Hotspot target tracking method and device based on load detection and star sensor resetting

Abstract

The invention discloses a hotspot target tracking method and device based on load detection and star sensor resetting, and belongs to the field of spacecraft attitude control. The method comprises the following steps: estimating longitude, latitude and elevation information of a target according to a time scale of load target detection information and historical load visual axis ground pointing point information; according to the maximum attitude maneuverability of the system and a five-order polynomial guide model, the fastest moment of target recapture is determined by taking time as an iteration quantity, and the target attitude in the target recapture process is autonomously planned and closed-loop control is carried out; after the target is captured again, the control system performs closed-loop control according to load real-time detection information to ensure that the target is located in the center of a load view field, and the load performs continuous imaging; after tracking imaging is finished, a guiding process of returning to scanning imaging is autonomously planned; in the whole process, the current attitude is automatically reset according to a double-vector attitude determination result of the high-precision star sensor by taking the angular velocity as a constraint, so that the pointing precision is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of spacecraft attitude control, and in particular to a hotspot target tracking method and device based on on-board payload detection and star sensitivity resetting. Background Art

[0002] High-performance remote sensing satellites generally have requirements for high spatial resolution imaging, dense imaging of hot spots, and continuous tracking and imaging of curved targets. Therefore, the satellites are required to have strong attitude agility, ultra-high pointing accuracy, and ultra-high stability, and have the potential for continuous target tracking and imaging in terms of hardware configuration.

[0003] Traditional high-performance remote sensing satellites are only the execution end, and they do not realize automatic detection of hotspot targets and tracking imaging on the satellite. Most of the imaging is done by manually controlling the satellite attitude according to the location of the hotspot target on the ground, and the task closed-loop link is long. For hotspot targets with a certain moving speed, the long task link may also lead to the loss of the target when imaging again.

[0004] With the application of intelligent algorithms, the satellite can automatically detect sensitive targets in the imaging area. If the satellite automatically tracks the target and continuously images it, it can greatly improve the user's intelligence acquisition capabilities, but there is no mature solution yet. At the same time, the movement speed of ground targets is relatively small compared to satellites, and satellites need to be in a high angular velocity state. During the autonomous tracking of hotspot targets, if the existing gyro continuous integration attitude maneuvering strategy is directly used, the attitude deviation will gradually accumulate, which will lead to a gradual deterioration of pointing accuracy.

[0005] Based on this, there is an urgent need to provide a hotspot target tracking method and device based on payload detection and star sensitivity resetting. Summary of the invention

[0006] The embodiment of the present invention provides a method and device for tracking hotspot targets based on payload detection and star sensitivity reset. The control system can autonomously switch to the target staring imaging process as soon as possible and establish the required attitude according to the system's maximum attitude maneuverability based on the hotspot target information extracted by the onboard payload during scanning imaging, so as to achieve continuous imaging of the payload for the target, and can autonomously return to the scanning imaging state after the tracking imaging is completed.

[0007] In the first aspect, a hotspot target tracking method based on payload detection and star sensitivity reset is provided, comprising:

[0008] 100, when the payload finds a target in the scanning imaging state, the control system estimates the longitude, latitude and elevation of the target based on the target measurement and time scale information output by the payload and the longitude, latitude and elevation information of the ground pointing point of the payload's visual axis at several moments that are pre-cached; wherein the payload includes a camera and an image processing unit for extracting target measurement information; the target measurement information includes the time scale, the rolling angle deviation and the pitch angle deviation of the target center from the payload's visual axis;

[0009] 102, based on the target latitude, longitude and elevation information determined in step 100, the roll angle deviation and pitch angle deviation output by the payload, according to the system maximum attitude maneuverability and the fifth-order polynomial guidance model loop iteration, determine the fastest time for target recapture, autonomously plan the target attitude of the target recapture process and perform closed-loop control, and establish the attitude required for payload target recapture;

[0010] 104, after the target is recaptured, the attitude angle error and attitude angular velocity error for control are determined based on the target measurement information stably output by the payload after recapture, and a relative attitude closed-loop control is performed to ensure that the target is located at the center of the payload field of view, while the payload performs tracking imaging;

[0011] 106, after the tracking imaging is completed, the target posture of the whole process of returning to the scanning imaging state is autonomously planned according to the system's maximum posture maneuverability and the fifth-order polynomial guidance model, and closed-loop control is performed to re-establish the posture required for the scanning imaging state in step 100;

[0012] 108. In steps 100 to 106, when the satellite inertial angular velocity is less than a threshold value, the angular velocity information is used to perform time compensation on the dual-vector attitude quaternion of the star sensor, and the inertial attitude of the satellite is reset.

