Photoelectric turntable servo tracking control method, storage medium and system

Abstract

The invention discloses a photoelectric turntable servo tracking control method, a storage medium and a system, and relates to the technical field of servo control, and the method comprises the steps: receiving target deviation value information; caching the actual position information for a corresponding time length based on the target calculation and the transmission delay time length, and using the actual position before transmission and calculation when processing the target deviation information, so that the target deviation is consistent with the actual position information in time, and the target position is obtained; according to the target deviation and the actual position information, a predicted speed is calculated and output through feedforward control, the obtained target position is input into a position ring to obtain speed output, and the speed output and the predicted speed input are combined to a speed ring. According to the established data caching and feed-forward compensation model, the servo system compensates system predictive interference in advance, carrier motion and other interference factor influences are effectively restrained, response delay is reduced, the system tracking precision is improved, the dynamic response speed is increased, and real-time smooth tracking control is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of servo control, and in particular to a photoelectric turntable servo tracking control method, storage medium and system integrating feedforward compensation and array buffer mechanism. Background Art

[0002] The optoelectronic tracking system is a high-precision target tracking device that integrates optics, mechanics, electrical, control, and signal processing. Its main task is to capture and track the target. Servo jitter and tracking lag are common phenomena and difficulties in the servo turntable during the system tracking process. Tracking lag is often caused by dynamic tracking errors, mainly including the lag of target deviation information.

[0003] When the system is in the tracking working state, the general process of its servo control tracking system is as follows: first, the infrared payload generates an image, and then the target deviation between the tracked target and the visual axis is obtained through processing by the image tracking board, and the target deviation information is transmitted to the optoelectronic platform servo system. The servo motor can align the visual axis of the infrared payload with the target according to the target deviation information to achieve target tracking. In the optoelectronic tracking system, the target deviation delay at each sampling time is mainly determined by the thermal radiation accumulation time of the infrared payload in the process of generating the image, the calculation time of the image tracking algorithm, and the serial communication transmission time of the target deviation information. Since the infrared payload in the optoelectronic platform needs a period of time to accumulate thermal radiation in the process of generating the image, and the image tracking board also needs a period of time to calculate the target deviation information, after the target deviation information is calculated, it is transmitted to the servo control system by serial communication. Therefore, the target deviation delay lag time is an uncertain time-varying delay within a certain range. This lag will inevitably affect the stability and tracking accuracy of the servo control system, and is the main factor affecting the tracking performance of the optoelectronic platform. On the one hand, since the target deviation information received by the optoelectronic platform servo system has a large delay, the direct impact is the loss of phase margin, which leads to an increase in the overshoot of the servo control system and even oscillation of the system. At the same time, the target deviation lag will also reduce the maximum bandwidth that the position loop can achieve, which will lead to a decrease in the system tracking accuracy and affect the stability of the tracking system. Therefore, in actual engineering applications, a simple, practical, and high-precision target deviation lag compensation method is an urgent problem to be solved in the servo system tracking control.

[0004] In the photoelectric tracking system, the main methods to improve the tracking accuracy of the servo system include speed or acceleration lag compensation, introduction of integral links to form dynamic high-type control, and feedforward control. Among them, speed or acceleration lag compensation is a commonly used method, but this method has limited ability to improve tracking accuracy, and the determination of speed or acceleration compensation parameters is also relatively complicated. The method of introducing integral links to form high dynamic control is subject to the requirements of control system stability and is generally rarely used. Feedforward control uses the prediction principle to obtain the current position and speed information of the target to achieve feedforward compensation. Since this method compensates for the lag of the target deviation information, it can improve tracking accuracy without affecting the stability of the system, and has strong advantages. Such as:

[0005] (1) CN113867423A discloses a servo turntable azimuth angle tracking control method and device, which adopts a combination of target angular velocity prediction, dynamic curve planning, and feedforward differential first PD control algorithm to achieve fast and high-precision azimuth angle tracking and fast and stable high-precision complex signal tracking;

[0006] (2) Research on optoelectronic system tracking control technology based on predictive filtering ([D]. He Qiunong. University of Chinese Academy of Sciences, 2021.) Two robust predictive filtering methods that take into account both model uncertainty and measurement delay are proposed, the corresponding recursive filtering procedures are derived, and the conditions for the convergence and boundedness of the predictive filtering algorithm are given. Experiments have proved that these two robust predictive filtering methods can effectively improve the prediction accuracy of target motion state information when the target motion model exists uncertainty.

[0007] The servo turntable azimuth angle tracking control method mentioned in (1) above can effectively compensate for the target deviation lag problem. However, the servo tracking control is more important to assess the dynamic accuracy. The selected method cannot guarantee the real-time tracking, and there are also problems of system overshoot or oscillation.

