MEMS small-range pressure dynamic calibration system and method based on piezoelectric actuator

Abstract

The invention relates to the technical field of MEMS sensor detection, in particular to an MEMS small-range pressure dynamic calibration system and method based on a piezoelectric actuator, and the calibration system comprises a simulation piezoelectric controller, a piezoelectric ceramic actuator, a high-precision pull pressure calibration sensor, an MEMS to-be-calibrated sensor detection platform, a lead screw lifting assembly, and an external data collection system. During calibration, the displacement of the piezoelectric ceramic actuator is controlled by simulating a voltage signal input by the piezoelectric controller, so that the piezoelectric ceramic actuator extrudes the MEMS sensor to be calibrated and applies pressure to the MEMS sensor to be calibrated, at the moment, the doped silicon beam of the MEMS sensor to be calibrated deforms, the resistance is changed due to the piezoresistive effect, and the MEMS sensor to be calibrated is calibrated. The external data acquisition system obtains voltage values at the two ends of the MEMS sensor to be calibrated by building a Wheatstone bridge, and then force calibration of the MEMS sensor to be calibrated is achieved. According to the invention, high-precision small-range sensor force calibration can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS sensor detection, and more specifically, to a MEMS small-range pressure dynamic calibration system and method based on a piezoelectric actuator. Background Art

[0002] With the continuous deepening of the participation of robots in human production activities, their human-like attributes have become increasingly obvious. The human-like capabilities of robots are inseparable from a perfect perception system, which can greatly expand the application scope of robots. Through force sensors, robots can perceive the surrounding environment and target objects, and identify the material, texture, roughness, stiffness, etc. of the objects. Traditional sensor force measurement methods usually have some limitations, such as low test accuracy, inability to perform dynamic performance tests, and resonance phenomena. In order to overcome the limitations of traditional sensor force measurement methods, as well as the small full scale of MEMS sensors, high-precision small-range dynamic calibration systems and methods have attracted much attention.

[0003] A piezoelectric ceramic actuator is a device that uses piezoelectric ceramic materials to achieve mechanical motion. It inputs a voltage signal through an electrode, generates deformation, and thus drives a bracket to achieve mechanical motion. Moreover, its displacement change is proportional to the magnitude of the voltage signal input by the controller. The applicant found that by converting the displacement extrusion of the piezoelectric ceramic actuator into an applied force, the magnitude of the applied force can be obtained from a tensile and compressive calibration sensor. The minimum measurement accuracy of the tensile and compressive calibration sensor is 1 mN, which can meet the requirements of high-precision dynamic tests.

[0004] Therefore, the present invention designs a MEMS small-range pressure dynamic calibration system and method based on a piezoelectric actuator, aiming to develop a high-precision dynamic pressure calibration device with high precision, meeting dynamic requirements, and high cost performance. Summary of the Invention

[0005] The object of the present invention is to propose a MEMS small-range pressure dynamic calibration system and method based on a piezoelectric actuator, which can achieve high-precision small-range sensor force calibration to solve the problems raised in the above background art.

[0006] To achieve the above object, the specific technical solutions adopted by the present invention are as follows:

[0007] A MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator, including an aluminum plate base, and further including:

[0008] An analog piezoelectric controller for outputting a voltage signal to the piezoelectric ceramic actuator;

[0009] A piezoelectric ceramic actuator for converting the voltage signal output by the analog piezoelectric controller into displacement, and then converting the displacement into pressure applied to the sensor to be calibrated;

[0010] A high-precision tensile and compressive force calibration sensor is installed at the upper end of the piezoelectric ceramic actuator and is used to measure the pressure exerted by the piezoelectric ceramic actuator on the sensor to be calibrated.

[0011] The MEMS sensor to be calibrated detection platform is used to realize the electrical connection between the MEMS sensor to be calibrated and the PCB pad, and connect the signal input and output ports of the MEMS sensor to be calibrated with an external data acquisition system.

[0012] The lead screw lifting assembly is connected to the high-precision tensile and compressive force calibration sensor through the bracket assembly and the T-shaped adapter, and is used to adjust the distance between the MEMS sensor to be calibrated and the piezoelectric ceramic actuator.

