30 connected to the distal phalanx may move more relative to the base portion 10 than the cable connected to the middle phalanx and the cable connected to the proximal phalanx. The multi-cable coupling may apply gearing to the movement of the cables 30 relative to the base portion 10. Another advantage of providing a reel on which the cable 30 is wound that relatively large cable movement is enabled within a relatively compact space. The excess cable length is neatly wound on the reel. In general, a single diameter reel may be provided to achieve these advantages without implementing multi-cable control 170.

Constrain mechanism 120

Figure 6 shows an example of a constrain mechanism 120 in the form of a locking mechanism 120a. The constrain mechanism 120 may be engaged by moving an actuating part 220, which is coupled to a locking part 124. The actuating part 220 may be moved by an SMA wire or any other actuating component, for example. The actuating part 220 may form part of a controllable latch. Upon moving the actuating part 220, the locking part 124 engages the reel 102 so as to prevent rotation of the reel. As such, movement of the proximal portion of the cables 30 is prevented, and movement of the corresponding finger portion 30 relative to the base portion 10 is prevented.

In Figure 6, the locking part 124 comprises teeth for engaging corresponding teeth on the reel. A resilient element, such as a spring 221, may be provided between locking part 124 and actuating part 220 to avoid damage to the teeth upon engagement, for example in situations in which they engage when the tips of the teeth meet.

The locking mechanism 120a of Figure 6 may instead be provided as a brake mechanism by replacing the teeth of the locking part 124 and reel with friction surfaces that engage each other. A frictional force may then be selectively applied to the reel 175, and so to the cable 30.

The locking mechanism 120a of Figure 6 may instead be provided as a brake mechanism by replacing the teeth of the locking part 124 and reel with friction surfaces that engage each other. A frictional force may then be selectively applied to the reel 175, and so to the cable 30.

As a further alternative, an actuating component, such as an SMA wire, may selectively couple a biasing element, such as a spring, to the reel 175. So, the spring mechanism 120c may be implemented.

Retraction mechanism 110 The cable control mechanism 100 may comprise a retraction mechanism 110 for retracting the cable upon unbending of the finger portions. The retraction mechanism 110 may be embodied by any resilient element permanently coupled to the movable part 102 and capable of retracting the cable 30. Preferably, the resilient element is capable of retracting the cable 30 over the entire movement range of the cable 30.

The retraction mechanism may be embodied by a torsion spring, for example for applying a torque to the reel 175 for retracting the cable 30. The retraction mechanism 110 may alternatively be embodied by a tension or compression spring, for example coupled to a movable part in the form of a rack 102" or the coupling cable 102'. The retraction mechanism 110 may also act directly on the cable, for example by a spring connected directly to the proximal end of the cable 30.

Additional features

The constrain mechanism 120, along with respective cables 30, allow movement of the finger portions 20 relative to the base portion 10 to be constrained. In some embodiments, additional features for providing haptic feedback and/or tracking movement of a user's fingers may be provided. Such additional features are explained with reference to Figs. 7 to 10.

As shown in Fig. 11, the haptic glove 1 may comprise one or more SMA wires 210. Each SMA wire 210is connected between the base portion 10 and a finger portion 20. The SMA wires 210 may be used to determine the position of the finger portion 20 (or finger segments 22) relative to the base portion 10 and/or to provide haptic feedback to the user's hand.

