WO2025210360A1

WO2025210360A1 - Haptic interface apparatus

Info

Publication number: WO2025210360A1
Application number: PCT/GB2025/050715
Authority: WO
Inventors: Joshua Brown; Fernando BELLO
Original assignee: Imperial College Innovations Ltd
Current assignee: Ip2ipo Innovations Ltd
Priority date: 2024-04-03
Filing date: 2025-04-03
Publication date: 2025-10-09
Anticipated expiration: 2026-10-03
Also published as: GB202404756D0

Abstract

An aspect of the disclosure provides a haptic interface apparatus (10) for the provision of haptic feedback via a touch surface (11), the haptic interface comprising : an actuating member (12); a container (14) comprising a flexible wall (16); and a j ammable material (18) held, by the flexible wall, in an internal volume of the container; wherein the flexible wall (16) and the actuating member (12) are configured for relative movement thereby to modify the internal volume to control jamming of the jammable material (18), wherein haptic feedback at the touch surface (11) is based on control of the flexible wall (16) due to said jamming.

Description

Haptic Interface Apparatus

Field of Invention

The present invention relates to methods and apparatus, and more particularly to apparatus and methods for providing haptic signals in a haptic interface.

Background

Haptic interfaces are most often employed in virtual reality systems, where they serve to provide users with tactile feedback - either as straightforward stimulation, by way of output, or in response to some user action. They may be manipulable - e.g. , by action of a user's body part such as their hand, foot, or limb.

So called human user input devices, HUID, including computer keyboards and so forth may provide haptic interfaces. Other haptic interfaces include wearable devices such as gloves, socks, headgear, and limb coverings. Such devices may be provided by or incorporate exoskeletons. Wearable devices can be used to provide haptic signals to the wearer which may simulate interaction with an environment. For example, they may be used and controlled based on a virtual reality environment which is displayed to the wearer.

Haptic interfaces may also be used to simulate objects, with which a human user is to interact. Examples include surgical dummies for the purposes of medical training, and floor or wall surfaces with which a user is to interact as they move through a virtual reality environment .

Physical hardness, or the resistance to deformation under load, is an important haptic sensation. In medicine, hardness may allow a clinician to distinguish between types of organic tissue - for example by palpating a body of a patient, or in performing manual internal examination.

In a virtual reality environment, there may be a desire for the user to feel the difference between walking on a simulated soft grass surface as compared to walking on concrete. There may also be a wish to simulate the difference between an uneven surface, such as is experienced when crossing rough ground.

Traditionally, force feedback devices have been used to effectively mimic the sensations experienced when interacting with a soft surface. Recent advances in soft robotics have given rise to new ways of rendering hardness change in haptic interfaces with devices that can become physically harder or softer. Various engineering approaches to building, actuating and controlling such devices have been proposed. However, the vast majority of these have been based on pneumatic actuators.

The use of pneumatic actuators in this context has become widely accepted.

Another key technology is jamming, such as particle jamming. Jamming is the physical process by which the viscosity of some mesoscopic materials, such as granular materials, glasses, foams, polymers, emulsions, and other complex fluids, increases with increasing particle density. When a jammable material "jams" it may make a transition from a soft, perhaps flowable, state into a hard state in which it behaves as a solid.

Typically, this "jamming transition" happens when the density, or the packing fraction of the particles, is increased sufficiently to prevent them from flowing. As a result, when jammed, the aggregate material behaves as a solid. Jammable materials have been used in haptic interfaces - where the jamming transition is controlled to allow a part of the interface to transition from a flowable state to a jammed state.

The most popular way to cause this transition is by providing the jammable material in a sealed elastic container, rather like a balloon, and then use air pressure to control the jamming and un jamming of the material.

Summary

Embodiments of the present disclosure provide haptic interface apparatus which aims to provide improved response times and enhanced characteristics as compared to pneumatically actuated interfaces. Embodiments of the disclosure provide non- pneumatically actuated haptic interfaces.

Embodiments of the present disclosure provide at least two different mechanical approaches to particle jamming.

In an aspect there is provides a haptic interface apparatus for the provision of haptic feedback via a touch surface, the haptic interface comprising: an actuating member; a container comprising a flexible wall ; and a jammable material held, by the flexible wall, in an internal volume of the container; wherein the flexible wall and the actuating member are configured for relative movement thereby to modify the internal volume to control jamming of the jammable material, wherein haptic feedback at the touch surface is based on control of the flexible wall due to said jamming. Such arrangements may be arranged to provide a touch pad, or element of a touch pad . For example , the touch surface may provide a portion of such a touch pad . Such arrangements may also be used to provide a shaft configuration, as will be explained below .

The relative movement may comprise the actuating member pressing the j ammable material together . Said relative movement may comprise the actuating member moving to selectively reduce or increase the internal volume .

The actuating member and/or the flexible wall may be configured so that the relative movement comprises a relative linear di splacement .

The flexible wall may be fixed in position and the actuating member may move while the flexible wall remains stationary .

The apparatus may compri se a driver connected to the actuating member for forcing the actuating member to perform said relative movement , for example wherein the driver comprises a pusher such as an eccentric cam or a shaft . The driver may provide a linkage to an electromechanical actuator ( e . g . a rotary actuator such as a motor or a linear actuator such as a solenoid) .