[0013] In a second aspect, a hotspot target tracking device based on load detection and star sensitivity reset is provided, which is used to implement the steps described in the embodiments of this specification, including:

[0014] An estimation unit is used to estimate the longitude, latitude and elevation of the target when the payload finds the target in the scanning imaging state, based on the target measurement and time scale information output by the payload, and based on the longitude, latitude and elevation information of the ground pointing point of the payload's visual axis at several moments pre-cached; wherein the payload includes a camera and an image processing unit for extracting target measurement information; the target measurement information includes the time scale, the rolling angle deviation and the pitch angle deviation of the target center from the payload's visual axis;

[0015] The recapture unit is used to use the target latitude, longitude and elevation information determined by the estimation unit, the roll angle deviation and pitch angle deviation output by the payload, and the maximum attitude maneuverability of the system and the fifth-order polynomial guidance model loop iteration to determine the fastest time for target recapture, autonomously plan the target attitude of the target recapture process and perform closed-loop control to establish the attitude required for payload target recapture;

[0016] The tracking unit is used to determine the attitude angle error and attitude angular velocity error for control based on the target measurement information stably output by the payload after recapture after the payload completes target recapture, and perform relative attitude closed-loop control to ensure that the target is located at the center of the payload's field of view, while the payload performs tracking imaging;

[0017] The return unit is used to autonomously plan the target posture of the whole process of returning to the scanning imaging state according to the system's maximum posture maneuverability and the fifth-order polynomial guidance model after the payload tracking imaging is completed, and to perform closed-loop control to re-establish the posture required for the scanning imaging state in the estimation unit;

[0018] The reset unit is used to use the angular velocity information to perform time compensation on the dual-vector attitude quaternion of the star sensor and reset the inertial attitude of the satellite when the inertial angular velocity of the satellite is less than a threshold value.

[0019] In a third aspect, a computer device is provided, comprising a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the steps of the above-mentioned method.

[0020] In a fourth aspect, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned method are implemented.

[0021] The present invention provides a hotspot target tracking method and device based on payload detection and star sensitivity resetting. Based on this, the control system and the payload system work together autonomously to achieve autonomous tracking and imaging of hotspot targets on orbit, breaking the status quo of traditional remote sensing satellites being only the execution end and causing long task closed-loop links, and can greatly improve the target information acquisition capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1It is a flow chart of a hotspot target tracking method based on load detection and star sensitivity reset provided by an embodiment of the present invention;

[0024] Figure 2 It is a structural diagram of a hotspot target tracking device based on load detection and star sensitivity reset provided by an embodiment of the present invention;

[0025] Figure 3 It is a hardware architecture diagram of a computer device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] The idea of ​​the present invention is to utilize the target detection information output by the on-board image processing unit, with the satellite's maximum attitude maneuverability and attitude control torque smoothing as constraints, determine the fastest time for target recapture according to the time loop iteration method, autonomously plan the target attitude of the target recapture process and switch to the target gaze process. The control system and the payload system collaborate autonomously to achieve autonomous tracking and imaging of hotspot targets on orbit. After the payload tracking imaging is completed, the attitude of the process of returning to the scanning imaging state is autonomously planned. At the same time, during the entire process, the angular velocity information is used to compensate the dual-vector attitude quaternion of the star sensor for time, and the inertial attitude of the satellite is reset at an appropriate time to solve the problem of continuous accumulation of errors caused by continuous gyro integration and ensure pointing accuracy.

[0028] The specific implementation of the above concept is described below.

[0029] Please refer to Figure 1 , a hotspot target tracking method based on payload detection and star sensitivity reset provided by an embodiment of the present invention is applied to an onboard control system, and the method includes:

[0030] Step 100, when the payload finds a target in the scanning imaging state, the control system estimates the longitude, latitude and elevation of the target based on the target measurement and time mark information output by the payload and the longitude, latitude and elevation information of the ground pointing point of the payload line of sight at several moments pre-cached;

[0031] Step 102, based on the target latitude, longitude and elevation information determined in step 100, the roll angle deviation and pitch angle deviation output by the payload, according to the system's maximum attitude maneuverability and the fifth-order polynomial guidance model loop iteration, determine the fastest time for target recapture, autonomously plan the target attitude of the target recapture process and perform closed-loop control, and establish the attitude required for payload target recapture;

[0032] Step 104, after the target is recaptured, the attitude angle error and attitude angular velocity error for control are determined based on the target measurement information stably output by the payload after recapture, and relative attitude closed-loop control is performed to ensure that the target is located at the center of the payload field of view, while the payload performs tracking imaging;

[0033] Step 106, after the tracking imaging is completed, the target posture of the whole process of returning to the scanning imaging state is autonomously planned according to the system's maximum posture maneuverability and the fifth-order polynomial guidance model, and closed-loop control is performed to re-establish the posture required for the scanning imaging state in step 100;

[0034] Step 108, in steps 100 to 106, when the satellite inertial angular velocity is less than the threshold, the angular velocity information is used to perform time compensation on the dual-vector attitude quaternion of the star sensor, and the inertial attitude of the satellite is reset.

