Photoelectric tracking control method based on inertia information assistance

Abstract

The invention provides a photoelectric tracking control method based on inertial information assistance. The photoelectric tracking control method comprises the following steps: S1, obtaining a projection vector of a target in a target surface system and a projection vector of the target in a target geographical system; s2, performing time synchronization on the miss distance and the measured angle by taking inertial navigation as a reference, and predicting a projection vector under a geographical system to obtain an elevation angle and an azimuth angle of a carrier system at the current moment; s3, performing time alignment of the measurement data and space alignment of the coordinate system and the measurement data, and correcting the angle measurement data; s4, carrying out updating frequency improvement and prediction on the target vector position by using carrier operation information measured by the inertial measurement unit, providing target indication data to form control parameters and guide information, controlling the detection head to turn to the target position according to the guide information, and after guiding to turn in place, returning to the target position. A given target is guided, captured and tracked, miss distance and a tracking state are returned in real time, a position closed loop of target tracking can be realized, and the tracking performance and stability of a system are improved.

Description

Technical Field

[0001] The present invention relates to the field of tracking and detection technology, and in particular to an optoelectronic tracking control method based on inertial information assistance. Background Art

[0002] In the field of optoelectronic tracking and detection technology, the factors that restrict the target tracking capability of the optoelectronic tracking system are mainly the excessively high miss delay and the low bandwidth of the servo control position loop, which cause unstable target tracking or even tracking loss in high sea conditions and large swings of the carrier, making it impossible to stably and continuously output the target's three-dimensional coordinate information.

[0003] At present, under the conditions of high-frequency vibration of the carrier, high sea conditions, and high miss delay, there are higher requirements for stable and continuous identification, following, and measurement of the targets sent by the system. The traditional miss distance image target tracking closed loop is no longer competent for such application scenarios. Therefore, a more effective target tracking control method is needed to improve the tracking performance and stability of optoelectronic tracking equipment.

[0004] In view of this, it is necessary to provide an optoelectronic tracking control method based on inertial information assistance to overcome the above defects. Summary of the invention

[0005] The purpose of the present invention is to provide an optoelectronic tracking control method based on inertial information assistance, which applies inertial navigation attitude data to optoelectronic target tracking, uses coordinate conversion to obtain its geographic orientation, and then reversely solves the turntable command angle to complete the tracking closed loop, which completely solves the delay problem of off-target caused by high-definition image reading, processing, and transmission, and improves the tracking capability and stability of the optoelectronic system in harsh environments such as high sea conditions, high maneuverability, and high-frequency vibration.

[0006] In order to achieve the above object, the technical solution provided by the present invention is implemented as follows: an optoelectronic tracking control method based on inertial information assistance comprises the following steps:

[0007] S1, based on the inertial information-assisted optoelectronic target tracking coordinate system transformation, the projection vector of the target in the target surface system and the projection vector of the target in the geographic system are obtained;

[0008] S2, target geographic system prediction, using inertial navigation as the reference to synchronize the miss distance and angle measurement, predict the projection vector under the geographic system, and obtain the altitude and azimuth of the load system at the current time;

[0009] S3, error calibration, aligning the time of the measured data and the coordinate system with the space of the measured data, and correcting the angle measurement data;

[0010] S4, target tracking control, uses the carrier operation information measured by the inertial measurement unit to increase and predict the target vector position update frequency, provides target indication data to form control parameters and guidance information, and controls the detection head to turn to the target position according to the guidance information. After the guidance is in place, it guides the capture and tracking of the given target and returns the miss distance and tracking status in real time.

[0011] Preferably, the specific process of step S1 is: the inertial measurement unit and the photoelectric measurement assembly are fixedly connected with the azimuth axis, and the pitch angle is θ, P XZ , P YZ are the unit target vectors In X L O L Z L and Y L O L Z L Projection, the coordinate systems are defined as follows:

[0012] b L : Target surface coordinate system, Z L is the optical axis; b p : Pitch axis fixed coordinate system, and b L coincide;

[0013] b p0 : Pitch axis zero position coordinate system, and b p Phase difference pitch angle θ;

[0014] b v : Rotation axis coordinate system; b v0 : Angle measurement zero position coordinate system; b s : Installation base coordinate system, with b v0 overlap; b i : imu coordinate system; n: geographic system.

[0015] The coordinate transformation process is as follows:

[0016] (1)b p With b p0 The conversion relationship between them is:

[0017]

[0018] Among them, C X (θ) represents a rotation of θ along the X axis;

[0019] (2)b v With b v0 The conversion relationship between them is:

[0020] Rotary azimuth angle value θ v0 ,but:

[0021]

[0022] Among them, C Z (θ v0 ) represents a rotation along the Z axis θ v0 ;

[0023] (3)b p With b L The conversion relationship between them is:

[0024]

[0025] (4) Projection vector of the target on the target surface

[0026] The angle corresponding to the miss distance is θ X =∠P XZ O L P Z ,θ Y =∠P Z O L P YZ , the target unit vector is expressed as the miss distance, and θ is calculated based on the plane geometry P =∠P XZ O L P, and then use θ X and θ P express:

[0027]

[0028] in:

[0029] tanθ P =tanθ Y cosθ X (4-5)

[0030] (5) Target is b s Projection

[0031]

[0032] Substituting formula (4-7) into (4-1), (4-3) and (4-4) yields:

[0033]

[0034] Among them, the azimuth angle is clockwise, if the azimuth angle θ is defined z =-θ v0 , then the above formula (4-8) can be written as:

[0035]

[0036] (6) Projection vector in the target geographic system

[0037]

[0038] in, It is the installation base, i.e. the carrier posture matrix.

