MEMS Gyroscope and Its Error Suppression Method, Angular Velocity Measurement Method

Abstract

The present invention discloses a MEMS gyroscope based on dithering and force feedback, an error suppression method thereof, and an angular velocity measurement method. The MEMS gyroscope based on dithering and force feedback of the present invention includes a sensitive structure, a sensitive structure driving module, a sensitive structure detection module, a dithering structure, a dithering driving module, a dithering detection module, an angular velocity calculation module, and a force feedback module. The present invention adopts periodic dithering modulation of the sensitive axis of the gyroscope and adds force feedback detection, which ensures the sensitivity of the gyroscope while completely eliminating zero-bias calibration and zeroing, and suppresses the angular random walk caused by white noise, realizes non-divergence of angular velocity integration, and expands the application of MEMS gyroscopes in the field of pure inertial navigation with long endurance and long range.

Description

Technical Field

[0001] The present invention belongs to the technical field of gyroscopes, and relates to error suppression of MEMS gyroscopes, and in particular to a MEMS gyroscope based on jitter and force feedback, an error suppression method thereof, and an angular velocity measurement method. Background Art

[0002] MEMS gyroscopes have the characteristics of small size, light weight, low power consumption, easy integration, strong overload capacity and mass production. Currently, the performance of conventional MEMS gyroscopes can meet most application requirements.

[0003] Gyroscope bias refers to the angular velocity output produced when there is no rotational input to the gyroscope's sensitive axis. During manufacturing, each individual gyroscope is calibrated to have a relatively small bias. However, the bias is not fixed over time and will drift with factors such as temperature changes and aging of the materials used in the sensor. Gyroscopes that are stored for a long time need to be re-zeroed regularly. This periodic calibration and compensation consumes manpower and material resources and increases the time cost of use.

[0004] High sensitivity can greatly improve the zero-bias performance of the gyroscope. However, the existing method of improving the sensitivity of the MEMS gyroscope results in a very low bandwidth of the gyroscope, which is not suitable for engineering applications.

[0005] In addition, the introduction of system white noise is unavoidable, and the impact of white noise on the gyroscope is manifested as angle random walk. Angle random walk is a non-stationary random process with a mean of 0, a variance that increases with time, and a correlation that increases with time, affecting the alignment accuracy and alignment time of the inertial navigation system.

[0006] Therefore, zero bias and white noise are prominent problems that restrict the application of MEMS gyroscopes and need to be solved urgently. Summary of the invention

[0007] The purpose of the present invention is to improve the measurement accuracy of the MEMS gyroscope, ensure the sensitivity of the MEMS gyroscope while completely eliminating the need for periodic calibration and zeroing of the zero bias, and suppress the angle random walk caused by white noise to achieve non-divergence of angular velocity integral.

[0008] To achieve the above-mentioned purpose, the present invention provides a MEMS gyroscope based on jitter and force feedback, comprising: a sensitive structure, a sensitive structure driving module, a sensitive structure detection module, a jitter structure, a jitter driving module, a jitter detection module, an angular velocity calculation module, and a force feedback module; wherein,

[0009] The sensitive structure includes a driving end and a detection end, and the sensitive structure driving module is used to generate a first driving voltage to make the sensitive structure driving end vibrate;

[0010] The dithering structure is connected to the sensitive structure. The dithering driving module is used to generate a second driving voltage to drive the dithering of the dithering structure, and the dithering of the dithering structure drives the dithering of the sensitive axis of the sensitive structure;

[0011] The dithering structure detection module is used to detect the dithering modulation signal generated by the dithering of the dithering structure, and output the dithering modulation signal to the angular velocity calculation module and the force feedback module;

[0012] The sensitive structure detection module is used to detect the velocity and displacement of the driving end vibration of the sensitive structure, output the driving end displacement signal to the angular velocity calculation module, output the driving end velocity signal to the force feedback module, detect the electrical signal of the detection end of the sensitive structure and output the detection signal to the angular velocity calculation module;

[0013] The angular velocity calculation module demodulates, filters and performs PI control on the detection signal according to the dithering modulation signal and the driving end displacement signal to obtain the signal after PI control. One path of the signal after PI control is used as the angular velocity signal, and the other path is output to the force feedback module;

[0014] The force feedback module is used to obtain the force feedback signal according to the driving end velocity signal, the dithering modulation signal and the signal after PI control, and apply the force feedback signal to the detection end of the sensitive structure to cancel the Coriolis force generated by the angular velocity input when there is an angular velocity input.

