MEMS galvanometer scanning method and laser radar system

Abstract

The invention belongs to the technical field of laser radar scanning control, and discloses an MEMS galvanometer scanning method and a laser radar system.The method comprises the steps that firstly, an electrostatic drive MEMS galvanometer dynamic model with external disturbance is established, and a self-adaptive nonsingular terminal sliding mode controller based on a nonlinear extended state observer is constructed; therefore, trajectory tracking control of the MEMS galvanometer is realized. The laser radar system comprises a laser, an MEMS galvanometer, a driving circuit, a voltage amplifier, a controller based on an FPGA, a position sensor and the like, and realizes accurate trajectory tracking control of a laser beam based on an MEMS galvanometer scanning method. According to the MEMS galvanometer scanning method, the system state can be converged to the sliding mode surface within the limited time through the self-adaptive nonsingular terminal sliding mode controller, the problem of singular values is avoided, the stability and precision of the MEMS galvanometer during tracking of the scanning track are guaranteed, and the laser radar imaging quality can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radar scanning control, and in particular relates to a MEMS galvanometer scanning method and a laser radar system. Background Art

[0002] LiDAR is widely used in target detection and autonomous driving. It emits lasers and receives signals reflected from targets to accurately obtain the distance and speed of targets. MEMS galvanometer is the core scanning device in the LiDAR system, which can deflect and control the laser beam. The electrostatically driven MEMS galvanometer consists of several parts, such as mirror, torsion rod, drive electrode and support structure, and has the advantages of fast response speed and low energy consumption.

[0003] Scanning technology based on MEMS galvanometers greatly affects important indicators of LiDAR, such as field of view, scanning speed, and imaging effect. Therefore, high-precision scanning control methods of MEMS galvanometers are crucial to ensure high-quality imaging of LiDAR. However, precise control of MEMS galvanometers faces many challenges in fast scanning and dynamic environments. Since the LiDAR system has extremely high requirements for the scanning performance of MEMS galvanometers when working, the overshoot of MEMS galvanometers under conventional open-loop control is large and the adjustment time is long, resulting in the transient performance of MEMS galvanometers under conventional open-loop control being difficult to meet the requirements of high-precision scanning performance.

[0004] In addition, the electrostatically driven MEMS galvanometer drives the mirror to twist by applying voltage to the bottom driving electrode to achieve laser deflection. However, the driving voltage of the MEMS galvanometer is nonlinearly related to the twist angle, which makes it difficult for the reflected laser to scan the target along the desired trajectory. Although PID control is easy to implement as a traditional closed-loop control method, it is difficult to handle the nonlinear dynamics of the MEMS galvanometer, especially when scanning at high speed or over a large range. It is prone to response lag and reduced accuracy, and has poor robustness to external disturbances, resulting in deviations in the reflected laser beam and affecting the imaging effect. Therefore, it is difficult to meet the performance requirements of high-precision scanning in LiDAR applications.

[0005] Although first-order sliding mode control is an effective robust control strategy, its jitter problem will affect the scanning accuracy. In the detection of high-speed, dynamically moving targets, the existing galvanometer scanning control technology is difficult to meet the requirements of high precision and robustness, which restricts the performance of the lidar system. On the other hand, there are model parameter perturbations and external disturbances in practical applications, which will have an adverse effect on the control effect. Most traditional control methods rely on accurate system models and have problems such as poor anti-interference ability. Factors such as model parameter uncertainty and external disturbances will bring difficulties to the precise control of MEMS galvanometers.

[0006] Therefore, a MEMS galvanometer scanning method is urgently needed to achieve accurate tracking and scanning of the desired trajectory by the MEMS galvanometer. Summary of the invention

[0007] The purpose of the present invention is to propose a MEMS galvanometer scanning method, which adopts an adaptive non-singular terminal sliding mode control strategy based on a nonlinear extended state observer, and can solve the problem of precise scanning control of a MEMS galvanometer under parameter uncertainty and disturbance during high-frequency and large-range scanning.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme: A MEMS galvanometer scanning method comprises the following steps: Step 1. Establish a dynamic model of an electrostatically driven MEMS galvanometer with external disturbances; Step 2. For the electrostatically driven MEMS galvanometer dynamics model established in step 1, an adaptive non-singular terminal sliding mode controller based on a nonlinear extended state observer is constructed. The construction process includes the design of a nonlinear extended state observer, a non-singular terminal sliding mode design based on reaching law technology, and an adaptive control design. Step 3. Use the adaptive non-singular terminal sliding mode controller to realize the trajectory tracking control of the MEMS galvanometer.