[0039] Preferably, the specific process of step S2 is:

[0040] (1) Using the miss distance as a servo closed loop

[0041] Integrate formula (4-7) and formula (4-10), and add timestamps to the angle measurement, attitude and miss distance used:

[0042]

[0043] Among them, t 0 =t-Δt is the exposure time of the miss amount, Δt is generally obtained by prior estimation,

[0044] Rewriting formula (4-11) is:

[0045]

[0046] From formula (4-12), we can see that if we directly change t 0 Replace with t, then we have:

[0047]

[0048] From formulas (4-12) and (4-13), we can see that the interval [t 0 ,t] if there is Then the predicted miss distance vector Determined by the pitch angle, azimuth angle and attitude at the same time, and The relationship between them is:

[0049]

[0050] According to formulas (4-6) and (4-14), the predicted miss angle θ is calculated. Y ,θ X :

[0051]

[0052] Formula (4-15) is the predicted miss angle at the current moment.

[0053] Projection vector of miss distance under the carrier system With carrier height angle Hs and azimuth A s Indicates that the servo control also uses the carrier altitude angle and azimuth angle to close the loop, then and The relationship between:

[0054]

[0055] from The carrier altitude angle and azimuth angle calculated in the calculation can be used for servo tracking closed loop:

[0056]

[0057] Formula (4-17) is the altitude angle and azimuth angle of the load system at the current moment after prediction.

[0058] Preferably, the specific process of step S3 is as follows: error calibration is divided into time alignment of measurement data and space alignment of coordinate system and measurement data. Time alignment uses inertial navigation time as a reference, and uses navigation message timing to send luminous, radar and other measurement equipment, and timestamps the reported measurement data. The target positioning solution process uses the time-aligned data as a data source for calculation and output;

[0059] The specific process of spatial alignment of the coordinate system and the measurement data is:

[0060] Step 1: Initial alignment of optoelectronics and inertial navigation using landmarks.

[0061] Select a landmark, measure the latitude, longitude and elevation of the aiming point, and use the latitude, longitude and elevation of the optoelectronics to calculate the azimuth and elevation angle of the target relative to the optoelectronics, or directly measure its azimuth and elevation angle relative to the optoelectronics.

[0062] The optoelectronics system works normally, measuring the carrier coordinate system azimuth and pitch angle of the target, and recording the inertial navigation direction and attitude information at the same time. The carrier coordinate system azimuth and pitch angle are converted to the geographic coordinate system, and compared with the directly measured azimuth and pitch angle of the target to complete the optoelectronics zero calibration;

[0063] Step 2: Precise alignment of optoelectronics and inertial navigation satellite measurement.

[0064] With the help of visible light ephemeris, the stellar azimuth and pitch angle are calculated in real time using time and position information, optoelectronic guidance is implemented, and star tracking is performed using the visible light channel. The tracking miss amount is recorded and the azimuth and pitch angle are measured. The azimuth, pitch angle, inertial navigation heading and attitude information are calculated, and multiple star data are continuously measured. Each star has multiple sets of valid data. According to the optoelectronic axis system error model, the least squares method is used to calculate the optoelectronic axis system error to complete the calibration process.

[0065] Preferably, the specific process of step S4 is:

[0066] (1) Target vector acquisition,

[0067] During the period between target offset updates, the target's altitude and azimuth in the geographic coordinate system remain unchanged.

[0068] Therefore, the optical axis of the optoelectronic system needs to track the fixed geographic direction. The algorithm flow is as follows:

[0069] After the offset is updated, the inertial navigation attitude information is converted to the geographic coordinate system based on the angle measurement information. The formula is as follows:

[0070]

[0071] Among them, Rs is the target vector information on the target surface: R s =[xy 1] T , The target surface to carrier transformation matrix is ​​calculated using the inner ring angle measurement and the outer ring angle measurement:

[0072]

[0073] is the inertial navigation attitude matrix, which is calculated by the Euler angle provided by the inertial navigation. The formula is defined by the sequence and positive and negative of the inertial navigation Euler angle. The inertial measurement unit is used to measure the azimuth, pitch, and roll angles of the carrier based on the inertial space, which are ψ, θ, From the inertial system to the load system, after three coordinate transformations,

[0074] The inertial system rotates around the Z axis by an angle of ψ, then around the Y axis by an angle of θ, and then around the Z axis Angle, the coordinate transformation matrix from the inertial system to the load system is:

[0075]

[0076]

[0077] The output of the angular position compensation loop is the orientation of the inertial space of LOS as:

[0078]

[0079] Let A' g If A' is a unit vector, g λe and λa are used to represent: λe is the pitch angle in the LOS inertial system, and λa is the azimuth angle in the LOS inertial system.

