Control device and control method

Abstract

To provide a control device for controlling the driving of an actuator in accordance with displacement variations caused by gravitational accelerations in the actuator using a shape-memory alloy.SOLUTION: A control device is provided that controls the driving of an actuator by deforming a shape-memory alloy connected to a movable part of the actuator and that comprises: a target signal setting unit for setting a target signal in accordance with a target displacement of the actuator; a compensation calculation unit for outputting a compensation signal on the basis of predetermined compensation information; a control unit for generating an operation signal in accordance with the target signal and the compensation signal; and a driving signal output unit for outputting a driving signal in accordance with the operation signal to the actuator. The compensation information includes attitude information of the actuator.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a control device and a control method. [Background technology]

[0002] 2. Description of the Related Art Conventionally, with respect to a control device for an actuator that is driven by the deformation of a shape memory alloy, it is known that the response is improved by applying a bias current (for example, Patent Document 1). [Prior art document] [Patent documents] [Patent Document 1] Patent No. 4857550 Summary of the Invention [Problem to be solved by the invention]

[0003] A control device is provided that controls the drive of an actuator using a shape memory alloy in response to a displacement fluctuation due to gravitational acceleration in the actuator. [Means for solving the problem]

[0004] In a first aspect of the present invention, a control device is provided that controls the driving of an actuator by deforming a shape memory alloy connected to a movable part of the actuator, the control device comprising a target signal setting unit that sets a target signal corresponding to a target displacement of the actuator, a compensation calculation unit that outputs a compensation signal based on predetermined compensation information, a control unit that generates an operation signal corresponding to the target signal and the compensation signal, and a drive signal output unit that outputs a drive signal corresponding to the operation signal to the actuator, wherein the compensation information includes posture information of the actuator.

[0005] In a second aspect of the present invention, there is provided a control method for controlling the driving of an actuator by deforming a shape memory alloy connected to a movable part of the actuator, the control method comprising the steps of setting a target signal corresponding to a target displacement of the actuator, outputting a compensation signal based on predetermined compensation information, outputting an operation signal based on the target signal and the compensation signal, and outputting a drive signal to the actuator based on the operation signal, wherein the compensation information includes posture information of the actuator.

[0006] The above summary of the invention does not list all of the features of the present invention. Also, subcombinations of these features may also be inventions. [Brief description of the drawings]

[0007] [Figure 1A] 1 shows an example of the configuration of a control device 100. [Figure 1B] 2 shows an example of an operation flowchart of the control device 100. [Figure 2A] An example of the configuration of a bias type actuator 200 is shown. [Figure 2B] An example of the configuration of a push-pull type actuator 200 is shown. [Figure 2C] An example of the configuration of a push-pull type actuator 200 is shown. [Figure 2D] An example of the configuration of a bias type actuator 200 is shown. [Figure 2E] An example of the configuration of a push-pull type actuator 200 is shown. [Figure 2F] An example of the configuration of a push-pull type actuator 200 is shown. [Figure 2G] An example of the configuration of a push-pull type actuator 200 is shown. [Figure 3A] 1 shows an example of the configuration of a control device 100. [Figure 3B] 1 shows an example of the configuration of a control device 100. [Figure 4]1 is a diagram for explaining the deformation characteristics of a shape memory alloy 220. FIG. [Figure 5A] 1 shows an example of the configuration of a control device 100 that compensates for characteristic fluctuations due to hysteresis. [Figure 5B] An example of hysteresis of the shape memory alloy 220 is shown. [Figure 5C] 4 shows the deformation characteristics of the shape memory alloy 220 due to the first amplitude vibration. [Figure 5D] 4 shows the deformation characteristics of the shape memory alloy 220 due to the second amplitude vibration. [Figure 5E] 10 is a diagram for explaining the operation of the hysteresis compensation section 60. FIG. [Figure 6A] 11 is a diagram for explaining an example of a method for setting a drive current Id. FIG. [Figure 6B] 11 is a diagram for explaining an example of a method for setting a drive current Id. FIG. [Figure 6C] 11 is a diagram for explaining an example of a method for setting a drive current Id. FIG. [Figure 7A] 1 shows an example of the configuration of a control device 100 that compensates for characteristic variations according to other-axis displacements. [Figure 7B] An example of a shape memory alloy 220 in which a displacement point Ed is displaced in the driving direction and in other axial directions is shown. [Figure 8] 1 shows an example of the configuration of a control device 100 that compensates for characteristic variations according to temperature. [Figure 9] 1 shows an example of the configuration of a control device 100 that compensates for characteristic variations according to the attitude of an actuator 200. [Figure 10A] 11 is a diagram for explaining a method for determining the compensation amount of the drive signal Sdr. FIG. [Figure 10B] An example of a method for determining the compensation amount will be described. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0009] 1A shows an example of the configuration of the control device 100. The control device 100 includes a target signal setting unit 10, a compensation calculation unit 20, a displacement signal output unit 30, a control unit 40, a drive signal output unit 50, and a bias signal generation unit 52. The control device 100 of this example controls the drive of the actuator 200 by deforming a shape memory alloy 220 connected to a movable part 210 of the actuator 200. The movable part 210 and the shape memory alloy 220 will be described later.

[0010] The target signal setting unit 10 sets a target signal Sg according to target displacement information of the actuator 200. The target signal Sg is a signal for driving the actuator 200 to a target displacement indicated by the target displacement information. The target signal setting unit 10 may set a plurality of target signals Sg. For example, if the actuator 200 has a plurality of shape memory alloys 220, a target signal Sg may be set for each of the plurality of shape memory alloys 220. For example, if the actuator has a plurality of driving directions, a target signal Sg may be set for each of the driving directions.

