WO2022267196A1

WO2022267196A1 - Driving method using sma line pair, and actuation structure and storage medium

Info

Publication number: WO2022267196A1
Application number: PCT/CN2021/111990
Authority: WO
Inventors: 刘述伦; 计数标; 蔡耀前
Original assignee: 广东海德亚科技有限公司
Priority date: 2021-06-23
Filing date: 2021-08-11
Publication date: 2022-12-29
Also published as: CN113534570A; CN113534570B

Abstract

A driving method using an SMA line pair, and an actuation structure and a storage medium, which relate to the technical field of actuators. The method comprises: providing an initial driving signal for an SMA line pair; acquiring a target feedback amount required for a movable element moving by a target displacement; measuring a first feedback amount of a first SMA line and a second feedback amount of a second SMA line; and according to the target feedback amount, the first feedback amount and the second feedback amount, continuously increasing the driving signal for the first SMA line by a first increment, and correspondingly decreasing the driving signal for the second SMA line by a first decrement, wherein the difference between the first increment and the first decrement satisfies a preset threshold value. Under an initial driving signal, corresponding driving signals are provided for a first SMA line and a second SMA line to respectively stretch and retract same, such that a movable element moves by a target displacement under the joint action of an SMA line pair, and the displacement precision is higher.

Description

Driving method, actuating structure and storage medium of SMA wire pair

This application claims the priority of the Chinese patent application submitted to the China Patent Office on June 23, 2021, with the application number 202110697766.X, and the title of the invention is "SMA line pair driving method, actuation structure and storage medium", all of which The contents are incorporated by reference in this application.

technical field

The present application relates to the technical field of actuators, and in particular to a driving method, an actuating structure and a storage medium of an SMA wire pair.

Background technique

As a common driving component, the actuator can be used for image stabilization, focusing or displacement driving according to the effect of its driving. Therefore, actuators are widely used in technical fields such as video cameras or pan-tilts. Among them, SMA (shape memory alloys, shape memory alloy) material is set as another feasible actuator due to its heat-shrinking property, and can meet the requirement of miniaturization. When in use, the SMA driver is heated to drive it to move, and then according to the resistivity change of the SMA driver, the displacement control converges until it converges to a preset value. But with this driving method, the displacement control precision is not high.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, a driving method, actuation structure and storage medium of the SMA wire pair are proposed, which can improve the precision of the displacement control of the SMA wire.

In a first aspect, the present application provides a method for driving an SMA line pair, the method comprising:

providing an initial drive signal to the SMA line pair; the SMA line pair includes a first SMA line and a second SMA line;

Acquiring the target feedback amount required for the target displacement of the movable element; wherein, the SMA line pair obtained from the initial drive signal is used to drive the movable element to generate the target displacement;

Obtaining a first feedback amount corresponding to a change in strain of the first SMA wire and a second feedback amount corresponding to a change in strain of the second SMA wire;

According to the target feedback amount, the first feedback amount, and the second feedback amount, continuously increase the driving signal to the first SMA line with a first increment, and send a driving signal to the second SMA line with a first decrement The line continuously decreases the driving signal; wherein, the difference between the first increment and the first decrement is equal to a preset threshold value.

In a second aspect, the present application also provides an actuation structure, including:

SMA wire pair, the SMA wire pair includes a first SMA wire and a second SMA wire;

There are four fixing structures, and the four fixing structures are respectively used to fix both ends of the first SMA wire and the second SMA wire;

A movable element, the movable element is movably connected with the first SMA wire and the second SMA wire; the movable element generates a target displacement through the first SMA wire and the second SMA wire;

A detection module, the detection module is used to obtain in real time a first feedback amount corresponding to a change in the strain of the first SMA wire and a second feedback amount corresponding to a change in the strain of the second SMA wire;

A control processing module, the control processing module is electrically connected to the first SMA line, the second SMA line, and the detection module, and the control module is used to execute the SMA line pair described in any one of the first aspect drive method.

In a third aspect, the present application further provides a storage medium, including computer-executable instructions stored therein, and the computer-executable instructions are used to execute the method for driving an SMA wire pair according to any one of the first aspect.