[0013] The external data acquisition system includes a data acquisition circuit and a host computer, and is used to obtain an output voltage proportional to the pressure received by the MEMS sensor to be calibrated through a Wheatstone bridge, and cooperate with the analog piezoelectric controller to complete the force calibration work of the MEMS sensor.

[0014] Further, the piezoelectric ceramic actuator adopts a closed-loop piezoelectric actuator. There is an internal thread at its upper end for connecting the high-precision tensile and compressive force calibration sensor, and displacement output at the lower end. The total stroke is 9μm. The output of the analog piezoelectric controller is 0 - 150V, the bandwidth is 100kHz, the magnitude of the input voltage signal is proportional to the displacement of the actuator, and a sinusoidal voltage signal can be input for dynamic performance testing.

[0015] Further, the high-precision tensile and compressive force calibration sensor adopts a tensile and compressive force calibration sensor with a measurement accuracy of 1mN, including an S-shaped sensor and a control instrument. There are internal threads at both the upper and lower ends of the S-shaped sensor. The upper end is connected to the bracket assembly through a T-shaped adapter, and the lower end is connected to the piezoelectric ceramic actuator through screws. The control instrument is used for data zeroing and peeling operations, and is connected to the host computer through an analog output port to observe the change curve of the force signal.

[0016] Further, the MEMS sensor to be calibrated detection platform includes a PCB pad and a three-axis hand-operated moving table. The PCB pad is installed on the three-axis hand-operated moving table. The three-axis hand-operated moving table includes moving tables in the X, Y, and Z directions. The position of the PCB pad can be finely adjusted through the three-axis hand-operated moving table. During calibration, the MEMS sensor to be calibrated is attached to the exact center of the PCB pad, and wire bonding is performed between the pads of the MEMS sensor to be calibrated and the immersion gold pads on the PCB pad to achieve electrical connection, so that the signal input and output ports of the MEMS sensor to be calibrated can be connected to the external data acquisition circuit.

[0017] Further, the screw lift assembly is mounted on the aluminum plate base through a connecting frame, and includes a screw support frame, a knob, a driving screw, a support rod, a sliding seat and a fixing member. By rotating the knob, the driving screw moves up and down, and then drives the piezoelectric ceramic actuator to perform rough adjustment in the vertical direction through the sliding seat. The sliding seat is connected to the T-shaped adapter through a bracket assembly.

[0018] Further, the Wheatstone bridge uses the doped silicon beam of the MEMS sensor to be calibrated as a variable resistor and an external resistor as a fixed resistor.

[0019] The present invention also provides a method for dynamically calibrating small-range MEMS pressure based on a piezoelectric actuator. This pressure dynamic calibration method uses the above-mentioned MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator to achieve calibration, and includes the following steps:

[0020] S1. Attach the MEMS sensor to be calibrated in the exact middle of the PCB pad, and wire the pad of the MEMS sensor to be calibrated to the immersion gold pad on the PCB pad to achieve electrical connection, so as to connect the signal input and output ports of the MEMS sensor to be calibrated to the external data acquisition circuit;

[0021] S2. Control the displacement of the piezoelectric ceramic actuator by inputting a voltage signal through the analog piezoelectric controller, so that the piezoelectric ceramic actuator squeezes the MEMS sensor to be calibrated and applies pressure to the MEMS sensor to be calibrated. At this time, the magnitude of the applied pressure can be obtained from the tensile and compressive sensor to be calibrated; at the same time, the applied pressure will be transmitted to the doped silicon beam through the elastic structure of the MEMS sensor. After the doped silicon beam is stressed, it deforms, generates a piezoresistive effect, and changes the resistance value of the doped silicon beam. An output voltage proportional to the measured pressure is obtained through an external data acquisition system;

[0022] S3. Gradually increase the voltage signal of the analog piezoelectric controller and repeat step S2 to achieve the calibration of the MEMS sensor to be calibrated.