[0009] In addition, based on the above-mentioned MEMS galvanometer scanning method, the present invention also proposes a laser radar system. The LiDAR system includes a laser, a MEMS galvanometer, an FPGA-based controller, a position sensor, and a drive circuit; A reflective mirror surface for adjusting the laser light path is arranged between the laser light source and the MEMS galvanometer; A readable storage medium is stored in the FPGA-based controller, and when the readable storage medium is executed, it is used to implement the steps of the MEMS galvanometer scanning method described above; The position sensor inputs the detected galvanometer torsion position signal and the desired reference position signal into the FPGA card of the FPGA-based controller in real time. The FPGA card outputs a voltage control signal after calculation according to the MEMS galvanometer scanning control method. The driving voltage is amplified by the voltage amplifier of the driving circuit and then input into the bottom and side driving electrodes to drive the MEMS galvanometer to track the desired trajectory for scanning. The light beam reflected by the target is received by the APD detector and the time is recorded, which is used to measure the distance of each light spot from the transmitter according to the lidar time-of-flight ranging method.

[0010] In addition, based on the above-mentioned MEMS galvanometer scanning method, the present invention also proposes a computer-readable storage medium on which a program is stored; when the program is executed by a processor, it is used to implement the steps of the above-mentioned MEMS galvanometer scanning method.

[0011] The present invention has the following advantages: As described above, the present invention relates to a MEMS galvanometer scanning method. Compared with the control strategy under traditional fixed control gain such as PID, the method of the present invention introduces adaptive technology, which can automatically adjust the control gain according to the disturbance change to improve the scanning tracking accuracy. In addition, the method of the present invention also adopts a non-singular terminal sliding mode design scheme, which effectively avoids the singularity problem of conventional terminal sliding mode control under certain conditions, and ensures that the galvanometer scanning process will not cause the galvanometer to have unstable control problems due to singularity problems. In addition, the method of the present invention also introduces a switching control law, so that the system state has a faster approach speed when it is far away from the sliding surface, and the control law will gradually decrease and suppress the jitter phenomenon when approaching the sliding surface of the system. The nonlinear extended state observer designed by the present invention can accurately estimate the disturbances existing in the system, and effectively reduce the gain of the switching control law through compensation, thereby further suppressing the jitter phenomenon. The MEMS galvanometer scanning method of the present invention adopts the robust nonlinear strategy of sliding mode control. Through the adaptive non-singular terminal sliding mode controller, the system state can converge to the sliding mode surface within a finite time. It is more suitable for the precise scanning control of the MEMS galvanometer in laser radar applications, and does not rely on the precise model parameters of the system. It can enable the MEMS galvanometer to maintain high precision and stability in large-angle and fast scanning under the condition of disturbance, which is beneficial to improving the quality of laser radar imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Flow chart of the MEMS galvanometer scanning method in an embodiment of the present invention.

[0013] Figure 2 for , Schematic diagram of the scanning effect of the MEMS galvanometer controlled by the PID control algorithm.

[0014] Figure 3 for , A schematic diagram of the scanning effect of a MEMS galvanometer controlled by the MEMS galvanometer scanning method of the present invention is shown in FIG.

[0015] Figure 4 for , Schematic diagram of the disturbance estimation effect using the method of the present invention.

[0016] Figure 5 for , Schematic diagram of the scanning effect of the MEMS galvanometer controlled by the PID control algorithm.

[0017] Figure 6 for , A schematic diagram of the scanning effect of a MEMS galvanometer controlled by the MEMS galvanometer scanning method of the present invention is shown in FIG.

[0018] Figure 7 for , Schematic diagram of the disturbance estimation effect using the method of the present invention.

[0019] Figure 8 Schematic diagram of a laser radar system based on closed-loop control of an electrostatically driven MEMS galvanometer in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Example 1 In view of the fact that MEMS laser radar applications require not only accurate trajectory tracking performance but also anti-interference and other performance requirements, this embodiment proposes an adaptive non-singular terminal sliding mode control MEMS galvanometer scanning method based on a nonlinear extended state observer to solve the difficult problems faced by traditional control methods. It adopts robust control that does not rely on an accurate system model, and designs a nonlinear extended state observer to estimate unknown disturbances in the system. It introduces adaptive technology to estimate the upper bound information of the disturbance to suppress the chattering problem of the sliding mode control, and adopts the approach rate technology to improve the approach speed of the system state and suppress the chattering problem. The MEMS galvanometer scanning method of the present invention can make the closed-loop system state converge within a finite time in the presence of external disturbances, improve the response speed and tracking accuracy of the MEMS galvanometer scanning control, and thus improve the scanning performance in laser radar applications.

