Electrified memory alloy wire pulse driving and resistance monitoring integrated device

Abstract

An electrified memory alloy wire pulse driving and resistance monitoring integrated device is mainly composed of a PWM signal generator, a relay, an instrument high-precision amplifier, a power amplification board, a high-precision standard resistor and an external power source. The device can carry out pulse driving on the SMA wire in a time period when the PWM signal generator outputs a high level and carry out resistance monitoring on the SMA wire in a time period when the PWM signal generator outputs a low level, the duty ratio of a signal output by each PWM signal output channel can be independently adjusted, the frequency can be uniformly adjusted, and the device is simple in structure and convenient to operate. Therefore, the whole device can realize more accurate pulse driving and resistance monitoring on the SMA wire; the driving capability of the device to the SMA wire can be changed by adjusting the frequency and the duty ratio of the PWM signal, so that the shrinkage displacement and the internal stress of the SMA wire are changed, and the relation between the resistance of the SMA wire and the stress and the strain can be obtained after the shrinkage displacement and the internal stress change condition of the SMA wire and the resistance change condition of the SMA wire are subjected to joint analysis respectively; therefore, the phase change state of the SMA wire can be sensed through the resistance of the SMA wire.

Description

Technical Field

[0001] The invention relates to an integrated device for pulse driving and resistance monitoring of an energized memory alloy wire, belonging to the technical field of intelligent materials and devices. Background Art

[0002] Shape memory alloy (SMA) is a smart material with unique shape memory effect and superelastic properties. When SMA is heated above a critical temperature, it can return to its previous shape, and when cooled it returns to its deformed state. This material is mainly made of nickel-titanium alloy and is widely used in aerospace, medical equipment, micro-drive devices and other fields. The advantage of shape memory alloy is that it can produce large stress and strain, has the advantages of high energy density and light weight. However, how to accurately control its phase change and response time has become a key challenge for its large-scale application.

[0003] SMA needs to be heated to activate its shape memory effect so that its internal crystal phase undergoes a phase change, but the traditional driving method is inefficient and slow to respond, and is not suitable for precision control. With the increasing demand for high-precision and fast-response driving devices, pulse driving technology has gradually become an effective method. By controlling the pulse voltage, SMA can be quickly heated to cause its internal crystal phase to undergo a phase change, while reducing energy consumption and increasing the response speed. However, it is difficult to accurately control the phase change process of SMA by pulse driving alone, because the temperature distribution of SMA is not always uniform, resulting in different degrees of phase change in different parts of SMA. Therefore, the driving device needs to provide real-time feedback on the phase change of SMA to ensure the stability and controllability of the driving process. In addition, during the heating process of SMA, its resistance will change significantly with the change of temperature. Using resistance monitoring technology, the resistance change of SMA can be tracked in real time. This technology can not only be used to detect whether SMA has completely phase-changed, but also can be used in feedback control systems to adjust the driving current according to the real-time resistance value to avoid overheating or incomplete phase change.

[0004] In summary, with the increasing demand for micro-devices and precision mechanical control, faster, low-power and precise SMA drive devices are needed. At the same time, in order to improve the reliability and performance of SMA drives, the monitoring and driving functions must be integrated. The technical background of the integrated device of pulse drive and resistance monitoring of energized memory alloy wire comes from the development of shape memory alloy materials, and combines pulse drive and resistance monitoring technology to improve the response speed, control accuracy and energy efficiency of the SMA drive system. The demand for this technical background has prompted the extensive research and application of this device in multiple high-precision application fields. Summary of the invention

