Driving displacement calibration device and method for shape memory alloy actuator

Abstract

The invention belongs to the field of shape memory alloy actuator control, and relates to a shape memory alloy actuator driving displacement calibration device and method.The device comprises a shape memory alloy actuator, a position detection unit, an electric signal measuring unit and a driving control unit; the position detection unit sends a feedback signal to the driving control unit; the electric signal measuring unit measures an electric signal of the shape memory alloy actuator and sends the electric signal to the driving control unit; the driving control unit is used for calculating the feedback signal and the electric signal to obtain a driving displacement-electric signal function, and driving the shape memory alloy actuator according to an expected driving displacement instruction and the driving displacement-electric signal function to displace the load to an expected position; the problem of drifting of a driving displacement-electric signal relation function of the shape memory alloy actuator due to increase of the number of cycles is solved, and the displacement control precision of the shape memory alloy actuator is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of shape memory alloy actuator control, and in particular relates to a drive displacement calibration device and method for a shape memory alloy actuator. Background Art

[0002] Shape memory alloy actuators have high power output density and displacement accuracy. Under the action of temperature and stress, shape memory alloy actuators can achieve reversible strain. Because shape memory alloys can achieve efficient energy conversion and output of execution force, shape memory alloys have shown broad application prospects in the field of actuators. In addition, the memory function of shape memory alloys is very stable, and they can still maintain excellent performance after long-term use and multiple deformations. Compared with traditional motor drive technology, shape memory alloys have the advantages of low cost, flexible deformation mode, and fast response. As a multifunctional smart material, it has been widely used in aerospace, medical equipment and other fields.

[0003] At present, researchers have developed a shape memory alloy actuator displacement control method based on resistance feedback, that is, by detecting the real-time resistance of the shape memory alloy actuator, the corresponding displacement of the shape memory alloy actuator is further obtained from the resistance-displacement linear function. The advantage of this control method is that it does not require an additional displacement sensor to synchronously measure the real-time position, and the resistance-displacement self-feedback is achieved through the resistance characteristics of the shape memory alloy. This control method greatly expands the application range of shape memory alloys. For example: in micro-robot applications, actuators designed with shape memory alloys can be miniaturized. This type of actuator obtains the relationship between the electrical signal and the displacement according to the driving displacement-electrical signal relationship function, and can also achieve precise displacement control without a displacement measurement sensor.

[0004] However, after tens of thousands of or more cycles of displacement, the shape memory alloy actuator will experience fatigue relaxation. That is, due to the increase in crystal structure defects of the material itself, the shape memory alloy actuator will experience drift in the driving displacement-electrical signal relationship function as the number of cycles increases. If the initial driving displacement-electrical signal relationship function is still used to perform feedback displacement control of the shape memory alloy actuator at this time, the displacement control accuracy will be significantly reduced. Summary of the invention

[0005] In view of this, the present invention provides a drive displacement calibration device and method for a shape memory alloy actuator, which can solve the drift problem of the drive displacement-electrical signal relationship function of the shape memory alloy actuator caused by an increase in the number of cycles, and significantly improve the displacement control accuracy of the shape memory alloy actuator.

[0006] The technical solution of the present invention is:

[0007] A drive displacement calibration device for a shape memory alloy actuator, comprising a shape memory alloy actuator for driving a load to move, and further comprising:

[0008] At least two position detection units are arranged at intervals and are used to detect the position of the load. When the load moves to the position where the position detection unit is located, the position detection unit sends a feedback signal;

[0009] an electrical signal measuring unit, electrically connected to the shape memory alloy actuator, and used to measure the electrical signal of the shape memory alloy actuator in real time and send the electrical signal;

[0010] A drive control unit is electrically connected to the shape memory alloy actuator. The drive control unit receives the feedback signal and the electrical signal, and calculates the position of the position detection unit corresponding to the feedback signal and the electrical signal to obtain a drive displacement-electrical signal function. The drive control unit drives the shape memory alloy actuator to move the load to the expected position according to the expected drive displacement instruction and the drive displacement-electrical signal function.