According to the above-mentioned embodiment of the present application, it has at least the following beneficial effects: by setting the initial driving signal, the subsequent first SMA line and the second SMA line are driven by the driving signal, and the strain energy generated by them can be estimated more accurately. Estimated target feedback volume for . At the same time, by simultaneously providing corresponding drive signals to the first SMA wire and the second SMA wire of the SMA wire pair, the first SMA wire is tightened by a preset distance while the second SMA wire is stretched by a preset distance , so that the movement of the target displacement can be carried out under the joint action of the SMA wire pair. Compared with the control of a single SMA wire or the control of different driving signals of the SMA wire pair, the displacement accuracy obtained by the driving method of the present application is higher.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

1 is a schematic flow diagram of a driving method for an SMA line pair according to an embodiment of the present invention;

FIG. 2 is a schematic flowchart of step S400 in a method for driving an SMA line pair according to an embodiment of the present invention;

FIG. 3 is a schematic flowchart of step S400 in a method for driving an SMA line pair according to another embodiment of the present invention;

Fig. 4 is a schematic diagram of an actuating structure of an embodiment of the embodiment of the present invention;

Fig. 5 is a schematic diagram of an actuating structure of another embodiment of the embodiment of the present invention.

Reference signs:

The first SMA wire 110 , the second SMA wire 120 , the fixed structure 200 , the movable element 300 .

detailed description

Embodiments of the present application are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary, and are only for explaining the present application, and should not be construed as limiting the present application.

In the description of the present application, greater than, less than, exceeding, etc. are understood as not including the original number, and above, below, within, etc. are understood as including the original number. If the description of the first and second is only for the purpose of distinguishing the technical features, it cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features relation. It should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc. indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the Describe, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and operate in a particular orientation, and thus should not be construed as limiting the application.

In the description of the present invention, unless otherwise clearly defined, words such as setting, installation, and connection should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

The driving method, actuating structure and storage medium of the SMA wire pair of the present application will be described below with reference to FIGS. 1 to 5 .

It can be understood that the present application provides a method for driving an SMA wire pair, the method including:

Step S100 , providing an initial driving signal to the SMA wire pair; wherein, the SMA wire pair includes a first SMA wire 110 and a second SMA wire 120 .

It should be noted that the material and thickness of the first SMA wire 110 and the second SMA wire 120 are the same, so when receiving the initial driving signal, the first SMA wire 110 and the second SMA wire 120 generate the same strain. It should be noted that when the initial driving signal is received, the movable element 300 is located near the middle of the movable range.

It should be noted that, in some embodiments, the initial driving signal can be selected as a driving signal that causes the strain generated again by the first SMA wire 110 and the second SMA wire 120 to fall within the same linear interval; when the first SMA wire 110, When the strain generated again by the second SMA wire 120 is within the linear range, the target displacement of the movable element 300 can be better converted into parameters related to the first SMA wire 110 and the second SMA wire 120, so that the It is quickly judged whether the movable element 300 has reached the target displacement. In some embodiments, the initial driving signal can be selected to make the strain generated again by the first SMA wire 110 and the second SMA wire 120 become a predictable driving signal. At this time, the first SMA wire 110 and the second SMA wire 120 The resulting strains fall in several different linear intervals.

It should be noted that the initial driving signal can be obtained by continuously adjusting the driving signal provided to the first SMA wire 110 and the second SMA wire 120, and observing the moving position of the movable element 300, so that when the movable element 300 is located near the middle position, output drive signal.

Step S200 , acquiring the target feedback amount required for moving the target displacement of the movable element 300 ; wherein, the SMA line pair obtained from the initial driving signal is used to drive the movable element to generate the target displacement.

It should be noted that the target feedback amount is the first SMA line 110, and the second SMA line 120 is the difference between the initial position feedback difference and the target position feedback difference, wherein the initial position feedback difference is The target position feedback difference is the difference between the strain parameters corresponding to the first SMA wire 110 and the second SMA wire 120 after the movable element 300 reaches the target displacement.

Step S300 , acquiring a first feedback amount corresponding to a change in strain of the first SMA wire 110 and a second feedback amount corresponding to a change in strain of the second SMA wire 120 .

It should be noted that the movement of the movable element 300 is not completed in one adjustment, so after each adjustment, it is necessary to detect the parameters corresponding to the strain of the first SMA wire 110 and the second SMA wire 120 (such as temperature, resistance, voltage, etc.), That is, the first feedback amount and the second feedback amount to achieve higher precision displacement control.

Step S400, according to the target feedback amount, the first feedback amount, and the second feedback amount, continuously increase the driving signal to the first SMA wire 110 with a first increment, and continuously decrease the driving signal to the second SMA wire 120 with a first decrement , where the difference between the first increment and the first decrement is equal to a preset threshold value.

