WO2020008216A1

WO2020008216A1 - Rolling pulleys

Info

Publication number: WO2020008216A1
Application number: PCT/GB2019/051920
Authority: WO
Inventors: James Howarth
Original assignee: Cambridge Mechatronics Limited
Priority date: 2018-07-06
Filing date: 2019-07-05
Publication date: 2020-01-09
Also published as: CN112654784A; GB2575318A; GB201811152D0

Abstract

Broadly speaking, embodiments of the present techniques provide techniques for increasing the stroke of an actuator comprising shape memory alloy (SMA) actuator wire.

Description

Rolling Pulleys

The present application generally relates to a shape memory alloy (SMA) actuator, and in particular to compact shape memory alloy actuators comprising at least one pulley that enables the actuator to deliver a relatively large output stroke.

In a first approach of the present techniques, there is provided an actuator comprising : a static component; a moveable component moveable relative to the static component; at least one pulley arranged to undergo rotational motion and translational motion and thereby drive movement of the moveable component; and at least one shape memory alloy (SMA) actuator wire coupled to the static component and to the at least one pulley, and arranged to drive the rotational and translational motion of the at least one pulley.

In a second approach of the present techniques, there is provided an actuator comprising: a static component; a moveable component moveable relative to the static component; a pulley arranged to undergo rotational motion and thereby drive rotational movement of the moveable component; a first shape memory alloy (SMA) actuator wire coupled at one end to the static component and at another end to the pulley, and arranged to drive the rotational motion of the pulley in a first direction; and a second SMA actuator wire coupled at one end to the static component and at another end to the pulley, and arranged to drive the rotational motion of the pulley in a second direction that is opposite to the first direction.

In a third approach of the present techniques, there is provided an actuator comprising : a static component; a moveable component moveable relative to the static component; a pulley arranged to undergo rotational motion and translational motion, provided in an abutting relationship between the static component and the moveable component and operatively arranged to roll along the static component and thereby drive translation movement of the moveable component; and a shape memory alloy (SMA) actuator wire coupled to the static component and to the pulley, and arranged to drive the rotational and translational motion of the pulley. In a fourth approach of the present techniques, there is provided an apparatus comprising: an actuator as described herein for moving a component of the apparatus, where the moveable component of the actuator is coupled to the component of the apparatus that is to be moved.

The apparatus may be any one of: a smartphone, a camera, a foldable smartphone, a foldable image capture device, a foldable smartphone camera, an image capture device, a servomotor, a consumer electronic device, a mobile computing device, a laptop, a tablet computing device, a security system, a gaming system, an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device, a drone (aerial, water, underwater, etc.), an aircraft, a spacecraft, a submersible vessel, a vehicle, and an autonomous vehicle. It will be understood that this is a non-exhaustive list of example apparatus.

Preferred features are set out in the appended dependent claims.

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

Figure 1 shows an actuator comprising two opposing shape memory alloy (SMA) actuator wires that are each coupled to a static component at one end and a moveable component at another end;

Figure 2 shows an actuator comprising two opposing SMA actuator wires and two rollable/moveable pulleys;

Figure 3 shows an actuator comprising an alternative arrangement of two opposing SMA actuator wires and two Tollable pulleys;

Figure 4A shows a perspective view of an example actuator comprising two opposing SMA actuator wires and a plurality of Tollable pulleys;

Figure 4B shows a plan view of the example actuator shown in Figure 4A; Figure 5A shows a side view of the example actuator shown in Figure 4A arranged for linear motion;

Figure 5B shows a side view of the example actuator shown in Figure 4A arranged for rotating motion;

Figures 6A and 6B show side views of example actuators comprising one SMA actuator wire and a Tollable pulley;

Figure 7A shows a further example actuator comprising one SMA actuator wire and a Tollable pulley;

Figure 7B shows a further example actuator comprising one SMA actuator and a Tollable pulley;

Figure 8 shows a sketch of an arrangement of pulleys with different inner diameters;

Figure 9 shows a further example actuator comprising two SMA actuator wires and two Tollable pulleys;

Figure 10 shows an example actuator comprising two SMA actuator wires and a Tollable pulley; and

Figures 11A to 11D show various techniques for providing SMA actuator wire around a Tollable pulley and how the Tollable pulley may roll .

Broadly speaking, embodiments of the present techniques provide techniques for increasing the stroke of an actuator comprising shape memory alloy (SMA) actuator wire. In some cases, the increased stroke may be achieved with only a relatively small increase in actuator footprint (e.g. actuator size or cost). An SMA actuator having higher stroke may enable SMA actuators to be used for a wider range of applications, such as telephoto camera auto-focus and optical image stabilisation (OIS), shutter actuators (i.e. actuators which control camera aperture size), servo motors, and folding/foldable cameras. It will be understood that this is a non-exhaustive list of potential applications.

Figure 1 shows a schematic of an actuator 100 comprising two opposing shape memory alloy (SMA) actuator wires 102, 104 that are each coupled to a static component at one end and a moveable component 106 at another end. The actuator comprises a first SMA actuator wire 102 that is coupled at one end to the moveable component 106 and to a static component at another end via a crimp 108. The actuator also comprises a second SMA actuator wire 104 that is coupled at one end to the moveable component 106 and to the static component at another end via a crimp 110. When the first SMA actuator wire 102 is driven (i.e. powered), the wire heats and contracts, causing the moveable component 106 to move in a first direction. This causes the second SMA actuator wire 104 to stretch. When the first SMA actuator wire 102 is no longer being driven, the moveable component 106 may stay in position (or may not significantly move from the position it reached when the first SMA actuator wire 102 was being driven). When the second SMA actuator wire 104 is driven (i.e. powered), the wire heats and contracts, causing the moveable component 106 to move in a second direction (which is opposite to the first direction) This causes the first SMA actuator wire to stretch. Thus, the moveable component 106 may be moved linearly, as indicated by arrow A.

A limitation of SMA materials is the amount of stroke they are able to provide - typically, an SMA material experiences a 4% contraction when it is repeatedly heated past the transition temperature. Accordingly, one approach to achieve a larger displacement (e.g. of a moveable component of an actuator), is to increase the length of the SMA actuator wire. However, if in Figure 1 the length of SMA actuator wires 102, 104 was increased, the overall size of the actuator 100 would increase, which may be undesirable as the actuator 100 may need to be incorporated into a device having a particular size. Another approach to address the problem of stroke is to use angled wires to amplify stroke. However, this may result in a larger actuator footprint (e.g. larger size) in order to accommodate the angled wire arrangement in the actuator. A further approach to address the problem of stroke is to wrap SMA wire around a pulley or pulley wheel to increase the stroke without a significant increase in the footprint (e.g. size) of the actuator. However, this results in mechanical losses due to friction at the pulley axle.

The present techniques, described below with reference to Figures 2 to 11D, provide solutions to the above-described problems.

Broadly speaking, the present techniques provide an actuator comprising: a static component; a moveable component moveable relative to the static component; at least one pulley arranged to undergo rotational motion and translational motion and thereby drive movement of the moveable component; and at least one shape memory alloy (SMA) actuator wire coupled to the static component and to the at least one pulley, and arranged to drive the rotational and translational motion of the at least one pulley.

The at least one pulley may be arranged to drive translational motion and/or rotational motion of the moveable component.

In embodiments, in addition to the rotational motion, the at least one pulley may undergo translational motion.

The at least one pulley may roll along a surface. In embodiments, the pulley may be arranged such that a circumferential edge of the at least one pulley may roll along the surface. Alternatively, the pulley may be arranged such that an axle of the at least one pulley may roll along the surface. In any case, the surface may be substantially flat or may be curved.

The at least one SMA actuator wire may be coupled to an axle of the at least one pulley. Alternatively, the at least one SMA actuator wire may be provided around at least part of a circumferential edge of the at least one pulley.

