TECHNICAL FIELD

The present invention relates to a finger for a robotic gripper for picking up an object, such as a plate or a bowl.

BACKGROUND

Robot devices comprising robotic grippers (or hands) for picking up and handling objects are known. Typically, a robotic gripper may include multiple fingers which can be moved relative to one another, in order to grip (or hold) an object between the fingers. For example, in a so-called parallel gripper, at least two fingers are movable relative to each other along an axis. In this manner, the two fingers can be moved towards each other to grip an object between the fingers, and the two fingers can be moved away from each other in order to release the object. Other types of grippers may mimic the human hand more closely, for instance including multiple articulated fingers which may enable more complex object manipulations.

A robotic gripper may be combined with other robotic elements, such as a robotic arm or other type of actuator, so that the robotic gripper can be moved around. In this manner, the robotic gripper can be used to pick up and set down objects at different locations.

The present invention has been devised in light of the above considerations.

SUMMARY

At its most general, the present invention provides a finger for a robotic gripper, the finger being shaped to grip the edge of an object. In particular, the finger includes a gap arranged to fit around the edge of the object, whereby the edge of the object is held in the gap when the finger is pivoted relative to the object. This may enable the robotic gripper to pick up an object such as a plate, which would otherwise be difficult to pick up due to its shape and mass.

In a first aspect, the present invention provides a finger for a robotic gripper for picking up an object, the finger comprising a first member and a second member, wherein a gap is formed between the first member and the second member, the gap being configured to receive an edge of an object; wherein the first member is configured to contact a lower surface of the edge of the object when the edge of the object is received in the gap; and wherein the second member is configured to contact an upper surface of the edge of the object when the finger is pivoted relative to the object, such that the edge of the object is gripped between the first member and the second member.

Accordingly, when the edge of the object is inserted into the gap, the edge of the object can be gripped between the first member and the second member by pivoting the finger relative to the object. The finger thus provides a simple mechanism for gripping the edge of an object, e.g. so that the object can be picked up and manipulated by a gripper including the finger. In particular, the finger itself does not require any moving parts to grip the edge of the object, as the edge of the object is gripped as a result of the shape of the gap and a pivoting motion of the finger. Thus, for example, the finger does not require movable jaws in order to grip the edge of the object, thus simplifying construction of the finger and facilitating its integration with existing robotic grippers.

The finger of the invention is particularly suited to use with an object having a lip or rim around its edge, as the lip or rim may provide a convenient location for holding the object. Thus, the gap between the first member and the second member may be configured to receive an edge of a lip or rim of the object.

In some cases, the object may be a tableware (e.g. dishware) item for holding food. For example, the object may be a plate, a platter, a dish, a tray, a bowl, or the like.

The inventors have found that tableware items such as plates can be particularly difficult to pick up and hold with a robotic gripper, due to their large mass and size as well as their generally flat structure. When a plate is flat on a surface it may be particularly difficult to grasp with a conventional robotic gripper. Various known solutions for gripping plates exist, however they often present drawbacks. For example, the gripper may be made large enough to span a diameter of the plate, however such a large gripper may be heavy and difficult to manipulate with a robotic arm. As another example, a gripper using pinchers with movable jaws can be used to grip the edge of the plate, however this increases complexity and cost of the gripper. Suction-based grippers capable of picking up plates are also known, however these can be noisy as well as expensive.

In contrast, the finger of the invention can enable a robotic gripper to pick up difficult objects such as plates, without having to otherwise modify the gripper or use additional systems such as a suction system or movable jaws or pinchers. For instance, an existing robotic gripper can be retro-fitted with a finger according to the invention to enable it to pick up objects such as plates.

The finger of the invention is adapted for use with a robotic gripper. Thus, the finger may comprise an attachment region for attaching (e.g. mounting) the finger on a robotic gripper. In some cases, the finger may form part of a robotic gripper.

The first member and the second member may be arranged to extend away from the robotic gripper when the finger is attached to a robotic gripper, e.g. the first member and the second member may extend away from the attachment region of the finger. The first member and the second member may correspond to respective parts of the finger. In some cases, the finger including the first member and the second member may be integrally formed as a single part. In other cases, the first member and the second member may be formed as separate parts which are connected together.

The gap between the first member is configured to receive an edge of the object. In other words, a shape of the gap is arranged so that the edge of the object can be inserted into the gap. Thus, for example, a width of the gap may be equal to or greater than a thickness of the edge of the object, to enable insertion of the edge of the object into the gap. The shape and size of the gap may be specifically adapted to an object with which the finger is to be used.

The gap may, for example, be in the form of a groove, channel, or opening between the first member and the second member.

Herein, the edge of the object may refer to an edge portion or an edge region. The edge of the object may be located at an extremity or outer portion of the object. For example, the edge may be on a rim or lip of the object.

