Composite control method of laser galvanometer

Abstract

The invention discloses a compound control method of a laser galvanometer, and belongs to the technical field of laser galvanometer control. The method comprises the following steps: analyzing and establishing a simulation mathematical model of the laser galvanometer motor based on physical characteristics of the laser galvanometer motor; designing an LESO (linear extended state observer) based on the system model of the laser galvanometer motor; lESO and a sliding mode controller are combined, and a composite controller is designed, so that a composite control law of the galvanometer motor system is obtained; a linear expansion state observer is optimized by combining a phase lead network, the performance of the observer is improved, and the performance of a composite controller is optimized; and respectively carrying out stability analysis and proving on the improved LESO and the sliding mode controller in the composite controller. According to the invention, independent setting of the LESO and the sliding mode controller can be improved, the difficulty of practical application is reduced, and high-precision control, quick response and excellent robustness of the laser galvanometer motor system are realized.

Description

Technical Field

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

[0002] LiDAR is widely used in 3D imaging, terrain mapping, and atmospheric monitoring due to its high resolution and high precision. In order to achieve efficient scanning and accurate detection, scanning imaging LiDAR usually needs to be equipped with a scanning system. Among the many scanning technologies, the galvanometer scanning system stands out due to its mature technology, stable performance, and efficient beam deflection capability. With its advantages of large scanning range, high precision, and fast response speed, it has become the core component of the current scanning LiDAR.

[0003] The galvanometer motor is usually in a high-speed motion state, which will generate a lot of mechanical heat and increase the temperature. The increase in temperature will cause the system parameters of the motor to change, thus affecting the system performance in the running state. The traditional control method is PID control, which has become the current mainstream control method due to its simple structure, easy implementation in engineering, and low dependence on the accuracy of the mathematical model of the galvanometer motor. However, it also has some problems, such as poor robustness and complex parameter adjustment process. Therefore, in order to solve the influence of interference and parameter changes on the galvanometer motor, an effective control method is urgently needed. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a composite control method of a laser galvanometer, which realizes high-precision control, fast response and excellent robustness of the laser galvanometer motor system.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A composite control method for a laser galvanometer comprises the following steps:

[0007] Step 1: Analyze and establish a simulation mathematical model of the laser galvanometer motor based on its physical characteristics;

[0008] Step 2: Based on the simulation mathematical model of the laser galvanometer motor, a linear extended state observer is designed to estimate the external total disturbance of the laser galvanometer motor system in real time and feed forward compensation to the controller;

[0009] Step 3: Based on the linear extended state observer and the sliding mode controller, a composite controller is designed to obtain a composite control law of the laser galvanometer motor system;

[0010] Step 4: Optimize the linear extended state observer and composite controller by combining the phase advance network.

[0011] In a second aspect, the present invention further provides a composite control device for a laser galvanometer, comprising:

[0012] A simulation model building unit, used for analyzing and building a simulation mathematical model of the laser galvanometer motor based on the physical characteristics of the laser galvanometer motor;

[0013] An observer design unit is used to design a linear extended state observer based on a simulation mathematical model of the laser galvanometer motor, so as to estimate the external total disturbance of the laser galvanometer motor system in real time and feed forward compensation to the controller;

[0014] A control law calculation unit, used to design a composite controller based on the linear extended state observer and the sliding mode controller to obtain a composite control law for the laser galvanometer motor system;

[0015] The optimization unit is used to optimize the linear extended state observer and the composite controller in combination with the phase advance network.

[0016] In a third aspect, the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned composite control method of a laser galvanometer.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned composite control method of a laser galvanometer.

[0018] The beneficial effects of the present invention are:

[0019] The present invention can not only realize the independent setting of the sliding mode controller and reduce the difficulty of practical application, but also realize the high-precision control, fast response and excellent robustness of the laser galvanometer motor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A diagram of a composite control method of a laser galvanometer according to the present invention;

[0021] Figure 2 Comparison diagram of estimation error between traditional linear extended state observer and improved linear extended state observer. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] The present invention proposes a composite control method for a laser galvanometer, which realizes high-precision control, rapid response and excellent robustness of a laser galvanometer motor system.

