A high-precision laser double-loop tracking system and control method suitable for long-distance and moving targets

Abstract

The application discloses a high-precision laser double-loop tracking system and control method suitable for long-distance and moving targets, and relates to the field of laser tracking of moving targets. The high-precision laser double-loop tracking system and control method suitable for long-distance and moving targets are adopted, the coarse and fine composite shaft double-loop tracking control system of the energy-charged target is effectively combined with the off-target amount time lag compensation system of the energy-charged target, and the problem of high-precision laser tracking of long-distance (more than 100 meters) and moving targets is effectively solved. The problem of low energy transmission efficiency caused by low tracking precision in the unmanned aerial vehicle laser wireless energy transmission system is solved, and high precision, high real-time performance and high anti-interference performance of the unmanned aerial vehicle laser energy transmission are realized.

Description

Technical Field

[0001] This invention relates to the field of laser tracking of moving targets, specifically to a high-precision laser dual-ring tracking system and control method suitable for long-distance, moving targets. Background Technology

[0002] With the rapid development of control technology, computer technology, communication technology and new materials, drones have been widely used in military and civilian fields. They are characterized by flexibility, efficiency and safety, and play an important role in battlefield attack, search and rescue, real-time monitoring and reconnaissance. Judging from the current development status and application needs of drones, the development of high-energy laser technology and artificial intelligence has provided an effective solution for the continuous flight of drones. This means that optical drones are an important development direction, which puts forward higher requirements for the energy supply of drones.

[0003] To achieve a stable and continuous supply of laser energy, a laser wireless power transfer system for unmanned aerial vehicles (UAVs) relies on the Acquisition, Tracking, and Pointing (ATP) subsystem. The ATP subsystem is a crucial component of the UAV laser wireless power transfer system; its primary task is to ensure that the laser beam emitted by the laser transmitter is precisely pointed towards the photovoltaic array receiver, achieving real-time tracking and thus establishing a stable and reliable laser power supply link.

[0004] However, in practical applications, the complex movement trajectory of UAVs, the long laser transmission distance, the signal transmission delay, and the platform vibration at the laser transmitter all easily affect tracking accuracy, leading to lower energy transfer efficiency. Therefore, to improve the charging efficiency of UAV laser wireless energy transfer systems and achieve continuous flight of photodynamic UAVs, a high-precision laser dual-ring tracking system and control method suitable for long-distance, moving targets is proposed. Summary of the Invention

[0005] This invention provides a high-precision laser dual-ring tracking system and control method suitable for long-distance, moving targets, which solves the problem of low energy transmission efficiency caused by low tracking accuracy in UAV laser wireless energy transmission systems, and achieves high precision, high real-time performance and high anti-interference performance in UAV laser energy transmission.

[0006] The technical solution adopted in this invention is a high-precision laser dual-loop tracking system suitable for long-range, moving targets. This system includes: a coarse and fine composite axis dual-closed-loop tracking control system for charged targets, and a miss-delay compensation system for charged targets. The coarse and fine composite axis dual-closed-loop tracking control system consists of a coarse tracking system and a fine tracking system. The coarse tracking system comprises a two-dimensional gimbal, a coarse tracking detector, and a coarse tracking controller. The coarse tracking controller controls the rotation of the two-dimensional gimbal based on the detection results of the coarse tracking detector. The fine tracking system consists of a fast reflector, a fine tracking detector, a fine tracking controller, and a voice coil motor. The fine tracking controller controls the fast reflector and the voice coil motor based on the detection results of the fine tracking detector. The miss-delay compensation system for charged targets, based on the coarse and fine composite axis dual-closed-loop tracking control system, incorporates a high-precision predictive filtering algorithm to form a feedforward compensation control, thereby improving tracking accuracy and reducing the impact of signal transmission delay on the system.

[0007] A high-precision laser dual-loop control method suitable for long-distance, moving targets, the method comprising:

[0008] Step 1: Initial positioning;

[0009] Step 2: Coarse tracking loop tracking;

[0010] Step 3: Fine-track loop tracking;

[0011] Step 4: Time Delay Compensation;

[0012] The specific method for preliminary positioning in step 1 is as follows:

[0013] The spatial coordinates of the charging target are obtained by using the Beidou satellite navigation system installed on the charging target. Combined with the position information of the laser energy transmitter on the ground, the deviations of the target's line of sight and the transmitter's line of sight on the azimuth and pitch axes are calculated. The turntable is rotated to make the transmitter's line of sight point to the target.