[0015] Further, the angular velocity calculation module includes a first multiplier, a second multiplier, a low-pass filter, a frequency doubling notch filter, and a PI controller;

[0016] The first multiplier is used to multiply the detection signal by the dithering modulation signal to obtain a first demodulation signal;

[0017] The second multiplier is used to multiply the first demodulation signal by the driving end displacement signal to obtain a second demodulation signal;

[0018] The low-pass filter and the frequency doubling notch filter are used to filter the second demodulation signal to eliminate zero bias and power frequency interference;

[0019] The PI controller performs PI control on the signal eliminating zero bias and power frequency interference to obtain the signal after PI control.

[0020] Further, the force feedback module includes a third multiplier and a fourth multiplier;

[0021] The third multiplier is used to multiply the signal after PI control by the driving end velocity signal;

[0022] The fourth multiplier is used to multiply the output of the third multiplier by the dithering modulation signal.

[0023] Further, the step of using the signal after PI control as the angular velocity signal is to obtain the angular velocity signal by performing a proportional transformation on the signal after PI control.

[0024] Further, the dithering frequency of the dithering structure is equal to the difference between the detection frequency of the detection end of the sensitive structure and the driving frequency of the driving end.

[0025] The present invention also provides a method for suppressing errors of a MEMS gyroscope based on dithering and force feedback, including the steps of:

[0026] The step of starting the MEMS gyroscope; the MEMS gyroscope has a dithering structure and a sensitive structure, the sensitive structure includes a driving end and a detection end, after the MEMS gyroscope is started, the driving end of the sensitive structure is driven by a first driving voltage to make the sensitive structure vibrate around its sensitive axis, the angular velocity to be measured is modulated by the vibration of the driving end, and, the dithering structure is driven by a second driving voltage to dither and at the same time drive the sensitive axis of the sensitive structure to dither;

[0027] The step of obtaining the dithering modulation signal generated by the dithering of the dithering structure;

[0028] The step of obtaining the velocity signal and displacement signal of the vibration of the driving end of the sensitive structure;

[0029] The step of obtaining the electrical signal of the detection end of the sensitive structure of the MEMS gyroscope;

[0030] The step of multiplying the electrical signal of the detection end by the dithering modulation signal and then multiplying the result by the displacement signal of the driving end to obtain a demodulation signal;

[0031] The step of performing low-pass filtering and frequency doubling notch filtering on the demodulation signal to eliminate zero bias and power frequency interference;

[0032] The step of performing PI control on the signal after eliminating zero bias and power frequency interference to obtain a signal after PI control;

[0033] The step of multiplying the signal after PI control by the velocity signal of the driving end and then multiplying the result by the dithering modulation signal to obtain a force feedback signal;

[0034] The step of applying the force feedback signal to the detection end of the sensitive structure, the action of the force feedback signal on the sensitive structure cancels the Coriolis force generated by the angular velocity input when there is an angular velocity input.

[0035] Further, the method for suppressing errors of the MEMS gyroscope further includes: the dithering frequency of the dithering structure is equal to the difference between the detection frequency of the detection end of the sensitive structure and the driving frequency of the driving end.

[0036] The present invention also provides an angular velocity measurement method for a MEMS gyroscope based on dithering and force feedback. By adopting the above-mentioned MEMS gyroscope error suppression method, it further includes:

[0037] A step of performing a proportional transformation on the signal after PI control to obtain an angular velocity signal.

[0038] Beneficial effects

[0039] The zero-bias suppression method for a MEMS gyroscope based on dithering and force feedback according to the present invention has the following beneficial effects compared with the existing zero-bias suppression methods:

[0040] First, the error suppression method of the present invention modulates the gyroscope zero-bias to a high frequency while obtaining the angular velocity through secondary demodulation, and eliminates it through filtering, thereby achieving zero bias. The working principle determines that there is no longer a need for periodic calibration and compensation of the zero-bias, which will greatly save the economic and time costs of user maintenance in practical applications.