[0080] A' g =[cosλe sinλ a cosλe cosλ a sinλ e ] T (6-5)

[0081] Then express A in the carrier system, and use the coordinate transformation matrix between the carrier system and the inertial system to get

[0082] Incident vector A b In the carrier coordinate system, it is represented as A b =[0 0 -1] T , then the ejection vector under the load system is:

[0083] A b '=[-sinαcosβ cosαcosβ sinβ] T (6-6)

[0084] From the above kinematic relationship, it can be inferred that the azimuth pitch angles α and β are given by the attitude matrix and the target inertia, that is, the kinematic relationship is defined:

[0085]

[0086] Where A' g =[cosλe sinλ a cosλe cosλ a sinλ e ] T The Euler angles given by the target inertia, A' g is represented by λe.λa, and By θ, ψ, Indicates that when the gyro sensor detects the angular velocity ω of the carrier mx ,ω my， ,ω mz , the real-time value of the quaternion can be solved by the fourth-order RK method to obtain the carrier attitude angle.

[0087] (2) Target vector update,

[0088] According to the real-time attitude information provided by the inertial navigation, the target geographic system vector calculated previously is converted to the carrier coordinate system:

[0089]

[0090] k means: the offset is updated for the kth time;

[0091] i means: after the offset is updated, the inertial navigation is updated for the i-th time;

[0092] Then, the target carrier system vector is used to obtain the azimuth and pitch loop control target angle.

[0093] (3) Target vector prediction,

[0094] Use 1000Hz gyro data to achieve 1000Hz high-frequency output and data prediction of attitude information.

[0095] The prediction formula is as follows:

[0096]

[0097] m means: update time scale of 200Hz gyro data;

[0098] 10 means: use 1 1000Hz gyro data to perform 10ms phase prediction;

[0099] The meaning of i is: the value of i is 1 to 5, indicating the 5 numbers interpolated in the 200Hz update. i is updated from 1 to 5 to realize the interpolation of 200Hz to 1000Hz attitude data.

[0100] (4) Control process,

[0101] Provide target indication data to form control parameters and control instructions (guidance information) and input them into the control system;

[0102] The control system controls the detection head to turn to the target position (geographic system) according to the guidance information, forms the in-position state and reports it, and adjusts the sensor field of view to the position according to the target distance;

[0103] After the guidance turns into place, the target position and target pixel size information provided by the recognition system (internal or external recognition results) are sent to the control system, and the image tracking module of the control system guides the capture and tracking of the given target, and returns the miss distance and tracking status to the control system in real time;

[0104] The control system determines the tracking status. After the miss distance data is valid, the image tracking module of the control system enters the tracking closed loop and determines the tracking status in real time.

[0105] Preferably, when the tracking state is normal, the control system controls the laser ranging and records the measurement data such as timestamp, hull attitude, angle measurement, miss distance, distance, etc. After measuring five sets of valid data continuously, the measurement is set to the measurement completion state, and the control system returns to the locked stable mode, waiting to enter the next target measurement process;

[0106] When the tracking status is abnormal, the control system switches back to the aiming mode and recaptures the tracking target through image guidance information. If the same target cannot be tracked for N consecutive cycles, the target is marked as unmeasurable, the control system switches to the locking stabilization mode, and reports the measurement results.

[0107] Compared with the existing technology, the beneficial effects are: 1) This method applies inertial navigation attitude data to optoelectronic target tracking, uses coordinate transformation to obtain its geographic orientation, and then reversely solves the turntable command angle to complete the tracking closed loop, which completely solves the delay problem of off-target distance caused by high-definition image reading, processing, and transmission, and improves the tracking capability and stability of the optoelectronic system in harsh environments such as high sea conditions, high maneuvers, and high-frequency vibrations.

[0108] 2) This method predicts and compensates the miss distance in the geographic coordinate system, which solves the problem that the miss distance motion trajectory in the target surface coordinate system is complex and difficult to model, and improves the optoelectronic system's tracking capability for high-speed moving targets.

[0109] 3) This method combines inertial space stabilization technology with optoelectronic tracking technology. When there is no miss distance data or the miss distance is unstable, it can ensure that the pointer will not be deviated by the wrong miss distance, and the tracking stability and robustness of the system can be improved.

[0110] 4) This method can be implemented based on the navigation information provided by shipborne, vehicle-borne and airborne main inertial navigation and the control fiber optic gyroscope information, and has the conditions for promotion and application in various types of shipborne, vehicle-borne and airborne optoelectronic systems of our institute. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0112] Figure 1 A partial structural schematic diagram of the schematic diagram of optoelectronic target tracking based on inertial information assistance provided by the present invention.

