Hot spot target tracking method and device based on load detection and star reset

Abstract

The application discloses a hotspot target tracking method and device based on load detection and star sensitivity reset, and belongs to the field of spacecraft attitude control. The method comprises the following steps: according to the time scale of load target detection information and historical load visual axis ground pointing point information, the latitude, longitude and altitude information of the target are estimated; according to the maximum attitude maneuvering ability of the system and the five-order polynomial guide model, the fastest time of target recapture is determined by taking time as an iteration amount, the target attitude of the target recapture process is autonomously planned, and closed-loop control is carried out; after the target recapture, the control system carries out closed-loop control according to the real-time detection information of the load, ensures that the target is located at the center of the visual field of the load, and the load continuously images; after the tracking imaging is completed, the guide process of returning to scanning imaging is autonomously planned; in the whole process, the current attitude is reset according to the double-vector attitude determination result of the high-precision star sensitive sensor with angular velocity as a constraint, so that the pointing accuracy is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spacecraft attitude control, and particularly relates to a hot target tracking method and device based on on-board load detection and star sensor reset. BACKGROUND

[0002] High-performance remote sensing satellites generally have high spatial resolution imaging requirements, hot target dense imaging requirements, and continuous tracking imaging of curved targets, and thus require strong attitude agility maneuvering capability, ultra-high pointing accuracy and ultra-high stability, and have the potential for target continuous tracking imaging from the hardware configuration.

[0003] However, traditional high-performance remote sensing satellites are only execution ends and do not realize automatic detection of hot targets on board and tracking imaging. Instead, the satellite attitude is manually controlled by ground personnel for imaging according to the positions of hot targets, and the task closed loop link is long. For hot targets with a certain moving speed, the long task link can also cause the target to be lost when imaging again.

[0004] With the use of intelligent algorithms, sensitive targets in the imaging area can be automatically detected on board. If the target is automatically tracked and continuously imaged on board, the user's intelligence acquisition capability can be greatly improved. However, there is no mature solution at present. Meanwhile, the target motion speed on the ground is relatively small compared with the satellite. The satellite needs to be in a high angular speed state. During the autonomous tracking process of the hot target, if the existing attitude maneuvering strategy of continuous integration of the gyroscope is directly used, the attitude setting deviation will gradually accumulate, and then the pointing accuracy will gradually deteriorate.

[0005] Therefore, there is an urgent need to provide a hot target tracking method and device based on load detection and star sensor reset. SUMMARY

[0006] The present application provides a hot target tracking method and device based on load detection and star sensor reset. The control system can extract hot target information based on on-board load during scanning imaging, autonomously and as soon as possible enter the target staring imaging process according to the maximum attitude maneuvering capability of the system, and establish the required attitude, realize continuous imaging of the load for the target, and autonomously return to the scanning imaging state after the tracking imaging is completed.

[0007] In a first aspect, a hot target tracking method based on load detection and star sensor reset is provided, comprising:

[0008] 100. When the payload detects a target in the scanning imaging state, the control system estimates the target's latitude, longitude, and elevation based on the target measurement and time scale information output by the payload, and on the latitude, longitude, and elevation information of the ground pointing point of the payload's line of sight at several pre-cached times. The payload includes a camera and an image processing unit for extracting target measurement information. The target measurement information includes the time scale, the roll angle deviation of the target center distance from the payload's line of sight, and the pitch angle deviation.

[0009] 102. Based on the target latitude, longitude and elevation information determined in step 100, the roll angle deviation and pitch angle deviation of the load output, and the maximum attitude maneuverability of the system and the fifth-order polynomial guidance model are iterated to determine the fastest time for target re-acquisition, autonomously plan the target attitude of the target re-acquisition process and perform closed-loop control, and establish the attitude required for load target re-acquisition.

[0010] 104. After the target is reacquired, the attitude angle error and attitude angular velocity error for control are determined based on the target measurement information output by the load after reacquisition, and relative attitude closed-loop control is performed to ensure that the target is located at the center of the load's field of view, while the load performs tracking imaging.

