Target tracking control method for rotary biprism

Abstract

The invention relates to a rotating biprism target tracking control method. The invention provides a control method for adjusting visual axis pointing based on a virtual axis angle error by analyzing propagation paths of a virtual pointing axis and a target visual axis in double Risley prisms and combining a visual axis adjustment rule of rotating the double prisms. The core of the method is that a coupling proportion controller is introduced, real-time stable tracking of a target is realized, and the problem of low tracking efficiency caused by direct use of image approximate equivalent information is avoided. Example results show that in dynamic target tracking, the method provided by the invention can track a moving target with a wide range of speeds. Compared with an existing tracking control method, the tracking precision and stability of the rotating biprism system on the moving target are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic tracking, and more particularly to a method for controlling the tracking of a rotating double prism target. Background Art

[0002] In the field of optoelectronic tracking technology, gimbal or fast steering mirror is usually used as the actuator for target tracking in the prior art. The gimbal can achieve large-angle deflection and is suitable for tracking large-range moving targets. However, its structure is complex, volume is large, and inertia is large, resulting in a slow dynamic response speed, difficult to meet the precise tracking requirements of high-speed moving targets, and high power consumption. The fast steering mirror has the advantages of fast response speed and high tracking accuracy, and can achieve fine adjustment of micro-radians. However, its deflection angle is small, and it is usually only suitable for tracking small-range targets and difficult to meet the requirements of large-range moving targets. Therefore, both the gimbal and the fast steering mirror in the prior art have limitations and cannot meet the target tracking requirements of large range, high precision, and fast response at the same time.

[0003] Compared with the gimbal and fast steering mirror mechanisms, the rotating double prism has the following characteristics: compact structure, high precision, insensitive to vibration, low cost, etc., and has certain advantages as a target tracking mechanism. The azimuth angle and deflection angle of the outgoing light beam after passing through the prism refraction are coordinated and controlled by two coaxially connected circular wedge prisms. When the rotating double prism is applied to optoelectronic tracking, the camera detector is used as the only source of target information, and its control target is the miss distance (pixel error of the target in the image). The premise for achieving stable and accurate tracking is to keep the miss distance stable and small enough.

[0004] The patent with the application number CN201310655695.2 proposes a method for controlling the tracking of a rotating double prism target based on a two-step method. However, this method requires repeated optimization iterations for each frame of feedback obtained, which will directly affect the real-time performance of the target tracking control. In order to achieve fast and accurate target pointing tracking control, a more efficient tracking control method needs to be proposed.

[0005] The existing technology (Yuan L, Li J, Huang Y, et al. High-precision closed-loop tracking of moving targets based on rotational double prisms [J]. Optical Engineering, 2021, 60 (11): 114107-114107.) proposed a real-time region selection closed-loop tracking method (RTSS), which inputs the error value feedback detector and outputs the adjustment value of the prism, and can continuously track the moving target for a period of time in the field of view of different areas. However, the target movement speed of the experimental setting is relatively low, and the control switching by judging different areas makes the algorithm more complicated. There is jitter during high-speed switching, which limits the application effect of the rotating double prism.

[0006] The prior art (Li J, Yuan L, Xia H, et al. Rotation matrix error-decoupling methods for Risley prism closed-loop tracking [J]. Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology, 2022, 76: 66-74.) proposes a rotation matrix error decoupling method (RMED), which claims to eliminate the coupling relationship between the x and y direction tracking errors and the prism rotation in the rotating dual prism tracking device on the image. Based on the decoupled image tracking error, the same direction and opposite rotations are simultaneously applied to the two prisms to adjust the visual axis to achieve closed-loop tracking. This method is essentially still coupling control, which only performs approximate equivalent calculations based on image errors, ignores the accurate correlation between image errors and deflection angles, and limits its tracking performance.

