Actuator assembly and camera assembly

Abstract

The utility model relates to an actuator assembly and a camera assembly. The actuator assembly includes: a first portion; a second portion arranged to be movable relative to the first portion; and a plurality of actuating units. At least one of the actuating units includes: a body portion; an SMA element connected between the main body portion and the other one of the first portion and the second portion; a force modifying element connected between the body portion and the other of the first and second portions; and a coupling link connected between the main body portion and one of the first portion and the second portion. Each actuation unit includes an SMA element disposed along a first side of the actuator assembly and a coupling link disposed along a second side of the actuator assembly, wherein the second side is adjacent the first side. The plurality of actuation units are arranged such that, for each direction along each axis of the Cartesian coordinate system, there is at least one actuation force having a non-zero component along that direction.

Description

TECHNICAL FIELD

[0001] The present application relates to an actuator assembly having one or more actuation units, each actuation unit comprising a shape memory alloy (SMA) element. BACKGROUND

[0002] SMA actuator assemblies can be used in various applications for moving a movable part relative to a support structure.

[0003] For example, WO 2013 / 175197 A1 describes a camera in which four SMA actuator wires are arranged to move a lens element relative to an image sensor in a plane perpendicular to the optical axis of the lens element, thereby enabling optical image stabilization. WO 2010 / 029316 A1 describes SMA actuator wires for providing OIS in a camera by tilting a camera module. WO 2011 / 104518 A1 describes an actuator assembly having eight SMA wires that enables position control of a movable element with multiple degrees of freedom.

[0004] Typically, the range of movement (also referred to as “stroke”) of such SMA actuator assemblies is limited by the maximum contraction of the SMA wire, and the actuation force is limited by the maximum force that the SMA wire can generate. To increase the range of movement or the actuation force, longer or thicker SMA wires can be used, but this can come at the cost of increased cost, size and / or power, which can not be practical in miniature applications.

[0005] WO 2022 / 084699 A1 discloses an actuator assembly comprising at least one actuation unit (containing a SMA wire) that, upon actuation, moves a movable part relative to a support structure. The actuation unit can be configured to amplify the range of movement of the movable part, to amplify the actuation force acting on the movable part, or to redirect the force exerted by the SMA wire. SUMMARY

[0006] According to an aspect of the present utility model, there is provided an actuator assembly comprising:

[0007] a first part;

[0008] a second part arranged to be movable relative to the first part;

[0009] a plurality of actuation units, each actuation unit being configured to exert an actuation force to one of the first part and the second part, the first part and the second part being capable of moving the second part relative to the first part, wherein at least one of the actuation units comprises:

[0010] a body portion;

[0011] an SMA element connected between the body portion and the other of the first portion and the second portion and configured to apply an input force to the body portion upon actuation; and

[0012] a force-modifying element connected between the body portion and the other of the first portion and the second portion and configured to modify the input force to produce an actuation force; and

[0013] a coupling link connected between the body portion and one of the first portion and the second portion, wherein the coupling link is configured to transmit the actuation force from the body portion to the one of the first portion and the second portion, and wherein the coupling link is compliant in a direction perpendicular to the actuation force;

[0014] wherein each actuation unit comprises an SMA element arranged along a first side of the actuator assembly and a coupling link arranged along a second side of the actuator assembly, wherein the second side is adjacent to the first side; and

[0015] wherein the plurality of actuation units are arranged such that for each direction along each axis of a Cartesian coordinate system (+x, -x, +y, -y, +z, -z), there is at least one actuation force having a non-zero component along that direction.

[0016] In some embodiments, the actuator assembly comprises a main axis extending through the actuator assembly, and wherein the first side and the second side of the actuator assembly are arranged around the main axis.

[0017] In some embodiments, the actuator assembly comprises four sides arranged around the main axis, optionally wherein adjacent sides are perpendicular, and thus the four sides form a quadrilateral shape when viewed along the main axis.

[0018] In some embodiments, the input force applied by each SMA element of each actuation unit is in a direction substantially perpendicular to the main axis, and wherein the actuation force of each actuation unit has a first component parallel to the main axis and a second component perpendicular to the main axis.

[0019] In some embodiments, the input force of each actuation unit is in a direction substantially perpendicular to the respective actuation force when viewed along the main axis.

[0020] In some embodiments, the actuator assembly comprises eight actuation units.

[0021] In some embodiments, the actuation units are arranged in pairs, and wherein, for each pair of actuation units, the SMA element is arranged along the same side of the actuator assembly.

[0022] In some embodiments, for each pair of actuation units, the SMA element is configured to, upon actuation, exert an input force towards the opposite longitudinal end of the side along which the SMA element is arranged.

[0023] In some embodiments, for each pair of actuation units, the SMA element is configured to, upon actuation, exert an input force towards the same longitudinal end of the side along which the SMA element is arranged.

[0024] In some embodiments, for each pair of actuation units, the coupling link is arranged along the opposite side of the actuator assembly.

[0025] In some embodiments, for each pair of actuation units, the coupling link is configured to transmit a substantially parallel actuation force to the one of the first and second portions.

[0026] In some embodiments, for each pair of actuation units, the coupling link is arranged along the same side of the actuator assembly.

[0027] In some embodiments, a first pair of actuation units are each arranged to exert an actuation force along a first transverse axis having a component along a first direction, wherein the first transverse axis is perpendicular to the main axis; a second pair of actuation units are each arranged to exert an actuation force along the first transverse axis having a component along a second direction opposite to the first direction; a third pair of actuation units are each arranged to exert an actuation force along a second transverse axis having a component along a third direction, wherein the second transverse axis is perpendicular to the main axis and the first transverse axis; and a fourth pair of actuation units are each arranged to exert an actuation force along the second transverse axis having a component along a fourth direction opposite to the third direction.

[0028] In some embodiments, the first and second pairs of actuation units are each arranged to exert an actuation force along the main axis having a component along a fifth direction; the third and fourth pairs of actuation units are each arranged to exert an actuation force along the main axis having a component along a sixth direction opposite to the fifth direction.

[0029] In some embodiments, each pair of actuation units comprises a first actuation unit and a second actuation unit, and wherein: the first actuation unit in each pair of actuation units is arranged to exert an actuation force along the primary axis having a component along a fifth direction; and the second actuation unit in each pair of actuation units is arranged to exert an actuation force along the primary axis having a component along a sixth direction opposite to the fifth direction.

[0030] In some embodiments, the body portions, the SMA elements and the force modifying elements of the first and second pairs of actuation units are arranged along one or more surfaces generally facing the fifth direction along the primary axis; and the body portions, the SMA elements and the force modifying elements of the third and fourth pairs of actuation units are arranged along one or more surfaces generally facing the sixth direction along the primary axis.

[0031] In some embodiments, the body portions, the SMA elements and the force modifying elements of each of the first pair of actuation units are arranged along one or more surfaces generally facing the fifth direction along the primary axis; and the body portions, the SMA elements and the force modifying elements of each of the second pair of actuation units are arranged along one or more surfaces generally facing the sixth direction along the primary axis.

[0032] In some embodiments, each actuation unit has an angular range about the primary axis that is greater than 90°.

[0033] In some embodiments, a portion of a first actuation unit and a portion of a second actuation unit in each pair of actuation units overlap each other when viewed along the primary axis.

[0034] In some embodiments, an overlapping portion of the first actuation unit and the second actuation unit in each pair of actuation units has an angular range about the primary axis that is less than 90°.

[0035] In some embodiments, an angular range of each actuation unit about the primary axis overlaps an angular range of two or more other actuation units about the primary axis.

[0036] In some embodiments, the SMA element and the coupling link of any given actuation unit are arranged in a plane having a normal at an oblique angle relative to the primary axis.

[0037] According to another aspect of the present application, there is provided a camera assembly, the camera assembly comprising:

[0038] the actuator assembly described above;

[0039] one or more lenses comprised in one of the first and second parts of the actuator assembly; and

[0040] an image sensor comprised in the other of the first and second parts of the actuator assembly;

[0041] wherein the actuator assembly is configured to move the one or more lenses and the image sensor relative to each other in three translational degrees of freedom.