[0011] Preferably, the plurality of position detection units are arranged along a straight line, and the direction of the load displacement is parallel to the straight line.

[0012] Preferably, the electrical signal includes the resistance or potential of the shape memory alloy actuator.

[0013] Preferably, the driving control unit includes one of a current driving control unit, a laser driving unit, a fuel driving unit or a thermal radiation driving unit.

[0014] Preferably, the shape memory alloy actuator comprises one of a shape memory alloy wire, a spring, a compression spring, a film, and a braided bundle, and the shape memory alloy wire, the spring, the compression spring, the film, and the braided bundle are all made of conductive materials.

[0015] Preferably, the position detection unit includes one of a photoelectric proximity switch, a capacitive proximity switch, an inductive proximity switch or a magnetically sensitive proximity switch.

[0016] A method for calibrating the driving displacement of a shape memory alloy actuator, the method comprising the following steps:

[0017] At least two position detection units are arranged at intervals, and the positions y of the position detection units are recorded respectively;

[0018] Adjusting the driving power of the driving control unit from low to high to drive the shape memory alloy actuator to displace the load;

[0019] When the load moves to the position of each position detection unit, the position detection unit sends a feedback signal to the drive control unit, and the drive control unit records the electrical signal x received at the corresponding position respectively;

[0020] According to the position y of the position detection unit and the electrical signal x received at the corresponding position, a driving displacement-electrical signal relationship function y=f(x) is obtained;

[0021] According to the driving displacement-electrical signal relationship function y=f(x), the driving control unit provides the shape memory alloy actuator with current power corresponding to the electric signal x, and the shape memory alloy actuator drives the load to the position y corresponding to the expected displacement.

[0022] Preferably, the method for arranging the position detection unit includes:

[0023] The shape memory alloy actuator is operated by driving the control unit to drive the load displacement;

[0024] gradually increasing the power applied to the shape memory alloy actuator to obtain a maximum displacement and a minimum displacement of the load displacement;

[0025] At least two position detection units are arranged at intervals in a driving displacement linear section between a maximum displacement amount and a minimum displacement amount.

[0026] Preferably, when two position detection units are arranged, the method for obtaining the driving displacement-electrical signal relationship function y=f(x) according to the position of the position detection unit and the electrical signal received at the corresponding position includes:

[0027] When the load is displaced to the first position detection unit, the current electrical signal x1 is recorded, and the calibration position A1 (x1, y1) on the driving displacement-electrical signal relationship function y=f(x) can be obtained according to the position y1 of the first position detection unit;

[0028] When the load is displaced to the second position detection unit, the current electrical signal x2 is recorded, and the calibration position A2 (x2, y2) on the driving displacement-electrical signal relationship function y=f(x) can be obtained according to the position y2 of the second position detection unit;

[0029] The driving displacement-electrical signal function relationship of the linear segment between the maximum position and the minimum position is expressed as a linear function, and the expression y=kx+b of the y=f(x) function is obtained according to the calibration positions A1 and A2.

[0030] Preferably, when more than two position detection units are arranged, the method for obtaining the driving displacement-electrical signal relationship function y=f(x) according to the position of the position detection unit and the electrical signal received at the corresponding position includes:

[0031] When the load moves to the Nth position detection unit, the current electrical signal x is recorded. n , according to the position y of the Nth position detection unit n The calibration positions A1(x1,y1), A2(x2,y2)...A on the driving displacement-electrical signal relationship function y=f(x) can be obtained. n (x n ,y n );

[0032] According to multiple calibration positions A1, A2...A n , realize the nonlinear functional relationship between the maximum displacement and the minimum displacement, and convert y=f(x)=k1x+k2x 2 +kx+……k n-1 x n-1 +b is fitted into polynomial functions of different series.