[0014] The specific method for coarse tracking loop tracking in step 2 is as follows:

[0015] The coarse tracking loop tracking process includes: a coarse tracking detector, a coarse tracking controller, and a coarse tracking controlled object. The coarse tracking detector consists of a CCD camera and corner reflectors on a photovoltaic array. The coarse tracking controlled object is a two-dimensional gimbal that can rotate in the pitch and horizontal directions. Its working steps are as follows: the laser energy emitter emits a beacon laser beam, which performs a "matrix spiral scan" on the initially located area. When the beacon laser scans the corner reflector, it will cause the incident light to be reflected parallel to the incident direction. Then, the CCD detector at the laser energy emitter captures the image position of the reflected beacon spot. The relative spatial position error between the charged target and the laser emitter is then calculated. Finally, the two-dimensional gimbal at the laser emitter is rotated so that the reflected beacon spot is located at the center of the CCD image.

[0016] The specific method for step 3, fine-tracking loop tracking, is as follows:

[0017] The fine tracking loop consists of a fine tracking detector, a fine tracking controller, and a fine tracking controlled object. The fine tracking detector includes a photovoltaic array with a TCT structure and a current symmetry information detection circuit composed of four sets of photoresistors. The four sets of photoresistors form a cross shape, with each set located on one side of the cross shape and within the gaps between the photovoltaic units in the photovoltaic array. The fine tracking controlled object consists of a fast reflector capable of tilting in both the pitch and horizontal directions and a voice coil motor. The voice coil motor drives the fast reflector to tilt in both the pitch and horizontal directions. The specific working steps are as follows: After the coarse tracking loop rapidly tracks the charging target, the laser energy emitter can quickly point to the photovoltaic array energy receiver. At this point, the laser is emitted, and it illuminates the photovoltaic array. However, the laser beam... The laser spot center could not be precisely aligned with the center of the photovoltaic array, resulting in reduced energy transfer efficiency. At this time, the position of the laser spot was detected by a current symmetry information detection circuit composed of four sets of photoresistors placed on the photovoltaic array to see if it was tangent to the photovoltaic array. When the laser spot was exactly tangent to the photovoltaic array receiver, the four photoresistors received the same laser irradiation and generated the same current. When there was a slight deviation between the center of the laser spot and the center of the photovoltaic array receiver, the magnitude of the current generated by the upper and lower photoresistors was judged to see if the spot was deviated vertically, and the magnitude of the current generated by the left and right photoresistors was judged to see if the spot was deviated horizontally. Then, the communication module fed back to the laser transmitter to control the fine tracking actuator, and the fast reflector finely adjusted the laser beam direction to achieve alignment between the center of the laser spot and the center of the photovoltaic array receiver.

[0018] Furthermore, the coarse tracking loop in step 2 and the fine tracking loop in step 3 must form a control loop. Specifically, T1(s) and T2(s) represent the transfer functions of the coarse tracking detector and the fine tracking detector, respectively. When the signal-to-noise ratio of the tracked target is good, it is considered a delay element. C1(s) and C2(s) are the controllers of the coarse tracking system and the fine tracking system, respectively, and P1(s) and P2(s) are the controlled objects of the coarse tracking system and the fine tracking system, respectively. The coarse tracking detector detects the control result of the coarse tracking loop. The transfer function T1 of the coarse tracking detector... The coarse tracking loop (s) passes through the coarse tracking system controller C1(s) and the coarse tracking system controlled object P1(s) in sequence and returns the current target position to the coarse detector. When the coarse detector determines that the positioning of the coarse tracking loop meets the requirements, the fine tracking loop is started. The fine tracking detector detects the control result of the fine tracking loop. The transfer function T2(s) of the fine tracking detector passes through the fine tracking system controller C2(s) and the fine tracking system controlled object P2(s) in sequence and returns the current target position to the fine tracking detector. The coarse tracking loop and the fine tracking loop work together to form the composite tracking system.