[0042] According to another aspect of the present application, there is provided a camera assembly, the camera assembly comprising:

[0043] the actuator assembly described above; and

[0044] a support structure comprising one of the first and second parts of the actuator assembly;

[0045] a module comprised in the other of the first and second parts of the actuator assembly, wherein

[0046] the module comprises one or more lenses and an image sensor;

[0047] wherein the actuator assembly is configured to rotate the module relative to the support structure in two or more rotational degrees of freedom. BRIEF DESCRIPTION OF DRAWINGS

[0048] Certain embodiments of the present application will now be described, by way of example only, with reference to the accompanying drawings in which:

[0049] Figures 1A-1E is a schematic cross-sectional view of different variants of a camera module incorporating an actuator assembly;

[0050] Figure 2 is a schematic perspective view of an actuator assembly;

[0051] Figure 3A and Figure 3B is a perspective and plan view of an actuator unit forming part of an actuator assembly, while Figure 3C is a plan view of another such actuator unit;

[0052] Figure 4 is a schematic plan view of an arrangement of four actuator units;

[0053] Figure 5 is a schematic perspective view of an arrangement of eight actuator units;

[0054] Figure 6 is a perspective view of an actuator assembly according to the present disclosure;

[0055] Figure 7 is Figure 6 is a schematic perspective view of an actuator assembly according to the present disclosure;

[0056] Figure 8 is Figure 6 is another view of the actuator assembly of

[0057] Figure 9 is a perspective view of another actuator assembly according to the present disclosure;

[0058] Figure 10 is a schematic perspective view of an actuator assembly according to the present disclosure; Figure 9

[0059] is Figure 11 is another view of the actuator assembly of Figure 9

[0060] is a schematic perspective view of another actuator assembly according to the present disclosure; and Figure 12

[0061] is Figure 13 is an alternative perspective view of the actuator assembly of Figure 6 DETAILED DESCRIPTION

[0062] Camera module

[0063] Different variants of an apparatus 1 comprising an actuator assembly 2 are schematically illustrated. The apparatus 1 is for example a camera module 1. Typically, the apparatus 1 will be incorporated into a portable electronic device such as a smartphone. Miniaturization can therefore be an important design criterion. Figures 1A-1E

[0064] The actuator assembly 2 is schematically illustrated. The actuator assembly 2 comprises a support structure 10 and a movable portion 20. The movable portion 20 is movable relative to the support structure 10. When the actuator assembly 2 is comprised in for example the apparatus 1, the support structure 10 can be fixed relative to a main body of the apparatus 1. However, typically, the support structure 10 need not be stationary and can be movable relative to or within the apparatus 1. The actuator assembly 2 comprises one or more actuation units 30. Each actuation unit 30 is configured to exert an actuation force to the movable portion 20, which actuation force is capable of moving the movable portion 20 relative to the support structure 10. Figure 2

[0065] ​The movable portion 20 can be supported on the support structure 10 solely by the actuation unit 30 (e.g. suspended from the support structure 10). Alternatively, the actuator assembly 2 can comprise a bearing arrangement 40 which supports the movable portion 20 on the support structure 10. The actuation unit 30 and the bearing arrangement 40 can together support the movable portion 20 on the support structure 10. The bearing arrangement 40 can be of any suitable form which allows the movable portion 20 to move relative to the support structure 10 with one or more degrees of freedom (DOFs). The actuation unit 30 and / or the bearing arrangement 40 can constrain, i.e. reduce or prevent, other degrees of freedom of movement of the movable portion 20 relative to the support structure 10. To this end, the bearing arrangement 40 can for example comprise one or more of the following bearings: rolling bearings (such as ball bearings), flexible bearings (i.e. flexures or other resilient elements which guide movement) or sliding (i.e. sliding contact) bearings.

[0066] A principal axis P can be defined with reference to the actuator assembly 2 and / or the support structure 10. The principal axis P can extend through the actuator assembly 2, e.g. through a centre of the actuator assembly 2. In some examples, the actuator assembly 2, the support structure 10 and / or the movable portion 20 extend predominantly in a direction perpendicular to the principal axis P. In other words, the extent of the actuator assembly 2, the support structure 10 and / or the movable portion 20 along the principal axis P is less than their extent along any direction perpendicular to the principal axis P. The principal axis P can be a longitudinal axis of the actuator assembly 2 and / or the support structure 10. Alternatively or additionally, the support structure 10 and / or the movable portion 20 can comprise a planar component which extends perpendicular to the principal axis P. Alternatively or additionally, in examples in which the apparatus 1 comprises an optical element (such as the lens assembly 3) having an optical axis or an imaging element (such as the imager sensor 4) having an imaging axis, the principal axis P can be parallel to and / or can coincide with such an axis when the movable portion 20 is in a central position or orientation (e.g. see Figure 1A ).

[0067] In general, the movable portion 20 can be movable relative to the support structure 10 with up to six degrees of freedom (DOFs). In the context of describing degrees of freedom of movement, the principal axis P can also be referred to as a z-axis, and two further axes perpendicular to the principal axis P and to each other can be referred to as x- and y-axes. The movable portion 20 can be movable relative to the support structure 10 in all or any subset (including just one) of the following degrees of freedom:

[0068] - Tx and Ty: translational movement in the x-y plane. In other words, the movable part 20 can be moved independently along the x- and y-axes. The movable part 20 can be moved within a movement range to any position in the x-y plane. Instead of such a planar movement, the movable part 20 can be moved linearly, e.g. along the x- or y-axis.

[0069] - Rx and Ry: rotational movement (or simply rotation or tilting) around the x- and y-axes. In other words, the movable part 20 can be rotated around any line perpendicular to the principal axis P. The movable part 20 can be rotated within a movement range to any rotational position (i.e. to any orientation). Instead of such a two-axis rotation, the movable part 20 can be rotated around a single axis, e.g. around the x- or y-axis.

[0070] - Tz: translational movement along the z-axis. The movable part 20 can be moved within a movement range along the z-axis to any translational position.

[0071] - Rz: rotational movement (or simply rotation) around the z-axis. The movable part 20 can be rotated within a movement range to any rotational position (i.e. to any orientation).

[0072] In some examples, the movable part 20 can be supported, e.g. by the bearing device 40, so as to allow translational movement (Tx, Ty) in the x-y plane and / or rotational movement (Rz) around the z-axis. The translational movement (Tz) along the z-axis and the rotational movement (Rx, Ry) around the x- and y-axes can be constrained. For example, such a support can be provided with a bearing device 40 having suitable means of ball bearings or sliding bearings creating a bearing force in the +z direction and biasing means creating a biasing force in the -z direction. Examples of actuator assemblies with such a bearing device are disclosed in WO 2013 / 175197 Al and WO 2017 / 072525 Al, each of which is incorporated herein by reference.

[0073] In some examples, the movable part 20 can be supported to allow tilting (Rx, Ry) around the x- and y-axes and optionally rotation (Rz) around the z-axis. Other movement degrees of freedom (i.e. Tx, Ty, Tz, Rz or Tx, Ty, Tz) can be constrained. Such a support can be provided by the bearing device 40, e.g. in the form of a gimbal. Examples of such a bearing device 40 are disclosed in WO 2021 / 209770 Al, which is incorporated herein by reference. Alternatively, such a support can be provided by the actuation unit 30 only, similar to WO 2011 / 104518 Al, which discloses an actuator assembly with 8 SMA wires connected between the support structure 10 and the movable part 20. WO 2011 / 104518 Al is incorporated herein by reference.

[0074] In some examples, the movable part 20 can be supported to allow three- dimensional translational movement (Tx, Ty, Tz) while rotational movement (Rx, Ry, Rz) can be constrained. Such support can be provided by a bearing device 40, for example in the form of nested linear bearings. Examples of such bearing devices 40 are disclosed in WO 2021 / 209769 Al, which is incorporated herein by reference. Alternatively, such support can be provided by the actuation unit 30 only, similar to WO 2011 / 104518 Al.

[0075] The movable part 20 can alternatively or additionally move in other degrees of freedom. The movable part 20 can move in degrees of freedom that are a combination of any two or more of Tx, Ty, Tz, Rx, Ry, and Rz. For example, the movable part 20 can move along a helical path around the z-axis (i.e., move helically), and thus simultaneously move along the z-axis and rotate around the z-axis. In other words, Tz and Rz movement can be coupled. Examples of such helical actuator assemblies are disclosed in WO 2019 / 243849 Al, which is incorporated herein by reference.

[0076] The actuation unit 30 is connected between the support structure 10 and the movable part 20. The actuation unit 30 is arranged to exert an actuation force F (see, e.g., Fx, Fy, Fz) between the movable part 20 and the support structure 10. Figure 4 and Figure 5 Selectively varying the actuation force F can cause the movable part 20 to move relative to the support structure 10, e.g., within the degrees of freedom allowed by the bearing device 40. Thus, the actuation unit 30 is able to drive movement of the movable part 20 relative to the support structure 10.

[0077] The bearing device 40 can cause the movable part 20 to move in a direction that is different from the direction of the actuation force F. In a simple example in this regard, one component of each actuation force F causes movement of the movable part 20, and the other component of each actuation force F acts against a bearing force generated by the bearing device 40.

[0078] Referring back to Fig. 1, the camera module 1 further comprises a lens assembly 3 and an image sensor 4. The lens assembly 3 comprises one or more lenses configured to focus an image on the image sensor 4. The lens assembly 3 defines an optical axis O. The lens assembly 3 can comprise a lens carrier supporting the one or more lenses, e.g., in the form of a cylindrical body. The image sensor 4 captures images and can be of any suitable type, e.g., a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) device. The camera module 1 can be a compact camera module, with each lens having a diameter of 20 mm or less, e.g., 12 mm or less.