[0041] Second, the error suppression method of the present invention proposes a technical route scheme of dithering modulation, which modulates the angular velocity carrier frequency to the detection mode frequency, realizes mode matching under a non-asymmetric structure, and proposes a new technical route for high-precision MEMS gyroscopes; as the maximum angle θ0 of the dithering in the present invention increases, the signal-to-noise ratio increases, which can play a role in suppressing noise.

[0042] Third, the error suppression method of the present invention introduces a force feedback loop to load the force feedback signal to the detection end, so that the generated piezoelectric force cancels out the Coriolis force after modulation, thereby realizing angular velocity force feedback and achieving the purpose of ensuring the sensitivity of the gyroscope while performing dithering modulation. PI control is adopted in the force feedback loop, where the proportional link can immediately respond to the deviation signal of the system and reduce the deviation, and the integral link can eliminate the steady-state error and improve the steady-state performance of the gyroscope.

[0043] Fourth, the error suppression method of the present invention adds dithering modulation and force feedback detection, solves the problem of long-term calibration-free, makes the zero-bias completely eliminated while the angular velocity integration caused by white noise does not diverge; greatly expands the application of MEMS gyroscopes in the field of long-endurance and long-range pure inertial navigation. Description of the drawings

[0044] Figure 1 is a block diagram of the composition of the MEMS gyroscope system in an embodiment of the present invention.

[0045] Figure 2 is a block diagram of the composition of the angular velocity calculation module and the force feedback module of the MEMS gyroscope in an embodiment of the present invention.

[0046] Figure 3It is a schematic diagram of the sensitive structure (tuning fork), the dithering structure, and their installation methods in the embodiments of the present invention.

[0047] Figure 4 It is a dithering schematic diagram of the sensitive structure (tuning fork) of the MEMS gyroscope in the embodiments of the present invention.

[0048] Figure 5 It is a working principle diagram of the MEMS gyroscope in the embodiments of the present invention.

[0049] Figure 6 It is a simulink simulation result diagram of the MEMS gyroscope error suppression method in the embodiments of the present invention.

[0050] Figure 7 It is a flowchart of the MEMS gyroscope error suppression method in the embodiments of the present invention. Detailed implementation manners

[0051] The present invention uses periodic dithering modulation of the sensitive axis of the gyroscope and adds force feedback detection to ensure the sensitivity of the gyroscope while completely eliminating zero-bias calibration and suppressing the angular random walk caused by white noise, realizing non-divergence of angular velocity integration, and expanding the application of MEMS gyroscopes in the field of long-endurance and long-range pure inertial navigation.

[0052] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0053] Embodiment 1

[0054] This embodiment is used to detail the specific implementation manners in which the inventive concept of the present invention is realized by a device.

[0055] As Figure 1 shown, the MEMS gyroscope based on dithering and force feedback in this embodiment includes: a sensitive structure 1, a dithering structure 2, a sensitive structure driving module 3, a dithering driving module 4, a dithering detection module 5, a sensitive structure detection module 6, an angular velocity calculation module 7, and a force feedback module 8.

[0056] Among them, the sensitive structure 1 includes a driving end 11 and a detecting end 12. The sensitive structure driving module 3 is used to generate a first driving voltage to vibrate the driving end 11 of the sensitive structure. The jitter structure 2 is connected to the sensitive structure 1. The jitter driving module 4 is used to generate a second driving voltage to drive the jitter structure 2 to jitter. The jitter of the jitter structure 2 drives the sensitive axis 13 of the sensitive structure 1 to jitter. The jitter structure detecting module 5 is used to detect the jitter modulation signal generated by the jitter of the jitter structure and output the jitter modulation signal S5 to the angular velocity calculating module 7 and the force feedback module 8. The sensitive structure detecting module 6 is used to detect the speed and displacement of the vibration of the driving end of the sensitive structure, output the driving end displacement signal S61 to the angular velocity calculating module 7, output the driving end speed signal S63 to the force feedback module 8, detect the electrical signal of the detecting end of the sensitive structure and output the detection signal S62 to the angular velocity calculating module. The angular velocity calculating module demodulates, filters and performs PI control on the detection signal according to the jitter modulation signal S5 and the driving end displacement signal S61 to obtain the signal after PI control. One way of the signal after PI control is used for the output of the angular velocity signal, denoted as S71, and the other way is output to the force feedback module 8, denoted as S72. The force feedback module 8 is used to obtain the force feedback signal S8 according to the driving end speed signal S63, the jitter modulation signal S5 and the signal S72 after PI control, and apply the force feedback signal S8 to the detecting end of the sensitive structure. The action of the force feedback signal on the sensitive structure cancels the Coriolis force generated by the angular velocity input when there is an angular velocity input, and eliminates the bending of the sensitive structure in the direction of the angular velocity input.