In use, the finger is approached towards the edge of the object, to insert the edge of the object into the groove. In this position, the first member may be located below the edge of the object whilst the second member may be located above the edge of the object. Then, when the finger is pivoted relative to the object, the first member contacts the lower surface of the edge whilst the second member contacts the upper surface of the edge of the object. The pivoting motion of the finger may be in a plane (direction) substantially normal to a surface on which the object rests. Thus, as a result of the pivoting motion, the edge of the object may be gripped between the first member and the second member, enabling the object to be picked up. In particular, as the centre of mass of the object will be spaced away from its edge (and hence from the finger), the gravitational force acting on the object’s centre of mass will tend to wedge the edge of the object between the first and second members when the finger is lifted upwards, such that the edge of the object is effectively gripped by the finger. Accordingly, an object such as a plate can be picked up with the finger of the invention. In particular, the finger of the invention may enable a plate to be picked up when it is laying flat on a surface, which can be challenging with known gripper mechanisms. To release the edge of the object, the object can be set onto a surface and the finger pivoted in an opposite direction to release the grip on the edge of the plate.

Where the object is in a stack of objects, the first member may be configured to fit between the lower surface of the edge of the object and an upper surface of an edge of a second, underlying object when the edge of the object is received in the gap. In this manner, the finger can be used to pick up the object from a stack of objects. In particular, this may enable the finger to pick up the topmost object from a stack of objects, by fitting the first member between the edge of the topmost object and the underlying object. For instance, the object may be a stackable object which is in (e.g. at the top of) a stack of identical objects. As an example, the object may be a tableware item such as a plate which is in (e.g. at the top of) a stack of tableware items.

The first member may be configured to fit between the lower surface of the edge of the object and the upper surface of the edge of the underlying object by arranging a thickness of the first member to be less than a distance between the lower surface of the edge of the object and the upper surface of the edge of the underlying object. In this manner, the edge of the topmost object in the stack can be gripped between the first member and the second member, so that the topmost object can be lifted off the stack (or placed on top of the stack). Thus, the thickness of the first member may be specifically adapted to a stackable item with which the finger is designed to be used. As an example, the thickness of the first member may be between about 1 mm and 5 mm. The thickness of the first member may be a maximum thickness of the first member.

A thickness of the first member may be equal to or less than a minimum width of the gap. This may facilitate lifting the object from a stack of objects, in line with the discussion above. In particular, making the thickness of the first member equal to or less than a minimum with of the gap may serve to ensure that the first member can fit between the edges of the topmost object and the underlying object in a stack of objects. Indeed, the minimum width of the gap may have a similar size to a thickness of the edge of the object (so that the edge can fit in the gap). Typically, the distance between the edges of stacked objects such as plates may be at least as large as the thickness of the edge of the object, so that the first member can reliably fit between the edges of the stacked objects.

Herein, the thickness of the first member may refer to a thickness of the first member in a direction normal to an edge of the first member that defines an edge of the gap-

A relative position of the first member and the second member is fixed. In other words, the first member and the second member may not be movable relative to each other, e.g. in contrast to mechanical jaws or pinchers. Thus, as discussed above, gripping of the edge of the object may be entirely the result of the shape of the first and second members and a pivoting/lifting motion of the finger. In this manner, the finger itself may be a passive (e.g. unpowered) component. In particular, the finger may not have any movable parts, with motion of the finger being controlled by a robotic gripper and/or robotic arm to which it is attached. This may facilitate integration of the finger into a robotic gripper, as there may be no need to connect the finger to any power source or controller.

The second member may comprise a protrusion that extends in the gap towards the first member, the protrusion being configured to contact the upper surface of the edge of the object when the finger is pivoted relative to the object. This may serve to improve a strength of the finger’s grip on the edge of the object and reduce a risk of slippage of the edge of the object in the gap, by providing a defined contact point between the second member and the edge of the object. The protrusion may also facilitate the second member coming into contact with the upper surface of the edge of the object when the finger is pivoted relative to the object, and may result in a smaller pivoting angle being needed to grip the edge of the plate.

In addition, or alternatively, the protrusion may enable a significantly larger range of movement and/or orientations of the finger while the finger is gripping the edge of the object. In particular, in the absence of the protrusion the range of movement and/or orientations of the finger while the finger is gripping the edge of the object may be limited because there may be a risk that the edge of the object will fall out of the gap. With the protrusion, a significantly larger range of motion and/or orientations of the finger while the finger is gripping the edge of the object may be possible, because the edge of the object is gripped more securely with the protrusion.

The protrusion may have any suitable shape. In some cases, the protrusion may have a rounded shape (e.g. a peak of the protrusion may be rounded). This may facilitate contacting the edge of the object with the protrusion, as well as facilitate pivoting of the finger relative to the object when the edge of the object is received in the gap. The protrusion may constitute a constriction in the gap (e.g. a width of the gap may become narrower in a vicinity of the protrusion).

A distal tip of the first member may extend beyond the protrusion. For example, the distal tip of the first member may be further away from an attachment region of the finger (for attaching the finger to a gripper) than the protrusion. Thus, when the object is gripped between the first member and the protrusion on the second member, the first member may contact the lower surface of the object at a first position that is further away from an extremity of the edge of the object than a second position where the protrusion contacts the upper surface of the object. Such an arrangement may serve to avoid the edge of the object falling out of the gap. In particular, the protrusion may act to block pivoting of the object about its contact point with the first member, so that the edge of the object is reliably held in the gap.