It should be noted that, for the first SMA wire 110 and the second SMA wire 120, since the same material or thickness is used, the strain generated by the first SMA wire 110 and the second SMA wire 120 in the same environment is the same, so It can be determined by judging whether the difference between the first feedback amount and the second feedback amount, and the difference between the feedback amount difference corresponding to the first SMA line 110 and the second SMA line 120 at the initial drive signal is equal to or close to the target feedback Quantity to judge whether the target displacement has been moved, so that the common mode interference can be reduced by means of difference. At this time, when the first SMA wire 110 shrinks by Δd under the action of the first incremental driving signal, at the same time, the second SMA wire 120 will stretch by Δd under the action of the first decrementing driving signal; thus, the movable element 300 can move the distance corresponding to Δd. Since the displacement of the movable element 300 is controlled by using two SMA wire pairs with different directions, the displacement control thereof will be more precise.

It should be noted that step S300 needs to be executed once each time the driving signal is increased for the first SMA wire 110 and the driving signal is decreased for the second SMA wire 120, so as to determine whether the target feedback amount and the first feedback amount at the current moment , The second feedback amount continues to provide driving signals to the first SMA wire 110 and the second SMA wire.

It should be noted that the continuous increase or continuous decrease can be controlled by a PID algorithm.

It should be noted that the threshold value can be set according to the actual situation, and can be 0.01 or any value that can allow the displacement error. When the threshold value is 0, that is, when the first increment is equal to the first decrement, the degree of convergence of the displacement adjusted by the above method is the highest, that is, the displacement accuracy is the highest.

Therefore, by setting the initial driving signal, the strain generated by the subsequent first SMA wire 110 and the second SMA wire 120 under the driving signal is within a linear range, thereby more accurately estimating the target feedback amount. At the same time, by simultaneously providing corresponding driving signals to the first SMA wire 110 and the second SMA wire 120 of the SMA wire pair, the first SMA wire 110 is tightened to a preset distance while the second SMA wire 120 is preset. The distance is stretched, so that the target distance can be moved under the joint action of the SMA line pair. Compared with the control of a single SMA line or the control of different driving signals of the SMA line pair, the displacement accuracy obtained by the driving method of this application is higher. .

It can be understood that the driving signal is a pulse width modulation driving signal or a constant current driving signal.

It can be understood that the target feedback amount is one of temperature difference, voltage reciprocal difference, and resistance difference.

It can be understood that if the target feedback amount is a temperature difference, as shown in Figure 2, step S400 includes:

Step S510, obtaining the first temperature difference between the first initial temperature of the first SMA wire 110 and the second initial temperature of the second SMA wire 120; wherein, the first initial temperature and the second initial temperature respectively correspond to the first SMA wire 110 , the temperature value when the second SMA wire 120 provides the initial driving signal.

Step S520, acquiring a second temperature difference between the first feedback amount and the second feedback amount.

It should be noted that the first feedback amount is the temperature value obtained in real time by the first SMA wire 110 at the current moment. The second feedback amount is the temperature value acquired by the second SMA wire 120 in real time at the current moment. The first feedback amount and the second feedback amount can be obtained through temperature detection equipment detection or conversion through resistance, so as to realize quick adjustment.

Step S530 , according to the first temperature difference, the second temperature difference, and the target feedback amount, continuously increase the driving signal to the first SMA wire 110 with a first increment, and continuously decrease the driving signal to the second SMA wire 120 with a first decrement.

It should be noted that, assuming that the difference between the first temperature difference and the second temperature difference is ΔT, when ΔT is equal to the target feedback amount or infinitely approaches the target feedback amount, it can be judged that the movable element has reached the target position.

It can be understood that if the target feedback amount is the voltage reciprocal difference, as shown in Figure 3, step S400 includes:

Step S610, obtaining the first initial voltage difference between the first initial voltage of the sampling resistor of the first SMA line 110 in series and the second initial voltage of the sampling resistor of the second SMA line 120 in series; wherein, the first initial voltage, the second initial The voltages respectively correspond to the voltage values of the corresponding series resistors when initial driving signals are provided to the first SMA wire 110 and the second SMA wire 120 .

It should be noted that, assuming that the first initial voltage is V ₁ and the second initial voltage is V ₂ , then the first voltage reciprocal difference is

Step S620, acquiring the second reciprocal voltage difference between the first feedback amount and the second feedback amount.

