A Method, System for Suppressing Zero-Bias Temperature Drift of MEMS Gyroscope and MEMS Gyroscope

Abstract

The present invention belongs to the technical field of MEMS gyro correction, and relates to a method and system for suppressing the zero-bias temperature drift of an MEMS gyro and an MEMS gyroscope. A perturbation signal is injected into the sensitive mode feedback signal to obtain a sensitive mode perturbation signal, a Coriolis output, and a quadrature output; the quadrature signal of the perturbation signal and the phase control quantity output by the PI controller are phase-synthesized to output a phase-synthesized signal; the phase-synthesized signal is used to quadrature demodulate and filter the sensitive mode perturbation signal to obtain a filtered signal; the filtered signal is input into the PI controller to output a new phase control quantity to compensate the phases of the Coriolis output and the quadrature output. Based on the compensated quadrature output and Coriolis output, a new sensitive mode feedback signal is obtained until the filtered signal is 0. The PI controller outputs a target phase control quantity based on the filtered signal to compensate the quadrature output and the Coriolis output to obtain a target quadrature output and a target Coriolis output. The present application effectively suppresses the influence of zero-bias temperature drift on the measurement result.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS gyro correction, in particular to a method and system for suppressing zero bias temperature drift of MEMS gyro and an MEMS gyroscope. Background Art

[0002] An MEMS gyroscope is an inertial instrument used to measure the motion angle or angular velocity of an object relative to an inertial space, and is used to realize the measurement and control of the attitude and trajectory of a moving object, and has wide applications in the fields of consumer electronics, aerospace, navigation, and industry. Its speed detection principle is as follows: when the mass block in the MEMS gyroscope makes a reciprocating vibration in the driving mode, if there is an external angular velocity input, the mass block will be affected by the Coriolis force, and thus a small lateral displacement will be generated perpendicular to the driving direction, that is, a displacement is generated in the sensitive mode and the sensitive mode response is output. The sensitive mode analog interface circuit inputs the sensitive mode response into the quadrature loop and the Coriolis loop in the sensitive mode respectively, and obtains the Coriolis output related to the Coriolis force and the quadrature output caused by noise and interference factors. In order to make the output of the MEMS gyroscope more stable and improve the accuracy of the speed measurement result, it is necessary to demodulate the quadrature output and the Coriolis output to generate a sensitive mode feedback signal and input it into the MEMS gyroscope again. When the preset number of cycles is reached or the output of the MEMS gyroscope tends to be stable, the motion angular velocity of the external moving object is calculated based on the Coriolis output obtained at the current moment.

[0003] Since the MEMS gyroscope is made of the thermosensitive material silicon, its performance is sensitive to temperature. When the temperature changes, the structural dimensions of the mass block in the MEMS gyroscope, the elastic modulus of the material, and the output signals of electronic components will all change. Furthermore, when there is no external angular velocity input to the MEMS gyroscope, its output signal will still deviate due to temperature influence, that is, zero bias temperature drift. This also means that when measuring the angular velocity, the output signal of the MEMS gyroscope contains deviation information caused by temperature influence, which is equivalent to introducing an error value related to the ambient temperature into the measurement result, thereby affecting the angular velocity measurement accuracy of the MEMS gyroscope.

[0004] Scholars at home and abroad have proposed several temperature compensation methods for the above-mentioned zero-offset temperature drift problem: 1. The University of Michigan and the Georgia Institute of Technology jointly proposed a low-power vacuum constant-temperature packaging technology for high-performance MEMS gyroscopes, that is, isolating the MEMS gyroscope through the packaging structure, and at the same time integrating a temperature sensor and a heating device to keep the temperature inside the packaging structure constant, thereby reducing the impact of temperature changes on the MEMS gyroscope. However, the method of controlling the temperature by optimizing the structure requires additional components and packaging equipment, with high costs. Moreover, it is also a major difficulty to design a packaging structure that can effectively isolate temperature and mechanical structure without affecting the heat dissipation performance. 2. The University of California, Irvine, proposed a passive temperature drift compensation method. Based on the theory that there is a linear relationship between the resonant frequency of the driving mode and the ambient temperature, the resonant frequency of the driving mode is used as a "thermometer" to achieve real-time temperature self-sensing. The corresponding relationship between the resonant frequency of the driving mode and the ambient temperature is established through calibration experiments, and the zero-offset output data of the MEMS gyroscope at different temperatures are obtained. During the detection process, the resonant frequency of the driving mode is measured in real time, and the ambient temperature at the current resonant frequency and the zero-offset output data at this ambient temperature are obtained. The output signal of the current MEMS gyroscope is subtracted from this zero-offset output data to achieve compensation for zero-offset temperature drift. This method requires measuring the zero-offset output of the MEMS gyroscope at a large number of temperature points and collecting the ambient temperatures corresponding to a large number of resonant frequencies of the driving mode, and then establishing the correlation among the three. The calibration experiment is cumbersome and time-consuming, increasing the time cost of detection and reducing the detection efficiency.

[0005] In summary, the existing zero-offset temperature drift suppression methods based on structural improvement have problems of high cost and difficult structural design, while the methods based on temperature modeling compensation have problems of complex calibration experiments, long time consumption, and affecting the detection efficiency. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problems of high cost and difficult structural design in the existing zero-offset temperature drift suppression methods based on structural improvement, and the problems of complex calibration experiments, long time consumption, and affecting the detection efficiency in the methods based on temperature modeling compensation.