The gap may comprise a first portion and a second portion, the first portion being located between an opening of the gap and the second portion, such that the edge of the object extends through the first portion and into the second portion when the edge of the object is received in the gap. A maximum width of the second portion of the gap is greater than a minimum width of the first portion of the gap. In other words, the gap may include the first narrower portion and a second wider portion. In use, the second, wider portion of the gap may receive an extremity of the edge. The wider second portion may facilitate the pivoting motion of the finger described above for gripping the object, as it may allow an amount of relative motion between the extremity of the edge and the finger when the pivoting motion is performed. This may also facilitate using the finger with a variety of objects, as the wider second portion may accommodate objects with edges having different thicknesses.

Where the second member includes a protrusion as discussed above, the protrusion may be arranged in the first portion of the gap. Thus, the minimum width of the first portion of the gap may correspond to where the protrusion extends in the gap towards the first member. Accordingly, the second portion of the gap and the opening of the gap may be arranged on opposite sides of the gap relative to the protrusion.

An opening of the gap may flare outwards. This may facilitate inserting the edge of the object into the gap, as the flared opening may act to guide the edge into the gap. This may also enable the edge of the object to be inserted into the gap over a wider range of relative angles between the finger and the object.

The opening of the gap may refer to an end of the gap through which the edge of the object protrudes when the edge of the object is received in the gap.

The first member may be substantially straight. This may facilitate insertion of the edge of the object into the gap, as the finger may be approached towards the edge of the object in a direction aligned with the first member. In other words, this may enable the edge of the object to be inserted into the gap via a linear movement of the finger. In particular, the inventors have found that a substantially straight first member may facilitate picking up objects such as plates, as this may facilitate gripping an edge of a lip of the plate. As a result of the first member being substantially straight, an edge of the gap defined by the first member may be substantially straight.

The first member being substantially straight may mean that at least a portion of the first member has substantially straight (e.g. parallel) edges. For example, the first member may comprise a substantially straight bar or rod. The first member being substantially straight may be preferred for plates, for example, because plates typically have a flat and/or straight outer edge. Therefore, a straight first member may be easier to insert between stacked plates that a curved first member. The first member being straight may also reduce an overall width of the first member. For example, if a body of the first member is 1 mm thick but has a significant curve, an overall thickness of the first member (the minimum straight gap it can achieve at full depth) is much larger than a 1 mm thick straight first member.

In other embodiments, the first member may be curved. This may facilitate picking up objects having an edge with a curved profile, as the curved first member may provide good support for the curved edge. In particular, making the first member curved may enable a contact area between the edge of the object and the first member to be increased when the edge is received in the gap. The curvature of the first member may be arranged to match a curvature of the edge of the object, which may further facilitate insertion of the edge into the gap. As a result of the first member being curved, an edge of the gap defined by the first member may be curved.

A side surface of the finger may be configured as a gripping surface. In this manner, in addition to being used for holding the edge of an object in the gap, the finger can be used for holding an object against its gripping surface. In other words, the finger may be used to grip objects according to two modalities: 1) when receiving the edge of an object in the gap between the first and second members, and 2) using the gripping surface on the side of the finger. Thus the finger may be used for gripping and holding a wide variety of objects. For example, the finger can be used to pick up various items of dishware (e.g. plates) using the gap between first and second members as discussed above, as well as to pick up other objects such as cutlery using the gripping surface. As an example, in use a robotic gripper may include two fingers, where the two fingers are arranged such that their gripping surfaces face each other. Then, the two fingers can be moved towards each other, in order to grip an object between the gripping surfaces of the two fingers.

The side surface of the finger may be on a side of the finger which, when in use in a robotic gripper, is arranged to face towards another finger of the gripper. The side surface of the finger may also be referred to as an inner surface of the finger. The gripping surface may be any suitable surface against which an object can be held or gripped. In particular, an object may be held or gripped against the gripping surface when pressed against the gripping surface, e.g. using a second finger as mentioned above. In some cases, the gripping surface may be substantially flat. This may enable a wide variety of objects to be held against the gripping surface. In other cases, the gripping surface may have different shapes, e.g. the gripping surface may be curved. In some cases, a shape of the gripping surface may be adapted to a shape of an object to be gripped, which may facilitate holding the object against the gripping surface.

The gripping surface may be textured, e.g. with dimples, corrugations or treads, to improve a gripping quality of the gripping surface.

The second member may form an edge of the gripping surface. The edge of the gripping surface may thus be defined at least in part by the gap between the second member and the first member. Accordingly, the second member may form part of the side surface of the finger on which the gripping surface is arranged. In this manner, the second member and the gripping surface may be integrated with one another, which may result in a more compact and convenient shape of the finger.

The finger may comprise an anti-slip coating. This may facilitate gripping of objects with the finger, and reduce a risk of slippage between the finger and the gripped object. In this manner, a performance of the finger may be improved. The anti-slip coating may comprise any suitable material for increasing friction and reducing a risk of slippage. For example, the anti-slip coating may comprise a rubber material, a rubber coating (e.g. a rubber-infused paint), or similar.