[0008] The robust prediction filtering method mentioned in (2) above has made improvements in the filtering principle. Although the computational complexity is similar to that of Kalman filtering, the time delay is processed by an augmented state vector. As the time delay increases, the computational complexity of the recursive filtering program will increase sharply, making it unsuitable for practical engineering applications.

[0009] In view of this, it is necessary to provide a servo tracking control method that integrates feedforward compensation and array cache mechanism to address the shortcomings of the above method, so as to solve the defects of high model calculation complexity, low tracking accuracy and poor real-time performance in actual engineering applications, while suppressing the overshoot or oscillation problems caused by interference, improving the dynamic response speed, and realizing real-time, smooth and precise tracking control. Summary of the invention

[0010] The technical problem to be solved by the present invention is: in view of the tracking lag problem caused by the input and output time asynchronism in the servo control process of the photoelectric turntable, a feedforward compensation servo tracking control method with rapidity, real-time performance and stability is designed to solve the problems of tracking lag and low tracking accuracy in the actual tracking process, while improving the system tracking accuracy, enhancing the dynamic response speed and realizing real-time and smooth tracking control.

[0011] The purpose of the present invention is to solve the problems of servo disturbance, tracking lag and low tracking accuracy in practical applications, which are caused by the high model calculation complexity of the existing servo tracking control method, and the defects of low tracking accuracy, dynamic response delay and non-smooth tracking in practical engineering applications, thus affecting the overall tracking performance of the system target. In order to solve the problems of servo disturbance, tracking lag and low tracking accuracy in practical applications, a servo tracking control method integrating feedforward compensation and array cache mechanism is proposed. According to the established data cache and feedforward compensation model, the servo system can compensate for the system's predicted interference in advance, effectively suppress the influence of carrier motion and other interference factors, reduce response delay, improve system tracking accuracy, increase dynamic response speed, and realize real-time smooth tracking control.

[0012] The specific technical scheme of the present invention is:

[0013] A photoelectric turntable servo tracking control method, comprising:

[0014] Step 1, receiving target location information, including:

[0015] Step 1.1, read the target deviation feedback from the tracking board, and convert the target deviation in the horizontal and pitch directions in pixels into the target deviation in degrees according to the row and column resolutions of the image (row × column, pixels);

[0016] Step 1.2, filtering the obtained target deviation and caching the data according to the control cycle signal;

[0017] Step 1.3, read the angle information fed back by the encoder and cache the data;

[0018] Step 1.4, based on the signal delay, establish the correlation between the current target deviation information and the angle information fed back by the encoder before the delay signal, where the signal delay is the frame rate transmission signal delay + communication delay + uncertain delay signal delay.

[0019] Step 2, generating a feedforward control signal according to the target position information, including:

[0020] Assume that n is the control cycle number, n = 1, 2, ..., b is the weight coefficient, b = 1 / (1+T S * bandwidth); T Sis the time to transmit one frame of image, V t is the actual angular velocity.

[0021] Step 2.1: Send the target deviation information and the angle information fed back by the encoder into the position loop PID to obtain the target feedback angular velocity V f ;

[0022] Step 2.2: The target predicted angular velocity is the weighted fusion of the predicted velocity and the actual velocity in the previous control cycle. That is, the target predicted angular velocity calculation formula is V p (n) = b*V p (n-1)+(1-b)V t (n-1);

[0023] Step 2.3: Weighted fusion of the target feedback angular velocity and the target predicted angular velocity is used to obtain the final feedforward control signal. The calculation formula of the feedforward control signal V is: V = V p *Ф+V f ;

[0024] The weight ratio Φ in the above formula will be dynamically adjusted according to the deviation in step 5; in a specific embodiment, the value range of the weight ratio Φ is 1.1 to 1.4.

[0025] Step 3: Store the feedforward control signal in a preset array buffer.

[0026] Step 4, read the feedforward control signal from the array buffer and apply it to the servo drive.

[0027] Step 5: Adjust the feedforward control signal according to the deviation between the actual position and the target position.

[0028] Step 6, update the feedforward control signal in the array cache.

[0029] Furthermore, in a specific implementation, the filtering method may be a Kalman filtering method.

[0030] Furthermore, in the specific embodiment, assuming that the frame rate transmission signal delay, communication delay, and uncertain delay signal delay are all 20ms, the target deviation information at the current moment corresponds to the target deviation of the target position fed back by the encoder 60ms ago.

[0031] Furthermore, all relevant data involved in the feedforward control signal are cached in an array, and the array cache has a predetermined length for storing continuous feedforward control signals. The feedforward control signal is read from the array cache and applied to the servo drive to complete the target tracking operation.

[0032] Furthermore, the feedforward control signal is adjusted according to the deviation between the actual position and the target position, and the feedforward control signal in the array cache is updated. The updating operation is performed after each reading of the array cache.