In embodiments, an axle of the at least one pulley may be fixedly attached to a surface, and the at least one pulley rotates about its axle. In this case, the at least one pulley is not able to undergo translational motion. In embodiments, the actuator may further comprise a resilient biasing member to oppose the driving of the moveable component by the at least one pulley. Alternatively, the at least one pulley may drive the moveable component when the at least one SMA actuator wire is heated, and cooling of the SMA actuator wire drives movement of the moveable component in an opposite direction, such that a resilient biasing member is not required.

In embodiments, the actuator may comprise two pulleys, or a plurality of pulleys. The pulleys may be different sizes. For example, a diameter of the pulleys may be different, and/or the diameter or height of the axle of the pulleys may be different.

The actuator may comprise two SMA actuator wires, or two lengths of SMA actuator wire. The two SMA actuator wires (or lengths of SMA actuator wire) may be opposing wires, such that a first SMA actuator wire (or length) is arranged to drive the rotational motion of the at least one pulley in a first direction, and a second SMA actuator wire (or length) is arranged to drive the rotational motion of the at least one pulley in a second direction that is opposite to the first direction.

Figure 2 shows an actuator 200 comprising two opposing SMA actuator wires and two rollable/moveable pulleys. The actuator 200 comprises a first SMA actuator wire 202 that is coupled at one end to a moveable component 206 and to a static component at another end via a crimp 208. The actuator 200 also comprises a second SMA actuator wire 204 that is coupled at one end to the moveable component 206 and to the static component at another end via a crimp 210. When the first SMA actuator wire 202 is driven (i.e. powered), the wire heats and contracts, causing the moveable component 206 to move in a first direction. This causes the second SMA actuator wire 204 to stretch or expand. When the first SMA actuator wire 202 is no longer being driven, the moveable component 206 may stay in position (or may not significantly move from the position it reached when the first SMA actuator wire 202 was being driven). Similarly, when the second SMA actuator wire 204 is driven (i.e. powered), the wire heats and contracts, causing the moveable component 206 to move in a second direction (which is opposite to the first direction). This causes the first SMA actuator wire to stretch. When the second SMA actuator wire 204 is no longer being driven, the moveable component 206 may stay in position (or may not significantly move from the position it reached when the second SMA actuator wire 204 was being driven). Thus, the moveable component 206 may be moved linearly, as indicated by arrow B.

The first SMA actuator wire 202 is provided around a pulley or pulley wheel 212, such that a first length li of the first SMA actuator wire 202 is provided between crimp 208 and pulley 212, and a second length I2 of the first SMA actuator wire 202 is provided between pulley 212 and the moveable component 206. Accordingly, the two lengths or segments of the first SMA actuator wire 202 may be considered to be parallel or substantially parallel. Pulley 212 may be able to roll on surface 216. In other words, the position of pulley 212 is not fixed relative to the surface 216, and the pulley 212 may be able to roll along surface 216 in the direction indicated by arrow C. Surface 216 may be any hard surface. Surface 216 may be a substantially flat surface or may be a curved surface. The pulley 212 may be held in position on surface 216 by the force exerted by wire 202 on the pulley 212 when the wire is under tension. (The amount of tension may vary between different actuator arrangements and/or depending on the specific application the actuator is being used for). When the first SMA actuator wire 202 contracts, the wire contracts around pulley 212 such that the moveable component 206 moves in the first direction towards pulley 212. The movement of the first SMA actuator wire 202 around the pulley 212 exerts a force on the pulley 212 that may cause the pulley 212 to roll on surface 216. When the first SMA actuator wire 202 contracts, the pulley 212 may roll in one direction (e.g. towards the left-hand side in Figure 2). When the first SMA actuator wire 202 stops being driven, the pulley 212 may roll in the opposite direction (e.g. towards the right-hand side of Figure 2). Thus, by enabling the pulley 212 to roll along surface 216, mechanical losses due to friction may be reduced.

Similarly, a length of the second SMA actuator wire 204 is provided around a pulley or pulley wheel 214. The two lengths or segments of the second SMA actuator wire 204 around the pulley 214 may be considered to be parallel or substantially parallel. Pulley 214 may be able to roll on surface 218. In other words, the position of pulley 212 is not fixed relative to the surface 218, and the pulley 214 may be able to roll along surface 218 in the direction indicated by arrow D. Surface 218 may be any hard surface. Surfaces 216 and 218 may be made of the same material or different materials. Surfaces 216 and 218 may be different surfaces of the actuator 200. The pulley 214 may be held in position on surface 218 by the force exerted by wire 204 on the pulley 214 when the wire is under tension. When the second SMA actuator wire 204 contracts, the wire contracts around pulley 214 such that the moveable component 206 moves in the second direction towards pulley 218. The movement of the second SMA actuator wire 204 around the pulley 214 exerts a force on the pulley 214 that may cause the pulley 214 to roll on surface 218. When the second SMA actuator wire 204 contracts, the pulley 214 may roll in one direction (e.g. towards the right-hand side in Figure 2). When the second SMA actuator wire 204 stops being driven, the pulley 214 may roll in the opposite direction (e.g. towards the left-hand side of Figure 2). Thus, by enabling the pulley 214 to roll along surface 218, mechanical losses due to friction may be reduced or avoided.

It can be seen from Figure 2 that the length of the first and second SMA actuator wires 202, 204 may be increased relative to the length of the first and second SMA actuator wires 102, 104 in Figure 1, without substantially impacting the footprint of the actuator (i.e. without substantially increasing a length of the actuator). Thus, the arrangement shown in Figure 2 may advantageously increase the length of the SMA actuator wire (and therefore the stroke of the actuator 200), without substantially increasing the size of the actuator and while also reducing mechanical/frictional losses. In some cases, the frictional losses of the rolling pulley arrangement of Figure 2 may be up to 100 times smaller than the frictional losses that occur when a pulley is fixed and only able to rotate about a fixed axle.

In the arrangement shown in Figure 2, the SMA actuator wires are wrapped around their respective pulleys in such a way that segments li and I2 of each actuator wire are substantially parallel. Furthermore, each SMA actuator wire is coupled to a different surface. Specifically, the actuator 200 comprises two surfaces that are opposite each other or facing each other.

Figure 3 shows an actuator 300 comprising an alternative arrangement of two opposing SMA actuator wires and two Tollable pulleys. In Figure 3, segments h and li of each actuator wire are not parallel, and instead may be angled relative to each other. For example, the segments li and b may be perpendicular or substantially perpendicular to each other, as illustrated in Figure 3. In other words, each SMA actuator 302, 304 is coupled to the same surface, or to two different surfaces that are provided side-by-side. If the length of the SMA actuator wires are the same in Figures 2 and 3, the actuator arrangement shown in Figure 3 is wider than the arrangement shown in Figure 2. Thus, the arrangement of pulleys and wires may be selected to suit the dimensions of an apparatus into which the actuator may be incorporated.

The actuator 300 comprises a first SMA actuator wire 302 that is coupled at one end to a moveable component 306 and to a static component at another end via a crimp 308. The actuator 300 also comprises a second SMA actuator wire 304 that is coupled at one end to the moveable component 306 and to the static component at another end via a crimp 310. When the first SMA actuator wire 302 is driven (i.e. powered), the wire heats and contracts, causing the moveable component 306 to move in a first direction. This causes the second SMA actuator wire 304 to stretch or expand. When the first SMA actuator wire 302 is no longer being driven, the moveable component 306 may stay in position (or may not significantly move from the position it reached when the first SMA actuator wire 302 was being driven). Similarly, when the second SMA actuator wire 304 is driven (i.e. powered), the wire heats and contracts, causing the moveable component 306 to move in a second direction (which is opposite to the first direction). This causes the first SMA actuator wire to stretch. When the second SMA actuator wire 304 is no longer being driven, moveable component 306 may stay in position (or may not significantly move from the position it reached when the second SMA actuator wire 304 was being driven). Thus, the moveable component 306 may be moved linearly, as indicated by arrow E.