[0035] In an embodiment of the present invention, it is necessary to ensure that the roll axis and pitch axis of the onboard control system are consistent with the roll axis and pitch axis definitions of the payload output information. If there is any inconsistency, the conversion must be completed through the installation array before outputting to the control system or before the control system applies this method.

[0036] Described below Figure 1 How the various steps are performed.

[0037] Regarding step 100, the specific implementation example is as follows:

[0038] First, according to the delay time from the exposure of the payload detection information to the arrival of the control system, the cache queue depth of the control system computer's own information is set to no less than three times the delay time. When scanning imaging begins, the cache queue is automatically maintained by pushing in new data and deleting the oldest data. The self-information includes: the longitude, latitude, elevation and corresponding time scale information of the payload's visual axis ground pointing point.

[0039] Secondly, the control system obtains the target measurement information output by the payload, and based on the cached latitude, longitude and elevation information of the ground pointing point of the payload sight axis at several moments, uses the Newton interpolation method to obtain the latitude, longitude and elevation of the ground pointing point of the payload sight axis at the time of target detection, and uses it as the estimated latitude, longitude and elevation of the target. The target measurement information includes the time scale t0, the roll angle deviation Δφ and the pitch angle deviation Δθ of the target center from the payload sight axis.

[0040] For example, assuming that the delay time for the load detection information to reach the control system is 2s, assuming that the load scans the target at 3 o'clock (i.e., the target measurement time scale t0), and the target measurement information at 3:02 seconds is transmitted to the control system, the cache queue of the control system at this time includes at least the latitude, longitude and elevation information of the load sight axis ground pointing point from 2:59:56 to 3:02 seconds. It can be seen that the latitude, longitude and elevation information of the load sight axis ground pointing point at historical moments that are not less than three times the delay time can be cached to ensure that the target measurement time scale is within the corresponding time range of the cache queue. Then, when there is no latitude, longitude and elevation information of the load sight axis ground pointing point at the corresponding time of the target measurement in the cache queue, the Newton interpolation method can be used to estimate the latitude, longitude and elevation information of the load sight axis ground pointing point at that moment. In view of the small field of view of the load, the latitude, longitude and elevation information of the load sight axis ground pointing point at the target measurement time t0 is directly used as the latitude, longitude and elevation information of the target.

[0041] Regarding step 102, the specific implementation example is as follows:

[0042] S1, record the current on-board time and the attitude information of the three axes at the current time; the three axes are the roll axis, the pitch axis and the yaw axis, and the attitude information includes the attitude angle, the attitude angular velocity and the attitude angular acceleration.

[0043] The attitude angle, attitude angular velocity and attitude angular acceleration of the three axes at the current satellite time t are φ i0 , Where i = x, y, z, respectively representing the roll axis, pitch axis, and yaw axis. Continuing with the above example, the current on-board time t should be 3:02 seconds.

[0044] S2, determine the initial value of the time T from the current moment to the target recapture moment, that is, the minimum value of the switching time from the current posture to the target gaze posture. In this embodiment, the initial value of T is set to 2s.

[0045] S3, the current satellite orbit information is extrapolated for T seconds, combined with the latitude, longitude and elevation information of the target determined in step 100, and the expected attitude angle φ of the three axes at time t+T is calculated using the low-Earth orbit ground target point gaze target attitude calculation method im , expected attitude angular velocity and the expected angular acceleration

[0046] The desired attitude angle at time t+T is corrected using the roll angle deviation Δφ and pitch angle deviation Δθ output by the load. The specific method is as follows:

[0047] φ xm =φ xm +Δφ

[0048] φym =φ ym +Δθ

[0049] In the formula, φ xm and φ ym They are respectively the x-axis attitude angle and the y-axis attitude angle in the recapture attitude at time t+T.

[0050] S4, using the fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the recapture attitude information at the moment t+T, determine the fifth-order polynomial coefficients of the guidance process required to establish the tracking imaging attitude and the satellite attitude at each moment.

[0051] According to the time T and the fifth-order polynomial model, the polynomial coefficients of the x-, y- and z-axis guidance processes are obtained as follows:

[0052]

[0053] The fifth-order polynomial is defined as t r is relative time; b ik is the k-order coefficient of the i-axis; φ i0 , are respectively the attitude angle, attitude angular velocity and attitude angular acceleration of the i-axis at the current on-board time t; φ im , and They are the expected attitude angle, expected attitude angular velocity and expected angular acceleration of the i-axis at time t+T respectively.

[0054] Next, calculate each relative time Satellite attitude at time φ ri (t r ), attitude angular velocity and attitude angular acceleration That is, the satellite attitude at each moment in the guidance process, the formula is as follows:

[0055]

[0056] S5, determining whether the satellite attitude at each moment in the guidance process satisfies the system's maximum attitude maneuverability limit.