[0007] Existing target tracking methods based on rotating biprisms only perform an approximate equivalent processing of pointing errors based on image information and directly use it for target feedback, which limits the improvement of tracking performance. To overcome the shortcomings of existing technologies, we propose a new rotating biprism target tracking control method based on virtual axis angle error feedback to improve the tracking accuracy of the rotating biprism for high-speed motion. Summary of the Invention

[0008] The object of the present invention is to provide a rotating bi-prism target tracking control method, which can improve the tracking accuracy of the visual axis of the rotating bi-prism for a high-speed moving target.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] A method for controlling the target tracking of a rotating double prism, which is based on a rotating double prism target tracking system. The method includes the following steps: The CMOS camera receives image acquisition information and determines whether the current frame image contains the target to be tracked. If the target to be tracked is not included, the tracking system is placed in the scanning search mode. If the target to be tracked is included, the centroid pixel position of the target to be tracked is extracted, and based on this pixel position information and combined with the vector refraction law, a virtual path of the target visual axis in the rotating double prism system is constructed. In addition, a pointing visual axis path corresponding to the image center is constructed, the virtual axis angle error between the two visual axes is obtained, and it is described in two dimensions of azimuth angle error and deflection angle error. The embedded drive controller combines the visual axis adjustment law of the rotating double prism, and a coupling proportional controller is introduced into the control loop. After calculating the next rotation angle increment of the two prisms, the first prism and the second prism are driven to rotate to the corresponding angles, and the center of the target to be tracked is always maintained at the center of the camera field of view, realizing the target tracking control based on the rotating double prism;

[0011] The target tracking system based on the rotating double prism includes a CMOS camera for real-time collecting and extracting the position information of the target to be tracked in the image; an embedded drive controller for receiving image feedback information; a first motor and a second motor for driving the prism ∏1 and the prism Π2 to rotate; and an embedded drive controller for controlling the first motor and the second motor;

[0012] Both the prism Π1 and the prism Π2 can rotate independently around the Z W axis. The prism Π1 and the prism Π2 are arranged in series along the system optical axis, and the configuration of the refracting surface is flat-wedge-wedge-flat. The rotation angles are defined as θ1 and θ2, and the angular velocities are defined as ω1 and ω2. A right-angle coordinate system O C X C Y C Z C of the CMOS camera and a right-angle coordinate system O W X W Y W Z W are established, where the coordinate origins O C and O W are respectively located at the optical center of the CMOS camera lens and the center of the incident plane of the prism ∏1;

[0013] The method specifically includes the following steps:

[0014] Step S1: According to the pixel coordinates (Δp x , Δp y ) of the center of the target to be tracked, calculate the incident vector on the CMOS camera side And calculate the outgoing target line-of-sight vector based on the vector refraction law By the same principle, obtain the incident vector on the camera side with the pixel coordinates (0, 0) at the center of the image Furthermore, calculate the outgoing pointing line-of-sight vector

[0015]

[0016] Where: n0, n1, n2 are the refractive indices of air, prism 1, and prism 2, and n a , n b ∈[n0, n1, n2];

[0017] is the unit normal vector of the incident surface of prism 1

[0018] is the unit normal vector of the outgoing surface of prism 1

[0019] is the unit normal vector of the incident surface of prism 2

[0020] is the unit normal vector of the outgoing surface of prism 2

[0021] Where: θ1, θ2 are the prism rotation angles; α1, α2 are the prism apex angles

[0022] Step S2: Calculate the error between the two outgoing line-of-sight vectors, which is represented by the azimuth angle error projected on the Z-axis normal plane and the deflection angle error between the two line-of-sight vectors and the Z-axis respectively

[0023]

[0024]

[0025]

[0026] Step S3: If the center of the target to be tracked does not coincide with the center of the image, then the two outgoing line-of-sight vectors do not coincide and there is an error; calculate the azimuth angle error and the deflection angle error between the two line-of-sight vectors, and calculate the prism rotation angle increment based on the beam adjustment law; when the two prisms rotate at the same speed in the same direction, only the azimuth angle of the outgoing light is changed, and the deflection angle of the outgoing light is maintained unchanged; while when the two prisms rotate at the same speed in the opposite direction, only the deflection angle of the outgoing light is changed, and the azimuth angle is maintained unchanged