[0033] A computer storage medium stores a computer program, which, when executed by a processor, implements the steps of the photoelectric turntable servo tracking control method of the present invention.

[0034] A photoelectric turntable servo tracking control system comprises a photoelectric turntable servo control computer and an angle encoder, and also comprises a computer storage medium described in the present invention.

[0035] The beneficial effects of the present invention are:

[0036] The method proposed in the present invention combines the advantages of array cache and feedforward compensation, can compensate for the influence of uncertain interference in the system in advance, solve the problems of tracking lag and low tracking accuracy in the actual tracking process, and effectively improve the tracking accuracy of the system while reducing response delay, solving the problem of system overshoot or oscillation, and realizing real-time smooth tracking control. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 : Servo control flow chart.

[0038] Figure 2 : A flow chart of generating a feedforward control signal in an embodiment.

[0039] Figure 3 : Feedforward control flow chart.

[0040] Figure 4 : Servo control tracking aircraft effect.

[0041] Figure 5 : Servo control tracking drone effect. DETAILED DESCRIPTION

[0042] See also Figure 1-3 , a photoelectric turntable servo tracking control method, comprising:

[0043] Step 1: Receive target location information, specifically:

[0044] Step 1, receiving target location information, including:

[0045] Step 1.1, read the target deviation feedback from the tracking board, and convert the target deviation in the horizontal and pitch directions in pixels into the target deviation in degrees according to the row and column resolutions of the image (row × column, pixels);

[0046] Step 1.2, filtering the obtained target deviation and caching the data according to the control cycle signal; in the specific implementation: the filtering method can be the Kalman filtering method.

[0047] Step 1.3, read the angle information fed back by the encoder and cache the data; in the specific implementation, since the encoder feedback position cycle is 2ms, 30 sets of encoder position data are cached;

[0048] Step 1.4, based on the signal delay, establish the correlation between the current target deviation information and the angle information fed back by the encoder before the delay signal, where the signal delay is the frame rate transmission signal delay + communication delay + uncertain delay signal delay. Assuming that the frame rate transmission signal delay, communication delay, and uncertain delay signal delay are all 20ms, the current target deviation information corresponds to the target deviation of the target position fed back by the encoder 60ms ago;

[0049] Step 2: Generate a feedforward control signal based on the target position information, specifically:

[0050] Assume that n is the control cycle number, n = 1, 2, ..., b is the weight coefficient, b = 1 / (1+T S * bandwidth); T S is the time to transmit one frame of image, V t is the actual angular velocity; in a specific embodiment, T S is 20ms, bandwidth is 60bps, b=0.45;

[0051] Step 2.1: Send the target deviation information and the angle information fed back by the encoder into the position loop PID to obtain the target feedback angular velocity V f ;

[0052] Step 2.2: The target predicted angular velocity is the weighted fusion of the predicted velocity and the actual velocity in the previous control cycle. That is, the target predicted angular velocity calculation formula is V p (n) = b*V p (n-1)+(1-b)V t (n-1);

[0053] Step 2.3: Weighted fusion of the target feedback angular velocity and the target predicted angular velocity is used to obtain the final feedforward control signal. The calculation formula of the feedforward control signal V is: V = V p *Ф+V f ;

[0054] Wherein, the weight ratio Φ will be dynamically adjusted according to the deviation in step 5; in a specific embodiment, the value range of the weight ratio Φ is 1.1 to 1.4.

[0055] Step 3, storing the feedforward control signal in a preset array buffer;

[0056] Step 4, read the feedforward control signal from the array buffer and apply it to the servo drive;

[0057] Step 5, adjusting the feedforward control signal according to the deviation between the actual position and the target position;

[0058] Step 6, update the feedforward control signal in the array cache.

[0059] The relevant data involved in the above feedforward control signal are all cached in an array, and the array cache has a predetermined length for storing continuous feedforward control signals. The feedforward control signal is read from the array cache and applied to the servo drive to complete the target tracking operation.

[0060] The feedforward control signal is adjusted according to the deviation between the actual position and the target position, and the feedforward control signal in the array cache is updated. The updating operation is performed after each reading of the array cache.

[0061] Example

[0062] See also Figure 1-5 As an embodiment, the specific steps of the present invention are:

[0063] 1. Unit conversion: The target deviation feedback from the tracking board is received in a 20ms communication cycle. The target deviation in pixels is converted into the target deviation Error in degrees according to the image. The conversion process is: if the image resolution is 640×512 pixels (horizontal×vertical), then the pitch deviation × 4÷512. The calculation and conversion of the horizontal deviation are similar. Specifically, in this embodiment, the target pitch deviation is fed back by the tracking board, and then the Error is subjected to Kalman filtering to output Error_K.