[0005] The purpose of the present invention is to provide an integrated device for pulse driving and resistance monitoring of energized memory alloy wire. The high level of the rectangular wave pulse voltage output by the PWM signal generator is input to the signal input end of the power amplifier board, thereby controlling the signal output end of the power amplifier board to output voltage to the SMA wire, thereby realizing pulse driving of the SMA wire. When the PWM signal generator outputs a low level, the instrument uses a high-precision amplifier to monitor the resistance of the SMA wire. The pulse signal output by the PWM signal generator controls the action and reset of the relay, thereby controlling the on-off of the circuit, so that the entire device can alternately perform pulse driving and resistance monitoring on the SMA wire, and the duty cycle of the signal output by each PWM signal output channel can be adjusted independently, and the frequency can be adjusted uniformly, so that the entire device can achieve more accurate pulse driving and resistance monitoring on the SMA wire. Since adjusting the frequency and duty cycle of the PWM signal can change the driving ability of the device to the SMA wire, thereby changing the contraction displacement and internal stress of the SMA wire, the contraction displacement and internal stress changes of the SMA wire are respectively analyzed in conjunction with the resistance changes of the SMA wire, and the relationship between the resistance of the SMA wire and the stress and strain can be obtained, so that the phase change state of the SMA wire can be sensed through the resistance of the SMA wire. The frequency and duty cycle of the pulse voltage for pulse driving the SMA wire are consistent with the frequency and duty cycle of the pulse voltage output by the PWM signal generator. In addition, the external power supply of the power amplifier board is also the power supply for the SMA wire, so the high level of the pulse voltage for pulse driving the SMA wire is equal to the output voltage of the external power supply of the power amplifier board.

[0006] The present invention is achieved through the following technical solutions:

[0007] An integrated device for pulse driving and resistance monitoring of energized memory alloy wire mainly consists of a PWM signal generator, a relay, a high-precision amplifier for instruments, a power amplifier board, a high-precision standard resistor, and an external power supply. The signal output end of the PWM signal generator and the output power supply end of the high-precision amplifier for instruments are connected to the relay in a specific wiring method, and then the relay is connected to the signal input end and SMA wire of the power amplifier board in a corresponding wiring method, and finally the signal output end of the power amplifier board is connected to the SMA wire. In this process, a signal output end of the PWM signal generator corresponds to a signal input end and a signal output end of the power amplifier board, and is used in conjunction with a relay and a high-precision amplifier for instruments. The relay controls the on and off of the circuit, so that the entire device can alternately perform pulse driving and resistance monitoring on the SMA wire.

[0008] The advantages of the present invention are: the device can perform pulse driving on the SMA wire in the time period when the PWM signal generator outputs a high level, and monitor the resistance of the SMA wire in the time period when the PWM signal generator outputs a low level, so that the entire device can alternately perform pulse driving and resistance monitoring on the SMA wire, and the duty cycle of the signal output by each PWM signal output channel can be adjusted independently, and the frequency can be adjusted uniformly, so that the entire device can achieve more accurate pulse driving and resistance monitoring on the SMA wire; the entire device has high integration, small size, low cost, and good scalability, which makes it possible for large-scale SMA pulse driving and resistance monitoring, and the pulse voltage can be quickly Heating the SMA wire can reduce energy consumption and improve response speed compared with traditional driving methods; in addition, the resistance monitoring technology of the device can track the resistance change of the SMA in real time. After adding a feedback control system, the frequency and duty cycle can be adjusted according to the real-time resistance value to avoid overheating or incomplete phase change of the SMA wire; in addition, the external power supply of the power amplifier board is also the power supply for the SMA wire, so the high level of the pulse voltage for pulse driving the SMA wire is equal to the output voltage of the external power supply of the power amplifier board, so the corresponding external power supply can be selected according to the actual situation, so as to drive the SMA wire more safely to avoid burning the SMA wire due to excessive voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of the integrated device for pulse driving and resistance monitoring of energized memory alloy wire

[0010] Figure 2 Schematic diagram of external pins of PWM signal generator

[0011] Figure 3 Schematic diagram of external pins of high-precision amplifier for instrument

[0012] Figure 4 Schematic diagram of the external pins of a mechanical relay

[0013] Figure 5 Schematic diagram of external pins of the power amplifier board

[0014] Figure 6 Schematic diagram of the output waveform of the PWM signal generator

[0015] Figure 7 Schematic diagram of the operation flow of the integrated device for pulse driving and resistance monitoring of energized memory alloy wire DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings.