The anti-slip coating may be applied to the entire finger. Alternatively, the antislip coating may be applied to regions of the finger where the finger is likely to contact gripped objects. For example, the anti-slip coating can be applied to one or more of the first member, the second member (including the protrusion mentioned above), and the gripping surface.

As mentioned above, the finger of the invention may be incorporated into a robotic gripper. Accordingly, a second aspect of the invention provides a robotic gripper comprising one or more fingers of the first aspect of the invention. Any features described above in connection with the first aspect of the invention are equally applicable to the second aspect of the invention (and vice versa).

The robotic gripper may be any suitable robotic device capable of actuating (moving) the one or more fingers in order to grip an object with the one or more fingers. The robotic gripper may include any suitable actuation mechanism for moving the one or more fingers, such as an electric motor, a hydraulic actuator, and/or a pneumatic actuator.

In one embodiment, the robotic gripper may comprise a pair of fingers of the first aspect of the invention. Providing the robotic gripper with two fingers may improve a stability with which the robotic gripper can grip the edge of an object. In particular, the two fingers may be arranged so that the edge of the object can be simultaneously received in the gap of each finger. In this manner, the edge of the object can be simultaneously gripped at two locations, thus improving a stability with which it can be held. The inventors have found that such an arrangement may be particularly beneficial for large objects such as plates. Note that embodiments comprising a pair of fingers are not limited to having two fingers, and may include additional fingers, i.e. they may comprise two or more fingers.

The robotic gripper may be configured to move the pair of fingers relative to one another, to control a spacing between the pair of fingers. This may facilitate gripping the edges of objects of different sizes, as the spacing between the two fingers can be adjusted to fit the object to be gripped. For example, this may enable plates of different diameters to be gripped. Where an object having a smaller size (e.g. diameter) is to be gripped, the robotic gripper may set the spacing to a first, smaller value, so that the edge of the object can simultaneously be received in the gap of each of the two fingers. Where a second object having a larger second size (e.g. diameter) is to be gripped, the robotic gripper may set the spacing to a second, larger value. The spacing between the fingers may be controlled either manually by a user, or automatically by a controller which is configured to control the robotic gripper.

The robotic gripper may be configured to move the pair of fingers relative to one another, to grip an object between the pair of fingers. In this manner, an object can be gripped between the two fingers so that the object can be picked up. For example, in line with the discussion above, each of the two fingers may each have a gripping surface, and the gripping surfaces of the two fingers being arranged to face one another. Thus, the object may be held between the gripping surfaces of the pair of fingers.

Accordingly, the robotic gripper including a pair of fingers can be used for gripping objects according to two different modalities: 1) by gripping the edge of an object received in the gaps of the two fingers, and 2) gripping an object between the two fingers (e.g. between the gripping surfaces of the two fingers).

The robotic gripper may be a parallel gripper. In this manner, the spacing between the pair of fingers may be accurately controlled, so that the spacing between the fingers may readily be adjusted to fit an object to be gripped. Herein, a parallel gripper may refer to a robotic gripper where the fingers are movable relative to one another along an axis. The two fingers may be parallel to one another, and may remain parallel as they are moved relative to one another.

Use of a parallel gripper may be particularly suited to picking up tableware items such as plates. In particular, adjusting the spacing between the fingers whilst maintaining the fingers parallel to one another may facilitate simultaneously inserting the edge of the plate into the gap of each finger.

Other types of robotic grippers (such as robotic hands or pinchers) may also be used, which may involve different types of relative movement between the fingers.

The robotic gripper may also be referred to as an end effector.

In use, the robotic gripper may be mounted on a robotic arm, or other robotic device, so that the robotic gripper can be moved around. This may enable, for example, the robotic gripper to pick up and set down objects at different locations.

In a third aspect, the invention provides a robotic system comprising: a robot comprising a robotic gripper according to the second aspect of the invention; a controller configured to control the robot to pick up an object by: approaching the gripper towards an edge of the object to insert the edge of the object into the gap of the one or more fingers; and pivoting the gripper to cause the edge of the object to be gripped between the first member and the second member of the one or more fingers. Features described above in connection with the first and second aspects of the invention are equally applicable to the third aspect of the invention (and vice versa). The robot may comprise any suitable robot or robotic device capable of performing required movements with the gripper to pick up and set down an object.

The robot is configured to move the robotic gripper, to enable picking up and setting down of objects with the robotic gripper. For example the robot may be configured to move the robotic gripper in one, two or three dimensions. The robot may also be configured to pivot and/or rotate the robotic gripper, e.g. so that the edge of the object can be gripped.

By way of example, the robot may comprise a robotic arm on which the robotic gripper is mounted. In some cases, the robot may comprise a cartesian (or linear) robot.

The controller is configured to control the robot (including the robotic gripper). The controller may be implemented using any suitable computing device or microcontroller capable of controlling movements of the robot. The controller may implement a control algorithm for controlling movements of the robot, e.g. to cause the robot to pick up and/or set down an object. For instance, the controller may comprise a processor and a memory storing computer instructions, wherein execution of the computer instructions by the processor causes the robot arm to perform the movements for picking up (and/or setting down) an object.

The controller may be configured to control the robot (including the robotic gripper) to execute one or more pre-programmed motions.