[0057] Further, in this embodiment, as Figure 2 shown, the angular velocity calculating module 7 includes a first multiplier 71, a second multiplier 72, a low-pass filter 73, a frequency doubling notch filter 74, and a PI controller 75. The first multiplier is used to multiply the detection signal S62 by the jitter modulation signal S5 to obtain a first demodulation signal. The second multiplier is used to multiply the first demodulation signal by the driving end displacement signal to obtain a second demodulation signal. The low-pass filter and the frequency doubling notch filter are used to filter the second demodulation signal to eliminate the zero offset and power frequency interference. The PI controller performs PI control on the signal eliminating the zero offset and power frequency interference to obtain the signal after PI control. The force feedback module 8 includes a third multiplier 81 and a fourth multiplier 83. The third multiplier is used to multiply the signal S72 after PI control by the driving end speed signal S63. The fourth multiplier is used to multiply the output of the third multiplier by the jitter modulation signal S5.

[0058] Specifically, the sensitive structure 1 in this embodiment adopts a tuning fork, and the tuning fork is installed on the jitter structure 2. The tuning fork, the jitter structure and their installation methods are as Figure 3 shown. The tuning fork is placed on the jitter structure 2, and the axis 13 of the tuning fork is coaxially installed and fixed with the axis of the jitter structure, keeping relative static. As Figure 4As shown in the figure, the sensitive axis of the tuning fork is the N axis, the driving axis of the tuning fork is perpendicular to the sensitive axis, and the driving axis and the sensitive axis form the tuning fork plane. The static position of the tuning fork is the position where the sensitive axis N is located when the dithering structure has not started working, denoted as the Y axis, and the axis perpendicular to the Y axis in the tuning fork plane is denoted as the X axis. The dithering structure 2 drives the sensitive axis 13 of the tuning fork to perform periodic dithering, that is, to perform periodic dithering with respect to the static position Y axis of the sensitive axis N, and the dithering angle is θ.

[0059] When the MEMS gyroscope is working properly, the driving signal is loaded onto the driving end, causing the tuning fork to vibrate in the tuning fork plane under the action of equal and opposite strain forces along the driving axis direction. This vibration is also called the reference vibration. At the same time, the dithering structure is driven by the driving voltage to generate dithering, driving the dithering of the tuning fork.

[0060] As Figure 5 shown, during operation, at the driving end of the tuning fork, the driving end velocity signal S63 (labeled as the driving velocity signal in the figure) performs the first modulation on the angular velocity sensed by the sensitive axis of the tuning fork to obtain the first modulated signal; then the dithering modulation signal S5 performs the second modulation on the first modulated signal to obtain the second modulated signal; the frequency of the dithering modulation signal is equal to the frequency difference between the detection frequency of the detection end and the driving frequency of the driving end, and the frequency of the second modulated signal is at the detection frequency. At the detection end, the second modulated signal is received by the detection end through the action of the meter head transfer function. In addition, the detection end also receives the zero bias Ω B and the noise Ω n . The function of the meter head transfer function is to perform a 90° phase lag on the signal with a frequency at the detection frequency in the second modulated signal; the detection frequency is the resonant frequency of the detection end. The sensitive structure detects the electrical signal at the detection end to obtain the detection signal, including the second modulated signal passing through the meter head transfer function, the zero bias Ω B and the noise Ω n , and the noise will cause angular random walk of the gyroscope.

[0061] The angular velocity calculation module demodulates the second modulated signal, including the first demodulation and the second demodulation; the dithering modulation signal demodulates the signal received at the detection end for the first time to obtain the first demodulated signal; the driving end displacement signal demodulates the first demodulated signal for the second time to obtain the second demodulated signal; the second demodulated signal is subjected to low-pass filtering and frequency doubling notch filtering to obtain the signal after frequency doubling notch filtering; the signal after frequency doubling notch filtering is subjected to PI control to obtain the signal after PI control; the PI control performs amplitude and phase control on the signal after frequency doubling notch filtering; the signal after PI control is subjected to proportional transformation to obtain the angular velocity; the proportional transformation multiplies the signal after PI control by the proportionality factor; the signal after PI control is passed through the force feedback loop to obtain the force feedback signal; the force feedback signal acts on the detection end.

