Patent Application
20240188659
The present invention relates to a wearable article that provides haptic feedback to a user, in particular to a haptic glove. The present invention in particular relates to such haptic gloves using shape memory alloy (SMA) wires for providing haptic feedback. The present invention also relates to a latch, for example for use in the haptic glove.
Haptic gloves may be used to provide haptic or tactile feedback to a user's hand, for example when used in combination with virtual reality (VR) or augmented reality (AR) technology. Haptic gloves may provide a variety of sensations to a user's hand, ranging from giving the impression of gripping a virtual object (e.g. in a video game) to imitating texture and other surface structure on such a virtual object. Existing haptic gloves, however, are still limited in their capability of providing accurate haptic feedback and tracking a user's hand movement. Additionally, the mechanisms driving existing haptic gloves are large and heavy, limiting the adoption of haptic gloves in VR applications.
According to the present invention, there is provided a haptic glove for providing haptic feedback to a user's hand, the haptic glove comprising: a base portion and one or more finger portions extending from the base portion, wherein each finger portion is pivotally movable relative to the base portion, and one or more cables, each comprising a distal end connected to a respective finger portion and a proximal end extending towards the base portion; and one or more cable control assemblies, at least one (optionally each) cable control assembly comprising: a constrain mechanism configured, when engaged, to constrain movement of the proximal end of a respective cable relative to the base portion, thereby constraining movement of a respective finger portion relative to the base portion, and an SMA wire arranged, on contraction, to engage or disengage the constrain mechanism.
Due to its high energy density, SMA wire may be used as an actuator in particularly compact applications, reducing the size of the cable control assembly. The SMA wire, on contraction, selectively engages or disengages the constrain mechanism to or from the cable. The SMA wire may be powered or energized to contract, for example by passing an electrical power through the SMA wire. On elongation, e.g. due to an opposing biasing force of a biasing element (such as a resilient element, e.g. a spring or a magnet) or of an opposing SMA wire, the SMA wire respectively disengages or engages the constrain mechanism from or to the cable. This selectively constrains movement of the cable and thus the finger portion, providing haptic feedback to a user.
The constrain mechanism be coupled or connected (e.g. via one or more movable and/or intermediary parts) to the cable on contraction of the SMA wire, such that the constrain mechanism affects (i.e. constrains) movement of the cable. The constrain mechanism may be decoupled or disconnected from the cable when the SMA wire is not contracted, such that the constrain mechanism does not affect (i.e. does not constrain) movement of the cable. Alternatively, constrain mechanism be decoupled or disconnected from the cable on contraction of the SMA wire, such that the constrain mechanism does not affect (i.e. does not constrain) movement of the cable. The constrain mechanism may be coupled or connected to the cable (e.g. via one or more movable and/or intermediary parts) when the SMA wire is not contracted, such that the constrain mechanism affects (i.e. constrains) movement of the cable.
In some embodiments, the at least one (optionally each) cable control assembly comprises a constrain mechanism in the form of a locking mechanism configured, when engaged, to prevent movement of the proximal end of the respective cable relative to the base portion. The cable may thus be prevented from moving on curling of a user's finger, e.g. due to a locking part locking the cable in place (e.g. via any movable parts connected to the cable).
In some embodiments, the at least one (optionally each) cable control assembly comprises a constrain mechanism in the form of a braking mechanism configured, when engaged, to apply a frictional force to the proximal end of the respective cable. The frictional force may be so as to prevent the cable from moving. Alternatively, the frictional force may be lower so as to allow some movement of the cable when a large external force is applied to the cable, e.g. by a user. In any case, the frictional force resists movement of the cable and so may provide haptic feedback. Optionally, the cable control assembly may vary the amount of engagement with the braking mechanism so as to vary the frictional force, for example within a continuous range or between multiple discrete levels. For example, the SMA wire may, on initial contraction, engage the brake mechanism such that a first frictional force resists movement of the cable, and on further contraction, engage the brake mechanism such that a second frictional force resists movement of the cable, where the second frictional force is different to (e.g. larger than) the first frictional force.
In some embodiments, the at least one (optionally each) cable control assembly comprises a constrain mechanism in the form of a spring mechanism configured, when engaged, to apply a bias force along the respective cable. The spring mechanism, when engaged, may apply tension to the respective cable. This may give the impression to a user of the haptic glove of pulling a trigger or squeezing an elastic ball, for example. The spring mechanism may thus provide a further, different haptic sensation to the locking or brake mechanisms, thus further improving haptic feedback achievable by the haptic glove.