A length of the first SMA actuator wire 302 is provided around a pulley or pulley wheel 312. Pulley 312 may be able to roll on surface 316. In other words, the position of pulley 312 is not fixed relative to the surface 316, and the pulley 312 may be able to roll along surface 316. Surface 316 may be any hard surface. The pulley 312 may be held in position on surface 316 by the force exerted by wire 302 on the pulley 312 when the wire is under tension. When the first SMA actuator wire 302 contracts, the wire contracts around pulley 312 such that the moveable component 306 moves in the first direction towards pulley 312. The movement of the first SMA actuator wire 302 around the pulley 312 exerts a force on the pulley 312 that may cause the pulley 312 to roll on surface 316. When the first SMA actuator wire 302 contracts, the pulley 212 may roll in one direction, and when the first SMA actuator wire 302 stops being driven, the pulley 312 may roll in the opposite direction. Thus, by enabling the pulley 312 to roll along surface 316, mechanical losses due to friction may be reduced or avoided.

Similarly, a length of the second SMA actuator wire 304 is provided around a pulley or pulley wheel 314. Pulley 314 may be able to roll on surface 318. In other words, the position of pulley 314 is not fixed relative to the surface 318, and the pulley 314 may be able to roll along surface 318. Surface 318 may be any hard surface. Surfaces 316 and 318 may be made of the same material or different materials. Surfaces 316 and 318 may be different surfaces of the actuator 300. The pulley 314 may be held in position on surface 318 by the force exerted by wire 304 on the pulley 314 when the wire is under tension. When the second SMA actuator wire 304 contracts, the wire contracts around pulley 314 such that the moveable component 306 moves in the second direction towards pulley 318. The movement of the second SMA actuator wire 304 around the pulley 314 exerts a force on the pulley 314 that may cause the pulley 314 to roll on surface 318. When the second SMA actuator wire 304 contracts, the pulley 314 may roll in one direction, and when the second SMA actuator wire 304 stops being driven, the pulley 314 may roll in the opposite direction. Thus, by enabling the pulley 314 to roll along surface 318, mechanical losses due to friction may be reduced or avoided.

It can be seen from Figure 3 that the length of the first and second SMA actuator wires 302, 304 may be increased relative to the length of the first and second SMA actuator wires 102, 104 in Figure 1, without substantially impacting the footprint of the actuator (i.e. without substantially increasing a length of the actuator). Thus, the arrangement shown in Figure 3 may advantageously increase the length of the SMA actuator wire (and therefore the stroke of the actuator 300), without substantially increasing the size of the actuator and while also reducing mechanical/frictional losses. The pulleys may be different sizes. For example, a diameter of the pulleys may be different, and/or the diameter or height of the axle of the pulleys may be different. The angle Q that each surface 316, 318 makes relative to some reference line (e.g. relative to an edge or line of the static component along which the SMA actuator wires 302, 304 are coupled) may be the same or may be different.

Figure 9 shows a further example actuator 900 comprising two SMA actuator wires and two Tollable pulleys. The actuator 900 comprises a first SMA actuator wire 902 that is coupled at one end to a moveable component 906 and to a static component at another end via a crimp 908. The first SMA actuator wire 902 is provided around (e.g. looped around) a first pulley or pulley wheel 912. The first pulley 912 is arranged to roll on first surface 920. The first SMA actuator wire 902 is provided around an axle 914 of the first pulley 912. When the first SMA actuator wire 902 is driven (i.e. powered), the wire heats and contracts. The contraction of the first SMA actuator wire 902 causes a force to be exerted on pulley 912, which in turn causes pulley 912 to roll along surface 920 in one direction. As the pulley 912 rolls, the moveable component 906 may be moved in a first direction (e.g. towards the left-hand side in Figure 9).

The actuator 900 also comprises a second SMA actuator wire 904 that is coupled at one end to the moveable component 906 and to the static component at another end via a crimp 910. The second SMA actuator wire 904 is provided around (e.g. looped around) a second pulley or pulley wheel 916. The second pulley 916 is arranged to roll on first surface 922. The second SMA actuator wire 904 is provided around an axle 918 of the second pulley 916. When the second SMA actuator wire 904 is driven (i.e. powered), the wire heats and contracts. The contraction of the second SMA actuator wire 904 causes a force to be exerted on pulley 916, which in turn causes pulley 916 to roll along surface 922 in one direction. As the pulley 916 rolls, the moveable component 906 may be moved in a second direction (e.g. towards the right-hand side in Figure 9).

The arrangement of Figure 9 is similar to the arrangement shown in Figure 2, except that the lengths or segments of each SMA actuator wire around each pulley are not parallel. The V-shape of each SMA actuator wire may result in the moveable component 906 being pulled both by the contraction of a wire and by the rolling of a pulley. In either case, by enabling the pulleys 912, 916 to roll along their respective surfaces 920, 922, mechanical losses due to friction may be reduced.

It can be seen from Figure 9 that the length of the first and second SMA actuator wires 902, 904 may be increased relative to the length of the first and second SMA actuator wires 102, 104 in Figure 1, without substantially impacting the footprint of the actuator (i.e. without substantially increasing a length of the actuator). Thus, the arrangement shown in Figure 9 may advantageously increase the length of the SMA actuator wire (and therefore the stroke of the actuator 900), without substantially increasing the size of the actuator and while also reducing mechanical/frictional losses.

Accordingly, in embodiments, the actuator may comprise a first SMA actuator wire and a second SMA actuator wire, and a first pulley and a second pulley.

In embodiments, the first SMA actuator wire may be coupled at a first end to the static component and at a second end to the moveable component, and a portion of the first SMA actuator wire may be provided around the first pulley; and the second SMA actuator wire may be coupled at a first end to the static component and at a second end to the moveable component, and a portion of the second SMA actuator wire may be provided around the second pulley, wherein the moveable component may be provided between the first and second pulley.

In embodiments, the first end of the first SMA actuator wire may be coupled to a first side of the static component; and the first end of the second SMA actuator wire may be coupled to a second side of the static component, where the second side of the static component is opposite the first side.

The first pulley may be in close proximity to the second side of the static component; and the second pulley may be in close proximity to the first side of the static component.

In embodiments, the actuator may comprise: a first surface upon which the first pulley is arranged to undergo rotational motion and translational motion; and a second surface upon which the second pulley is arranged to undergo rotational and translational motion.

The first surface and second surface may be substantially parallel to the first side and second side of the static component.

In embodiments, a length of the first SMA actuator wire may be substantially perpendicular to the first surface, and a length of the second SMA actuator wire may be substantially perpendicular to the second surface. (The lengths of SMA actuator wire may not need to be exactly perpendicular relative to the surfaces). Alternatively, a length of the first SMA actuator wire may form a first acute angle (<90°) with the first surface, and a length of the second SMA actuator wire may form a second acute angle (<90°) with the second surface. The first acute angle and the second acute angle may be equal or different.

In embodiments, the first end of the first SMA actuator wire and the first end of the second SMA actuator wire may both be coupled to a side of the static component. The first pulley and the second pulley may be provided at a distance from the side of the static component. The actuator may further comprise: a first surface upon which the first pulley is arranged to undergo rotational motion and translational motion; and a second surface upon which the second pulley is arranged to undergo rotational and translational motion. The first surface may form a first angle relative to the side of the static component, and the second surface may form a second angle relative to the side of the static component. The first angle and the second angle may be equal or different.

Figure 4A shows a perspective view of an example actuator 400 comprising two opposing SMA actuator wires and a plurality of Tollable pulleys, and Figure 4B shows a plan view of the example actuator shown in Figure 4A. For the sake of simplicity, only one of the SMA actuator wires is shown in Figures 4A and 4B.