[0023] The present invention has the following characteristics and beneficial effects:

[0024] 1) The MEMS small-range dynamic pressure calibration system of the present invention applies pressure through the displacement of the piezoelectric ceramic actuator, with high precision, can achieve displacement extrusion at the nanometer level and precision detection at the millinewton level, and meets different pressure requirements by changing the probe shape of the piezoelectric ceramic actuator.

[0025] 2) The MEMS small-range dynamic pressure calibration system of the present invention uses an analog controller to control the piezoelectric actuator. The magnitude of the input voltage signal is proportional to the displacement, and a sinusoidal voltage signal can be input for dynamic performance detection.

[0026] 3) On the basis of meeting high-precision dynamic performance, the MEMS small-range dynamic pressure calibration system of the present invention has a relatively low cost. Compared with the force application scheme using a piezoelectric moving stage, using a piezoelectric ceramic actuator is more cost-effective.

[0027] 4) The MEMS small-range dynamic pressure calibration system and method of the present invention are simple to operate and can be completed by inputting voltage signals and processing data by the host computer. The MEMS sensor to be calibrated can be calibrated through simple operations, and the data can be stored by the host computer. The data can be calibrated by background algorithms to improve the accuracy of the sensor. Description of the Drawings

[0028] Figure 1 It is the overall structure diagram of the MEMS small-range dynamic calibration system;

[0029] Figure 2 It is the schematic structural diagram of the moving lead screw of the calibration system;

[0030] Figure 3 It is the schematic diagram of pressure application of the calibration system;

[0031] Figure 4 It is the schematic structural diagram of the piezoelectric ceramic actuator in the calibration system;

[0032] Figure 5 It is the schematic diagram of the Wheatstone bridge

[0033] Figure 6 It is the schematic diagram of the T-shaped adapter fixing bracket and the calibration sensor;

[0034] In the figure: 1 - aluminum plate base, 2 - connecting frame, 3 - lead screw support frame, 4 - knob, 5 - driving lead screw, 6 - support rod, 7 - sliding seat, 8 - lower L-shaped bracket, 9 - fixing piece, 10 - upper L-shaped bracket, 11 - T-shaped adapter, 12 - tension and compression calibration sensor, 13 - piezoelectric ceramic actuator, 14 - MEMS sensor to be calibrated, 15 - PCB pad, 16 - three-axis hand-operated moving stage, 17 - bottom plate fixing hole, 18 - analog piezoelectric controller, 19 - through slot. Detailed Embodiments

[0035] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] As Figure 1As shown in the figure, a small-range pressure dynamic calibration system for MEMS based on a piezoelectric actuator according to an embodiment of the present invention includes an aluminum plate base 1, an analog piezoelectric controller 18, a piezoelectric ceramic actuator 13, a high-precision tensile and compressive force calibration sensor 12, a MEMS sensor to be calibrated detection platform, a lead screw lifting assembly, and an external data acquisition system. During operation, first, the MEMS sensor to be calibrated is attached to the exact center of the PCB pad, and then wire bonding is performed between the pad of the MEMS sensor to be calibrated and the immersion gold pad on the PCB pad to achieve electrical connection, so that the signal input and output ports of the MEMS sensor to be calibrated are connected to the external data acquisition circuit. Then, as Figure 3 shown in the figure, an input voltage signal is sent through the analog piezoelectric controller 18 to control the displacement of the piezoelectric ceramic actuator 13, so that the piezoelectric ceramic actuator 13 squeezes the MEMS sensor to be calibrated 14 and applies pressure to the MEMS sensor to be calibrated 14. At this time, the doped silicon beam of the MEMS sensor to be calibrated 14 deforms, and the resistance changes due to the piezoresistive effect. The external data acquisition system obtains the voltage value at both ends of the MEMS sensor to be calibrated 14 by building a Wheatstone bridge. Finally, the voltage signal of the analog piezoelectric controller 18 is gradually increased, and the above process of pressure application and measurement is repeated to complete the calibration of the MEMS sensor to be calibrated 14.