[0007] To solve the above technical problems, the present invention provides a method for suppressing zero-offset temperature drift of a MEMS gyroscope, including:

[0008] S10: Inject a perturbation signal into the sensitive mode feedback signal at time t, and obtain the sensitive mode perturbation signal, Coriolis output, and quadrature output at time t based on the output of the MEMS gyroscope; wherein, the frequency of the perturbation signal is lower than the filter cut-off frequency and not equal to the resonant frequency of the MEMS gyroscope;

[0009] S20: Synthesize the phases of the orthogonal signal of the disturbance signal at time t and the phase control quantity at time t - 1 output by the PI controller to output the phase synthesis signal at time t; perform quadrature demodulation on the sensitive mode disturbance signal at time t using the phase synthesis signal at time t to obtain a quadrature demodulation signal containing the phase deviation between the disturbance signal and the sensitive mode disturbance signal at time t, and filter the quadrature demodulation signal to obtain the filtered signal at time t; among them, the phase control quantity output by the PI controller when t = 1 is 0;

[0010] S30: Input the filtered signal at time t into the PI controller to output the phase control quantity at time t, and use the phase control quantity at time t to perform phase compensation on the Coriolis output and quadrature output at time t to reduce the phase offset caused by temperature drift;

[0011] S40: Update t = t + 1, obtain the sensitive mode feedback signal at time t based on the compensated Coriolis output and quadrature output, return to execute step S10 until the filtered signal at time t is 0, input the filtered signal at time t into the PI controller, and output the target phase control quantity;

[0012] S50: Use the target phase control quantity to compensate the quadrature output and Coriolis output at time t to obtain the target quadrature output and target Coriolis output.

[0013] Preferably, compensating the quadrature output and Coriolis output using the phase control quantity / target phase control quantity includes:

[0014] Perform phase shift on the demodulation signal of the quadrature output based on the phase control quantity / target phase control quantity to obtain the first target demodulation signal; perform quadrature demodulation on the quadrature output using the first target demodulation signal to obtain the compensated quadrature output;

[0015] Perform phase shift on the demodulation signal of the Coriolis output based on the phase control quantity / target phase control quantity to obtain the second target demodulation signal; perform quadrature demodulation on the Coriolis output using the second target demodulation signal to obtain the compensated Coriolis output.

[0016] Preferably, the disturbance signal at time t is expressed as:

[0017] ,

[0018] where, represents the disturbance signal at time t; represents the frequency of the disturbance signal;

[0019] The orthogonal signal of the disturbance signal at time t is expressed as:

[0020] ,

[0021] Among them, represents the orthogonal signal of the disturbance signal at time t.

[0022] Preferably, the sensitive mode disturbance signal at time t is expressed as:

[0023] ,

[0024] Among them, represents the sensitive mode disturbance signal at time t; represents the conversion coefficient of vibration displacement and voltage; represents the sensitive mode gain of the MEMS gyroscope; represents the frequency of the disturbance signal; represents the phase shift of the output signal of the MEMS gyroscope affected by temperature at time t;

[0025] The phase synthesis signal at time t is expressed as:

[0026] ,

[0027] Among them, represents the phase synthesis signal at time t; represents the phase control amount output by the PI controller at

[0028] The filtered signal at time t is expressed as:

[0029] ,

[0030] Among them, represents the filtered signal at time t.

[0031] Preferably, the sensitive mode feedback signal at time t is expressed as:

[0032] ,

[0033] Among them, represents the sensitive mode feedback signal at time t; represents the quadrature output at represents the demodulated signal of the quadrature output at represents the first target demodulated signal after phase shift; represents the Coriolis output at time t; represents the demodulated signal of the Coriolis output at time t; represents the second target demodulated signal obtained based on the phase shift; represents the resonant frequency of the MEMS gyroscope; represents Phase control quantity at a moment.

[0034] Preferably, the target quadrature output is expressed as:

[0035] ,

[0036] wherein, represents the target quadrature output; represents the quadrature coupling force amplitude, , represents the Coriolis force coefficient, represents the drive mode gain; represents the conversion coefficient of the MEMS gyroscope excitation voltage to force;

[0037] The target Coriolis output is expressed as:

[0038] ,

[0039] wherein, represents the target Coriolis output; represents the effective mass of the axially symmetric gyro mass block, represents the angular gain coefficient, represents the input angular velocity, represents the resonant frequency of the MEMS gyroscope; represents the in-phase coupling force amplitude, , represents the damping coupling coefficient of the gyro y-axis to the x-axis.

[0040] Preferably, after obtaining the target quadrature output and the target Coriolis output, it further includes:

[0041] Based on the target Coriolis output and the zero-bias output of the calibrated MEMS gyroscope, obtain the target Coriolis output after removing the zero bias;

[0042] Based on the target Coriolis output after removing the zero bias, obtain the motion angular velocity of the object to be detected.

[0043] Preferably, the zero-bias output of the calibrated MEMS gyroscope is expressed as:

[0044] ,

[0045] wherein, represents the zero-bias output of the calibrated MEMS gyroscope; , represents the damping coupling coefficient of the gyro y-axis to the x-axis; represents the drive mode gain; represents the resonant frequency of the MEMS gyroscope; represents the conversion coefficient of the MEMS gyroscope excitation voltage to force.