[0033] Compared with the prior art, the drive displacement calibration device and method of a shape memory alloy actuator provided by the present invention have the following beneficial effects:

[0034] 1. The present invention detects the position of the load by setting a position detection unit. When the load moves to the position where the position detection unit is located, the position detection unit sends a feedback signal, which is a position signal corresponding to a displacement. The electrical signal measurement unit sends an electrical signal to the drive control unit. At this time, the load drive control unit re-obtains a drive displacement-electrical signal function based on the feedback signal and the electrical signal calculation, which can effectively overcome the problem that the initial drive displacement-electrical signal relationship function of the shape memory alloy actuator is reduced in accuracy due to material fatigue relaxation during the cycle, thereby improving the displacement control accuracy and efficiency of the shape memory alloy actuator.

[0035] 2. The drive displacement calibration device of the shape memory alloy actuator of the present invention has a simple structure and high calibration accuracy, and can realize the calibration of the resistance-displacement linear function for shape memory alloy actuators such as shape memory alloy wires, springs, compression springs, films, and braided bundles.

[0036] 3. The drive displacement calibration device of the shape memory alloy actuator of the present invention adopts a low-cost position detection unit to replace the expensive laser displacement sensor or ultrasonic displacement sensor, thereby realizing the displacement calibration of the shape memory alloy actuator and effectively reducing the manufacturing cost of the calibration device.

[0037] 4. The drive displacement calibration method of the shape memory alloy actuator of the present invention has high flexibility and can realize the calibration of the drive displacement-electrical signal relationship function by combining multiple position detection units. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of a drive displacement calibration device according to an embodiment of the present invention.

[0039] Figure 2 4 is a flow chart of a driving displacement calibration method according to an embodiment of the present invention.

[0040] Figure 3 FIG. 4 is a schematic diagram of load displacement ΔL according to an embodiment of the present invention.

[0041] Figure 4 Schematic diagram of the relationship between the driving displacement ΔL and the electrical signal (resistance) and the electrical signal (resistance) drift under the same displacement condition according to an embodiment of the present invention.

[0042] Figure 5 It is a schematic diagram of the driving displacement-electrical signal relationship function before and after calibration according to an embodiment of the present invention.

[0043] Description of reference numerals:

[0044] 1-power supply, 2-electrical signal measuring unit, 3-position detecting unit, 4-driving control unit, 5-load, 6-shape memory alloy actuator, 7-wire. DETAILED DESCRIPTION

[0045] It should be noted that, in the description of the present invention, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0046] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0047] In addition, it should be noted that the connections involved in the present invention can be achieved by using conventional connection methods and do not involve any innovation.

[0048] The subject of the present invention is a drive displacement calibration device and method for a shape memory alloy actuator. The shape memory alloy will undergo reversible strain under the action of temperature and stress. When the temperature is higher than the austenite transformation end temperature (A f ), the interior of the shape memory alloy is mainly austenite phase. When the material is cooled to the martensite transformation start temperature (Ms ) or under stress, the austenite phase transforms into the martensite phase. Under the action of appropriate stress, by controlling the temperature of the shape memory alloy, the phase content ratio of martensite and austenite in the shape memory alloy can be regulated, thereby realizing the control of the shape (such as length) of the shape memory alloy. For example, the shape memory alloy wire shows a macroscopic displacement effect of contraction and elongation. In this process, the resistance of the shape memory alloy wire also changes with the length of the shape memory alloy wire.

[0049] Shape memory alloy actuators have high power output density and displacement accuracy. Under the action of temperature and stress, shape memory alloy actuators can achieve reversible strain. Because shape memory alloys can achieve efficient energy conversion and output of execution force, shape memory alloys have shown broad application prospects in the field of actuators.

[0050] At present, researchers have developed a shape memory alloy actuator displacement control method based on resistance feedback, that is, by detecting the real-time resistance of the shape memory alloy actuator, the corresponding displacement of the shape memory alloy actuator is further obtained from the resistance-displacement linear function. The advantage of this control method is that it does not require an additional displacement sensor to synchronously measure the real-time position, and the resistance-displacement self-feedback is achieved through the resistance characteristics of the shape memory alloy. This control method greatly expands the application range of shape memory alloys. For example: in micro-robot applications, actuators designed with shape memory alloys can be miniaturized. This type of actuator obtains the relationship between the electrical signal and the displacement according to the driving displacement-electrical signal relationship function, and can also achieve precise displacement control without a displacement measurement sensor.