[0079] In a first variant of the camera module 1 shown in Figure 1A In the (“sensor shift”) variant of the camera module 1 shown in

[0080] In a second variant of the camera module 1 shown in Figure 1B In the (“lens shift”) variant of the camera module 1 shown in

[0081] In both variants, the actuator assembly 2 is configured to move the lens assembly 3 relative to the image sensor 4 in any direction in a plane perpendicular to the principal axis P and thus to the optical axis O. This movement has the effect of moving the image on the image sensor 4 and enables optical image stabilization (OIS) to be implemented in the camera module 1. In the sensor shift variant, the movable part 20 can also be rotated about the principal axis P in order to be able to compensate for rolling as well.

[0082] In a third variant of the camera module 1 shown in Figure 1C In the (“module tilt”) variant of the camera module 1 shown in

[0083] In a fourth variant of the camera module 1 shown in Figure 1D In the (“auto focus”) variant of the camera module 1 shown in

[0084] In some examples (not shown), the camera module 1 can comprise a first actuator assembly for providing OIS as shown in Figures 1A-1C and a second actuator assembly for providing AF as shown in Figure 1DA second actuator assembly of the AF is shown. One or both of the first and second actuator assemblies can correspond to an actuator assembly 2 as described herein. One of the first and second actuator assemblies can be another type of SMA actuator assembly or can be a non-SMA actuator assembly such as a voice coil motor (VCM) actuator assembly. As will be appreciated, in the lens shift and module tilt variants, the support structure 10 of the second actuator assembly 2 is fixed to (or corresponds to) the movable portion 20 of the first actuator assembly 2.

[0085] In Figure 1E In the ("AF+OIS") variant shown, the movable portion 20 includes a lens assembly 3 and the actuator assembly 2 produces three-dimensional translational movement of the movable portion 20 relative to the support structure 10 so that both AF and OIS can be implemented using one actuator assembly 2.

[0086] Other variants are also possible. For example, in the autofocus variant or the AF+OIS variant, the movable portion 20 can include the image sensor 4 instead of the lens assembly 3. The camera module 1 can include a combination of the features described above, for example (a) lens shift and sensor shift, (b) module tilt and lens shift or sensor shift and autofocus, or (c) module tilt and AF+OIS.

[0087] The camera module 1 also includes a controller 8. The controller 8 can be implemented in the form of an integrated circuit (IC) chip. The controller 8 generates drive signals for the actuation unit 30, in particular for the SMA wires 34 forming part of the actuation unit 30. SMA material has the property that upon heating it undergoes a solid-state phase change that causes the SMA material to contract. Thus, applying a drive signal to the SMA wires 34, thereby heating the SMA wires 34 by causing a current to flow, will cause the SMA wires 34 to contract and thus actuate the actuation unit 30 to move the movable portion 20. The drive signal is selected to drive movement of the movable portion 20 in a desired manner, for example in order to implement OIS by stabilizing an image sensed by the image sensor 4, or to implement AF / zoom by adjusting the focus of an image sensed by the image sensor 4. The controller 8 provides the generated drive signals to the SMA wires 34.

[0088] Optionally, the camera module 1 also includes a motion sensor (not shown), which can include a 3-axis gyroscope and a 3-axis accelerometer. The motion sensor can generate a signal representing motion (in particular vibration or "shaking") of the camera module 1, which can be processed to generate a signal representing a desired movement of the movable portion 20 to compensate for such shaking. The controller 8 receives such a signal and can generate a drive signal for the SMA wires 34 to implement OIS.

[0089] Although the actuator assembly 2 is described in connection with a camera module 1, it will be appreciated that the actuator assembly 2 can be used in any device in which movement of a movable part 20 relative to a support structure 10 is desired, for example to provide haptic feedback in a haptic feedback device or to move a projector or display in an augmented reality (AR) or virtual reality (VR) device.

[0090] Actuation unit

[0091] Figure 3A A perspective view showing an example of an actuation unit 30 is shown. Figure 3B A portion of the actuation unit 30 is shown in plan view.

[0092] A single actuation unit 30 is shown in Figure 3A and Figure 3B However, it will be appreciated that the actuator assembly 2 typically has a plurality of actuation units 30, each of which can comprise the same components as described in Figure 3A and Figure 3B

[0093] The actuation unit 30 comprises a body portion 31 to which a number of other components of the actuation unit 30 are connected, as described below. Typically, the body portion 31 is relatively rigid compared to the other components of the actuation unit and does not deform significantly upon actuation of the actuation unit 30. In some examples, the body portion 31 is not a distinct part of the actuation unit 30. For example, the body portion 31 can be defined as part of one of the other components of the actuation unit 30 or merely as a point of connection between the other components of the actuation unit 30.

[0094] The actuation unit 30 further comprises a force-modifying flexure 32, also referred to as a force-modifying element. The force-modifying flexure 32 is connected between the body portion 31 and the support structure 10. One end of the force-modifying flexure 32 is connected with the body portion 31. The other end of the force-modifying flexure 32 is connected to the support structure 10, for example via a foot portion 36. The foot portion 36 is fixed relative to the support structure 10. The force-modifying flexure 32 allows the body portion 31 to pivot relative to the support structure 10 about an effective pivot point P. Although the effective pivot point P is shown in Figure 3B as being positioned in the middle of the force-modifying flexure 32, the effective pivot point P can have a different position and does not need to be located on the force-modifying flexure 32. This pivotal movement of the body portion 31 relative to the support structure 10 is initially in a direction substantially perpendicular to the force-modifying flexure 32.

[0095] ​The actuation unit 30 further comprises an SMA element 34. In this example, the SMA element 34 is an SMA wire 34. The SMA wire 34 is connected between the body portion 31 and the support structure 10. One end of the SMA wire 34 is connected to the support structure 10, for example by a crimp 15. The other end of the SMA wire 34 is connected to the body portion 31, for example by a crimp 35.

[0096] The actuation unit 30 further comprises a coupling link 33. In this example, the coupling link 33 is a coupling flexure 33. The coupling flexure 33 is connected between the body portion 31 and the movable portion 20. One end of the coupling flexure 33 is connected to the body portion 31. The other end of the coupling flexure 33 is connected to the movable portion 20, optionally via the connection portion 21a. The coupling link 33 transfers or transmits the actuation force F from the body portion 31 to the movable portion 20. The coupling link 33 is deformable (i.e. shapeable) in a direction (or directions) perpendicular to the actuation force F. This allows the movable portion 20 to move in directions other than the direction of the coupling flexure 33 and the force F. This can be required, for example, in cases where different actuation units 30 move the movable portion 20 in different directions.

[0097] In this example, the body portion 31, the force-modifying flexure 32, the coupling flexure 33 and the foot portion 36 are integrally formed from a single piece of material, such as metal. In other examples, one or more or these features, if present, can be formed from different parts or materials.

[0098] The SMA wire 34 is arranged to exert an input force Fi on the body portion 31 when it contracts. The input force Fi acts parallel to the length of the SMA wire 34. The force-modifying flexure 32 and the body portion 31 are arranged to modify the input force Fi so as to produce an actuation force F which is transmitted from the body portion 31 to the movable portion 20 by the coupling flexure 33. In particular, the input force Fi deforms the force-modifying flexure 32, causing the body portion 31 to pivot about an effective pivot point P. Simply put, the force-modifying flexure 32 and the body portion 31 act like a lever. The force-modifying flexure 32 and the body portion 31 can modify the direction and / or magnitude of the input force Fi so as to produce the actuation force F.

[0099] In this example, the coupling flexure 33 is a coupling flexure 33. The coupling flexure 33 is connected between the body portion 31 and the movable portion 20. One end of the coupling flexure 33 is connected to the body portion 31. The other end of the coupling flexure 33 is connected to the movable portion 20, optionally via the connection portion 21a. The coupling link 33 transfers or transmits the actuation force F from the body portion 31 to the movable portion 20. The coupling link 33 is deformable (i.e. shapeable) in a direction (or directions) perpendicular to the actuation force F. This allows the movable portion 20 to move in directions other than the direction of the coupling flexure 33 and the force F. This can be required, for example, in cases where different actuation units 30 move the movable portion 20 in different directions. Figure 3A and Figure 3BIn the illustrated example, the coupling flexure 33 is at an angle of about 90° relative to the SMA wire 34. Further, in this example, the force-modifying flexure 32 is arranged at an angle a of about 30° relative to the SMA wire 34, and the force-modifying flexure 32 is placed in tension when the SMA wire 34 contracts. Thus, upon contraction of the SMA wire 34 and upon deformation of the force-modifying flexure 32, the body portion 31 initially moves at an angle of ~60° (90° - a) relative to the length of the SMA wire 34. Thus, it will be appreciated that in this example, the force is scaled down and the stroke is scaled up, while the direction of the force / movement is changed by an angle of about 90°. In more detail, the scaling down of the force means that the size of the actuation force is smaller than the size of the input force that causes the actuation force. The scaling up of the stroke means that the amount of movement of the coupling link along the length of the coupling link is larger than the amount of contraction of the SMA wire that causes the movement of the coupling link. In other examples, the input force can be scaled up (meaning that the actuation force is larger than the input force), while the stroke can be scaled down (the amount of movement of the coupling link is smaller than the amount of contraction of the SMA wire).