[0046] The present invention also provides a MEMS gyro zero-bias temperature drift suppression system, including:

[0047] A signal generation module, whose first output end is connected to the sensitive mode input end of the MEMS gyroscope, and whose second output end is connected to the input end of the phase synthesis module; it is used to generate a disturbance signal and inject it into the sensitive mode feedback signal of the MEMS gyroscope, generate a quadrature signal of the disturbance signal and input it into the phase synthesis module; wherein, the frequency of the disturbance signal is lower than the filter cut-off frequency and not equal to the resonance frequency of the MEMS gyroscope;

[0048] A phase synthesis module, whose input end is connected to the second output end of the signal generation module and the output end of the PI controller, and whose output end is connected to the sensitive mode output end of the MEMS gyroscope; it is used to perform phase synthesis on the quadrature signal of the disturbance signal and the phase control quantity output by the PI controller, and output a phase synthesis signal to perform quadrature demodulation on the sensitive mode disturbance signal, so as to obtain a quadrature demodulation signal containing the phase deviation between the disturbance signal and the sensitive mode disturbance signal;

[0049] A signal filtering module, whose input end is connected to the sensitive mode output end of the MEMS gyroscope and the output end of the phase synthesis module, and whose output end is connected to the input end of the PI controller; it is used to filter the quadrature demodulation signal to obtain a filtered signal;

[0050] A PI controller, whose input end is connected to the output end of the signal filtering module, and whose output end is connected to the input end of the phase synthesis module and the microcontroller of the MEMS gyroscope; it is used to output a phase control quantity / target phase control quantity based on the filtered signal, so that the microcontroller can use the phase control quantity / target phase control quantity to compensate the quadrature output and the Coriolis output.

[0051] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above-mentioned MEMS gyro zero-bias temperature drift suppression method are implemented.

[0052] The MEMS gyro zero-bias temperature drift suppression method provided by this application has the following beneficial effects:

[0053] In this application, a perturbation signal with a frequency different from the resonance frequency of the MEMS gyroscope is introduced into the sensitive mode feedback signal to perturb the MEMS gyroscope. By extracting the phase error of the output signal caused by temperature influence on the MEMS gyroscope through the externally applied perturbation signal, the phase error is compensated to offset the influence of temperature on the output signal of the MEMS gyroscope. Specifically, a perturbation signal is injected into the sensitive mode feedback signal. When this signal passes through the MEMS gyroscope, the phase of the perturbation signal will also have a phase shift due to temperature influence, that is, the sensitive mode perturbation signal output by the MEMS gyroscope will contain the phase shift term of the output signal caused by temperature influence on the MEMS gyroscope. At this time, the quadrature signal of the perturbation signal is phase - synthesized with the phase control quantity output by the PI controller at the previous moment to obtain the phase - synthesized signal at the current moment. Since this phase - synthesized signal contains the phase compensation quantity at the previous moment and the phase information of the perturbation signal, the phase error information between the sensitive mode perturbation signal and the perturbation signal at the current moment is extracted by performing quadrature demodulation on the sensitive mode perturbation signal at the current moment using this phase - synthesized signal. After filtering the signal after quadrature demodulation to obtain the filtered signal at the current moment, it is input into the PI controller. The PI controller outputs the phase control quantity at the next moment based on the phase error information between the sensitive mode perturbation signal and the preset perturbation signal at the current moment, which is the phase adjustment quantity required to correct the current phase error. The Coriolis output and quadrature output at the current moment are compensated using the phase control quantity at the next moment to obtain the sensitive mode feedback signal at the next moment, and a new round of perturbation and phase error compensation is performed. As the number of iterations increases, the PI controller continuously adjusts the phase error between the sensitive mode perturbation signal and the perturbation signal, and the filtered signal becomes smaller and smaller. When the filtered signal is 0, it indicates that there is no longer a phase error between the sensitive mode perturbation signal and the perturbation signal. At this time, the phase control quantity output by the PI controller is the target phase control quantity required to completely offset the temperature influence. The Coriolis output and quadrature output compensated using this target phase control quantity are the target Coriolis output and target quadrature output that no longer contain temperature error components. This application uses the PI controller to perform real - time tracking and correction of the phase error, which can automatically follow the change of the phase error even when the temperature changes and generate the corresponding target phase control quantity, effectively suppressing the influence of the zero - bias temperature drift of the MEMS gyroscope on the measurement result, improving the measurement accuracy and stability of the MEMS gyroscope. It neither needs to introduce high - cost packaging equipment, design complex packaging structures, nor needs to perform a large number of calibration experiments, improving the detection efficiency of the MEMS gyroscope. Description of the Drawings

[0054] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in combination with the drawings, where:

[0055] Figure 1 Schematic diagram of the MEMS gyroscope structure provided by this application;

[0056] Figure 2 Schematic diagram of the sensitive mode phase model structure of the MEMS gyroscope provided by this application;

[0057] Figure 3 Flowchart of the method for suppressing the zero-bias temperature drift of the MEMS gyroscope provided by this application;

[0058] Figure 4 Schematic diagram of the principle for suppressing the zero-bias temperature drift of the MEMS gyroscope provided by this application;

[0059] Figure 5 Schematic diagram of the phase correction loop simulation model provided by the embodiment of this application;

[0060] Figure 6 Schematic diagram of the simulation result of the phase correction loop provided by the embodiment of this application; wherein, Figure 6 in (a) is the schematic diagram of the input signal phase, Figure 6 in (b) is the schematic diagram of the compensation phase generated by the phase loop;

[0061] Figure 7 Schematic diagram of the MEMS gyroscope simulation model provided by the embodiment of this application;

[0062] Figure 8 Schematic diagram of the simulation results of the MEMS gyroscope before and after phase correction using the method provided by this application; wherein, Figure 8 in (a) is the schematic diagram of the Coriolis output of the MEMS gyroscope before and after phase correction, Figure 8 in (b) is the schematic diagram of the quadrature output of the MEMS gyroscope before and after phase correction. Detailed implementation manners

[0063] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the specific embodiments given are not intended to limit the present invention.