The actuating member may be fixed in position and the flexible wall may be configured to move to provide said relative movement .

The relative movement may compri se selective retraction of the flexible wall .

A driver may be connected to the flexible wall and configured to cause said relative movement by selective application of tensile force to the flexible wall . The actuating member may be arranged to provide an actuatable wall of the container and the relative movement advances the actuatable wall into a volume surrounded by the flexible wall .

For example , the relative movement may compri se a di splacement of the actuating member along the container . For example the flexible wall may form a tube and the di splacement may be along the axi s of the tube . The tube may be of constant cros s section, and may be round . It may also be elongate . These pos sibilities offer some ways to provide the shaft configuration mentioned above .

The flexible wall may be held by the actuating member , such that the actuating member can apply force to the flexible wall to reduce the internal volume . For example it may be gripped by or fixed to the actuating member .

Reducing the internal volume may compri se constricting the internal volume using the internal wall .

Reducing the internal volume may comprise twi sting at least a part of the container, such as by twi sting the flexible wall , for example to twi st part of the flexible wall around the j ammable material . This may of fer a further way to provide the shaft configuration mentioned above .

The apparatus compri ses a holder , such as a frame , and the flexible wall may be fixed to the holder .

The actuating member may be configured to wind in at least part of the flexible wall to constrict the internal volume .

The actuating member may be connected to a driver configured to cause the actuating member to rotate to apply said force to the flexible wall , for example by winding it in or by twisting it perform said winding. The driver may comprise a rotatable element, such as a shaft, for connection to a rotary actuator such as a motor .

The flexible wall may comprise substantially inextensible portions, for example the flexible wall may be substantially inextensible.

The flexible wall may comprise substantially inelastic portions, for example the flexible wall may be substantially inelastic, for example at least a portion of the flexible wall may consist essentially of an inelastic material. The material does not have to be absolutely inelastic of course - some elasticity may be inherent in many materials, but typically the best response times are achieved where the material of the flexible wall does not stretch substantially under the tensile loads applied by jamming the jammable material.

An aspect of the disclosure provides a haptic interface apparatus for the provision of haptic feedback via a touch surface, the haptic interface comprising: a container comprising a flexible wall ; and a jammable material held, by the flexible wall , in an internal volume of the container; a magnetic field provider , configured to provide controllable magnetic field in the internal volume; wherein the jammable material comprises magnetisable elements thereby to enable the magnetic field provider to control jamming of the jammable material by varying the magnetic field in the internal volume, wherein haptic feedback at the touch surface is based on control of the flexible wall due to said jamming.

The magnetic field provider may comprise an electromagnet. The magnetic field provider may comprise a permanent magnet. It may also comprise a mover, arranged to move the permanent magnet so as to control the magnetic field in the internal volume as mentioned above.

The magnetisable elements may comprise ferromagnetic and/or ferrimagnetic material.

The flexible wall may be resilient.

In these embodiments, the flexible wall may comprise an elastic material. For example, the flexible wall may be resiliently deformed to accommodate the jammable material in the internal volume .

In an aspect there is provided a haptic interface apparatus for the provision of haptic feedback via a touch surface , the haptic interface comprising: a container comprising a flexible wall ; and a jammable material held, by the flexible wall, in an internal volume of the container; wherein a controllably deformable element is coupled to the flexible wall at locations selected so that deforming the deformable element causes the shape and/or size of the internal volume to change to control jamming of the jammable material, wherein haptic feedback at the touch surface is based on control of the flexible wall due to said jamming.

The controllably deformable element may comprise an electromechanical actuator. The controllably deformable element may comprise a shape memory alloy (SMA) .

The controllably deformable element may be connected to the flexible wall at a plurality of locations, for example the controllably deformable element may be elongate and fixed to the flexible wall at positions separated along the elongate length of the controllably deformable element. The controllably deformable element may be provided in the flexible wall, for example it may be incorporated into the wall.

The jammable material may comprise any appropriate jammable material - examples include particles, fibres, and laminar elements. For example, the jammable material may consist of particles or fibres or laminar elements. Mixtures of such elements may comprise at least one of particles, fibres, and laminar elements .

The jammable material may be configured such that jamming the jammable material causes a change in thermal conductivity of the jammable material.

For example, the jammable material may comprise thermally conductive elements configured such that jamming them together increases the apparent thermal conductivity of the jammable material .

The jammable material may also comprise compressible elements, for example resilient foam elements.

The interface apparatus described herein may comprise additional transducers such as heaters, coolers, movers (such as mechanical actuators able to move the touch surface) - examples of such movement include vibration. These transducers may be arranged to provide effects which can be mediated through the jammable material to the touch surface. The coupling of these effects to the touch surface may be modulated by the hardness and/or packing fraction of the jammable material. Accordingly, haptic feedback at the touch surface may comprise at least one of:

(i) control of apparent stiffness of the flexible wall;

(ii) control of temperature of the flexible wall;

(iii) control of shape of the flexible wall; and

(iv) vibration of the flexible wall.

In an aspect there is provided a haptic interface system comprising a plurality of haptic feedback elements, each haptic feedback element comprising a haptic interface apparatus according to any preceding claim wherein the touch surface of each haptic interface apparatus is configured to provide a part of a haptic feedback of the haptic interface system.