[0100] More generally, the change in direction of the force depends on the ratio of i) the distance Ds from the effective pivot point P to the line along which the SMA wire 34 lies and ii) the distance Dc from the effective pivot point P to the line along which the coupling flexure 33 lies, where Ds is the shortest distance from the pivot point to the line along which the SMA lies, and Dc is the shortest distance from the pivot point to the line along which the coupling link lies. In particular, F / Fi is proportional to Ds / Dc. If the SMA wire 34 lies on a line closer to the effective pivot point P than the line along which the coupling flexure 33 lies, then the input force Fi is scaled down. At the same time, the movement of the movable portion 20 is scaled up, i.e. the movement of the movable portion 20 relative to the length of the SMA wire 34 is increased. Alternatively, if the SMA wire 34 lies on a line further from the effective pivot point P than the line along which the coupling flexure 33 lies, then the input force Fi is scaled up. At the same time, the movement of the movable portion 20 is scaled down, i.e. the movement of the movable portion 20 relative to the length of the SMA wire 34 is decreased. Thus, the actuation unit 30 can be configured to scale up the movement or to scale up the force due to the contraction of the SMA wire 34. The actuation unit 30 can also be configured to change the direction of the input force Fi. In some examples, the actuation unit 30 is configured to change the direction of the input force Fi without changing the size of the force or movement.

[0101] The ratio Ds / Dc depends on the position of the end of the SMA wire 34 that is connected to the body portion 31, and the position of the end of the coupling flexure 33 that is connected to the body portion 31. As an example, the ratio Ds / Dc can be varied by connecting the coupling flexure 33 further to the body portion 31, or by connecting the SMA wire 34 further to the body portion 31. Figure 3BDs / Dc can be increased by increasing the distance Dc from the left side of the body part 31 shown in Fig. 3, thereby reducing Ds / Dc and thus increasing the stroke amplification. The ratio Ds / Dc also depends on the orientation of the SMA wire 34 and the orientation of the coupling flexure 33. Such orientations can be defined with reference to the force-modifying flexure 32 (as above) or any suitable reference line. As an example, the distance Ds can be reduced by angling the SMA wire 34 shown in Fig. 3 so that it is closer to the effective pivot point P through, thereby reducing Ds / Dc and thus increasing the stroke amplification. In general, the amount by which the force-modifying flexure 32 amplifies or reduces the force / stroke of the SMA wire 34 can be tailored by: Figure 3B

[0102] - adjusting the orientation of the SMA wire 34 (and thus the input force Fi);

[0103] - adjusting the position of the connection point between the SMA wire 34 and the body part 31 (and thus the position at which the input force Fi acts on the body part 31);

[0104] - adjusting the orientation of the coupling flexure 33 (and thus the actuation force F); and / or

[0105] - adjusting the position of the connection point between the coupling flexure 33 and the body part 31 (and thus the position at which the body part 31 exerts the actuation force F).

[0106] In some examples, at least one actuation unit 30 (preferably each actuation unit 30) is configured so that the force-modifying flexure 32 and the body part 31 amplify the contraction amount of the SMA wire 34. For example, such amplification can be a multiple of more than 1.5, preferably more than 2, further preferably more than 3. To this end, in the example shown in Figs. 3 and 4, the force-modifying flexure 32 and the body part 31 are arranged so that the effective pivot point P through is closer to the SMA wire 34 than to the connection point between the force-modifying flexure 32 and the body part 31. Figure 3A Figure 3B In the example shown in Figs. 3 and 4, the angle a between the SMA wire 34 and the force-modifying flexure 32 can be in the range of 0 degrees to 45 degrees, preferably in the range of 13 degrees to 40 degrees. However, in general, the angle a can have other values and the connection point of the SMA wire 34 and / or the coupling flexure 33 to the body part 31 can be adjusted to achieve a desired amplification amount.

[0107] As described above, in the example shown in Figs. 3 and 4, the coupling flexure 33 is angled at about 90 degrees with respect to the SMA wire 34. This allows the actuation unit 30 to be folded around a corner of the movable part 20 in a compact manner. The angle between the coupling flexure 33 and the SMA wire 34 can be in the range of 70 degrees to 110 degrees, preferably in the range of 80 degrees to 100 degrees. However, in general, the angle between the coupling flexure 33 and the SMA wire 34 can be outside these ranges. Figure 3A Figure 3B

[0108] ​​​​For example, in the actuation unit 30 shown in Figure 3C In the actuation unit 30 shown in Fig. 1, the force-modifying flexure 32, the coupling flexure 33 and the SMA wire 34 are substantially parallel to each other.

[0109] In the above examples, the actuation unit 30 is arranged in a plane. In particular, at least when the actuator assembly 2 is in the initial configuration, the SMA wire 34, the coupling flexure 33 and the force-modifying flexure 32 are arranged to extend substantially in a common plane. This allows for a compact configuration of the actuation unit 30. When implemented by a plate, the body portion 31 can further be arranged to extend in the plane. However, generally, the components of the actuation unit 30 need not be arranged in a common plane. For example, the SMA wire 34 and / or the coupling flexure 33 can be angled with respect to the plane.

[0110] In the above examples, when the SMA wire 34 is contracted, the force-modifying flexure 32 is put in tension. This reduces the risk of the force-modifying flexure 32 buckling, thereby reducing the risk of damage to the actuator assembly 2 and making the actuator assembly 2 more reliable. However, the force-modifying flexure 32 can instead be arranged to be put under compression when the SMA wire 34 is contracted. With reference to Figure 3B For example, the force-modifying flexure 32 can extend from the connection point between the body portion 31 and the force-modifying flexure 32 to the lower right corner and thus be put under compression when the SMA wire 34 is contracted. Arrangements to put the force-modifying flexure 32 under compression are disclosed in WO 2022 / 084699 Al, which is incorporated herein by reference.

[0111] In the above examples, the force-modifying flexure 32 and the SMA wire 34 are connected at one end to the support structure 10 and the coupling flexure 33 is connected at one end to the movable portion 20. Generally, this arrangement can also be reversed, with the force-modifying flexure 32 and the SMA wire 34 being connected at one end to the movable portion 20 and the coupling flexure 33 being connected at one end to the support structure 10.

[0112] In the above example, the actuation unit 30 comprises a coupling link 33 in the form of a coupling flexure 33. The purpose of the coupling link 33 is to allow the movable part 20 to move in a direction perpendicular to the actuation force F. However, generally, the actuation unit 30 need not comprise a coupling link 33, for example in examples in which the movable part 20 does not move in a direction perpendicular to the actuation force F. Moreover, the coupling link 33 can be implemented by means other than a coupling flexure 33, for example by a ball bearing or a sliding bearing configured to transmit the actuation force F to the movable part 20 while allowing the movable part 20 to move in a direction perpendicular to the actuation force F. Such an alternative example of a coupling link 33 is disclosed in WO 2022 / 084699 Al. The coupling link 33 can be formed by an SMA wire, which can (or can not) be integral with and can (or can not) be driven together with the SMA wire 34.

[0113] Moreover, instead of a force-modifying flexure 32, the actuator assembly can comprise a different type of force-modifying element configured to enable the body part 31 to move relative to the support structure 10 as described above. Such a force-modifying element can comprise, for example, a rigid member having one end connected to the support structure 10 via a suitable pivotal connection (e.g. a pin joint) and the other end connected to the body part 31.

[0114] Arrangement of four actuation units

[0115] Figure 4 A plan view of the example of the actuator assembly 2 is schematically shown, showing the arrangement of the actuation units 30. In this example, the actuator assembly 2 comprises a total of four actuation units 30. The four actuation units 30 can exert the actuation force F between the movable part 20 and the support structure 10. The actuation force F is exerted to the movable part 20 relative to the support structure 10.

[0116] Figure 4 The arrangement of the actuation units 30 of Fig. 4 can for example be used in examples in which the movable part 20 is movable relative to the support structure 10 in a movement plane. Thus, Tx, Ty and optionally Rz movement of the movable part 20 can be allowed.

[0117] Figure 4 The four actuation units 30 of Fig. 4 are in an arrangement in which the actuation force F can be exerted so as to move the movable part 20 relative to the support structure 10 to any position within a movement range. The movement range can be within a movement plane perpendicular to the principal axis P.