[0057] S6, if not satisfied, increase the time T according to the set step length. If the time T does not exceed the maximum threshold, jump to step S3, otherwise abandon the current tracking imaging and maintain the scanning imaging state.

[0058] In this embodiment, if all three axes There is a moment in the moment that does not satisfy If , it is judged as not satisfied, otherwise it satisfies the maximum attitude maneuverability limit.max v is the maximum value of the Euler attitude angle allowed by the satellite, which is 60° in this embodiment; max is the maximum angular velocity allowed by the satellite, which is 3° / s in this embodiment; a max is the maximum angular acceleration allowed by the satellite, which is 2° / s in this embodiment. 2 .

[0059] In this embodiment, the step size is set to 0.5s and the T maximum threshold is set to 100s.

[0060] S7, if satisfied, the control system performs closed-loop control based on the fifth-order polynomial coefficients of the guidance process, time T and the satellite attitude at each moment, and establishes the required attitude for payload target recapture at time t+T.

[0061] In summary, at time t+T, the payload will complete the recapture of the target, and then stably output the target measurement information, that is, the target measurement time scale t0, the rolling angle deviation of the target center from the payload visual axis and pitch angle deviation Δθ.

[0062] Regarding step 104, the specific implementation example is as follows:

[0063] The control system enters the relative error control state. According to the roll angle deviation Δφ and pitch angle deviation Δθ output by the load (after t+T), the control attitude angle error and attitude angular velocity error are calculated and closed-loop controlled to control the target at the center of the load field of view. At the same time, the load performs continuous tracking imaging.

[0064] The method for determining the attitude angle error and attitude angular velocity error based on the load output is as follows:

[0065] φ bias =Δφ-φ err ,θ bias =Δθ-θ err

[0066] φ err =φ err +m·φ bias ,θ err =θ err +m·θ bias ,

[0067]

[0068] Among them, φ err ,θ err , are the attitude angle errors of the roll axis, pitch axis, and yaw axis, which are initialized to 0 when entering for the first time; φ bias and θ biasis an intermediate variable, meaning the correction introduced by load measurement information; They are the attitude angular velocity errors of the roll axis, pitch axis and yaw axis, which are initialized to 0 when entering for the first time; m and n are correction coefficients, which are 0.1 and 0.01 respectively in this embodiment.

[0069] Regarding step 106, the specific implementation example is as follows:

[0070] After the payload tracking imaging is completed, the system's maximum attitude maneuverability and the fifth-order polynomial guidance model autonomously plan to return to the target attitude of the entire scanning imaging process, and the payload continues scanning imaging.

[0071] H1, records the current onboard time and the attitude information of the three axes at the current time; the three axes are the roll axis, pitch axis and yaw axis, and the attitude information includes attitude angle, attitude angular velocity and attitude angular acceleration;

[0072] The attitude angle, attitude angular velocity and attitude angular acceleration of the three axes at the current satellite time t are Among them, i=x, y, z, respectively represent the roll axis, pitch axis, and yaw axis.

[0073] H2, determine the initial value of the time T from the current time to the moment of establishing the scanning imaging posture, that is, the minimum value of the switching time from the current posture to the scanning imaging posture. In this embodiment, the initial value of T is set to 2s.

[0074] H3, the current satellite orbit information is extrapolated for T seconds, and the target attitude calculation method of the original scanning imaging state is used to calculate the expected attitude angle φ of the three axes at time t+T im , expected attitude angular velocity and the expected angular acceleration

[0075] H4, using the fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the scanning imaging attitude at the moment t+T, determines the fifth-order polynomial coefficients of the guidance process of returning to the scanning imaging state and the satellite attitude at each moment.

[0076] According to the time T and the fifth-order polynomial model, the polynomial coefficients of the x-, y- and z-axis guidance processes are obtained as follows:

[0077]

[0078] The fifth-order polynomial is defined as t r is relative time; b ik is the k-order coefficient of the i-axis; φ i0 , are respectively the attitude angle, attitude angular velocity and attitude angular acceleration of the i-axis at the current on-board time t; φim , and They are the expected attitude angle, expected attitude angular velocity and expected angular acceleration of the i-axis at time t+T respectively.

[0079] Next, calculate each relative time Satellite attitude at time φ ri (t r ), attitude angular velocity and attitude angular acceleration That is, the satellite attitude at each moment in the guidance process, the formula is as follows:

[0080]

[0081] H5, determines whether the satellite attitude at each moment in the guidance process meets the system's maximum attitude maneuverability value limit.

[0082] H6, if not satisfied, increase the time T according to the set step length and jump to step H3.

[0083] In this embodiment, if all three axes There is a moment in the time that does not satisfy φ ri (t r )|≤χ max , It is judged as not satisfied, otherwise it satisfies the maximum attitude maneuverability limit of the system.