In some embodiments, the at least one (optionally each) cable control assembly comprises constrain mechanisms in the form of i) the spring mechanism and ii) at least one of the locking and braking mechanism. This enables improved haptic feedback compared to situations in which just one of these constrain mechanisms is provided. In some further embodiments, the at least one (optionally each) cable control assembly comprises constrain mechanisms in the form of i) the spring mechanism and ii) the locking mechanism and iii) the braking mechanism.
In some embodiments, the at least one cable control assembly (optionally each) comprises at least two SMA wires, wherein one SMA wire is arranged selectively to engage or disengage the locking or braking mechanism and another SMA wire is arranged selectively to engage or disengage the spring mechanism. So, the spring mechanism and the locking or braking mechanisms are independently controllable. In some alternative embodiments, the at least one cable control assembly comprises an SMA wire arranged, on initial contraction, to i) engage the spring mechanism or ii) disengage the locking or braking mechanism and, on further contraction, to respectively i) engage the locking or braking mechanism or ii) disengage the spring mechanism.
This SMA wire may form part of a multi-stage latch, for example, such that
This allows a single SMA wire to selectively engage or disengage at least two constrain mechanisms. In embodiments in which three or more separate constrain mechanisms are provided, a single SMA wire (optionally in a multi-stage latch) may be used to selectively engage or disengage the three or more separate constrain mechanisms in equivalent manner.
In some embodiments, the at least one cable control assembly comprises a retraction mechanism configured to permanently apply a retracting bias force along the cable. The retraction mechanism may be embodied by a resilient element, such as a spring (e.g. torsion spring), for example. The retraction mechanism may remain connected to the cable at all times, so as to put tension on the cable at all times. The spring mechanism, when engaged, provides additional tension to the cable and so provides haptic feedback even when the retraction mechanism is engaged. Preferably, the spring mechanism provides a bias force that is at least equal to the bias force of the retraction mechanism.
In some embodiments, the at least one cable control assembly comprises a movable part that is coupled to the proximal portion of the cable. The movable part may be connected or coupled to the cable at all times. The movable part may be rotatably movable, e.g. about an axis or pivot, or may be translationally movable. The movable part may move with the cable.
In some embodiments, the movable part comprises a reel and the cable is wound on the reel. A reel provides a particularly compact arrangement for large movement of the proximal portion of the cable.
In some embodiments, the reel is a multi-diameter reel comprising portions with different diameters, and different cables are wound on the portions of the reel with different diameters.
In some embodiments, each finger portion comprises a plurality of finger segments, and different cables are connected at their distal ends to different finger segments of a respective finger portion, wherein the different cables are wound on parts of the reel with different diameters. Movement of the cables connected to the finger segments of a single finger portion may thus be geared. This allows the multiple cables to be controlled using a single cable control mechanism, simplifying control.
In some embodiments, the at least one cable control assembly comprises an intermediary part, and wherein the SMA wire is arranged to move the intermediary part so as to engage or disengage the constrain mechanism. Movement of the intermediary part may selectively connect or couple, or disconnect or decouple, the cable (e.g. via the movable part) from the constrain mechanism.
In some embodiments, the intermediary part is arranged to pivot so as to engage or disengage the constrain mechanism. This makes control of the position of the intermediary part particularly reliable, providing improved engagement and disengagement of the constrain mechanism.
In some embodiments, the SMA wire is coupled to the intermediary part via a resilient element. This may reduce the risk of damage to the SMA wire due to large external loads on the cable, which may be absorbed by the resilient element instead of the SMA wire. Furthermore, it may improve engagement or disengagement of the constrain mechanism, for example when the intermediary part comprises teeth for engaging complimentary teeth on the movable part or other part for connecting or coupling the cable to the constrain mechanism.
In some embodiments, the SMA wire is arranged to move the intermediary part into or out of engagement with the movable part so as to engage or disengage the constrain mechanism. Alternatively, the intermediary part may be in constant connection with the movable part, and the SMA wire may move the intermediary part into or out of engagement with a portion of the constrain mechanism (e.g. with the base portion or a part connected to a spring).
In some embodiments, the intermediary part and the movable part comprise engagement surfaces for engaging each other, wherein the engagement surfaces are configured, on engagement, to constrain sliding between the intermediary part and the movable part. Each engagement surface may comprise a plurality of complementary teeth, thus improving reliable coupling and suppressing sliding.