The actuator 400 comprises a static component 420 and a moveable component 406. The static component 420 comprises a slot or hole 418, and the moveable component 406 is arranged to move or slide within the hole 418. The moveable component 406 may comprise two legs 426 which extend into the hole 418 and are arranged to engage with opposite sides of the hole 418. Each leg 426 comprises a foot 428 which is arranged to engage with an underside of static component 420 through the hole 418 and secure the moveable component 406 to hole 418.

The actuator comprises a first SMA actuator wire 402 that is coupled at one end to the moveable component 406 via crimp 412, and to the static component 420 at another end via crimp 408. The actuator 400 also comprises a second SMA actuator wire (not shown in Figures 4A and 4B) that is also coupled at one end to the moveable component 406 via a crimp, and to the static component 420 at another end via crimp 410. The static component 420 comprises an electrical terminal 422, which may be located close to an edge of hole 418. An electrical connector 424 electrically couples together crimp 412 and electrical terminal 422. The electrical connector 424 may have a concertina, coil or spring-like shape that enables the electrical connector 424 to stretch and contract as the moveable component 406 moves. As a result, the moveable component 406 is able to move in hole 418 while maintaining an electrical connection between the crimp 412 and terminal 422. The electrical terminal 422 may be coupled to a power supply (not shown), which may be used to selectively drive the SMA actuator wires of actuator 400. In embodiments, each of the two SMA actuator wires of actuator 400 may be coupled to a separate crimp on the moveable component 406, where each crimp is coupled to a separate electrical terminal on the static component 420. In this case, the end of each SMA actuator wire which is coupled to the moveable component 406 may be independently coupled to a power supply. Alternatively, each of the two SMA actuator wires of actuator 400 may be coupled to the same crimp 412 of the moveable component 406. In this case, the end of each SMA actuator wire which is coupled to the moveable component 406 may be coupled to the power supply via the same terminal 422.

The actuator 400 comprises a plurality of Tollable pulleys. In the embodiment depicted in Figure 4A, the actuator has twelve Tollable pulleys (six for each SMA actuator wire), but it will be understood that this is merely one non- limiting arrangement. More generally, the actuator 400 may comprise two or more Tollable pulleys, i .e. such that each SMA actuator wire is provided around one or more Tollable pulleys. In the embodiment shown in Figure 4A, the first SMA actuator wire 402 is provided around (e.g. wound partly around) six Tollable pulleys - a first set of Tollable pulleys 414a are provided on a first side of the static component 420, and a second set of Tollable pulleys 414b are provided on a second side of the static component 420 (where the first side is opposite to the second side). In the depicted arrangement, the first set of Tollable pulleys 414a comprises three pulleys, and the second set of Tollable pulleys 414b also comprises three pulleys. SMA actuator wire 402 is crimped at one end in crimp 408 and is wound around a pulley of the first set of Tollable pulleys 414a followed by a pulley of the second set of Tollable pulleys 414b in an alternating manner. Once the first SMA actuator wire 402 has been wound around all of the pulleys in the first and second sets of Tollable pulleys 414a, 414b, the free end (i.e. the uncrimped end) of the first SMA actuator wire 402 is coupled to crimp 412 on the moveable component 406.

Similarly, the second SMA actuator wire (not shown) is provided around (e.g. wound partly around) six Tollable pulleys - a first set of Tollable pulleys 416a are provided on the first side of the static component 420, and a second set of Tollable pulleys 416b are provided on the second side of the static component. In the depicted arrangement, the first set of Tollable pulleys 416a comprises three pulleys, and the second set of Tollable pulleys 416b also comprises three pulleys. The second set of Tollable pulleys 416b also comprises three pulleys. The second SMA actuator wire is crimped at one end in crimp 410 and is wound around a pulley of the second set of Tollable pulleys 416b followed by a pulley of the first set of Tollable pulleys 416a in an alternating manner. Once the second SMA actuator wire has been wound around all of the pulleys in the first and second sets of Tollable pulleys 416a, 416b, the free end (i.e. the uncrimped end) of the second SMA actuator wire is coupled to crimp 412 on the moveable component 406.

When the first SMA actuator wire 402 is driven (i.e. powered), the wire heats up and contracts around each of the pulleys in the first and second set of Tollable pulleys 414a, 414b. The contraction of the first SMA actuator wire 402 causes the moveable component 406 to move in a first direction. In this case, the moveable component 406 moves in slot 418 in a direction towards crimp 408. This movement of moveable component 406 causes the second SMA actuator wire to stretch or expand. When the first SMA actuator wire 402 is no longer being driven, the moveable component 406 may stay in position (or may not significantly move from the position it reached when the first SMA actuator wire 402 was being driven). Similarly, when the second SMA actuator wire (not shown) is driven (i.e. powered), the wire heats and contracts, causing the moveable component 406 to move in a second direction (which is opposite to the first direction). In this case, the moveable component 406 moves in slot 418 in a direction towards crimp 410. This movement causes the first SMA actuator wire 402 to stretch. When the second SMA actuator wire is no longer being driven, the moveable component 406 may stay in position (or may not significantly move from the position it reached when the second SMA actuator wire 404 was being driven). Thus, the moveable component 406 may be moved linearly within slot 418 of static component 420.

Each Tollable pulley of actuator 400 is not fixed to the static component 420. Instead, each Tollable pulley is provided in a slot 430 of the static component 420 and is held in position in the slot 430 by the force exerted by the SMA actuator wire that is wound around the pulley (as the wire is under tension). When one of the SMA actuator wires contracts, the wire contracts around a pulley and exerts a force on the pulley that may cause the pulley to move within its slot 430. (A cover (not shown) may be provided over the at least the slots 430 at each end of the static component, to prevent the Tollable pulleys from rolling/moving out of the slots.) Thus, by enabling the pulleys to move freely with their slots 430, mechanical losses due to friction may be reduced.

It can be seen from Figure 4A that the length of the first and second SMA actuator wires may be increased relative to the length of the first and second SMA actuator wires 102, 104 in Figure 1, without substantially impacting the footprint of the actuator (i.e. without substantially increasing a length of the actuator). The length of each SMA actuator wire may be altered by altering the number of pulleys around which the SMA actuator wire is wrapped. Thus, the arrangement shown in Figure 4A may advantageously increase the length of the SMA actuator wire (and therefore the stroke of the actuator 400), without substantially increasing the length of the actuator and while also reducing mechanical/frictional losses. Figure 5A shows a side view of the example actuator 400 shown in Figure 4A, where the actuator is configured for linear motion. Here, the moveable component 406 is coupled to a sliding element 500 which is able to move linearly (i.e. side-to-side) when moveable component 406 moves linearly in slot 418. The sliding element 500 may comprise a coupling feature 512, which enables the sliding element 500 to be coupled to any other component which is required to move in a linear manner.

Figure 5B shows a side view of the example actuator 400 shown in Figure 4A, where the actuator is configured for rotational motion. Here, the moveable component 406 is coupled to a sliding element 502 which is able to move linearly when moveable component 406 moves linearly in slot 418. The sliding element 502 is configured to convert linear motion into rotational motion. The sliding element 502 comprises a series of teeth 504. In this embodiment, the actuator 400 comprises a gear 506, where the gear 506 comprises a series of teeth that correspond to the teeth 504 of the sliding element 502. The gear 506 is arranged such that the teeth of gear 506 engage with teeth 504 of the sliding element. Thus, when the sliding element 502 moves side-to-side, the linear motion is converted into rotational motion by the interaction between the gear 506 and the teeth 504. The gear 506 may comprise or be coupled to a pin 508 which rotates as the gear 506 rotates. The pin 508 may be coupled to any other component which is required to rotate. Thus, the actuator 400 may be used to control the rotational motion of a component.