[0011] 106. After the tracking imaging is completed, the system autonomously plans the target attitude for the entire process of returning to the scanning imaging state based on the system's maximum attitude maneuverability and the fifth-order polynomial guidance model, and performs closed-loop control to re-establish the attitude required for the scanning imaging state in step 100.

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

[0013] Secondly, a hotspot target tracking device based on load detection and star-sensor reset is provided to implement the steps described in the embodiments of this specification, including:

[0014] An estimation unit is used to estimate the latitude, longitude, and elevation of a target when the payload detects a target in scanning imaging mode, based on the target measurement and time-stamp information output by the payload, and based on the latitude, longitude, and elevation information of the ground pointing point of the payload's line of sight at several pre-cached times. The payload includes a camera and an image processing unit for extracting target measurement information. The target measurement information includes a time-stamp, the roll angle deviation of the target center distance from the payload's line of sight, and the pitch angle deviation.

[0015] The recapturing unit is used for determining the fastest time of target recapturing, autonomously planning the target attitude of the target recapturing process and performing closed-loop control, and establishing the attitude required for target recapturing of the payload, according to the maximum attitude maneuvering capability of the system and the five-order polynomial guidance model, and the target longitude and latitude and height information determined by the estimating unit, the roll angle deviation and the pitch angle deviation output by the payload, and the like.

[0016] The tracking unit is used for determining the control attitude angle error and the attitude angle velocity error based on the target measurement information stably output by the payload after recapturing, and performing relative attitude closed-loop control, so as to ensure that the target is located at the center of the field of view of the payload while the payload is performing tracking imaging.

[0017] The returning unit is used for autonomously planning the target attitude of the whole process of returning scanning imaging state and performing closed-loop control, and re-establishing the attitude required for scanning imaging state in the estimating unit, according to the maximum attitude maneuvering capability of the system and the five-order polynomial guidance model, after the payload finishes tracking imaging.

[0018] The resetting unit is used for time compensating the double-vector attitude quaternion of the star sensor by using the angular velocity information, and resetting 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, which 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 realize the steps of the above method.

[0020] In a fourth aspect, a computer readable storage medium is provided, which stores a computer program, and the computer program is executed by a processor to realize the steps of the above method.

[0021] The application provides a hotspot target tracking method and device based on payload detection and star sensor resetting, based on which, the control system and the payload system autonomously cooperate to realize in-orbit autonomous tracking imaging of the hotspot target, and break the long task closed-loop link caused by the traditional remote sensing satellite as an execution end, and can greatly improve the target information acquisition capability. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0023] Figure 1A flow chart of a hot target tracking method based on load detection and star sensor reset is provided by the embodiment of the present application.

[0024] Figure 2 A device structure diagram of a hot target tracking device based on load detection and star sensor reset is provided by the embodiment of the present application.

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

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0027] The idea of the present application is to utilize the target detection information output by the on-board image processing unit, to determine the fastest time of target recapture, to autonomously plan the target attitude of the target recapture process and to enter the target gazing process according to the time cycle iteration method, with the satellite maximum attitude maneuvering capability and attitude control torque smoothing as constraints. The control system and the load system autonomously cooperate to realize the on-orbit autonomous tracking imaging of the hot target. After the load tracking imaging is completed, the attitude of the return scanning imaging state guiding process is autonomously planned. Meanwhile, in the whole process, the angular velocity information is utilized to time-compensate the double-vector attitude quaternion of the star sensor, and the inertia attitude of the satellite is reset at an appropriate time, so as to solve the problem of continuous error accumulation caused by gyro continuous integration and to ensure the pointing accuracy.

[0028] The specific implementation mode of the above idea will be described below.

[0029] Please refer to Figure 1 The hot target tracking method based on load detection and star sensor reset provided by the embodiment of the present application is applied to an on-board control system, and the method comprises the following steps.

[0030] In step 100, when the target is found by the scanning imaging state load, the control system estimates the longitude, latitude and elevation of the target according to the target measurement and time mark information output by the load and based on the pre-cached longitude, latitude and elevation information of the ground pointing point of the load viewing axis at several time points.