[0011] The compensation calculation unit 20 outputs a compensation signal Sc based on predetermined compensation information Ic. The compensation signal Sc includes a compensation amount for compensating for characteristic variations of the shape memory alloy 220. For example, the characteristic variations of the shape memory alloy 220 refer to variations in the deformation characteristics of the shape memory alloy 220 in response to the drive signal Sdr depending on the operating state, operating environment, operating history, etc. of the actuator 200. The control device 100 outputs an increased or decreased drive signal Sdr to the actuator 200 depending on the compensation signal Sc.

[0012] The compensation information Ic includes information necessary to compensate for the characteristic fluctuation of the shape memory alloy 220. For example, the compensation information Ic includes information related to the deformation characteristics of the shape memory alloy 220, such as hysteresis information of the shape memory alloy 220. In one example, the hysteresis information includes history information related to the expansion and contraction of the shape memory alloy 220. The compensation information Ic may also include displacement information, temperature information, or posture information of the movable part 210. Specific examples of the compensation information Ic will be described later.

[0013] The drive signal Sdr is a signal for applying a predetermined drive current Id or drive voltage Vd to the shape memory alloy 220. The drive signal Sdr includes a bias signal Sb for setting the temperature of the shape memory alloy 220 in a transformation temperature region. The transformation temperature region will be described later. For example, when supplying the drive current Id in response to the drive signal Sdr, the drive signal output unit 50 supplies the bias current Ib to the shape memory alloy 220 as the bias signal Sb.

[0014] The displacement signal output unit 30 outputs a displacement signal Sd based on current displacement information of the movable part 210. The displacement signal Sd includes information on the displacement of the movable part 210 from a predetermined reference position. The current displacement information includes information such as the coordinates of the current position of the movable part 210. In one example, the displacement signal output unit 30 acquires an output from a position sensor for detecting the position of the movable part 210 as the current displacement information, and outputs a displacement signal Sd corresponding to a change in the output of the position sensor to the control unit 40. In another example, a position sensor may be provided outside the control device 100 as the position detection unit 230. The position detection unit 230 will be described later.

[0015] The current displacement information may be information corresponding to the resistance change of the shape memory alloy 220. In this case, the displacement signal output section 30 outputs a displacement signal Sd corresponding to the resistance change of the shape memory alloy 220 to the control section 40. The displacement signal Sd is calculated by obtaining the length of the shape memory alloy 220 from the resistance change of the shape memory alloy 220. In the control device 100 of this example, the position accuracy and responsiveness of the movable section 210 can be improved by compensating for and controlling the characteristic fluctuation of the shape memory alloy 220.

[0016] The control unit 40 outputs an operation signal Sm to control the drive signal Sdr supplied to the actuator 200. The control unit 40 of this example outputs the operation signal Sm according to the target signal Sg, the displacement signal Sd, and the compensation signal Sc. That is, the control unit 40 of this example performs feedback control using the displacement signal Sd from the actuator 200, and therefore functions as a closed-loop control circuit. The operation signal Sm is a signal that indicates the amount of operation of the shape memory alloy 220.

[0017] The drive signal output section 50 drives the actuator 200 by deforming the shape memory alloy 220 in response to the drive signal Sdr. The drive signal output section 50 outputs the drive signal Sdr to the actuator 200 in response to the operation signal Sm, the compensation signal Sc, and the bias signal Sb. For example, the drive signal output section 50 increases or decreases the drive signal Sdr based on the bias signal Sb in response to the operation signal Sm. When the actuator 200 has a plurality of shape memory alloys 220, the drive signal output section 50 may output the drive signal Sdr to each shape memory alloy 220. In another example, the drive signal output section 50 may change the bias signal Sb to be supplied to each shape memory alloy 220.

[0018] The bias signal generating unit 52 generates a bias signal Sb. Even if the actuator 200 has a plurality of shape memory alloys 220, the bias signal generating unit 52 may generate the same bias signal Sb for the plurality of shape memory alloys 220. In this case, the control device 100 compensates for each of the plurality of shape memory alloys 220 with a different compensation amount. For example, the bias signal generating unit 52 sets the bias signal Sb so as to improve the responsiveness of the shape memory alloys 220. The bias signal generating unit 52 may generate different bias signals Sb for the plurality of shape memory alloys 220.

[0019] The control device 100 of this embodiment uses closed-loop control, which uses the displacement signal output unit 30 to feed back information on the current position of the controlled object and control the difference from the target position to converge to zero. However, the control device 100 may use open-loop control, which controls the controlled object with an operation amount according to the target position information, without using the displacement signal output unit 30. In the case of open-loop control, the control unit 40 outputs an operation signal Sm based on the target signal Sg and the compensation signal Sc.

[0020] 1B shows an example of an operation flowchart of the control device 100. In step S10, a target signal Sg is set based on target displacement information of the actuator 200. In step S12, a compensation signal Sc is output based on predetermined compensation information Ic. In step S14, a displacement signal Sd is output based on current displacement information. Note that the order of steps S10 to S14 is not limited to this example and may be changed.

[0021] In step S16, the operation signal Sm is outputted. In step S18, based on the operation signal Sm, the drive signal Sdr is outputted to the actuator 200. Note that steps S10 to S18 may be repeatedly executed.

[0022] 2A to 2G show an outline of the configuration of the actuator 200. The actuator 200 of this example is an SMA actuator that is driven by deformation of a shape memory alloy (SMA). The actuator 200 includes a movable part 210 and a shape memory alloy 220. The actuator 200 may further include a bias member 225. That is, the actuator 200 operates the movable part 210 by the thrust generated by the shape memory alloy 220.