It should be noted that both the first SMA wire 110 and the second SMA wire 120 are connected in series with a sampling resistor to form an SMA circuit. The first feedback amount is a voltage value of the sampling resistor connected in series with the first SMA line 110 detected in real time. The second feedback amount is the real-time detected voltage value of the sampling resistor connected in series with the second SMA line 120 . Since the power supply voltage provided to the SMA circuit and the resistance value of the sampling resistor are constant, it can be inferred that the reciprocal of the temperature T generated by the first SMA line 110 and the second SMA line 120 and the voltage V _s of the sampling resistor

It has a certain linear relationship, that is, the change of the reciprocal voltage of the sampling resistor corresponds to the temperature change of the SMA line pair, that is,

Therefore, when it is necessary to detect the strain of the first SMA line 110 and the second SMA line 120, it is only necessary to detect the voltage value of the corresponding sampling resistor (that is, the first feedback amount and the second feedback amount) and then simply convert the detection results. , without the need to install a position sensor, thereby saving space, and no longer need to detect the resistance of the first SMA line 110 and the second SMA line 120, thereby saving the amount of calculation of the processor, realizing the rapid adjustment of the driving signal of the SMA line pair, and finally Increase the speed of anti-shake movement. Specifically, the first feedback amount is recorded as V′ ₁ , and the second feedback amount is recorded as V′ ₂ , then the second reciprocal difference is

Step S630, according to the first reciprocal voltage difference, the second reciprocal voltage difference, and the target feedback amount, continuously increase the driving signal to the first SMA wire 110 with the first increment, and at the same time continuously increase the driving signal to the second SMA wire 120 with the first decrement Reduce drive signal.

It can be understood that the present application also provides an actuation structure, as shown in Figures 4 to 5, the actuation structure includes:

SMA wire pair, the SMA wire pair includes a first SMA wire 110 and a second SMA wire 120;

There are four fixing structures 200, and the four fixing structures 200 are respectively used to fix the two ends of the first SMA wire 110 and the second SMA wire 120;

The movable element 300 is movably connected with the first SMA wire 110 and the second SMA wire 120; the movable element 300 generates a target displacement through the first SMA wire 110 and the second SMA wire 120;

The detection module, the acquisition module is used to detect the first feedback amount corresponding to the change of the strain of the first SMA wire 110, and the second feedback amount corresponding to the change of the strain of the second SMA wire 120;

A control processing module, the control processing module is electrically connected to the first SMA wire 110, the second SMA wire 120, and the detection module, and the control module is used to execute any one of the driving methods of the above SMA wire pair.

Wherein, the detection module and the control processing module are not shown in the figure.

It can be understood that the present application also provides a storage medium, including storing computer-executable instructions, and the computer-executable instructions are used to execute any method for driving an SMA wire pair as described above.

For clarification, the term storage medium includes volatile and nonvolatile, removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. and non-removable media. Storage media including, but not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cartridges, tape, magnetic disk storage or other magnetic storage devices, or available Any other medium that stores desired information and can be accessed by a computer.

The driving method of the SMA wire of the actuation structure of the present application will be described in detail in a specific embodiment below with reference to FIGS. 1 to 4 . It should be understood that the following description is only an illustration, rather than a specific limitation on the present application.

Taking the actuation structure shown in FIG. 4 as an example, the control of the SMA wire pair is performed in the following manner.

As shown in FIG. 1 , first refer to step S100 ; the control processing module provides initial driving signals to the first SMA wire 110 and the second SMA wire 120 respectively. Wherein, the initial driving signal ensures that the strain generated again by the first SMA wire 110 and the second SMA wire 120 is within a linear range.

When the movable element 300 needs to move a preset distance (i.e. target position) ΔD, the target feedback amount in step S200 is obtained through the relationship between ΔD and the Δd distance moved by the first SMA wire 110 and the second SMA wire 120 .

Further, referring to step S300 , the first feedback amount corresponding to the strain of the first SMA wire 110 and the second feedback amount corresponding to the strain of the second SMA wire 120 are detected.

Further, referring to step S400, according to the target feedback amount, the first feedback amount, and the second feedback amount, continuously increase the constant current drive signal to the first SMA line 110, and correspondingly reduce the same constant current drive signal to the second SMA line 120.

Specifically, assuming that the target feedback amount is a temperature difference, refer to step S510 to step S530 to move the movable element 300 by a preset distance ΔD.