[0037] As Figure 4 shown in the figure, the piezoelectric ceramic actuator 13 is connected to the analog piezoelectric controller 18 through a coaxial cable. The analog piezoelectric controller 18 is used to output a voltage signal to the piezoelectric ceramic actuator 13, and the piezoelectric ceramic actuator 13 is used to convert the voltage signal output by the analog piezoelectric controller 18 into displacement, and then convert the displacement into pressure and apply it to the sensor 14 to be calibrated. The piezoelectric ceramic actuator 13 adopts a closed-loop piezoelectric actuator, with piezoelectric ceramics inside and a stainless steel shell outside. The stainless steel shell is divided into an actuating part and an anti-torsion part. There is an internal thread at the upper end of the stainless steel shell for connecting the high-precision tensile and compressive force calibration sensor 12, and a probe for displacement output at the lower end. The shape of the probe can be selected according to requirements. The total stroke of the piezoelectric ceramic actuator 13 is 9μm; the output of the analog piezoelectric controller is 0 - 150V, the bandwidth is 100kHz, the magnitude of the input voltage signal is proportional to the displacement of the actuator, and a sinusoidal voltage signal can be input for dynamic performance testing.

[0038] In this embodiment, the high-precision tensile and compressive force calibration sensor 12 is installed at the upper end of the piezoelectric ceramic actuator 13 and is used to measure the pressure applied by the piezoelectric ceramic actuator 13 on the sensor to be calibrated 14. Specifically, the high-precision tensile and compressive force calibration sensor 12 is a tensile and compressive force calibration sensor with a measurement accuracy of 1 mN, including an S-shaped sensor and a control instrument. Both the upper and lower ends of the S-shaped sensor have internal threads. The upper end is connected to the bracket assembly through a T-shaped adapter 11, and the lower end is connected to the piezoelectric ceramic actuator 13 through screws. The control instrument is used for data zeroing and peeling operations, and is connected to the host computer through an analog output port to observe the change curve of the force signal.

[0039] In this embodiment, the MEMS sensor to be calibrated detection platform is used to realize the electrical connection between the MEMS sensor to be calibrated 14 and the PCB pad, and connect the signal input and output ports of the MEMS sensor to be calibrated to an external data acquisition system. Specifically, the MEMS sensor to be calibrated detection platform includes a PCB pad 15 and a three-axis hand-cranked moving stage 16. The PCB pad 15 is installed on the three-axis hand-cranked moving stage 16. The three-axis hand-cranked moving stage 16 includes moving stages in the X, Y, and Z directions. The position of the PCB pad can be finely adjusted through the three-axis hand-cranked moving stage. During calibration, the MEMS sensor to be calibrated is attached to the exact center of the PCB pad, and wire bonding is performed between the pads of the MEMS sensor to be calibrated and the immersion gold pads on the PCB pad to achieve electrical connection, so that the signal input and output ports of the MEMS sensor to be calibrated can be connected to an external data acquisition circuit, and further enable the data acquisition system (data acquisition circuit and host computer) to perform data acquisition and processing on the MEMS sensor to be calibrated.

[0040] In this embodiment, the lead screw lifting assembly is connected to the high-precision tensile and compressive force calibration sensor 12 through the bracket assembly and the T-shaped adapter 11 and is used to adjust the distance between the MEMS sensor to be calibrated 14 and the piezoelectric ceramic actuator 13. Specifically, the aluminum plate base 1 is fixed on the optical platform through the bottom plate fixing hole 17. The lead screw lifting assembly is installed on the aluminum plate base 1 through the connecting frame 2. There are multiple internal threaded holes on the aluminum plate base 1 for fixing the connecting frame 2. The lower end of the connecting frame 2 is fixed on the aluminum plate base 1, and the right end is connected and fixed to the lead screw lifting assembly. As Figure 2As shown in the figure, the screw lifting assembly includes a screw support frame 3, a knob 4, a driving screw 5, a support rod 6, a sliding seat 7 and a fixing member 9. The screw support frame 3, the support rod 6 and the fixing member 9 are used to support the moving screw and fix the moving screw to prevent it from shaking. By rotating the knob 4, the driving screw 5 moves up and down, and then drives the piezoelectric ceramic actuator 13 to perform a rough adjustment in the vertical direction through the sliding seat 7. The bracket assembly is composed of a lower L-shaped bracket 8 and an upper L-shaped bracket 10. The lower L-shaped bracket 8 and the upper L-shaped bracket 10 are connected up and down by bolts in the opposite direction. Among them, the lower L-shaped bracket 8 is connected to the sliding seat, and the upper L-shaped bracket 10 is connected to the high-precision tensile and compressive force calibration sensor 12 through a T-shaped adapter 11.

