Discrete time control method and device for photoelectric stabilized platform based on disturbance observer

Abstract

The invention discloses a photoelectric stabilized platform discrete time control method and equipment based on a disturbance observer. The method belongs to the technical field of photoelectric stabilized platform servo control. The method comprises the following steps: establishing an airborne photoelectric stabilized platform current closed loop, a motor and a shafting load model, and introducing a disturbance observer to convert the model into a standard series second-order linear control system; the error amount of the expected speed and the feedback speed and the integral of the error amount are input, and a state variable is determined; based on a generalized standard series discrete second-order linear control system, determining a boundary curve of a phase plane and a controlled quantity linear change region, determining a phase trajectory returning to a zero state for different initial phase points, and obtaining corresponding controlled quantities according to different regions in a motion process; inputting the obtained control quantity and the feedback speed into a disturbance observer, and calculating to obtain a current control quantity; and inputting the current control quantity into a current closed loop, calculating to obtain driving voltage, and inputting the driving voltage into a driving module to drive a motor and a shaft system to rotate.

Description

Technical Field

[0001] This invention belongs to the field of servo control technology for photoelectric stabilization platforms, specifically relating to a discrete-time control method and device for photoelectric stabilization platforms based on a disturbance observer. Background Technology

[0002] The electro-optical stabilization platform is a crucial component of airborne electro-optical reconnaissance equipment. To ensure high-quality imaging of the electro-optical payload carried on the platform, high stability accuracy is required for the platform's servo system. Torque disturbances such as frictional torque and changes in system model parameters are the main factors affecting the stability accuracy of the platform's servo system. In the servo control of the stabilization platform, since acceleration information is directly related to torque, system disturbances can be estimated through acceleration and then compensated for in the control algorithm. The Disturbance Observer (DOB) can obtain acceleration from the angular velocity information of the stabilization platform, observe system disturbances, and compensate for them. However, because it contains a differential element, it suffers from noise amplification and modeling errors, limiting the improvement of servo performance. Typically, a low-pass filter is inserted after the differential element. For traditional closed-loop control schemes, besides introducing disturbance observers, further improving disturbance isolation requires a high bandwidth of the control system. Due to the combined effects of object characteristics, model accuracy, and drive capability, system bandwidth cannot be infinitely high; the closed-loop bandwidth of airborne optoelectronic stabilization platforms is generally no higher than 40Hz. Therefore, traditional controllers offer limited improvement in disturbance rejection capability. Disturbance observers sacrifice system stability margin. If the controller or filter bandwidth is increased, the control system is prone to oscillations or even divergence when there are internal parameter perturbations, external interferences, and internal disturbances. Therefore, further improving disturbance isolation under system bandwidth and numerous constraints has become a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a discrete-time control method and device for an optoelectronic stabilization platform based on a disturbance observer. The method enables the airborne optoelectronic stabilization platform to achieve high stability accuracy and has strong robust anti-interference capabilities even when there are perturbations in the system's internal parameters, external interference, and internal disturbances.

[0004] The method includes the following steps: S1. Build a current closed-loop model of the airborne optoelectronic stabilization platform, motor and shaft load model, and introduce a disturbance observer to transform it into a standard series second-order linear control system. S2. Input the error between the desired speed and the feedback speed, and the integral of the error, to determine the state variables; S3. Based on the standard series-type second-order linear control system, design a discrete-time optimal controller: determine the boundary curve of the phase plane and the linear change region of the control quantity, determine the phase trajectory returning to the zero state for different initial phase points, and obtain the corresponding control quantity according to different regions during the motion process; S4. Input the control quantity and feedback speed obtained in step S3 into the disturbance observer to calculate the current control quantity. S5. Input the current control quantity into the current closed loop, calculate the drive voltage, and input it into the drive module to drive the motor and shaft rotation.

[0005] Furthermore, in the current closed-loop model, motor, and shaft load model of the airborne optoelectronic stabilization platform, the transfer function between the current setpoint and the gyro angular rate feedback is: ,in, Denotes the complex variable in the Laplace transform. Represents the open-loop transfer function. This represents the constant term in the simplified model.