[0019] The error transfer functions E1(s) of the coarse tracking loop, E2(s) of the fine tracking loop, and E3(s) of the compound axis system are obtained as follows:

[0020]

[0021] Where W1(s) represents the closed-loop transfer function of the coarse tracking loop and W2(s) represents the closed-loop transfer function of the fine tracking loop.

[0022] Furthermore, the time delay compensation method in step 4 is as follows: the miss distance of the charged target is obtained by coarse tracking detector. In order to reduce the impact of the miss distance signal transmission delay on the tracking accuracy, the gimbal corner position is artificially delayed by M cycles, and the data is fused with the miss distance to obtain the target motion state information delayed by M cycles, where M cycles is the signal transmission delay time. The target motion state information is subjected to predictive filtering to predict the motion state information of the moving target at the current moment. The predicted position of the moving target at the current moment is used as the input of the position loop controller, and the predicted speed of the moving target at the current moment is used as the feedforward input signal to form an equivalent composite control.

[0023] At this point, preliminary positioning, coarse tracking loop tracking, and fine tracking loop tracking have been completed, enabling high-precision laser dual-loop tracking of long-range, moving targets. However, in actual engineering projects, preliminary positioning, coarse tracking loop tracking, and fine tracking loop tracking require communication of position errors to form a closed-loop feedback. In particular, the coarse tracking loop involves a series of operations, such as image processing and centroid recognition, for the CCD camera to calculate the miss distance, which is much more complex than that of the fine tracking detector, causing a time lag. This will have a certain impact on tracking accuracy. Therefore, in the high-precision laser dual-loop tracking system, a time lag compensation algorithm for the miss distance of charged targets is designed. A high-precision predictive filtering algorithm is used to predict the motion information of charged targets with data fusion lag, obtain the predicted miss distance information, and transmit the position information to the position loop and feed the velocity information forward to the velocity loop, thereby reducing the impact of the miss distance time lag on tracking accuracy.

[0024] This invention employs a high-precision laser dual-loop tracking system and control method suitable for long-distance, moving targets. By effectively combining a coarse and fine composite axis dual closed-loop tracking control system for charged targets with a time delay compensation system for miss distance of charged targets, it effectively solves the problem of high-precision laser tracking of long-distance (greater than 100 meters) moving targets. Attached Figure Description

[0025] Figure 1 This is a diagram of a high-precision laser dual-ring tracking system for long-distance, moving targets, according to the present invention.

[0026] Figure 2 These are coarse and fine tracking field-of-view images of the UAV laser power transmission system.

[0027] Figure 3 This is a block diagram of the coarse and fine composite axis dual closed-loop control of the UAV laser energy transfer system.

[0028] Figure 4 This is a flowchart of the high-precision tracking process for a drone laser energy transfer system.

[0029] Figure 5 This is the schematic diagram of the coarse tracking loop control principle.

[0030] Figure 6 This is a matrix spiral scan of the charged target by a beacon laser.

[0031] Figure 7 This is the schematic diagram of the precision tracking loop control principle.

[0032] Figure 8 This is a schematic diagram of the photovoltaic array receiver design.

[0033] Figure 9 This is a diagram of the time delay compensation system for the energy target miss.

[0034] Figure 10 This is a schematic diagram of the coarse tracking loop's miss distance time delay compensation principle. Detailed Implementation

[0035] The technical solution of the present invention will be described in detail below through a specific embodiment and in conjunction with the accompanying drawings:

[0036] like Figure 1 As shown, this is a specific tracking schematic diagram of a high-precision laser dual-loop tracking system suitable for long-range, moving targets in this embodiment. It consists of a laser energy emission system, a photovoltaic array receiving system, and a high-precision tracking system. The laser energy emission system consists of an electro-optical converter, a two-dimensional gimbal, a CCD camera, a fast reflector, and a communication device; the photovoltaic array receiving system consists of an electro-optical converter, a corner reflector, a current detection device, a photodynamic drone, a storage battery, and a BeiDou satellite navigation system; the high-precision tracking system consists of a coarse and fine composite axis dual-closed-loop tracking control algorithm for charged targets and a time-delay compensation algorithm for missed targets.

[0037] like Figure 2 As shown, this is a coarse and fine tracking field of view diagram of the UAV laser tracking system. It consists of a coarse tracking field of view and a fine tracking field of view. The coarse tracking loop stabilizes the charging target at the center of the coarse tracking field of view through closed-loop tracking, and then introduces the fine tracking field of view. The fine tracking loop further eliminates the tracking residual of the coarse tracking through closed-loop tracking, and stabilizes the charging target at the center of the fine tracking field of view.