As mentioned earlier, at least the slots 430 and pulleys may be encased or covered to prevent the pulleys from rolling out of the slots. As shown in Figures 5A and 5B, the actuator 400 may be at least partly encased within a cover or housing 510. The cover 510 may be shaped to encase some components of the actuator 400 (such as the actuator wires and the rolling pulleys), while allowing other components to protrude from/extend through the cover (such as the sliding element 502, the coupling feature 512 and the pin 508).

Thus, in embodiments, the actuator may comprise a first length of SMA actuator wire and a second length of SMA actuator wire, and at least two pulleys. Alternatively, the actuator may comprise a first length of SMA actuator wire and a spring or other resilient element in place of the second length of SMA actuator wire.

The static component may comprise a first side and a second side, and the moveable component is arranged on a surface of the static component between the first and second sides of the static component.

The first length of SMA actuator wire may be coupled at a first end to the first side of the static component, and at a second end to the moveable component; and the second length of SMA actuator wire may be coupled at a first end to the second side of the static component, and at a second end to the moveable component.

At least one pulley may be provided at the second end of the static component, and a portion of the first length of SMA actuator wire is provided around the at least one pulley at the second end; and at least one pulley is provided at the first end of the static component, and a portion of the second length of SMA actuator wire is provided around the at least one pulley at the first end.

In embodiments, the actuator may comprise a first set of pulleys, a second set of pulleys, a third set of pulleys and a fourth set of pulleys, each of which may comprise at least one pulley. The first set of pulleys may be provided at the second end of the static component, the second set of pulleys may be provided at the first end of the static component, and the first length of SMA actuator wire may be wound around a pulley of the first set of pulleys and a pulley of the second set of pulleys in an alternating manner; and the third set of pulleys may be provided at the first end of the static component, the fourth set of pulleys may be provided at the second end of the static component, and the second length of SMA actuator wire may be wound around a pulley of the third set of pulleys and a pulley of the fourth set of pulleys in an alternating manner.

Each pulley may be provided in an individual slot in the static component. An electrical terminal may be provided on the surface of the static component on which the moveable component is arranged. An expandable electrical connector may be provided to couple the moveable component to the electrical terminal.

The actuator may comprise a sliding element coupled to the moveable component and arranged to undergo translational motion. The sliding element may be arranged to convert translational motion into rotational motion.

The first length of SMA actuator wire and second length of SMA actuator wire may be portions of a single SMA actuator wire. In this case, the first length and second length may be separately driveable/powered. Alternatively, the first length of SMA actuator wire may be provided by a first SMA actuator wire, and the second length of SMA actuator wire may be provided by a second SMA actuator wire.

Figure 6A shows a side view of another example actuator 600 comprising one SMA actuator wire 602 and a Tollable pulley 604. The SMA actuator wire 602 is wound or wrapped around an axle 606 of Tollable pulley 604. The Tollable pulley 604 comprises a series of teeth along a circumferential edge of the Tollable pulley 604. That is, Tollable pulley 604 may take the form of a gear or cogwheel. The actuator 600 may comprise a static component 612. The static component 612 may comprise a surface bearing a series of teeth which correspond to, and engage with, the teeth of Tollable pulley 604. Each end of the SMA actuator wire 602 may be coupled to a crimp 608, 610. Crimp 608 may be provided on the static component 612 or elsewhere. The actuator 600 may comprise a moveable component 614. The moveable component 614 may comprise a surface bearing a series of teeth which correspond to, and engage with, the teeth of Tollable pulley 604.

When the SMA actuator wire 602 is driven (i.e. powered), the wire heats up and contracts. The contraction of the wire around axle 606 may cause the axle, and therefore the pulley 604, to rotate in one direction (e.g. clockwise or anti- clockwise). As the Tollable pulley 604 rotates, the engagement of the teeth of the Tollable pulley 604 and the teeth of static component 612 cause the Tollable pulley 604 to move along the static component 612. As the Tollable pulley 604 moves, the moveable component 614 also moves because the teeth of the moveable component 614 are engaged with the teeth of the Tollable pulley 604. Thus, the actuator 600 may be used to convert rotational motion into linear motion. When the SMA actuator wire 602 is no longer being driven, the wire may expand and this may cause the Tollable pulley 604 to rotate in the opposite direction (e.g. anti- clockwise or clockwise). Accordingly, the moveable component 614 may be caused to move in the opposite direction.

Figure 6A shows the Tollable pulley 604 as having teeth which correspond to teeth of the static and moveable components. However, in alternative embodiments, none of these components may have teeth . Instead, the actuator may use friction to cause movement of the moveable component 614. In this case, the Tollable pulley 604 may be held relatively firmly between the static component 612 and the moveable component 614. The surfaces which are in contact in this case may be rough or roughened to increase the friction between the various elements of the actuation 600. As the Tollable pulley 604 rotates, the friction between the Tollable pulley 604 and the static component 612 may be sufficient to cause the Tollable pulley 604 to move along the static component. As the Tollable pulley 604 moves, the frictional forces between the Tollable pulley 604 and moveable component 614 may be great enough to cause the moveable component 614 to also move.

Figure 6B shows a side view of another example actuator 600' comprising one SMA actuator wire 602' and a Tollable pulley 604'. The SMA actuator wire 602' is wound or wrapped around an axle 606' of Tollable pulley 604'. The actuator 600' may comprise a static component 612'. Each end of the SMA actuator wire 602' may be coupled to a crimp 608', 610'. Crimp 608' may be provided on the static component 612' or elsewhere. The actuator 600' may comprise a moveable component 614'. The actuator 600' may comprise one or more straps or bands which help the Tollable pulley 604' to move with respect to the static component 612' and thereby cause movement of the moveable component 614'. In the depicted arrangement, the actuator 600' comprises four straps 618a' to 618d'. Each strap may be coupled at one end to the static component 612' or the moveable component 614' via a coupling means 616', and may be coupled at another end to the Tollable pulley 604' via a coupling means 620'. In the specific arrangement shown in Figure 6B, strap 618a' is coupled at one end to static component 612' via coupling means 616a', and at another end to Tollable pulley 604' via coupling means 620b'. Strap 618b' is coupled at one end to moveable component 614' via coupling means 616b', and at another end to Tollable pulley 604' via coupling means 620b'. Strap 618c' is coupled at one end to static component 612' via coupling means 616c', and at another end to Tollable pulley 604' via coupling means 620a'. Strap 618d' is coupled at one end to moveable component 614' via coupling means 616d', and at another end to Tollable pulley 604' via coupling means 620a'. Each strap 618a' to 618d' may be formed of a non-elastic material.

When the SMA actuator wire 602' is driven (i.e. powered), the wire heats up and contracts. The contraction of the wire around axle 606' may cause the axle, and therefore the pulley 604', to rotate in one direction (e.g. clockwise or anti-clockwise). As the Tollable pulley 604' rotates, the arrangement of the straps 618a' to 618d' may cause the Tollable pulley 604' to move along the static component 612' in one direction. As the Tollable pulley 604' moves, the moveable component 614' also moves because of the arrangement of the straps. Thus, the actuator 600' may be used to convert rotational motion into linear motion. When the SMA actuator wire 602' is no longer being driven, the wire may expand and this may cause the Tollable pulley 604' to rotate in the opposite direction (e.g. anti-clockwise or clockwise). Accordingly, the moveable component 614' may be caused to move in the opposite direction.

As the Tollable pulley 604 is free to move between the static component 612 and the moveable component 614, the Tollable pulley 604 is not fixed. As a result, mechanical losses due to friction may be reduced.

In embodiments, the actuator may comprise one SMA actuator wire and one pulley.

The pulley may be arranged to undergo rotational motion and translational motion. The pulley may be provided in an abutting relationship between the static component and the moveable component and operatively arranged to roll along the static component and thereby drive translational movement of the moveable component. The SMA actuator wire may be coupled to the static component and to the pulley, and arranged to drive the rotational and translational motion of the pulley.