[0031] Step 102, based on the target longitude and latitude and elevation information determined in step 100, the roll angle deviation and pitch angle deviation output by the load, according to the maximum attitude maneuvering capability of the system and the five-order polynomial guidance model, the fastest time of target recapture is determined, the target attitude of the target recapture process is autonomously planned and closed-loop controlled, and the attitude required for the target recapture of the load is established.

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

[0033] Step 106, after tracking imaging, the target attitude of the whole process of returning to the scanning imaging state is autonomously planned and closed-loop controlled according to the maximum attitude maneuvering capability of the system and the five-order polynomial guidance model, and the attitude required in step 100 in the scanning imaging state is re-established.

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

[0035] In the embodiment of the application, it is necessary to ensure that the roll axis and pitch axis of the on-board control system are consistent with the roll axis and pitch axis of the load output information. If they are not consistent, conversion is needed before output to the control system or before the control system applies the method.

[0036] The execution mode of each step is described below. Figure 1

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

[0038] Firstly, according to the delay time from imaging exposure to the arrival of the control system, the cache queue depth of the control system computer itself information is set to be not less than three times of the delay time. When the scanning imaging starts, the strategy of pushing new data and deleting the oldest data is adopted to automatically maintain the cache queue. The self information includes the longitude, latitude and elevation of the ground pointing point of the load viewing axis and the corresponding time tag information.

[0039] Secondly, the control system obtains the target measurement information output by the load, and based on the cached longitude, latitude and elevation of the ground pointing point of the load viewing axis at several time points, the Newton interpolation method is used to obtain the longitude, latitude and elevation of the ground pointing point of the load viewing axis at the target detection time, which is taken as the estimated value of the longitude, latitude and elevation of the target. The target measurement information includes the time tag t0, the roll angle deviation Δφ and the pitch angle deviation Δθ of the target center from the load viewing axis.

[0040] ​For example, assuming the delay time for load detection information to reach the control system is 2 seconds, and the load scans the target at 3:00 (i.e., target measurement time t0), and the target measurement information is transmitted to the control system at 3:02, the control system's buffer queue at this time must contain at least the latitude, longitude, and elevation information of the load's line-of-sight ground pointing point from 2:59:56 to 3:02. It can be seen that buffering the latitude, longitude, and elevation information of the load's line-of-sight ground pointing point at historical times, which is at least three times the delay time, ensures that the target measurement time is within the corresponding time range of the buffer queue. Therefore, when the buffer queue does not contain the latitude, longitude, and elevation information of the load's line-of-sight ground pointing point at the corresponding time of the target measurement, the latitude, longitude, and elevation information of the load's line-of-sight ground pointing point at that time can be estimated using Newton's interpolation method. Given the small field of view of the load, the latitude, longitude, and elevation information of the load's line-of-sight ground pointing point at the target measurement time t0 is directly used as the target's latitude, longitude, and elevation information.

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

[0042] S1 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.

[0043] Let the attitude angle, attitude angular velocity, and attitude angular acceleration of the three axes at the current time t on the satellite be φ. i0 , Where i = x, y, z, representing the roll axis, pitch axis, and yaw axis, respectively. Continuing with the example above, the current onboard time t should be 3.02 seconds.

[0044] S2, determine the initial value of the time T from the current position to the target re-acquisition time, which is the minimum switching time from the current attitude to the target staring attitude. In this embodiment, the initial value of T is set to 2s.

[0045] S3, the current satellite orbit information is extrapolated over time T seconds. Combined with the latitude, longitude, and elevation information of the target determined in step 100, the expected attitude angles φ of the three axes at time t+T are calculated using the near-Earth orbit ground target point staring target attitude calculation method. im Desired attitude angular velocity and desired angular acceleration

[0046] The desired attitude angle at time t+T is corrected using the roll angle deviation Δφ and pitch angle deviation Δθ from the load output. 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 These are the x-axis attitude angle and y-axis attitude angle in the recapture attitude at time t+T, respectively.