[0064] Please refer to Figure 1 as shown in Figure 1Schematic diagram of the MEMS gyroscope structure provided by this application, which mainly includes a driving mode, a sensitive mode, and an analog interface circuit. The analog interface circuit includes a gyro mass block and an interface circuit. The driving mode part adopts an AGC-PLL system. In order to reduce interference, a high-frequency modulation technology is used: a 1 MHz carrier is applied to the gyro mass block, and the vibration displacement signal is modulated to a high frequency, and then the original displacement signal is extracted through demodulation by the interface circuit. The sensitive mode adopts a force balance closed-loop control system, and in-phase and quadrature demodulation are performed on the sensitive output to obtain the amplitudes of the Coriolis response and the quadrature response. A PI controller is used to generate two paths of feedback forces to cancel the Coriolis force, the in-phase coupling force, and the quadrature force, so as to maintain the relative rest of the sensitive mode. The PI output of the in-phase channel is the angular velocity output.

[0065] In the actual working process of the gyroscope, the analog interface circuit will inevitably generate phase shifts, which mainly come from the interface circuit, the ADC, and the DAC. In order to analyze the influence brought by the phase shift in this application, Figure 1 key signal points are marked: the phase shifts generated by the ADC and the DAC are respectively denoted as and , the total phase shift generated by the analog interface circuit is denoted as , the total phase shift is denoted as , that is , then the phase relationship of each point signal is shown in Table 1:

[0066] Table 1

[0067]

[0068] As Figure 2 shown is the schematic diagram of the sensitive mode phase model structure of the MEMS gyroscope provided by this application. Considering the circuit phase shift, in the non-ideal case, the expressions of the Coriolis force , the in-phase coupling force and the quadrature coupling force are respectively:

[0069] ,

[0070] where represents the driving mode gain; represents the driving mode phase shift; represents the resonant frequency of the MEMS gyroscope.

[0071] The input of the sensitive mode is the in-phase resultant force and the quadrature force , where includes the in-phase coupling force and the Coriolis force caused by the angular rate, then the input of the sensitive mode can be expressed as:

[0072] ,

[0073] wherein, , represents the resonant frequency of the MEMS gyroscope; , , represents the drive mode gain, represents the Coriolis force coefficient.

[0074] The displacement caused by the resultant force of the sensitive mode input can be obtained (point E) is:

[0075] ,

[0076] wherein, represents the sensitive mode gain; represents the sensitive mode phase shift, when the modes are matched , is maximum and . Under the dual-channel force balance, the sensitive mode feedback signal (point G) generated by the measurement and control circuit in the FPGA can be expressed as:

[0077] ,

[0078] wherein, and are the amplitudes of the in-phase and quadrature feedback signals respectively, and are also the outputs of the Coriolis and quadrature channels. The analog feedback signal (point H) is:

[0079] ,

[0080] According to the force balance principle, in the ideal state, the sensitive mode is relatively stationary. At this time, the resultant force of the feedback force, the in-phase resultant force and the orthogonal force is 0, that is:

[0081] ,

[0082] wherein, represents the conversion coefficient of the excitation voltage and force of the MEMS gyroscope. Solving, the expressions of the Coriolis output and the quadrature output can be obtained as:

[0083] ,

[0084] When there is no angular velocity input, , then the zero-bias output of the gyroscope under the dual-channel force balance can be expressed as:

[0085] ,

[0086] Based on the above derivation process, it can be seen that the zero offset is related to the phase shift of the gyroscope drive mode. Since in the drive mode, in order to maintain resonance, the PLL locks the phase difference between the input signal (point D) and the output signal (point A) at -90°. As can be seen from Table 1 , the zero-offset output of the gyroscope can be written as:

[0087] ,

[0088] It can be seen that the zero-offset output is affected by the in-phase coupling force amplitude , the quadrature coupling force amplitude and the circuit phase shift . For a high-Q MEMS axisymmetric gyroscope with vacuum packaging, is several orders of magnitude smaller than , and the drift of the in-phase coupling force is also much smaller than the drift of the quadrature coupling force. Therefore, the in-phase error is equivalent to introducing a fixed bias to the zero offset. causes a phase error between the force input to the sensitive mode and the feedback force, thereby introducing the quadrature error into the Coriolis channel and forming a larger fixed bias in the zero offset. As the temperature changes, and will both drift, ultimately resulting in a large zero-offset temperature drift.

[0089] Based on the above analysis, it is found in this application that the phase error has an important impact on the zero offset. Real-time compensation of the phase error can suppress the zero-offset temperature drift and improve the zero-offset stability of the gyroscope in a variable-temperature environment.