In some embodiments, the cable control assembly comprises a latch, the latch comprising a latching part movable between a latched position and an unlatched position, and wherein the SMA wire is arranged, on contraction, to move the latching part into the latched position, thereby engaging or disengaging the constrain mechanism. In some embodiments, a release SMA wire is arranged, on contraction, to move the latching part into the unlatched position, thereby respectively disengaging or engaging the constrain mechanism. The release SMA wire may move a release part so as to move the latching part into the unlatched position, for example. The latch is configured to remain in the latched or unlatched position when the SMA wire ceases to be energized. As such, energy consumption of the cable control assembly is reduced compared to a situation in which the SMA wire needs to be continuously powered to keep the constrain mechanism engaged or disengaged.
In some embodiments, the latch comprises a support structure comprising first and a second surface separated by a step, a latching part slidable along the first and/or second surfaces between the unlatched position engaging the first surface and the latched position engaging the step and second surface, and a biasing element arranged to bias the latching part against the step and the first and/or second surfaces, wherein the SMA wire is arranged, on contraction, to move the latching part along the first surface into the latched position under bias of the biasing element so as to engage or disengage the constrain mechanism. A release SMA wire may be arranged, on contraction, to move the latching part over the step into the unlatched position under bias of the biasing element. The release SMA wire may move a release part so as to move the latching part into the unlatched position, for example.
In some embodiments, the support structure comprises a second set of first and second surfaces separated by a second step, and wherein the latch further comprises: a second latching part slidably arranged along the second set of first and/or second surfaces between an unlatched position engaging the respective first surface and a latched position engaging the respective step and second surface, and a second SMA wire arranged, on contraction, to move the second latching part along the respective first surface into the latched position under bias of the second biasing element; wherein the latching part in its latched position is arranged to engage or disengage a first constrain mechanism, and the second latching part in its latched position is arranged to engage or disengage a second constrain mechanism, and wherein the release SMA wire is arranged, on contraction, to move both the latching part and the second latching part over the respective step into the respective unlatched position under bias of the respective biasing element.
As such, the latch is capable or selectively engaging or disengaging different constrain mechanism, for example the spring mechanism and one or the locking or braking mechanisms. A single SMA wire may be used to selectively disengage both constrain mechanisms.
In some embodiments, the support structure comprises a third surface separated from the second surface by a second step, wherein the latching part is slidably arranged along the first, second and/or third surfaces between the unlatched position engaging the first surface, a first latched position engaging the step and second surface and a second latched position engaging the second step and the third surface. As such, the latch may be a multi-stage latch. The multi-stage latch may adjust the frictional force of the braking mechanism, for example. The multi-stage latch may alternatively allow engaging of different constrain mechanism, for example.
In some embodiments, the release SMA wire is arranged to move the latching part from either of the first or second latched positions into the unlatched position under bias of the biasing element. As such, only a single SMA wire is required to release the latch.
In some embodiments, the release SMA wire is arranged, on initial contraction, to move the latching part from the second latched position over the second step into the first latched position under bias of the biasing element, and, on further contraction, to move the latching part from the first latched position over the first step into the unlatched position under bias of the biasing element.
According to the present invention, there is also provided a latch comprising a support structure comprising first and a second surface separated by a step, a latching part slidable along the first and/or second surfaces between an unlatched position engaging the first surface and a latched position engaging the step and second surface, and a biasing element arranged to bias the latching part against the step and the first and/or second surfaces, and an SMA wire arranged, on contraction, to move the latching part along the first surface into the latched position under bias of the biasing element. So, the latch described herein may form part of the present invention in isolation of the features of the haptic glove.
In some embodiments, the latch comprises a release SMA wire arranged, on contraction, to move the latching part over the step into the unlatched position under bias of the biasing element
In some embodiments, the support structure comprises a second set of first and second surfaces separated by a second step, and wherein the latch further comprises: a second latching part slidably arranged along the second set of first and/or second surfaces between an unlatched position engaging the respective first surface and a latched position engaging the respective step and second surface, and a second SMA wire arranged, on contraction, to move the second latching part along the respective first surface into the latched position under bias of the second biasing element.
In some embodiments, the release SMA wire is arranged, on contraction, to move both the latching part and the second latching part over the respective step into the respective unlatched position under bias of the respective biasing element.
In some embodiments, the support structure comprises a third surface separated from the second surface by a further step, wherein the latching part is slidable along the first, second and/or third surfaces between the unlatched position engaging the first surface, a first latched position engaging the step and second surface and a second latched position engaging the further step and the third surface.
In some embodiments, the release SMA wire is arranged to move the latching part from either of the first or second latched positions into the unlatched position under bias of the biasing element.