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

[0051] Based on the time T and the fifth-order polynomial model, the polynomial coefficients of the x, y, and z-axis guiding processes are obtained using the following method:

[0052]

[0053] The fifth-order polynomial is defined as follows: t r For relative time; b ik φ is the k-th order coefficient of the i-axis; i0 , These represent the attitude angle, attitude angular velocity, and attitude angular acceleration along the i-axis at the current time t on the satellite; φ im , and Let be the desired attitude angle, desired attitude angular velocity, and desired angular acceleration along the i-axis at time t+T, respectively.

[0054] Next, calculate each relative time. Satellite attitude φ at time ri (t r ), attitude angular velocity and attitude angular acceleration The satellite attitude at each moment during the guidance process is given by the following formula:

[0055]

[0056] S5 determines whether the satellite attitude at each moment during the guidance process meets the system's maximum attitude maneuvering capability limit.

[0057] S6. If not satisfied, increase time T by the set step size. If time T does not exceed the maximum threshold, jump to step S3. Otherwise, discard the current tracking imaging and maintain the scanning imaging state.

[0058] In this embodiment, if all three axes There exists a time in the time that does not satisfy the condition. If the condition is not met, it is considered that the maximum attitude maneuverability limit is met; otherwise, it is considered that the limit is met. Where χ...max the maximum Euler angle allowed for the satellite, 60° in this embodiment; v max the maximum angular velocity allowed for the satellite, 3° / s in this embodiment; a max the maximum angular acceleration allowed for the satellite, 2° / s in this embodiment 2 .

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

[0060] S7, if the condition is met, the control system performs closed-loop control according to the five-order polynomial coefficients of the guidance process, the time T and the satellite attitude at each moment, and establishes the target recapture attitude required by the load at time t+T.

[0061] In summary, the load will complete the target recapture at time t+T, and thereafter, the target measurement information is stably output, i.e. the target measurement time tag t0, the roll angle deviation Δφ of the target center from the load visual axis and the pitch angle deviation Δθ.

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

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

[0064] The method for determining the attitude angle error and attitude angular velocity error according to 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] wherein φ err , θ err , are the roll axis, pitch axis and yaw axis attitude angle errors, respectively, and are initialized to 0 when first entered; φ bias and θ biasis a middle variable, and means a correction amount introduced by the load measurement information; are the roll, pitch and yaw attitude angular velocity errors, respectively, and are initialized to 0 when first entered; m and n are correction coefficients, and in this embodiment are taken as 0.1 and 0.01, respectively.

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

[0070] After the load tracking imaging is completed, the target attitude of the whole process of returning to the scanning imaging state is autonomously planned according to the maximum attitude maneuvering capability of the system and the five-order polynomial guidance model, and the load continues to scan and image.

[0071] H1, 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;

[0072] record the attitude angle, the attitude angular velocity and the attitude angular acceleration of the three axes at the current on-board time t as where i=x, y, z, respectively represent the roll axis, the pitch axis and the yaw axis.

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

[0074] H3, extrapolate the satellite orbit information for T seconds, and calculate the expected attitude angle φ im of the three axes at the time t+T using the original scanning imaging state target attitude calculation method.

[0075] H4, using the five-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, determine the five-order polynomial coefficients of the guidance process of returning to the scanning imaging state and the satellite attitude at each time.

[0076] According to the time T and the five-order polynomial model, the polynomial coefficients of the guidance process of the x, y and z axes are calculated, and the specific method is as follows:

[0077]

[0078] where the five-order polynomial is defined as t r is the relative time; b ik is the k-order coefficient of the i-axis; φ i0 , are the attitude angle, the attitude angular velocity and the attitude angular acceleration of the i-axis at the current on-board time t, respectively.​im , and are the desired attitude angle, the desired attitude angular velocity and the desired angular acceleration of the satellite at time t+T, respectively.

[0079] Then, the satellite attitude φ at each relative time ri (t r ), attitude angular velocity and attitude angular acceleration at each relative time

[0080]

[0081] H5, judge whether the satellite attitude at each time during the guiding process satisfies the system maximum attitude maneuverability value limit.

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

[0083] In the embodiment, if there is a time among all times that does not satisfy ri (t r ) |≤χ max , then it is judged as not satisfying, otherwise as satisfying the system maximum attitude maneuverability limit.