[0113] Figure 2 Schematic diagram of coordinate transformation from geographic system to carrier system.

[0114] Figure 3 Schematic diagram of the orientation of LOS in inertial space. DETAILED DESCRIPTION

[0115] In order to make the purpose, technical solution and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the present invention, not for limiting the present invention.

[0116] See also Figures 1 to 3 The present invention provides an optoelectronic tracking control method based on inertial information assistance, comprising the following steps:

[0117] S1, optoelectronic target tracking coordinate system transformation based on inertial information assistance;

[0118] like Figure 1 As shown, the inertial measurement unit (IMU) and the optoelectronic measurement assembly are fixedly connected to the azimuth axis, and the pitch angle is θ (head up is positive), P XZ , P YZ are the unit target vectors In X L O L Z L and Y L O L Z L Projection. The target is partially enlarged in the projection area on the target surface to facilitate the description of coordinate transformation. Figure 1 The coordinate systems in are defined as follows:

[0119] b L : Target surface coordinate system, Z L is the optical axis; b p : Pitch axis fixed coordinate system, and b L coincide;

[0120] b p0 : Pitch axis zero position coordinate system, and b p Phase difference pitch angle θ;

[0121] b v : Rotation axis coordinate system; b v0 : Angle measurement zero position coordinate system; b s : Installation base coordinate system, with b v0 overlap; b i : imu coordinate system; n: geographic system.

[0122] The coordinate transformation process is as follows:

[0123] (1)b p With b p0 The conversion relationship between them is:

[0124]

[0125] Among them, C X (θ) represents a rotation of θ along the X axis;

[0126] (2)b v With b v0 The conversion relationship between them is:

[0127] Rotary azimuth angle value θ v0 ,but:

[0128]

[0129] Among them, C Z (θ v0 ) represents a rotation along the Z axis θ v0 ;

[0130] (3)b p With b L The conversion relationship between them is:

[0131]

[0132] (4) Projection vector of the target on the target surface

[0133] Figure 1 In the figure, the angle corresponding to the miss distance is θ X =∠P XZ O L P Z ,θ Y =∠P Z O L P YZ The target unit vector is expressed as the miss distance, which can be expressed in two ways:

[0134] One is to calculate θ based on plane geometry P =∠P XZ O L P, and then use θ X and θ P express:

[0135]

[0136] in:

[0137] tanθ P =tanθ Y cosθ X (4-5)

[0138] Another approach is to use an approximate method, namely θ P ≈θ Y , using θ X and θ Y express.

[0139]

[0140] The premise of the approximation of formula (4-6) is that the miss angle θ of azimuth and height X ,θ Y are all small, or at least the azimuth miss amount θ X is a small amount. This approximation can adapt to most tracking scenarios in practical applications. However, there are also scenarios where the TV sensor has a large field of view, such as 40 degrees, and the target is near the edge of the field of view, i.e., θ X≈20°. When θ Y =10° to estimate θ P =9.4°, the phase difference between the two is θ Y -θ P =0.6°, therefore, the target unit vector should be expressed according to formula (4-4).

[0141] (5) Target is b s Projection

[0142]

[0143] Substituting formula (4-7) into (4-1), (4-3) and (4-4) yields:

[0144]

[0145] Among them, the azimuth angle is clockwise, if the azimuth angle θ is defined z =-θ v0 , then the above formula (4-8) can be written as:

[0146]

[0147] (6) Projection vector in the target geographic system

[0148]

[0149] in, It is the installation base, i.e. the carrier posture matrix.

[0150] The above formulas (4-4)-(4-10) represent the entire process of converting the target vector from the target surface coordinate system to the geographic system.

[0151] S2, target geographic department prediction;

[0152] In actual application scenarios, there is an exposure delay when the target is imaged on the target surface and a delay in the intermediate transmission, which leads to a delay in the actual output of the off-target amount.

[0153] Assuming there is an absolute time reference, the miss distance output at the current calculation time t has the actual exposure start time t 0 , the delay between the two is Δt=tt 0 If the miss distance delay is large, it will affect the target tracking stability. Considering that the attitude delay of 200 Hz or 1000 Hz inertial navigation is in the millisecond level, the miss distance and angle measurement can be synchronized based on the inertial navigation, and the projection vector in the geographic system can be predicted.

[0154] (1) Using the miss distance to perform servo tracking closed loop

[0155] Integrate formula (4-7) and formula (4-10), and add timestamps to the angle measurement, attitude and miss distance used:

[0156]

[0157] Among them, t 0 =t-Δt is the exposure time of the miss amount, Δt is generally obtained by prior estimation,

[0158] Rewriting formula (4-11) is:

[0159]

[0160] From formula (4-12), we can see that if we directly change t 0 Replace with t, then we have:

[0161]

[0162] From formulas (4-12) and (4-13), we can see that the interval [t 0 ,t] if there is Then the predicted miss distance vector Determined by the pitch angle, azimuth angle and attitude at the same time, and The relationship between them is:

[0163]

[0164] According to formulas (4-6) and (4-14), the predicted miss angle θ is calculated. Y ,θ X :

[0165]

[0166] Formula (4-15) is the predicted miss angle at the current moment.