In some embodiments, the release SMA wire is arranged, on initial contraction, to move the latching part from the second latched position over the second step into the first latched position under bias of the biasing element, and, on further contraction, to move the latching part from the first latched position over the first step into the unlatched position under bias of the biasing element.
Certain embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
The haptic glove 1 further comprises one or more cables 30 that is or are coupled at one end (herein referred to as the “distal end”) to a respective finger portion 20. Multiple cables 30 may be provided per finger portion 20, as described in more detail below. The cable 30 may be any elongate element capable of carrying a tensile force. The cable 30 may be deformed by forces acting laterally to the tensile force carried by the cable 30.
The cable 30, in particular movement of the cable 30, is controlled by a cable control assembly 100. The cable control assembly 100 may control the cable 30 passively, i.e. the cable control assembly 100 may selectively constrain (i.e. resist by a frictional force or bias force, or even prevent) movement of the cable 30. The cable control assembly 100 need not actively move the cable 30. In some embodiments, however, the cable control assembly 100 may actively pull on the cable 30 so as to move the finger portion 20 relative to the base portion 10.
The cable control assembly 100 may be provided on the base portion 10, as schematically shown. However, in general, the cable control assembly 100 may also be provided on the finger portions 20, or be distributed between the base portion 10 and the finger portions 20. The end of the cable 30 that is not coupled to the finger portion 20 (herein referred to as the “proximal end” or “proximal portion”) may be coupled to the cable control assembly 100. The cable control assembly 100 may provide haptic feedback to a user by constraining, i.e. resisting or even preventing, movement of the cable 30. Details and embodiments of the cable control assembly 100 are described below.
The cable control assembly 100 may comprise at least one constrain mechanism 120, for example in the form of a locking mechanism 120a, a braking mechanism 120b and/or a spring mechanism 120c. The cable control assembly 100 may selectively engage the constrain mechanism 120. So, the constrain mechanism 120 may selectively constrain movement of the cable 30 relative to the base portion 10. This selectively locks, brakes or otherwise resists (e.g. applies a force that opposes) movement of the finger portion 20 relative to the base portion 10, thereby providing haptic feedback to the user.
Optionally, the cable control assembly 100 comprises at least one retraction mechanism 110. The retraction mechanism 110 may retract the cable 30, for example upon un-bending of the finger portions 20. The retraction mechanism 110 may provide a continuous or permanent biasing force for retracting the cable 30. The retraction mechanism 110 may be embodied by a resilient element, such as a spring (e.g. compression or tension spring, or a torsion spring) that provides the biasing force. In some embodiments, a dedicated retraction mechanism 110 is not provided.
Optionally, the cable control assembly 100 may comprise a multi-cable coupling 170, thereby enabling multi-cable control. So, some provision may be made for the cable control assembly 100 to control multiple cables 30 simultaneously. Each or at least one of the retraction mechanism 110 and/or the constrain mechanism 120 may thus act on multiple cables 30 simultaneously, such that a single retraction mechanism 110 and/or constrain mechanism 120 may act on multiple cables 30. This may make the cable control assembly 100 more compact and simpler. Alternatively, the cable control assembly 100 may control each cable 30 independently. Each retraction mechanism 110 and/or the constrain mechanism 120 may thus act on a single cable 30 only, such that a dedicated retraction mechanism 110 and/or constrain mechanism 120 is provided for each cable 30. This may provide more accurate cable control, and thus improved haptic feedback.
Optionally, the cable control assembly 100 comprises a position sensing arrangement 190. The position sensing arrangement 190 may determine a position of a finger portion 20 relative to the base portion 10. The position sensing arrangement 190 may, for example, determine the position of the cable 30 relative to the base portion 20. A processor (not shown) or other control circuit may receive the position data and make a determination as to whether or not to provide haptic feedback at least in part based on the position data.
Optionally, the haptic glove 1 comprises one or more haptic actuators 200 for providing localized haptic feedback to a user. The one or more haptic actuators 200 may be provided on the finger portion 20 (for example near the fingertip of a user), to selectively provide a localized haptic sensation to a specific portion of the user's hand (for example to the fingertip of the user).
Details of the haptic glove 1 are described below. It will be appreciated that any of the embodiments of the structure of the base portion 10 and/or finger portion 20 may be combined with any of the embodiments of the cable control assembly 100 described below. Furthermore, even though the parts of the cable control assembly 100 are described below in relation to the haptic glove 1, it will be appreciated that these parts may find application in devices other than the haptic glove and may form embodiments of the present invention in their own right. Specifically, aspects of the constrain mechanism 120, including the locking mechanism 120a, the braking mechanism 120b and the spring mechanism 120c, as well as the latch mechanisms described below, need not be coupled to a cable 30 and/or a haptic glove 1 and may thus form inventions separate from the haptic glove 1 described herein.