[0084] In the embodiment, the set step length is 0.5s.

[0085] H7, if satisfying, the control system performs closed-loop control according to the five-order polynomial coefficients of the guiding process, the time T and the satellite attitude at each time, and establishes the attitude required by the original payload scanning imaging at time t+T.

[0086] In summary, the payload will start scanning imaging and detecting new hot target again at time t+T, and the process of step 100 will be started again when the target is detected.

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

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

[0089] Then, the dual-vector attitude determination quaternion q s of the star sensor is corrected by using the inertial angular velocity information.Time compensation is performed, and the compensation time is the delay time Δt of the optical axis measurement information of the star sensor to the controller, and is specifically as follows:

[0090]

[0091] Δg|=norm(Δg)

[0092]

[0093] q s =M(Δg)·q s

[0094] Wherein, ω is the inertial angular velocity vector information in the time range of t-Δt~t; Δg is an intermediate variable, and Δg x , Δg y , Δg z X, y, z three-axis components of Δg respectively; Ω() and M() are intermediate functions, and have no real meaning; norm() is a modulus function; I4 is a 4-order unit matrix.

[0095] Finally, q s is assigned once to the current inertial attitude, and is not assigned again in a certain time range (30s in the embodiment).

[0096] Please refer to Figure 2 , the embodiment of the application provides a kind of hot target tracking device based on load detection and star reset, as a logical device, for realizing the steps of any method embodiment in the specification, device embodiment can be realized by software, also can be realized by hardware or software and hardware combination mode.The device comprises:

[0097] Estimation unit 201, for when scanning imaging state downloads load to find target, according to the target measurement and time mark information output by load, and based on the longitude and latitude and elevation information of the ground pointing point of several time load boresight pre-cached, estimate the longitude and latitude and elevation of target;Wherein, the load includes camera and image processing unit for extracting target measurement information;The target measurement information includes time mark, target center distance load boresight roll angle deviation and pitch angle deviation;

[0098] Recapture unit 202, for using the target longitude and latitude and elevation information determined by estimation unit, the roll angle deviation and pitch angle deviation output by load, according to the maximum attitude maneuverability of system and five-order polynomial guide model cyclic iteration, determine the fastest time of target recapture, autonomously plan target attitude of target recapture process and carry out closed loop control, establish the attitude required for load target recapture;

[0099] The tracking unit 203 is used for determining the control attitude angle error and attitude angular velocity error based on the target measurement information output by the payload after the target recapturing, and performing relative attitude closed-loop control to ensure that the target is located at the center of the field of view of the payload while the payload is performing tracking imaging.

[0100] The returning unit 204 is used for autonomously planning the target attitude of the whole process of returning scanning imaging state and performing closed-loop control after the payload tracking imaging is completed, so as to reestablish the attitude required by the scanning imaging state in the estimation unit.

[0101] The resetting unit 205 is used for performing time compensation on the double-vector attitude quaternion of the star sensor by using the angular velocity information when the satellite inertial angular velocity is less than a threshold value, and resetting the inertial attitude of the satellite.

[0102] In an embodiment of the present application, the estimation unit 201 is used for performing estimation of the longitude, latitude and altitude information of the target based on the longitude, latitude and altitude information of the ground pointing point of the payload visual axis at several time points stored in the control system computer cache:

[0103] The control system computer sets the cache queue depth of the self information according to the delay time from the imaging exposure to the arrival of the control system according to the payload detection information, and the queue depth is not less than three times of the delay time. When the scanning imaging is started, the strategy of pushing new data and deleting the oldest data is adopted to automatically maintain the cache queue. The self information includes the longitude, latitude and altitude of the ground pointing point of the payload visual axis and the corresponding time tag information.

[0104] The Newton interpolation method is used to perform interpolation fitting on the longitude, latitude and altitude information of the ground pointing point of the payload visual axis at several time points stored in the cache, so as to determine the longitude, latitude and altitude of the ground pointing point of the payload visual axis at the target detection time point, and the longitude, latitude and altitude are taken as the estimated values of the longitude, latitude and altitude of the target.