[0006] Furthermore, by introducing a disturbance observer to transform it into a standard series-type second-order linear control system, the current control quantity... and total disturbance Under the influence of the input, the system output is: ;in, This represents the angular rate of the gyroscope in the photoelectric stabilization platform.

[0007] Furthermore, the state variable is ,in, This represents the error between the expected speed and the feedback speed. Indicates will The position state is obtained by integration.

[0008] Furthermore, the boundary curves of the phase plane and the linear variation region of the control quantity are determined, specifically as follows: Based on the architecture of a standard series-type second-order linear control system Obtain the ability to make the system transition from any state Time-optimal control law to zero state ,in, and In This indicates the operation of finding the first derivative; ; express Output limiting, for Discretization using the trapezoidal rule yields the discrete equations of the controlled object: ; in, Represents the number of discrete-time beats. This indicates the control sampling period value; The boundary curve of the phase plane and the linear variation region of the control quantity are determined as follows. and A parallelogram formed by two sets of parallel lines, wherein... This indicates the control sampling period value.

[0009] Furthermore, for different initial phase points, the phase trajectory returning to the zero state is determined, and the corresponding control quantities are obtained according to different regions during the motion process, specifically as follows: Construct three functions to determine the intersection of boundary conditions: , , ; When the initial state The location is within a parallelogram, and the control parameters are: ; When the initial state is not located within the parallelogram, the following cases apply: when At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; in , .

[0010] Furthermore, the disturbances experienced by the computational system in the disturbance observer for: ;in, Represents the corresponding discrete-time number of beats System feedback speed at that time The speed sampling period is used to feed the compensation amount forward to the output to obtain the current control amount. , .

[0011] The beneficial effects of the method described in this invention are as follows: Discrete-time optimal control uses optimal response time as a constraint. When the photoelectric stabilization platform system is subjected to disturbances, it can recover and converge to its original state in the shortest possible time. Traditional controllers, on the other hand, try to shorten the response recovery time by increasing the control bandwidth, but this is physically limited and may cause system oscillations or even divergence. The discrete-time optimal controller enables the system to resist disturbances in the shortest possible time while ensuring system stability. Attached Figure Description

[0012] Figure 1 This is a block diagram of the control system on the airborne optoelectronic stabilization platform in an embodiment of the present invention; Figure 2 This is a phase trajectory diagram of discrete-time optimal control in an embodiment of the present invention; Figure 3 This is the open-loop amplitude-phase characteristic curve of the controlled object in an embodiment of the present invention; Figure 4 This is a comparison diagram of the open-loop amplitude-frequency curves of the simplified model after identification and the actual model in the embodiments of the present invention. Detailed Implementation

[0013] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0014] Example 1 This embodiment provides a discrete-time optimal control method for an airborne optoelectronic stabilization platform based on a disturbance observer. During the inertial stabilization process of the airborne optoelectronic stabilization platform, a method incorporating a discrete-time optimal controller, a disturbance observer, and a current loop control method is constructed. This method includes: Step 1: Build the current closed loop, motor and shaft load model of the airborne optoelectronic stabilization platform, and introduce a disturbance observer to transform it into a standard series second-order linear control system. Step 2: Input the error between the desired speed and the feedback speed, and the integral of the error, to determine the state variables; Step 3: Based on the generalized standard series discrete second-order linear control system, determine the boundary curves of the phase plane and the linear change region of the control quantity. For different initial phase points, determine the phase trajectory that returns to the zero state. During the motion, obtain the corresponding control quantity according to different regions. Step 4: Input the control quantity and feedback speed obtained in Step 3 into the disturbance observer to calculate the current control quantity; Step 5: Input the current control quantity into the current closed loop, calculate the drive voltage, and input it into the drive module to drive the motor and shaft rotation.

