JP7601566B2 - Control device and control method - Google Patents

Description

The present invention relates to a control device and a control method.

2. Description of the Related Art Conventionally, with respect to a control device for an actuator that is driven by deformation of a shape memory alloy, it is known that the response is improved by applying a bias current (for example, see Patent Document 1).
[Prior Art Literature]
[Patent Documents]
[Patent Document 1] Patent No. 4857550

We provide a control device that controls the drive of an actuator using a shape memory alloy in response to displacement fluctuations caused by gravitational acceleration.

In a first aspect of the present invention, a control device is provided that controls the drive of an actuator by deforming a shape memory alloy connected to a movable part of the actuator, and includes 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, and the compensation information includes attitude information of the actuator.

In a second aspect of the present invention, a control method for controlling the driving of an actuator by deforming a shape memory alloy connected to a movable part of the actuator is provided, 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, the compensation information including attitude information of the actuator.

Note that 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.

2 shows an example of the configuration of a control device 100. 4 shows an example of an operation flowchart of the control device 100. An example of the configuration of a bias type actuator 200 is shown. An example of the configuration of a push-pull type actuator 200 is shown. An example of the configuration of a push-pull type actuator 200 is shown. An example of the configuration of a bias type actuator 200 is shown. An example of the configuration of a push-pull type actuator 200 is shown. An example of the configuration of a push-pull type actuator 200 is shown. An example of the configuration of a push-pull type actuator 200 is shown. 2 shows an example of the configuration of a control device 100. 2 shows an example of the configuration of a control device 100. 13 is a diagram for explaining the deformation characteristics of a shape memory alloy 220. FIG. 1 shows an example of the configuration of a control device 100 that compensates for characteristic fluctuations due to hysteresis. 1 shows an example of hysteresis of the shape memory alloy 220. 4 shows the deformation characteristics of the shape memory alloy 220 due to the first amplitude vibration. 4 shows the deformation characteristics of the shape memory alloy 220 due to the second amplitude vibration. 10A and 10B are diagrams for explaining the operation of the hysteresis compensation unit 60. 10 is a diagram for explaining an example of a method for setting a drive current Id. FIG. 10 is a diagram for explaining an example of a method for setting a drive current Id. FIG. 10 is a diagram for explaining an example of a method for setting a drive current Id. FIG. 1 shows an example of the configuration of a control device 100 that compensates for characteristic variations according to other-axis displacements. 13 shows 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. 1 shows an example of the configuration of a control device 100 that compensates for characteristic variations according to temperature. 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. 11 is a diagram for explaining a method for determining a compensation amount for a drive signal Sdr. FIG. An example of a method for determining the compensation amount will be described.

The present invention will be described below through embodiments of the invention, but the following embodiments do not limit 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.

Figure 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.

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

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 the characteristic fluctuation of the shape memory alloy 220. For example, the characteristic fluctuation of the shape memory alloy 220 refers to the fluctuation of 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.

The compensation information Ic includes information necessary to compensate for the characteristic fluctuations 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.

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 to a transformation temperature region. The transformation temperature region will be described later. For example, when supplying a drive current Id in response to the drive signal Sdr, the drive signal output unit 50 supplies a bias current Ib as a bias signal Sb to the shape memory alloy 220.

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 regarding 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.

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 unit 30 outputs a displacement signal Sd corresponding to the resistance change of the shape memory alloy 220 to the control unit 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 this example, the control device 100 can improve the position accuracy and responsiveness of the movable part 210 by compensating for and controlling the characteristic fluctuation of the shape memory alloy 220.

The control unit 40 outputs an operation signal Sm to control the drive signal Sdr supplied to the actuator 200. In this example, the control unit 40 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 in 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.

The drive signal output unit 50 drives the actuator 200 by deforming the shape memory alloy 220 in response to the drive signal Sdr. The drive signal output unit 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 unit 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 multiple shape memory alloys 220, the drive signal output unit 50 may output the drive signal Sdr to each shape memory alloy 220. In another example, the drive signal output unit 50 may change the bias signal Sb it supplies to each shape memory alloy 220.