[0118] In particular, two actuation units 30 (e.g. Figure 4The top and bottom actuation units in the pair (e.g., 30a, 30b) are arranged to exert actuation forces F in opposite directions parallel to the first axis (e.g., the x-axis). The left and right actuation units in the pair (e.g., 30c, 30d) are arranged to exert actuation forces F in opposite directions parallel to a second axis (e.g., the y-axis) perpendicular to the first axis. By appropriately varying the difference in actuation amount between the opposing actuation units 30, the movable portion 20 can thus be moved independently along the first and second axes. The opposite actuation forces F are not collinear, but are offset from each other in a direction perpendicular to the actuation forces F. Providing opposing actuation units 30 allows the tension in the SMA wires 30 of the respective actuation units 30 to be controlled, allowing more accurate and reliable positioning of the movable portion 20 compared to the case where the actuation units 30 are not opposite each other. Figure 4

[0119] In some examples, none of the actuation forces F are collinear. This allows the arrangement of actuation units 30 to move the movable portion 20 translationally without applying any net torque to the movable portion 20. Thus, the movable portion 20 can be moved translationally within a movement plane without causing the movable portion 20 to rotate within the movement plane. In general, the arrangement of actuation units 30 is able to precisely control the torque or moment about the primary axis P of the movable portion 20. Thus, the actuation units 30 are able to cause the movable portion 20 to rotate (or not rotate) about the primary axis P relative to the support structure.

[0120] In particular, the two actuation units 30 (e.g., 30a, 30b) in the pair are arranged to exert actuation forces F so as to generate a torque or moment about the primary axis P between the movable portion 20 and the support structure 2 in a first direction (e.g., clockwise). The other two actuation units 30 (e.g., 30c, 30d) in the pair are arranged to exert actuation forces F so as to generate a torque or moment about the primary axis P between the movable portion 20 and the support structure 2 in a second, opposite direction (e.g., anticlockwise). This allows the movable portion 20 to be rotated by simultaneously increasing or decreasing the tension in the SMA wires of either of the two actuation units 30. Figure 4 Figure 4

[0121] ​​​As shown, two actuation units 30 can be arranged to exert an actuation force F in a corner of the actuator assembly 2. Another two actuation units 30 can be arranged to exert an actuation force F in another opposite corner of the actuator assembly 2. The actuator assembly 2, in particular the movable portion 20 and / or the support structure 10, can have a square or rectangular footprint. Each actuation unit 30 can be provided on one of the four sides of the actuator assembly 2. In particular, each actuation unit 30 can be curved around a corner of the movable portion 20 such that the SMA wire 34 and the coupling flexure 33 of each actuation unit 30 extend along an adjacent edge of the movable portion 20. Thus, the actuation units 30 may, for example, be configured as in Figure 3A and Figure 3B The four SMA wires 32 of the four actuation units 32 can extend along four different edges of the movable portion 20.

[0122] The arrangement of the actuation forces F exerted between the movable portion 20 and the support structure 10 corresponds to the arrangement of the SMA wires 30 described in WO 2013 / 175197 A1, which is incorporated by reference herein.

[0123] In this example, the actuation forces F are perpendicular to the principal axis P and can be parallel to the plane of movement. However, typically the actuation forces F can be angled with respect to the plane of movement. Thus, the actuation forces F can have a component along the principal axis P. This component along the principal axis P can be resisted by the bearing arrangement 40, for example, to provide movement of the movable portion 20 in the degrees of freedom allowed by the bearing arrangement 40. In some examples, it can even be desirable for the actuation forces F to have a component parallel to the principal axis P, for example, in order to load a sliding bearing or a rolling bearing arranged between the movable portion 20 and the support structure 10.

[0124] Although the arrangement of the actuation units 30 is described as moving the movable portion 20 in the plane of movement (e.g., translating along the x- and y-axes, or rotating about the principal axis P) for illustrative purposes, in other examples the movable portion 20 can be moved differently. For example, the same arrangement of actuation forces F can be used to tilt the movable portion 20 about an axis perpendicular to the principal axis P with respect to the support structure 10 due to appropriate movement constraints provided by the bearing arrangement 40. For example, the bearing arrangement 40 can comprise a plurality of flexures for guiding the tilting of the movable portion 20 about an axis perpendicular to the principal axis P. An example of such a bearing arrangement 40 is described in WO 2022 / 029441 A1, which is incorporated by reference herein.

[0125] Although the actuator assembly 2 is described herein in the context of four actuation units 30, typically the actuator assembly 2 can comprise fewer actuation units 30. For example, the actuator assembly 2 can comprise two actuation units 30, for example Figure 4The two actuation units 30 in the upper left corner can be replaced by, for example, springs exerting a biasing force along the corresponding depicted arrow. Figure 4 The two actuation units 30 in the lower right corner can be replaced by, for example, springs exerting a biasing force along the corresponding depicted arrow.

[0126] Arrangement of eight actuation units

[0127] Figure 5 A perspective view of an actuator assembly 2 with a total of eight actuation units 30 is schematically shown. The eight actuation units 30 can exert an actuation force F between the movable part 20 and the support structure 10. The actuation force F is exerted to the movable part 20 relative to the support structure 10.

[0128] Figure 5 The arrangement of actuation units 30 can for example be used in examples where the movable part 20 is movable relative to the support structure 10 with three translational degrees of freedom (Tx, Ty, Tz) (see Figure 1E ) or with two or three rotational degrees of freedom (Rx, Ry or Rx, Ry, Rz) (see Figure 1C ).

[0129] The eight actuation units 30 can be arranged such that their actuation forces F are oriented or arranged in a manner equivalent to the orientation or arrangement of the forces exerted by the eight SMA wires in the actuator assembly disclosed in WO 2011 / 104518 Al.

[0130] More specifically, the actuation forces F (for example, when visualized as vectors at a particular position in space) are arranged on each of four sides (i.e., a first side, a second side, a third side, and then a fourth side) around a principal axis P. When viewed perpendicularly from the principal axis P, the two actuation forces F on each side are inclined in opposite directions relative to a plane perpendicular to the principal axis P. The four sides on which the actuation forces F are arranged extend in a ring around the principal axis P. In this example, the adjacent sides are perpendicular to each other, and the four sides form a square when viewed along the principal axis P, but the four sides can alternatively take a different, for example, quadrilateral shape. In this example, the actuation forces F are parallel to the outer surface of a square envelope surface of the movable part 20, but this is not essential.

[0131] The four actuation forces F including one on each side form a “first” group with components in one direction (“up” or +z), and the other four actuation forces F form a “second” group with components in the opposite direction (“down” or -z). In this text, “up” and “down” refer to opposite directions along the principal axis.

[0132] These actuation forces F have a symmetrical arrangement in which their magnitude and tilt angle are the same, such that the first and second sets of actuation forces F are each arranged with two-fold rotational symmetry about the primary axis P.

[0133] As a result of this symmetrical arrangement, different combinations of actuation forces F are able to drive movement of the movable portion 20 with multiple degrees of freedom, as follows.

[0134] The first set of actuation forces F, when produced together, drive movement upwards (+z), while the second set of actuation forces F, when produced together, drive movement downwards (-z).

[0135] Within each set, adjacent pairs of actuation forces F, when produced differently, drive tilting about a lateral axis perpendicular to the primary axis P (Rxor Ry). Tilting in any direction can be achieved as a linear combination of tilting about both lateral axes.

[0136] A set of four actuation forces F, comprising two actuation forces F from each set, when produced together, drive movement along a lateral axis perpendicular to the primary axis P (Txor Ty). Movement in any direction perpendicular to the primary axis z can be achieved as a linear combination of movement along both lateral axes.

[0137] The actuator assembly 2 can have other specific arrangements of actuation units 30, as Figure 5 shown. For example, strict symmetry is not required. Furthermore, instead of there being an up-pull actuation unit 30 and a down-pull actuation unit 30 on each side, there can be two up-pull actuation units 30 on each of two opposite sides (e.g. the first and third sides) and two down-pull actuation units 30 on the other two sides (e.g. the second and fourth sides).

[0138] Embodiment of actuator assembly

[0139] Figure 6 A perspective view of an actuator assembly 2 according to an embodiment of the disclosure is shown. In this embodiment, the actuator assembly 2 comprises eight actuation units 30a-30h, although it will be appreciated that at least some of the functionality of the actuator assembly (described below) can be implemented with more or fewer actuation units. Similarly to Figure 5 the actuator assembly shown in Figure 7 the actuation force F applied by each actuation unit 30 is schematically illustrated. Figure 6

[0140] Figure 6 ​The arrangement of actuation units 30 can for example be used in examples in which the movable part is movable relative to the support structure with three translational degrees of freedom (Tx, Ty, Tz) (see Figure 1E ) or with two or three rotational degrees of freedom (Rx, Ry or Rx, Ry, Rz) (see Figure 2 ).