[0090] Based on the above conclusion, this application provides a method for suppressing the zero-offset temperature drift of a MEMS gyroscope. As Figure 3 shown, the method specifically includes:

[0091] S10: Inject a perturbation signal into the sensitive-mode feedback signal at time t, and obtain the sensitive-mode perturbation signal, the Coriolis output, and the quadrature output at time t based on the output of the MEMS gyroscope; wherein, the frequency of the perturbation signal is lower than the filter cut-off frequency and not equal to the resonance frequency of the MEMS gyroscope.

[0092] Specifically, the filter cut-off frequency refers to the cut-off frequency of the filter used for filtering the signal.

[0093] S20: Synthesize the phase of the orthogonal signal of the disturbance signal at time t and the phase control quantity at time t-1 output by the PI controller to output the phase synthesis signal at time t; use the phase synthesis signal at time t to perform quadrature demodulation on the sensitive mode disturbance signal at time t to obtain a quadrature demodulation signal containing the phase deviation between the disturbance signal and the sensitive mode disturbance signal at time t, and filter the quadrature demodulation signal to obtain the filtered signal at time t; wherein, the phase control quantity output by the PI controller when t = 1 is 0.

[0094] S30: Input the filtered signal at time t into the PI controller to output the phase control quantity at time t, and use the phase control quantity at time t to perform phase compensation on the Coriolis output and quadrature output at time t to reduce the phase offset caused by temperature drift.

[0095] S40: Update t = t + 1, obtain the sensitive mode feedback signal at time t based on the compensated Coriolis output and quadrature output, return to execute step S10 until the filtered signal at time t is 0, input the filtered signal at time t into the PI controller, and output the target phase control quantity.

[0096] S50: Use the target phase control quantity to compensate the quadrature output and Coriolis output at time t to obtain the target quadrature output and target Coriolis output.

[0097] Specifically, in some embodiments of the present application, the disturbance signal at time t is expressed as:

[0098] ,

[0099] wherein, represents the disturbance signal at time t; represents the frequency of the disturbance signal;

[0100] The orthogonal signal of the disturbance signal at time t is expressed as:

[0101] ,

[0102] wherein, represents the orthogonal signal of the disturbance signal at time t.

[0103] The sensitive mode disturbance signal at time t is expressed as:

[0104] ,

[0105] wherein, represents the sensitive mode disturbance signal at time t; represents the conversion coefficient of vibration displacement and voltage; represents the sensitive mode gain of the MEMS gyroscope; represents the frequency of the disturbance signal; Denote the output signal phase shift of the MEMS gyroscope affected by temperature at time t;

[0106] The phase synthesis signal at time t is expressed as:

[0107] ,

[0108] where, Denote the phase synthesis signal at time t; Denote the phase control quantity at time

[0109] The filtered signal at time t is expressed as:

[0110] ,

[0111] where, Denote the filtered signal at time t.

[0112] Furthermore, compensating the quadrature output and the Coriolis output using the phase control quantity / target phase control quantity includes:

[0113] Performing phase shift on the demodulation signal of the quadrature output based on the phase control quantity / target phase control quantity to obtain a first target demodulation signal; using the first target demodulation signal to perform quadrature demodulation on the quadrature output to obtain a compensated quadrature output;

[0114] Performing phase shift on the demodulation signal of the Coriolis output based on the phase control quantity / target phase control quantity to obtain a second target demodulation signal; using the second target demodulation signal to perform quadrature demodulation on the Coriolis output to obtain a compensated Coriolis output.

[0115] Furthermore, the sensitive mode feedback signal at time t is expressed as:

[0116] ,

[0117] where, Denote the sensitive mode feedback signal at time t; Denote the quadrature output at time Denote the demodulation signal of the quadrature output at time Denote the first target demodulation signal after phase shift; Denote the Coriolis output at time t; Denote the demodulation signal of the Coriolis output at time t; Denote the second target demodulation signal obtained based on phase shift; Denote the resonant frequency of the MEMS gyroscope; Denote Phase control quantity at a moment.

[0118] Furthermore, the target quadrature output is expressed as:

[0119] ,

[0120] wherein, represents the target quadrature output; represents the quadrature coupling force amplitude, , represents the Coriolis force coefficient, represents the drive mode gain; represents the conversion coefficient of the excitation voltage and force of the MEMS gyroscope;

[0121] The target Coriolis output is expressed as:

[0122] ,

[0123] wherein, represents the target Coriolis output; represents the effective mass of the axially symmetric gyro mass block, represents the angular gain coefficient, represents the input angular velocity, represents the resonant frequency of the MEMS gyroscope; represents the in-phase coupling force amplitude, , represents the damping coupling coefficient of the gyro y-axis to the x-axis.

[0124] Furthermore, in some embodiments of the present application, after obtaining the target quadrature output and the target Coriolis output, it further includes:

[0125] Based on the target Coriolis output and the zero-bias output of the calibrated MEMS gyroscope, obtain the target Coriolis output after removing the zero bias;

[0126] Specifically, the zero-bias output of the calibrated MEMS gyroscope is expressed as:

[0127] ,

[0128] wherein, represents the zero-bias output of the calibrated MEMS gyroscope; , represents the damping coupling coefficient of the gyro y-axis to the x-axis; represents the drive mode gain; represents the resonant frequency of the MEMS gyroscope; represents the conversion coefficient of the excitation voltage and force of the MEMS gyroscope.