The base portion 10 is arranged, in use, to at least partially be arranged adjacent to a user's hand. Although not shown, the base portion 10 may extend over the wrist of a user's hand, thus providing additional space for other components of the haptic glove 1. In its simplest form, the base portion 10 may comprise a plate provided on the rear of a user's hand. The base portion 10 may be fixed relative to a user's hand, for example using suitable straps. The base portion 10 may also be worn on the user's hand, so as to partially or entirely surround a user's palm.
One or more (e.g. four or five) finger portions 20 may depend from the base portion 10. The finger portion 20 comprises a proximal end arranged next to the base portion 10 and a distal end arranged away from the base portion 10. Each finger portion 20 is to be arranged on or adjacent to a user's finger (where the thumb is considered to be one of the fingers). Each finger portion 20 may be pivotally arranged relative to the base portion 10, i.e. the distal end of each finger portion 20 may pivot relative to the base portion 10. The finger portion 20 may pivot or bend relative to the base portion 10 at least in a direction substantially orthogonal to a user's palm, so as to allow bending of the user's finger. The finger portion 20 may additionally be laterally movable relative to the base portion 10, i.e. in a plane substantially parallel to a user's palm, so as to allow for lateral movement of a user's finger. This avoids constraining natural movement of a user's finger, making the haptic glove 1 more comfortable to wear and providing a more natural feel to a user.
The haptic glove 1 may comprise five finger portions 20, one for each finger of a user's hand. In some embodiments, the haptic glove 1 may comprise fewer than five finger portions 20, for example four finger portions 20 (for surrounding a user's fingers other than the thumb) or fewer finger portions 20. In some embodiments, a finger portion 20 may be provided to be worn on multiple fingers. For example, a single finger portion 20 may be worn on the pinkie finger and ring finger of a user's hand together, such that the pinkie finger and ring finger move together.
In preferred embodiments, each finger portion 20 comprises one or more segments 22, e.g. a plurality of segments 22 mechanically connected in series so as to form a chain of linkages. The segments 22 may be pivotally movable with respect to each other and with respect to the base portion 10, so as to allow bending and/or curling of a user's finger while remaining adjacent to the user's finger. One or more bearings 23 may be provided between adjacent finger segments 22 and between the base portion 10 and the finger portion 20, so as to allow relative movement of the finger segments 22 relative to each other and relative to the base portion 10.
The haptic glove 1 comprises one or more cables 30. The haptic glove 1 may, for example, comprise one cable 30 per finger portion 20. This allows each finger portion 20 to be controlled independently.
In some embodiments, the haptic glove 1 comprises more than one cable 30 per finger portion 20, for example one cable 30 per phalanx of a user's finger. So, the haptic glove 1 may comprise two cables 30 per finger portion 20 corresponding to a thumb of a user, and three cables 30 per finger portion 20 corresponding to another finger of a user.
As described above, controlling (in particular constraining) movement of the cable 30 (in particular of the proximal portion of the cable 30) may be used to provide haptic feedback to a user's hand. The figures described below schematically depict various aspects of the cable control assembly 100. The cable control assembly 100 may comprise or embody one or more of a retraction mechanism 110 for retracting the cable 30, a locking mechanism 120a for locking the proximal portion of the cable 30 in place, a brake mechanism 120b for braking movement of the proximal portion of the cable 30a, and a spring mechanism 120c for selectively applying a spring force to the proximal portion of the cable 30, in particular along the cable 30. A respective part of the cable control assembly 100 may be provided individually for each cable 30, or multiple cables 30 (e.g. all cables coupled to a finger portion 20) may be controlled by a single part of the cable control assembly 100, for example by coupling multiple cables using the multi-cable coupling 170. Described below are examples of parts of the cable control assembly 100 that achieve one or more of these functions.
According to the present invention, the cable control assembly 100 comprises a constrain mechanism 120. The constrain mechanism 120 is configured, when engaged, to constrain movement of the proximal end of a respective cable relative to the base portion, thereby constraining movement of a respective finger portion relative to the base portion. When the constrain mechanism 120 is disengaged movement of the proximal end of a respective cable relative to the base portion is not constrained by the constrain mechanism 120. The constrain mechanism 120 may be embodied by the locking mechanism 120a, the brake mechanism 120b and/or the spring mechanism 120c.