[0024] like Figure 1 The figure shows a block diagram of the principle of the method of the present invention, including a hardware platform, analog-to-digital conversion, digital-to-analog conversion, and a galvanometer motor for realizing the improved linear extended state observer and sliding mode controller in the method. The present invention will be described according to the following steps: Step 1: Based on the physical characteristics of the laser galvanometer motor, analyze and establish a simulation mathematical model of the laser galvanometer motor; Step 2: Based on the simulation mathematical model of the laser galvanometer motor, design a linear extended state observer for real-time estimation of the external total disturbance of the laser galvanometer motor system and feedforward compensation to the controller; Step 3: Based on the linear extended state observer and the sliding mode controller, design a composite controller to obtain a composite control law for the laser galvanometer motor system; Step 4: Optimize the linear extended state observer and the composite controller in combination with the phase advance network.

[0025] First, the mathematical model of the galvanometer motor is established based on the armature voltage balance equation, armature mechanical balance equation, torque balance formula, torque-current relationship, and back electromotive force-angular velocity relationship of the galvanometer motor. The equations and mathematical model are as follows:

[0026] (1)

[0027] in, and are the armature voltage and current of the motor stator; and are the stator resistance and stator inductance of the motor; is the back EMF of the motor; and are the electromagnetic torque and load torque of the motor; and are the moment of inertia and the motor viscous damping coefficient; and are the torque coefficient and back EMF coefficient of the motor. t is the time, θ and is the angle and angular velocity of the motor rotor, is a complex frequency variable.

[0028] Generally speaking, the inductance of the galvanometer motor is much smaller than other parameters such as resistance. Therefore, the mathematical model of the motor can be simplified:

[0029] (2)

[0030] According to equations (1) and (2), the equation of the second-order control system of the galvanometer motor can be expressed as:

[0031] (3)

[0032] in, is the output of the galvanometer motor, is the second-order time derivative of the output y of the galvanometer motor, u is the input voltage of the galvanometer motor, is the total external disturbance of the galvanometer motor, are some known parameters of the galvanometer motor;

[0033] Based on the principle of designing a linear extended state observer based on the active disturbance rejection controller, the total external disturbance of the system is expanded into the state variable of the system, and the third-order system equation of the laser galvanometer motor system can be established:

[0034] (4)

[0035] in, , , They are the state variables of the galvanometer motor’s angle, angular velocity, and external total disturbance. , , is the first-order time derivative of the corresponding parameter, are some known parameters of the galvanometer motor, is the first-order time derivative of the total external disturbance of the galvanometer motor.

[0036] According to equations (1) and (2) in step 1, a traditional linear extended state observer can be designed. Through this design method, the linear extended state observer can use the known dynamic characteristics and input and output information of the system to estimate the internal state that cannot be directly measured and the total external disturbance of the system. Its specific form is as follows:

[0037] (5)

[0038] in, They are the state variables of the galvanometer motor angle, galvanometer motor angular velocity and the total external disturbance of the system estimated by the linear extended state observer. is the first-order time derivative of the corresponding parameter, is the error between the estimated angle of the linear extended state observer and the actual angle of the galvanometer motor, , , represents the feedback coefficient of the linear extended state observer, is the observation bandwidth of the linear extended state observer.

[0039] Next, the sliding surface Design:

[0040] (6)

[0041] in, is the sliding surface parameter, , is the error between the estimated angle and the actual angle of the linear extended state observer.

[0042] Derivative of the sliding surface:

[0043] (7)

[0044] in, and are the first and second time derivatives of the corresponding parameters.

[0045] Choose an exponential reaching law:

[0046] (8)

[0047] In the formula, is the switching gain of the sign function, is the approaching rate of the system, ;

[0048] According to equations (6), (7) and (8), the composite control law v of the galvanometer motor system is obtained:

[0049] (9)

[0050] Where: is the desired angle, is the total external disturbance of the system estimated by the composite controller of the galvanometer motor system.

[0051] It can be seen from the composite control law (9) that the control effect of the control law depends on the estimation accuracy of the total external disturbance of the system. Therefore, to improve the control effect of the composite control controller, it is necessary to improve the performance of LESO. Based on this, the phase advance network is introduced to improve the phase delay problem of the state variables estimated by LESO.