[0141] It can be seen from Figure 8 that each actuation unit 30a-30h of the actuator assembly 2 is in some respects similar to the actuation unit 30 depicted in Figure 3A and Figure 3B . In particular, Figure 6 each actuation unit 30a-30h of the actuator assembly 2 depicted in Figure 3A comprises a respective body portion 31, an SMA element 34 connected between the body portion 31 and the support structure, a force-modifying element 32 (e.g. a force-modifying flexure) connected between the body portion and the support structure, and a coupling link 33 (e.g. a coupling flexure) connected between the body portion and the movable part. Each actuation unit is connected to the support structure at a distal end of the force-modifying flexure via a foot portion (such as the foot portion 36 shown in Figure 3A ). In addition, each actuation unit is connected to the support structure at a distal end of the SMA element (e.g. using a crimp such as the crimp 15 shown in Figure 3A ). Each actuation unit is also connected to the movable part via a distal end of the coupling link, in particular via the connection portion 21a, as described above in relation to Figure 3B and .

[0142] It is generally described herein that the force-modifying flexure 32 and the SMA element 34 are connected to the support structure 10, while the coupling link (e.g. the coupling flexure 33) is connected to the movable part 20. However, in some embodiments, some of the actuation units can be connected between the support structure and the movable part in the opposite direction. In other words, in at least some of the actuation units, the SMA element 34 and the force-modifying flexure 32 can be connected to the movable part 20, and the coupling link / flexure 34 can be connected to the support structure 10. For example, some or all of the first set of actuation units can be connected in the opposite direction and / or some or all of the second set of actuation units can be connected in the opposite direction.

[0143] As described above in relation to Figures 3A-3CIn more detail, the SMA element is configured to, upon actuation, apply an input force Fi to the body portion. The force-modifying element is in turn configured to modify the input force so as to generate an actuation force F through the coupling link. In other words, the force-modifying element is configured to amplify or reduce the input force / travel of the SMA element depending on the physical arrangement of the SMA element, the force-modifying element and the coupling link, which is described above with reference to Figures 3A-3C In more detail, the coupling link is configured to transmit the actuation force from the body portion to the movable portion so as to move the movable portion relative to the support structure.

[0144] Similarly to the actuator assembly shown in Figure 4 and Figure 5 , the actuator assembly 2 can have a square or rectangular (or more generally quadrilateral) footprint. In Figure 6 particular examples, the actuator assembly has a square footprint, where the four sides correspond to the four sides of the support structure. The four sides are arranged around a principal axis P extending through the actuator assembly, similar to the principal axis depicted in Figures 1A-1E and Figure 2 . It will be appreciated that in other examples, the actuator assembly can have a footprint of a different shape with a corresponding different number of sides. Furthermore, the sides in which the actuation units 30 are arranged need not correspond to the sides of the support structure 10 or the movable portion 20. In other words, the sides can be defined solely by the presence of the actuation units 30. Furthermore, in some other embodiments, the sides in which the actuation units 30 are arranged need not be parallel to the principal axis and / or need not all have the same extent along the principal axis. In general, the plurality of actuation units can be arranged in any suitable manner such that each actuation unit comprises an SMA element arranged along a first side of the actuator assembly and a coupling link arranged along a second side of the actuator assembly, wherein the second side is adjacent to the first side, and wherein the plurality of actuation units are arranged such that for each direction along each axis of a Cartesian coordinate system (+x, -x, +y, -y, +z, -z), there is at least one actuation force having a non-zero component along that direction.

[0145] As shown in Figure 6 , each actuation unit 30 extends along two adjacent sides of the actuator assembly. In particular, the SMA element of each actuation unit is arranged along a first side of the four sides, and its coupling link is arranged along a second side adjacent to the first side. In other words, each actuation unit is arranged such that it bends around a corner of the actuator assembly, such that the SMA element and the coupling link of each actuation unit 30 extend along adjacent sides of the actuator assembly. In relation to the input force and the actuation force of each actuation unit, this means that, in some examples, the input force applied by the SMA element of each actuation unit can be approximately perpendicular to the respective actuation force when the actuator assembly is viewed along the principal axis.

[0146] Each actuation unit extending along two adjacent sides of the actuator assembly can also be described based on the angular range of the actuation unit about the main axis. Specifically, when viewed along the main axis, the maximum angle subtendable by the actuation unit relative to the main axis is at least 90°, and can be between 90° and 180° (because in a square arrangement, the actuation units extending along two adjacent sides will subtend a maximum angle of 180° between the relative angles of the actuator assembly). The maximum angle subtendable by the actuation unit is determined between the farthest endpoint along the SMA element (farthest from the main body portion 31) and the farthest endpoint along the connecting link.

[0147] Now for reference Figure 7 It schematically depicts what can be generated by Figure 6 The actuating force F applied by the actuation units 30a-30h of the actuator assembly 2 shown. Figure 7 The perspective view corresponds to Figure 6 . Figure 7 In particular, it shows Figure 6 The actuation units are arranged such that for each direction along each axis of the Cartesian coordinate system (+x, -x, +y, -y, +z, -z), there exists at least one actuating force F with a non-zero component along that direction. The arrangement of the actuation units 30a-30h enables the movable part to move relative to the support structure with three translational degrees of freedom (e.g., independently along each of the x, y, and z axes) and three rotational degrees of freedom (e.g., independently about each of the x, y, and z axes), although, as will be understood, the movable part 20 may move with fewer degrees of freedom in certain examples due to the manner in which the controller 9 controls the actuation units and / or due to constraints such as the support arrangement 40.

[0148] More specifically, and considering each actuation force as a vector in a Cartesian coordinate system, Figure 7 The diagram shows that each actuating force has a component parallel to the x-axis or y-axis and a component parallel to the z-axis. In other words, assuming the main axis P extending through the actuator assembly is parallel to the z-axis, each actuating force has a first component perpendicular to the main axis and a second component parallel to the main axis. The component perpendicular to the main axis may be referred to herein as the lateral component, while the component parallel to the main axis may be referred to herein as the vertical component.

[0149] Figure 6 and Figure 7 The actuation units of the illustrated embodiment can be considered to be arranged in four pairs, wherein for each pair, the lateral component of the actuating force is in the same direction. In other words, for the eight actuation units depicted, there is one pair of actuation units that provides an actuating force having a component along each of the +x, -x, +y, and -y directions. In particular:

[0150] 30a and 30b are arranged in a first pair, as both units exert an actuation force with a component in the +x direction;

[0151] 30c and 30d are arranged in a second pair, as both units exert an actuation force with a component in the -x direction;

[0152] 30e and 30f are arranged in a third pair, as both units exert an actuation force with a component in the +y direction;

[0153] 30g and 30h are arranged in a fourth pair, as both units exert an actuation force with a component in the -y direction.

[0154] In addition to exerting an actuation force in the lateral direction (i.e. perpendicular to the primary axis), the actuation force F exerted by each actuation unit also has a vertical component parallel to the primary axis. In the illustrated embodiment, the first and second pairs of units 30a-30d exert an actuation force with a vertical component in the +z direction, while the third and fourth pairs of actuation units 30e-30h exert an actuation force with a vertical component in the -z direction. In other embodiments, as described in more detail below, different actuation units within a given pair of actuation units can have actuation forces with the same lateral component but opposite components along the primary axis / z-axis. Figures 6-8 In the particular embodiment illustrated, the first and second pairs of units 30a-30d exert an actuation force with a vertical component in the +z direction, while the third and fourth pairs of actuation units 30e-30h exert an actuation force with a vertical component in the -z direction. In other embodiments, as described in more detail below, different actuation units within a given pair of actuation units can have actuation forces with the same lateral component but opposite components along the primary axis / z-axis.

[0155] Figure 8 An alternative view of the actuator assembly illustrated in FIGS. 1-3 is depicted, and shows that the actuation units are arranged such that the SMA elements of any given pair of actuation units are arranged along the same one of the four sides of the actuator assembly. The SMA elements 34a, 34b of the first pair 30a, 30b are arranged along the same first side. Similarly, the SMA elements 34c and 34d of the second pair 30c and 30d are arranged along a second side, which in this embodiment is opposite the first side. The SMA elements 34e and 34f of the third pair 30e and 30f are arranged along a third side, which in this embodiment is adjacent to the first and second sides, while the SMA elements 34g and 34h of the fourth pair 30g and 30h are arranged along a fourth side, which in this embodiment is opposite the third side. In some embodiments, each pair of SMA elements can be substantially parallel to one another, although this is not required. Advantageously, the SMA elements of a given pair can be arranged parallel and adjacent to one another in order to minimize the space occupied by the SMA elements in the camera module, which is designed for use in a smartphone or other application where space is at a premium. Figure 6 Figure 7 In the particular embodiment illustrated, the first and second pairs of units 30a-30d exert an actuation force with a vertical component in the +z direction, while the third and fourth pairs of actuation units 30e-30h exert an actuation force with a vertical component in the -z direction. In other embodiments, as described in more detail below, different actuation units within a given pair of actuation units can have actuation forces with the same lateral component but opposite components along the primary axis / z-axis.