[0062] The simulink simulation results of this embodiment are as follows Figure 6 As shown, Figure 6 From top to bottom, the first waveform is the angular velocity, the second waveform is the signal after PI control, the third waveform is the demodulation result of the angular velocity, and the fourth waveform is the integral result of the demodulation result of the angular velocity. It can be seen from the figure that the demodulation result of the angular velocity has no DC component and is only affected by noise, indicating that the zero bias is eliminated. The integral result range of the demodulation result of the angular velocity is between 0 and 0.07, indicating that the random walk of the angle caused by white noise is suppressed, and the angular velocity integral is non-divergent.

[0063] The present invention adopts jitter modulation to obtain angular velocity, and the process is a secondary demodulation process. While obtaining the angular velocity, the gyroscope zero bias is modulated to a high frequency, and then the zero bias modulated to the high frequency is eliminated through low-pass filtering.

[0064] The detection modal vibration caused by the Coriolis effect is detected by the change in the sensitive capacitance of the gyroscope. This capacitance change will be extracted, amplified and processed by the detection circuit to characterize the angular velocity. An indicator is needed to evaluate the ability of the output signal to sense the Coriolis effect. This indicator is called sensitivity, which is defined as the rate of change of the voltage output signal and the input angular velocity. Sensitivity is a very important indicator of the gyroscope. High sensitivity can greatly improve the zero-bias performance of the gyroscope. The present invention sets the frequency of the MEMS gyroscope drive mode and the frequency of the detection mode to be similar or equal, so that the frequency of the jitter modulation signal is close to or equal to the frequency difference between the detection frequency and the driving frequency, and uses the resonance amplification of the tuning fork to improve the sensitivity. The gyroscope has the highest sensitivity.

[0065] The present invention uses force feedback to make the feedback piezoelectric force and the modulated Coriolis force cancel each other out, suppress the angle random walk caused by white noise, and achieve non-divergence of angular velocity integral.

[0066] Example 2

[0067] This embodiment describes in detail a specific implementation method of the inventive concept of the present invention using a method.

[0068] like Figure 7 As shown, the MEMS gyroscope error suppression method based on jitter and force feedback of the present invention comprises the steps of:

[0069] S1, a step of starting the MEMS gyroscope; the MEMS gyroscope has a shaking structure and a sensitive structure, the sensitive structure includes a driving end and a detection end, after the MEMS gyroscope is started, the driving end of the sensitive structure is driven by a first driving voltage to make the sensitive structure vibrate around its sensitive axis, the angular velocity to be measured is modulated by the vibration of the driving end, and the shaking structure is driven by a second driving voltage to shake while driving the sensitive axis of the sensitive structure to shake;

[0070] S2, a step of obtaining a dither modulation signal generated by dithering of a dither structure;

[0071] S3, a step of obtaining a velocity signal and a displacement signal of the driving end of the sensitive structure vibrating;

[0072] S4, a step of obtaining an electrical signal of the detection end of the MEMS gyroscope sensitive structure;

[0073] S5, a step of multiplying the electrical signal of the detection end by the dither modulation signal and then multiplying the result by the displacement signal of the driving end to obtain a demodulation signal;

[0074] S6, a step of performing low-pass filtering and frequency doubling notch filtering on the demodulation signal to eliminate zero bias and power frequency interference;

[0075] S7, a step of performing PI control on the signal after eliminating zero bias and power frequency interference to obtain a signal after PI control;

[0076] S8, a step of multiplying the signal after PI control by the velocity signal of the driving end and then multiplying the result by the dither modulation signal to obtain a force feedback signal;

[0077] S9, a step of applying the force feedback signal to the detection end of the sensitive structure, the action of the force feedback signal on the sensitive structure cancels the Coriolis force generated by the angular velocity input when there is an angular velocity input, and eliminates the bending of the sensitive structure in the direction of the angular velocity input.

[0078] Further, the dither frequency of the dither structure is equal to the difference between the detection frequency of the detection end of the sensitive structure and the driving frequency of the driving end.