[0017] refer to Figure 1The present invention provides an integrated device for pulse driving and resistance monitoring of an energized memory alloy wire, which is mainly composed of a PWM signal generator, a relay, a high-precision amplifier for instruments, a power amplifier board, a high-precision standard resistor, and an external power supply. The device can pulse drive the SMA wire during the time period when the PWM signal generator outputs a high level, and monitor the resistance of the SMA wire during the time period when the PWM signal generator outputs a low level, so that the entire device can alternately perform pulse driving and resistance monitoring on the SMA wire.

[0018] refer to Figure 2 , take the PWM signal generator with two signal output terminals as an example, the V+ and GND on it are the positive and negative poles of the external power supply respectively. A and B are 485 communication interfaces. After connecting to the USB interface of the computer through the USB to 485 adapter, the frequency and duty cycle of the PWM pulse signal can be adjusted on the computer through the relevant control program. VCOM is the PWM signal output power supply terminal, V5+ is the +5V power supply output by the module, P1 and P2 are the negative poles of the PWM signal output terminal. When using, VCOM and V5+ need to be connected together to achieve the purpose of the high level of the PWM signal output from the PWM signal output terminal being 5V.

[0019] refer to Figure 3 , the +5V and GND of the instrument high-precision amplifier are the positive and negative poles of the external 5V power supply respectively. E+ and E- are the output power supply terminals, and S+ and S- are the source input amplifier terminals. OUT is the positive pole of the signal output terminal, and the negative pole of the external power supply is also the negative pole of the signal output terminal. In addition, the E+, E- terminals and the S+, S- terminals will be connected to an external bridge, the purpose of which is to increase the resistance measurement range of the instrument high-precision amplifier. Three of the four arms of the bridge are three high-precision standard resistors, and the other arm is a high-precision standard resistor and SMA wire in series. When the instrument high-precision amplifier is working, the E+ and E- terminals will output a small current to the bridge, and then the internal circuit of the instrument high-precision amplifier will receive the voltage at the S+ and S- terminals and amplify it, and at the same time transmit the amplified signal to the signal output terminal. After using the data acquisition card to collect the voltage signal at the signal output terminal, the collected data is substituted into the relevant conversion and calibration formula to obtain the true resistance value of the SMA wire.

[0020] refer to Figure 4 The "+" and "-" of the mechanical relay are the positive and negative poles of the external power supply, and its rated working voltage is 5V. The other 6 contacts are 2 groups of normally open contacts and 2 groups of normally closed contacts. These 4 groups of contacts share 2 moving contacts. The 2 contacts close to the external power supply side of the relay are the static contacts in the 2 groups of normally closed contacts, and the 2 contacts far from the external power supply side of the relay are the static contacts in the 2 groups of normally open contacts.

[0021] refer to Figure 5Take the power amplifier board with two signal input terminals and two signal output terminals as an example. The VCC and GND on it are the positive and negative poles of the external power supply respectively. VCC is also the positive pole for powering the SMA wire. o1 and o2 are the signal output terminals, which are the negative poles for powering the SMA wire. COM is the signal input common terminal, which is the positive pole, and 1 and 2 are the negative poles of the signal input terminals.

[0022] refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 When wiring, for the pulse drive circuit, first connect the VCOM and V5+ on the PWM signal generator together, then connect the two to the COM terminal of the power amplifier board, the positive poles of relay 1 and relay 2, then connect P1 on the PWM signal generator to the negative pole of relay 1 and the moving contact on the negative side of it, connect P2 to the negative pole of relay 2 and the moving contact on the negative side of it, then connect the static contacts in a group of normally open contacts on the negative side of relay 1 and relay 2 to the signal input terminals 1 and 2 of the power amplifier board respectively, finally connect the VCC on the power amplifier board to one end of the two SMA wires, o1 to the other end of SMA wire 1, and o2 to the other end of SMA wire 2. For the circuit of the resistance monitoring part, first connect the four high-precision standard resistors R1, R2, R3, and R4 in series with their ends connected to each other, then disconnect R2 and R3, and then connect the E+ of the instrument's high-precision amplifier between R1 and R4, S- between R1 and R2, S+ between R4 and R3, and E- to the end of R2 away from S-, and then connect the end of R2 away from S- to the end of the two SMA wires connected to the power amplifier board VCC, and then connect the end of R3 away from S+ to the static contact in a group of normally closed contacts on the positive side of the relay power supply, and finally connect the moving contact on the relay to the other end of the SMA wire, so that an electric bridge is connected to the E+, E- ends and the S+, S- ends. Three of the four arms of the bridge are R1, R2, and R4, and the other arm is formed by R3 and the SMA wire in series.