[0038] The schematic diagram of the dual-loop tracking control principle for coarse and fine tracking fields of view is shown below. Figure 3 As shown, the coarse and fine composite axis dual-loop tracking control system is divided into a coarse tracking control loop and a fine tracking control loop. In the schematic diagram of the coarse and fine tracking composite axis, T1(s) and T2(s) represent the transfer functions of the coarse tracking detector and the fine tracking detector, respectively. When the signal-to-noise ratio of the tracking target is good, they can be regarded as a delay element. C1(s) and C2(s) are the controllers of the coarse and fine tracking systems, respectively, and P1(s) and P2(s) are the controlled objects of the coarse and fine tracking systems, respectively. Simultaneously, the error transfer functions of the coarse tracking loop, the fine tracking loop, and the composite axis system are obtained as follows:

[0039]

[0040] It is evident that the error transfer function E3(s) of the coarse and fine composite axis tracking system is the product of the error transfer functions of the coarse and fine tracking loops. Therefore, it can be concluded that the error-free order of the coarse and fine composite axis system is the sum of the error-free orders of the coarse and fine tracking systems, indicating that dual-loop tracking has higher tracking accuracy.

[0041] like Figure 4As shown, the high-precision laser dual-ring tracking system and control method suitable for long-distance, moving targets mainly consists of three steps: preliminary positioning, coarse tracking loop tracking, and fine tracking loop tracking.

[0042] The initial positioning of the tracked target is completed by obtaining the spatial coordinates of the target through the BeiDou satellite navigation system installed on the target. Combined with the position information of the laser energy transmitter on the ground, the deviation of the target's line of sight from the transmitter's line of sight on the azimuth and pitch axes is calculated. The turntable is rotated to make the transmitter's line of sight point towards the target.

[0043] like Figure 5 As shown, the coarse tracking loop mainly consists of a coarse tracking detector, a coarse tracking controller, and a coarse tracking controlled object. The coarse tracking detector is composed of a CCD camera and a corner reflector mounted on the photovoltaic array on the charging target. The coarse tracking controlled object is a two-dimensional gimbal that can rotate in the pitch and horizontal directions. It mainly achieves fast tracking of the charging target over a large area and a wide field of view. Its working steps are as follows: the laser energy emitting end emits a beacon laser beam, which performs a "matrix spiral scan" on the initially located uncertain area, such as... Figure 6 As shown, when the beacon laser scans the corner reflector placed on the photovoltaic array, the incident light will be reflected parallel to the incident direction. Then, the CCD detector at the laser energy emitter is used to capture the image position of the reflected beacon spot. The relative error of the spatial position between the charging target and the laser emitter is then calculated. Finally, the two-dimensional gimbal of the laser emitter is rotated so that the reflected beacon spot is located at the center of the CCD image.

[0044] like Figure 7 As shown, the fine tracking loop mainly consists of a fine tracking detector, a fine tracking controller, and a fine tracking controlled object, such as... Figure 8As shown, the fine tracking detector consists of a photovoltaic array with a TCT structure and a current-symmetric information detection circuit composed of four sets of high-sensitivity, high-resolution photoresistors. To reduce the load on the photodynamic UAV, the laser spot is designed to be tangent to the photovoltaic array. The fine tracking control object consists of a fast-reflecting mirror that can swing in both pitch and horizontal directions and a voice coil motor. It primarily aims to further eliminate the tracking residuals present in the coarse tracking loop, thereby achieving higher tracking accuracy. Its specific working steps are as follows: After the coarse tracking loop performs rapid tracking of the charged target over a large field of view, the laser energy emitter can quickly and accurately point to the photovoltaic array energy receiver. The laser is then emitted, illuminating the photovoltaic array. However, the center of the laser spot does not precisely coincide with the center of the photovoltaic array, resulting in reduced energy transfer efficiency. At this point, the current-symmetric information detection circuit composed of four sets of high-sensitivity, high-resolution photoresistors placed on the photovoltaic array detects the position of the laser spot to see if it is tangent to the photovoltaic array. Figure 8 As shown, when the laser spot illuminates the photovoltaic array receiver and the center of the laser spot coincides with the center of the photovoltaic array receiver, the laser spot is exactly tangent to the photovoltaic array receiver. At this time, the four photoresistors receive the same laser irradiation and generate the same current, i.e., i a1 i a2 i b1 i b2 i c1 i c2 i d1 i d2 Equal, when there is a slight deviation between the center of the laser spot and the center of the photovoltaic array receiver, it can be determined by judging i a with i b The size of the light spot is determined by whether it deviates vertically. c with i d The size of the laser beam is determined by whether the laser spot deviates to the left or right. This feedback is then sent to the laser transmitter to control the fine-tracking actuator to adjust the direction of the laser beam, thereby aligning the center of the laser spot with the center of the photovoltaic array receiver and achieving higher tracking accuracy.