The pulley may comprise a plurality of teeth along a circumferential edge of the pulley; the static component may comprise a surface bearing a series of teeth that engage with the teeth of the pulley; and the moveable component may comprise a surface bearing a series of teeth that engage with the teeth of the pulley. Alternatively, the actuator may comprise at least two straps, where a first strap is coupled at one end to the static component and at another end to the pulley, and a second strap is coupled at one end to the moveable component and at another end to the pulley. In any case, the SMA actuator wire may be coupled at a first end to the static component and may be wrapped around an axle of the pulley.

The pulley may be arranged to convert rotational motion into translational motion.

Figure 7A shows a further example actuator 700 comprising one SMA actuator wire 702 and a Tollable pulley 708. The SMA actuator wire 702 may be coupled to a moveable component 706 at one end and to a static component 704 at another end. The SMA actuator wire 702 is provided around Tollable pulley 708. The Tollable pulley 708 may be arranged to roll/move along a surface 710. When the SMA actuator wire 702 is driven (i .e. powered), the wire heats up and contracts. The contraction of the SMA actuator wire 702 causes the moveable component 706 to move in the direction of the arrow. The Tollable pulley 708 of actuator 700 is not fixed in position relative to surface 710. Instead, the Tollable pulley 708 is held in position on/against surface 710 by the force exerted by SMA actuator wire 702 that is wound around the pulley (as the wire is under tension) . When the SMA actuator wire 702 contracts, the wire contracts around the Tollable pulley 708 and exerts a force on the pulley that may cause the pulley to move/roll along surface 710. (Barriers or endstops or similar elements may be provided on surface 710 to restrict the rolling motion of the Tollable pulley 708.) Thus, by enabling the Tollable pulley 708 to move/roll along surface 710, mechanical losses due to friction may be reduced. Furthermore, relative to the arrangement shown in Figure 1, this arrangement may enable a longer length of SMA actuator wire to be provided (and therefore, a larger actuator stroke to be achieved), without substantially impacting the footprint of the actuator.

Figure 7B shows a further example actuator 750 comprising one SMA actuator wire 752 and a pulley 758. The SMA actuator wire 752 may be coupled to a moveable component 756 at one end and to a static component 754 at another end. The SMA actuator wire 752 is provided around pulley 758. The pulley 758 may be a Tollable pulley arranged to either roll/move along a surface, or may be a static pulley fixed to a surface and able to rotate (but not roll/move). In the former case, the Tollable pulley 758 may be held in position on/against the surface by the force exerted by SMA actuator wire 752 that is wound around the pulley (as the wire is under tension). In either case, when the SMA actuator wire 752 is driven (i.e. powered), the wire heats up and contracts. The contraction of the SMA actuator wire 752 causes the moveable component 756 to move in the direction of the arrow. When the SMA actuator wire 752 contracts, the wire contracts around the pulley 758 and exerts a force on the pulley that may cause the pulley to either move/roll along the surface, or rotate, depending on the specific configuration. (Barriers or endstops or similar elements may be provided on the rolling surface to restrict the rolling motion of the Tollable pulley.) If the pulley 758 is a Tollable pulley, mechanical losses due to friction may be reduced or avoided. Whether or not the pulley 758 is a rolling pulley or static pulley, relative to the arrangement shown in Figure 1, the arrangement of Figure 7B may enable a longer length of SMA actuator wire to be provided (and therefore, a larger actuator stroke to be achieved), without substantially impacting the footprint of the actuator.

In embodiments, the actuator may comprise one SMA actuator wire and one pulley.

The SMA actuator wire may be coupled at a first end to the static component and at a second end to the moveable component, where a portion of the SMA actuator wire may be provided around the pulley. The actuator may comprise a surface upon which the pulley is arranged to undergo rotational motion and translational motion.

A first length of the SMA actuator wire between the static component and the pulley may be substantially parallel to a second length of the SMA actuator wire between the pulley and the moveable component. Alternatively, a first length of the SMA actuator wire between the static component and the pulley may be substantially non-parallel to a second length of the SMA actuator wire between the pulley and the moveable component.

Figure 8 shows a side view of an arrangement 800 of pulleys with different inner diameters. As shown in Figure 4A, an actuator comprising multiple pulleys may be used to increase the stroke of the actuator. Figure 8 may be considered to show a set of Tollable pulleys, such as set 414a in Figure 4A, in more detail. The individual Tollable pulleys may not contact each other (i.e. may not be touching), and may only be coupled together by virtue of an SMA actuator wire that is provided around all of the pulleys. An SMA actuator wire 802 is provided around pulleys 804, 806, 808 that form one set of pulleys in the way described above with reference to Figure 4A. The SMA actuator wire 802 is provided around an external diameter or circumference of each of the pulleys 804, 806, 808. Each pulley 804, 806, 808 comprises a smaller axle or similar protrusion 810 of differing size which forms the rolling element of each Tollable pulley. The axle 810 of each pulley 804, 806, 808 is arranged to roll on a surface (not shown). As shown, the axle 810 of pulley 804 has a small diameter D but a large height H. The axle of the second pulley 806 has a larger diameter and a smaller height than the axle of pulley 804. The axle of the third pulley 808 has an even larger diameter and an even smaller height than the axle of pulley 804.

Figure 10 shows an example actuator 1000 comprising two SMA actuator wires and a Tollable pulley. Thus, in embodiments, the actuator may comprise a first SMA actuator wire and a second SMA actuator wire, and one pulley. This example actuator 1000 may be used within a servomotor.

The first SMA actuator wire 1002 may be coupled at a first end to the static component (not shown), and at a second end to the moveable component 1006. The second SMA actuator wire 1004 may be coupled at a first end to the static component, and at a second end to the moveable component 1006. The moveable component 1006 may be provided on the pulley 1008. The first SMA actuator wire 1002 may be arranged to cause the pulley 1008 to rotate in a first direction (e.g. anti-clockwise), and the second SMA actuator wire 1004 may be arranged to cause the pulley 1008 to rotate in a second, opposite direction (e.g. clockwise).

Figures 11A to 11D show various arrangements of SMA actuator wire around a Tollable pulley and how the Tollable pulley may roll. Some or all of these arrangements may enable an actuator having a lower footprint (e.g. smaller size) to be provided. In Figure 11A, SMA actuator wire 1100 is provided around a circumferential edge of pulley 1102. Pulley 1102 comprises an axle 1104 which is arranged to rotate and roll along surface 1106. Here, as the axle 1104 rotates and rolls along surface 1106, and because the axle 1104 is smaller than the pulley 1102, the overall translation of the pulley 1102 is lower than if the circumferential edge of the pulley 1102 rolls on a surface. For example, if the SMA actuator wire 1100 contracts by 1mm, the axle 1104 may only move side-to-side by ±0.3mm, and not by ±lmm. Thus, a smaller actuator may be provided. In Figure 11B, SMA actuator wire 1100 is provided around a circumferential edge of pulley 1102. Pulley 1102 is arranged to rotate and roll along surface 1106. Here, as the pulley 1102 rotates and rolls along surface 1106, a larger rolling surface 1106 is required relative to Figure 11A. For example, if the SMA actuator wire 1100 contracts by lmm, the pulley 1102 may move side-to-side along the surface 1106 by ±lmm. Thus, this arrangement may provide an actuator having a greater stroke compared to an actuator in which the pulleys do not roll, and relative to the arrangement of Figure 11A.

In Figure 11C, SMA actuator wire 1100 is provided around axle 1104 of pulley 1102. Pulley 1102 is arranged to rotate and roll along surface 1106. This arrangement may convert a small movement (rotation) of the axle 1104 into a large translation by the pulley 1102.