[0156] ​While for each pair of actuation units, the SMA elements are arranged along the same side of the actuator assembly, the coupling link 33a-33h of any given pair can be arranged on the opposite side of the actuator assembly, as can be seen in Figure 8 The arrangement of the actuation units in each pair is such that, upon actuation, the SMA elements arranged along the same side of the actuator assembly exert an input force towards the opposite end of the side, which input force generates a pair of actuation forces through the force-modifying element 32a-32h, which pair of actuation forces is transmitted along the opposite side of the actuator assembly through the coupling link. As mentioned above, the transverse components of each of the pair of actuation forces are in the same direction. In the particular embodiment shown, the components of the actuation forces parallel to the main axis are also in the same direction. In general, the pair of actuation forces can be parallel, although this is not essential. In other examples (see discussion below), the vertical components of the pair of actuation forces can be in opposite directions.

[0157] There is an angular overlap between each actuation unit in any given pair due to the SMA elements in the pair being arranged on the same side of the actuator assembly, when viewed along the main axis. In other words, the angular range of a first actuation unit in a pair of actuation units overlaps the angular range of a second actuation unit in the pair of actuation units.

[0158] In a square arrangement, such as in the example depicted in the accompanying drawings, the amount of overlap between a pair of actuation units (i.e. the angle subtended by the overlapping portions of a pair of actuation units) is 90° or less due to the square geometry. If the SMA elements in a pair of actuation units extend along the full length of the side on which they are arranged, then the overlap between the actuation units is exactly 90°. However, typically, the SMA elements extend along less than the full length of the side on which they are arranged, which means that the angle subtended by the overlapping portions of the SMA elements is less than 90° when viewed along the main axis.

[0159] In addition to the actuation units being angularly overlapped in pairs as described above, in some examples, each actuation unit also angularly overlaps at least one other actuation unit (in addition to the corresponding actuation unit in a pair) when viewed along the main axis. In other words, the angular range of any given actuation unit around the main axis overlaps the angular range of two or more other actuation units around the main axis, where one of the two or more other actuation units is paired with the given actuation unit.

[0160] Considering the example of a square arrangement in more detail Figures 6-8In the depicted embodiment, the eight actuation units of the actuator assembly can be divided into two groups. The first group is a "top" group and includes actuation units that provide actuation forces having a component in the +z direction, in this embodiment including the first and second pairs of actuation units 30a-30d. The second group is a "bottom" group and includes actuation units that provide actuation forces having a component in the -z direction, in this embodiment including the third and fourth pairs of actuation units 30e-30h.

[0161] Referring to Figure 13 , an alternative perspective view of the actuator assembly of Figures 6-8 is provided. In this particular view, only the first group of actuation units (i.e., 30a-30d) with the support structure 10 and movable portion 20 are shown. As shown in this figure, the actuation units of the first group can be arranged along one or more surfaces of the support structure of the actuator assembly that generally face in the +z direction. For example, the one or more surfaces of the support structure can be planar and the normal to each of these surfaces can generally point in the +z direction, or can at least have a greater component in the +z direction than in any transverse (x or y) direction. Similarly, although not shown in the figure, it will be appreciated that the actuation units of the second group can be arranged along one or more surfaces of the support structure of the actuator assembly that generally face in the -z direction. For example, the one or more surfaces can be planar and the normal to each of these surfaces can generally point in the -z direction, or can at least have a greater component in the -z direction than in any transverse (x or y) direction. In this way, the actuation units that provide actuation forces having a component in the +z direction are arranged on a top side of the actuator assembly (i.e., as shown at the top of the actuator assembly), where the top side also generally faces in the +z direction, while the actuation units that provide actuation forces having a component in the -z direction are arranged on a bottom side of the actuator assembly (not shown in Figure 13 ). Figure 13 It will be appreciated that the bottom side of the actuator assembly can look identical to the top side, subject to a 180 degree rotation of the actuator assembly about the x or y axis and a 90 degree rotation about the z axis. More generally, the one or more surfaces along which the first group of actuation units are arranged can substantially correspond to the one or more surfaces along which the second group of actuation units are arranged.

[0162] Referring now to Figure 9 , a perspective view of an alternative arrangement of actuation units 30a-30h in the actuator assembly 2 is depicted. As with the above-referenced Figures 6-8As described for the embodiment, the eight actuation units are divided into four pairs, with each pair comprising actuation units that all provide an actuation force F having a component in the same lateral direction (+x, -x, +y or -y). The actuation force provided by each actuation unit in this arrangement is in the same direction as the actuation force provided by the other actuation units in the same pair. In other words, the actuation force provided by each actuation unit in a pair is in the same direction as the actuation force provided by the other actuation units in the same pair. Figure 10 is equivalent to Figure 7 but corresponds to an alternative embodiment of Figure 9 In this alternative embodiment, the actuation units are arranged such that:

[0163] O 30a and 30b are arranged in a first pair, as both units exert an actuation force with a component in the +x direction;

[0164] O 30c and 30d are arranged in a second pair, as both units exert an actuation force with a component in the -x direction;

[0165] O 30e and 30f are arranged in a third pair, as both units exert an actuation force with a component in the +y direction;

[0166] O 30g and 30h are arranged in a fourth pair, as both units exert an actuation force with a component in the -y direction.

[0167] However, in contrast to the aforementioned embodiment in which the pairs of actuation units also provide actuation forces with the same vertical component, in this embodiment the pairs of actuation units provide actuation forces with opposite vertical components. Taking the first pair as an example, actuation unit 30a provides an actuation force with a component in the +z direction, while actuation unit 30b provides an actuation force with a component in the -z direction. More generally, each pair of actuation units has a first actuation unit arranged to exert an actuation force with a component along the +z direction and a second actuation unit arranged to exert an actuation force with a component along the -z direction. In more detail, each first actuation unit in each pair of first actuation units is arranged substantially along a top side of the actuator assembly (i.e. along one or more surfaces facing substantially in the +z direction). Each second actuation unit in each pair of second actuation units is arranged substantially along a bottom side of the actuator assembly (i.e. along one or more surfaces facing substantially in the -z direction). This arrangement is similar to the arrangement described with respect to Figures 6 to 8 as the actuation units providing actuation forces with a component in the +z direction are arranged on a top side of the actuator assembly, where the top side also faces substantially in the +z direction, while the actuation units providing actuation forces with a component in the -z direction are arranged on a bottom side of the actuator assembly, where the bottom side also faces substantially in the -z direction.

[0168] From Figure 6 and Figure 8It can be seen that each pair of actuation units (30a and 30b, 30c and 30d, 30e and 30f, 30g and 30h) has SMA elements 34a-34h arranged along the same side of the actuator assembly, while the coupling link in any given pair is arranged along the opposite side. As with the previous embodiments, the arrangement of the actuation units in each pair is such that, upon actuation, the SMA elements arranged along the same side of the actuator assembly exert an input force towards the opposite end of that side, which generates a pair of actuation forces through the force-modifying elements 32a-32h, which are transmitted along the opposite side of the actuator assembly through the coupling link.

[0169] Reference is now made to Figure 12 , which shows a schematic diagram of an alternative arrangement of actuation units. In this particular embodiment, as with the other embodiments, the actuation units are arranged in pairs, with the actuation units in each pair providing actuation forces having a transverse component in the same direction. The SMA elements in each pair are arranged along the same side of the actuator assembly in the same manner as in the other embodiments described above, while the coupling link in each pair is also arranged on the same side (unlike in the embodiments described above). For any given pair of actuation units, the side along which the coupling link is arranged is adjacent to the side along which the SMA elements are arranged. Thus, in these embodiments, the SMA elements of the actuation units of any given pair exert an input force towards the same longitudinal end of the side along which the SMA elements are arranged, which generates a pair of actuation forces through the respective force-modifying elements, which are transmitted along the adjacent side of the actuator assembly through the coupling link. The pair of actuation forces have the same transverse component and opposite components along the principal axis.

[0170] Other variants

[0171] It will be appreciated that there can be many other variations of the examples described above.

[0172] For example, the actuator assembly can comprise different types of actuation units than described above. Examples of such actuation units include folded SMA wire arrangements as disclosed in WO 2021 / 111131 Al, V-shaped SMA wires with deformable connectors as disclosed in WO 2013 / 121225 Al, scissor-type jacking devices as disclosed in WO 2021 / 156458 Al, two-stage devices as disclosed in WO 2021 / 111181 Al, or simply SMA wires connected between the support structure 10 and the movable portion 20. The documents referred to in the preceding sentence are each incorporated herein by reference. The actuator assembly can have any number of different types of actuation units, and can have any suitable number of actuation units of each type.