[0051] However, after tens of thousands of or more cycles of displacement, the shape memory alloy actuator will experience fatigue relaxation. That is, due to the increase in crystal structure defects of the material itself, the shape memory alloy actuator will experience drift in the driving displacement-electrical signal relationship function as the number of cycles increases. If the initial driving displacement-electrical signal relationship function is still used to perform feedback displacement control of the shape memory alloy actuator at this time, the displacement control accuracy will be significantly reduced.

[0052] Based on the above reasons, the present invention provides a drive displacement calibration device and method for a shape memory alloy actuator to solve the above-mentioned technical problems. Figures 1 to 5 , the present invention is described in detail.

[0053] Example 1

[0054] The present embodiment provides a drive displacement calibration device for a shape memory alloy actuator, comprising a shape memory alloy actuator 6, a position detection unit 3, an electrical signal measurement unit 2, and a drive control unit 4. The shape memory alloy actuator 6 is used to drive the load to move. At least two position detection units 3 are arranged at intervals to detect the position of the load 5. When the load 5 moves to the position where the position detection unit 3 is located, the position detection unit 3 sends a feedback signal to the drive control unit 4. The electrical signal measurement unit 2 is electrically connected to the shape memory alloy actuator 6. The electrical signal measurement unit 2 is used to measure the electrical signal of the shape memory alloy actuator 6 in real time and send the measured electrical signal to the drive control unit 4. The drive control unit 4 receives the feedback signal and the electrical signal, and calculates the position of the position detection unit 3 corresponding to the feedback signal (i.e., the displacement of the load 5) and the electrical signal to obtain a drive displacement-electrical signal function. The drive control unit 4 is connected to the shape memory alloy actuator 6. The drive control unit 4 drives the shape memory alloy actuator 6 according to the expected drive displacement instruction and the drive displacement-electrical signal function to move the load 5 to the expected position.

[0055] like Figure 1 It is a schematic diagram of a driving displacement calibration device according to an embodiment of the present invention, which is used to calibrate the driving displacement-electrical signal relationship function of the shape memory alloy actuator 6. A plurality of position detection units are arranged along a straight line, and the displacement direction of the load 5 is parallel to the straight line.

[0056] The drive control unit 4 includes one of a current drive control unit, a laser drive unit, a fuel drive unit or a thermal radiation drive unit. The position detection unit 3 can use one of a photoelectric proximity switch, a capacitive proximity switch, an inductive proximity switch or a magnetic sensitive proximity switch. In the embodiment of the present invention, the shape memory alloy actuator 6 uses a shape memory alloy wire, and the position detection unit 3 uses 5 photoelectric proximity switches, wherein the shape memory alloy wire is not restrictive. The device can calibrate the drive displacement-electrical signal relationship function of different types of shape memory alloy actuators 6 such as shape memory alloy wire, spring, compression spring, film, braided bundle, etc., and the shape memory alloy wire, spring, compression spring, film, braided bundle are all made of conductive materials.

[0057] In addition, the photoelectric proximity switch in the embodiment of the present invention is not restrictive, and similar devices such as photoelectric, capacitive, inductive, and magnetic sensitive proximity switches, as well as integrating and embedding the similar devices into the shape memory alloy actuator are also within the scope of the present invention.

[0058] In the embodiment of the present invention, the shape memory alloy actuator 6 is naturally suspended, and the load 5 is matched according to the weight of the shape memory alloy actuator 6 in actual application (a 100g weight is used in this embodiment), and the driving control unit 4 controls the current to drive the shape memory alloy actuator 6 to displace the load 5, and the photoelectric proximity switch measures the real-time position of the load 5. At the same time, the electrical signal measuring unit 2 records the corresponding electrical signal when the load 5 is displaced to the predetermined position. In this embodiment, the electrical signal is a resistance signal. n and the corresponding electrical signal (resistance) x n The function expression of y=f(x) is obtained by the relationship, and the values ​​of k and b and the function expression are stored in the memory in the drive control unit, so that the drive control unit can subsequently provide the current power corresponding to the corresponding electrical signal according to the calibrated polynomial equation to drive the load to the expected position.