The controller may be configured to use computer-vision for recognising the location and/or dimensions and/or shape of an object to be picked up. The robot may comprise a camera or other imaging device for obtaining an image of the object to be picked up. Alternatively, the robot may be connected to, or in communication with, a camera or other imaging device for obtaining an image of the object to be picked up.

In order to pick up an object, the controller controls the object to approach the gripper towards the object, so that the edge of the object is inserted into the gap of the one or more fingers of the gripper. Where the gripper includes two or more fingers, the spacing between the two or more fingers may be adjusted so that the edge of the object can simultaneously be received in the gap of each of the fingers.

The approaching motion of the gripper towards the edge of the object may comprise any suitable motion for inserting the edge into the gap, and may be adapted to the specific shapes of the gap and the edge of the object. For example, the approaching motion may comprise a combination of one or more linear motions, rotational motions and/or pivotal motions of the gripper.

Once the edge of the object is inserted into the gap of the one or more fingers, the controller controls the robot to pivot the gripper relative to the object. As discussed above, the pivoting motion may be in a plane substantially normal to a surface on which the object rests. This may cause the edge of the object to be gripped between the first member and the second member. The controller may then control the robot to pick up the object, e.g. by raising the gripper upwards (i.e. away from the surface on which the object rests). The controller can then move the gripper in order to set the object down at a desired location. To set the object down, the robot may lower the object onto a surface, and pivot the gripper in an opposite direction to release the edge of the object. The gripper can then be moved away from the edge of the plate, to remove the edge of the plate from the gap of the one or more fingers.

Where the robotic gripper comprises two fingers, the controller may further be configured to control the robot to pick up an object between the two fingers. For example, the controller may control the robot to approach the gripper towards the object such that the object is located in a space between the two fingers. The controller may then control the robotic gripper to move the two fingers towards each other, to grip (clamp) the object between the to fingers. The robot can then lift the object and move the object to a desired location, where the fingers can be moved apart to release the object.

In a fourth aspect of the invention, there is provided a method of picking up an object with a robotic gripper according to the second aspect of the invention, the method comprising: approaching the gripper towards an edge of the object to insert the edge of the object into the gap of the one or more fingers; and pivoting the gripper to cause the edge of the object to be gripped between the first member and the second member of the one or more fingers. Features described above in connection with any of the previous aspects of the invention are equally applicable to the fourth aspect of the invention (and vice versa). The method of the fourth aspect of the invention may, for example, be performed with the robotic system of the third aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. la is a schematic diagram showing a plan view of a finger according to an embodiment;

Fig. lb is a schematic diagram showing a plan view of the finger of Fig. la, where various dimensions of the finger are indicated;

Figs. 2a and 2b are cross-sectional schematic diagrams depicting steps for picking up a plate using the finger of Fig. la;

Fig. 3a is a schematic diagram showing a top view of a robotic system according to an embodiment, where the robotic system is being used to pick up a plate;

Fig. 3b is a schematic diagram showing a top view of the robotic system of Fig. 3a, where the robotic system is being used to pick up a cup; and

Figs. 4-8 are schematic diagrams showing plan views of fingers according different embodiments.

DETAILED DESCRIPTION

Fig. la is a schematic diagram of a finger 100 for a robotic gripper according to an embodiment. The schematic diagram of Fig. la shows a plan view of the finger 100. The finger 100 is designed for gripping the edge of an object, so that the robotic gripper can pick up the object with the finger 100. The finger 100 is particularly suited for use in picking up objects such as plates or other similar tableware items.

The finger 100 includes a first member 102 and a second member 104 which are spaced apart such that a gap 106 is formed between the first member 102 and the second member 104. The gap 106 is configured to receive an edge of an object (such as an edge of a plate or other tableware item). In particular, the gap 106 is dimensioned so that the edge of the object can be inserted into the gap 106. When the edge of the object is inserted into the gap 106, the first member 102 may contact a lower surface of the edge of the object, e.g. to support the edge of the object. The finger 100 can then be rotated to bring the second member 104 into contact with an upper surface of the edge of the object, so that the edge of the object is gripped between the first member 102 and the second member 104. In more detail, the second member 104 includes a protrusion 108 that extends in the gap 106 towards the first member 102, the protrusion 108 being arranged to contact the upper surface of the edge of the object when the finger 100 is pivoted relative to the object. Gripping of the edge of an object with the finger 100 is described in more detail below with reference to Figs. 2a and 2b. The protrusion 108 (e.g. a peak of the protrusion 108) may be rounded. This may facilitate engagement between the protrusion 108 and the edge of the object, as well as reduce a risk of damage to the edge of the object. The rounded protrusion 108 may also facilitate pivoting the finger 100 relative to the object when the edge of the object is received in the gap 106.

The finger 100 is configured to be mounted in a robotic gripper. Thus, the finger 100 may include an attachment region 110 for attaching the finger 100 to the robotic gripper. In the example shown, the attachment region 110 includes a pair of through- holes 112 for attaching the finger 100 to the robotic gripper. However, the attachment region 110 may include any other suitable features for enabling attachment (connection) to a robotic gripper. The first and second member 102, 104 are arranged such that they extend longitudinally away from the attachment region 110, i.e. so that an opening of the gap 106 faces away from the attachment region 110.