[0105] In an embodiment of the present application, the recapturing unit 202 is used for performing the following steps:

[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, determine the time T iteration initial value from the current attitude to the minimum switching time of the target gazing attitude.

[0108] S3, extrapolate the satellite orbit information for T seconds, combine the longitude, latitude and altitude information of the target determined by the estimation unit 201, and use the near-earth orbit ground target point gazing target attitude calculation method to calculate the expected attitude angle of the three axes at t+T time point imdesired attitude angular velocity and desired angular acceleration and the roll angle deviation Δφ and the pitch angle deviation Δθ outputted by the load, the desired attitude angle at the time t+T is corrected to obtain the recapturing attitude at the time t+T.

[0109] S4, based on the attitude information of the three axes at the current time t and the recapturing attitude information at the time t+T, the five-order polynomial coefficients of the guiding process required for establishing the tracking imaging attitude and the satellite attitude at each time are determined by using the five-order polynomial guiding model.

[0110] S5, it is judged whether the satellite attitude at each time in the guiding process satisfies the system maximum attitude maneuvering capability limit.

[0111] S6, if not, the time T is increased according to the set step, if the time T does not exceed the maximum threshold, the step S3 is executed, otherwise the tracking imaging is discarded and the scanning imaging state is maintained.

[0112] S7, if yes, the closed-loop control is performed according to the five-order polynomial coefficients of the guiding process, the time T and the satellite attitude at each time by the control system, and the attitude required for the target recapturing of the load is established at the time t+T.

[0113] In an embodiment of the present application, the tracking unit 203 performs the tracking imaging by the following way:

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

[0115] In an embodiment of the present application, the returning unit 204 is used to perform:

[0116] H1, the current time t on the satellite and the attitude information of the three axes at the current time are recorded; 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.

[0117] H2, the iteration initial value of the time T from the current time to the time when the scanning imaging attitude is established is determined, that is, the minimum value of the switching time from the current attitude to the scanning imaging attitude.

[0118] H3, the satellite orbit information at the current time is extrapolated for T seconds, the desired attitude angle φ im desired attitude angular velocity and desired angular acceleration

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

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

[0121] If H6 is not satisfied, then increase the time T by the set step size and jump to step H3.

[0122] 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 of estimation unit 201 at time t+T.

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

[0124] When the satellite's inertial angular velocity is less than the threshold and the dual-star sensors are effective, the attitude quaternion q is determined using the optical axis information of the star sensors through a standard two-vector attitude determination method. s .

[0125] Using inertial angular velocity information to determine the attitude of a star sensor using a dual-vector quaternion q s Time compensation is performed, with the compensation time being the delay Δt between the optical axis measurement information of the star sensor and the arrival time of the controller.

[0126] Using q s Assign a value to the current inertial attitude once, update the current inertial attitude, and then 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-sensor reset provided in the above embodiments is only an example of the division of the above functional units. In practical 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 embodiments and method embodiments belong to the same concept, and the specific implementation process can be found in the method embodiments, which will not be repeated here.

[0128] Embodiments of this application also provide 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-sensor reset provided in the above-described method embodiments.

[0129] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program. The computer program is loaded and executed by a processor to implement the load detection and star reset based hotspot target tracking method provided by the above method embodiments.

[0130] For the convenience of description, the above system or device is described in various modules or units in terms of functions. Of course, the functions of each unit can be implemented in the same or multiple software and / or hardware in the implementation of the present application.

[0131] From the above description of the embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software and the necessary general hardware platform. Based on this understanding, the technical solutions of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a star computer, a personal computer, a server, or a network device, etc.) execute the methods described in various embodiments or some parts of the embodiments of the present application.

[0132] Finally, it should be noted that in this document, relational terms such as first and second and third and fourth, and the like can merely be used to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between or among the entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0133] The above only describes the preferred embodiments of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A hotspot target tracking method based on load detection and star-sensor resetting, characterized in that, include:

100. When the payload detects a target in the scanning imaging state, the control system estimates the target's latitude, longitude, and elevation based on the target measurement and time scale information output by the payload, and on the latitude, longitude, and elevation information of the ground pointing point of the payload's line of sight at several pre-cached times. The payload includes a camera and an image processing unit for extracting target measurement information. The target measurement information includes the time scale, the roll angle deviation of the target center distance from the payload's line of sight, and the pitch angle deviation.