[0045] like Figure 9 As shown, in the coarse tracking loop and fine tracking loop, feedback of position error is required to form a dual closed-loop tracking control system. However, signal transmission has a time lag, especially in the coarse tracking loop. The CCD camera performs image processing and centroid recognition on the reflected beacon laser spot, making the calculation of the miss distance much more complex than the fine tracking detector, resulting in a time lag. This will negatively impact tracking accuracy. Therefore, as... Figure 10As shown, a high-precision predictive filtering algorithm is added to the coarse tracking loop tracking system to predict the motion information of the charged target with data fusion lag, and obtain the predicted miss amount information. The position information is then passed to the position loop, and the velocity information is fed forward to the velocity loop, thereby reducing the impact of the miss amount lag on the tracking accuracy.

[0046] In summary, this invention, through the effective combination of a coarse and fine composite axis dual-closed-loop tracking control system for an energized target and a time delay compensation system for the miss distance of an energized target, has invented a high-precision laser dual-loop tracking system and control method suitable for long-distance, moving targets, providing a good solution to the problem of high-precision laser tracking of long-distance (greater than 100 meters) moving targets.

Claims

1. A high-precision laser dual-ring tracking system suitable for long-range, moving targets, the system comprising: This invention relates to a coarse and fine composite axis dual-closed-loop tracking control system for an energy-charging target, and a miss-delay compensation system for the energy-charging target. The coarse and fine composite axis dual-closed-loop tracking control system consists of a coarse tracking system and a fine tracking system. The coarse tracking system comprises a two-dimensional gimbal, a coarse tracking detector, and a coarse tracking controller. The coarse tracking controller controls the rotation of the two-dimensional gimbal based on the detection results of the coarse tracking detector. The fine tracking system comprises a fast reflector, a fine tracking detector, a fine tracking controller, and a voice coil motor. The fine tracking controller controls the fast reflector and the voice coil motor based on the detection results of the fine tracking detector. The miss-delay compensation system for the energy-charging target, based on the coarse and fine composite axis dual-closed-loop tracking control system, incorporates a high-precision predictive filtering algorithm to form a feedforward compensation control, thereby improving tracking accuracy and reducing the impact of signal transmission delay on the system. The control method of the high-precision laser dual-ring tracking system includes: Step 1: Initial positioning; Step 2: Coarse tracking loop tracking; Step 3: Fine-track loop tracking; Step 4: Time Delay Compensation; The specific method for preliminary positioning in step 1 is as follows: The spatial coordinates of the charging target are obtained by using the Beidou satellite navigation system installed on the charging target. Combined with the position information of the laser energy transmitter on the ground, the deviations of the target's line of sight and the transmitter's line of sight on the azimuth and pitch axes are calculated. The turntable is rotated to make the transmitter's line of sight point to the target. The specific method for coarse tracking loop tracking in step 2 is as follows: The coarse tracking loop tracking process includes: a coarse tracking detector, a coarse tracking controller, and a coarse tracking controlled object. The coarse tracking detector consists of a CCD camera and a corner reflector on the photovoltaic cell array. The coarse tracking controlled object is a two-dimensional gimbal that can rotate in the pitch and horizontal directions. Its working steps are as follows: the laser energy emitter emits a beacon laser beam, which performs a "matrix spiral scan" on the initially located area. When the beacon laser scans the corner reflector, it will cause the incident light to be reflected parallel to the incident direction. Then, the CCD detector of the laser energy emitter is used to capture the image position of the reflected beacon spot. The relative spatial position error between the charged target and the laser emitter is then calculated. Finally, the two-dimensional gimbal of the laser emitter is rotated so that the reflected beacon spot is located at the center of the CCD image.