The haptic feedback elements may be spatially arranged to provide different component parts of a multicomponent feedback, for example the haptic feedback elements may be arranged in an array.

The flexible wall may comprise substantially inextensible portions arranged to cause said jamming, for example the flexible wall may be substantially inextensible.

The flexible wall may comprise substantially inelastic portions, for example wherein the flexible wall is substantially inelastic, for example wherein at least a portion of the flexible wall consists essentially of an inelastic material.

Some embodiments provide direct compression of the jammable material by the application of mechanical force by an actuating member. Some embodiments provide constrictive actuation, in which the container which holds the jammable material is caused mechanically to constrict. The container may be soft. The container may be substantially inelastic, for example the flexible wall may be soft and inelastic. The jammable material may comprise a particulate material which may behave substantially as a fluid.

Constricting the internal volume of the container may exert a force on the jammable material, such that it becomes compressed against its soft but inelastic container. The more force that is exerted, the more compressed the fluid becomes, increasing stiffness. This may be referred to as "jamming". In some embodiments, the jammable material may exhibit a transition between an unjammed, flowable, state and a jammed state in which the material behaves as a solid.

Embodiments provide a touchpad. Some embodiments provide a shaft configuration .

The touchpad configuration can be provided by one or more touch surface elements, which may be planar. Such element (s) may provide a "tactile display" configured controllably to change their hardness .

A shaft configuration may be provided by a touch surface of a tube or similar pouch and may be configured to approximate the form and behaviour of a joystick or other hand grip element and may be particularly useful for (for example in a force feedback handle, a VR controller, a steering wheel of a simulator or a similar human used interface) . The shaft configuration may also be provided in one or more parts of a wearable article, such as a glove, an exoskeleton or limb covering to provide controllable resistance to movement of the wearer.

An embodiment of the disclosure provides a virtual reality system, comprising a user interface configured to present a user with a simulated environment and comprising at least one user interaction device arranged to allow the user to interact with the simulated environment, wherein the user interaction device comprises at least one haptic interface apparatus as described and claimed herein.

The haptic interface apparatus may be configured to simulate soft objects in the simulated environment and/or to provide tactile effects such as control of the interaction device and/or control of texture, or stiffness, vibration, or any other tactile characteristic of the surface.

Other embodiments are envisaged.

Any feature of any one of the examples disclosed herein may be combined with any selected features of any of the other examples described herein.

For example, features of methods may be implemented in suitably configured hardware, and the configuration of the specific hardware described herein may be employed in methods implemented using other hardware .

Brief Description of Drawings

Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 shows a haptic interface apparatus, which operates by movement of a movable actuating member, the apparatus is shown in both a jammed state and in an un ammed state;

Figure 2 shows a further example of a haptic interface apparatus, which operates by movement of a movable actuating member, the apparatus is shown in both a jammed state and in an unjammed state;

Figure 3 shows a haptic interface apparatus, which operates by constriction of the container which holds the jammable material, the apparatus is shown in both a jammed state and in an un jammed state;

Figure 4A shows a haptic interface apparatus, which operates by control of magnetic field in a body of jammable material comprising magnetizable elements;

Figure 4B shows a haptic interface apparatus, which operates by deformation of a deformable actuating element, connected to a flexible wall of a container holding a jammable material;

Figure 5 shows a further haptic interface apparatus, which operates by constriction of the container which holds the jammable material, the apparatus is shown in both a jammed state and in an un jammed state; and

Figure 6 shows a further example of a haptic interface apparatus, which operates by movement of a movable actuating member, the apparatus is shown in both a jammed state and in an un jammed state.

In the drawings like reference numerals are used to indicate like elements .

Specific Description

Figure 1 shows a haptic interface apparatus 10 for the provision of haptic feedback. The apparatus shown in Figure 1 comprises a container 14, 16 which, in this example is, provided by a flexible wall 16 held in position by a spacer frame 14. The container 14, 16 has an internal volume in which is disposed a jammable material 18, such as particles.

The spacer frame 14 supports the flexible wall 16 in a selected shape to allow an actuating member 12 to move into and out from the internal volume of the container 14, 16.

The jammable material 18 is disposed between the flexible wall 14 and the actuating member 12 in the internal volume of the container. Thus, it can be seen that the jammable material 18 is positioned to allow the actuating member 12 to press it against the flexible wall 16.

The actuating member 12 is movable, for example it may be able to slide in the frame 14 so as to move into and out from the internal volume. The actuating member 12 may comprise a pusher surface which is sufficiently rigid to serve to press the jammable material 18 together. Thus, the jammable material 18 can be jammed and unjammed by the application and removal of force on the actuating member 12 - e.g. to cause it to advance toward the flexible wall 16 and to retreat from it. It can also be seen in Figure 1 that the actuating member 12 is operable to be driven in the manner of a piston to provide this pressing function.

A driver 20, such as a mechanical linkage, may be may also be provided. In the example illustrated in Figure 1, the driver comprises a rotatable cam 20 arranged to be rotated by a shaft. The cam 20 may be eccentric and operable to:

(a) push the actuating member 12 towards the flexible wall 16 (and into the internal volume of the container) so as to press on the jammable material 18; and (b) allow or cause the actuating member 12 to retreat from the flexible wall 16 (and out from the internal volume of the container) so as to reduce the pressing of the jammable material 18.