The bias signal generating unit 52 generates a bias signal Sb. Even if the actuator 200 has multiple shape memory alloys 220, the bias signal generating unit 52 may generate the same bias signal Sb for the multiple shape memory alloys 220. In this case, the control device 100 compensates with a different compensation amount for each of the multiple shape memory alloys 220. 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. Note that the bias signal generating unit 52 may generate different bias signals Sb for the multiple shape memory alloys 220.

The control device 100 in this example uses closed-loop control, which uses the displacement signal output unit 30 to feed back current position information of the controlled object and control it so that the difference with the target position converges to zero. However, the control device 100 may also 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.

Figure 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 reversed.

In step S16, an operation signal Sm is output. In step S18, a drive signal Sdr is output to the actuator 200 based on the operation signal Sm. Note that steps S10 to S18 may be executed repeatedly.

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

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 that is provided in an imaging device and refracts light that is 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.

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 achieved 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 when heated and expands when heat is dissipated. 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).

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

In this example, the actuator 200 is driven to adjust the movable part 210 provided in the imaging device. However, the actuator 200 may be used for other purposes as long as the drive is controlled by the shape memory alloy 220.

Figure 2A shows an example of the configuration of a bias type actuator 200. The actuator 200 of this example comprises 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 drive 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 drive direction (e.g., the Y-axis direction) by the thrust of the shape memory alloy 220 and the spring thrust.

For example, when the control device 100 starts to pass current through 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 passing current through 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.

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.

Figure 2B shows an example of the configuration of a push-pull type actuator 200. A plurality of shape memory alloys 220 are connected to the movable part 210 in a push-pull arrangement. The push-pull type actuator 200 operates by balancing the thrust of the plurality of shape memory alloys 220. The actuator 200 of this example comprises the movable part 210 and two shape memory alloys 220. The plurality of shape memory alloys 220 are each connected to the movable part 210 at the displacement point Ed.

The shape memory alloys 220a and 220b are arranged to extend in a predetermined driving direction (e.g., the Y-axis direction) and are arranged so that the thrusts of the shape memory alloys 220 balance each other. The movable part 210 is balanced by the two shape memory alloys 220 and displaces in the predetermined driving direction (e.g., the Y-axis direction).

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 with different compensation amounts to the shape memory alloy 220a and the shape memory alloy 220b. For example, the characteristic fluctuations of the shape memory alloy 220a and the shape memory alloy 220b may be compensated for with a compensation amount according to hysteresis or the attitude of the actuator 200, etc.

Figure 2C shows an example of the configuration of a push-pull type actuator 200. The actuator 200 of this example comprises a movable part 210, two shape memory alloys 220, and two bias members 225. The shape memory alloy 220 and the bias member 225 are each connected to the movable part 210 at the displacement point Ed. The shape memory alloy 220a and the bias member 225a are arranged so that the thrust of the shape memory alloy 220b and the bias member 225b is balanced in a predetermined driving direction (e.g., the Y-axis direction).

Figure 2D shows an example of the configuration of the bias 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 the 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.

Figure 2E shows an example of the configuration of a push-pull type actuator 200. The actuator 200 in this example comprises 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.

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

Figure 2F shows an example of the configuration of a push-pull type actuator 200. The actuator 200 in this example comprises 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 arranged to extend obliquely with respect to the driving direction of the movable part 210 (e.g., the X-axis direction and the Y-axis direction).

Figure 2G shows an example of the configuration of a push-pull type actuator 200. The actuator 200 in 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 the displacement point Ed.

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

Figure 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 Figure 1A in that the drive signal output unit 50 has multiple channels.

The drive signal output unit 50 has multiple channels, each of which outputs a drive signal Sdr. This makes it possible to output a different drive signal Sdr to each shape memory alloy 220 when the actuator 200 has multiple shape memory alloys 220. For example, the drive signal output unit 50 has multiple channels corresponding to the number of shape memory alloys 220, and outputs a drive signal Sdr corresponding to the deformation characteristics of each of the shape memory alloys 220. For example, when each of the multiple shape memory alloys 220 exhibits different deformation characteristics, the drive signal output unit 50 increases or decreases the bias signal Sb by an appropriate amount of operation according to the deformation characteristics. This makes it possible to prevent the actuator 200 from being driven in an unintended direction.