The SMA wires 210 are arranged and extend along the finger portions 10, i.e. in parallel with the tendons in a user's hand. In a preferable embodiment, the haptic glove 1 comprises both SMA wires 210 that are connected between the base portion 10 and the finger portions 20 on the rear side of the haptic glove 1, and SMA wire 210 that are connected between the base portion 10 and the finger portions 22 on the palm side of the haptic glove 1. When a user curls a finger, the SMA wire 210 on the rear side of the haptic glove 1 will extend, while the SMA wire 210 on the palm side of the haptic glove 1 may contract. When a user extends a finger (from a curled position), the SMA wire 210 on the rear side of the haptic glove 1 may contract, while the SMA wire 210 on the palm side of the haptic glove will extend. The haptic glove 1 may comprise a controller (not shown) that provides a signal to the SMA wires 210. The controller may measure an electrical characteristic, such as the resistance, of the SMA wires 210. The length of an SMA wire 210 is a function of the resistance of the SMA wire 210. So, measuring the resistance of each SMA wire 210 allows the length of each SMA wire 210 to be determined. The length, or change of length, of the combination of SMA wires 210 connected to a finger portion 20 allows the shape of the finger portion 20 to be determined. So, the controller may determine a measure of the position of the finger portion 20 relative to the base portion 10 based on the measured electrical characteristic. Based on the shape or position of the finger portion 20, the controller may provide haptic feedback, for example by controlling the constrain mechanism 120 of any one the preceding embodiments.

In some embodiments, the controller may further apply a control signal, such as a pulse width modulated (PWM) signal, to the SMA wires 210. Applying the control signal may heat the SMA wires 210, so as to contract the SMA wires 210. The SMA wires 210 may thus be used to providing haptic feedback to the user's hand.

In a preferable embodiment, the cables 30 provide electrical connections to the ends of the SMA wires 210 that are connected to the finger portion 20. This ensures that no additional electrical connections need to be routed from the base portion 10 towards the distal ends of the finger portions 20.

Figures 7A-C depict an embodiment in which SMA wires 210 are connected between the distal finger segment 22 and the base portion 20. In addition, SMA wires 210 may be connected between the proximal finger segment 22 and the base portion 10, and/or between the middle finger segment 22 and the base portion 10. Providing these additional SMA wires 210 may allow the shape of the finger portion 10 to be determined more accurately, and/or allow more complex haptic feedback to be delivered to a user's hand.

As shown in Fig 7A-C, the finger portions 20 may comprising a plurality of guide channels 211 for guiding the SMA wires 210 between the base portion 10 and the respective finger portion 20. The guide channels 211 may be integrally formed in the finger portion 20. Alternatively, the guide channels 211 may be formed separately from the finger portion 20. As further shown in Figs 7B and 7C, the haptic glove 1 may comprise an inner glove 8. The inner glove 8 is configured to be in contact with the user's hand in use. The inner glove 8 may provide more comfort than the rigid finger segments 22 and base portion 20, and in particular be more deformable. The SMA wires 210 may be arranged between the inner glove 8 and the finger segments 22 and base portion 20.

Localized haptic feedback

As further shown in Figs. 7, the haptic glove 1 may further comprise haptic assemblies 200, such as SMA haptic assemblies. The haptic assemblies 200 may be locally arranged at select locations on the finger portions 20 and/or base portion 10. In contrast to the constrain mechanisms 120 or the SMA wires 210 described above, the SMA haptic assemblies 200 may provide highly localized haptic feedback to a user's hand.

The SMA haptic assemblies 200 may be arranged to provide haptic feedback to portion of a user's finger that are particularly susceptible to haptic feedback. For example, the SMA haptic assemblies 200may be arranged to provide haptic feedback to the fingertips of a user's hand. In some embodiments, an SMA haptic assembly 200is provided for each phalanx of a user's fingers. Indeed, multiple SMA haptic assemblies 200 may be provided to form an array on the palmar portion of a finger segment 22. The SMA haptic assemblies 200may, for example, be arranged in a one or two dimensional array on each finger segment 22. Arranging the SMA haptic assemblies in such arrays allows more detailed haptic feedback to be provided to the user, for example imitating particular surface structures of a virtual object that is simulated as being held by the user.