A side surface 114 of the finger 100 is configured as a gripping surface. The side surface 114 is on a side of the second member 104, and provides a large planar surface which can be used for gripping an object, as discussed in more detail below with reference to Fig. 3b. Thus, an edge of the second member 104 which extends along the gap 106 corresponds to an edge of the side surface 114.

Example dimensions of the finger 100 will now be provided, with reference to Fig. lb. Fig. lb shows the same view as Fig. la of the finger 100, and additionally indicates various dimensions of the finger 100. As shown, the first member 102 is a substantially straight elongate element having a length 116 and a thickness 118. The length 116 of the first member 102 may be between about 5 mm and 20 mm, whilst the thickness 118 of the first member 102 may be between about 1 mm and 5 mm. Such a thickness of the first member 102 may facilitate inserting the first member under the edge of an object to be picked up. In particular, this may enable the first member 102 to fit between the edges of stacked objects (e.g. stacked plates), so that an object can be picked up from a stack. A distal tip 120 of the first member 102 may be rounded. This may serve to avoid damaging an object when picking up the object with the finger 100. As can be seen, the distal tip 120 of the first member 102 extends beyond the protrusion 108, e.g. the distal tip 120 is further from the attachment region 100 than the protrusion 108. For example, as illustrated in Fig. lb, the distal tip 120 of the first member 102 may be further from the attachment region 100 than the protrusion 108 by a distance 117 parallel with the length 116 of the first member.

However, the distal tip 120 of the first member 102 may be set back relative to a leading edge 121 of the second member 104. In particular, as shown, there may be an offset 123 between the distal tip 120 of the first member 102 and the leading edge 121 of the second member 104. The offset 123 may, for example, be between about 0.5 mm and 10 mm.

The thickness 118 of the first member 102 may be smaller than a minimum width 122 of the gap 106. In line with the discussion above, this may facilitate inserting the first member 102 under the edge of the object to be picked up, and facilitate picking up the object from a stack of objects. The minimum width 122 of the gap 106 corresponds to a location of the protrusion 108, which acts as a constriction in the gap 106. The minimum width 122 of the gap 106 may be dimensioned to fit the edge of an object to pick up. By way of example, the minimum width 122 of the gap may be between about 1 mm and 5 mm.

The opening of the gap 106 (facing away from the attachment region 110) flares outwards. This may facilitate guiding the edge of an object into the gap 106. In particular, as shown in Fig. lb, the gap 106 is provided with an opening angle 124 that flares outwards. The opening angle 124 may be defined between an edge the first member 102 and an edge of the second member 104 located at the opening of the gap 106. In particular, the edges of the first and second members 102, 104 are angled relative to one another at the opening of the gap 106 so that a width of the gap increases towards the opening of the gap 106. By way of example, the opening angle 124 may be between about 10 degrees and 45 degrees. In the example of Fig. lb, the opening angle is about 12 degrees. A length 125 of the edge of the second member 104 located at the opening (i.e. between the leading edge 121 and the protrusion 108) may, for example, be between 5 mm and 20 mm.

Starting at the opening of the gap 106, a first portion of the gap 106 progressively narrows from the opening towards a peak of the protrusion 108. The gap 106 reaches its minimum width 122 around the peak of the protrusion 108, following which a width of the gap 106 subsequently increases. In particular, a second portion of the gap 106, located on an opposite side of the peak of the protrusion 108 relative to the opening of the gap 106, has a maximum width 126 which is greater than the minimum width 122 of the gap 106. In other words, the gap 106 widens again following its narrowing caused by the protrusion 108. The maximum width 126 of the second portion of the gap 106 may, for example, be between about 5 mm and 15 mm. The wider second portion of the gap 106 may in use receive an extremity of an edge of the object to be picked up. The increased width of the second section of the gap 106 may enable the finger 100 to be pivoted relative to the object, as discussed further below. In the example shown, an edge of the second portion of the gap 106 has a rounded shape.

A width 128 of the side surface 114 may be adapted to enable effective gripping of objects. By way of example, the width 128 of the side surface 114 may be between about 10 mm and 40 mm. This may allow for a suitably large surface area on the side surface 114 to provide a large gripping surface. Other dimensions of the finger 100 may be adapted to the robotic gripper with which the finger 100 is to be used, as well as dimensions of the objects that are to be picked up with the finger 100. For instance, a total length 130 of the finger 100, and a length 132 of the attachment region may be set in accordance with design needs. By way of example, the total length 130 of the finger 100 may be between about 30 mm and 80 mm, and the length 132 of the attachment region 110 may be between about 5 mm and 30 mm.

The finger 100 may be made of any suitable material, such as a metal (e.g. aluminium, steel), plastic or composite material. The finger 100 may be integrally formed as a single piece, or it may be formed as multiple pieces which are subsequently assembled together. In some cases, the finger 100 may be provided with an anti-slip coating, to improve its ability to grip objects. The anti-slip coating may be applied to the entire finger 100. Alternatively, the anti-slip coating may be applied to regions of the finger 100 where the finger is likely to contact gripped objects. For example, the antislip coating can be applied to one or more of the first member 102, the second member 104(including the protrusion 108), and the side surface 114.