[0023] refer to Figure 1 , Figure 6 , Figure 7, the computer controls the PWM signal generator to output a PWM signal with a high amplitude of about 5V and an adjustable duty cycle and frequency to the external power supply of the relay. Since the rated working voltage of the relay is 5V, during the time period when the PWM signal generator outputs a high level, the relay operates, and the signal output end of the PWM signal generator is connected to the signal input end of the power amplifier board, so that the circuit of the pulse drive part is connected, and the high level is transmitted to the signal input end of the power amplifier board, so that the power amplifier board outputs a pulse voltage to drive the SMA wire. Since the instrument uses a high-precision amplifier to monitor the resistance of the SMA wire only when there is no external power supply, during the time period when the PWM signal generator outputs a low level, the relay is reset, so that the circuit of the resistance monitoring part is connected and the circuit of the pulse drive part is disconnected, so that the instrument uses a high-precision amplifier to monitor the resistance of the SMA wire. To sum up, by controlling the on and off of the relay control circuit, the entire device can realize alternating pulse driving and resistance monitoring of the SMA wire, that is, the SMA wire is pulse driven during the time period when the PWM signal generator outputs a high level, and the resistance of the SMA wire is monitored during the time period when the PWM signal generator outputs a low level.

[0024] The above examples illustrate the technical concept and structural features of the patent of the present invention, with the aim of enabling scientific researchers and engineering technicians conducting research in this field to understand the patent of the present invention and to be able to implement the product accordingly.

Claims

1. An integrated device for pulse driving and resistance monitoring of an energized memory alloy wire, characterized in that: This device for pulse driving and resistance monitoring of energized memory alloy wire consists of six parts, namely, a PWM signal generator, a power amplifier board, a relay, a high-precision amplifier for instruments, a high-precision standard resistor, and an external power supply. The pulse signal output by the PWM signal generator controls the action and reset of the relay, thereby controlling the on and off of the circuit, so that the entire device can realize alternating pulse driving and resistance monitoring of the SMA wire, that is, the SMA wire is pulse driven during the time period when the PWM signal generator outputs a high level, and the resistance of the SMA wire is monitored during the time period when the PWM signal generator outputs a low level, and the duty cycle of the signal output by each PWM signal output channel can be adjusted independently, and the frequency can be adjusted uniformly, so that the entire device can achieve more accurate pulse driving and resistance monitoring of the SMA wire.

2. An integrated device for pulse driving and resistance monitoring of a powered memory alloy wire according to claim 1, characterized in that: During the time period when the PWM signal generator outputs a high level, the relay is activated, and the signal output end of the PWM signal generator is connected to the signal input end of the power amplifier board, thereby connecting the circuit of the pulse drive part, and the high level is transmitted to the signal input end of the power amplifier board, so that the power amplifier board outputs a pulse voltage to drive the SMA wire, and the frequency and duty cycle of the pulse voltage output by the power amplifier board are consistent with the frequency and duty cycle of the pulse voltage output by the PWM signal generator.

3. The device for pulse driving and resistance monitoring of a powered memory alloy wire according to claim 1, characterized in that: Since the instrument's high-precision amplifier can only monitor the resistance of the SMA wire when there is no external power supply, the relay is reset during the period when the PWM signal generator outputs a low level, so that the circuit of the resistance monitoring part is connected and the circuit of the pulse driving part is disconnected, so that the instrument's high-precision amplifier can monitor the resistance of the SMA wire.

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