[0023] The position of the movable part 210 is displaced by the thrust of the shape memory alloy 220. For example, the movable part 210 is a lens provided in an imaging device and refracts light incident on the imaging device. The movable part 210 is displaced in a predetermined driving direction. For example, when the actuator 200 is mounted on an imaging device, the displacement of the movable part 210 realizes an autofocus function or an image stabilization function.

[0024] The shape memory alloy 220 is connected to the movable part 210. The shape memory alloy 220 has a wire shape and is deformed by heating or heat dissipation. The heating and heat dissipation of the shape memory alloy 220 are realized by controlling the current flowing through the shape memory alloy 220 or the voltage applied to the shape memory alloy 220. In one example, the shape memory alloy 220 contracts by heating and expands by heat dissipation. For example, the shape memory alloy 220 is formed of NiTi, and contracts or expands by changing its crystal structure between the martensite phase (M) and the austenite phase (A).

[0025] The bias member 225 is connected to the movable part 210 and changes the position of the movable part 210 in response to contraction and expansion of the shape memory alloy 220. For example, the bias member 225 displaces the movable part 210 in the direction of a thrust force generated by the shape memory alloy 220 against the movable part 210 when the bias member 225 contracts or expands.

[0026] In this example, the movable part 210 provided in the imaging device is adjusted by driving the actuator 200. However, the actuator 200 may be applied to other applications as long as the driving is controlled by the shape memory alloy 220.

[0027] FIG. 2A shows an example of the configuration of a bias type actuator 200. The actuator 200 of this example includes a movable part 210, one shape memory alloy 220, and one bias member 225. The shape memory alloy 220 is provided extending in a predetermined driving direction (e.g., the Y-axis direction) so that the thrust of the shape memory alloy 220 balances with the spring thrust of the bias member 225. The thrust of the shape memory alloy 220 is a thrust generated in the shape memory alloy 220 in response to the drive signal Sdr. The movable part 210 is displaced in a predetermined driving direction (e.g., the Y-axis direction) by the thrust of the shape memory alloy 220 and the spring thrust.

[0028] For example, when the control device 100 starts to energize the shape memory alloy 220, it contracts the shape memory alloy 220 and displaces the movable part 210 in the direction in which the bias member 225 extends. On the other hand, when the control device 100 stops energizing the shape memory alloy 220, it expands the shape memory alloy 220 and displaces the movable part 210 in the direction in which the bias member 225 contracts.

[0029] One end point of the shape memory alloy 220 is a fixed point Ef, and the other end point is a displacement point Ed. The fixed point Ef is fixed at a predetermined position regardless of the displacement of the movable part 210. The displacement point Ed is a point connected to the movable part 210, and moves according to the displacement of the movable part 210. Similarly, the bias member 225 has one end point which is a fixed point Ef, and the other end point which is a displacement point Ed. The bias member 225 is connected to the movable part 210 at the displacement point Ed.

[0030] 2B shows an example of the configuration of a push-pull type actuator 200. A plurality of shape memory alloys 220 are connected to a movable part 210 in a push-pull arrangement. In the push-pull type actuator 200, the thrust of the plurality of shape memory alloys 220 is balanced to operate. The actuator 200 of this example includes a movable part 210 and two pieces of shape memory alloys 220. The plurality of shape memory alloys 220 are each connected to the movable part 210 at a displacement point Ed.

[0031] The shape memory alloy 220a and the shape memory alloy 220b are provided extending in a predetermined driving direction (for example, the Y-axis direction) so as to balance the thrusts of the shape memory alloys 220. The movable part 210 is balanced by the two shape memory alloys 220 and displaced in a predetermined driving direction (for example, the Y-axis direction).

[0032] The shape memory alloy 220a is provided in a pair with the shape memory alloy 220b. The drive signal output unit 50 may output a drive signal Sdr compensated for with different compensation amounts to the shape memory alloy 220a and the shape memory alloy 220b. For example, the shape memory alloy 220a and the shape memory alloy 220b may be compensated for characteristic fluctuations with a compensation amount according to hysteresis or the attitude of the actuator 200.

[0033] 2C shows an example of the configuration of a push-pull type actuator 200. The actuator 200 of this example includes a movable part 210, two shape memory alloys 220, and two bias members 225. The shape memory alloys 220 and the bias members 225 are each connected to the movable part 210 at a displacement point Ed. The shape memory alloys 220a and the bias members 225a are provided so that the thrusts of the shape memory alloys 220b and the bias members 225b are balanced with each other in a predetermined driving direction (for example, the Y-axis direction).

[0034] FIG. 2D shows an example of the configuration of the actuator 200, which is a bias type. The actuator 200 of this example includes a movable part 210, two shape memory alloys 220, and two bias members 225. The shape memory alloys 220 and the bias members 225 are each connected to the movable part 210 at a displacement point Ed. The shape memory alloys 220a and the bias members 225a are provided so that the thrust of the shape memory alloys 220 and the spring thrust are balanced in the Y-axis direction. Similarly, the shape memory alloys 220b and the bias members 225b are provided so that the thrust of the shape memory alloys 220 and the spring thrust are balanced in the X-axis direction. The actuator 200 of this example can displace the movable part 210 in two axial directions.

[0035] 2E shows an example of the configuration of a push-pull type actuator 200. The actuator 200 of this example includes a movable part 210 and four shape memory alloys 220a to 220d. The four shape memory alloys 220a to 220d are each connected to the movable part 210 at a displacement point Ed.