Figures 9a-c depict various embodiments of one or two-dimensional arrays of SMA haptic assemblies 200. The haptic assemblies may be provided on a fingertip, for example. The arrangement of Figure 9a comprises a centre SMA haptic assembly surrounded by four edge SMA haptic assemblies. Such an SMA haptic assembly may be particularly suitable to provide localized feedback, allowing various haptic sensations to be provided to a user. Figure 9b depicts an example of a one-dimensional array of SMA haptic assemblies. Such an array may be easier to provide. Figure 9c depicts another example of a two-dimensional array of SMA haptic assemblies. The depicted two-dimensional array is a hexagonal array of SMA haptic assemblies, although in general any other packing (e.g. square, rectangular) may be suitable. In preferred embodiments, the SMA haptic assemblies 200 comprise SMA haptic waves, such as the haptic waves disclosed in PCT/GB2020/053252 or PCT/GB2021/050159, which are herein incorporated by reference. So, the SMA haptic assembly 200 may comprise a first part 41 and a second part 42 that are movable relative to each other along a haptic movement axis H. The first part 41 may be fixed relative to the finger segment 22, and the second part 42 may be fixed relative to the inner glove 8. The SMA haptic assembly 40 further comprises an SMA wire 43, each of the ends of the SMA wire 43 being connected to the first part 41 or second part 41. The first part 41 comprises at least one contact portion 41a making contact with the SMA wire on a first side of the SMA wire along the movement axis, the second part 42 comprises at least one contact portion 42a making contact with the SMA wire 46 on a second side of the SMA wire 46 along the movement axis H, opposite to the first side. The at least one contact portion of the first part 41 and the at least one contact portion of the second part 42 are relatively positioned so as to guide the SMA wire along a tortuous path such that the first and second parts are driven in opposite directions along the haptic movement axis H on contraction of the SMA wire 46.

A particular preferable embodiment of an SMA haptic wave that may be used in the haptic glove 1 is shown in Figs. 8A and 8B. Fig. 8A shows a side view of the SMA haptic wave. Fig. 8B shows an end view of the haptic wave. As shown, the first part 41 and the second part 42 of the SMA haptic assembly each comprise substantially flat body portions that are in contact with one another before contraction of the SMA wire 46. The first and second parts each further comprise at least one protrusion that protrudes from a side of the body portion along the movement axis H, the contact portion of the first and second part being provided on the respective protrusion.

In the depicted embodiment, the SMA haptic assembly comprises a second SMA wire. The first and second parts of the SMA haptic assembly each further comprise at least another protrusion that protrudes from another side of the body portion along the movement axis. The other protrusions of the first and second parts comprise contact portions making contact with the second SMA wire so as to guide the SMA wire along a tortuous path such that the first and second parts are driven in opposite directions along the haptic movement axis on contraction of the second SMA wire.

An advantage of the SMA haptic wave of Fig. 8 is that the provision of the substantially flat body portions makes the SMA haptic assembly particularly flexible. The SMA haptic assembly may thus bend more easily than existing SMA haptic assemblies. This allows the SMA haptic assembly to easily conform to the shape of the finger portions of the haptic glove 1, as schematically depicted in Fig. 7B.

Although the SMA haptic assemblies 200 have been described in relation to SMA haptic waves, any other SMA haptic assemblies 200 may be used. Any SMA haptic assembly 200 capable of providing localized haptic feedback is suitable for inclusion in the haptic glove.

While the embodiments above have been described in relation to a haptic glove, it will be appreciated that the teachings of the present invention may also be applied to other haptic garments or wearable articles, as well as other mechanisms. There is thus generally disclosed a wearable article, or an actuator assembly, comprising: a shell comprising a base portion and one of more pivoting portions extending from the base portion, wherein each pivoting portion is pivotally movable relative to the base portion, and one or more cables, each comprising a distal end connected to a respective pivoting portion and a proximal end extending towards the base portion; and wherein the wearable article, or actuator assembly, further comprises one or more constrain mechanisms for constraining movement of the proximal end of a respective cable with respect to the base portion, thereby constraining bending of a respective pivoting portion relative to the base portion.