[0015] Step 1 specifically involves the control system block diagram on the airborne optoelectronic stabilization platform, as shown below. Figure 1 As shown, the motor and shaft load of the airborne optoelectronic stabilization platform adopt current loop control. After simplification, the transfer function between the system current setpoint and the gyroscope angular rate feedback under disturbance-free conditions is: ,in, Denotes the complex variable in the Laplace transform. Represents the open-loop transfer function. This represents the constant term in the simplified model.

[0016] The torque disturbance and system model parameter changes experienced by the photoelectric stabilization platform can be equivalent to the total disturbance. In current control quantity and total disturbance Under the influence of the input, the system output is: ,in, This represents the angular rate of the gyroscope in the photoelectric stabilization platform.

[0017] The disturbance observer performs inverse calculations on the actual output of the system using the inverse model of the system. The difference between the result and the original control quantity yields the equivalent disturbance. This equivalent disturbance is then fed forward into the current loop to compensate for the total disturbance of the system in real time.

[0018] After the total disturbance of the system is compensated, the equivalent model of the system is: ; The gyroscope angular velocity output by the system The position state is obtained by integrating the complex field variable. (Complex domain variables), at this point the system transforms into a standard second-order linear control system: .

[0019] Step 2 specifically involves: based on the first-order integral system approximated in Step 1, constructing the corresponding position loop input through gyro integration, thereby forming an integral cascaded condition. The difference between the current actual speed and the desired speed is then used to obtain the speed state. ;Will Integrating to obtain the position state Two state variables are obtained. (Continuous quantity in the time domain).

[0020] Step 3 specifically involves designing a discrete-time optimal controller based on the cascaded second-order linear control system constructed in Steps 1 and 2. For the cascaded integrator system, the system architecture is as follows: ; , Position status, Indicates the position of the gyroscope's integral angle. Indicates the position output status. express The first derivative, In terms of speed state, To control the quantity, To limit the output of the control quantity. This is used when the system transitions from any state. Time-optimal control law to zero state ,in, and In This indicates the operation of finding the first derivative; ;right Discretization using the trapezoidal rule yields the discrete equations of the controlled object: ; in, Represents the number of discrete-time beats. This indicates the control sampling period value.

[0021] Based on the initial state Determine the control quantity at the phase plane position. For example... Figure 2 As shown, the initial state The region that reaches zero under two-step discrete control is: and A parallelogram formed by two sets of parallel lines. Construct three intersection functions to determine the boundary conditions: , , ; When the initial state The location is within a parallelogram, and the control parameters are: ; When the initial state is not located within the parallelogram, the following cases apply: when At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; in , .

[0022] Step 4 is as follows: Based on the calculation in step three, the disturbance experienced by the system is: ; Represents the sampling period of the speed. This represents the system speed feedback quantity.

[0023] The compensation amount is fed forward to the output amount to obtain the current control amount: .

[0024] Step 5 specifically involves: Obtained from step 4 As a given current closed loop, the driving voltage input to the drive module is calculated to drive the motor and shaft rotation.

[0025] Example 2 This embodiment is a further limitation of Embodiment 1.

[0026] This invention first identifies the azimuth motor and shaft load model of a certain pod system, and its open-loop transfer function. The method for determining it is as follows: I. Testing the Open-Loop Amplitude and Phase Characteristic Curve of the Controlled Object: An excitation signal is generated using a signal generator to produce a swept-frequency signal, yielding the open-loop amplitude and phase characteristic curve of the controlled object, as shown below. Figure 3 As shown.

[0027] 2. Based on the open-loop amplitude-phase characteristic curve of the controlled object obtained in step one, the open-loop transfer function is identified using the SystemIdentification toolbox in Matlab to obtain the open-loop transfer function of the controlled object. : ; The approximate treatment is as follows: ; Comparison with the open-loop amplitude-frequency curve of the test, for example Figure 4 As shown, the two are not significantly different.

[0028] The speed state is obtained by subtracting the current actual speed from the desired speed. ;Will Integrating to obtain the position state Two state variables are obtained. .

[0029] The system architecture is as follows: ; , Position status, In terms of speed state, To control the quantity, The actual value for the output limit is 5.