[0036] The shape memory alloy 220a and the shape memory alloy 220b are provided extending in a predetermined driving direction (for example, the Y-axis direction) so that the thrusts of the shape memory alloy 220 balance each other. Similarly, the shape memory alloy 220c and the shape memory alloy 220d are provided extending in a predetermined driving direction (for example, the X-axis direction) so that the thrusts of the shape memory alloy 220 balance each other. The actuator 200 of this example can displace the movable part 210 in two axial directions.

[0037] 2F shows an example of the configuration of a push-pull type actuator 200. The actuator 200 of this example includes a movable part 210 and four shape memory alloys 220a to 220d. The four shape memory alloys 220a to 220d are each connected to the movable part 210 at a displacement point Ed. The four shape memory alloys 220a to 220d are provided extending obliquely with respect to the driving direction of the movable part 210 (for example, the X-axis direction and the Y-axis direction).

[0038] 2G shows an example of the configuration of a push-pull type actuator 200. The actuator 200 of this example includes a movable part 210, four shape memory alloys 220, and four bias members 225. The four shape memory alloys 220 and the four bias members 225 are each connected to the movable part 210 at a displacement point Ed.

[0039] The shape memory alloy 220a and the bias member 225a are provided so that the thrust of the shape memory alloy 220b and the bias member 225b is balanced in the Y-axis direction. Similarly, the shape memory alloy 220c and the bias member 225c are provided so that the thrust of the shape memory alloy 220d and the bias member 225d is balanced in the X-axis direction.

[0040] Fig. 3A shows an example of the configuration of the control device 100. The control device 100 of this example differs from the control device 100 of Fig. 1A in that the drive signal output section 50 has a plurality of channels.

[0041] The drive signal output unit 50 has a plurality of channels, and outputs the drive signal Sdr respectively. In this way, when the actuator 200 has a plurality of shape memory alloys 220, different drive signals Sdr can be output to the respective shape memory alloys 220. For example, the drive signal output unit 50 has a plurality of channels according to the number of the shape memory alloys 220, and outputs the drive signal Sdr according to the deformation characteristics of each of the shape memory alloys 220. For example, when each of the plurality of shape memory alloys 220 shows different deformation characteristics, the drive signal output unit 50 increases or decreases the bias signal Sb by an appropriate operation amount according to the deformation characteristics. It is possible to prevent the actuator 200 from being driven in an unintended direction.

[0042] In this example, the control device 100 has a drive signal output section 50 that has multiple channels, so that even if the actuator 200 has multiple shape memory alloys 220 as shown in Figures 2B to 2G, it can output a drive signal Sdr according to each deformation characteristic.

[0043] Fig. 3B shows an example of the configuration of the control device 100. The control device 100 of this example will be described for the case where the movable part 210 is moved in two axial directions. In this example, differences from Fig. 3A will be particularly described.

[0044] The control device 100 includes a plurality of target signal setting units 10, compensation calculation units 20, displacement signal output units 30, control units 40, drive signal output units 50, and bias signal generation units 52. The control device 100 of this example includes two of each of the components corresponding to a first axis (e.g., X-axis) and a second axis (e.g., Y-axis).

[0045] The target signal setting unit 10a sets a target signal Sg according to target displacement information corresponding to a target displacement in the first axial direction, while the target signal setting unit 10b sets a target signal Sg according to target displacement information corresponding to a target displacement in the second axial direction.

[0046] The displacement signal output unit 30a acquires current displacement information of the shape memory alloy 220 corresponding to the current displacement in the first axial direction, while the displacement signal output unit 30b acquires current displacement information of the shape memory alloy 220 corresponding to the current displacement in the second axial direction.

[0047] As a result, the control device 100 can output a drive signal Sdr to the shape memory alloy 220 for moving the movable part 210 in the first axial direction and the shape memory alloy 220 for moving the movable part 210 in the second axial direction based on different target signals Sg, displacement signals Sd, compensation signals Sc and bias signals Sb.

[0048] 4 is a diagram for explaining the deformation characteristics of the shape memory alloy 220. The shape memory alloy 220 has a martensite phase and an austenite phase, and a transformation temperature range therebetween. The shape memory alloy 220 has a property of recovering the memorized shape when heated at a temperature equal to or higher than the reverse transformation finish temperature, even if it is plastically deformed by an external force at a temperature equal to or lower than the transformation start temperature (i.e., the martensite phase).

[0049] For example, in the transformation temperature region, the shape memory alloy 220 contracts when heated and expands when heat is released. By setting the bias signal Sb so that the temperature of the shape memory alloy 220 falls within the transformation temperature region, the responsiveness of the shape memory alloy 220 to heating and heat release is improved. The responsiveness refers to the speed from when the drive signal Sdr is supplied to the shape memory alloy 220 to when the movable part 210 starts to displace. The control device 100 may be set to a temperature that shows excellent responsiveness even within the transformation temperature region. By eliminating excessive tension or slackness of the shape memory alloy 220, the responsiveness of the movable part 210 can be well controlled.

[0050] 5A shows an example of the configuration of the control device 100 that compensates for the characteristic fluctuation according to the hysteresis. The control device 100 of this example includes a hysteresis compensation unit 60. The compensation information Ic includes the hysteresis information of the shape memory alloy 220.

[0051] The hysteresis compensation unit 60 outputs a compensation signal Sc for compensating for the hysteresis of the shape memory alloy 220. The hysteresis compensation unit 60 includes a compensation calculation unit 20, an update unit 64, and a storage unit 62. The hysteresis compensation unit 60 may be provided outside the control device 100.