Joystick

Optionally, further features may be provided on the haptic glove to improve the functionality of the haptic glove. In some embodiments, a joystick 300 is provided on a finger portion 20, as schematically depicted in Figure 10. The joystick may be provided to allow a user to navigate a virtual world, for example.

In other embodiments, a virtual joystick may be provided. In such embodiments, no physical joystick need be provided. Instead, the change in position of a thumb portion of the haptic glove may be determined so as to determine the position of the virtual joystick. In further embodiments, a user may use any other gestures to navigate a virtual world.

The term 'shape memory alloy (SMA) wire' may refer to any element comprising SMA. The SMA wire may have any shape that is suitable for the purposes described herein. The SMA wire may be elongate and may have a round cross section or any other shape cross section. The cross section may vary along the length of the SMA wire. It is also possible that the length of the SMA wire (however defined) may be similar to one or more of its other dimensions. The SMA wire may be pliant or, in other words, flexible. In some examples, when connected in a straight line between two elements, the SMA wire can apply only a tensile force which urges the two elements together. In other examples, the SMA wire may be bent around an element and can apply a force to the element as the SMA wire tends to straighten under tension. The SMA wire may be beam-like or rigid and may be able to apply different (e.g. non-tensile) forces to elements. The SMA wire may or may not include material(s) and/or component(s) that are not SMA. For example, the SMA wire may comprise a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term 'SMA wire' may refer to any configuration of SMA wire acting as a single actuating element which, for example, can be individually controlled to produce a force on an element. For example, the SMA wire may comprise two or more portions of SMA wire that are arranged mechanically in parallel and/or in series. In some arrangements, the SMA wire may be part of a larger piece of SMA wire. Such a larger piece of SMA wire might comprise two or more parts that are individually controllable, thereby forming two or more SMA wires.

Whilst the embodiments above have described actuator assemblies which use SMA wires, the skilled person will appreciate that the features of the bearing arrangements and the flexures described can be readily used with other forms of actuator components. For example, each actuator component may be a voice coil motor (VCM) actuator, but other types of actuator are possible, for example a piezoelectric actuator, a radial motor or others.

Further aspects of the present invention are set out in the following clauses:

1. Haptic glove for providing haptic feedback to a user's hand, the haptic glove comprising: a main body comprising a base portion and one of more finger portions extending from the base portion, wherein each finger portion is pivotally movable relative to the base portion, and one or more cables, each comprising a distal end connected to a respective finger portion and a proximal end extending towards the base portion; and wherein the haptic glove further comprises one or more constrain mechanisms for constraining movement of the proximal end of a respective cable with respect to the base portion, thereby constraining bending of a respective finger portion relative to the base portion.

2. The haptic glove of clause 1, wherein the main body comprises a plurality of finger portions, and wherein each finger portion comprises a plurality of finger segments.

3. The haptic glove of clause 1 or 2, comprising a plurality of cables and a plurality of respective constrain mechanisms for each finger portion, each cable being connected at one end to a different finger segment of the finger portion. 4. The haptic glove of any preceding clause, wherein each cable and the main body form a force-locked loop upon constraining movement of the proximal end of a respective cable with respect to the base portion, with the cable in tension and the shell in compression, thereby constraining bending of a respective finger portion relative to the base portion.

5. The haptic glove of any preceding clause, wherein the main body comprises bearings arranged between the base portion and each finger portion, and bearings arranged between adjacent finger segments.

6. The haptic glove of clause 5, wherein the bearings are arranged to, in use, be on both sides of a finger of the user's hand.

7. The haptic glove of clause 5 or 6, wherein the bearings are plain bearings.

8. The haptic glove of any preceding clause, wherein the main body comprises a shell configured, in use, to at least partially surround a user's hand.

8a The haptic glove of clause 8, wherein each finger portion and each finger segment is configured, in use, to entirely surround a finger of the user's hand.