[0052] (10)

[0053] In the formula, is an adjustable parameter, , is the time constant, is the output of the phase advance network.

[0054] Figure 2 This is a comparison diagram of the estimation errors of the traditional linear extended state observer and the improved linear extended state observer of the present invention. The above two observers are used to observe a sinusoidal interference signal with an amplitude of 5 and a frequency of 50 Hz. It can be clearly seen that the noise signal delay and amplitude estimated by the improved linear extended state observer are better than those of the traditional linear extended state observer.

[0055] Finally, the stability is proved:

[0056] First, the stability of the improved linear extended state observer is proved. According to equations (5) and (10), we get:

[0057] (11)

[0058] in, , , They are respectively the errors between the state variables of the galvanometer motor angle, angular velocity, and external total disturbance estimated by the improved linear extended state observer and the actual galvanometer motor angle, angular velocity, and external total disturbance.

[0059] According to the typical input analysis method of traditional control theory, let the input , is a step signal with an amplitude of A, and the steady-state error can be obtained:

[0060] (12)

[0061] It can be seen from equation (12) that the improved linear extended state observer can achieve error-free estimation of the installed variables. Next, the stability of the sliding mode controller is proved, and the Lyapunov function of the sliding mode controller is taken as:

[0062] (13)

[0063] According to formula (9) and (13), we can get:

[0064] (14)

[0065] In the formula, is the estimated error of the total disturbance. Combining equations (13) and (14), we can get:

[0066] (15)

[0067] Therefore, the system satisfies the Lyapunov stability criterion. Choose a suitable approach rate and the switching gain factor , so that the system can move to the sliding surface within a finite time.

[0068] In summary, compared with traditional PID control, the present invention designs a composite control method. The improved LESO improves the phase delay problem of the traditional extended state observer in estimating the external total disturbance of the galvanometer motor system. The composite control method solves the problem of slow step response of the laser galvanometer motor with disturbance and parameter disturbance. It can not only realize the independent setting of the sliding mode controller and reduce the difficulty of practical application, but also realize high-precision control, fast response and excellent robustness of the laser galvanometer motor system.

[0069] In a second aspect, the present invention further provides a composite control device for a laser galvanometer, wherein each unit included in the device can linearly carry out each step of the aforementioned method, including:

[0070] A simulation model building unit, used for analyzing and building a simulation mathematical model of the laser galvanometer motor based on the physical characteristics of the laser galvanometer motor;

[0071] An observer design unit is used to design a linear extended state observer based on a simulation mathematical model of the laser galvanometer motor, so as to estimate the external total disturbance of the laser galvanometer motor system in real time and feed forward compensation to the controller;

[0072] A control law calculation unit, used to design a composite controller based on the linear extended state observer and the sliding mode controller to obtain a composite control law for the laser galvanometer motor system;

[0073] The optimization unit is used to optimize the linear extended state observer and the composite controller in combination with the phase advance network.

[0074] In a third aspect, the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned composite control method of a laser galvanometer.

[0075] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned composite control method of a laser galvanometer.

[0076] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite control method for a laser galvanometer, characterized in that: The following steps are involved: Step 1: Analyze and establish a simulation mathematical model of the laser galvanometer motor based on its physical characteristics; Step 2: Based on the simulation mathematical model of the laser galvanometer motor, a linear extended state observer is designed to estimate the external total disturbance of the laser galvanometer motor system in real time and feed forward compensation to the controller; Step 3: Based on the linear extended state observer and the sliding mode controller, a composite controller is designed to obtain a composite control law of the laser galvanometer motor system; Step 4: Optimize the linear extended state observer and composite controller by combining the phase advance network.

2. The composite control method of a laser galvanometer according to claim 1, characterized in that: The step one comprises: The simulation mathematical model of the laser galvanometer motor is established based on the armature voltage balance equation, armature mechanical balance equation, torque balance formula, torque and current relationship, and back electromotive force and angular velocity relationship of the laser galvanometer motor: (1) in, and are the armature voltage and current of the motor stator; and are the resistance and inductance of the motor stator; is the back EMF of the motor; and are the electromagnetic torque and load torque of the motor; and are the moment of inertia and the motor viscous damping coefficient; and is the torque coefficient and back EMF coefficient of the motor, t is the time, θ and is the angle and angular velocity of the motor rotor, is a complex frequency variable.