[0167] Projection vector of miss distance under the carrier system With carrier height angle H s and azimuth A s Indicates that the servo control also uses the carrier altitude angle and azimuth angle to close the loop, then and The relationship between:

[0168]

[0169] from The carrier altitude angle and azimuth angle calculated in the calculation can be used for servo tracking closed loop:

[0170]

[0171] Formula (4-17) is the altitude angle and azimuth angle of the load system at the current moment after prediction.

[0172] S3, error calibration;

[0173] Error calibration is divided into time alignment of measurement data and space alignment of coordinate system and measurement data. Time alignment uses inertial navigation time (which can be internal time or GPS time) as a benchmark, and sends out photoelectric, radar and other measurement equipment at a fixed time through navigation messages. The reported measurement data is time-stamped, and the target positioning solution process uses time-aligned data as the data source for calculation and output;

[0174] The specific process of spatial alignment of the coordinate system and the measurement data is:

[0175] Step 1: Initial alignment of optoelectronics and inertial navigation using landmarks

[0176] Select a landmark, measure the latitude, longitude and elevation of the aiming point, and use the latitude, longitude and elevation of the optoelectronics to calculate the azimuth and elevation angle of the target relative to the optoelectronics, or directly measure its azimuth and elevation angle relative to the optoelectronics.

[0177] The optoelectronics work normally, measuring the carrier coordinate system azimuth and pitch angle of the target, while recording the inertial navigation direction and attitude information, converting the carrier coordinate system azimuth and pitch angle to the geographic coordinate system, and comparing them with the directly measured azimuth and pitch angle of the target to complete the optoelectronics zero position calibration.

[0178] Step 2: Precise alignment of optoelectronics and inertial navigation satellite measurement

[0179] With the help of visible light ephemeris, the azimuth and pitch angle of stars are calculated in real time using time and position information, optoelectronic guidance is implemented, and star tracking is performed using the visible light channel. The amount of miss-target tracking is recorded, the azimuth and pitch angle are measured, and the azimuth, pitch angle, inertial navigation heading, attitude and other information are calculated. The data of about 10 stars are continuously measured, with 20 sets of valid data for each star. According to the optoelectronic axis error model, the least squares method is used to calculate the optoelectronic axis error and complete the calibration process.

[0180] The model parameters and model obtained by calibration are embedded in the optoelectronic measurement program to correct the angle measurement data. At this time, the inertial navigation alignment error is not considered, and the optoelectronic measurement coordinate system is consistent with the inertial navigation carrier coordinate system.

[0181] S4, target tracking control;

[0182] Since the change in the altitude and azimuth of the target in the carrier system caused by the carrier's own angular motion can be detected by the inertial measurement unit (inertial sensor), the carrier operation information measured by the inertial measurement unit is the core information of tracking, and high-frequency inertial attitude multiplication and prediction as well as position loop update are the core of the design.

[0183] (1) Target vector acquisition

[0184] During the period between two target offset updates (the predicted update of the offset is also counted as an update), the target's altitude and azimuth in the geographic coordinate system are considered to remain unchanged. Therefore, the optical axis of the optoelectronic system needs to track the fixed geographic coordinate system. The algorithm flow is as follows:

[0185] After the offset (the vector of the target in the target coordinate system) is updated, the inertial navigation attitude information is converted to the geographic coordinate system according to the angle measurement information. The formula is as follows:

[0186] Among them, Rs is the target vector information on the target surface: R s =[xy 1] T , The target surface to carrier transformation matrix (right-hand system, corresponding to the positive and negative relationship of the angle measurement) is calculated using the inner ring angle measurement and the outer ring angle measurement:

[0187]

[0188] is the inertial navigation attitude matrix, which is calculated by the Euler angle provided by the inertial navigation. The formula is defined by the order and positive and negative of the inertial navigation Euler angle. The azimuth, pitch, and roll angles of the carrier based on the inertial space are measured by the inertial measurement unit and are ψ, θ, After three coordinate transformations from the inertial system to the carrier system, the coordinate system rotation relationship is as follows: Figure 2 shown.

[0189] The inertial system rotates around the Z axis by an angle of ψ, then around the Y axis by an angle of θ, and then around the Z axis Angle, the coordinate transformation matrix from the inertial system to the load system is:

[0190]

[0191] The output of the angular position compensation loop is the orientation of the inertial space of LOS as:

[0192]

[0193] Depend on Figure 3 As shown, let A' g If A' is a unit vector, g λe and λa are used to represent: λe is the pitch angle in the LOS inertial system, and λa is the azimuth angle in the LOS inertial system.