[0129] Obtain the motion angular velocity of the moving object to be detected based on the target Coriolis output after removing the zero offset.

[0130] As Figure 4 shown in the schematic diagram of the MEMS gyro zero-offset temperature drift suppression principle provided by this application, the phase correction loop part in the figure can implement the above-mentioned MEMS gyro zero-offset temperature drift suppression method, and its specific principle is as follows:

[0131] Add the perturbation signal to the position of point G, and the disturbing force generated at the input end of the gyroscope sensitive mode can be expressed as:

[0132] ,

[0133] The sensitive mode output displacement (point E) caused by the disturbing force can be obtained from the sensitive mode transfer function as:

[0134] ,

[0135] ,

[0136] ,

[0137] Design the frequency of the perturbation signal to be far from the resonance frequency of the gyroscope, and it can be obtained that:

[0138] ,

[0139] After passing through the interface circuit (point F), the perturbation signal can be expressed as:

[0140] ,

[0141] where represents the conversion coefficient between vibration displacement and voltage.

[0142] Multiply by the demodulation signal of the in-phase channel, and sum-frequency components and difference-frequency components are simultaneously generated in the spectrum, that is:

[0143] ,

[0144] Since the frequency of the perturbation signal is far from the resonance frequency of the gyroscope, the perturbation signal will be filtered out by the low-pass filter of the in-phase channel. Similarly, the perturbation signal cannot pass through the low-pass filter of the quadrature channel. Therefore, the perturbation signal will not affect the in-phase and quadrature channels.

[0145] It can be seen that the signal contains the phase error , denote the output of the PI controller of the phase correction loop at time t-1 as , and use the signal output by the phase synthesizer to perform quadrature demodulation. After passing through a low-pass filter, we get:

[0146] ,

[0147] When the loop starts, is 0, is relatively large. After adjustment by the PI controller, constantly increases, rapidly decreases until , at this time , the phase correction loop reaches stability. The output of the PI controller at stability is the target phase control amount. It should be noted that when the temperature changes, drifts accordingly, and the loop can automatically calculate the current magnitude and output the target phase control amount .

[0148] Compensate the sensitive mode feedback signal through the phase synthesizer (G point), and the resulting target sensitive mode feedback signal is expressed as:

[0149] ,

[0150] The analog feedback signal (H point) after passing through the DAC is:

[0151] ,

[0152] The feedback force cancels out the in-phase resultant force and the quadrature force, that is:

[0153] ,

[0154] Since , the in-phase resultant force and the quadrature force can be written as:

[0155] ,

[0156] Through the above formulas, the expressions of the Coriolis output and the quadrature output after phase compensation can be obtained as:

[0157] ,

[0158] Since when the loop is stable, the target Coriolis output and the target quadrature output are:

[0159] ,

[0160] When there is no angular velocity input, , the zero-bias output can be expressed as:

[0161] ,

[0162] It can be seen that after phase compensation, the zero-bias output is no longer affected by the circuit phase shift and the amplitude of the quadrature coupling force . The zero-bias shows as a very small fixed bias, which can be eliminated through simple calibration.

[0163] From the above principle derivation process and results, it can be seen that the phase error can be extracted through the phase correction loop, and an equal compensation phase can be automatically generated, thus avoiding the influence of the quadrature error. As the temperature changes, the loop can automatically follow the change of the phase error. Therefore, adding the phase correction loop can suppress the temperature drift of the zero-bias in real time and improve the temperature robustness of the MEMS gyroscope system.

[0164] Furthermore, based on the above method for suppressing the zero-bias temperature drift of the MEMS gyro, the embodiment of the present application also provides a system for suppressing the zero-bias temperature drift of the MEMS gyro, as Figure 4 shown in the phase loop correction part in, the system specifically includes:

[0165] A signal generation module, whose first output terminal is connected to the sensitive mode input terminal of the MEMS gyroscope, and whose second output terminal is connected to the input terminal of the phase synthesis module; it is used to generate a perturbation signal and inject it into the sensitive mode feedback signal of the MEMS gyroscope, and generate a quadrature signal of the perturbation signal and input it into the phase synthesis module; wherein, the frequency of the perturbation signal is lower than the filter cut-off frequency and not equal to the resonance frequency of the MEMS gyroscope;

[0166] A phase synthesis module, whose input terminal is connected to the second output terminal of the signal generation module and the output terminal of the PI controller, and whose output terminal is connected to the sensitive mode output terminal of the MEMS gyroscope; it is used to perform phase synthesis on the quadrature signal of the perturbation signal and the phase control quantity output by the PI controller, and output a phase synthesis signal to perform quadrature demodulation on the sensitive mode perturbation signal, so as to obtain a quadrature demodulation signal containing the phase deviation between the perturbation signal and the sensitive mode perturbation signal;

[0167] A signal filtering module, whose input terminal is connected to the sensitive mode output terminal of the MEMS gyroscope and the output terminal of the phase synthesis module, and whose output terminal is connected to the input terminal of the PI controller; it is used to filter the quadrature demodulation signal to obtain a filtered signal;

[0168] A PI controller, whose input terminal is connected to the output terminal of the signal filtering module, and whose output terminal is connected to the input terminal of the phase synthesis module and the microcontroller of the MEMS gyroscope; it is used to output a phase control quantity / target phase control quantity based on the filtered signal, so that the microcontroller can use the phase control quantity / target phase control quantity to compensate for the quadrature output and the Coriolis output.