Operation of the apparatus 10 shown in Figure 1 will now be described .

In operation, with the actuating member 12 in a first position withdrawn from the internal volume of the container, the touch surface 11 may initially be in a relatively softer state. Accordingly, the internal volume of the container 14, 16 is large enough to accommodate the jammable material 18 in an unjammed state. This is shown in the upper part of Figure 1.

To cause the touch surface 11 to harden or stiffen the actuating member 12, can be moved by the driver towards a second position, spaced from the first position further into the internal volume of the container 14, 16. The actuating member 12 is thus driven against the jammable material 18 to urge the jammable material together. As the actuating member 12 is pressed into the internal volume the internal volume is reduced. This causes the jammable material 18 to jam together, and transition from a flowable (e.g. , quasiliquid) state into a solid. It may also be pressed against the flexible wall 14. Accordingly, the apparent stiffness of the touch surface 11 carried by the flexible wall 16 increases because it now lies against a solid body provided by the jammed material 18. By contrast, when the material 18 is unjammed the flexible wall 16 lies against a flowable material and so is softer.

It will be appreciated that a touch surface 11 of a haptic interface may be provided by the flexible wall 16 itself. Such a touch surface may also be carried on or otherwise coupled to the flexible wall, so the flexible wall can control its apparent stiffness. When the actuating member 12 is driven from the first position, in which the jammable material is unjammed, to the second position in which the jammable material 18 is jammed the apparent hardness/ stiffness of the haptic interface at that touch surface will respond accordingly. For example it may transition from a soft state when the actuating number 12 is in the first position to a harder or stiffer state when the actuating member 12 is in the second position. This may permit a variety of effects to be provided at the touch surface.

The driver 20, such as the cam, and any mechanical arrangement for applying force to the driver may be made and sold separately from the apparatus 10.

The arrangement illustrated in Figure 1 offers one way in which an actuating member might provide an actuatable wall of a container able to advance into a volume which is bounded on at least one side by a flexible wall. Other implementations of such systems are possible and will be described below.

The apparatus described and claimed herein may provide a constituent part of a larger system and may be sold as a component in its own right (e.g. , as a part to be integrated into such an apparatus) . For example, a plurality of such apparatus may be arranged in an array, so that each apparatus provides an element of the array. For example, each apparatus may be arranged to control stiffness of a corresponding element of a touch surface - such elements may provide "pixels" of a haptic display. Thus an entire surface might be controlled, with individual elements of that surface being controlled independently.

Other implementations of the present disclosure are contemplated. For example, in the arrangement shown in Figure 1, a spacer frame 14 is used to facilitate movement of the actuating member into and out from the internal volume of the container, but this is optional.

Figure 2 shows a haptic interface apparatus 10' in which no spacer frame is present. In this example the flexible wall 16 forms at least two sides of the container, and a further side of the container is provided by the actuating member 12. The flexible wall 16 is positioned so that the actuating member 12 can slide into and out from an internal volume formed by the flexible wall 16. In the example illustrated in Figure 2, this is provided by the flexible wall 16 being arranged in the shape of a tube, which may be elongate. The actuating member 12 may be shaped to provide an end wall of that tube, which can slide into the internal volume of the tube, along its axis. A jammable material 18 is provided in the internal volume of the container.

The tube illustrated in Figure 2 is round so the actuating member 12 comprises a disc, arranged to provide a movable end wall of the tube. The internal volume of the container is bounded on one side by the actuating member and on its other sides by the flexible wall. The disc is affixed to a driver 20' in the form of a rod, aligned with the axis of the tube, which is operable to force the actuating member 12 to advance into and retreat out from the internal volume.

The flexible wall 16 may be fixed in position (e.g. , tethered) with respect to the driver to allow the actuating member to apply force to the jammable material 18 in the internal volume of the container.

The upper drawing in Figure 2 shows the actuating member 12 in a first position, withdrawn from the internal volume sufficiently to accommodate the jammable material 18 in an un ammed state. Figure 2 also shows the actuating member 12 in a second position, where it has been advanced axially into the tube to reduce the internal volume sufficiently to cause the jammable material 18 to jam against the flexible wall 16.

The flexible wall 16 of the apparatus shown in Figure 2 may provide all of the container, but as illustrated the container may also comprise some rigid or supporting parts, such as one or more end caps 13 which are illustrated in Figure 2. Such end caps 13 may be provided at one or both ends of the container 16. For example, they may be disposed at the axial ends of the tube. However, this is optional and no such structures are necessary - for example the flexible wall may be sufficiently rigid so as to hold its shape without additional support but, as noted above, the flexible wall 16 may be tethered or otherwise fixed in place. The

By these or other means, the interface apparatus is able to provide relative movement between the actuating member 12 and the flexible wall 16 so as to cause the size of the internal volume to be controlled by that relative movement to cause the jamming and unjamming of the jammable material 18. In these and other examples, the actuating member 12 may provide an actuatable wall of the container 16.