8b. The haptic glove of any one of clauses 1 to 7, wherein each finger portion comprises a plurality of finger segments, wherein the number of finger segments in each finger portion is greater than 3, preferably greater than 5, further preferably greater than 10 and/or wherein the extent of each finger segment between adjacent finger segments is less than 1cm, preferably less than 0.5cm.

9. The haptic glove of any preceding clause, wherein the base portion and each finger portion is integrally formed, preferably by injection molding.

10. The haptic glove of any preceding clause, wherein the base portion and/or the one or more finger portions comprise integral guide channels for guiding the cable from the finger portion towards the base portion;

11. The haptic glove of any preceding clause, wherein each constrain mechanism comprises: a movable part that is movable relative to the base portion, wherein the movable part is arranged at the proximal end of the respective cable; an intermediary part, and an actuator component arranged to move the intermediary part into or out of engagement with the movable part and/or the base portion so as to constrain movement of the movable part relative to the base portion.

12. The haptic glove of clause 11, wherein the movable part is movable relative to the base portion along a movement axis that is substantially aligned with the proximal portion of the cable, and wherein the intermediary part is configured to constrain movement of the movable part relative to the support structure along the movement axis. 13. The haptic glove of clause 11 or 12, wherein the actuator component is arranged to move the intermediary part in a direction that is angled, preferably perpendicular, relative to the movement axis.

14. The haptic glove of any one of clauses 11 to 13, wherein the intermediary part and the movable part comprise engagement surfaces for engaging each other, wherein the engagement surfaces are configured, on engagement, to constrain sliding between the intermediary part and the movable part.

15. The haptic glove of clause 14, wherein each engagement surface comprises a plurality of teeth.

16. The haptic glove of any preceding clause, wherein the actuator component comprises an SMA wire.

17. The haptic glove of clause 16, wherein the two ends of the SMA wire are fixed relative to the base portion, and wherein the SMA wire bends around a contact portion that is in contact with the intermediary part, thereby forming two SMA portions on either side of the contact portion, the two SMA portions being angled relative to each other.

18. The haptic glove of clause 16, wherein the SMA wire is connected between the intermediary part and the support structure.

19. The haptic glove of clause 18, wherein the intermediary part comprises a sliding surface that slidingly engages base portion, the sliding surface being angled relative to the movement axis along which the movable part is movable relative to the support structure, wherein the SMA wire is arranged, on contraction, to move the intermediary part along the sliding surface.

20. The haptic glove of any one of clauses 11 to 19, further comprising a second movable part that is movable relative to the support structure, a second intermediary part, and a resilient element connected between the movable part and the second movable part.

21. The haptic glove of clause 20, further comprising a second actuator component arranged, on actuation, to move the second intermediary part into or out of engagement with the second movable part or the base portion, thereby constraining movement of the second movable part relative to the base portion.

22. The haptic glove of clause 20, further comprising a second resilient element connected between the intermediary part and the second intermediary part, wherein the actuator component is configured to be actuatable between three different actuation positions, wherein in the first actuation position, neither of the intermediary part and second intermediary part engage the respective movable part and second movable part; in the second actuation position, the second intermediary part engages the second movable part and the intermediary part does not engage the movable part; and in the third actuation position, both the intermediary part and second intermediary part engage the respective movable part and second movable part.

23. The haptic glove of any preceding clause, further comprising a biasing element configured to bias the intermediary part out of or into engagement with the movable part or base portion, wherein the actuator component is arranged, on actuation, to oppose the biasing force of the biasing element.

24. The haptic glove of any preceding clause, further comprising at least one SMA wire connected between the base portion and the distal end of the finger portion.

25. The haptic glove of clause 24, wherein the at least one SMA wire comprises an SMA wire that is connected between the base portion and the distal end of the finger portion on the rear side of the shell, and another SMA wire that is connected between the base portion and the distal end of the finger portion on the palm side of the haptic glove.

26. The haptic glove of clause 24 or 25, further comprising a controller configured to provide a signal to the at least one SMA wire.