[0059] Figure 3 It is a schematic diagram of load displacement ΔL of an embodiment of the present invention. The load 5 is displaced upward from the initial position under the action of the shape memory alloy actuator 6. In the present invention, the upward displacement is positive, and the displacement is represented by ΔL. Figure 4 Schematic diagram of the relationship between the driving displacement ΔL and the electrical signal (resistance) of the embodiment of the present invention and the drift of the electrical signal (resistance) under the same displacement. It can be understood that as time increases (the current power gradually increases, and the temperature of the shape memory alloy actuator 6 gradually increases), the resistance of the shape memory alloy actuator 6 changes in an "S" curve during the heating process, such as Figure 4 As shown by the solid line in the "S"-shaped curve, the resistance gradually decreases with the increase of temperature. At the same time, the range of resistance change also corresponds to the displacement range of the shape memory alloy actuator 6 and the load 5, and the displacement ΔL increases with the decrease of resistance, that is, as the current power gradually increases, the greater the load displacement ΔL driven by the shape memory alloy actuator 6, the smaller the electrical signal (resistance) of the shape memory alloy actuator 6.

[0060] The drive displacement calibration device for the shape memory alloy actuator of the present invention can effectively overcome the problem of reduced accuracy of the drive displacement-electrical signal relationship function of the shape memory alloy actuator caused by material fatigue relaxation during the cycle process, thereby improving the displacement control accuracy and efficiency of the shape memory alloy actuator. The drive displacement calibration device for the shape memory alloy actuator of the present invention has a simple structure and high calibration accuracy, and can realize the calibration of the resistance-displacement linear function for shape memory alloy actuators such as shape memory alloy wires, springs, compression springs, films, and braided bundles. The drive displacement calibration device for the shape memory alloy actuator of the present invention adopts a low-cost position detection unit to replace the expensive laser displacement sensor or ultrasonic displacement sensor, thereby realizing the displacement calibration of the shape memory alloy actuator and effectively reducing the manufacturing cost of the calibration device.

[0061] Example 2

[0062] When the driving displacement-electrical signal relationship function is determined, each resistance value corresponds to only one displacement. However, after multiple cycles of displacement, due to fatigue relaxation of the shape memory alloy actuator 6, the corresponding resistance "S" curve drifts under the same displacement ΔL, such as Figure 4 The resistance "S" curve is shown by the dotted line. To solve this problem, the embodiment of the present invention adopts Figure 2 The specific steps of the drive displacement calibration of the shape memory alloy actuator shown are:

[0063] 1. Arrange at least two position detection units 3 at intervals, and record the positions of the position detection units 3:

[0064] The driving control unit 4 drives the shape memory alloy actuator 6 to move the load 5 upward, gradually increases the power applied to the shape memory alloy actuator 6 to obtain the minimum displacement and the maximum displacement of the load 5, and arranges 5 photoelectric proximity switches between the maximum displacement and the minimum displacement. The positions of the position detection units are y1, y2...y5 respectively.

[0065] 2. Adjust the driving power of the driving control unit 4 from low to high to drive the shape memory alloy actuator 6 to displace the load 5:

[0066] The electrical signal of the shape memory alloy actuator 6 is recorded in real time by the electrical signal measuring unit 2 . In this embodiment, the electrical signal is a resistance signal.

[0067] 3. When the load moves to different photoelectric proximity switches, the electrical signal measurement unit 2 records the corresponding electrical signal x n , according to the position y of the position detection unit n And the corresponding electrical signal x n , and obtain the calibration positions A1(x1,y1), A2(x2,y2)...A5(x5,y5).