In Figure 11D, SMA actuator wire 1100 is provided around a circumferential edge of pulley 1102. Pulley 1102 comprises an axle 1104 which is arranged to locate with a slot 1110 of a mounting surface 1108. When the pulley 1102 rotates, the axle 1104 may move within slot 1110. The slot 1110 may be substantially straight as illustrated, or may be curved. The slot 1110 restricts movement of the pulley 1102. In the arrangements of Figures 11A to 11C, endstops or similar elements may be required to restrict movement of the pulley 1102/axle 1104 along the surface 1106, to prevent rolling to such an extent that the SMA actuator wire is over-stretched (which may lead to breaking).

The actuators described herein may be used in any scenario or apparatus in which a large movement/displacement of a component of the apparatus is required, but where it may not be practical to provide long lengths of SMA actuator wire (e.g. where the actuator needs to be compact or miniature).

Thus, in embodiments there is provided an apparatus comprising: an actuator for moving a component of the apparatus, the actuator comprising: a static component; a moveable component moveable relative to the static component, and coupled to the component of the apparatus; at least one pulley arranged to undergo rotational motion and translational motion and thereby drive movement of the moveable component; and at least one shape memory alloy (SMA) actuator wire coupled to the static component and to the at least one pulley, and arranged to drive the rotational and translational motion of the at least one pulley.

The apparatus may be any one of: a smartphone, a camera, a foldable smartphone, a foldable smartphone camera, an image capture device, a servomotor, a consumer electronic device, a mobile computing device, a laptop, a tablet computing device, a security system, a gaming system, an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device, a drone (aerial, water, underwater, etc.), an aircraft, a spacecraft, a submersible vessel, a vehicle, and an autonomous vehicle. It will be understood that this is a non-exhaustive list of example apparatus.

One example use for the actuator of the present techniques may be in an image capture device. The actuators described herein may be incorporated into an image capture device, and used to move an optical element such that it at least partly covers an aperture of the image capture device. The optical element may be a shutter that may be able to reduce the total amount of light passing through the aperture of the image capture device. The shutter may be able to fully open, partly open, and/or fully close. The optical element may be a filter that may be 10 able to block certain wavelengths of light from passing through the aperture of the image capture device. In an example, the filter may be an infrared cut-off filter.

Further embodiments of the present techniques are set out in the following numbered clauses:

1. An actuator comprising: a static component; a moveable component moveable relative to the static component; at least one pulley arranged to undergo rotational motion and translational motion and thereby drive movement of the moveable component; and at least one shape memory alloy (SMA) actuator wire coupled to the static component and to the at least one pulley, and arranged to drive the rotational and translational motion of the at least one pulley.

2. The actuator according to clause 1 wherein the at least one pulley is arranged to drive translational motion of the moveable component.

3. The actuator according to clause 1 wherein the at least one pulley is arranged to drive rotational motion of the moveable component.

4. The actuator according to clause 1, 2 or 3 wherein the at least one pulley rolls along a surface.

5. The actuator according to clause 4 wherein a circumferential edge of the at least one pulley rolls along the surface.

6. The actuator according to clause 4 wherein an axle of the at least one pulley rolls along the surface.

7. The actuator according to clause 4, 5 or 6 where the surface is substantially flat.

8. The actuator according to clause 4, 5 or 6 where the surface is curved. 9. The actuator according to any one of clauses 1 to 8 wherein the at least one

SMA actuator wire is coupled to an axle of the at least one pulley.

10. The actuator according to any one of clause 1 to 8 wherein the at least one SMA actuator wire is provided around at least part of a circumferential edge of the at least one pulley. 11. The actuator according to any preceding clause further comprising a resilient biasing member to oppose the driving of the moveable component by the at least one pulley.

12. The actuator according to any one of clauses 1 to 11 further comprising two pulleys.

13. The actuator according to any one of clauses 1 to 11 comprising a plurality of pulleys.

14. The actuator according to clause 12 or 13 wherein the pulleys may be different sizes.

15. The actuator according to any preceding clause comprising two SMA actuator wires.

16. The actuator according to any preceding clause where the two SMA actuator wires are opposing wires, such that a first SMA actuator wire is arranged to drive the rotational motion of the at least one pulley in a first direction, and a second SMA actuator wire is arranged to drive the rotational motion of the at least one pulley in a second direction that is opposite to the first direction.

17. The actuator according to clause 1 wherein the actuator comprises a first SMA actuator wire and a second SMA actuator wire, and a first pulley and a second pulley.

18. The actuator according to clause 17 wherein : the first SMA actuator wire is coupled at a first end to the static component and at a second end to the moveable component, and a portion of the first SMA actuator wire is provided around the first pulley; and the second SMA actuator wire is coupled at a first end to the static component and at a second end to the moveable component, and a portion of the second SMA actuator wire is provided around the second pulley, wherein the moveable component is provided between the first and second pulley.

19. The actuator according to clause 18 wherein : the first end of the first SMA actuator wire is coupled to a first side of the static component; and the first end of the second SMA actuator wire is coupled to a second side of the static component, where the second side of the static component is opposite the first side.

20. The actuator according to clause 19 further comprising: a first surface upon which the first pulley is arranged to undergo rotational motion and translational motion; and a second surface upon which the second pulley is arranged to undergo rotational and translational motion. 21. The actuator according to any one of clauses 18, 19 or 20 wherein a length of the first SMA actuator wire is substantially perpendicular to the first surface, and a length of the second SMA actuator wire is substantially perpendicular to the second surface.

22. The actuator according to any one of clauses 18 to 21 wherein a length of the first SMA actuator wire forms a first acute angle with the first surface, and a length of the second SMA actuator wire forms a second acute angle with the second surface.

23. The actuator according to clause 22 wherein the first acute angle and the second acute angle are equal.

24. The actuator according to clause 18 wherein : the first end of the first SMA actuator wire and the first end of the second SMA actuator wire are both coupled to a side of the static component.

25. The actuator according to clause 24 further comprising: a first surface upon which the first pulley is arranged to undergo rotational motion and translational motion; and a second surface upon which the second pulley is arranged to undergo rotational and translational motion.

26. The actuator according to clause 25 wherein the first surface forms a first angle relative to the side of the static component, and the second surface forms a second angle relative to the side of the static component.

27. The actuator according to clause 26 where the first angle and the second angle are equal.

28. The actuator according to clause 1 wherein the actuator comprises a first length of SMA actuator wire and a second length of SMA actuator wire, and at least two pulleys.

29. The actuator according to clause 28 wherein the static component comprises a first side and a second side, and the moveable component is arranged on a surface of the static component between the first and second sides of the static component.

30. The actuator according to clause 29 wherein : the first length of SMA actuator wire is coupled at a first end to the first side of the static component, and at a second end to the moveable component; and the second length of SMA actuator wire is coupled at a first end to the second side of the static component, and at a second end to the moveable component. 31. The actuator according to clause 30 wherein : at least one pulley is provided at the second end of the static component, and a portion of the first length of SMA actuator wire is provided around the at least one pulley at the second end; and at least one pulley is provided at the first end of the static component, and a portion of the second length of SMA actuator wire is provided around the at least one pulley at the first end.

32. The actuator according to clause 30 or 31 wherein the actuator comprises a first set of pulleys, a second set of pulleys, a third set of pulleys and a fourth set of pulleys, each of which comprises at least one pulley.

33. The actuator according to clause 32 wherein : the first set of pulleys is provided at the second end of the static component, the second set of pulleys is provided at the first end of the static component, and the first length of SMA actuator wire is wound around a pulley of the first set of pulleys and a pulley of the second set of pulleys in an alternating manner; and the third set of pulleys is provided at the first end of the static component, the fourth set of pulleys is provided at the second end of the static component, and the second length of SMA actuator wire is wound around a pulley of the third set of pulleys and a pulley of the fourth set of pulleys in an alternating manner.