102. Based on the target latitude, longitude and elevation information determined in step 100, the roll angle deviation and pitch angle deviation of the load output, and the maximum attitude maneuverability of the system and the fifth-order polynomial guidance model are iterated to determine the fastest time for target re-acquisition, autonomously plan the target attitude of the target re-acquisition process and perform closed-loop control, and establish the attitude required for load target re-acquisition.

104. After the target is reacquired, the attitude angle error and attitude angular velocity error for control are determined based on the target measurement information output by the load after reacquisition, and relative attitude closed-loop control is performed to ensure that the target is located at the center of the load's field of view, while the load performs tracking imaging.

106. After the tracking imaging is completed, the system autonomously plans the target attitude for the entire process of returning to the scanning imaging state based on the system's maximum attitude maneuverability and the fifth-order polynomial guidance model, and performs closed-loop control to re-establish the attitude required for the scanning imaging state in step 100.

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

2. The method as described in claim 1, characterized in that, Based on the target measurement and time-scale information output by the payload, and using the latitude, longitude, and elevation information of the ground pointing point of the payload line of sight at several pre-cached times, the latitude, longitude, and elevation of the target are estimated, including: The control system computer caches the latitude, longitude, elevation, and time-scale information of the ground pointing point of the load line of sight at a historical moment, which is no less than three times the delay time from the time the load detection information is exposed to the time it reaches the control system. When scanning and imaging begins, the computer automatically maintains this cache queue by pushing in new data and deleting the oldest data. The latitude, longitude, and elevation information of the ground pointing point of the load line of sight at several time points are interpolated and fitted using the Newton interpolation method to determine the latitude, longitude, and elevation of the ground pointing point of the load line of sight at the time of target detection, and these are used as the estimated values ​​of the target's latitude, longitude, and elevation.

3. The method as described in claim 1, characterized in that, The onboard control system establishes the attitude required for payload re-acquisition in the following manner: S1 records the current onboard time t and the attitude information of the three axes at the current time; wherein, 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; 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. Extrapolate the current satellite orbit information by time T seconds, combine it with the latitude, longitude and elevation information of the target determined in step 100, use the near-Earth orbit ground target point staring 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 use the roll angle deviation and pitch angle deviation of the load output to correct the expected roll attitude angle and pitch attitude angle at time t+T to obtain the re-acquisition attitude at time t+T. S4 utilizes a fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the re-acquisition attitude information at time t+T, to determine the fifth-order polynomial coefficients of the guidance process required to establish the tracking imaging attitude and the satellite attitude at each time, with the entire process seamlessly connected. S5, determine whether the satellite attitude at each moment in the guidance process meets the system's maximum attitude maneuvering capability limit; S6. If not satisfied, increase time T by the set step size. If time T does not exceed the maximum threshold, jump to step S3. Otherwise, discard the current tracking imaging and maintain the scanning imaging state. If S7 is 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 payload target re-acquisition at time t+T.

4. The method as described in claim 1, characterized in that, The control system switches to 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 load output after reacquisition is as follows: ， ， ， ， ， in, , , These are the attitude angle errors for the roll axis, pitch axis, and yaw axis, respectively, initialized to 0 upon first entry. and This is an intermediate variable, representing the correction amount introduced by the load measurement information; , , These are the attitude angular velocity errors for the roll axis, pitch axis, and yaw axis, respectively, initialized to 0 upon first entry. and All are correction factors.