[0052] The storage unit 62 stores the most recent maximum and minimum values ​​of the operation signal Sm or the drive signal Sdr as hysteresis information. For example, the storage unit 62 stores the operation signal Sm or the drive signal Sdr as hysteresis information.

[0053] The update unit 64 outputs an update instruction signal Su to the memory unit 62 so that the memory unit 62 stores the most recent maximum and minimum values ​​of the operation signal Sm or the drive signal Sdr. For example, the update unit 64 acquires the drive signal Sdr output by the control device 100 and determines the timing of updating the memory unit 62 according to a change in the drive signal Sdr.

[0054] The control device 100 of this embodiment acquires hysteresis information as compensation information Ic and compensates for the characteristic fluctuation of the shape memory alloy 220. The influence of fluctuations in the deformation characteristics due to the hysteresis of the shape memory alloy 220 is reduced, and the position accuracy and responsiveness of the movable part 210 can be improved.

[0055] 5B shows an example of hysteresis of the shape memory alloy 220. The vertical axis shows the length of the shape memory alloy 220, and the horizontal axis shows the drive signal Sdr. The solid line shows the case where the drive signal Sdr is swept to increase and the shape memory alloy 220 is heated. The dashed line shows the case where the drive signal Sdr is swept to decrease and the shape memory alloy 220 is dissipated.

[0056] The shape memory alloy 220 has hysteresis and shows different deformation characteristics in the heating direction and heat dissipation direction of the drive signal Sdr. For example, points A to C are points where the heat dissipation direction of the drive signal Sdr changes from the heating direction. Points D to F are points where the heat dissipation direction of the drive signal Sdr changes from the heating direction to the heat dissipation direction.

[0057] In this way, the magnitude of the drive signal Sdr required to control the shape memory alloy 220 differs depending on the driving state of the actuator 200. The drive signal output section 50 may output the drive signal Sdr compensated with different compensation amounts for the heating direction and the heat dissipation direction of the drive signal Sdr.

[0058] FIG. 5C shows the deformation characteristics of the shape memory alloy 220 due to the first amplitude vibration. The vertical axis shows the length of the shape memory alloy 220, and the horizontal axis shows the drive signal Sdr. In this example, the control device 100 determines the required drive signal Sdr based on the frequency response and transient response when the shape memory alloy 220 is expanded or contracted from the MAX side to the MIN side at the first amplitude. The first amplitude is an amplitude of a different magnitude from the second amplitude described later.

[0059] FIG. 5D shows the deformation characteristics of the shape memory alloy 220 due to the second amplitude vibration. The vertical axis shows the length of the shape memory alloy 220, and the horizontal axis shows the drive signal Sdr. In this example, the control device 100 determines the required drive signal Sdr based on the frequency response and transient response when the shape memory alloy 220 is expanded or contracted at the second amplitude. The second amplitude in this example is larger than the first amplitude.

[0060] In this way, the magnitude of the hysteresis of the shape memory alloy 220 also differs depending on the target value of the shape memory alloy 220. For example, the drive signal Sdr required for the length of the shape memory alloy 220 to become the reference value changes depending on the hysteresis of the shape memory alloy 220. Therefore, the magnitude of the required compensation amount also differs depending on the hysteresis of the shape memory alloy 220. In one example, the hysteresis compensation amount is determined so that the response characteristics of the first amplitude vibration and the second amplitude vibration are equivalent. This reduces the influence of the amplitude of the shape memory alloy 220.

[0061] For example, the control device 100 may change the compensation amount depending on the position of the point where the drive signal Sdr immediately before turns back from the heat dissipation direction to the heating direction, even when the drive signal Sdr is swept in the heating direction in Fig. 5B. In Fig. 5B, the compensation amount required when the drive signal Sdr is swept in the heating direction also changes depending on the magnitude of the turning back drive signal Sdr (e.g., points A to C, etc.). Similarly, in Fig. 5B, the compensation amount required when the drive signal Sdr is swept in the heat dissipation direction also changes depending on the magnitude of the turning back drive signal Sdr (e.g., points D to F, etc.).

[0062] 5E is a diagram for explaining the operation of the hysteresis compensation unit 60. The vertical axis indicates the amount of operation by the operation signal Sm, and the horizontal axis indicates an arbitrary time t.

[0063] The hysteresis information in this example is history information of the drive signal Sdr of the shape memory alloy 220. The history information includes turn-around information regarding the turn-around of the sweep direction of the drive signal Sdr. The turn-around information includes turn-around information on the MAX side of the drive signal Sdr when the drive signal Sdr changes from a heating direction to a heat dissipation direction. The turn-around information also includes turn-around information on the MIN side of the drive signal Sdr when the drive signal Sdr changes from a heat dissipation direction to a heating direction. Note that the history information is not limited to the drive signal Sdr, and may be information based on the operation signal Sm or the displacement signal Sd.

[0064] The MAX side turn-back information is an example of first turn-back information. The MAX side turn-back points correspond to points D to F in Fig. 5B. The MIN side turn-back information is an example of second turn-back information. The MIN side turn-back points correspond to points A to C in Fig. 5B.

[0065] Time t1 indicates the timing when the direction turns from the heating direction to the heat dissipation direction. At time t1, the update unit 64 resets the turn-back information (i.e., the MAX side turn-back information) related to the drive signal Sdr when the direction turns from the heating direction to the heat dissipation direction, which has been stored in the storage unit 62. From time t1 to time t3, the storage unit 62 stores the drive signal Sdr at time t1 as the MAX side peak hold value.