[0064] 2. Combining the frame rate transmission signal delay, communication delay, and uncertain delay signal delay, all of which are 20ms, the target deviation information received at the current moment corresponds to the actual target deviation 60ms ago. Therefore, the encoder position data 60ms ago + target deviation is required to be input into the position loop as the target position value;

[0065] 3. After the product is powered on, the 2ms timing cycle is started, and the real-time position value of the encoder is cached every 2ms. When the cached number reaches 30, the oldest value is discarded in the 2ms cycle again, and the latest value is stored. The array cache always maintains 30 sets of data. Let the first value stored be EnoderValue[0], and the last value stored be EnoderValue

[29] . EnoderValue[0] is the position value 60ms ago.

[0066] 4. Combine steps 1, 2, and 3. When the tracking instruction is turned on, input EnoderValue[0]+Error_K into the position loop;

[0067] 5. Set MoveToAngle = EnoderValue[0] + Error_K, and substitute MoveToAngle into the feedforward control function Vp(n) = b*Vp(n-1) + (1-b)Vt(n-1). The period of the feedforward control function is consistent with the period of the target deviation feedback from the tracking board, which is 20ms. The specific calculation steps are as follows:

[0068] (1) Set the target angle of the previous cycle to MoveToAngle_Last;

[0069] (2) Then Vt(n-1)=(MoveToAngle-MoveToAngle_Last) / Ts,

[0070] Ts is the calculation period equal to 0.02s, b = 1 / (1 + Ts * bandwidth), the bandwidth is 60bps, b = 0.45;

[0071] (3)Vp(n)=0.45*Vp(n-1)+0.55*[(MoveToAngle-MoveToAngle_Last) / 0.002];

[0072] (4) Vp(n-1) = Vp(n);

[0073] (5) When the next cycle comes, execute (3) to (4) repeatedly;

[0074] 6. Get the feedforward prediction value Vp and the position loop output value Vf, substitute them into the formula V=Vp*Ф+Vf as the speed loop input, and take Ф as 1.2.

[0075] 7. The weight value of Ф can be adjusted appropriately according to actual conditions;

[0076] 8. Complete the target tracking operation.

Claims

1. A photoelectric turntable servo tracking control method, characterized in that: The following steps are involved: Step 1, receiving target location information; Step 2, generating a feedforward control signal according to the target position information, including: Step 2.1: Send the target deviation information and the angle information fed back by the encoder into the position loop PID to obtain the target feedback angular velocity V f ; Step 2.2, target predicted angular velocity V p (n) is: V p (n) = b*V p (n-1)+(1-b)V t (n-1) In the formula, n is the control cycle number, b is the weight coefficient, V t is the actual angular velocity; Step 2.3, the target feedback angular velocity V is: V = V p *Ф+V f In the formula, Ф is the weight ratio; Step 3, storing the feedforward control signal in a preset array buffer; Step 4, read the feedforward control signal from the array buffer and use it to drive the servo motor to track the target position; Step 5, adjusting the feedforward control signal according to the deviation between the actual position and the target position; Step 6, update the feedforward control signal in the array cache.

2. The method according to claim 1, characterized in that In step 2: b=1 / (1+T S × bandwidth) Where, T S The time to transmit one frame of image.

3. The method according to claim 1, characterized in that In step 2: The weight ratio Φ is dynamically adjusted according to the deviation in step 5.

4. The method according to claim 3, characterized in that In step 3: The array in the array buffer has a predetermined length and is used for storing continuous feedforward control signals.

5. The method according to claim 1, characterized in that: In step 5: The deviation adjustment is achieved by comparing the difference between the actual position and the target position.

6. The method according to claim 1, characterized in that In step 6: Update operations are performed after each read of the array buffer.

7. The method according to any one of claims 1 to 6, characterized in that: The value range of Φ is 1.1 to 1.

4.

8. The method according to any one of claims 1 to 6, characterized in that: Step 1 also includes: Step 1.1, read the target deviation feedback from the tracking board, and convert the target deviation in the horizontal and pitch directions in pixels into the target deviation in degrees according to the row and column resolution of the image; Step 1.2, filtering the obtained target deviation and caching the data according to the control cycle signal; Step 1.3, read the angle information fed back by the encoder and cache the data; Step 1.4, based on the signal delay, establish the current target deviation information and the angle information fed back by the encoder before the delay signal, where the signal delay is the frame rate transmission signal delay + communication delay + uncertain delay.

9. A computer storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the photoelectric turntable servo tracking control method as described in any one of claims 1 to 8 are implemented.

10. A photoelectric turntable servo tracking control system, comprising a photoelectric turntable servo control computer and an angle encoder, characterized in that: Also included is a computer storage medium as claimed in claim 9.

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