[0169] Specifically, in some embodiments of the present application, the signal generation module may adopt a numerically controlled oscillator, the phase synthesis module may adopt a phase synthesizer, and the signal filtering module may adopt a low-pass filter.

[0170] The embodiment of the present application also provides a MEMS gyroscope, which includes the above-mentioned MEMS gyro zero-bias temperature drift suppression system.

[0171] The effectiveness of the MEMS gyro zero-bias temperature drift suppression method provided by the above embodiment is verified through a specific example below, as Figure 5 shown is the Simulink simulation model of the phase correction loop part constructed based on the above MEMS gyro zero-bias temperature drift suppression system in the embodiment of the present application. This loop specifically includes a multiplier, a low-pass filter, a PI controller, a phase synthesizer, and a numerically controlled oscillator.

[0172] In this model, sine signals with frequencies of 2 kHz and phases of , and are input successively, each lasting for 2 s. The demodulation signal is generated by the numerically controlled oscillator and the phase synthesizer. The parameters , of the PI are set to 0.6 and 80 respectively. The simulation results are as Figure 6 shown, where (a) in Figure 6 is the schematic diagram of the input signal phase, and (b) in Figure 6 is the schematic diagram of the compensation phase generated by the phase loop.

[0173] It can be seen from Figure 6 that the time required for the loop to start up and stabilize is less than 1 s. After stabilization, the measured compensation phases output by the loop are , and respectively, which are consistent with the phases of the input signals. When the phase of the input signal is changed within the range of , the simulation is repeated multiple times, and the phases of the input signals can be extracted.

[0174] Table 2 shows the simulation system parameters of a MEMS axisymmetric gyro provided in this embodiment:

[0175] Table 2

[0176]

[0177] In this embodiment, a phase correction loop is added to compensate for the phase error of the MEMS axisymmetric gyroscope. As Figure 7 shown in the schematic diagram of the MEMS gyroscope simulation model constructed in this embodiment, it specifically includes a gyro mass block, an interface circuit, a sensitive mode, a driving mode, and the MEMS gyro zero-bias temperature drift suppression system (i.e., the phase correction loop) provided in the above embodiment.

[0178] Simulate the phase compensation effect: Add phase shift to the interface circuit module of the simulation model, and the input angular velocities are 0° / s, 10° / s, 20° / s, and 30° / s respectively, each lasting for 5 s. The simulation results of the Coriolis output and the quadrature output before and after the model improvement are compared as Figure 8 shown. Among them, Figure 8 in (a) is the schematic diagram of the Coriolis output of the MEMS gyroscope before and after phase correction, Figure 8 in (b) is the schematic diagram of the quadrature output of the MEMS gyroscope before and after phase correction.

[0179] As can be seen from Figure 8 , when the angular velocity input is 0 before improvement, due to the phase error, the quadrature error is introduced into the in-phase channel, and there is a fixed bias in the zero-bias output. When there is an angular velocity signal input, both the Coriolis and quadrature outputs change with the angular velocity. After improvement by the phase correction loop, when the angular velocity input is 0, the zero-bias output is corrected to 0. When there is an angular velocity signal input, the Coriolis output changes with the angular velocity, while the quadrature output is a fixed bias after loop adjustment. The simulation results show that after adding the phase correction loop, the phase error of the feedback signal is compensated, and the suppression of zero-bias temperature drift is achieved.

[0180] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0181] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0182] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0183] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0184] Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to exhaustively list all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for suppressing the zero bias temperature drift of a MEMS gyroscope, characterized in that, Including: S10: Inject a perturbation signal into the sensitive mode feedback signal at time t, and obtain the sensitive mode perturbation signal, Coriolis output, and quadrature output at time t based on the output of the MEMS gyroscope; wherein, the frequency of the perturbation signal is lower than the filter cut-off frequency and not equal to the resonant frequency of the MEMS gyroscope. S20: Perform phase synthesis on the quadrature signal of the perturbation signal at time t and the phase control quantity at time t-1 output by the PI controller to output the phase synthesis signal at time t; use the phase synthesis signal at time t to perform quadrature demodulation on the sensitive mode perturbation signal at time t to obtain a quadrature demodulation signal containing the phase deviation between the perturbation signal and the sensitive mode perturbation signal at time t, and filter the quadrature demodulation signal to obtain the filtered signal at time t; wherein, the phase control quantity output by the PI controller when t = 1 is 0. S30: Input the filtered signal at time t into the PI controller to output the phase control quantity at time t, and use the phase control quantity at time t to perform phase compensation on the Coriolis output and quadrature output at time t to reduce the phase offset caused by temperature drift. S40: Update t = t + 1, obtain the sensitive mode feedback signal at time t based on the compensated Coriolis output and quadrature output, return to execute step S10 until the filtered signal at time t is 0, input the filtered signal at time t into the PI controller, and output the target phase control quantity. S50: Use the target phase control quantity to compensate the quadrature output and Coriolis output at time t to obtain the target quadrature output and target Coriolis output.