[0066] Time t2 indicates the timing when the direction turns back from the heat dissipation direction to the heating direction. At time t2, the update unit 64 resets the turn-back information (i.e., the MIN side turn-back information) related to the drive signal Sdr when the direction turns from the heat dissipation direction to the heating direction, which was stored in the storage unit 62. From time t2 to time t4, the storage unit 62 stores the drive signal Sdr at time t2 as the MIN side peak hold value.

[0067] In this manner, the storage unit 62 stores the immediately preceding MAX side turn-back information or MIN side turn-back information. The hysteresis compensation unit 60 compensates for the hysteresis of the shape memory alloy 220 while updating the MAX side peak hold value and the MIN side peak hold value.

[0068] The control device 100 of this embodiment can appropriately maintain the wire tension of the shape memory alloy 220 by compensating for and controlling the characteristic fluctuation of the shape memory alloy 220. This can prevent the shape memory alloy 220 from being overtightened or loosened. The control device 100 of this embodiment can also dynamically change the compensation amount of the shape memory alloy 220 based on the latest history information.

[0069] Furthermore, the control device 100 of this embodiment can improve the responsiveness of the movable part 210 by appropriately maintaining the wire tension of the shape memory alloy 220 and eliminating overtightening and slackening of the shape memory alloy 220. By improving the responsiveness of the movable part 210, the heating time of the shape memory alloy 220 can be shortened. By appropriately maintaining the wire tension, excessive wire tension can be avoided and damage to the shape memory alloy 220 can be suppressed. Therefore, the reliability and responsiveness of the actuator 200 can be improved.

[0070] 6A is a diagram for explaining an example of a method for setting the drive current Id. The actuator 200 of this example includes a movable part 210, a shape memory alloy 220a, a shape memory alloy 220b, and a position detection part 230. The shape memory alloy 220a and the shape memory alloy 220b correspond to the shape memory alloy A and the shape memory alloy B, respectively.

[0071] The position detection unit 230 functions as a position sensor that detects the position of the movable part 210. For example, the position detection unit 230 detects the position of the movable part 210 using a position sensor (for example, a Hall element). The position detection unit 230 may also calculate the length of the shape memory alloy 220 from the resistance value of the shape memory alloy 220 to indirectly detect the position of the movable part 210.

[0072] The operation amount Sm0 is the operation amount at a reference position of the movable part 210. The reference position in this example is a position where the lengths of the shape memory alloy 220a and the shape memory alloy 220b are equal.

[0073] The wire length L0 is the length of the shape memory alloy 220 when the movable part 210 is located at the reference position. The shape memory alloy 220a and the shape memory alloy 220b in this example are set to the wire length L0 by being supplied with a predetermined bias current Ib.

[0074] 6B is a diagram for explaining an example of a method for setting the drive current Id. In this example, the drive current Id supplied to the shape memory alloy 220a is increased and the drive current Id supplied to the shape memory alloy 220b is decreased, thereby making the operation amount larger than Sm0. The wire length of the shape memory alloy 220a is shorter than the reference wire length L0, and the wire length of the shape memory alloy 220b is longer than the reference wire length L0.

[0075] 6C is a diagram for explaining an example of a method for setting the drive current Id. Because the deformation characteristics of the wire length with respect to the drive current Id change between the shape memory alloy 220a and the shape memory alloy 220b due to hysteresis, the drive current Id required to set the same wire length differs from that required for the shape memory alloy 220a.

[0076] In the shape memory alloy 220a, the driving current Id for setting the operation amount Sm0 and wire length L0 corresponding to the reference position is smaller than that in the case of Fig. 6A. On the other hand, in the shape memory alloy 220b, the driving current Id for setting the operation amount Sm0 and wire length L0 corresponding to the reference position is larger than that in the case of Fig. 6A. The control device 100 of this example can set the movable part 210 to the reference position by compensating for hysteresis, and appropriately maintain the wire tension of the shape memory alloy 220.

[0077] 7A shows an example of the configuration of a control device 100 that compensates for characteristic variations according to other-axis displacement. The control device 100 of this example includes a other-axis displacement compensation unit 70 in a compensation calculation unit 20. The control device 100 of this example controls the driving of an actuator 200 in which a movable part 210 is displaceable in at least two axial directions. For example, the movable part 210 is displaced in a predetermined driving direction and in a other-axis direction that is at least one axial direction among axial directions different from the driving direction.

[0078] The other-axis displacement compensation unit 70 outputs compensation information Ic for compensating for interference of the movable part 210 with the displacement of its own axis due to the displacement of the other axis in response to the current displacement information. The current displacement information input to the other-axis displacement compensation unit 70 may be the same as the current displacement information input to the displacement signal output unit 30. The target signal Sg of the other axis may be used as the current displacement information. The current displacement information and the target signal Sg of the other axis are examples of the compensation information Ic input to the compensation calculation unit 20. The other-axis displacement compensation unit 70 of this example outputs displacement information related to the displacement in the other-axis direction to the compensation calculation unit 20 as compensation information Ic. The compensation calculation unit 20 generates a compensation signal Sc for compensating for the characteristic fluctuation of the shape memory alloy 220 based on the displacement in the other-axis direction.

[0079] FIG. 7B shows an example of a shape memory alloy 220 in which a displacement point Ed is displaced in the driving direction and in the other axis direction. The displacement point Ed of the shape memory alloy 220a is connected to the displacement point Ed of the shape memory alloy 220b. The displacement point Ed of this example is displaced in the driving direction (i.e., the Y-axis direction) and in the other axis direction (i.e., the X-axis direction). In this example, a case where the displacement point Ed is located at point M and a case where the displacement point Ed is located at point N are shown. Point M and point N have the same coordinate in the driving direction, but different coordinate in the other axis direction. Therefore, even if the position in the driving direction is the same, the length of the shape memory alloy 220 may differ.