An SMA wire is arranged, on contraction, to engage or disengage the constrain mechanism 120.
The haptic glove 1 further comprises a cable control assembly 100. The cable control assembly 100 comprises a movable part 102 coupled to the proximal portion of the cable. The movable part 102 is arranged at the proximal end of the cable 30.
A constrain mechanism 120 is provided for selectively constraining movement of the proximal end of the cable 30. In the depicted embodiment, the constrain mechanism 120 is embodied by a locking or braking mechanism 120a,b in combination with a spring mechanism 120c. The constrain mechanism 120 is selectively engageable so as to provide haptic feedback.
Cable control assembly 100 comprises an intermediary part 124a,b and an SMA wire 128a,b. The intermediary part 124a,b is constrained from moving along the movement axis A. The SMA wire 128a,b, on contraction, moves the intermediary part 124a,b into engagement with the movable part 102, thereby constraining movement of the movable part 102 relative to the base portion 10. Using an SMA wire 128a,b may enable a particularly lightweight and compact mechanism. Although in the depicted embodiment the SMA wire, upon actuation (contraction) moves the intermediary part 124a,b into engagement, in alternative embodiments the SMA wire may move the intermediary part 124a,b out of engagement with the movable part 102.
Although not shown, the locking or braking mechanism 102 may further comprise a biasing element that biases the intermediary part 102 out of or into engagement with the movable part 102 or base portion 10. The SMA wire 128a,b is arranged, on actuation, to oppose the biasing force of the biasing element.
In further alternative embodiments, the intermediary part 124a,b may be constrained from moving along the movement axis relative to the movable part 102 (and so may move along the movement axis relative to the base portion 10). The intermediary part 124a,b may be brought into or out of engagement with the base portion 10 by the SMA wire 128a,b, thereby constraining movement of the movable part 102 relative to the base portion 10.
In the depicted embodiment, the SMA wire 128a,b is arranged to move the intermediary part 124a,b in a direction that is perpendicular to the movement axis A. In general, the SMA wire 128a,b may move the intermediary part 124a,b in any direction that is angled relative to the movement axis A.
In the depicted embodiment, the intermediary part 124a,b and the movable part 102 comprise engagement surfaces that are configured to engage each other. The engagement surfaces, on engagement, constrain sliding between the engagement surfaces. As depicted, each engagement surface may comprises a plurality of teeth, i.e. each engagement surface may be serrated. In such an embodiment, the constrain mechanism may act as a locking mechanism 120a, in that the movable part 102 may be locked in place when engaged by the intermediary part 124a. In general, however, the engagement surface may have any surface structure suitable for constraining relative sliding on engagement. The engagement surfaces may, for example, be relatively rough surfaces. In such an embodiment, the constrain mechanism may act as a braking mechanism 120b, in that the intermediary part 124b may brake movement of the movable part 102 when in engagement.
In the depicted embodiment, the two ends of the SMA wire 128 are fixed relative to the base portion 10. The SMA wire bends around a contact portion that is in contact with the intermediary part 124a,b, thereby forming two SMA portions on either side of the contact portion. The two SMA portions are angled relative to each other. Contraction of the SMA wire 128a,b (e.g. by driving the SMA wire 128a,b using a suitable drive current) urges the intermediary part 124a,b towards and into engagement with the movable part 102.
In alternative embodiments, the SMA wire 128a,b may be arranged differently to move the intermediary part 124a,b. For example, the SMA wire 128a,b may be connected between the intermediary part 124a,b and the base portion 10. Contraction of the SMA wire 128a,b thus directly moves the intermediary part 124a,b relative to the base portion 10. The intermediary part 124a,b may comprise a sliding surface that slidingly engages the base portion 10. The sliding surface may be angled relative to the movement axis A. The SMA wire may be arranged, on contraction, to move the intermediary part 124a,b along the sliding surface. Because the sliding surface is angled relative to the movement axis A, sliding along the movement axis A may bring the intermediary part 124a,b into or out of engagement with the movable part 102.
As shown in
When movement of the second movable part 122c relative to the base portion is constrained or even prevented, the first movable part 102 (and cable 30 connected thereto) may move against the spring force of the resilient element 123c. So, a spring force acts against movement of the first movable part 102 in the up-direction in
The cable control assembly 100 further comprises the intermediary part 124a,b and the second intermediary part 124c. When the intermediary part 124a,b is in engagement with the movable part 102, the proximal end of the cable 30 is constrained or even prevented from moving, giving the impression of holding a rigid object to the user, as explained above. When the second intermediary part 124c is in engagement with the second movable part 122c (and the intermediary part 124a,b is not in engagement with the movable part 102), moving the movable part 102 requires acting against the spring force of the resilient element 123c. This gives the impression of squishing an elastic object or pulling a trigger, as explained above.