[0027] Step S4: Introduce a coupling ratio controller to independently calculate the rotation angles of the two prisms; when the deflection angle of the target line-of-sight vector needs to be reduced to coincide with the pointing line-of-sight vector, the angle between the main sections of the two prisms should increase. Therefore, the two prisms should rotate in the direction that increases the angle, and it is ensured that the rotation directions of the two prisms are opposite and the rotation angles are the same, which is Δρ; conversely, the angle between the main sections of the two prisms should decrease. Therefore, the two prisms should rotate in the direction that decreases the angle, and it is ensured that the rotation directions of the two prisms are opposite and the rotation angles are the same, which is Δρ

[0028] Step S5: When the azimuth angle of the target line-of-sight vector needs to be reduced to coincide with the pointing line-of-sight vector, the two prisms should ensure that the rotation directions of the two prisms are the same and the rotation angles are the same as both rotate in the direction that reduces the azimuth angle of the target line-of-sight vector; conversely, both prisms rotate in the direction that increases the azimuth angle of the target line-of-sight vector;

[0029] Step S6: In order to adjust the convergence effect of the line-of-sight error, multiply the deflection angle error by a proportionality coefficient k1 and multiply the azimuth angle error by a proportionality coefficient k2; combine the rotation angles required by the prisms in two dimensions to obtain the independent adjustment angles of the two prisms respectively;

[0030] Or

[0031] where k1 and k2 are constants. Different gain values of k1 and k2 will affect the convergence effect of the target tracking error. In the specific implementation process, continuously adjust k1 and k2 according to the tracking test results, and finally determine an optimal value;

[0032] Step S7: The embedded drive controller drives the first motor and the second motor based on the two prism angle adjustment commands Δθ1 and Δθ2 calculated in the above process, so as to drive the first prism and the second prism to rotate to the corresponding angles, so that the center of the CMOS camera field of view and the center of the target to be tracked always coincide;

[0033] The CMOS camera continuously detects the pixel position of the target center in the image. The embedded drive controller continuously calculates the rotation angles of the two prism drive motors based on the camera feedback information, and continuously drives the prisms to rotate to the corresponding angle positions. When the target center coincides with the image center, the two outgoing line-of-sight vectors will also coincide, so there is no line-of-sight error, and the rotation angles of the two prisms calculated according to the line-of-sight error are 0, and the prisms are no longer adjusted, and finally target tracking is achieved.

[0034] The beneficial effects of the present invention are:

[0035] In the rotational double prism target tracking method, virtual line-of-sight error is introduced instead of simply image error. The virtual line-of-sight error directly reflects the essence of target tracking error and combines with the line-of-sight adjustment law specific to the rotational double prism system. By introducing a coupled proportional controller, high-precision and stable target tracking is achieved.

[0036] Real-time tracking of high-speed moving targets is realized, and moving targets with different speeds and trajectories can be stably tracked. Compared with existing tracking methods, the tracking performance of the proposed method is improved and verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described in detail below with reference to the drawings and specific implementation methods.

[0038] Figure 1 is a schematic diagram of the rotational double prism system of the present invention for pointing and tracking;

[0039] Figure 2 is a control block diagram of the rotational double prism target tracking control method of the present invention;

[0040] Figure 3 is the moving trajectory of the horizontal and vertical trajectories and the diamond trajectory of the present invention;

[0041] Figure 4 is the tracking control flow of the rotational double prism target tracking control method of the present invention;

[0042] Figure 5 is the tracking error curve of the present invention, and the moving speed of the tracking target for the horizontal and vertical segmented trajectories is 2.13 mm / s;

[0043] Figure 6 is the tracking error curve of the present invention, and the moving speed of the tracking target for the diamond segmented trajectory is 3.01 mm / s;

[0044] Figure 7 is the tracking error curve of the present invention, and the moving speed of the tracking target for the horizontal and vertical segmented trajectories is 7.90 mm / s;

[0045] Figure 8 is the tracking error curve of the present invention, and the moving speed of the tracking target for the diamond segmented trajectory is 11.17 mm / s;

[0046] Figure 9 is the tracking error curve of the present invention, and the moving speed of the tracking target for the horizontal and vertical segmented trajectories is 23.7 mm / s;

[0047] Figure 10 is the tracking error curve of the present invention, and the moving speed of the tracking target for the diamond segmented trajectory is 33.52 mm / s. DETAILED DESCRIPTION OF THE INVENTION

[0048] The present invention will be further described in detail below with reference to the accompanying drawings.