[0021] like Figure 1 As shown, the MEMS galvanometer scanning method in this embodiment specifically includes the following steps: Step 1. Establish a dynamic model of an electrostatically driven MEMS galvanometer with external disturbances.

[0022] The electrostatically driven MEMS galvanometer includes a mirror, two pairs of torsion rods, a support frame, a frame, and a driving electrode. By applying a corresponding voltage to the driving electrode, the galvanometer can be twisted around the X-axis and Y-axis. The mathematical model of the MEMS galvanometer is expressed as: .

[0023] in, and Respectively represent the galvanometer along Axis direction and The torsion angle about the axis, and is the moment of inertia, and is the damping coefficient, and is the spring constant of the torsion bar, and is the electrostatic torsional torque.

[0024] and Respectively expressed as: .

[0025] .

[0026] in, represents the silicon density, represents the mirror thickness, Indicates the width and length of the mirror, Indicates the outer width of the frame, Indicates the external length of the frame, Indicates the internal width of the frame, Indicates the internal length of the frame.

[0027] and Respectively expressed as: .

[0028] .

[0029] in, , and represents the electrostatic torque generated by the bottom driving electrode attracting the mirror, , and represents the electrostatic torque caused by the side driving electrode attracting the mirror; Represents the electrostatic torque generated by the bottom driving electrode attracting the frame. and Has the following form: .

[0030] .

[0031] in, is the dielectric constant of air, and denote the integration areas of the bottom driving electrode and the side driving electrode, respectively. , Represents the distance between the bottom driving electrode and the mirror. The control voltage applied to the driving electrode is as follows: .

[0032] in, is the bias voltage, and They represent the control voltages of the electrostatically driven MEMS galvanometer in the X-axis and Y-axis directions respectively.

[0033] definition , , , , , the dynamic model of electrostatically driven MEMS galvanometer is transformed into: .

[0034] in, , , , , is the system model parameter. , , , , . , Respectively represent the control of the micromirror along , The driving voltage for the angle twist.

[0035] Considering external disturbances, the dynamic model of the electrostatically driven MEMS galvanometer with external disturbances is expressed as: .

[0036] in, is the state variable of the MEMS galvanometer system, is the control input of the system, is the system output, is a bounded disturbance, satisfying , Represents the upper bound of unknown external disturbances. , , , is the system matrix, which can be expressed as: , , , .

[0037] Step 2. For the electrostatically driven MEMS galvanometer dynamic model established in step 1, an adaptive non-singular terminal sliding mode controller based on a nonlinear extended state observer is constructed. The construction process includes the design of a nonlinear extended state observer, a non-singular terminal sliding mode design based on reaching law technology, and an adaptive control design.

[0038] Step 2.1. Design a nonlinear extended state observer to estimate the unknown disturbance in the MEMS galvanometer system.

[0039] make is the extended state variable, ,definition , and assuming there is a positive scalar Make ;definition , and then rewrite the dynamic model of the electrostatically driven MEMS galvanometer with external disturbance as follows: .

[0040] in, , , , is the system matrix, which can be expressed as: , , , .

[0041] According to the dynamic model of electrostatically driven MEMS galvanometer with external disturbance, the nonlinear extended state observer is designed as follows: .

[0042] in, is the observer state, , , , They are , , The estimated value of the state; is the observer gain, , , , They are , , Observer parameters of ; , is a constant; is a nonlinear function, defined as: .

[0043] in, is a constant, satisfying When the system estimate is close to the system state, the nonlinear function It can improve the observation performance of the state nonlinear extended state observer.

[0044] Designing the observer gain Make is Hurwitz, that is, there exists a positive definite matrix is the Lyapunov equation The solution of represents the identity matrix, then there exists a symmetric positive definite matrix So that: .

[0045] in, is a suitably symmetric positive definite matrix.

[0046] Defining the estimation error of the nonlinear extended state observer for: .