[0041] The external data acquisition system, including a data acquisition circuit and a host computer, is used to obtain an output voltage proportional to the pressure received by the MEMS sensor to be calibrated through a Wheatstone bridge, and cooperate with the analog piezoelectric controller 18 to complete the force calibration work of the MEMS sensor. Specifically, as Figure 5 shown, the Wheatstone bridge consists of four bridge arms. Generally, there is a resistor on one bridge arm. Taking the doped silicon beam of the MEMS sensor to be calibrated 14 as the variable resistor and the external resistor as the fixed resistor. Among them, U is the power supply voltage of the bridge, and U0 is the output voltage of the bridge. Then:

[0042]

[0043] Among them, R3 and R4 are doped silicon variable resistors, and R1 and R2 are fixed resistors. When pressure is applied, the resistance value of one variable resistor increases by ΔR, and the resistance value of the other variable resistor decreases by △R. Assuming R1 = R2 = R3 = R4 = R, we get

[0044] Gradually increase the voltage signal of the analog piezoelectric controller 18. The applied force continuously increases, the deformation of the doped silicon increases, and the voltage value at both ends of the bridge also increases. The force calibration work of the MEMS sensor is completed by this method.

[0045] Figure 6 It is a schematic diagram of the upper L-shaped bracket, the T-shaped adapter and the calibration sensor. It is fixed to the inner thread on the bracket 2 through the through grooves 19 at both ends of the T-shaped adapter 11, and the tensile and compressive force calibration sensor 12 is fixed through the through groove 19 in the middle of the T-shaped adapter 11.

[0046] The working principle of this specific implementation is as follows: By simulating the input voltage signal of the piezoelectric controller 18 to control the displacement of the piezoelectric ceramic actuator 13, the piezoelectric ceramic actuator 13 squeezes the MEMS sensor to be calibrated 14, applying pressure to the MEMS sensor to be calibrated 14. The magnitude of the applied pressure can be obtained from the tensile and compressive force sensor to be calibrated 12. At the same time, the applied pressure is transmitted to the doped silicon beam through the elastic structure of the MEMS sensor to be calibrated, causing the doped silicon to deform under the action of force and generate a piezoresistive effect. The resistance value of the doped silicon changes. The doped silicon serves as a variable resistor, and the external resistor serves as a fixed resistor. When connected into a Wheatstone bridge, an output voltage proportional to the measured pressure can be obtained, thereby achieving the purpose of measurement.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator, including an aluminum plate base, characterized in that: It further includes: A simulated piezoelectric controller for outputting a voltage signal to a piezoelectric ceramic actuator; A piezoelectric ceramic actuator for converting the voltage signal output by the simulated piezoelectric controller into displacement, and then converting the displacement into pressure applied to the sensor to be calibrated; A high-precision tension and compression calibration sensor installed at the upper end of the piezoelectric ceramic actuator for measuring the pressure applied by the piezoelectric ceramic actuator to the sensor to be calibrated; A MEMS sensor to be calibrated detection platform for realizing the electrical connection between the MEMS sensor to be calibrated and the PCB pad, and connecting the signal input and output ports of the MEMS sensor to be calibrated with an external data acquisition system; A lead screw lifting assembly connected to the high-precision tension and compression calibration sensor through a bracket assembly and a T-shaped adapter for adjusting the distance between the MEMS sensor to be calibrated and the piezoelectric ceramic actuator; An external data acquisition system including a data acquisition circuit and a host computer for obtaining an output voltage proportional to the pressure received by the MEMS sensor to be calibrated through a Wheatstone bridge, and cooperating with the simulated piezoelectric controller to complete the force calibration work of the MEMS sensor.