[0080] When the displacement point Ed is located at point M, the lengths of the shape memory alloy 220a and the shape memory alloy 220b are La and Lb, respectively. When the displacement point Ed is located at point M, the lengths of the shape memory alloy 220a and the shape memory alloy 220b are equal, and La = Lb. In this case, the wire tension of the shape memory alloy 220a and the wire tension of the shape memory alloy 220b are equal.

[0081] On the one hand, when the displacement point Ed is located at point N, the lengths of the shape memory alloy 220a and the shape memory alloy 220b are La' and Lb', respectively. When the displacement point Ed is located at point N, the shape memory alloy 220a is shorter than the shape memory alloy 220b, and La' < Lb'. In this case, the shape memory alloy 220a is more likely to loosen than the shape memory alloy 220b. Thus, the relationship between the position of the displacement point Ed and the lengths of the shape memory alloy 220a and the shape memory alloy 220b also changes due to the displacement in the other-axis direction.

[0082] For example, when the displacement point Ed is located at point N, the control device 100 outputs different drive signals Sdr for the shape memory alloy 220a and the shape memory alloy 220b to compensate for the interference of the displacement in the other axis of the shape memory alloy 220 on the displacement in its own axis. The control device 100 in this example compensates the drive signal Sdr applied to the shape memory alloy 220 based on the compensation information Ic including the displacement information regarding the displacement in the other-axis direction. Thereby, the influence of the displacement in the other-axis direction can be suppressed.

[0083] FIG. 8 shows an example of the configuration of the control device 100 that compensates for characteristic variations according to temperature. The control device 100 in this example includes a temperature compensation unit 80 in the compensation calculation unit 20.

[0084] The temperature compensation unit 80 acquires temperature information from an arbitrary temperature sensor. The temperature information is an example of the compensation information Ic input to the compensation calculation unit 20. For example, the temperature compensation unit 80 acquires the ambient temperature of the actuator 200 as the temperature information. The temperature compensation unit 80 outputs the compensation information Ic including the temperature information to the compensation calculation unit 20 in order to compensate for the characteristic variations of the shape memory alloy 220 according to temperature. The temperature compensation unit 80 and the temperature sensor may be provided outside the control device 100. In this case, the compensation calculation unit 20 acquires the compensation information Ic from outside the control device 100.

[0085] The temperature of the shape memory alloy 220 is determined depending on the environmental temperature and the heat dissipation caused by the current. Therefore, the higher the environmental temperature, the easier the shape memory alloy 220 contracts, and the lower the environmental temperature, the easier the shape memory alloy 220 expands. For example, when the environmental temperature of the actuator 200 is higher than a predetermined reference temperature, the compensation calculation unit 20 makes the magnitude of the drive signal Sdr smaller than the reference value. On the other hand, when the environmental temperature of the actuator 200 is lower than the predetermined reference temperature, the compensation calculation unit 20 may make the magnitude of the drive signal Sdr larger than the reference value. Note that, when the compensation information Ic includes hysteresis information in addition to temperature information, the compensation calculation unit 20 may compensate for the hysteresis information according to the temperature information.

[0086] 9 shows an example of the configuration of a control device 100 that compensates for characteristic variations according to the attitude of the actuator 200. The control device 100 of this example includes an attitude compensation unit 90 in the compensation calculation unit 20.

[0087] The posture compensation unit 90 acquires posture information of the actuator 200. The posture information is an example of compensation information input to the compensation calculation unit 20. The posture compensation unit 90 may acquire the posture information from gravitational acceleration information of an acceleration sensor. The length and wire tension of the shape memory alloy 220 may change depending on the posture of the actuator 200. The posture compensation unit 90 of this example outputs compensation information Ic including the posture information to the compensation calculation unit 20 to compensate for the change in deformation characteristics that the posture of the actuator 200 causes to the shape memory alloy 220.

[0088] The attitude information may be acquired by a sensor, such as an acceleration sensor, provided in the actuator 200. In one example, the attitude information includes information corresponding to a change in magnetic flux density acquired by the sensor.

[0089] The control device 100 of this example may have multiple channels in the drive signal output section 50, as in the embodiment of Figures 3A and 3B. In this case, the drive signal output section 50 has multiple channels corresponding to the multiple shape memory alloys 220, and outputs drive signals Sdr compensated with different compensation amounts to each of the multiple shape memory alloys 220 according to the posture information. This allows the control device 100 to compensate for characteristic fluctuations according to the posture of the actuator 200 for each of the multiple shape memory alloys 220.

[0090] The control device 100 of this embodiment may be used in appropriate combination with other embodiments. The control device 100 may include at least one of a hysteresis compensation unit 60, a different axis displacement compensation unit 70, a temperature compensation unit 80, and an attitude compensation unit 90. That is, the control device 100 compensates for at least one of a characteristic variation according to hysteresis, a characteristic variation according to a different axis displacement, a characteristic variation according to temperature, or a characteristic variation according to attitude information.

[0091] 10A is a diagram for explaining a method for determining the compensation amount of the drive signal Sdr. The diagram shows the relationship between the compensation amount of the drive signal Sdr and the position control error, and the relationship between the compensation amount of the drive signal Sdr and the tracking ability. The compensation amount of the drive signal Sdr is a compensation amount for increasing or decreasing the drive signal Sdr based on the bias signal Sb. The compensation amount of the drive signal Sdr is set so as to be within the allowable error range of the position control error and to provide high tracking ability.