[0030] Discretization using the trapezoidal rule yields the discrete equations of the controlled object: ; For discrete time steps, This indicates that the actual value of the control sampling period is 0.01.

[0031] When the initial state is located within the parallelogram, meaning it can be reached in two steps, the control quantity is set as follows: ; When the initial state is not located within the parallelogram, the following cases apply: when At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; when and At that time, the control quantity is taken as: ; in , .

[0032] The disturbances experienced by the computing system are: ; Take 0.001, Take 0.1348.

[0033] The compensation amount is fed forward to the output amount to obtain the current control amount:

[0034] As a given current closed loop, the driving voltage input to the drive module is calculated to drive the motor and shaft rotation.

Claims

1. A discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer, characterized in that, The method includes the following steps: S1. Build a current closed-loop model of the airborne optoelectronic stabilization platform, motor and shaft load model, and introduce a disturbance observer to transform it into a standard series second-order linear control system. S2. Input the error between the desired speed and the feedback speed, and the integral of the error, to determine the state variables; S3. Based on the standard series-type second-order linear control system, design a discrete-time optimal controller: determine the boundary curve of the phase plane and the linear change region of the control quantity, determine the phase trajectory returning to the zero state for different initial phase points, and obtain the corresponding control quantity according to different regions during the motion process; S4. Input the control quantity and feedback speed obtained in step S3 into the disturbance observer to calculate the current control quantity. S5. Input the current control quantity into the current closed loop, calculate the drive voltage, and input it into the drive module to drive the motor and shaft rotation.

2. The discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer according to claim 1, characterized in that, In the current closed-loop, motor, and shaft load model of the airborne optoelectronic stabilization platform, the transfer function between the current setpoint and the gyro angular rate feedback is: ,in, Denotes the complex variable in the Laplace transform. Represents the open-loop transfer function. This represents the constant term in the simplified model.

3. The discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer according to claim 2, characterized in that, After introducing a disturbance observer to transform it into a standard series-type second-order linear control system, the current control quantity... and total disturbance Under the influence of the input, the system output is: ;in, This represents the angular rate of the gyroscope in the photoelectric stabilization platform.

4. The discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer according to claim 3, characterized in that, The state variable is ,in, This represents the error between the expected speed and the feedback speed. Indicates will The position state is obtained by integration.

5. The discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer according to claim 4, characterized in that, The boundary curves of the phase plane and the linear variation region of the control quantity are determined as follows: Based on the architecture of a standard series-type second-order linear control system Obtain the ability to make the system transition from any state Time-optimal control law to zero state ,in, and In This indicates the operation of finding the first derivative; ； express Output limiting, for Discretization using the trapezoidal rule yields the discrete equations of the controlled object: ； in, Represents the number of discrete-time beats. This indicates the control sampling period value; The boundary curve of the phase plane and the linear variation region of the control quantity are determined as follows. and A parallelogram formed by two sets of parallel lines, wherein... This indicates the control sampling period value.

6. The discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer according to claim 5, characterized in that, For different initial phase points, the phase trajectory returning to the zero state is determined, and the corresponding control quantities are obtained according to different regions during the motion process, specifically as follows: Construct three functions to determine the intersection of boundary conditions: , , ; When the initial state The location is within a parallelogram, and the control parameters are: ； When the initial state is not located within the parallelogram, the following cases apply: when At that time, the control quantity is taken as: ； when and At that time, the control quantity is taken as: ； when and At that time, the control quantity is taken as: ； when and At that time, the control quantity is taken as: ； when and At that time, the control quantity is taken as: ； in , .

7. The discrete-time control method for an optoelectronic stabilization platform based on a disturbance observer according to claim 6, characterized in that, The disturbance experienced by the computational system in the disturbance observer for: ;in, Represents the corresponding discrete-time number of beats System feedback speed at that time The speed sampling period is used to feed the compensation amount forward to the output to obtain the current control amount. , .

8. A discrete-time control device for an optoelectronic stabilization platform based on a disturbance observer, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-7.

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