3. The composite control method of a laser galvanometer according to claim 2, characterized in that: The simulation mathematical model of the laser galvanometer motor is simplified as follows: (2)。 4. The composite control method of a laser galvanometer according to claim 3, characterized in that: The second step comprises: According to equations (1) and (2), the equation of the second-order control system of the laser galvanometer motor is expressed as: (3) in, is the output of the galvanometer motor, is the second-order time derivative of the output y of the galvanometer motor, u is the input voltage of the galvanometer motor, is the total external disturbance of the galvanometer motor, are some known parameters of the galvanometer motor; Based on the principle of designing a linear extended state observer based on the anti-disturbance control, the external total disturbance of the galvanometer motor is Expanded to the state variables of the system, the third-order system equation of the laser galvanometer motor system is established: (4) in, , , They are the state variables of the galvanometer motor’s angle, angular velocity, and external total disturbance. , , is the first-order time derivative of the corresponding parameter, is the first-order time derivative of the total external disturbance of the galvanometer motor; According to equations (1) and (2), the traditional linear extended state observer is designed: (5) in, They are the state variables of the galvanometer motor angle, galvanometer motor angular velocity and the total external disturbance of the system estimated by the linear extended state observer. It corresponds to The first time derivative of is the error between the estimated angle of the linear extended state observer and the actual angle of the galvanometer motor, , , represents the feedback coefficient of the linear extended state observer, is the observation bandwidth of the linear extended state observer.

5. The composite control method of a laser galvanometer according to claim 4, characterized in that: The step three comprises: Design sliding surface : (6) in, is the sliding surface parameter, , is the error between the estimated angle and the actual angle of the linear extended state observer; Derivative of the sliding surface: (7) in, and are the first-order time derivative and the second-order time derivative of the corresponding parameter; Choose an exponential reaching law: (8) In the formula, is the switching gain of the sign function, is the approaching rate of the system, ; According to equations (6), (7) and (8), the composite control law of the galvanometer motor system is obtained: : v (9) In the formula, is the desired angle, is the total external disturbance of the system estimated by the composite controller of the galvanometer motor system.

6. The composite control method of a laser galvanometer according to claim 5, characterized in that: The fourth step comprises: The phase advance network is introduced to improve the phase delay of the state variables estimated by the linear extended state observer according to the following formula: (10) In the formula, is an adjustable parameter, is the time constant, is the output of the phase-advance network.

7. The composite control method of a laser galvanometer according to claim 5, characterized in that: It also includes step 5, respectively analyzing and proving the stability of the linear extended state observer and the sliding mode controller in the composite controller, including: The stability of the improved linear extended state observer is proved by equation (5) and equation (10): (11) in, , , are the errors between the state variables of the galvanometer motor angle, angular velocity, and external total disturbance estimated by the improved linear extended state observer and the actual galvanometer motor angle, angular velocity, and external total disturbance; According to the typical input analysis method of traditional control theory, let the input , is a step signal with amplitude A, and the steady-state error is obtained: (12) The stability of the sliding mode controller is proved, and the Lyapunov function of the sliding mode controller is taken as: (13) According to formula (9) and (13), we can get: (14) In the formula, is the estimated error of the total disturbance. Combining equations (13) and (14), we can get: (15)。 8. A composite control device for a laser galvanometer, characterized in that: include: A simulation model building unit, used for analyzing and building a simulation mathematical model of the laser galvanometer motor based on the physical characteristics of the laser galvanometer motor; An observer design unit is used to design a linear extended state observer based on a simulation mathematical model of the laser galvanometer motor, so as to estimate the external total disturbance of the laser galvanometer motor system in real time and feed forward compensation to the controller; A control law calculation unit, used to design a composite controller based on the linear extended state observer and the sliding mode controller to obtain a composite control law for the laser galvanometer motor system; The optimization unit is used to optimize the linear extended state observer and the composite controller in combination with the phase advance network.

9. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the composite control method of a laser galvanometer as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Executable instructions are stored thereon, and when the instructions are executed by the processor, the processor can implement the composite control method of a laser galvanometer as described in any one of claims 1-7.

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