2. The MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator according to claim 1, wherein: The piezoelectric ceramic actuator adopts a closed-loop piezoelectric actuator, which has internal threads at the upper end for connecting the high-precision tension and compression calibration sensor, and outputs displacement at the lower end, with a total stroke of 9μm; the output of the simulated piezoelectric controller is 0-150V, the bandwidth is 100kHz, the magnitude of the input voltage signal is proportional to the displacement of the actuator, and a sinusoidal voltage signal can be input for dynamic performance testing.

3. The MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator according to claim 1, characterized in that: The high-precision tension and compression calibration sensor adopts a tension and compression calibration sensor with a measurement accuracy of 1mN, including an S-shaped sensor and a control instrument. Both the upper and lower ends of the S-shaped sensor have internal threads. The upper end is connected to the bracket assembly through a T-shaped adapter, and the lower end is connected to the piezoelectric ceramic actuator through screws. The control instrument is used for data zeroing and peeling operations, and is connected to the host computer through an analog output port to observe the change curve of the force signal.

4. The MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator according to claim 1, characterized in that: The MEMS sensor to be calibrated detection platform includes a PCB pad and a three-axis hand-operated moving stage. The PCB pad is installed on the three-axis hand-operated moving stage. The three-axis hand-operated moving stage includes moving stages in the X, Y, and Z directions. The position of the PCB pad can be finely adjusted through the three-axis hand-operated moving stage; during calibration, the MEMS sensor to be calibrated is attached to the exact center of the PCB pad, and wire bonding is performed between the pads of the MEMS sensor to be calibrated and the immersion gold pads on the PCB pad to achieve electrical connection, so that the signal input and output ports of the MEMS sensor to be calibrated can be connected to the external data acquisition circuit.

5. The MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator according to claim 1, wherein: The lead screw lifting assembly is installed on an aluminum plate base through a connecting frame, and includes a lead screw support frame, a knob, a driving lead screw, a support rod, a sliding seat, and a fixing member. By rotating the knob, the driving lead screw moves up and down, and then drives the piezoelectric ceramic actuator to perform rough adjustment in the vertical direction through the sliding seat. The sliding seat is connected to the T-shaped adapter through a bracket assembly.

6. The MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator according to claim 1, characterized in that: The Wheatstone bridge uses the doped silicon beam of the MEMS sensor to be calibrated as a variable resistor and an external resistor as a fixed resistor.

7. A MEMS small-range pressure dynamic calibration method based on a piezoelectric actuator, characterized in that: Calibration is achieved by using the MEMS small-range pressure dynamic calibration system based on a piezoelectric actuator according to any one of claims 1-6.

8. A small-range pressure dynamic calibration method for MEMS based on a piezoelectric actuator according to claim 7, characterized in that: The steps are as follows: S1. Attach the MEMS sensor to be calibrated in the exact middle of the PCB pad. Wire bond the pads of the MEMS sensor to be calibrated to the immersion gold pads on the PCB pad to achieve electrical connection, thus connecting the signal input and output ports of the MEMS sensor to be calibrated to the external data acquisition circuit; S2. Input a voltage signal through the analog piezoelectric controller to control the displacement of the piezoelectric ceramic actuator, so that the piezoelectric ceramic actuator squeezes the MEMS sensor to be calibrated and applies pressure to the MEMS sensor to be calibrated. At this time, the magnitude of the applied pressure can be obtained from the tensile and compressive force sensor to be calibrated; at the same time, the applied pressure will be transmitted to the doped silicon beam through the elastic structure of the MEMS sensor, causing the resistance value of the doped silicon beam to change, and an output voltage proportional to the measured pressure can be obtained through the external data acquisition system; S3. Gradually increase the voltage signal of the analog piezoelectric controller and repeat step S2 to achieve the calibration of the MEMS sensor to be calibrated.

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