[0047] in, , , , , They are , , The state estimation error of the nonlinear extended state observer is expressed as: .

[0048] in: .

[0049] This embodiment also introduces the Lyapunov function , to prove the effectiveness of the designed nonlinear extended state observer.

[0050] .

[0051] right Taking the derivative, we get: .

[0052] in, . and are the maximum and minimum eigenvalues ​​of the matrix respectively. satisfy: .

[0053] get , estimated error It converges to a radius of within the tight set.

[0054] Step 2.2. Design a terminal sliding mode controller based on the disturbance estimate so that the system state output Able to accurately track the reference signal within a limited time.

[0055] Defining Error for: ,in represents the expected signal. Design of fast non-singular terminal sliding surface based on reaching law technology for: .

[0056] Among them, the parameters , and is a positive value, is a constant, satisfying , is a symbolic function. Define the Lyapunov function for: .

[0057] Once the system state reaches the sliding surface, ,get .

[0058] right Taking the first-order differential we get: .

[0059] in, , get when When, error It can converge to zero in a finite time along the non-singular terminal sliding surface from any initial position. Taking the first-order differential, we get: .

[0060] No disturbance considered ,make ,get: .

[0061] Depend on get: .

[0062] Will Substituting into the above formula, we get: .

[0063] Therefore, the sliding mode equivalent control law is designed for: .

[0064] in, represents the disturbance estimate.

[0065] Introducing adaptive parameters and the disturbance estimate , switching control law Designed for: .

[0066] in, , , , is a constant, satisfying , , , .

[0067] The terminal sliding mode controller is designed as: .

[0068] When the system state is far away from the sliding surface, that is, ,pass and Together, they improve the approach speed of the system state. When the system state approaches the sliding surface, , the approaching speed of the system state will gradually decrease to suppress the chattering phenomenon.

[0069] Step 2.3. Introduce adaptive control technology to estimate the upper bound information of the disturbance. Through adaptive control technology, the control can suppress the disturbance in the system without overestimating the gain, and then obtain an adaptive non-singular terminal sliding mode controller based on the nonlinear extended state observer.

[0070] Adaptive parameters Designed for: .

[0071] in, is the adaptive gain, This design can estimate the disturbance through adaptive parameters and weaken the chattering phenomenon in sliding mode control.

[0072] Combining the sliding mode equivalent control law with the switching control law, the adaptive non-singular terminal sliding mode controller constructed by the method of the present invention has the following form: .

[0073] definition , , define the error for: , the stability proof of step 2.1 shows that the perturbation estimation error is bounded, .

[0074] After completing the design of the adaptive non-singular terminal sliding mode controller in step 2, this embodiment also performs stability analysis on the MEMS galvanometer controlled by the adaptive non-singular terminal sliding mode controller. The specific process is as follows: Constructing Lyapunov functions for: .

[0075] in, is a constant, satisfying ;right Taking the first-order differential we get: .

[0076] in, .

[0077] Therefore, it is obtained that the system tracking error can reach the terminal sliding surface in a finite time, maintain its motion state on the sliding surface, and then converge to zero along the sliding surface in a finite time.

[0078] Step 3. Use the adaptive non-singular terminal sliding mode controller to realize the trajectory tracking control of the MEMS galvanometer.

[0079] The MEMS galvanometer scanning method of the present invention is oriented to laser radar applications. It is aimed at the system model of the MEMS galvanometer. The control goal is to design a nonlinear extended state observer to estimate the disturbance in the system under the condition of the presence of disturbance, and then design an adaptive non-singular terminal sliding mode control law based on the disturbance estimation value to make the system state quickly and accurately track the expected sinusoidal scanning trajectory, while suppressing the chattering problem, and through the adaptive law, the MEMS galvanometer trajectory tracking error can converge to zero in a finite time. By switching the control law, the system state can quickly reach and stay on the sliding mode surface, and at the same time, the influence of the disturbance on the system can be suppressed. When the system state reaches the sliding mode surface, the sliding mode equivalent control law plays a major role and can maintain the sliding mode motion of the system, thereby realizing the tracking control of the laser beam scanning trajectory in the MEMS galvanometer.