[0194] A' g =[cosλe sinλ a cosλe cosλ a sinλ e] T (6-5)

[0195] Then express A in the carrier system, and use the coordinate transformation matrix between the carrier system and the inertial system to get

[0196] Incident vector A b In the carrier coordinate system, it can be expressed as A b =[0 0 -1] T , then the ejection vector (LOS direction) under the carrier system can be obtained as:

[0197] A b '=[-sinαcosβ cosαcosβ sinβ] T (6-6)

[0198] From the above kinematic relationship, it can be inferred that the azimuth pitch angles α and β are given by the attitude matrix and the target inertia, that is, the kinematic relationship is defined:

[0199]

[0200] Where A' g =[cosλe sinλ a cosλe cosλ a sinλ e ] T The Euler angles given by the target inertia, A' g It is represented by λe and λa, and It can be obtained by θ, ψ, Indicates that when the gyro sensor detects the angular velocity ω of the carrier mx ,ω my ,ω mz , the real-time value of the quaternion is solved by the fourth-order RK method, so that the carrier attitude angle can be solved. From the perspective of control, the control quantities λe and λa are converted into the azimuth and pitch angles α and β of the optoelectronic turntable, among which α and β can be controlled by adjusting the torque motor voltage to achieve the change of the speed.

[0201] (2) Target vector update

[0202] After calculating the target's angular position in the geographic system according to the above steps, it is assumed that the target's geographic angular position remains unchanged before the offset is updated, and the angular position is continuously tracked. The specific process is as follows:

[0203] According to the real-time attitude information provided by the inertial navigation, the target geographic system vector calculated previously is converted to the carrier coordinate system:

[0204]

[0205] k means: the offset is updated for the kth time;

[0206] i means: after the offset is updated, the inertial navigation is updated for the i-th time;

[0207] Then, the target carrier system vector is used to obtain the azimuth and pitch loop control target angle, which is the position loop input.

[0208] (3) Target vector prediction

[0209] Combined with the characteristics of the inertial measurement unit, high-speed inertial information can be used to increase and predict the update frequency of the target vector position, further improving the frequency and accuracy of the position loop given quantity, and significantly improving the position loop data update rate (the specific value is related to the inertial information update rate, usually not less than 1000Hz).

[0210] The specific process is as follows:

[0211] 1000Hz gyro data is used to achieve 1000Hz high-frequency output and data prediction of attitude information.

[0212] In the absence of 1000Hz gyro data, it is necessary to use the inertial navigation's own attitude data for differential prediction (which will increase data noise) to predict and compensate for the phase delay of 10ms.

[0213] In the case of 1000Hz gyro data, although the gyro data has a lot of noise, it will basically not cause additional attitude errors due to the short prediction time, and can perform very accurate attitude prediction and frequency improvement. Since the gyro data is a small angle in a short time, the small angle formula is directly used for prediction.

[0214] The prediction formula is as follows:

[0215]

[0216] m means: update time scale of 200Hz gyro data (not required in system program);

[0217] 10 means: using 1000Hz gyro data, 10ms phase prediction can be performed;

[0218] The meaning of i is: the value of i is 1 to 5, indicating the 5 numbers interpolated in the 200Hz update. i is updated from 1 to 5 to realize the interpolation of 200Hz to 1000Hz attitude data.

[0219] The advantage of this prediction strategy is that it can give full play to the real-time characteristics of gyro data and meet the real-time requirements of servo stability control.

[0220] (4) Control process

[0221] The target indication data provided externally forms the control parameters and control instructions (guidance information) and is input into the control system;

[0222] The control system controls the detection head to turn to the target position (geographic system) according to the guidance information, forms the in-position state and reports it, and adjusts the sensor field of view to the position according to the target distance;

[0223] After the guidance turns into place, the target position and target pixel size information provided by the recognition system (internal or external recognition results) are sent to the control system, and the image tracking module of the control system guides the capture and tracking of the given target, and returns the miss distance and tracking status to the control system in real time;

[0224] The control system determines the tracking status. After the miss distance data is valid, the image tracking module of the control system enters the tracking closed loop and determines the tracking status in real time.

[0225] When the tracking status is normal, the control system controls the laser ranging and records the measurement data such as timestamp, hull attitude, angle measurement, miss distance, distance, etc. After measuring five sets of valid data continuously, the measurement is set to the measurement completion status, and the control system returns to the locked stable mode, waiting to enter the next target measurement process.

[0226] When the tracking state is abnormal, the control system switches back to the aiming mode and recaptures the tracking target through image guidance information. If the same target cannot be tracked for N consecutive cycles, the target is marked as unmeasurable, the control system switches to the locking stabilization mode, and reports the measurement result (unable to measure).

[0227] After a large number of experimental verifications, the target tracking can be within 20% overshoot when the miss delay is 300ms. Without changing the parameters, the adjustment time is reduced by 60%, and the stable accuracy is improved to 0.4mrd. When tracking targets in a small field of view, the peak miss value does not exceed 20 pixels, and the stable tracking adjustment time does not exceed 1s.

[0228] The present invention is not limited to what is described in the specification and implementation modes, and therefore additional advantages and modifications can be easily realized by those skilled in the art. Therefore, without departing from the spirit and scope of the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details, representative devices, and illustrative examples shown and described herein.