An example use of the finger 100 will now be described with reference to Figs. 2a and 2b. Figs. 2a and 2b are cross-sectional views illustrating steps for picking up a plate 200 from a stack of plates with the finger 100. The plate 200 is a tableware item which is used for holding food, having a typical plate-shape. In particular, the plate 200 includes a base (or well) 202 which may be substantially flat, and a lip 204 surrounding the base 202. The lip 204 is slanted upwards relative to the base 202, in order to prevent food from spilling out of the base 202. The plate 200 is located in a stack of identical plates. In this configuration, there is a gap between the lip 204 of the plate 200 and the lip of the underlying plate. For illustration purposes, only part of the plate 200 and an underlying plate are depicted in Figs. 2a and 2b.

The finger 100 is used to grip an edge of the lip 204 of the plate 200, so that the plate 200 can be lifted upwards. In particular, as shown in Fig. 2a, the finger 100 is approached towards the lip 204 of the plate 200 to insert the edge of the lip 204 into the gap 106 of the finger 100. To do this, the finger 100 may be angled to allow the lip 204 of the plate 200 to enter into the gap 106. The lip 204 is inserted into the gap 106 until a tip of the lip 204 passes beyond the protrusion 108. In this position, the first member 102 fits into the gap between the lip 204 of the plate 200 and the lip of the underlying plate. The first member 102 may contact a lower surface of the lip 204 of the plate 200. Then, as indicated by arrow 206 in Fig. 2b, the finger 100 may be pivoted relative to the plate 200, in order to bring the protrusion 108 into contact with an upper surface of the lip 204. In more detail, the finger 100 is pivoted away from the plate 200 (i.e. in an anticlockwise direction in Fig. 2b), the pivoting being in a plane that is substantially normal to a surface on which the plate 200 rests.

Following the pivoting motion 206, the lip 204 of the plate 200 is contacted on its lower surface by the distal tip 120 of the first member 102 and on its upper surface by the peak of the protrusion 108. In this manner, the lip 204 of the plate 200 may be gripped (held) between the first member 102 and the second member 104 of the finger 100. In this position (i.e. the position of Fig. 2b), the finger 100 can be moved upwards as indicated by arrow 208, in order to lift the plate 200 off of the stack of plates. As the centre of mass of the plate 200 is spaced outwards from the finger 100, the gravitational force acting on the plate 200 will try to make the plate 200 pivot about its contact point with the first member 102. However, such pivoting motion of the plate 200 is blocked due to contact with the protrusion 108 on the second member 104, such that the lip 204 of the plate 200 is effectively wedged between the first and second members 102, 104 once it is lifted up. The finger 100 may be further pivoted in the direction indicated by arrow 206, in order to reduce a risk of the lip 204 slipping out of the gap 106 in the finger 100.

To subsequently set the plate 200 down, an inverse sequence of motions may be performed with the finger 100. Specifically, the finger 100 may first be moved downwards to set the base 202 of the plate 200 onto a surface. The finger 100 can then be pivoted in a direction opposite to that shown by arrow 206, to release the edge of the lip 204. Subsequently, the finger 100 can be moved away from the plate 200, to remove the edge of the lip 204 from the gap 106 in the finger 100.

Although Figs. 2a and 2b depict the finger 100 being used for picking up a plate 200, the finger may also be used for picking up other types of object having a similar shape, or with a lip or edge that can be received in the gap 106. The finger 100 may be attached to a robotic gripper and/or a robot arm (not shown), in order to perform the required movements for picking up and setting down the plate 200.

Figs. 3a and 3b show schematic diagrams of a robot system 300 according to an embodiment. Figs. 3a and 3b show an example top view of the robot system 300. The robot system 300 includes a robot in the form of a robotic arm 302. In the example shown the robotic arm 302 is an articulated robotic arm comprising multiple articulated parts, although other types of robotic arm may be used. The robotic arm 302 includes a robotic gripper 304 mounted at an end of the robotic arm 302. The robotic gripper 304 includes a pair of fingers 306 for gripping objects. For example, each finger 306 may correspond to the finger 100 described above. The two fingers 306 are movable relative to each other, such that a spacing between the two fingers 306 can be adjusted. In one example, the robotic gripper 304 may be a parallel gripper, although other types of gripper may also be used. The robotic arm 302 is configured to move the robotic gripper 304 in three dimensions, as well as to enable pivoting of the robotic gripper 304. For example, the robotic gripper 304 may be pivotably mounted at the end of the robotic arm 302.

The robotic system 300 further includes a controller 308 which is configured to control motions of the robotic arm 302 and the robotic gripper 304. The controller 308 may be communicatively coupled to the robotic arm 304 (via a wireless or wired connection), so that it can provide control signal for controlling motions of the robotic arm 302 and the robotic gripper 304. In some cases, the controller 308 may be integrated into a part of the robotic arm 302.