2. The high-precision laser dual-ring tracking system for long-distance, moving targets as described in claim 1, characterized in that, The specific method for step 3, fine-tracking loop tracking, is as follows: The fine tracking loop consists of a fine tracking detector, a fine tracking controller, and a fine tracking controlled object. The fine tracking detector includes a photovoltaic array with a TCT structure and a current symmetry information detection circuit composed of four sets of photoresistors. The four sets of photoresistors form a cross shape, with each set located on one side of the cross shape and within the gaps between the photovoltaic units in the photovoltaic array. The fine tracking controlled object consists of a fast reflector capable of tilting in both the pitch and horizontal directions and a voice coil motor. The voice coil motor drives the fast reflector to tilt in both the pitch and horizontal directions. The specific working steps are as follows: After the coarse tracking loop rapidly tracks the charging target, the laser energy emitter can quickly point to the photovoltaic array energy receiver. At this point, the laser is emitted, and it can illuminate the photovoltaic array. However, at this time, the laser beam... The laser spot center could not be precisely aligned with the center of the photovoltaic array, resulting in reduced energy transfer efficiency. At this time, the position of the laser spot was detected by a current symmetry information detection circuit composed of four sets of photoresistors placed on the photovoltaic array to see if it was tangent to the photovoltaic array. When the laser spot was exactly tangent to the photovoltaic array receiver, the four photoresistors received the same laser irradiation and generated the same current. When there was a slight deviation between the center of the laser spot and the center of the photovoltaic array receiver, the magnitude of the current generated by the upper and lower photoresistors was judged to see if the spot was deviated vertically, and the magnitude of the current generated by the left and right photoresistors was judged to see if the spot was deviated horizontally. Then, the communication module fed back to the laser transmitter to control the fine tracking actuator, and the fast reflector finely adjusted the laser beam direction to achieve alignment between the center of the laser spot and the center of the photovoltaic array receiver.

3. The high-precision laser dual-ring tracking system for long-distance, moving targets as described in claim 1, characterized in that, The coarse tracking loop in step 2 and the fine tracking loop in step 3 must form a control loop; the specific method is as follows: using and Let represent the transfer functions of the coarse and fine tracking detectors, respectively. When the signal-to-noise ratio of the tracked target is good, they are considered as a delay element. and The controllers for the coarse tracking system and the fine tracking system are respectively. and These are the control objects of the coarse tracking system and the fine tracking system, respectively; the coarse tracking detector detects the control result of the coarse tracking loop, and the transfer function of the coarse tracking detector is... Passing sequentially through the coarse tracking system controller Coarse tracking system control object Then the current target position is returned to the coarse detector. When the coarse detector confirms that the coarse tracking loop positioning meets the requirements, the fine tracking loop is started. The fine tracking detector detects the control result of the fine tracking loop, and the transfer function of the fine tracking detector. The system sequentially passes through the controller of the precision tracking system. Controlled objects of precision tracking systems The current target position is then returned to the fine tracking detector. The coarse tracking loop and the fine tracking loop work together in the composite tracking system. Obtain the error transfer function of the coarse tracking loop. Error transfer function of the fine tracking loop and the error transfer function of the composite shaft system They are respectively: ； ； ； in, This represents the closed-loop transfer function of the coarse tracking loop. This represents the closed-loop transfer function of the fine tracking loop.

4. The high-precision laser dual-ring tracking system for long-distance, moving targets as described in claim 1, characterized in that, The time delay compensation method in step 4 is as follows: the miss distance of the charged target is obtained by coarse tracking detector. In order to reduce the impact of the miss distance signal transmission delay on the tracking accuracy, the gimbal corner position is artificially delayed by M cycles, and the data is fused with the miss distance to obtain the target motion state information delayed by M cycles, where M cycles is the signal transmission delay time. The target motion state information is then subjected to predictive filtering to predict the motion state information of the moving target at the current moment. The predicted position of the moving target at the current moment is used as the input of the position loop controller, and the predicted speed of the moving target at the current moment is used as the feedforward input signal to form an equivalent composite control.

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