[0079] Based on the above MEMS gyroscope error suppression method, the signal after PI control is subjected to proportional transformation to obtain an angular velocity signal, and further becomes the MEMS gyroscope angular velocity measurement method based on dithering and force feedback in an embodiment of the present invention.

[0080] Embodiment 3

[0081] This embodiment details the specific implementation manner of implementing the device and method of the present invention by simulation.

[0082] This embodiment uses simulink to simulate the method of the present invention, and establishes a simulation model based on the Figures 1-5 device and method. The specific steps of implementing the inventive concept of the present invention using the simulation model are as follows:

[0083] S1. Start the MEMS gyroscope. The sensitive structure drive module and the dither drive module start to work, maintaining the stability of the frequency and amplitude of the drive signal. The dither structure drives the sensitive axis of the sensitive structure (tuning fork) to vibrate, and the sensitive structure vibrates around its sensitive axis. The angular velocity Ω is modulated once by the vibration and a second time by the dither. In the simulation, the specific parameters of the angular velocity Ω are set as shown in Table 1:

[0084] Table 1 Parameter settings of angular velocity Ω

[0085]

[0086] The drive - end displacement signal and the drive - end velocity signal are set as shown in Table 2, where ω q is the angular frequency of the drive - end displacement signal and the velocity signal, that is, the drive frequency:

[0087] Table 2 Parameter settings of the drive signal (drive - end displacement signal and drive - end velocity signal)

[0088]

[0089] The drive - end velocity signal Ω qv is modulated with the angular velocity Ω to obtain the signal after the first modulation. The signal after the first modulation includes Ω 0x and Ω 0y :

[0090] Ω 0x = Ω x ×sin(22600πt)

[0091] Ω 0y = Ω y ×sin(22600πt)

[0092] The Ω x is the X - axis component of the angular velocity Ω, and Ω y is the Y - axis component of the angular velocity Ω;

[0093] Ω 0y is the signal of the Y - axis angular velocity component Ω y after the first modulation, and Ω 0x is the signal of the X - axis angular velocity component Ω x after the first modulation;

[0094] The signal after the first modulation is subjected to a second modulation to obtain the signal after the second modulation. The second modulation projects the signal after the first modulation onto the sensitive axis N, and the obtained signal after the second modulation is denoted as Ω1 and Ω2:

[0095]

[0096] Among them, Ω1 is Ω0x Projection on the sensitive axis N, where Ω2 is Ω 0y Projection on the sensitive axis N, θ is the angle between the gyroscope sensitive axis N and the Y axis, and θ = θ0sin(ω d t);

[0097] The θ0sin(ω d t) is the dither modulation signal, and the specific parameter settings are shown in Table 3; θ0 is the maximum angle of dither, ω d is the dither angular frequency, and ω d = ω j - ω q That is, the frequency of the dither modulation signal is equal to the frequency difference between the detection frequency and the drive frequency; the detection frequency ω j = ω d + ω q = 22720π, which is the resonant frequency of the detection end;

[0098] Table 3 Parameter settings of the dither modulation signal

[0099]

[0100] The frequency of the signal after the second modulation is located at ω d + ω q That is, at the detection frequency, the detection end operates at its resonant frequency, thereby achieving the purpose of improving the sensitivity of the gyroscope;

[0101] S2. At the detection end, the signal after the second modulation is received by the detection end through the action of the meter head transfer function. In addition, the detection end also receives the zero bias ΩB and the noise Ωn. The signal received by the detection end is Ω out , denoted as:

[0102] The and are the signals after the signal after the second modulation changes through the meter head transfer function. The detection frequency ω j = ω d + ω q = 22720π, that is, the frequency of the dither modulation signal is equal to the frequency difference between the detection frequency and the drive frequency; the frequency of the signal after the second modulation located at ω j has a 90° phase lag after passing through the meter head transfer function, and ω q ≈ ω j , so the frequency component sin(22600πt) of the drive end speed signal in the signal after the second modulation has a 90° phase lag, and its form becomes -cos(22600πt), which is in-phase and equal in amplitude and opposite in phase to the drive end displacement signal cos(22600πt). Therefore, the signal after the second modulation becomes after passing through the meter head transfer function:

[0103]

[0104] Multiply the dither modulation signal by the received signal at the detection end for the first demodulation to obtain the signal after the first demodulation;