Where the flexible wall 16 is arranged to provide a tube, and the actuating member 12 moves along the axis of that tube, the actuating member 12 can be mounted on a shaft 19, such as a pusher rod. This rod may pass through an aperture in one of the end caps 13. The apparatus may be held in place by fixing this end cap 13. This can allow the actuating member to be pushed and pulled linearly (e.g. along its axis) to move the actuating member 12 into and out from the internal volume. However other means of providing such linear motion may be used, for example the actuating member 12 may be fixed to a line which may pass through the jammable material so that the actuating member can be pulled into the tube to compress the internal volume and tension in the line can be released to allow the jammable material 18 to unjam.

However it is achieved, whether as illustrated in Figure 2 or otherwise, the actuating member 12 may be configured to operate in the manner of a piston to cause the internal volume to decrease and increase and the jammable material 18 to un am and jam accordingly.

The embodiments described above may operate by linear reciprocating movement of the actuating member 12 relative to the flexible wall 16. However, other types of relative movement may also provide control of the internal volume to control jamming of the jammable material 18. One possibility is a rotational movement such as a twist of the flexible wall. One example is illustrated in Figure 3.

Figure 3 shows an arrangement in which the flexible wall 16 surrounds the jammable material 18, for example, the flexible wall may be in the form of a pouch. Part of this flexible wall 16 may be fixed in position, such as by a frame 14. Another part of the flexible wall 16, such as at the other end from the part which is fixed in place, may be fixed to an actuating member 12. The actuating member 12 is able to rotate to twist the flexible wall 16 between the fixed part and the actuating member 12. A driver 22, such as a rotatable shaft may be coupled to the actuating member 12 for driving the actuating member 12 to rotate. A motor (not shown) may be connected to the actuating member 12 by the shaft 22. As noted below, gearing may be used to increase torque supplied by such a motor.

In operation, when the actuating member 12 is driven to rotate the flexible wall 16 becomes at least partially twisted around the jammable material 18, thereby constricting the internal volume of the container. As the internal volume becomes progressively constricted, the jammable material 18 can be forced into the jammed state. In the example illustrated in Figure 3, the flexible wall is shown as being twisted predominantly at one end of the container, thereby to laterally compress the jammable material towards the other end of the container. This drawing however is merely schematic, and other arrangements are contemplated. For example the container as a whole may twist around the jammable material 18 to compress it radially without compressing it longitudinally. For example, in a tube-shaped container the axial extent of the jammable material 18 may remain the same whilst it is compressed by radial constriction due to twisting.

The example shown in Figure 3 includes a frame 14, to which the flexible wall 16 is fixed. However, even in examples where the actuating member is rotatable to apply force, such a holder or frame is also optional. The flexible may be arranged as a pouch as shown in Figure 2 and, the actuating member may be provided. By a rotating element configured to wind in at least a part of the flexible wall, thereby to constrict the pouch (by winding in the flexible wall to reduce its size) . Other arrangements without a holder or frame are also contemplated.

Figure 5 illustrates one arrangement which does comprise a frame, this apparatus is the same as that described with reference to Figure 1. However, unlike that arrangement, the flexible wall is connected between the frame 14 and a rotating actuating member 24.

This rotating actuating member 24 may comprise rollers able to wind in and wind out the flexible wall 16. It can be seen in Figure 5 that the rollers 24 are operable to wind in at least a part of the flexible wall 16, thereby to constrict the internal volume of the container. They are also operable to wind the flexible wall 16 out again so as to increase the internal volume. By such operation the apparatus illustrated in Figure 5 is operable selectively to jam and to un j am the jammable material held in the container.

The container may comprise a rigid wall 14, and the flexible wall 16 may be fixed to this rigid wall 14, e.g. , fixed at at least one side of the container. Another side of the flexible wall 16 may be connected to the rotatable actuating member 24.

Thus, as the flexible wall 16 is wound in by the actuating member 24 it presses the jammable material 18 together more tightly.

To unjam the jammable material 18, the direction of the rollers 24 can be reversed to pay out the flexible wall, thereby to relax it and unjam the jammable material 18.

The embodiments which have been described so far are relate to the possibility of relative movement between the actuating member 12 and the flexible wall 16. However, an actuating member 12 is optional, and one possibility which does not use an actuating member is shown in Figure 4A.

The apparatus 100 shown in Figure 4A comprises a container provided, at least in part, by a flexible wall 16. The flexible wall 16 encloses a jammable material 180 in the container. Adjacent to this container is a controllable magnetic element 200, which is operable to vary the magnetic field inside the container. The controllable magnetic element 200 illustrated in Figure 4A comprises an electromagnet, coupled to a controller configured selectively to energise the electromagnet to control the magnetic field in the internal volume of the container. This may enable the magnetic field to be switched between a relatively high field state and a relatively low field state (e.g. , when the electromagnet is off) . The jammable material 180 in this example comprises magnetic elements, such as ferrous material or other magnetizable material.

One possible material may comprise iron filings.

The jammable material 180 and the controllable magnetic element 200 together are configured so that, in the high field state, the magnetisation of the jammable material 18 causes it to jam. Conversely, in the low field state the jammable material 180 unj ams .

In operation, when the magnetic field provider 200 is operated to increase the magnetic field in the internal volume to the high field state, the magnetizable elements in the jammable material 180 become magnetised and stick together. This causes the jammable material 180 to increase its apparent hardness and/or stiffness.