[0173] SMA

[0174] The above-described SMA actuator assembly includes at least one SMA element. The term“shape memory alloy (SMA) element” can refer to any element that contains SMA. The SMA element can be described as an SMA wire. The SMA element can have any shape suitable for the purposes described herein. The SMA element can be elongate and can have a circular cross-section or any other shaped cross-section. The cross-section can vary along the length of the SMA element. The SMA element can have a relatively complex shape, such as a helical spring shape. It is also possible that the length (however defined) of the SMA element can be similar to one or more of the other dimensions of the SMA element. The SMA element can be sheet-like, and such a sheet can be planar or non-planar. The SMA element can be pliant, or in other words, the SMA element can be flexible. In some examples, the SMA element can only exert a tensile force urging two components together when connected in a straight line between the two components. In other examples, the SMA element can be bent around a component, and the SMA element can exert a force to the component when the SMA element tends to straighten under tension. The SMA element can be beam-like or rigid and be able to exert different forces (e.g. non-tensile forces) to the element. The SMA element can or can not include non-SMA materials and / or components. For example, the SMA element can include a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term“SMA element” can refer to any configuration of SMA material that acts as a single actuation element, e.g. that can be independently controlled to produce a force acting on the element. For example, the SMA element can include two or more portions of SMA material arranged mechanically in parallel and / or in series. In some arrangements, the SMA element can be part of a larger SMA element. Such a larger SMA element can include two or more portions that are individually controllable, thereby forming two or more SMA elements. The SMA element can include an SMA wire, an SMA foil, an SMA film, or any other configuration of SMA material. The SMA element can be manufactured using any suitable method, e.g. by a method involving drawing, rolling, deposition, sintering, or powder melting. The SMA element can exhibit any shape memory effect, e.g. a thermal shape memory effect or a magnetic shape memory effect, and can be controlled in any suitable way (e.g. by Joule heating, another heating technique, or by applying a magnetic field).

Claims

1. An actuator assembly, characterized in that, The actuator assembly includes: Part One; The second part is arranged to be movable relative to the first part; A plurality of actuation units, each actuation unit being configured to apply an actuating force to one of the first portion and the second portion, the first portion and the second portion being capable of moving the second portion relative to the first portion, wherein at least one of the actuation units includes: Main body; An SMA element, the SMA element being connected between the body portion and another of the first and second portions, and configured to apply an input force to the body portion upon actuation; and A force-modifying element, connected between the main body portion and the other of the first and second portions, and configured to modify the input force to generate an actuating force; and A connecting link connecting the main body portion to one of the first and second portions, wherein the connecting link is configured to transmit an actuating force from the main body portion to one of the first and second portions, and wherein the connecting link is deformable in a direction perpendicular to the actuating force. Each actuation unit includes an SMA element arranged along a first side of the actuator assembly and a connecting rod arranged along a second side of the actuator assembly, wherein the second side is adjacent to the first side; and The plurality of actuation units are arranged such that for each direction along each axis of the Cartesian coordinate system (+x, -x, +y, -y, +z, -z), there exists at least one actuation force having a non-zero component along that direction.

2. The actuator assembly according to claim 1, characterized in that, The actuator assembly includes a main axis extending through the actuator assembly, and wherein the first side and the second side of the actuator assembly are arranged around the main axis.

3. The actuator assembly according to claim 2, characterized in that, The actuator assembly includes four sides arranged around the main axis.

4. The actuator assembly according to claim 3, characterized in that, The adjacent sides are perpendicular, and therefore when viewed along the main axis, the four sides form a quadrilateral shape.

5. The actuator assembly according to claim 2, characterized in that, The input force applied by each SMA element of each actuation unit is in a direction substantially perpendicular to the main axis, and wherein the actuation force of each actuation unit has a first component parallel to the main axis and a second component perpendicular to the main axis.

6. The actuator assembly according to any one of claims 2 to 5, characterized in that, When viewed along the main axis, the input force of each actuation unit is in a direction approximately perpendicular to the corresponding actuation force.

7. The actuator assembly according to any one of claims 2-5, characterized in that, The actuator assembly includes eight actuation units.

8. The actuator assembly according to any one of claims 2-5, characterized in that, The actuation units are arranged in pairs, and for each pair of actuation units, the SMA elements are arranged along the same side of the actuator assembly.

9. The actuator assembly according to claim 8, characterized in that, For each pair of actuation units, the SMA element is configured to apply an input force toward the opposite longitudinal end of the side along which the SMA element is arranged when actuated.

10. The actuator assembly according to claim 8, characterized in that, For each pair of actuation units, the SMA element is configured to apply an input force toward the same longitudinal end along the side along which the SMA element is arranged when actuated.

11. The actuator assembly according to claim 8, characterized in that, For each pair of actuation units, the connecting rods are arranged along opposite sides of the actuator assembly.

12. The actuator assembly according to claim 11, characterized in that, For each pair of actuation units, the connecting links are configured to transmit generally parallel actuation forces to one of the first and second portions.

13. The actuator assembly according to claim 10, characterized in that, For each pair of actuation units, the connecting rods are arranged along the same side of the actuator assembly.

14. The actuator assembly according to any one of claims 9-13, characterized in that: The first pair of actuation units are each arranged to apply an actuating force having a component in a first direction along a first transverse axis, wherein the first transverse axis is perpendicular to the main axis; The second pair of actuation units are each arranged to apply an actuating force along the first transverse axis having a component along a second direction opposite to the first direction; The third pair of actuation units are each arranged to apply an actuating force having a component in the third direction along the second transverse axis, wherein the second transverse axis is perpendicular to the main axis and the first transverse axis; and The fourth pair of actuation units are each arranged to apply an actuating force along the second transverse axis, having a component along a fourth direction opposite to the third direction.

15. The actuator assembly according to claim 14, characterized in that: The first pair of actuation units and the second pair of actuation units are each arranged to apply an actuating force having a component along the fifth direction along the main axis; The third pair of actuating units and the fourth pair of actuating units are each arranged to apply an actuating force along the main axis having a component along a sixth direction opposite to the fifth direction.

16. The actuator assembly according to claim 14, characterized in that, Each pair of actuation units includes a first actuation unit and a second actuation unit, wherein: The first actuating unit in each pair of actuating units is arranged to apply an actuating force having a component along the fifth direction along the main axis; and The second actuation unit in each pair of actuation units is arranged to apply an actuating force along the main axis having a component along a sixth direction opposite to the fifth direction.

17. The actuator assembly according to claim 15, characterized in that: The main body portions of the first pair of actuation units and the second pair of actuation units, the SMA element and the force modification element are arranged along one or more surfaces, which are generally oriented in the fifth direction along the main axis; and The main body portions of the third pair of actuation units and the fourth pair of actuation units, the SMA element and the force modification element are arranged along one or more surfaces, which are generally oriented in the sixth direction along the main axis.

18. The actuator assembly according to claim 16, characterized in that: The main body portion, the SMA element, and the force modification element of each of the pairs of first actuation units are arranged along one or more surfaces, which are generally oriented in the fifth direction along the main axis; and The main body portion, the SMA element, and the force modification element of each of the pairs of second actuation units are arranged along one or more surfaces, which are generally oriented in the sixth direction along the main axis.

19. The actuator assembly according to any one of claims 2-5, 9-13, and 15-18, characterized in that, Each actuation unit has an angular range of greater than 90° around the main axis.

20. The actuator assembly according to claim 8, characterized in that, Each actuation unit has an angular range of greater than 90° around the main axis.

21. The actuator assembly according to claim 20, characterized in that, When viewed along the main axis, a portion of the first actuation unit and a portion of the second actuation unit in each pair of actuation units overlap with each other.

22. The actuator assembly according to claim 21, characterized in that, The overlapping portion of the first and second actuation units in each pair of actuation units has an angle range of less than 90° around the main axis.

23. The actuator assembly according to any one of claims 20 to 22, characterized in that, The angular range of each actuation unit about the main axis overlaps with the angular range of two or more other actuation units about the main axis.

24. The actuator assembly according to any one of claims 2-5, 9-13, 15-18, and 20-22, characterized in that, The SMA element and the connecting link of any given actuation unit are arranged in a plane having a normal that is inclined at an angle relative to the main axis.

25. A camera assembly, characterized in that, The camera assembly includes: The actuator assembly according to any one of claims 1 to 24; One or more lenses, said one or more lenses being included in one of the first and second portions of the actuator assembly; and An image sensor, the image sensor being included in another of the first and second portions of the actuator assembly; The actuator assembly is configured to move the one or more lenses and the image sensor relative to each other in three translational degrees of freedom.

26. A camera assembly, characterized in that, The camera assembly includes: The actuator assembly according to any one of claims 1 to 24; and A support structure, the support structure including one of the first portion and the second portion of the actuator assembly; Module, the module being included in another of the first and second portions of the actuator assembly, wherein The module includes one or more lenses and an image sensor; The actuator assembly is configured to cause the module to rotate relative to the support structure in two or more rotational degrees of freedom.

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