[0084] In this embodiment, the step size is set to 0.5s.

[0085] H7, if satisfied, the control system performs closed-loop control according to the fifth-order polynomial coefficients of the guidance process, time T and the satellite attitude at each moment, and establishes the attitude required for the original payload scanning imaging in step 100 at time t+T.

[0086] In summary, at time t+T, the payload will start scanning imaging again and detect new hotspot targets. When the target is detected, the process of step 100 will start again.

[0087] Regarding step 108, the specific implementation example is as follows:

[0088] In steps 100 to 106, when the satellite inertial angular velocity |ω t |<ω0 and the dual star sensor is valid, the attitude quaternion q is determined by using the optical axis information of the star sensor through the standard dual-vector attitude determination method s , where ω0 is the set threshold, which is 0.2° / s in this embodiment.

[0089] Then, the inertial angular velocity information is used to determine the star sensor dual vector quaternion q sTime compensation is performed. The compensation time is the delay time Δt of the optical axis measurement information of the star sensor reaching the controller, as follows:

[0090]

[0091] Δg|=norm(Δg)

[0092]

[0093] q s =M(Δg)·q s

[0094] Among them, ω is the inertial angular velocity vector information within the time range of t-Δt~t; Δg is an intermediate variable with no real meaning, Δg x , Δg y , Δg z are the x, y, and z components of Δg respectively; Ω() and M() are intermediate functions without real meaning; norm() is the modulus function; I4 is the fourth-order unit matrix.

[0095] Finally, using q s The current inertial posture is assigned a value once, and no value is assigned again within a certain time range (30 seconds in this embodiment).

[0096] Please refer to Figure 2 The embodiment of the present invention provides a hotspot target tracking device based on load detection and star sensitivity reset. As a device in a logical sense, it is used to implement the steps of any method embodiment in the specification. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. The device includes:

[0097] The estimation unit 201 is used to estimate the longitude, latitude and elevation of the target when the payload finds the target in the scanning imaging state, according to the target measurement and time scale information output by the payload, and based on the longitude, latitude and elevation information of the ground pointing point of the payload's visual axis at several moments pre-cached; wherein the payload includes a camera and an image processing unit for extracting target measurement information; the target measurement information includes the time scale, the rolling angle deviation and the pitch angle deviation of the target center from the payload's visual axis;

[0098] The recapture unit 202 is used to use the target latitude, longitude and elevation information determined by the estimation unit, the roll angle deviation and pitch angle deviation output by the payload, and the maximum attitude maneuverability of the system and the fifth-order polynomial guidance model loop iteration to determine the fastest time for target recapture, autonomously plan the target attitude of the target recapture process and perform closed-loop control to establish the attitude required for payload target recapture;

[0099] The tracking unit 203 is used to determine the attitude angle error and attitude angular velocity error for control based on the target measurement information stably output by the payload after recapture after the payload completes target recapture, and perform relative attitude closed-loop control to ensure that the target is located at the center of the payload field of view, while the payload performs tracking imaging;

[0100] The return unit 204 is used to autonomously plan the target attitude of the whole process of returning to the scanning imaging state according to the maximum attitude maneuverability of the system and the fifth-order polynomial guidance model after the payload tracking imaging is completed, and to perform closed-loop control to re-establish the attitude required for the scanning imaging state in the estimation unit;

[0101] The reset unit 205 is used to perform time compensation on the dual-vector attitude quaternion of the star sensor using the angular velocity information and reset the inertial attitude of the satellite when the inertial angular velocity of the satellite is less than a threshold value.

[0102] In one embodiment of the present invention, the estimation unit 201 is used to perform, based on the latitude, longitude and elevation information of the ground pointing point of the load visual axis at several moments cached by the control system computer, estimating the longitude, longitude and elevation information of the target:

[0103] The control system computer sets the cache queue depth of its own information according to the delay time from the exposure of the payload detection information to the arrival of the control system, which shall not be less than three times of the delay time. When scanning and imaging begins, the cache queue is automatically maintained by using the strategy of pushing in new data and deleting the oldest data. The self-information includes: the longitude, latitude, elevation and corresponding time scale information of the ground pointing point of the payload visual axis.

[0104] The Newton interpolation method is used to interpolate and fit the latitude, longitude and elevation information of the payload sight axis ground pointing point at several cached moments to determine the latitude, longitude and elevation of the payload sight axis ground pointing point at the target detection moment, and use it as the estimated latitude, longitude and elevation of the target.

[0105] In one embodiment of the present invention, the recapture unit 202 is used to perform:

[0106] S1, record the current on-board time and the attitude information of the three axes at the current time; the three axes are the roll axis, the pitch axis and the yaw axis, and the attitude information includes the attitude angle, the attitude angular velocity and the attitude angular acceleration.

[0107] S2, determining the initial value of the iteration of the time T from the current moment to the target recapture moment, that is, the minimum value of the switching time from the current posture to the target gaze posture.