[0105] After the first demodulation, the zero offset Ω in the received signal at the detection end B is multiplied by 6sin(120πt) so that the zero offset Ω B is modulated to 120π;

[0106] Multiply the displacement signal at the driving end by the signal after the first demodulation for the second demodulation to obtain the signal after the second demodulation;

[0107] After the second demodulation, the signal after the first demodulation is multiplied by the displacement signal cos(22600πt) at the driving end, so that the zero offset Ω modulated to 120π by S4 B is further modulated to the frequency of 120π±22600π;

[0108] At this point, after the second demodulation, the zero offset Ω B is modulated to the frequency of 120π±22600π, and this modulated zero offset is called the high-frequency zero offset;

[0109] Filter the signal after the second demodulation with a low-pass filter whose cut-off frequency is lower than 120π to filter out the high-frequency zero offset and other high-frequency terms with frequencies higher than 120π to obtain the signal after zero offset elimination; then filter out the power frequency interference;

[0110] The signal after zero offset elimination is:

[0111]

[0112] Perform PI control on the signal after zero offset elimination to obtain the signal after PI control. The PI control performs amplitude and phase control on the signal after zero offset elimination; the signal after PI control includes an angular velocity term and a noise term; the angular velocity term is equal in amplitude and opposite in phase to the angular velocity Ω; the noise term is the noise after PI control;

[0113] Perform a proportional transformation on the signal after PI control as the demodulated angular velocity; the proportional transformation multiplies the signal after PI control by the proportional factor -1;

[0114] The signal after PI control passes through a force feedback module to obtain a force feedback signal and acts on the detection end of the sensitive structure; the force feedback signal acts on the detection end to monitor and control the deviation signal and eliminate the steady-state error, realizing the correct demodulation and stable output of the angular velocity, and at the same time suppressing the noise Ω nResulting angular random walk; thus, the zero-bias suppression method for MEMS gyroscopes based on dithering and force feedback is completed.

[0115] The error suppression method of the present invention modulates the gyroscope zero-bias to a high frequency while obtaining the angular velocity through secondary demodulation, and eliminates it through filtering, thereby achieving zero zero-bias. The working principle determines that there is no longer a need for periodic calibration and compensation of the zero-bias, which will greatly save the economic and time costs of user maintenance in practical applications.

[0116] The error suppression method of the present invention proposes a technical route solution using dither modulation, modulates the angular velocity carrier frequency to the detection mode frequency, realizes mode matching under a non-asymmetric structure, and proposes a new technical route for MEMS gyroscopes to achieve high precision; as the maximum angle θ0 of the dither increases in the present invention, the signal-to-noise ratio increases, which can play a role in suppressing noise.

[0117] The error suppression method of the present invention introduces a force feedback loop to load the force feedback signal to the detection end, so that the generated piezoelectric force cancels out the Coriolis force after modulation, thereby realizing angular velocity force feedback and achieving the purpose of ensuring the sensitivity of the gyroscope while performing dither modulation. PI control is used in the force feedback loop, where the proportional link can immediately respond to the deviation signal of the system and reduce the deviation, and the integral link can eliminate the steady-state error and improve the steady-state performance of the gyroscope.

[0118] The error suppression method of the present invention adds dither modulation and force feedback detection, solves the problem of long-term calibration-free, makes the zero-bias completely eliminated while the angular velocity integration caused by white noise does not diverge; greatly expands the application of MEMS gyroscopes in the field of long-endurance and long-range pure inertial navigation.