[0049] As Figures 1 to 10 shown, in order to achieve the technical effect of "improving the line-of-sight tracking accuracy of the rotating double prism for high-speed moving targets", the steps and functions of a rotating double prism target tracking control method will be described in detail below;

[0050] A rotating double prism target tracking control method, which is based on a rotating double prism target tracking system, and the method includes the following steps: The CMOS camera receives image acquisition information, determines whether the current frame image contains the target to be tracked. If the target to be tracked is not included, the tracking system is placed in the scanning search mode. If the target to be tracked is included, the centroid pixel position of the target to be tracked is extracted, and based on this pixel position information, a virtual path of the target line of sight in the rotating double prism system is constructed in combination with the law of vector refraction; In addition, a line-of-sight path corresponding to the image center is constructed, the virtual axis angle error between the two lines of sight is obtained, and it is described in two dimensions of azimuth angle error and deflection angle error. The embedded drive controller combines the line-of-sight adjustment law of the rotating double prism, and introduces a coupling proportional controller in the control loop, calculates the next rotation angle increment of the two prisms, and drives the first prism and the second prism to rotate to the corresponding rotation angles, so as to always maintain the center of the target to be tracked at the center of the camera field of view, and realize the target tracking control based on the rotating double prism;

[0051] The rotating double prism-based target tracking system includes a CMOS camera for real-time collecting and extracting the position information of the target to be tracked in the image; an embedded drive controller for receiving image feedback information; a first motor and a second motor for driving the prism Π1 and the prism Π2 to rotate; and an embedded drive controller for controlling the first motor and the second motor;

[0052] Both the prism Π1 and the prism Π2 can rotate independently around the Z W axis. Among them, the prism Π1 is close to the CMOS camera, and the prism ∏2 is close to the target; the prism ∏1 and the prism ∏2 are arranged in series along the system optical axis, and the configuration of the refracting surface is flat-wedge-wedge-flat; the rotation angles are defined as θ1 and θ2, and the angular velocities are defined as ω1 and ω2;

[0053] As Figure 1 shown, a rectangular coordinate system O C X C Y C Z C of the CMOS camera and a world rectangular coordinate system O W X W Y W Z W are established, where the coordinate origins O C and O WAre respectively located at the optical center of the CMOS camera lens and the center of the incident plane of the prism ∏1; if the CMOS camera is well installed in the rotating double prism device, the camera optical axis Z C and the system optical axis Z W are theoretically coincident;

[0054] The principle of the rotating double prism target tracking control method based on the virtual axis angle error is as Figure 2 shown, and the corresponding flowchart is as Figure 4 shown;

[0055] This method specifically includes the following steps:

[0056] Step S1: According to the pixel coordinates (Δp x , Δp y ) of the center of the target to be tracked, calculate the incident vector on the CMOS camera side and calculate the outgoing target optical axis vector based on the vector refraction law By the same principle, the incident vector on the camera side is obtained with the pixel coordinates (0, 0) of the image center, and then the outgoing pointing optical axis vector

[0057]

[0058] where: n0, n1, n2 are the refractive indices of air, prism 1, and prism 2, n a , n b ∈[n0, n1, n2];

[0059] is the unit normal vector of the incident surface of prism 1,

[0060] is the unit normal vector of the outgoing surface of prism 1,

[0061] is the unit normal vector of the incident surface of prism 2,

[0062] is the unit normal vector of the outgoing surface of prism 2,

[0063] where: θ1, θ2 are the prism rotation angles; α1, α2 are the prism apex angles;

[0064] Step S2: Calculate the error between the two outgoing optical axis vectors, which is represented by the azimuth angle error projected on the Z-axis normal plane and the deflection angle error between the two optical axis vectors and the Z-axis respectively;

[0065]

[0066] Step S3: If the center of the target being tracked does not coincide with the center of the image, then the two outgoing optical axis vectors do not coincide and there is an error; calculate the azimuth error and deflection angle error between the two optical axes, and calculate the prism rotation angle increment based on the beam adjustment rule; when the two prisms rotate at the same speed and in the same direction, only the azimuth angle of the outgoing light is changed, and the deflection angle of the outgoing light is maintained unchanged; while when the two prisms rotate at the same speed and in opposite directions, only the deflection angle of the outgoing light is changed, and the azimuth angle is maintained unchanged.