The flexible wall 16 may be arranged so that it conforms closely to the jammable material 180 so that changes in the hardness or stiffness of the jammable material are more readily apparent at a touch surface coupled to the flexible wall. In some possibilities, the flexible wall 16 is resilient so that as the jammable material 180 jams and unjams the characteristics of the flexible wall 16 respond accordingly. The flexible wall 16 in such a system may be elastic and may be stretched around the jammable material 180 so as to further increase its responsiveness.

Figure 4B shows a further example 1000 in which the actuating member is provided by a controllably deformable element 220 which is coupled to the flexible wall 16 at locations selected so that deforming the deformable element 220 causes the shape and/or size of the internal volume to change. This provides an alternative way to control jamming of the jammable material 18. In this example, the controllably deformable element 220 may be connected to the flexible wall 16 at at least two locations, spatially separated on the flexible wall. In the example shown in Figure 4B, the controllably deformable element 220 may be an elongate element, such as a rod or wire.

Such an elongate element may be anchored to the flexible wall 16 at its ends, and/or at intermediate locations between its ends. One way to provide a controllably deformable element is by the use of shape memory alloys or other electromechanical actuators.

Such actuators may be integrated into the flexible wall.

In operation, the electromechanical actuator 220 may initially be in an in a relaxed state in which the flexible wall 16 is arranged so that the internal volume is sufficiently large to accommodate the jammable material in an un ammed state.

Application of electrical or thermal energy may then cause the deformable element to deform. As it deforms, because it is connected to the flexible wall at at least two locations, then the flexible wall is also deformed. For example, this may cause separated locations on the flexible wall to be drawn together, for example to cause the flexible wall to bunch, and wrinkle. This may reduce the extent of the flexible wall and constrict the internal volume to press the jammable material together. The deformable element may be configured to press the jammable material together enough to cause it to jam into a solid state.

This is illustrated in the second drawing of Figure 4B

Figure 6 shows yet a further example of an interface apparatus according to the present disclosure. In this example, a flexible wall 16 provides a container and surrounds the jammable material 18, for example, the flexible wall 16 may be in the form of a pouch. Part of this flexible wall 16 may be fixed in position, such as by a frame 14.

The actuating member 12 may be provided by an expandable element, such as a balloon. In this example, the actuating member 12 is movable by expansion and contraction of the actuating member itself. For example, at least one conduit 12-1 may be provided for supplying fluid into the expandable element 12 to cause it to inflate, the at least one conduit may also be controllable to hold the fluid in the expandable element to keep it inflated, and may be controllable to permit the fluid to leave the expandable element to deflate it. The possibility to keep the fluid in the balloon and to permit it to leave may be provided by control of a valve in or connected to such a conduit. It may also be provided by the application of fluid pressure to the conduit (such as by a pump) . The expandable member may comprise an extensible wall, configured to permit such expansion and the extensible wall may be elastic.

It can be seen in Figure 6 that the expandable member 12 is enclosed within the container which is provided by the flexible wall 16. The jammable material 18 is provided between the flexible wall 16 and the expandable element 12.

In operation, with the expandable element 12 in a first unexpanded state as illustrated in Figure 6A, the touch surface 11 may initially be in a relatively softer state because the internal capacity of the container provided by the flexible wall 16 is large enough to accommodate both the unexpanded expandable element 12 and the jammable material 18 in an unjammed state.

Then to cause the touch surface 11 to harden or stiffen, fluid is supplied into the expandable element 12 to cause it to inflate. This decreases the space available for the jammable material 18 until it causes the jammable material to jam and the touch surface 11 to take on a relatively harder state. This may take place when the expandable element 12 is sufficiently inflated and the flexible element is unable to move further to accommodate the jammable material 18, for example because it is at least partially inextensible and/or is less able to expand than the expandable element .

To cause the interface apparatus to remain in the relatively harder state, fluid can simply be held in the expandable element 12, such as by operation of a valve.

To cause the interface apparatus to return to the relatively softer state, the fluid may be allowed to leave the expandable element 12, such as by opening a valve and allowing the fluid to drain away .

Instead of using a valve, the fluid may be controlled by pumping. Two separate conduits may be provided, one to allow fluid to be provided into the expandable element and one to allow it to leave. The arrangement illustrated in Figure 6 comprises a frame 14 to which the flexible wall 16 is fixed, but this is optional. Typically the fluid used for control of the apparatus shown in Figure 6 is an incompressible fluid such as a liquid, and generally this fluid is non- j ammable .

In view of the foregoing disclosure, it will be appreciated that the present invention provides a wide variety of different ways in which non pneumatic jamming of jammable material may be provided. Whether this is done by relative movement between an actuating member and a flexible wall, or by the application of magnetic field, or by the use of deformable element (s) configured to deform to cause the flexible wall to deform does not matter. Each of these alternative solutions serves to address a related technical problem in that jamming of the jammable material may be provided by mechanical, as opposed to pneumatic, jamming of the jamming material .

The inventors have found that such mechanical actuation of jammable material may provide extremely fast response times and thereby improve operation of haptic interfaces.

Such arrangements may allow simpler and more effective control of a complex interface - there is no need to route and to control independently an array of pneumatic cells. Simple mechanical or electrical energy can be applied more easily. Mechanisms for this purpose will be apparent to the skilled person in view of the present disclosure.