In the example shown in Fig. 3a, the robotic system 300 is used to pick up a plate 310. The plate 310 may be like the plate 200 described above, i.e. including a base and surrounding lip. In Fig. 3a, the lip of the plate 310 is received in the gap (e.g. gap 106) of each of the fingers 306. A spacing between the two fingers 306 may be adjusted to improve a stability with which the plate 310 is held. For example, by holding the plate 310 at two points on its lip which are spaced apart may improve a stability (balance) with which the plate 310 is held. The robotic gripper 304 may adjust the spacing between the fingers 306 so that it is adapted to a size of the plate 310. For instance, the spacing between the fingers 306 may be increased to hold larger plates, whilst it may be decreased to hold smaller plates.

The plate 310 may be picked up using a process analogous to that described above in relation to Figs. 2a and 2b. In particular, the robotic arm 302 may initially approach the gripper 304 towards the plate 310 so that the lip of the plate 310 is inserted into the gaps of the fingers 306 (i.e. so the lip of the plate 310 is simultaneously received in the gap of each finger 306). The robotic arm 302 can then pivot the gripper 304 relative to the plate 310, so that the lip of the plate 310 is gripped in the gaps of the two fingers 306. The robotic arm 302 can then lift up the gripper 304 to lift the plate 310 off of the surface and move the plate 310 to set in down at a desired location.

In the example shown in Fig. 3b, the robotic system 300 is used to pick up a cup 312. Here, instead of using the gaps in the fingers 306, the cup is gripped between side surfaces of the fingers 306. In particular, each finger 306 includes a side surface (e.g. side surface 114) which is configured as a gripping surface, the side surfaces of the two fingers 306 being arranged to face each other. In this manner, the fingers 306 can be moved together in order to grip an object between their side surfaces. Thus, objects which may not be suitable for picking up using the gaps in the fingers 306 can still be picked up by gripping (clamping) the objects between the fingers 306.

For instance, to pick up the cup 312, the robotic arm 302 may initially approach the gripper 304 towards the cup 312 with the fingers 306 spaced apart (e.g. spaced further apart than an outer diameter of the cup 312). Then, with the fingers 306 arranged on either side of the cup 312, the gripper 304 may move the fingers 306 towards one another so that the cup 312 is held between the side surfaces of the two fingers 306. The robotic arm 302 can then move the cup 312 to a desired location, and release the cup 312 by moving the fingers 306 apart from each other. A variety of other objects other than the cup 312 can be gripped in a similar manner, including other tableware items such as items of cutlery.

The controller 308 may be implemented using any suitable computing device capable of controlling motions of the robotic arm 302 (including the gripper 304). For example, the controller 308 may implement an algorithm defining steps for picking up a variety of different objects with the robotic arm 302. The controller 308 may be configured to automatically control movements of the robotic arm 302 for picking up an object. Additionally or alternatively, the controller 308 may include a user interface, to enable a user to input commands for controlling the robotic arm 302.

Figs. 4-7 show schematic diagrams of fingers 400, 500, 600 and 700, respectively. These fingers are embodiments which represent variations of the finger 100 described above, where various dimensions and/or angles have been changed. Accordingly, the same reference numerals as in Fig. 1 are used in Figs. 4-7 for corresponding features. Any of the features described above in relation to the finger 100 may be shared with any of the fingers 400-700 (and vice versa).

Compared to the finger 100, finger 400 has an extended attachment region 110. Thus, with the finger 400, the gap 106 may be located further away from where the finger 400 is attached to the gripper. Extending the attachment region 110 in this manner may facilitate approaching the finger 400 towards the edge of an object to be gripped, as it may avoid the gripper interfering with the object and/or the surface on which the object is located.

Compared to the finger 100, the opening angle 124 of the finger 500 is larger. The minimum width 122 of the gap 106 may also be larger. This may enable the finger 500 to be used with a larger variety of objects, as increasing the size of the opening may enable the gap 106 to receive a wider range of edge sizes.

In contrast to the finger 100, the first member 102 of the finger 600 slants away from the second member 104. This may enable the finger 600 to be approached towards an object at a shallower angle to insert the edge of the object into the gap 106 (e.g. compared to the approach angle used with the finger 100 in Fig. 2a), which may facilitate use of the finger with certain gripper and/or robotic arm designs. The finger 600 also has a larger opening angle 124 and a larger minimum width 122 of the gap 106.

The finger 700 has a shallower gap 106 compared to the finger 100. Accordingly, the finger 700 may be configured to pick up smaller objects, or objects having a smaller edge. The finger 700 also has a larger opening angle 124, which may facilitate guiding the edge into the gap 106.

Fig. 8 is a schematic diagram of a finger 800 according to an embodiment. Features of the finger 800 which correspond to features of the finger 100 described above are indicated in Fig. 8 with the same reference numerals as in Fig. 1. In contrast to the finger 100, the first member 102 of the finger 800 is curved. Accordingly, the gap 106 of the finger 800 also has a curved shape. This may facilitate picking up an object having a curved edge. For example, a curvature of the gap 106 may be arranged to match a curvature of an object to be picked up. This may enable a contact area between the first member 102 and the edge of the object to be increased, thus improving a stability with which the object can be supported.

The example fingers of Figs. 1 and 4-8 are intended to provide examples of design variations that may be contemplated. Any suitable combination of features of these fingers may be used and is contemplated herein. The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example +/- 10%.