[0092] 10B shows an example of a method for determining the compensation amount. In this example, a method for determining the compensation amount for compensating for the characteristic fluctuation of the shape memory alloy 220 will be described.

[0093] In step S100, the compensation amount is set to a predetermined minimum value. The minimum value of the compensation amount may be set arbitrarily. In step S102, the position control error is measured.

[0094] In step S104, it is determined whether the position control error is within the allowable range. If the position control error is within the allowable range, the process proceeds to step S106, and if the position control error is not within the allowable range, the process proceeds to step S112.

[0095] In step S106, the transient response characteristics are measured. Then, in step S108, it is determined whether or not the tracking ability of the shape memory alloy 220 has improved based on the measurement results of the transient response characteristics. If the tracking ability of the shape memory alloy 220 has improved, the process proceeds to step S110, and the compensation amount by which the tracking ability has improved is stored as a provisional compensation amount. If the tracking ability of the shape memory alloy 220 has not improved, the process proceeds to step S112.

[0096] In step S112, it is determined whether the compensation amount is less than a predetermined maximum value. If the compensation amount is less than the maximum value, the process proceeds to step S114. If the compensation amount is not less than the maximum value, the process proceeds to step S116. If the compensation amount is less than the maximum value in step S114, the compensation amount is increased and the process returns to step S102. In step S116, the provisional value stored in step S110 is set as the compensation amount, and the adjustment is terminated. Note that if there is no provisional value stored in step S110, the compensation amount may be set to a predetermined minimum value. The method for determining the compensation amount in this example makes it possible to determine a compensation amount that improves tracking performance within a predetermined range of the compensation amount and within an allowable range of the position control error.

[0097] The method of determining the compensation amount in this example may be executed for each item to be compensated for. That is, the control device 100 determines the compensation amount for each of the characteristic variation corresponding to hysteresis, the characteristic variation corresponding to the other axis displacement, the characteristic variation corresponding to the attitude information, and the characteristic variation corresponding to temperature. For example, the control device 100 determines the compensation amount in the order of the characteristic variation corresponding to hysteresis, the characteristic variation corresponding to the other axis displacement, the characteristic variation corresponding to the attitude information, and the characteristic variation corresponding to temperature, according to the flowchart of this example.

[0098] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the description of the claims that such modifications and improvements can also be included in the technical scope of the present invention.

[0099] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and may be realized in any order unless the output of a previous process is used in a later process. Even if the operational flow in the claims, specifications, and drawings is explained using "first," "next," etc. for convenience, it does not mean that it is essential to perform the process in this order. [Explanation of symbols]

[0100] 10... target signal setting section, 20... compensation calculation section, 30... displacement signal output section, 40... control section, 50... drive signal output section, 52... bias signal generation section, 60... hysteresis compensation section, 62... memory section, 64... update section, 70... other axis displacement compensation section, 80... temperature compensation section, 90... attitude compensation section, 100... control device, 200... actuator, 210... moving section, 220... shape memory alloy, 225... bias member, 230... position detection section

Claims

1. A control device that controls driving of an actuator by deforming a shape memory alloy connected to a movable part of the actuator, a target signal setting unit that sets a target signal according to a target displacement of the actuator; a compensation calculation unit that outputs a compensation signal based on predetermined compensation information; a position detection unit that detects the position of the movable unit using a position sensor; a displacement signal output unit that acquires an output from the position sensor and outputs a displacement signal corresponding to current displacement information of the movable part in response to a change in the output of the position sensor; a control unit that outputs an operation signal according to the target signal, the displacement signal, and the compensation signal; a drive signal output unit that outputs a drive signal corresponding to the operation signal to the actuator; Equipped with the compensation information includes attitude information of the actuator, The compensation calculation unit outputs the compensation signal for compensating for a change in the length or tension of the shape memory alloy according to the posture information. Control device.

2. The attitude information is calculated based on gravitational acceleration information. The control device according to claim 1 .

3. the drive signal includes a bias signal for setting the temperature of the shape memory alloy in a transformation temperature range; The drive signal output unit increases or decreases the drive signal based on the bias signal in response to the operation signal. The control device according to claim 1 or 2.

4. The drive signal output unit outputs the drive signal compensated with different compensation amounts depending on whether the drive signal is in a heating direction or a heat dissipation direction. The control device according to claim 3 .

5. A plurality of the shape memory alloys are provided, The drive signal output unit has a plurality of channels corresponding to the plurality of shape memory alloys, and outputs the drive signal compensated with a different compensation amount to each of the plurality of shape memory alloys according to the posture information. The control device according to claim 3 or 4.

6. the plurality of shape memory alloys are connected to the movable part in a push-pull arrangement; The drive signal output unit outputs the drive signal compensated with different compensation amounts to a first shape memory alloy and a second shape memory alloy paired with the first shape memory alloy among the plurality of shape memory alloys. The control device according to claim 5 .

7. The position sensor is provided inside the control device. The control device according to any one of claims 1 to 6.

8. A control method for controlling driving of an actuator by deforming a shape memory alloy connected to a movable part of the actuator, comprising: setting a target signal corresponding to a target displacement of the actuator; outputting a compensation signal for compensating for a change in length or tension of the shape memory alloy according to predetermined compensation information including posture information of the actuator; detecting the position of the movable part using a position sensor; acquiring an output from the position sensor, and outputting a displacement signal corresponding to current displacement information of the movable part in response to a change in the output of the position sensor; outputting an operation signal according to the target signal, the displacement signal, and the compensation signal; outputting a drive signal to the actuator based on the operation signal; Equipped with Control method.

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