Claims

1. An optoelectronic tracking control method based on inertial information assistance, characterized in that: The steps include: S1, based on the inertial information-assisted optoelectronic target tracking coordinate system transformation, the projection vector of the target in the target surface system and the projection vector of the target in the geographic system are obtained; S2, target geographic system prediction, using inertial navigation as the reference to synchronize the miss distance and angle measurement, predict the projection vector under the geographic system, and obtain the altitude and azimuth of the load system at the current time; S3, error calibration, aligning the time of the measured data and the coordinate system with the space of the measured data, and correcting the angle measurement data; S4, target tracking control, uses the carrier operation information measured by the inertial measurement unit to increase and predict the target vector position update frequency, provides target indication data to form control parameters and guidance information, and controls the detection head to turn to the target position according to the guidance information. After the guidance is in place, it guides the capture and tracking of the given target and returns the miss distance and tracking status in real time.

2. The photoelectric tracking control method based on inertial information assistance according to claim 1, characterized in that: The specific process of step S1 is: the inertial measurement unit and the photoelectric measurement assembly are fixedly connected with the azimuth axis, and the pitch angle is θ, P XZ , P YZ are the unit target vectors In X L O L Z L and Y L O L Z L Projection, the coordinate systems are defined as follows: b L : Target surface coordinate system, Z L is the optical axis; b p : Pitch axis fixed coordinate system, and b L coincide; b p0 : Pitch axis zero position coordinate system, and b p Phase difference pitch angle θ; b v : Rotation axis coordinate system; b v0 : Angle measurement zero position coordinate system; b s : Installation base coordinate system, with b v0 overlap; b i :imu coordinate system; n: Department of Geography. The coordinate transformation process is as follows: (1)b p With b p0 The conversion relationship between them is: Among them, C X (θ) represents a rotation of θ along the X axis; (2)b v With b v0 The conversion relationship between them is: Rotary azimuth angle value θ v0 ,but: Among them, C Z (θ v0 ) represents a rotation along the Z axis θ v0 ; (3)b p With b L The conversion relationship between them is: (4) Projection vector of the target on the target surface The angle corresponding to the miss distance is θ X =∠P XZ O L P Z ,θ Y =∠P Z O L P YZ , the target unit vector is expressed as the miss distance, and θ is calculated based on the plane geometry P =∠P XZ O L P, and then use θ X and θ P express: in: tanθ P =tanθ Y cosθ X (4-5) (5) Target is b s Projection Substituting formula (4-7) into (4-1), (4-3) and (4-4) yields: Among them, the azimuth angle is clockwise, if the azimuth angle θ is defined z =-θ v0 , then the above formula (4-8) can be written as: (6) Projection vector in the target geographic system in, It is the installation base, i.e. the carrier posture matrix.

3. The photoelectric tracking control method based on inertial information assistance according to claim 1, characterized in that: The specific process of step S2 is: (1) Using the miss distance as a servo closed loop Integrate formula (4-7) and formula (4-10), and add timestamps to the angle measurement, attitude and miss distance used: Among them, t0=t-Δt is the exposure time of the miss amount, and Δt is generally obtained by prior estimation. Rewriting formula (4-11) is: From formula (4-12), we can see that if t0 is directly replaced by t, we have: From formulas (4-12) and (4-13), we can see that if there is Then the predicted miss distance vector Determined by the pitch angle, azimuth angle and attitude at the same time, and The relationship between them is: According to formulas (4-6) and (4-14), the predicted miss angle θ is calculated. Y ,θ X : Formula (4-15) is the predicted miss angle at the current moment. Projection vector of miss distance under the carrier system With carrier height angle H s and azimuth A s Indicates that the servo control also uses the carrier altitude angle and azimuth angle to close the loop, then and The relationship between: from The carrier altitude angle and azimuth angle calculated in the calculation can be used for servo tracking closed loop: Formula (4-17) is the altitude angle and azimuth angle of the load system at the current moment after prediction.

4. The photoelectric tracking control method based on inertial information assistance according to claim 1, characterized in that: The specific process of step S3 is as follows: error calibration is divided into time alignment of measurement data and space alignment of coordinate system and measurement data. Time alignment uses inertial navigation time as a reference, and uses navigation message timing to send out luminous, radar and other measurement equipment, and timestamps the reported measurement data. The target positioning solution process uses the time-aligned data as a data source for calculation and output; The specific process of spatial alignment of the coordinate system and the measurement data is: Step 1: Initial alignment of optoelectronics and inertial navigation using landmarks. Select a landmark, measure the latitude, longitude and elevation of the aiming point, and use the latitude, longitude and elevation of the optoelectronics to calculate the azimuth and elevation angle of the target relative to the optoelectronics, or directly measure its azimuth and elevation angle relative to the optoelectronics. The optoelectronics system works normally, measuring the carrier coordinate system azimuth and pitch angle of the target, and recording the inertial navigation direction and attitude information at the same time. The carrier coordinate system azimuth and pitch angle are converted to the geographic coordinate system, and compared with the directly measured azimuth and pitch angle of the target to complete the optoelectronics zero calibration; Step 2: Precise alignment of optoelectronics and inertial navigation satellite measurement. With the help of visible light ephemeris, the stellar azimuth and pitch angle are calculated in real time using time and position information, optoelectronic guidance is implemented, and star tracking is performed using the visible light channel. The tracking miss amount is recorded and the azimuth and pitch angle are measured. The azimuth, pitch angle, inertial navigation heading and attitude information are calculated, and multiple star data are continuously measured. Each star has multiple sets of valid data. According to the optoelectronic axis system error model, the least squares method is used to calculate the optoelectronic axis system error to complete the calibration process.