[0067] Step S4: Introduce a coupling ratio controller to independently calculate the rotation angles of the two prisms; when the deflection angle of the target optical axis vector needs to be reduced to coincide with the pointing optical axis vector, the angle between the main sections of the two prisms should increase, so the two prisms should rotate in the direction that increases the angle, and ensure that the rotation directions of the two prisms are opposite and the rotation angles are the same as Δρ; conversely, the angle between the main sections of the two prisms should decrease, so the two prisms should rotate in the direction that decreases the angle, and ensure that the rotation directions of the two prisms are opposite and the rotation angles are the same as Δρ.

[0068] Step S5: When the azimuth angle of the target optical axis vector needs to be reduced to coincide with the pointing optical axis vector, the two prisms should ensure that the rotation directions of the two prisms are the same and the rotation angles are the same as Both rotate in the direction that reduces the azimuth angle of the target optical axis vector; conversely, both prisms rotate in the direction that increases the azimuth angle of the target optical axis vector.

[0069] Step S6: In order to adjust the convergence effect of the optical axis error, multiply the deflection angle error by a proportionality coefficient k1 and multiply the azimuth error by a proportionality coefficient k2; combine the required rotation angles of the prisms in two dimensions to obtain the independent adjustment angles of the two prisms respectively.

[0070] Or

[0071] where k1 and k2 are constants. Different gain values of k1 and k2 will affect the convergence effect of the target tracking error. In the specific implementation process, according to the tracking test results, continuously adjust k1 and k2 until an optimal value is finally determined; in this example, k1 = 0.8 and k2 = 1.2.

[0072] Step S7: The embedded drive controller drives the first motor and the second motor based on the two prism angle adjustment commands Δθ1 and Δθ2 calculated in the above process, so as to drive the first prism and the second prism to rotate to the corresponding angles, so that the center of the CMOS camera field of view always coincides with the center of the target to be tracked.

[0073] The CMOS camera continuously detects the position of the target center pixel in the image. The embedded drive controller continuously calculates the rotation angles of the two prism drive motors based on the feedback information from the camera, and continuously drives the prisms to rotate to the corresponding angular positions. When the target center coincides with the image center, the two outgoing optical axis vectors will also coincide, so there is no optical axis error. The rotation angles of the two prisms calculated based on the optical axis error are 0, and the prisms are no longer adjusted, finally achieving target tracking;

[0074] Next, the dynamic target is verified. When implementing dynamic target tracking and positioning, the actual simulated target moves along a certain trajectory at a certain speed. The rotating double prism target tracking system automatically controls the rotation of the two prisms according to the imaging feedback to change the optical axis of the camera, and moves the center of the CMOS camera's field of view to the target center;

[0075] The parameters involved in the embodiment are listed in Table 1. When implementing moving target tracking, the target is set to move at 6 different speeds, which are: 2.13 mm / s, 7.90 mm / s, 23.7 mm / s, 3.01 mm / s, 11.17 mm / s, 33.52 mm / s, corresponding to the maximum relative movement angular velocities of 0.59° / s, 2.20° / s, 6.59° / s, 0.84° / s, 3.10° / s, 9.24° / s respectively;

[0076] along two groups of multi-segment trajectories respectively: as Figure 3 shown, horizontal and vertical trajectories and diamond trajectories for movement. The tracking error is evaluated by the pixel distance between the target center and the image center in the image, defined as where Δp x and Δp y represent the pixel errors of the target imaging point and the image center in different directions; the root mean square error of the entire dynamic tracking process is used to evaluate the performance of the tracking system in target dynamic tracking; as Figures 5 to 10 shown, the tracking effects of this method are respectively;