[0108] S3, the current satellite orbit information is extrapolated for T seconds, combined with the longitude, latitude and altitude information of the target determined by the estimation unit 201, and the expected attitude angle φ of the three axes at time t+T is calculated using the low-Earth orbit ground target point gaze target attitude calculation method im, expected attitude angular velocity and the expected angular acceleration The roll angle deviation Δφ and pitch angle deviation Δθ output by the load are used to correct the desired attitude angle at time t+T to obtain the recapture attitude at time t+T.

[0109] S4, using a fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the recapture attitude information at the time t+T, determine the fifth-order polynomial coefficients of the guidance process required to establish the tracking imaging attitude and the satellite attitude at each moment;

[0110] S5, determining whether the satellite attitude at each moment in the guidance process satisfies the system's maximum attitude maneuverability limit;

[0111] S6, if not satisfied, increase the time T according to the set step length. If the time T does not exceed the maximum threshold, jump to step S3, otherwise abandon the current tracking imaging and maintain the scanning imaging state.

[0112] S7, if satisfied, the control system performs closed-loop control based on the fifth-order polynomial coefficients of the guidance process, time T and the satellite attitude at each moment, and establishes the required attitude for payload target recapture at time t+T.

[0113] In one embodiment of the present invention, the tracking unit 203 performs tracking imaging in the following manner:

[0114] The control system enters the relative error control state. According to the roll angle deviation Δφ and pitch angle deviation Δθ output by the load (after t+T), the control attitude angle error and attitude angular velocity error are calculated and closed-loop controlled to control the target at the center of the load field of view. At the same time, the load performs continuous tracking imaging.

[0115] In one embodiment of the present invention, the return unit 204 is used to execute:

[0116] H1, records the current on-board time t, and the attitude information of the three axes at the current time; the three axes are the roll axis, pitch axis and yaw axis, and the attitude information includes the attitude angle, attitude angular velocity and attitude angular acceleration.

[0117] H2, determine the initial value of the iteration of the time T from the current time to the moment of establishing the scanning imaging posture, that is, the minimum value of the switching time from the current posture to the scanning imaging posture.

[0118] H3, the current satellite orbit information is extrapolated for T seconds, and the target attitude calculation method of the original scanning imaging state is used to calculate the expected attitude angle φ of the three axes at time t+T im , expected attitude angular velocity and the expected angular acceleration

[0119] H4, using the fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the scanning imaging attitude at the moment t+T, determines the fifth-order polynomial coefficients of the guidance process required to return to the scanning imaging state and the satellite attitude at each moment.

[0120] H5, determines whether the satellite attitude at each moment in the guidance process meets the system's maximum attitude maneuverability value limit.

[0121] H6, if not satisfied, increase the time T according to the set step length and jump to step H3.

[0122] H7, if satisfied, the control system performs closed-loop control according to the fifth-order polynomial coefficients of the guidance process, time T and the satellite attitude at each moment, and establishes the attitude required for the original payload scanning imaging of the estimation unit 201 at time t+T.

[0123] In one embodiment of the present invention, the reset unit 205 is used to execute:

[0124] When the satellite inertial angular velocity is less than the threshold and the dual star sensor is valid, the attitude quaternion q is determined by using the optical axis information of the star sensor through the standard dual-vector attitude determination method. s .

[0125] Using inertial angular velocity information to determine the quaternion q of the star sensor dual vector s Time compensation is performed, and the compensation time is the delay time Δt of the optical axis measurement information of the star sensor reaching the controller.

[0126] Using q s Assign a value to the current inertial posture once, update the current inertial posture, and do not assign a value again within a certain time range.

[0127] It should be noted that the hotspot target tracking device based on load detection and star sensitivity reset provided in the above embodiment is only illustrated by the division of the above functional units. In actual applications, the above functions can be assigned to different functional units as needed, that is, the internal structure of the device can be divided into different functional units to complete all or part of the functions described above. In addition, the above device embodiment and the method embodiment belong to the same concept, and the specific implementation process is detailed in the method embodiment, which will not be repeated here.

[0128] The embodiment of the present application also provides a computer device, please refer to Figure 3 The computer device includes a processor and a memory, in which a computer program required to implement the method is stored. The computer program is loaded and executed by the processor to implement the hotspot target tracking method based on load detection and star sensitivity reset provided by the above-mentioned method embodiments.

[0129] An embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is loaded and executed by a processor, the hot spot target tracking method based on load detection and star sensitivity reset provided by the above-mentioned method embodiments is implemented.