5. The photoelectric tracking control method based on inertial information assistance according to claim 1, characterized in that: The specific process of step S4 is: (1) Target vector acquisition, During the period between target offset updates, the target's altitude and azimuth in the geographic coordinate system remain unchanged. Therefore, the optical axis of the optoelectronic system needs to track the fixed geographic system direction. The algorithm flow is as follows: After the offset is updated, the inertial navigation attitude information is converted to the geographic coordinate system based on the angle measurement information. The formula is as follows: Among them, Rs is the target vector information on the target surface: R s =[xy 1] T , The target surface to carrier transformation matrix is ​​calculated using the inner ring angle measurement and the outer ring angle measurement: is the inertial navigation attitude matrix, which is calculated by the Euler angle provided by the inertial navigation. The formula is defined by the sequence and positive and negative of the inertial navigation Euler angle. The inertial measurement unit is used to measure the azimuth, pitch, and roll angles of the carrier based on the inertial space, which are ψ, θ, From the inertial system to the load system, after three coordinate transformations, The inertial system rotates around the Z axis by an angle of ψ, then around the Y axis by an angle of θ, and then around the Z axis Angle, the coordinate transformation matrix from the inertial system to the load system is: The output of the angular position compensation loop is the orientation of the inertial space of LOS as: Let A'g be a unit vector, then A'g can be expressed by λe and λa. λe is the pitch angle in the LOS inertial system, and λa is the azimuth angle in the LOS inertial system. A' g =[cosλe sinλ a cosλecosλ a sinλ e ] T (6-5) Then A' is expressed in the carrier system, and the coordinate transformation matrix between the carrier system and the inertial system is used to obtain Incident vector A b In the carrier coordinate system, it is represented as A b =[0 0 -1] T , then the ejection vector under the load system is: A b ’=[-sinαcosβ cosαcosβ sinβ] T (6-6) From the above kinematic relationship, it can be inferred that the azimuth pitch angles α and β are given by the attitude matrix and the target inertia, that is, the kinematic relationship is defined: Where A' g =[cosλesinλ a cosλecosλ a sinλ e ] T The Euler angles given by the target inertia, A' g It is represented by λe and λa, and By θ, ψ, Indicates that when the gyro sensor detects the angular velocity ω of the carrier mx ,ω my ,ω mz , the real-time value of the quaternion can be solved by the fourth-order RK method to obtain the carrier attitude angle. (2) Target vector update, According to the real-time attitude information provided by the inertial navigation, the target geographic system vector calculated previously is converted to the carrier coordinate system: k means: the offset is updated for the kth time; i means: after the offset is updated, the inertial navigation is updated for the i-th time; Then, the target carrier system vector is used to obtain the azimuth and pitch loop control target angle. (3) Target vector prediction, Use 1000Hz gyro data to achieve 1000Hz high-frequency output and data prediction of attitude information. The prediction formula is as follows: m means: update time scale of 200Hz gyro data; 10 means: use 1 1000Hz gyro data to perform 10ms phase prediction; The meaning of i is: the value of i is 1 to 5, indicating the 5 numbers interpolated in the 200Hz update. i is updated from 1 to 5 to realize the interpolation of 200Hz to 1000Hz attitude data. (4) Control process, Provide target indication data to form control parameters and control instructions to input into the control system; The control system controls the detection head to turn to the target position according to the guidance information, forms the in-position state and reports it, and adjusts the sensor field of view to the target distance at the same time; After the guidance and steering are in place, the target position and target pixel size information provided by the recognition system are sent to the control system. The image tracking module of the control system guides the capture and tracking of the given target, and returns the miss distance and tracking status to the control system in real time; The control system determines the tracking status. After the miss distance data is valid, the image tracking module of the control system enters the tracking closed loop and determines the tracking status in real time.

6. The photoelectric tracking control method based on inertial information assistance according to claim 1, characterized in that: When the tracking status is normal, the control system controls the laser ranging and records the measurement data such as timestamp, hull attitude, angle measurement, miss distance, distance, etc. After measuring five sets of valid data continuously, the measurement is set to the measurement completion status, and the control system returns to the locked stable mode, waiting to enter the next target measurement process; When the tracking status is abnormal, the control system switches back to the aiming mode and recaptures the tracking target through image guidance information. If the same target cannot be tracked for N consecutive cycles, the target is marked as unmeasurable, the control system switches to the locking stabilization mode, and reports the measurement results.

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