[0080] In the laser radar application scenario controlled by MEMS galvanometer scanning, there is a nonlinear relationship between the driving voltage and the deflection angle of the galvanometer. Conventional control algorithms usually rely on accurate system models, while factors such as model parameter uncertainty and external disturbances make it difficult to accurately control the galvanometer. The present invention adopts sliding mode control, a robust nonlinear strategy that is more suitable for accurate scanning control of MEMS galvanometers in laser radar applications. The adaptive non-singular terminal sliding mode controller designed by the present invention can make the system state converge to the sliding mode surface within a finite time, and will not cause singular value problems. It also introduces adaptive technology to estimate the upper bound information of the disturbance, improve the scanning tracking accuracy, and ensure the stability and accuracy of the tracking scanning trajectory of the MEMS galvanometer, which is beneficial to improving the imaging quality of the laser radar. In addition, the present invention also designs a nonlinear extended state observer for estimating system disturbances, and compensates for system disturbances in the equivalent control law, thereby correspondingly reducing the gain of the switching control law and suppressing the jitter phenomenon. In addition, in order to further suppress chattering, the method of the present invention introduces a new switching control law so that when the system state is far away from the sliding surface, the convergence speed of the system state is improved. When the system state is close to the sliding surface, the switching control law will gradually decrease to suppress the chattering phenomenon.

[0081] In addition, in order to verify the effectiveness of the method proposed in the present invention, the following specific experiments are given.

[0082] Figure 2 and Figure 3 Respectively in , The schematic diagram of the scanning effect of the MEMS galvanometer controlled by the PID control algorithm and the method of the present invention is shown. It can be seen that the method of the present invention has a more accurate scanning effect than the PID control algorithm and will not cause serious chattering problems. Figure 4 For , The schematic diagram of the disturbance estimation effect obtained by the method of the present invention is shown in Figure 1. The observer designed by the present invention can achieve fast and accurate estimation of unknown disturbances. To further verify the control effect, Figure 5 and Figure 6 Respectively in , The schematic diagram of the scanning effect obtained by using the PID control algorithm and the method of the present invention to control the MEMS galvanometer can be seen in , When the scanning method is used, the method of the present invention still has accurate scanning effect and anti-disturbance performance. Figure 7 For , The disturbance estimation effect diagram of the method of the present invention is shown in FIG. , When , the observer designed by the present invention can still estimate the unknown disturbance quickly and accurately.

[0083] It should be noted that the adaptive non-singular terminal sliding mode control in the method of the present invention can also be replaced by a high-order sliding mode control. The high-order sliding mode control is to act on the high-order derivative of the sliding mode by applying the discontinuous control input, which retains the strong robustness of the traditional sliding mode control and weakens the system's chattering phenomenon. In addition, the electrostatic drive mode of the MEMS micromirror can also be replaced by electromagnetic, piezoelectric and other drive modes. The response speed and power consumption of different drive modes have their own advantages and disadvantages. For example, the displacement is usually small under the piezoelectric drive mechanism, making it difficult to achieve large-angle scanning, and the process design is more complicated under the electromagnetic drive mechanism.

[0084] Example 2 This embodiment 2 proposes a laser radar system based on an adaptive non-singular terminal sliding mode control MEMS galvanometer of a nonlinear extended state observer. This system is based on the same inventive concept as the MEMS galvanometer scanning method in embodiment 1. It is based on closed-loop control and achieves precise trajectory tracking and scanning of the laser beam by improving the MEMS galvanometer scanning method.

[0085] The laser radar system includes lasers, MEMS galvanometers, drive circuits, voltage amplifiers, controllers based on field programmable gate arrays (FPGAs), position sensors and other equipment. Figure 8 As shown, the lidar system also includes a receiver.

[0086] The drive circuit is Figure 8 The MEMS torsion micromirror driving circuit includes an analog-to-digital converter DAC, a low-pass filter and an amplifier circuit. The laser preferably uses a He-Ne laser, i.e., a helium-neon laser.

[0087] In this embodiment, a voltage amplifier is used to amplify the four sets of driving voltages and then input them into the corresponding four sets of bottom and side driving electrodes for driving the MEMS galvanometer, so that the MEMS galvanometer moves along , Angle twist.

[0088] Two sets of reflective mirrors are arranged between the laser light source and the MEMS galvanometer for adjusting the laser optical path.

[0089] The controller based on FPGA adopts the adaptive non-singular terminal sliding mode control method and is programmed in the LABVIEW environment and is pre-written into the FPGA card, that is, the executable code is stored in the controller based on FPGA.

[0090] When the FPGA-based controller runs the executable code, the steps of the above-mentioned MEMS galvanometer scanning method can be implemented.