5. The method as described in claim 1, characterized in that, After tracking and imaging is completed, the system autonomously plans the target attitude for returning to the scanning imaging state throughout the entire process based on the system's maximum attitude maneuverability and the fifth-order polynomial guidance model, and performs closed-loop control to re-establish the attitude required for the scanning imaging state in step 100, including: H1 records the current onboard time t and the attitude information of the three axes at the current time; wherein, 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; H2 determines the initial value of the time T from the current moment to the moment of establishing the scanning imaging posture, and iterates from small to large; H3 extrapolates the current satellite orbit information by time T seconds, and calculates 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 utilizes a fifth-order polynomial guidance model to determine the fifth-order polynomial coefficients and satellite attitude at each moment of the guidance process required for returning to the scanning image, based on the attitude information of the three axes at the current time t and the scanning imaging attitude at time t+T. The entire process is smoothly connected. H5, determine whether the satellite attitude at each moment during the guidance process meets the system's maximum attitude maneuverability limit; If H6 is not satisfied, then increase the time T by the set step size 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 as described in claim 3 or 5, characterized in that, Using a fifth-order polynomial guidance model, based on the attitude information of the three axes at the current time t and the attitude information at time t+T, the method for determining the fifth-order polynomial coefficients of the guidance process and the satellite attitude at each time step is as follows: ， ， in, t r Relative time; for i shaft k Order coefficient; , and These are the current satellite time t. i The attitude angle, attitude angular velocity, and attitude angular acceleration of the axis; , and They are time points t+T respectively. i The desired attitude angle, desired attitude angular velocity, and desired angular acceleration of the axis; , and They are respectively t r time i The satellite attitude angle, attitude angular velocity, and attitude angular acceleration of the axis; i = x, y, z These represent the roll axis, pitch axis, and yaw axis, respectively.

7. The method according to any one of claims 1-5, characterized in that, When the satellite's inertial angular velocity is less than a threshold, the process of using the angular velocity information to perform time compensation on the dual-vector attitude determination quaternion of the star sensor and resetting the satellite's inertial attitude includes: When the satellite's inertial angular velocity is less than the threshold and the dual-star sensors are active, the attitude quaternion is determined using the optical axis information of the star sensors through a standard two-vector attitude determination method. To ensure accuracy; Using inertial angular velocity information to determine the attitude of a star sensor using a dual-vector quaternion Time compensation is performed, with the compensation time being the delay time between the optical axis measurement information from the star sensor and the arrival time at the controller. ; use Assign a value to the current inertial attitude once, update the current inertial attitude, and then do not assign a value again within a certain time range.

8. A hotspot target tracking device based on load detection and star-sensor reset, used to implement the steps of the method described in any one of claims 1-7, characterized in that, The device includes: An estimation unit is used to estimate the latitude, longitude, and elevation of a target when the payload detects a target in scanning imaging mode. This estimation is based on the target measurement and time-stamp information output by the payload, and on the latitude, longitude, and elevation information of the ground pointing point of the payload's line of sight at several pre-cached times. The payload includes a camera and an image processing unit for extracting target measurement information. The target measurement information includes a time-stamp, the roll angle deviation of the target center distance from the payload's line of sight, and the pitch angle deviation. The re-acquisition unit is used to utilize the target latitude, longitude and elevation information determined by the estimation unit, the roll angle deviation and pitch angle deviation output by the load, and iteratively determine the fastest moment for target re-acquisition based on the system's maximum attitude maneuverability and the fifth-order polynomial guidance model. It autonomously plans the target attitude during the target re-acquisition process and performs closed-loop control to establish the attitude required for load target re-acquisition. The tracking unit is used to determine the attitude angle error and attitude angular velocity error for control based on the target measurement information output by the load after the load completes target re-acquisition, and to perform relative attitude closed-loop control to ensure that the target is located at the center of the load's field of view, while the load performs tracking imaging. The return unit is used to autonomously plan the target attitude of the entire process of returning to the scanning imaging state after the payload tracking imaging is completed, based on the system's maximum attitude maneuverability and the fifth-order polynomial guidance model, and to perform closed-loop control, and to re-establish the attitude required for the scanning imaging state in the estimation unit. The reset unit is used to perform time compensation on the dual-vector attitude determination quaternion of the star sensor using angular velocity information when the satellite's inertial angular velocity is less than a threshold, and to reset the satellite's inertial attitude.

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

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the method described in any one of claims 1-7.

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