It will also be appreciated that, typically, the flexible wall described herein may be inelastic, or at least may comprise substantially inextensible portions, so that the mechanical force or other jamming action can more effectively constrain the internal volume to cause the material to jam. The flexible wall may be provided by a textile or fabric, or by any other appropriate material arranged to provide a sheet-like element which may be arranged in any of the configurations described or claimed herein.

A variety of different jammable materials may be used. In addition to the magnetizable elements described above the jammable material may comprise a plurality of thermally conductive elements, arranged to so that, when the jammable material is jammed together, the apparent thermal conductivity of the material in the volume increases. This may be used to modulate the temperature of the touch surface. For example, heat may be applied to one or more locations in the jammable material, and the temperature of the touch surface may be modulated by jamming the material to mediate this heat to the touch surface. A system may be used to provide mechanical force to the drivers which operate the actuating members described and claimed herein . One example is an electric motor , such as a brushed DC motor . Gearing may be used to increase the torque applied by such motors . In an example which has been tested an electric motor was arranged to drive a rotatable actuating member such as that described with reference to Figure 2 by use of a reducing gearbox . An encoder , such as a magnetic encoder , may be used to enable closed-loop position control of the motor and to of fer more accurate setting of the extent to which the j ammable material i s to be compres sed ( and hence the hardnes s of the touch surface ) . Such device may be controlled by any appropriate microcontroller . One such system may implement a PID algorithm . Corresponding arrangements may be provided for linear actuators as appropriate .

It will be appreciated from the di scus sion above that the embodiments shown in the Figures are merely exemplary, and include features which may be generali sed, removed or replaced as described herein and as set out in the claims . With reference to the drawings in general , it will be appreciated that schematic functional block diagrams are used to indicate functionality of systems and apparatus described herein . It will be appreciated however that the functionality need not be divided in thi s way, and should not be taken to imply any particular structure of hardware other than that described and claimed below . The function of one or more of the elements shown in the drawings may be further subdivided, and/or di stributed throughout apparatus of the di sclosure . In some embodiments the function of one or more elements shown in the drawings may be integrated into a single functional unit .

In some examples the functionality of the microcontroller described herein may be provided by a general purpose proces sor , which may be configured to perform a method according to any one of those described herein . In some examples the controller may compri se digital logic , such as field programmable gate arrays , FPGA, application specific integrated circuits , ASIC , a digital signal proces sor , DSP , or by any other appropriate hardware . In some examples , one or more memory elements can store data and/or program instructions used to implement the operations described herein . Embodiments of the di sclosure provide tangible , non-transitory storage media comprising program instructions operable to program a proces sor to perform any one or more of the methods described and/or claimed herein and/or to provide data processing apparatus as described and/or claimed herein . The controller may compri se an analogue control circuit which provides at least a part of thi s control functionality . An embodiment provides an analogue control circuit configured to perform any one or more of the methods described herein .

The above embodiments are to be understood as illustrative examples . Further embodiments are envi saged . It i s to be understood that any feature described in relation to any one embodiment may be used alone , or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments , or any combination of any other of the embodiments . Furthermore , equivalents and modi fications not described above may al so be employed without departing from the scope of the invention, which i s defined in the accompanying claims .

Claims

1. A haptic interface apparatus (10) for the provision of haptic feedback via a touch surface (11) , the haptic interface comprising: an actuating member (12) ; a container (14) comprising a flexible wall (16) ; and a jammable material (18) held, by the flexible wall, in an internal volume of the container; wherein the flexible wall (16) and the actuating member (12) are configured for relative movement thereby to modify the internal volume to control jamming of the jammable material (18) , wherein haptic feedback at the touch surface (11) is based on control of the flexible wall (16) due to said jamming.

2. The haptic interface apparatus of claim 1 wherein said relative movement comprises the actuating member (12) pressing the jammable material together.

3. The haptic interface apparatus of claim 1 or 2 wherein said relative movement comprises the actuating member (12) moving to selectively reduce or increase the internal volume.

4. The haptic interface apparatus of any preceding claim wherein the actuating member (12) and/or the flexible wall (16) are configured so that the relative movement comprises a relative linear displacement.

5. The haptic interface apparatus of any preceding clam wherein the flexible wall (16) is fixed in position.

6. The haptic interface apparatus of claim 5 comprising a driver (20) , connected to the actuating member for forcing the actuating member to perform said relative movement, for example wherein the driver comprises a pusher such as an eccentric cam or a shaft.

7. The haptic interface apparatus of any of claims 1 to 4 wherein the actuating member is fixed in position.

8. The haptic interface apparatus of claim 7 wherein the relative movement comprises selective retraction of the flexible wall (16) .

9. The haptic interface apparatus of claim 7 or 8 comprising a driver (22, 24) , connected to the flexible wall and configured to cause said relative movement by selective application of tensile force to the flexible wall.

10. The haptic interface apparatus of any preceding claim wherein the actuating member provides an actuatable wall (26) of the container and the relative movement advances the actuatable wall (26) into a volume surrounded by the flexible wall, for example wherein the relative movement comprises a displacement along an axis of the container, for example wherein the flexible wall forms an elongate tube and the axis is the axis of the tube.

11 . The haptic interface apparatus of claim 1 wherein the flexible wall is held by the actuating member , such that the actuating member can apply force to the flexible wall to reduce the internal volume .