Unlike in the embodiment depicted in
The embodiment of
As explained above, the haptic glove 1 may in some embodiments comprise more than one cable 30 per finger portion 20, for example one cable 30 per phalanx of a user's hand. The shape of the finger portion 20 can thus be more accurately controlled compared to providing a single cable 30 per finger portion 20, enabling improved haptic feedback.
In general, each cable 30 of the multiple cables 30 per finger portion 20 may be controlled independently, either within the same cable control assembly 100 or by different cable control assemblies 100.
The multiple cables 30 coupled to a finger portion 20 may move by proportional amounts. For example, with reference to
The multiple cables 30 may be coupled to one another to enable such proportional movement. This allows the multiple cables 30 per finger portion 20 to be controlled simultaneously. Control is thus simplified, because a single cable control assembly 100 may be used to control multiple cables 30.
The multi-diameter reel 175 comprises portions 175A-C with different diameters. Each portion 175A-C may be a cylinder or be considered a reel by itself. Different cables 30 are wound on portions of the reel with different diameters. The different cables 30 may be cables coupled to different finger segments 22 of the same finger portion 20, and so may be proportionally moved relative to each other. For example, a cable 30 coupled to a relatively distal finger segment 22 of the finger portion 20 (relative to the multi-diameter reel) may be wound on a relatively larger diameter portion 175C of the reel. A cable 30 coupled to a relatively proximal finger segment 22 of the finger portion 20 (relative to the multi-diameter reel) may be wound on a relatively smaller diameter portion 175A of the reel. This allows the cables 30 coupled to different finger segments 22 of the finger portion 20 to move proportionally, enabling the finger portion to allow a natural curling motion of a user's finger while simplifying control compared to a situation in which each cable 30 is controlled independently.
So, the portions of the reel 175 have different diameters, and allow for different movement of the different cables 30 relative to the base portion 10. Upon bending of a finger portion, for example, the proximal phalanx may bend less than the middle phalanx, which is turn bends less than the distal phalanx. As such, the cable 30 connected to the distal phalanx may move more relative to the base portion 10 than the cable connected to the middle phalanx and the cable connected to the proximal phalanx. The multi-cable coupling may apply gearing to the movement of the cables 30 relative to the base portion 10.
Another advantage of providing a reel on which the cable 30 is wound that relatively large cable movement is enabled within a relatively compact space. The excess cable length is neatly wound on the reel. In general, a single diameter reel may be provided to achieve these advantages without implementing multi-cable control 170.
The constrain mechanism 120 comprises a movable part 102 that is coupled to the proximal portion of the cable 30. The SMA wire 130 may, upon contraction, constrain movement of the movable part 102, thereby constraining movement of the cable 30.
The movable part 102 may be embodied by any part that is permanently coupled to the proximal portion of the cable 30. The movable part 102 may be any part that moves with the cable 30. In some embodiments, the movable part 102 is integrally formed with the cable 30 or is embodied by the proximal portion of the cable 30 itself.
In general, the movable part 102 may be any part that is movable with the cable 30. The movable part 102 may be rotationally movable (like the reel 175) or may be translationally movable (like the rack 102″). In general, the reel 175 of
The cable control mechanism 100 may comprise a retraction mechanism 110 for retracting the cable upon unbending of the finger portions. The retraction mechanism 110 may be embodied by any resilient element permanently coupled to the movable part 102 and capable of retracting the cable 30. Preferably, the resilient element is capable of retracting the cable 30 over the entire movement range of the cable 30.
The retraction mechanism may be embodied by a torsion spring, for example for applying a torque to the reel 175 for retracting the cable 30. The retraction mechanism 110 may alternatively be embodied by a tension or compression spring, for example coupled to a movable part in the form of a rack 102″ or the coupling cable 102′. The retraction mechanism 110 may also act directly on the cable, for example by a spring connected directly to the proximal end of the cable 30.
In the embodiments described in relation to
In some advantageous embodiments, a latch 200 is used to selectively engage and/or disengage the constrain mechanism 120. The latch assembly may require powering only during switching the constrain mechanism 120 into or out of engagement. The latch arrangement may not require power for keeping the constrain mechanism 120 engaged and disengaged.