In this example, the control device 100 has a drive signal output unit 50 with multiple channels, so 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.

Figure 3B shows an example of the configuration of the control device 100. The control device 100 in this example will be described as moving the movable part 210 in two axial directions. In this example, differences from Figure 3A will be particularly described.

The control device 100 has multiple 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 in this example has two of each component corresponding to the first axis (e.g., X-axis) and the second axis (e.g., Y-axis).

The target signal setting unit 10a sets a target signal Sg according to target displacement information corresponding to a target displacement in the first axis direction. On the other hand, the target signal setting unit 10b sets a target signal Sg according to target displacement information corresponding to a target displacement in the second axis direction.

The displacement signal output unit 30a also acquires current displacement information of the shape memory alloy 220 corresponding to the current displacement in the first axis direction. On the other hand, the displacement signal output unit 30b acquires current displacement information of the shape memory alloy 220 corresponding to the current displacement in the second axis direction.

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 to 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.

Figure 4 is a diagram for explaining the deformation characteristics of shape memory alloy 220. Shape memory alloy 220 has a martensite phase and an austenite phase, and a transformation temperature range therebetween. Shape memory alloy 220 has the property of recovering its memorized shape when heated to a temperature equal to or higher than the reverse transformation end 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).

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. 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 exhibits excellent responsiveness even within the transformation temperature region. By eliminating excessive tension or slackness in the shape memory alloy 220, the responsiveness of the movable part 210 can be well controlled.

Figure 5A shows an example of the configuration of a control device 100 that compensates for characteristic variations due to hysteresis. The control device 100 of this example includes a hysteresis compensation unit 60. The compensation information Ic includes hysteresis information of the shape memory alloy 220.

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 memory unit 62. The hysteresis compensation unit 60 may be provided outside the control device 100.

The memory 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 memory unit 62 stores the operation signal Sm or the drive signal Sdr as hysteresis information.

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 the change in the drive signal Sdr.

The control device 100 of this example acquires hysteresis information as compensation information Ic and compensates for the characteristic fluctuations of the shape memory alloy 220. By reducing the influence of fluctuations in the deformation characteristics due to the hysteresis of the shape memory alloy 220, the positional accuracy and responsiveness of the movable part 210 can be improved.

Figure 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, causing the shape memory alloy 220 to heat up. The dashed line shows the case where the drive signal Sdr is swept to decrease, causing the shape memory alloy 220 to dissipate heat.

The shape memory alloy 220 has hysteresis and exhibits 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 to the heating direction. Points D to F are points where the heat dissipation direction of the drive signal Sdr changes to the heating direction.

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

Figure 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 below.

Figure 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.

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 reach 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 makes it possible to reduce the influence of the magnitude of the amplitude of the shape memory alloy 220.

For example, in FIG. 5B, even when the drive signal Sdr is swept in the heating direction, the control device 100 may change the compensation amount depending on the position of the point where the drive signal Sdr most recently turned back from the heat dissipation direction to the heating direction. In FIG. 5B, the compensation amount required when the drive signal Sdr is swept in the heating direction also varies depending on the magnitude of the turning 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 varies depending on the magnitude of the turning drive signal Sdr (e.g., points D to F, etc.).

Figure 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.

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 the heating direction to the 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 the heat dissipation direction to the 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.

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.

Time t1 indicates the timing when the direction changes from the heating direction to the heat dissipation direction. At time t1, the update unit 64 resets the turn-around information (i.e., the MAX side turn-around information) stored in the memory unit 62 regarding the drive signal Sdr when changing from the heating direction to the heat dissipation direction. From time t1 to time t3, the memory unit 62 stores the drive signal Sdr at time t1 as the MAX side peak hold value.