34. The actuator according to any one of clauses 31 to 33 wherein each pulley is provided in an individual slot in the static component.

35. The actuator according to any one of clauses 29 to 34 further comprising : an electrical terminal on the surface of the static component on which the moveable component is arranged; and an expandable electrical connector to couple the moveable component to the electrical terminal.

36. The actuator according to any one of clauses 28 to 35 further comprising a sliding element coupled to the moveable component and arranged to undergo translational motion.

37. The actuator according to clause 36 wherein the sliding element is arranged to convert translational motion into rotational motion.

38. The actuator according to any one of clauses 28 to 37 where the first length of SMA actuator wire and second length of SMA actuator wire are portions of a single SMA actuator wire.

39. The actuator according to any one of clauses 28 to 37 where the first length of SMA actuator wire is provided by a first SMA actuator wire, and the second length of SMA actuator wire is provided by a second SMA actuator wire. 40. The actuator according to clause 1 wherein the actuator comprises a first SMA actuator wire and a second SMA actuator wire, and one pulley.

41. The actuator according to clause 40 wherein : the first SMA actuator wire is coupled at a first end to the static component, and at a second end to the moveable component; and the second SMA actuator wire is coupled at a first end to the static component, and at a second end to the moveable component; wherein the moveable component is provided on the pulley, and wherein the first SMA actuator wire is arranged to cause the pulley to rotate in a first direction, and the second SMA actuator wire is arranged to cause the pulley to rotate in a second, opposite direction.

42. The actuator according to clause 1 wherein the actuator comprises one SMA actuator wire and one pulley.

43. The actuator according to clause 42 wherein : the pulley is arranged to undergo rotational motion and translational motion, and is provided in an abutting relationship between the static component and the moveable component and is operatively arranged to roll along the static component and thereby drive translational movement of the moveable component; the SMA actuator wire is coupled to the static component and to the pulley, and arranged to drive the rotational and translational motion of the pulley.

44. The actuator according to clause 43 wherein : the pulley comprises a plurality of teeth along a circumferential edge of the pulley; the static component comprises a surface bearing a series of teeth that engage with the teeth of the pulley; and the moveable component comprises a surface bearing a series of teeth that engage with the teeth of the pulley.

45. The actuator according to clause 43 further comprising: at least two straps, where a first strap is coupled at one end to the static component and at another end to the pulley, and a second strap is coupled at one end to the moveable component and at another end to the pulley.

46. The actuator according to clause 44 or 45 wherein the SMA actuator wire is coupled at a first end to the static component and is wrapped around an axle of the pulley.

47. The actuator according to any one of clauses 42 to 46 wherein the pulley is arranged to convert rotational motion into translational motion.

48. The actuator according to clause 42 wherein the SMA actuator wire is coupled at a first end to the static component and at a second end to the moveable component, where a portion of the SMA actuator wire is provided around the pulley.

49. The actuator according to clause 48 further comprising : a surface upon which the pulley is arranged to undergo rotational motion and translational motion.

50. The actuator according to clause 49 wherein a first length of the SMA actuator wire between the static component and the pulley is substantially parallel to a second length of the SMA actuator wire between the pulley and the moveable component.

51. The actuator according to clause 49 wherein a first length of the SMA actuator wire between the static component and the pulley is substantially non- parallel to a second length of the SMA actuator wire between the pulley and the moveable component. Those skilled in the art will appreciate that while the foregoing has described what is considered to be the best mode and where appropriate other modes of performing present techniques, the present techniques should not be limited to the specific configurations and methods disclosed in this description of the preferred embodiment. Those skilled in the art will recognise that present techniques have a broad range of applications, and that the embodiments may take a wide range of modifications without departing from any inventive concept as defined in the appended claims.

Claims

1. An actuator comprising:

a static component;

a moveable component moveable relative to the static component;

at least one pulley arranged to undergo rotational motion and translational motion and thereby drive movement of the moveable component; and

at least one shape memory alloy (SMA) actuator wire coupled to the static component and to the at least one pulley, and arranged to drive the rotational and translational motion of the at least one pulley.

2. The actuator as claimed in claim 1 wherein the at least one pulley is arranged to drive translational motion of the moveable component.

3. The actuator as claimed in claim 1 wherein the at least one pulley is arranged to drive rotational motion of the moveable component.

4. The actuator as claimed in claim 1, 2 or 3 wherein the at least one pulley rolls along a surface.

5. The actuator as claimed in claim 4 wherein a circumferential edge of the at least one pulley rolls along the surface.

6. The actuator as claimed in claim 4 wherein an axle of the at least one pulley rolls along the surface.

7. The actuator as claimed in claim 4, 5 or 6 where the surface is substantially flat.

8. The actuator as claimed in claim 4, 5 or 6 where the surface is curved.

9. The actuator as claimed in any one of claims 1 to 8 wherein the at least one SMA actuator wire is coupled to an axle of the at least one pulley.

10. The actuator as claimed in any one of claims 1 to 8 wherein the at least one SMA actuator wire is provided around at least part of a circumferential edge of the at least one pulley.

11. The actuator as claimed in any preceding claim further comprising a resilient biasing member to oppose the driving of the moveable component by the at least one pulley.

12. The actuator as claimed in any one of claims 1 to 11 further comprising two pulleys.

13. The actuator as claimed in any one of claims 1 to 11 comprising a plurality of pulleys.

14. The actuator as claimed in claim 12 or 13 wherein the pulleys may be different sizes.

15. The actuator as claimed in any preceding claim comprising two SMA actuator wires.

16. The actuator as claimed in any preceding where the two SMA actuator wires are opposing wires, such that a first SMA actuator wire is arranged to drive the rotational motion of the at least one pulley in a first direction, and a second SMA actuator wire is arranged to drive the rotational motion of the at least one pulley in a second direction that is opposite to the first direction.

17. The actuator as claimed in claim 1 wherein the actuator comprises a first SMA actuator wire and a second SMA actuator wire, and a first pulley and a second pulley.

18. The actuator as claimed in claim 1 wherein the actuator comprises a first length of SMA actuator wire and a second length of SMA actuator wire, and at least two pulleys.

19. The actuator as claimed in claim 1 wherein the actuator comprises a first SMA actuator wire and a second SMA actuator wire, and one pulley.

20. The actuator as claimed in claim 1 wherein the actuator comprises one SMA actuator wire and one pulley.

21. An actuator comprising:

a static component;

a moveable component moveable relative to the static component;

a pulley arranged to undergo rotational motion and thereby drive rotational movement of the moveable component;

a first shape memory alloy (SMA) actuator wire coupled at one end to the static component and at another end to the pulley, and arranged to drive the rotational motion of the pulley in a first direction; and

a second SMA actuator wire coupled at one end to the static component and at another end to the pulley, and arranged to drive the rotational motion of the pulley in a second direction that is opposite to the first direction.

22. An actuator comprising:

a static component;

a moveable component moveable relative to the static component;

a pulley arranged to undergo rotational motion and translational motion, provided in an abutting relationship between the static component and the moveable component and operatively arranged to roll along the static component and thereby drive translation movement of the moveable component; and

a shape memory alloy (SMA) actuator wire coupled to the static component and to the pulley, and arranged to drive the rotational and translational motion of the pulley.

23. An apparatus comprising :

an actuator according to claims 1 to 22 for moving a component of the apparatus, where the moveable component of the actuator is coupled to the component of the apparatus.

24. The apparatus as claimed in claim 23 where the apparatus is any one of: a smartphone, a camera, a foldable smartphone, a foldable image capture device, a foldable smartphone camera, an image capture device, a servomotor, a consumer electronic device, a mobile computing device, a laptop, a tablet computing device, a security system, a gaming system, an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device, a drone, an aircraft, a spacecraft, a submersible vessel, a vehicle, and an autonomous vehicle.