The latch 200 comprises a support structure 210. The support structure 210 is used herein as a reference point, relative to which movement of other components of the latch 200 is described (unless otherwise indicated). When integrated into the haptic glove 1, the support structure 210 may be fixed relative to the base portion 10, for example by being fixedly attached to the base portion 10 or integrally formed with the base portion 10.
The latch 200 further comprises a latching part 220 and a biasing element 223. The latching part 220 is movably arranged relative to the support structure 210. The biasing element 223 biases the latch part 220 against the support structure 210.
The support structure 210 comprises a catching portion 211, in the form of a step 211 in
The latch assembly 200 further comprises an SMA wire 228a. The SMA wire 228 is arranged, on contraction, to move the latch part 220 from an unlatched position into a latched position in which the latch part 220 catches the catching portion 211 under action of the biasing element 223 such that movement of the latch part 220 is constrained.
In addition, the latch assembly 200 comprises a release mechanism for releasing the latch part 220 from the latched position into the unlatched position. The release mechanism releases the latch part 220 from the catching portion 211 of the support structure 210, such that the latch part 220 returns, under action of the biasing element 223, to the unlatched position.
With reference to
In general, the release mechanism may comprise any other mechanism for releasing the latch part 220 from the catching portion 211 of the support structure 210, such as any mechanism capable of lifting the latch part 220 over the step 211 or other catching portion 211 of the support structure 210.
In particular, contracting the SMA wire 228a by a first amount leads to the latch part 220 falling off the first step 211 of the support structure 210. Contracting the SMA wire 228a further, by a second amount, leads to the latch part 220 falling off the second step 211′ of the support structure 210. The support structure 210 thus comprises two catching portions 211, 211′ that sequentially catch the latch part 220 in two different positions. The release part may be configured to either release the latch part 220 from both latched positions simultaneously (such that the latch part 220 is released directly to the unlatched position form either first and second latched position), or to release the latch part 220 sequentially from the second and first latched positions (such that contraction of the SMA wire 228a′ by a first amount releases the latch part 220 from the second latched position to the first latched position, and further contraction by a second amount released the latch part 220 from the first latched position to the unlatched position).
Although the latch assembly 200 of
The multi-stage latch 200 of
Furthermore, a spring mechanism 120c is selectively engageable with the movable part 102′. When the latch part 220 is disengaged (as shown), the second movable part 122 may move with the movable part 102′ such that no spring force is applied by the spring mechanism 120c. When the latch part 220 is engaged (not shown), then the second movable part 122 is constrained from moving relative to the base portion 10. A spring force is applied by resilient element 123 to the movable part 102′, thereby applying an additional spring force to the cables 30. The resilient element 123 may have a comparable or higher stiffness than the retraction mechanism 110.
It will be appreciated that the spring mechanism 120c of
The term ‘shape memory alloy (SMA) wire’ may refer to any element comprising SMA. The SMA wire may have any shape that is suitable for the purposes described herein. The SMA wire may be elongate and may have a round cross section or any other shape cross section. The cross section may vary along the length of the SMA wire. It is also possible that the length of the SMA wire (however defined) may be similar to one or more of its other dimensions. The SMA wire may be pliant or, in other words, flexible. In some examples, when connected in a straight line between two elements, the SMA wire can apply only a tensile force which urges the two elements together. In other examples, the SMA wire may be bent around an element and can apply a force to the element as the SMA wire tends to straighten under tension. The SMA wire may be beam-like or rigid and may be able to apply different (e.g. non-tensile) forces to elements. The SMA wire may or may not include material(s) and/or component(s) that are not SMA. For example, the SMA wire may comprise a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term ‘SMA wire’ may refer to any configuration of SMA wire acting as a single actuating element which, for example, can be individually controlled to produce a force on an element. For example, the SMA wire may comprise two or more portions of SMA wire that are arranged mechanically in parallel and/or in series. In some arrangements, the SMA wire may be part of a larger piece of SMA wire. Such a larger piece of SMA wire might comprise two or more parts that are individually controllable, thereby forming two or more SMA wires.
Whilst the embodiments above have described actuator assemblies which use SMA wires, the skilled person will appreciate that the features of the bearing arrangements and the flexures described can be readily used with other forms of actuator components. For example, each actuator component may be a voice coil motor (VCM) actuator, but other types of actuator are possible, for example a piezoelectric actuator, a radial motor or others.
Aspects of the present invention are set out in the following clauses:
| Number | Date | Country | Kind |
|---|---|---|---|
| 2105221.2 | Apr 2021 | GB | national |
| 2113969.6 | Sep 2021 | GB | national |
| 2115907.4 | Nov 2021 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2022/050944 | 4/13/2022 | WO |