[0119] The above are only the preferred embodiments of the invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the ideological principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A jitter and force feedback based MEMS gyroscope, characterized in that Including: A sensitive structure, a sensitive structure driving module, a sensitive structure detecting module, a dithering structure, a dithering driving module, a dithering structure detecting module, an angular velocity calculating module, and a force feedback module; wherein, The sensitive structure includes a driving end and a detecting end, and the sensitive structure driving module is used to generate a first driving voltage to vibrate the driving end of the sensitive structure; The dithering structure is connected to the sensitive structure, and the dithering driving module is used to generate a second driving voltage to drive the dithering structure to dither, and the dithering of the dithering structure drives the sensitive axis of the sensitive structure to dither; The dithering structure detecting module is used to detect the dithering modulation signal generated by the dithering of the dithering structure, and output the dithering modulation signal to the angular velocity calculating module and the force feedback module; The sensitive structure detecting module is used to detect the velocity and displacement of the vibration of the driving end of the sensitive structure, output the driving end displacement signal to the angular velocity calculating module, output the driving end velocity signal to the force feedback module, detect the electrical signal of the detecting end of the sensitive structure, and output the detection signal to the angular velocity calculating module; The angular velocity calculating module demodulates, filters and performs PI control on the detection signal according to the dithering modulation signal and the driving end displacement signal to obtain a signal after PI control, and uses one path of the signal after PI control as the angular velocity signal and outputs the other path to the force feedback module; The force feedback module is used to obtain a force feedback signal according to the driving end velocity signal, the dithering modulation signal and the signal after PI control, and apply the force feedback signal to the detecting end of the sensitive structure to cancel the Coriolis force generated by the angular velocity input when there is an angular velocity input.

2. The MEMS gyroscope according to claim 1, characterized in that, The angular velocity calculating module includes a first multiplier, a second multiplier, a low-pass filter, a frequency doubling notch filter, and a PI controller; The first multiplier is used to multiply the detection signal by the dithering modulation signal to obtain a first demodulation signal; The second multiplier is used to multiply the first demodulation signal by the driving end displacement signal to obtain a second demodulation signal; The low-pass filter and the frequency doubling notch filter are used to filter the second demodulation signal to eliminate zero bias and power frequency interference; The PI controller performs PI control on the signal after eliminating zero bias and power frequency interference to obtain a signal after PI control.

3. The MEMS gyroscope according to claim 1, wherein The force feedback module includes a third multiplier and a fourth multiplier; The third multiplier is used to multiply the signal after PI control by the driving end velocity signal; The fourth multiplier is used to multiply the output of the third multiplier by the dithering modulation signal.

4. The MEMS gyroscope according to claim 1, wherein The step of using one path of the signal after PI control as the angular velocity signal is to perform a proportional transformation on the signal after PI control to obtain the angular velocity signal.

5. The MEMS gyroscope according to any one of claims 1-4, characterized in that, The dithering frequency of the dithering structure is equal to the difference between the detection frequency of the detecting end of the sensitive structure and the driving frequency of the driving end.

6. A method for suppressing errors of a MEMS gyroscope based on dithering and force feedback, including the steps of: Steps for starting the MEMS gyroscope; the MEMS gyroscope has a dithering structure and a sensitive structure, the sensitive structure includes a driving end and a detecting end, after the MEMS gyroscope is started, the driving end of the sensitive structure is driven by a first driving voltage to vibrate the sensitive structure around its sensitive axis, the angular velocity to be measured is modulated by the vibration of the driving end, and at the same time, the dithering structure is driven by a second driving voltage to dither and drive the sensitive axis of the sensitive structure to dither; Steps for obtaining the dithering modulation signal generated by the dithering of the dithering structure; Steps for obtaining the velocity signal and displacement signal of the driving end of the sensitive structure; Steps for obtaining the electrical signal of the detection end of the sensitive structure of the MEMS gyroscope; Steps for multiplying the electrical signal of the detection end by the dither modulation signal and then multiplying the result by the displacement signal of the driving end to obtain a demodulation signal; steps for performing low-pass filtering and frequency doubling notch filtering on the demodulation signal to eliminate zero bias and power frequency interference; Steps for performing PI control on the signal after eliminating zero bias and power frequency interference to obtain a signal after PI control; Steps for multiplying the signal after PI control by the velocity signal of the driving end and then multiplying the result by the dither modulation signal to obtain a force feedback signal; Steps for applying the force feedback signal to the detection end of the sensitive structure, where the force feedback signal acts on the sensitive structure to counteract the Coriolis force generated by the angular velocity input when there is an angular velocity input.

7. The MEMS gyroscope error suppression method according to claim 6 further includes: The dither frequency of the dither structure is equal to the difference between the detection frequency of the detection end of the sensitive structure and the driving frequency of the driving end.

8. A method for measuring the angular velocity of a MEMS gyroscope based on dithering and force feedback, characterized in that Adopting the MEMS gyroscope error suppression method as described in claim 6 or 7, further comprising: Steps for performing proportional transformation on the signal after PI control to obtain an angular velocity signal.

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