27. The haptic glove of clause 26, wherein the controller is configured to measure an electrical characteristic of the at least one SMA wire and to determine a measure of the amount of pivotal movement of the distal end of the finger portion relative to the support structure based on the measured electrical characteristic.

28. The haptic glove of clause 26 or 27, wherein the controller is configured to apply a control signal to the at least one SMA wire so as to contract the SMA wire, thereby providing haptic feedback to the user's hand.

29. The haptic glove of any one of clauses 24 to 28, comprising a plurality of SMA wires, each connected between the base portion and a respective finger segment.

30. The haptic glove of any one of clauses 24 to 29, further comprising a plurality of guide channels for guiding the at least one SMA wire between the base portion and the respective finger portion, the guide channel being integrally formed in the shell.

31. The haptic glove of any one of clauses 24 to 30, comprising an inner glove configured to be in contact with the user's hand, wherein the at least one SMA wire is arranged between the inner glove and the shell.

32. The haptic glove of any preceding clause, further comprising an SMA haptic assembly locally arranged at the distal end of the finger portion. 33. The haptic glove of clause 32, wherein the SMA haptic assembly comprises first and second parts that are movable relative to each other along a haptic movement axis; and an SMA wire, each of the ends of the SMA wire being connected to the first part or second part, wherein the first part comprises at least one contact portion making contact with the SMA wire on a first side of the SMA wire along the movement axis, the second part comprises at least one contact portion making contact with the SMA wire on a second side of the SMA wire along the movement axis, opposite to the first side, the at least one contact portion of the first part and the at least one contact portion of the second part being relatively positioned so as to guide the SMA wire along a tortuous path such that the first and second parts are driven in opposite directions along the haptic movement axis on contraction of the SMA wire, and the at least one contact portion of one of the first and second parts is formed from sheet material that is shaped to guide the path of the SMA wire in contact therewith.

34. The haptic glove of clause 33, wherein the first and second parts of the SMA haptic assembly each comprise substantially flat body portions that are in contact with one another before contraction of the SMA wire.

35. The haptic glove of clause 34, wherein the first and second parts of the SMA haptic assembly each further comprise at least one protrusion that protrudes from a side of the body portion along the movement axis, the contact portion of the first and second part being provided on the respective protrusion.

36. The haptic glove of clause 34 or 35, wherein the SMA haptic assembly comprises a second SMA wire, and wherein the first and second parts of the SMA haptic assembly each further comprise at least another protrusion that protrudes from another side of the body portion along the movement axis, the other protrusions of the first and second parts comprising contact portions making contact with the second SMA wire so as to guide the SMA wire along a tortuous path such that the first and second parts are driven in opposite directions along the haptic movement axis on contraction of the second SMA wire.

37. The haptic glove of any one of clauses 32 to 36, wherein the SMA haptic assembly is flexible so as to conform to the shape of the finger portions of the haptic glove.

38. The haptic glove of any one of clauses 32 to 37, further comprising a controller configured to provide a signal to the SMA haptic assembly.

39. The haptic glove of clause 38, wherein the controller is configured to measure an electrical characteristic of at least one SMA wire of the SMA haptic assembly, and to determine a measure of the force acting on the SMA haptic assembly based on the measured electrical characteristic of the at least one SMA wire.

40. The haptic glove of clause 38 or 39, wherein the controller is configured to apply a control signal to at least one SMA wire of the SMA haptic assembly so as to contract the SMA wire, thereby providing haptic feedback to the user's hand.

41. The haptic glove of any one of clauses 32 to 40, and clause 2, comprising: a plurality of SMA haptic assemblies, each provided on a respective finger segment. 42. The haptic glove of any one of clause 32 to 41, comprising an inner glove configured to be in contact with the user's hand, wherein the at least one SMA haptic assembly is arranged between the inner glove and the shell.

43. The haptic glove of clause 42, wherein the inner glove is more flexible than the shell, such that the at least one SMA haptic assembly preferentially transmits haptic feedback via the inner glove to the user's hand.