[0130] For the convenience of description, the above system or device is described by dividing it into various modules or units according to its functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0131] It can be known from the description of the above implementation methods that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly contributed to the prior art in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which can be a satellite computer, a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0132] Finally, it should be noted that, in this article, relational terms such as first, second, third and fourth are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0133] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A hotspot target tracking method based on load detection and star sensitivity reset, characterized in that: include: 100, when the payload finds a target in the scanning imaging state, the control system estimates the longitude, latitude and elevation of the target based on the target measurement and time scale information output by the payload and the longitude, latitude and elevation information of the ground pointing point of the payload's visual axis at several moments that are pre-cached; wherein the payload includes a camera and an image processing unit for extracting target measurement information; the target measurement information includes the time scale, the rolling angle deviation and the pitch angle deviation of the target center from the payload's visual axis; 102, based on the target latitude, longitude and elevation information determined in step 100, the roll angle deviation and pitch angle deviation output by the payload, according to the system maximum attitude maneuverability and the fifth-order polynomial guidance model loop iteration, determine the fastest time for target recapture, autonomously plan the target attitude of the target recapture process and perform closed-loop control, and establish the attitude required for payload target recapture; 104, after the target is recaptured, the attitude angle error and attitude angular velocity error for control are determined based on the target measurement information stably output by the payload after recapture, and a relative attitude closed-loop control is performed to ensure that the target is located at the center of the payload field of view, while the payload performs tracking imaging; 106, after the tracking imaging is completed, the target posture of the whole process of returning to the scanning imaging state is autonomously planned according to the system's maximum posture maneuverability and the fifth-order polynomial guidance model, and closed-loop control is performed to re-establish the posture required for the scanning imaging state in step 100; 108. In steps 100 to 106, when the satellite inertial angular velocity is less than a threshold value, the angular velocity information is used to perform time compensation on the dual-vector attitude quaternion of the star sensor, and the inertial attitude of the satellite is reset.

2. The method according to claim 1, characterized in that According to the target measurement and time stamp information output by the payload, and based on the pre-cached longitude, latitude and elevation information of the ground pointing point of the payload line of sight at several moments, the longitude, latitude and elevation of the target are estimated, including: The control system computer caches the latitude and longitude, elevation and time scale information of the ground pointing point of the load visual axis at a historical moment not less than three times the delay time from the exposure of the imaging to the arrival of the load detection information at the control system; when the scanning imaging starts, the strategy of pushing in new data and deleting the oldest data is adopted to automatically maintain the cache queue; The Newton interpolation method is used to interpolate and fit the latitude, longitude and elevation information of the payload sight axis ground pointing point at several cached moments to determine the latitude, longitude and elevation of the payload sight axis ground pointing point at the target detection moment, and use it as the estimated latitude, longitude and elevation of the target.

3. The method according to claim 1, characterized in that The onboard control system establishes the attitude required for payload target recapture in the following manner: S1, recording the current on-board time t and the attitude information of the three axes at the current time; wherein the three axes are the roll axis, the pitch axis and the yaw axis, and the attitude information includes the attitude angle, the attitude angular velocity and the attitude angular acceleration; S2, determine the initial value of the time T from the current time to the target recapture time, and iterate from small to large; S3, extrapolating the current satellite orbit information for a time of T seconds, combining the latitude, longitude and elevation information of the target determined in step 100, and using the near-Earth orbit ground target point gaze target attitude calculation method to calculate the expected attitude angle, expected attitude angular velocity and expected angular acceleration of the three axes at time t+T, and using the roll angle deviation and pitch angle deviation output by the payload to correct the expected roll attitude angle and pitch attitude angle at time t+T, to obtain the recapture attitude at time t+T; S4, using the fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the recapture attitude information at the time t+T, determine the fifth-order polynomial coefficients of the guidance process required to establish the tracking imaging attitude and the satellite attitude at each moment, and the whole process is smoothly connected; S5, determining whether the satellite attitude at each moment in the guidance process satisfies the system's maximum attitude maneuverability limit; S6, if not satisfied, increase the time T according to the set step length. If the time T does not exceed the maximum threshold, jump to step S3, otherwise abandon the current tracking imaging and maintain the scanning imaging state; S7, if satisfied, the control system performs closed-loop control based on the fifth-order polynomial coefficients of the guidance process, time T and the satellite attitude at each moment, and establishes the required attitude for payload target recapture at time t+T.

4. The method according to claim 1, characterized in that The control system enters the relative error control state. The method for determining the attitude angle error and attitude angular velocity error for control based on the target measurement information of the stable output of the load after recapture is: f bias =Df-f err ,the bias =Δθ-θ err f err =φ err +m·φ bias ,the err =θ err +m·θ bias , Among them, φ err ,θ err , are the attitude angle errors of the roll axis, pitch axis, and yaw axis, which are initialized to 0 when entering for the first time; φ bias and θ bias is an intermediate variable, meaning the correction introduced by load measurement information; They are the attitude angular velocity errors of the roll axis, pitch axis, and yaw axis, which are initialized to 0 when entering for the first time; m and n are correction coefficients.