Time t2 indicates the timing when the direction changes from the heat dissipation direction to the heating direction. At time t2, the update unit 64 resets the turn-around information (i.e., the MIN side turn-around information) stored in the memory unit 62 regarding the drive signal Sdr when changing from the heat dissipation direction to the heating direction. From time t2 to time t4, the memory unit 62 stores the drive signal Sdr at time t2 as the MIN side peak hold value.

In this way, the memory unit 62 stores the immediately preceding MAX side turn-around information or MIN side turn-around 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.

The control device 100 of this example can appropriately maintain the wire tension of the shape memory alloy 220 by compensating for and controlling the characteristic fluctuations of the shape memory alloy 220. This makes it possible to prevent the shape memory alloy 220 from being overtightened or loosened. Furthermore, the control device 100 of this example can dynamically change the amount of compensation for the shape memory alloy 220 based on the latest historical information.

The control device 100 of this example 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.

Figure 6A is a diagram for explaining an example of a method for setting the drive current Id. The actuator 200 of this example comprises 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.

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 (e.g., 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.

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

The wire length L0 is the length of the shape memory alloy 220 when the movable part 210 is located at the reference position. In this example, the shape memory alloy 220a and the shape memory alloy 220b are set to the wire length L0 by supplying a predetermined bias current Ib.

Figure 6B is a diagram for explaining an example of a method for setting the drive current Id. In this example, the operation amount is made larger than Sm0 by increasing the drive current Id supplied to the shape memory alloy 220a and decreasing the drive current Id supplied to the shape memory alloy 220b. 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.

Figure 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 shape memory alloy 220a and shape memory alloy 220b due to hysteresis, the drive current Id required to set the same wire length differs.

In the shape memory alloy 220a, the drive current Id for setting the operation amount Sm0 and wire length L0 corresponding to the reference position is smaller than in the case of FIG. 6A. On the other hand, in the shape memory alloy 220b, the drive current Id for setting the operation amount Sm0 and wire length L0 corresponding to the reference position is larger than 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.

Figure 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 the compensation calculation unit 20. The control device 100 of this example controls the driving of an actuator 200 in which a movable part 210 can be displaced 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 of the axial directions different from the driving direction.

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 compensation information Ic input to the compensation calculation unit 20. The other-axis displacement compensation unit 70 of this example outputs displacement information regarding 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.

Figure 7B shows an example of a shape memory alloy 220 in which the 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. In this example, the displacement point Ed 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, the case where the displacement point Ed is located at point M and the 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 coordinates 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.

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.

On the other hand, when the displacement point Ed is located at point N, the lengths of the shape memory alloys 220a and 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' holds. In this case, the shape memory alloy 220a is more likely to loosen than the shape memory alloy 220b. In this way, the relationship between the position of the displacement point Ed and the lengths of the shape memory alloys 220a and 220b also changes depending on the displacement in the other axial direction.

For example, when the displacement point Ed is located at point N, the control device 100 compensates for interference with the displacement of the shape memory alloy 220 in its own axis due to the displacement of the other axis of the shape memory alloy 220 by outputting different drive signals Sdr for the shape memory alloy 220a and the shape memory alloy 220b. The control device 100 in this example compensates for the drive signal Sdr provided to the shape memory alloy 220 based on compensation information Ic, which includes displacement information regarding the displacement in the other axis direction. This makes it possible to suppress the effects of the displacement in the other axis direction.

Figure 8 shows an example of the configuration of a control device 100 that compensates for temperature-dependent characteristic variations. The control device 100 in this example includes a temperature compensation unit 80 in the compensation calculation unit 20.

The temperature compensation unit 80 acquires temperature information from an arbitrary temperature sensor. The temperature information is an example of 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 temperature information. The temperature compensation unit 80 outputs compensation information Ic including the temperature information to the compensation calculation unit 20 in order to compensate for the characteristic fluctuation of the shape memory alloy 220 according to the 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.

The temperature of the shape memory alloy 220 is determined depending on the environmental temperature and the heat dissipation caused by the passage of electricity. 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.