12 . The haptic interface apparatus of claim 11 wherein reducing the internal volume compri ses constricting the internal volume using the flexible wall .

13 . The haptic interface apparatus of claim 11 or 12 wherein reducing the internal volume compri ses twi sting at least a part of the container , such as by twisting the flexible wall , for example to twi st part of the flexible wall around the j ammable material .

14 . The haptic interface apparatus of any of claims 11 to 13 wherein the apparatus comprises a holder and the flexible wall i s fixed to the holder .

15 . The haptic interface apparatus of any of claims 11 to 14 wherein the actuating member i s configured to wind in at least part of the flexible wall to constrict the internal volume .

16 . The haptic interface apparatus of any of claims 11 to 15 wherein the actuating member is connected to a driver configured to cause the actuating member to rotate to apply said force to the flexible wall, for example by winding it in or by twisting it.

17. The haptic interface apparatus of claim 3 wherein the actuating member (12) comprises an expandable element which is controllable to expand and contract to selectively reduce or increase the internal volume.

18. The haptic interface of any preceding claim wherein the flexible wall comprises substantially inextensible portions arranged to cause said jamming, for example wherein the flexible wall is substantially inextensible.

19. The haptic interface of any preceding claim wherein the flexible wall comprises substantially inelastic portions, for example wherein the flexible wall is substantially inelastic, for example wherein at least a portion of the flexible wall consists essentially of an inelastic material.

20. A haptic interface apparatus (100) for the provision of haptic feedback via a touch surface (11) , the haptic interface comprising: a container comprising a flexible wall (16) ; and a jammable material (180) held, by the flexible wall (16) , in an internal volume of the container; a magnetic field provider (200) , configured to provide controllable magnetic field in the internal volume; wherein the jammable material (180) comprises magnetisable elements thereby to enable the magnetic field provider to control jamming of the jammable material by varying the magnetic field in the internal volume, wherein haptic feedback at the touch surface is based on control of the flexible wall due to said jamming.

21. The haptic interface apparatus of claim 20, wherein the magnetic field provider comprises an electromagnet.

22. The haptic interface apparatus of claim 20 or 21 wherein the magnetic field provider comprises a permanent magnet and a mover, arranged to move the permanent magnet to control the magnetic field in the internal volume.

23. The haptic interface apparatus of any of claims 20 to 22 wherein the magnetisable elements comprise ferromagnetic and/or ferrimagnetic material.

24. The haptic interface apparatus of any of claims 20 to 23 wherein the flexible wall is resilient.

25. The haptic interface apparatus of claim 24 wherein the flexible wall comprises an elastic material.

26. The haptic interface apparatus of claim 24 or 25 wherein the flexible wall is resiliently deformed to accommodate the internal volume .

27. A haptic interface apparatus (1000) for the provision of haptic feedback via a touch surface (11) , the haptic interface comprising : a container comprising a flexible wall (16) ; and a jammable material (18) held, by the flexible wall, in an internal volume of the container; wherein a controllably deformable element (220) is coupled to the flexible wall at locations selected so that deforming the deformable element (220) causes the shape and/or size of the internal volume to change to control jamming of the jammable material , wherein haptic feedback at the touch surface is based on control of the flexible wall due to said jamming.

28. The haptic interface apparatus of claim 27 wherein the controllably deformable element (220) comprises an electromechanical actuator.

29. The haptic interface apparatus of claim 27 or 28 wherein the controllably deformable element comprises a shape memory alloy

(SMA) .

30. The haptic interface apparatus of any of claims 27 to 29 wherein the controllably deformable element is provided in the flexible wall.

31. The haptic interface apparatus of any preceding claim wherein the jammable material comprises at least one of: a plurality of particles; a plurality of fibres; and a plurality of laminar elements .

32. The haptic interface apparatus of any preceding claim wherein the jammable material is configured such that jamming the jammable material causes a change in thermal conductivity of the jammable material, for example wherein the jammable material comprises a plurality of thermally conductive elements configured such that jamming them together increases the thermal conductivity of the jammable material.

33. The haptic interface apparatus of any preceding claim wherein the jammable material comprises compressible elements, for example resilient foam elements.

34. The haptic interface apparatus of any preceding claim wherein haptic feedback at the touch surface comprises at least one of:

(i) control of apparent stiffness of the flexible wall;

(ii) control of temperature of the flexible wall;

(iii) control of shape of the flexible wall; and ( iv) vibration of the flexible wall .

35 . A haptic interface system compri sing a plurality of haptic feedback elements , each haptic feedback element compri sing a haptic interface apparatus according to any preceding claim wherein the touch surface of each haptic interface apparatus i s configured to provide a part of a haptic feedback of the haptic interface system.

36 . The haptic interface system of claim 35 wherein the haptic feedback elements are spatially arranged to provide di f ferent component parts of a multicomponent feedback, for example wherein the haptic feedback elements are arranged in an array .

37 . The haptic interface of any of claims 27 to 36 wherein the flexible wall comprises substantially inextensible portions arranged to cause said j amming, for example wherein the flexible wall i s substantially inextensible .

38 . The haptic interface of any of claims 27 to 37 wherein the flexible wall compri ses substantially inelastic portions , for example wherein the flexible wall i s substantially inelastic , for example wherein at least a portion of the flexible wall consi sts es sentially of an inelastic material .