[0068] 4. According to the position of the position detection unit 3 and the electrical signal received at the corresponding position, the driving displacement-electrical signal relationship function y=f(x) is obtained, and further according to multiple calibration positions, the nonlinear driving displacement-electrical signal relationship function y=f(x)=k1x+k2x is obtained. 2 +k3x 3 +……k n-1 x n-1 +b, in fact, there is a section of linear change of resistance and linear change of displacement ΔL between the maximum displacement and the minimum displacement ( Figure 4The resistance and displacement linear intervals are marked in the figure. The driving displacement-electrical signal function relationship of the linear segment is expressed as a linear function y=f(x)=kx+b (the linear function is y=f(x)=k1x+k2x 2 +k3x 3 +……k n-1 x n-1 +b non-linear functions include).

[0069] 5. According to the driving displacement-electrical signal relationship function y=f(x), the driving control unit can drive the shape memory alloy actuator 6 to displace the load to any point A within the maximum displacement and the minimum displacement. n (x n ,y n ).

[0070] In order to further improve the control accuracy of displacement, according to multiple calibration positions A1, A2...A n The nonlinear driving displacement-electrical signal relationship function y=f(x)=k1x+k2x is obtained 2 +k3x 3 +……k n-1 x n-1 +b.

[0071] When the shape memory alloy actuator undergoes fatigue relaxation after tens of thousands of cycles or more, that is, the shape memory alloy actuator has an increase in crystal structure defects of the material itself, and its driving displacement-electrical signal relationship function drifts due to the increase in the number of cycles, the driving displacement-electrical signal relationship function can be recalibrated by a driving displacement calibration device and method for a shape memory alloy actuator disclosed in the present invention, and a calibrated driving displacement-electrical signal relationship function can be obtained, such as Figure 5 The dotted line in the schematic diagram of the driving displacement-electrical signal relationship function before and after calibration of the embodiment of the present invention (including f1(x)=k1x+k2x 2 +k3x 3 +……k n-1 x n-1 +b1、f2(x)=k1x+k2x 2 +k3x 3 +……k n-1 x n-1 + b2), the calibrated driving displacement-electrical signal relationship function is only an example, and the driving displacement-electrical signal relationship function of the shape memory alloy actuator 6 is based on multiple calibration positions A in actual applications. n (x n ,y n ) can be obtained.

[0072] The drive displacement calibration method of the shape memory alloy actuator of the present invention has high flexibility and can realize the calibration of the drive displacement-electrical signal relationship function by combining multiple position detection units.

[0073] The above disclosure is only a preferred specific embodiment of the present invention, but the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A drive displacement calibration device for a shape memory alloy actuator, comprising a shape memory alloy actuator (6) for driving a load (5) to move, characterized in that: Also includes: At least two position detection units (3) are arranged at intervals and are used to detect the position of the load (5); when the load (5) moves to the position where the position detection unit (3) is located, the position detection unit (3) sends a feedback signal; An electrical signal measuring unit (2) is electrically connected to the shape memory alloy actuator (6), and the electrical signal measuring unit (2) is used to measure the electrical signal of the shape memory alloy actuator (6) in real time and send the electrical signal; A drive control unit (4) is electrically connected to the shape memory alloy actuator (6). The drive control unit (4) is used to receive the feedback signal and the electrical signal, and to calculate the position of the position detection unit (3) corresponding to the feedback signal and the electrical signal to obtain a drive displacement-electrical signal function. The drive control unit (4) drives the shape memory alloy actuator (6) according to the expected drive displacement instruction and the drive displacement-electrical signal function to move the load (5) to the expected position.

2. The drive displacement calibration device of the shape memory alloy actuator according to claim 1, characterized in that: The plurality of position detection units (3) are arranged along a straight line, and the direction in which the load (5) moves is parallel to the straight line.

3. The drive displacement calibration device of the shape memory alloy actuator according to claim 1, characterized in that: The electrical signal includes the resistance or potential of the shape memory alloy actuator (6).