[0091] The galvanometer torsion position signal detected by the position sensor PSD and the desired reference position signal will be input into the FPGA-based controller in real time. After the control algorithm is calculated, the FPGA card will output the corresponding voltage control signal to drive the torsion of the MEMS galvanometer and enable the MEMS galvanometer to track the desired trajectory scanning.

[0092] The receiver uses an APD detector. The light beam reflected by the target is received by the APD detector and the time is recorded. According to the laser radar time-of-flight ranging method, the distance between each light spot and the laser is measured.

[0093] Example 3 This embodiment 3 describes a computer-readable storage medium on which a program is stored. When the program is executed by a processor, it is used to implement the steps of the MEMS galvanometer scanning method in the above embodiment 1.

[0094] The computer-readable storage medium may be an internal storage unit of any device or apparatus with data processing capabilities, such as a hard disk or memory, or an external storage device of any device with data processing capabilities, such as a plug-in hard disk, a smart media card (SMC), an SD card, a flash card, etc., equipped on the device.

[0095] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with the field under the guidance of this specification fall within the essential scope of this specification and should be protected by the present invention.

Claims

1. A MEMS galvanometer scanning method, characterized in that: The steps include: Step 1. Establish a dynamic model of an electrostatically driven MEMS galvanometer with external disturbances; Step 2. For the electrostatically driven MEMS galvanometer dynamics model established in step 1, an adaptive non-singular terminal sliding mode controller based on a nonlinear extended state observer is constructed. The construction process includes the design of a nonlinear extended state observer, a non-singular terminal sliding mode design based on reaching law technology, and an adaptive control design. Step 3. Use the adaptive non-singular terminal sliding mode controller to realize the trajectory tracking control of the MEMS galvanometer.

2. The MEMS galvanometer scanning method according to claim 1, characterized in that: The step 1 is specifically as follows: The dynamic model of electrostatically driven MEMS galvanometer is expressed as: ； in, and Respectively represent the galvanometer along Axis direction and The torsion angle about the axis, and is the moment of inertia, and is the damping coefficient, and is the spring constant of the torsion bar, and is the electrostatic torsional torque; and Respectively expressed as: ； ； in, represents the silicon density, represents the mirror thickness, Indicates the width and length of the mirror, Indicates the outer width of the frame, Indicates the external length of the frame, Indicates the internal width of the frame, Indicates the internal length of the frame; and Respectively expressed as: ； ； in, , and represents the electrostatic torque generated by the bottom driving electrode attracting the mirror, , and represents the electrostatic torque caused by the side driving electrode attracting the mirror; represents the electrostatic torque generated by the bottom driving electrode attracting the frame; and Has the following form: ； ； in, represents the dielectric constant of air, and denote the integration areas of the bottom driving electrode and the side driving electrode, respectively. , represents the distance between the bottom driving electrode and the mirror; The control voltage applied to the driving electrode is as follows: ； in, is the bias voltage, and They represent the control voltages of the electrostatically driven MEMS galvanometer in the X-axis and Y-axis directions respectively; definition , , , , , the dynamic model of electrostatically driven MEMS galvanometer is transformed into: ； in, , , , , are system model parameters, , Respectively represent the control of the galvanometer along , The driving voltage for the angle twist; Considering external disturbances, the dynamic model of the electrostatically driven MEMS galvanometer with external disturbances is expressed as: ； in, is the state variable of the MEMS galvanometer system, is the control input of the system, is the system output, is a bounded disturbance, satisfying , represents the upper bound of unknown external disturbance; , , , is the system matrix, which can be expressed as: ， ， ， 。 3. The MEMS galvanometer scanning method according to claim 2, characterized in that: The step 2 is specifically as follows: Step 2.

1. Design a nonlinear extended state observer to estimate the unknown disturbance in the MEMS galvanometer system. Step 2.

2. Design a terminal sliding mode controller based on the disturbance estimate; Step 2.

3. Introduce adaptive control technology to estimate the upper bound information of the disturbance, and then obtain an adaptive non-singular terminal sliding mode controller based on the nonlinear extended state observer.