[0077] Table 1 Parameters of the rotating double prism target tracking system

[0078]

[0079] Using the current prism angle state and target image feedback, the angular error between the pointing line-of-sight vector and the target line-of-sight vector is eliminated through closed-loop control, and the moving target is stabilized as much as possible in the area near the center of the image. First, the miss distance of the target in the image is obtained by using the target feature extraction algorithm. Then, the deflection angle error and azimuth angle error between the pointing axis and the target axis are determined by using the vector refraction law, and the independent adjustment amounts of the two prisms are calculated in combination with the line-of-sight adjustment law. Subsequently, a coupled proportional controller is introduced into the prism drive control loop to calculate and execute the relative rotation angle of each prism in real time, quickly eliminating the target tracking error;

[0080] The example results show that this method significantly improves the line-of-sight tracking accuracy of the rotating double prism for moving targets. For example, under the tracking control strategy VAAD based on virtual axis angle error feedback, the total root mean square (RMS) tracking errors of targets with relative angular velocities of 0.59° / s, 2.2° / s, 6.59° / s, 0.84° / s, 3.10° / s, and 9.24° / s are 1.18, 1.76, 6.43, 9.23, 23.19, and 32.78 pixels, respectively. Compared with the existing RTSS and RMED methods, this method has improvements in both the maximum error and root mean square error metrics, and the tracking performance is improved and verified.

Claims

1. A rotating dual-prism target tracking control method, based on a rotating dual-prism target tracking system, characterized in that: The method includes the following steps: The CMOS camera receives image acquisition information and determines whether the current frame image contains the target to be tracked. If it does not contain the target to be tracked, the tracking system is placed in the scanning search mode. If it contains the target to be tracked, the centroid pixel position of the target to be tracked is extracted, and based on this pixel position information and combined with the law of vector refraction, a virtual path of the target line of sight in the rotating double prism system is constructed. In addition, a pointing line of sight path corresponding to the image center is constructed, the virtual axis angle error between the two lines of sight is obtained, and it is described in two dimensions of azimuth angle error and deflection angle error. The embedded drive controller combines the line of sight adjustment law of the rotating double prism, and introduces a coupled proportional controller in the control loop, calculates the next rotation angle increment of the two prisms, and drives the first prism and the second prism to rotate to the corresponding angles, so as to always maintain the center of the target to be tracked at the center of the camera field of view, realizing the target tracking control based on the rotating double prism.

2. A rotary double prism target tracking control method according to claim 1, characterized in that: The target tracking system based on the rotating double prism includes a CMOS camera for real-time collecting and extracting the position information of the target to be tracked in the image; An embedded drive controller for receiving image feedback information; And a first motor and a second motor for driving the prism Π1 and the prism Π2 to rotate; and an embedded drive controller for controlling the first motor and the second motor.

3. The rotating bi-prism target tracking control method according to claim 2, characterized in that: Both the prism Π1 and the prism Π2 can rotate independently about the Z W axis. The prisms ∏1 and ∏2 are arranged serially along the optical axis of the system, and the configuration of the refracting surfaces is flat-wedge-wedge-flat. The rotation angles are defined as θ1 and θ2, and the angular velocities are defined as ω1 and ω2. A rectangular coordinate system O C X C Y C Z C is established for the CMOS camera and a world rectangular coordinate system O W X W Y W Z W , where the coordinate origins O C and O W are located at the optical center of the CMOS camera lens and the center of the incident plane of the prism ∏1, respectively.