Figure 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.

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. In this example, the posture compensation unit 90 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.

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 changes in magnetic flux density acquired by the sensor.

The control device 100 of this example may have multiple channels in the drive signal output unit 50, as in the embodiment of Figures 3A and 3B. In this case, the drive signal output unit 50 has multiple channels corresponding to the multiple shape memory alloys 220, and outputs a drive signal Sdr compensated with a different compensation amount 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 corresponding to the posture of the actuator 200 for each of the multiple shape memory alloys 220.

The control device 100 of this example 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 the characteristic variations corresponding to hysteresis, the characteristic variations corresponding to different axis displacement, the characteristic variations corresponding to temperature, and the characteristic variations corresponding to attitude information.

Figure 10A is a diagram for explaining a method for determining the compensation amount of the drive signal Sdr. The figure 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 the 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.

Figure 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 variation of the shape memory alloy 220 is described.

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.

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. If the position control error is not within the allowable range, the process proceeds to step S112.

In step S106, the transient response characteristics are measured. Then, in step S108, it is determined whether 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.

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, proceed to step S114. If the compensation amount is not less than the maximum value, proceed to step S116. If the compensation amount is less than the maximum value in step S114, increase the compensation amount and return to step S102. In step S116, the provisional value stored in step S110 is set as the compensation amount, and 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 compensation amount determination method of this example makes it possible to determine a compensation amount that improves tracking within a predetermined range of compensation amount and within an acceptable range of position control error.

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 other axis displacement, the characteristic variation corresponding to attitude information, and the characteristic variation corresponding to temperature. For example, the control device 100 determines the compensation amount in the following order according to the flowchart of this example: the characteristic variation corresponding to hysteresis, the characteristic variation corresponding to other axis displacement, the characteristic variation corresponding to attitude information, and the characteristic variation corresponding to temperature.

The present invention has been described above using an embodiment, but the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiment. It is clear from the claims that forms with such modifications or improvements can also be included in the technical scope of the present invention.

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" or "prior to," and it should be noted that the processes may be performed 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 necessary to perform the processes in this order.

10: Target signal setting unit, 20: Compensation calculation unit, 30: Displacement signal output unit, 40: Control unit, 50: Drive signal output unit, 52: Bias signal generation unit, 60: Hysteresis compensation unit, 62: Memory unit, 64: Update unit, 70: Other axis displacement compensation unit, 80: Temperature compensation unit, 90: Attitude compensation unit, 100: Control device, 200: Actuator, 210: Movable unit, 220: Shape memory alloy, 225: Bias member, 230: Position detection unit

Claims (8)

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 corresponding 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 according 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 corresponding 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,
the compensation information includes attitude information of the actuator,
The compensation calculation unit outputs the compensation signal for compensating for a change in length or tension of the shape memory alloy in accordance with the posture information.
Control device. The control device according to claim 1 , wherein the attitude information is calculated based on gravitational acceleration information. The drive signal includes a bias signal for setting a temperature of the shape memory alloy in a transformation temperature region,
The control device according to claim 1 , wherein 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 3 , wherein the drive signal output unit outputs the drive signal that is compensated with different compensation amounts depending on whether the drive signal is in a heating direction or a heat dissipation direction. A plurality of the shape memory alloys are provided,
The control device according to claim 3 or 4, wherein 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 different compensation amounts to each of the plurality of shape memory alloys according to the posture information. The plurality of shape memory alloys are connected to the movable part in a push-pull arrangement;
The control device according to claim 5, wherein the drive signal output unit outputs the drive signal compensated with different compensation amounts to a first shape memory alloy among the plurality of shape memory alloys and a second shape memory alloy that pairs with the first shape memory alloy. The control device according to claim 1 , wherein the position sensor is provided inside the control device. 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 the posture information based on predetermined compensation information including posture information of the actuator ;
detecting a 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 corresponding to the target signal, the displacement signal, and the compensation signal;
and outputting a drive signal to the actuator based on the operation signal.
Control methods.

Images