4. The drive displacement calibration device of the shape memory alloy actuator according to claim 1, characterized in that: The driving control unit (4) comprises one of a current driving control unit, a laser driving unit, a fuel driving unit or a heat radiation driving unit.

5. The drive displacement calibration device for shape memory alloy actuator according to claim 1, characterized in that: The shape memory alloy actuator (6) comprises one of a shape memory alloy wire, a spring, a compression spring, a film, and a braided bundle, wherein the shape memory alloy wire, the spring, the compression spring, the film, and the braided bundle are all made of conductive materials.

6. The drive displacement calibration device for shape memory alloy actuator according to claim 1, characterized in that: The position detection unit (3) comprises one of a photoelectric proximity switch, a capacitive proximity switch, an inductive proximity switch or a magnetically sensitive proximity switch.

7. A method for calibrating the driving displacement of a shape memory alloy actuator, using the device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: At least two position detection units (3) are arranged at intervals to respectively record the positions y of the position detection units (3); Adjusting the driving power of the driving control unit (4) from low to high to drive the shape memory alloy actuator (6) to displace the load (5); When the load (5) is displaced to the position of each position detection unit (3), the position detection unit (3) sends a feedback signal to the drive control unit (4), and the drive control unit (4) respectively records the electrical signal x received at the corresponding position; According to the position y of the position detection unit (3) and the electrical signal x received at the corresponding position, a driving displacement-electrical signal relationship function y=f(x) is obtained; According to the driving displacement-electrical signal relationship function y=f(x), the driving control unit (4) provides the shape memory alloy actuator (6) with current power corresponding to the electric signal x, and the shape memory alloy actuator (6) drives the load (5) to the position y corresponding to the expected displacement.

8. The drive displacement calibration method of the shape memory alloy actuator according to claim 7, characterized in that: The method for arranging the position detection unit (3) comprises: The shape memory alloy actuator (6) is operated by driving the control unit (4) to drive the load (5) to move; gradually increasing the power applied to the shape memory alloy actuator (6) to obtain a maximum displacement and a minimum displacement of the load (5); At least two position detection units (3) are arranged at intervals in a driving displacement linear section between a maximum displacement and a minimum displacement.

9. The drive displacement calibration method of the shape memory alloy actuator according to claim 7, characterized in that: When two position detection units (3) are arranged, the method for obtaining the driving displacement-electrical signal relationship function y=f(x) according to the position of the position detection unit (3) and the electric signal received at the corresponding position comprises: When the load (5) is displaced to the first position detection unit (3), the current electrical signal x1 is recorded, and the calibration position A1 (x1, y1) on the driving displacement-electrical signal relationship function y=f(x) can be obtained according to the position y1 of the first position detection unit (3); When the load (5) is displaced to the second position detection unit (3), the current electrical signal x2 is recorded, and the calibration position A2 (x2, y2) on the driving displacement-electrical signal relationship function y=f(x) can be obtained according to the position y2 of the second position detection unit (3); The driving displacement-electrical signal function relationship of the linear segment between the maximum position and the minimum position is converted into a linear function, and the expression y=kx+b of the y=f(x) function is obtained according to the calibration positions A1 and A2.

10. The drive displacement calibration method of the shape memory alloy actuator according to claim 7, characterized in that: When more than two position detection units (3) are arranged, the method for obtaining the driving displacement-electrical signal relationship function y=f(x) according to the position of the position detection unit (3) and the electric signal received at the corresponding position comprises: When the load (5) moves to the Nth position detection unit (3), the current electrical signal x is recorded. n , according to the position y of the Nth position detection unit (3) n The calibration positions A1(x1,y1), A2(x2,y2)...A on the driving displacement-electrical signal relationship function y=f(x) can be obtained. n (x n ,y n ); According to multiple calibration positions A1, A2...A n , realize the nonlinear functional relationship between the maximum displacement and the minimum displacement, and convert y=f(x)=k1x+k2x 2 +k3x 3 +……k n-1 x n-1 +b is fitted into polynomial functions of different series.

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