4. The MEMS galvanometer scanning method according to claim 3, characterized in that: The step 2.1 is specifically as follows: make is the extended state variable, ,definition , and assuming there is a positive scalar Make ;definition , and then rewrite the dynamic model of the electrostatically driven MEMS galvanometer with external disturbance as follows: ； in, , , , is the system matrix, which can be expressed as: ， ， ， ； According to the dynamic model of electrostatically driven MEMS galvanometer with external disturbance, the nonlinear extended state observer is designed as follows: ； in, is the observer state, , , , They are , , The estimated value of the state; is the observer gain, , , , They are , , Observer parameters of ; , is a constant; is a nonlinear function, defined as: ； in, is a constant, satisfying ; Designing the observer gain , such that there exists a positive definite matrix for The solution of represents the identity matrix, then there exists a symmetric positive definite matrix So that: ； in, is a symmetric positive definite matrix; Defining the estimation error of the nonlinear extended state observer for: ； in, , , , They are , , The state estimation error of The estimation error of the nonlinear extended state observer is expressed as: ； in: 。 5. The MEMS galvanometer scanning method according to claim 4, characterized in that: In step 2.1, after completing the design of the nonlinear extended state observer, the Lyapunov function is also introduced The stability analysis of the nonlinear extended state observer is carried out. The specific process is as follows: ； right Taking the derivative, we get: ； in, ; and are the maximum and minimum eigenvalues ​​of the matrix respectively; when the estimation error satisfy: ； get , estimated error Converges to a radius of within the tight set.

6. The MEMS galvanometer scanning method according to claim 4, characterized in that: The step 2.2 is specifically as follows: Defining Error for ,in Indicates expected signal; Design of fast non-singular terminal sliding surface based on reaching law technique for: ； Among them, the parameters , and is a positive value; is a constant, satisfying ; is a symbolic function; Define the Lyapunov function for: ； When the system state reaches the sliding surface, that is, ,get ; right Taking the first-order differential we get: ； in, ,when When, error It can converge to zero in a finite time along the non-singular terminal sliding surface from any initial position; Taking the first-order differential, we get: ； No disturbance considered ,make ,get: ； Depend on get: ； Substitution ,get: ； Sliding mode equivalent control law Designed for: ； in, represents the disturbance estimate; Introducing adaptive parameters and the disturbance estimate , switching control law Designed for: ； in, , , , is a constant, satisfying , , , ; The terminal sliding mode controller design is obtained as: 。 7. The MEMS galvanometer scanning method according to claim 6, characterized in that: The step 2.3 is specifically as follows: Adaptive parameters Designed for: ； in, is the adaptive gain, is an adjustable parameter; Combining the sliding mode equivalent control law with the switching control law, an adaptive non-singular terminal sliding mode controller is constructed as follows: ； definition , , define the disturbance estimation error for: , we can get the perturbation estimation error to be bounded, .

8. The MEMS galvanometer scanning method according to claim 7, characterized in that: In step 2, after the design of the adaptive non-singular terminal sliding mode controller is completed, the stability analysis of the MEMS galvanometer system controlled by the adaptive non-singular terminal sliding mode controller is also performed. The specific process is as follows: Constructing Lyapunov functions : ； in, is a constant, satisfying ;right Taking the first-order differential we get: ； in, ; The system tracking error can reach the terminal sliding surface within a finite time, maintain its motion state on the sliding surface, and then converge to zero along the sliding surface within a finite time.

9. A laser radar system, comprising a laser, a MEMS galvanometer, a controller based on FPGA, a position sensor, a drive circuit and a receiver; characterized in that: A reflective mirror surface for adjusting the laser light path is arranged between the laser light source and the MEMS galvanometer; A readable storage medium is stored in the FPGA-based controller, and when the readable storage medium is executed, it is used to implement the steps of the MEMS galvanometer scanning method according to any one of claims 1 to 8; The position sensor inputs the detected galvanometer torsion position signal and the desired reference position signal into the FPGA-based controller in real time. The FPGA-based controller outputs a voltage control signal after calculation according to the MEMS galvanometer scanning method. The driving voltage is amplified by the voltage amplifier of the driving circuit and then input into the bottom and side driving electrodes to drive the MEMS galvanometer to track the desired trajectory for scanning. The receiver uses an APD detector. The light beam reflected by the target is received by the APD detector and the time is recorded. It is used to measure the distance of each light spot from the laser according to the lidar time-of-flight ranging method.

10. A computer-readable storage medium having a program stored thereon; characterized in that: When the program is executed by a processor, it is used to implement the steps of the MEMS galvanometer scanning method described in any one of claims 1 to 8.

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