5. The method according to claim 1, characterized in that After the tracking imaging is completed, the target posture of the whole process of returning to the scanning imaging state is autonomously planned and closed-loop control is performed according to the system's maximum posture maneuverability and the fifth-order polynomial guidance model, and the posture required for the scanning imaging state in step 100 is re-established, including: H1, records the current on-board time t, and the attitude information of the three axes at the current time; wherein the three axes are the roll axis, the pitch axis and the yaw axis, and the attitude information includes the attitude angle, the attitude angular velocity and the attitude angular acceleration; H2, determine the initial value of the time T from the current time to the moment of establishing the scanning imaging posture, and iterate from small to large; H3, extrapolate the current satellite orbit information for T seconds, and calculate the expected attitude angle, expected attitude angular velocity and expected angular acceleration of the three axes at time t+T based on the target attitude calculation method of the scanning imaging state; H4, using the fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the scanning imaging attitude at the time t+T, determines the fifth-order polynomial coefficients of the guidance process required for returning to the scanning imaging and the satellite attitude at each moment, and the whole process is smoothly connected; H5, determine whether the satellite attitude at each moment in the guidance process meets the system's maximum attitude maneuverability value limit; H6, if not satisfied, increase the time T according to the set step length and jump to step H3; H7, if satisfied, the control system performs closed-loop control based on the fifth-order polynomial coefficients of the guidance process, time T and the satellite attitude at each moment, and establishes the attitude required for the original payload scanning imaging at time t+T.

6. The method according to claims 3 and 5, characterized in that Using the fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the attitude information at the moment t+T, the method for determining the fifth-order polynomial coefficients of the guidance process and the satellite attitude at each moment is as follows: b i0 =φ i0 , Among them, t r is relative time; b ik is the k-order coefficient of the i-axis; φ i0 , and are respectively the attitude angle, attitude angular velocity and attitude angular acceleration of the i-axis at the current time t on the satellite; φ im , and are the expected attitude angle, expected attitude angular velocity and expected angular acceleration of the i-axis at time t+T respectively; φ ri (t r ), and t r Satellite attitude angle, attitude angular velocity and attitude angular acceleration of axis i at time i; i=x, y, z represent the roll axis, pitch axis and yaw axis respectively.

7. The method according to any one of claims 1 to 5, characterized in that When the satellite inertial angular velocity is less than a threshold value, the angular velocity information is used to perform time compensation on the dual-vector attitude quaternion of the star sensor and reset the inertial attitude of the satellite, including: When the satellite inertial angular velocity is less than the threshold and the dual star sensor is valid, the attitude quaternion q is determined by using the optical axis information of the star sensor through the standard dual-vector attitude determination method. s , to ensure accuracy; Using inertial angular velocity information to determine the quaternion q of the star sensor dual vector s Perform time compensation, the compensation time is the delay time Δt of the optical axis measurement information of the star sensor reaching the controller; Using q s Assign a value to the current inertial posture once, update the current inertial posture, and do not assign a value again within a certain time range.

8. A hotspot target tracking device based on load detection and star sensitivity reset, used to implement the steps of any of the methods described in claims 1-7 above, characterized in that: The device comprises: An estimation unit, used for, when the payload finds a target in the scanning imaging state, the control system estimates the longitude, latitude and elevation of the target based on the target measurement and time scale information output by the payload, and based on the longitude, latitude and elevation information of the ground pointing point of the payload's visual axis at several moments pre-cached; wherein, the payload includes a camera and an image processing unit for extracting target measurement information; the target measurement information includes the time scale, the rolling angle deviation and the pitch angle deviation of the target center from the payload's visual axis; The recapture unit is used to use the target latitude, longitude and elevation information determined by the estimation unit, the roll angle deviation and pitch angle deviation output by the payload, and the maximum attitude maneuverability of the system and the fifth-order polynomial guidance model loop iteration to determine the fastest time for target recapture, autonomously plan the target attitude of the target recapture process and perform closed-loop control to establish the attitude required for payload target recapture; The tracking unit is used to determine the attitude angle error and attitude angular velocity error for control based on the target measurement information stably output by the payload after recapture after the payload completes target recapture, and perform relative attitude closed-loop control to ensure that the target is located at the center of the payload's field of view, while the payload performs tracking imaging; The return unit is used to autonomously plan the target posture of the whole process of returning to the scanning imaging state according to the system's maximum posture maneuverability and the fifth-order polynomial guidance model after the payload tracking imaging is completed, and to perform closed-loop control to re-establish the posture required for the scanning imaging state in the estimation unit; The reset unit is used to use the angular velocity information to perform time compensation on the dual-vector attitude quaternion of the star sensor and reset the inertial attitude of the satellite when the inertial angular velocity of the satellite is less than a threshold value.

9. A computer device, characterized in that: The computer device includes a memory and a processor, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the steps of any one of the methods described in claims 1-7.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 7 are implemented.

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