Assuming that the constant current drive signal is ΔI, the first initial temperature is

The second initial temperature is

The first feedback amount at time t2 is

The second feedback quantity is

Then the first temperature difference corresponding to the initial drive signal

The second temperature difference at time _t2

At this time, according to the preset temperature relationship between ΔD and the first SMA wire 110 , the target feedback amount ΔT can be obtained (that is, the first SMA wire 110 needs to shrink, and the second SMA wire 120 needs to stretch). When ΔT'=ΔT' ₂ -ΔT' ₁ and ΔT meet the threshold value, that is, when ΔT' is infinitely close to ΔT, adjust the increment of the constant current drive signal ΔI to the first SMA line 110, and adjust to the second SMA line 120 Decrease the constant current driving signal ΔI so that the distance difference between the first SMA wire 110 , the second SMA wire 120 and the target displacement is kept within a preset threshold value.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "exemplary embodiments", "which can be understood to" and the like mean that specific features, structures, or structures are described in connection with the embodiment or example. , material or feature is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and can also be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the technical field. Variations.

Claims

A method for driving an SMA line pair, characterized in that the method comprises:

providing an initial drive signal to the SMA line pair; the SMA line pair includes a first SMA line and a second SMA line;

Acquiring the target feedback amount required for the target displacement of the movable element; wherein, the SMA line pair obtained from the initial drive signal is used to drive the movable element to generate the target displacement;

Obtaining a first feedback amount corresponding to a change in strain of the first SMA wire and a second feedback amount corresponding to a change in strain of the second SMA wire;

According to the target feedback amount, the first feedback amount, and the second feedback amount, continuously increase the driving signal to the first SMA wire with a first increment and send a driving signal to the second SMA wire with a first decrement Continuously reducing the driving signal; wherein, the difference between the first increment and the first decrement satisfies a preset threshold value.
The driving method of the SMA wire pair according to claim 1, wherein,

The driving signal is a pulse width modulation driving signal or a constant current driving signal.
The driving method of the SMA wire pair according to claim 1, wherein,

The target feedback amount is one of temperature difference, voltage reciprocal difference, and resistance difference.
The driving method of the SMA line pair according to claim 3, wherein,

If the target feedback amount is a temperature difference, then according to the target feedback amount, the first feedback amount, and the second feedback amount, continuously increase the driving signal to the first SMA line with a first increment and continuously reducing the drive signal to the second SMA line by a first decrement; comprising:

Obtaining the first temperature difference between the first initial temperature of the first SMA wire and the second initial temperature of the second SMA wire; wherein the first initial temperature and the second initial temperature respectively correspond to the first A SMA line, the temperature value when the second SMA line provides the initial drive signal;

acquiring a second temperature difference between the first feedback quantity and the second feedback quantity;

According to the first temperature difference, the second temperature difference, and the target feedback amount, continuously increase the driving signal to the first SMA line with a first increment, and at the same time, give the second SMA line a first decrement. line continuously reduces the drive signal.
The driving method of the SMA line pair according to claim 3, wherein,

If the target feedback amount is a voltage reciprocal difference, then according to the target feedback amount, the first feedback amount, and the second feedback amount, continuously increase the driving of the first SMA line with a first increment signal and continuously reduce the drive signal to the second SMA wire by a first decrement; comprising:

Obtaining the first reciprocal voltage difference between the first initial voltage of the sampling resistor connected in series with the first SMA line and the second initial voltage of the sampling resistor connected in series with the second SMA line, wherein the first initial voltage, the The second initial voltage respectively corresponds to the voltage value of the corresponding sampling resistor when the initial driving signal is provided to the first SMA line and the second SMA line;

Acquiring a second reciprocal voltage difference between the first feedback quantity and the second feedback quantity;

According to the first reciprocal voltage difference, the second reciprocal voltage difference, and the target feedback amount, continuously increase the driving signal to the first SMA line with a first increment, and at the same time give the first decrement to the The second SMA line continues to reduce the drive signal.
An actuation structure, characterized in that it comprises:

SMA wire pair, the SMA wire pair includes a first SMA wire and a second SMA wire;

There are four fixing structures, and the four fixing structures are respectively used to fix both ends of the first SMA wire and the second SMA wire;

A movable element, the movable element is movably connected with the first SMA wire and the second SMA wire; the movable element generates a target displacement through the first SMA wire and the second SMA wire;

A detection module, the detection module is used to obtain the first feedback amount corresponding to the change of the strain of the first SMA wire and the second feedback amount corresponding to the change of the strain of the second SMA wire;

A control processing module, the control processing module is electrically connected to the first SMA wire, the second SMA wire, and the detection module, and the control module is used to execute the SMA according to any one of claims 1 to 5 The driving method of the line pair.
A storage medium, characterized in that it includes computer-executable instructions stored therein, and the computer-executable instructions are used to execute the method for driving the SMA wire pair according to any one of claims 1 to 5.