4. The rotating bi-prism target tracking control method according to claim 3, characterized in that: This method specifically includes the following steps: Step S1: According to the pixel coordinates of the center of the target to be tracked (Δp x ,Δp y ), calculate the incident vector on the CMOS camera side And calculate the outgoing target visual axis vector based on the law of vector refraction The same principle is used to obtain the incident vector on the camera side using the pixel coordinate (0,0) at the center of the image. Then calculate the outgoing pointing axis vector Step S2: Calculate the error between the two outgoing line-of-sight vectors, which is represented by two dimensions of the azimuth angle error projected on the Z-axis normal plane and the deflection angle error between the two line-of-sight vectors and the Z-axis respectively; Step S3: If the center of the target to be tracked does not coincide with the image center, then the two outgoing line-of-sight vectors do not coincide and there is an error; calculate the azimuth angle error and the deflection angle error between the two lines of sight, and calculate the prism rotation angle increment based on the beam adjustment law; Step S4: Introduce a coupled proportional controller to independently calculate the rotation angles of the two prisms; Step S5: When the azimuth angle of the target visual axis vector needs to be decreased to coincide with the pointing visual axis vector, the two prisms should ensure that the rotation directions of the two prisms are the same and the rotation angles are the same as both rotate in the direction of decreasing the azimuth angle of the target visual axis vector; conversely, both prisms rotate in the direction of increasing the azimuth angle of the target visual axis vector; Step S6: In order to adjust the convergence effect of the line-of-sight error, multiply the deflection angle error by a proportional coefficient k1, and multiply the azimuth angle error by a proportional coefficient k2; combine the required rotation angles of the prism in two dimensions to obtain the independent adjustment angles of the two prisms respectively; Step S7: The embedded drive controller drives the first motor and the second motor with the two prism angle adjustment commands Δθ1 and Δθ2 calculated based on the above process, so as to drive the first prism and the second prism to rotate to the corresponding angles, so that the center of the CMOS camera field of view always coincides with the center of the target to be tracked.

5. A rotational double prism target tracking control method according to claim 4, characterized in that: In the said step S1: Where: n0, n1, and n2 are the refractive indices of air, prism 1, and prism 2, and n a , n b ∈ [n0, n1, n2]; is the unit normal vector of the incident surface of the prism 1, is the unit normal vector of the exit surface of the prism 1, is the unit normal vector of the incident surface of the prism 2, is the unit normal vector of the exit surface of the prism 2, Where: θ1 and θ2 are the prism rotation angles; α1 and α2 are the prism apex angles.

6. A rotary double prism target tracking control method according to claim 4, characterized in that: In the said step S2:

7. A rotary double prism target tracking control method according to claim 4, characterized in that: In the said step S3: When the two prisms rotate at the same speed and in the same direction, only the azimuth angle of the outgoing light is changed, and the deflection angle of the outgoing light is maintained unchanged; while when the two prisms rotate at the same speed and in the opposite direction, only the deflection angle of the outgoing light is changed, and the azimuth angle is maintained unchanged.

8. The rotating bi-prism target tracking control method according to claim 4, characterized in that: In the step S4: when the deflection angle of the target visual axis vector needs to be reduced to coincide with the pointing visual axis vector, the angle between the main sections of the two prisms should be increased. Therefore, the two prisms should rotate in the direction of increasing the angle, and it is ensured that the rotation directions of the two prisms are opposite and the rotation angle is the same as Δρ; on the contrary, the angle between the main sections of the two prisms should be reduced. Therefore, the two prisms should rotate in the direction of reducing the angle, and it is ensured that the rotation directions of the two prisms are opposite and the rotation angle is the same as Δρ.

9. A method for controlling the target tracking of a rotating double prism according to claim 4, characterized in that: In the step S6: or where k1 and k2 are constants. Different gain k1 and k2 values will affect the convergence effect of the target tracking error. In the specific implementation process, according to the tracking test effect, k1 and k2 are continuously adjusted to finally determine an optimal value.

10. A rotary double prism target tracking control method according to claim 4, characterized in that: In the step S7: the CMOS camera continuously detects the position of the target center pixel in the image. The embedded drive controller continuously calculates the rotation angles of the driving motors of the two prisms based on the camera feedback information, and continuously drives the prisms to rotate to the corresponding angular positions. When the target center coincides with the image center, the two outgoing visual axis vectors will also coincide, so there is no visual axis error, and the rotation angles of the two prisms calculated according to the visual axis error are 0, and the prisms are no longer adjusted, and finally the target tracking is realized.

Images