2. The method for suppressing the zero bias temperature drift of the MEMS gyroscope according to claim 1, wherein Compensating the quadrature output and Coriolis output using the phase control quantity / target phase control quantity includes: Performing a phase shift on the demodulation signal of the quadrature output based on the phase control quantity / target phase control quantity to obtain a first target demodulation signal; using the first target demodulation signal to perform quadrature demodulation on the quadrature output to obtain the compensated quadrature output. Performing a phase shift on the demodulation signal of the Coriolis output based on the phase control quantity / target phase control quantity to obtain a second target demodulation signal; using the second target demodulation signal to perform quadrature demodulation on the Coriolis output to obtain the compensated Coriolis output.

3. The method for suppressing the zero-bias temperature drift of the MEMS gyroscope according to claim 1, characterized in that The perturbation signal at time t is expressed as: ， Among them, represents the disturbance signal at time t; represents the frequency of the disturbance signal; The quadrature signal of the perturbation signal at time t is expressed as: ， Among them, represents the orthogonal signal of the disturbance signal at time t.

4. The MEMS gyro zero-bias temperature drift suppression method according to claim 1, characterized in that The sensitive mode perturbation signal at time t is expressed as: ， Among them, represents the sensitive modal disturbance signal at time t; represents the conversion coefficient between vibration displacement and voltage; represents the sensitive modal gain of the MEMS gyroscope; represents the frequency of the disturbance signal; represents the output signal phase shift of the MEMS gyroscope affected by temperature at time t; The phase synthesis signal at time t is expressed as: ， Among them, represents the phase synthesis signal at time t; represents the phase control quantity at time The filtered signal at time t is expressed as: ， Among them, represents the filtered signal at time t.

5. The method for suppressing the zero-bias temperature drift of the MEMS gyroscope according to claim 2, wherein The sensitive mode feedback signal at time t is expressed as: ， Among them, represents the sensitive modal feedback signal at time t; represents the quadrature output at time represents the demodulated signal of the quadrature output at time represents the first target demodulated signal after phase offset; represents the Coriolis output at time t; represents the demodulated signal of the Coriolis output at time t; represents the second target demodulated signal obtained based on the phase offset; represents the resonant frequency of the MEMS gyroscope; represents the phase control amount at time 6. The MEMS gyro zero-bias temperature drift suppression method according to claim 1, characterized in that, The target quadrature output is expressed as: ， Among them, represents the target orthogonal output; represents the orthogonal coupling force amplitude, , represents the Coriolis force coefficient, represents the drive mode gain; represents the conversion coefficient of the excitation voltage and force of the MEMS gyroscope; The target Coriolis output is expressed as: ， Among them, represents the target Coriolis output; , represents the effective mass of the axially symmetric gyro mass block, represents the angular gain coefficient, represents the input angular velocity, represents the resonant frequency of the MEMS gyroscope; represents the in-phase coupling force amplitude, , represents the damping coupling coefficient of the gyro y-axis to the x-axis.

7. The method for suppressing the zero-offset temperature drift of the MEMS gyroscope according to claim 1, characterized in that, After obtaining the target quadrature output and target Coriolis output, it further includes: Based on the target Coriolis output and the zero bias output of the calibrated MEMS gyroscope, obtain the target Coriolis output after removing the zero bias. Based on the target Coriolis output after removing the zero bias, obtain the motion angular velocity of the object to be detected.

8. The MEMS gyro zero-bias temperature drift suppression method according to claim 7, characterized in that, The zero bias output of the calibrated MEMS gyroscope is expressed as: ， Among them, represents the zero-bias output of the calibrated MEMS gyroscope; , represents the damping coupling coefficient of the gyro y-axis to the x-axis; represents the drive mode gain; represents the resonance frequency of the MEMS gyroscope; represents the conversion coefficient of the excitation voltage and force of the MEMS gyroscope.

9. A MEMS gyro zero-bias temperature drift suppression system, characterized in that, Including: A signal generation module, whose first output terminal is connected to the sensitive mode input terminal of the MEMS gyroscope, and whose second output terminal is connected to the input terminal of the phase synthesis module. It is used to generate a perturbation signal and inject it into the sensitive mode feedback signal of the MEMS gyroscope, generate the quadrature signal of the perturbation signal and input it into the phase synthesis module; wherein, the frequency of the perturbation signal is lower than the filter cut-off frequency and not equal to the resonant frequency of the MEMS gyroscope. The phase synthesis module, whose input end is connected to the second output end of the signal generation module and the output end of the PI controller, and whose output end is connected to the sensitive mode output end of the MEMS gyroscope; it is used to perform phase synthesis on the quadrature signal of the perturbation signal and the phase control quantity output by the PI controller, and output a phase synthesis signal to perform quadrature demodulation on the sensitive mode perturbation signal, so as to obtain a quadrature demodulation signal containing the phase deviation between the perturbation signal and the sensitive mode perturbation signal. The signal filtering module, whose input end is connected to the sensitive mode output end of the MEMS gyroscope and the output end of the phase synthesis module, and whose output end is connected to the input end of the PI controller; it is used to filter the quadrature demodulation signal to obtain a filtered signal. The PI controller, whose input end is connected to the output end of the signal filtering module, and whose output end is connected to the input end of the phase synthesis module and the microcontroller of the MEMS gyroscope; it is used to output a phase control quantity / target phase control quantity based on the filtered signal, so that the microcontroller can use the phase control quantity / target phase control quantity to compensate the quadrature output and the Coriolis output.

10. A MEMS gyroscope, characterized in that, The MEMS gyroscope includes the MEMS gyro zero-bias temperature drift suppression system as described in claim 9.

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