A two-axis rotating platform capable of tracking and aligning three-dimensional space targets

Abstract

The invention discloses a two-axis rotating platform capable of tracking and aiming at a three-dimensional space target, positioning the target through a binocular camera fixed to a base, tracking and aiming the target through a monocular camera fixed to the rotating platform, and providing an error feedback equation. Based on the invention, a high-precision and low-cost precise aiming platform can be realized.

Description

Technical Field

[0001] The invention relates to the field of control, and in particular to a feedforward and feedback control of a two-axis platform capable of tracking and aligning a three-dimensional space target. Background Art

[0002] The positioning, tracking and alignment of objects in three-dimensional space are widely used in the military field, such as the close-range defense weapon system equipped on modern naval ships, which uses radar to locate and track approaching targets, and drives the medium-caliber guns that fire rapidly to rotate in azimuth after computer calculation, aiming at the tracked target and shooting it down. Another example is the fire control system of various modern direct-aiming artillery, which uses the optoelectronic system to track the target to be hit, and drives the artillery to aim at the target stably during the maneuvering of the platform until the fire control computer solves the firing parameters and fires. This technology is also used.

[0003] This technology is widely used in the military and has a large demand in the civilian field, but it cannot be popularized due to cost and volume. This technology includes three parts: platform modeling and parameter calibration; target detection, positioning and tracking; and driving a vector on a two-axis rotating platform to align with the target through feedforward and feedback control. We carefully studied each part of the technology, combined with the actual needs of civilians, and invented a new, inexpensive platform using innovative technology that can be popularized and applied to a large number of civilian needs.

[0004] For example, by applying this technology, the laser mosquito killing function can be realized.

[0005] 1. Train neural networks to identify targets such as mosquitoes;

[0006] 2. Train the neural network to recognize face targets;

[0007] 3. Install the laser transmitter on the aiming baseline;

[0008] 4. When the device finds a mosquito target of interest, it can locate and track it through the present invention, and emit laser to aim at the wings of the mosquito to burn and strike it;

[0009] 5. When the device recognizes a human face, the device can be paused to ensure that the laser does not hit vulnerable targets such as eyeballs. Summary of the invention

[0010] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a two-axis platform capable of tracking and aligning a three-dimensional space target.

[0011] The technical solution of the present invention is as follows: a two-axis platform capable of tracking and aligning a three-dimensional space target is provided, comprising the following components:

[0012] Component 1: a load-bearing base;

[0013] Component 2: a binocular camera fixed to component 1;

[0014] Component 3: A servo motor fixed to component 1, capable of driving a rotating shaft;

[0015] Component 4: A servo motor fixedly connected to the rotating shaft of component 3, which can rotate together with the rotating shaft of component 3 and can drive another rotating shaft perpendicular to the rotating shaft of component 3;

[0016] Component 5: A platform fixedly connected to the rotating shaft of component 4, which can rotate together with the rotating shaft of component 4;

[0017] Component 6: a camera fixedly connected to component 5;

[0018] Component 7: The aiming baseline fixedly connected to component 5. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a front view of the platform of the present invention.

[0020] Figure 2 It is a side view of the platform described in the present invention. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] See also Figure 1 , Figure 2 The present invention provides a two-axis rotating platform capable of tracking and aligning a three-dimensional space target, and its control principle is as follows:

[0023] Step 1: Identify the target through the binocular camera and calculate its coordinates M in the world coordinate system w , find the coordinates that can make the aiming baseline vector pass through M w The direction angle and pitch angle.

[0024] Step 2: Iterative solution through approximation method:

[0025] The analytical solution to this problem is relatively complex, but an accurate numerical solution can be obtained through approximation. The iterative process is as follows:

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032] Among them, ε is a small positive value that controls the approximation accuracy. The smaller ε is, the higher the accuracy is. Output of the rotation axis of the direction coordinate system in the world coordinate system; is the output of the rotation axis of the pitch coordinate system in the direction coordinate system; θ z(k+1) ,θ y(k+1) The required approaching heading and pitch angle of this wheel are shown in steps three and four for the specific solution process.

[0033] Step 3: Solve the heading angle θ z(k+1) :

[0034]

[0035] The solution with the larger value is the desired one.

[0036] Step 4: Solve for the pitch angle θ y(k+1) :

[0037]

[0038] You can solve any two rows in the above equation, and the results will be the same.

[0039] Step 5: Feedforward control:

[0040] We have the current coordinates of the target The target posture of the control platform can be calculated according to steps 2 to 4. At the same time, we know the current posture And the angular velocity of the two axes, the time t required to transform the current posture to the target posture can be calculated k During this period, the target moves to one step coordinate at the current speed Based on this, the two-step control angle θ of the control platform is calculated z(k+2) ,θ y(k+2) , the two-step control angle is the required feedforward control angle.

[0041] Step 6: Feedback control:

[0042] We use the measurement feedback from the aiming feedback camera to eliminate control errors. Then, according to formula (1.3) in the claim, it is converted into the world coordinate system and recorded as the measurement coordinate The expression contains is the z-axis coordinate of the target in the camera coordinate system, which can be calculated according to the following formula:

[0043]

[0044] We already have measured coordinates The measurement angle θ can be calculated according to steps 2 to 4 z(m) ,θ y(m) .

[0045] We know the target angle and the measured angle, and we can get the angle error:

[0046]

[0047] After obtaining the angle error, feedback control algorithms such as PID, H infinity, and sliding mode can be further used to calculate the control quantity, drive the aforementioned platform to rotate to eliminate the error, and achieve precise alignment.

[0048] In summary, the present invention locates the target through a binocular camera, aims at the target through a monocular camera, and drives a two-axis rotating platform to accurately align the aiming baseline with the target. On the basis of achieving precise aiming, the system cost is greatly reduced, the system body is reduced, and a foundation for wide application is laid.

[0049] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A two-axis rotating platform, characterized in that: Includes the following components: Component 1: a load-bearing base; Component 2: a binocular camera fixed to component 1; Component 3: A servo motor connected to component 1, which drives a rotating shaft; Component 4: A servo motor fixedly connected to the rotating shaft of component 3, which can rotate with the rotating shaft of component 3 and drive another rotating shaft perpendicular to the rotating shaft of component 3; Component 5: A platform fixed to the rotating shaft of component 4, which can rotate with the rotating shaft of component 4; Component 6: a camera fixedly connected to component 5; Component 7: The aiming baseline fixed to component 5; The angle between the two rotation axes of the aforementioned components 3 and 4 is designed to be close to 90 degrees, and the exact angle and the distance between the two axes are known through calibration; The aforementioned components 3 and 4 drive component 5 to rotate without affecting the relative position and posture of the aforementioned components 2 and 1; A mathematical model can be established for the platform: ； ； Wherein, the superscript w represents the world coordinate system, which is fixed to component 1; the superscript y represents the azimuth coordinate system, which is fixed to component 4; the superscript p represents the pitch coordinate system, which is fixed to component 5; is the output of the vector of component 7 in the pitch coordinate system; for Output converted to the world coordinate system; The next point in the pitch coordinate system Coordinates converted to the world coordinate system; The next point in the world coordinate system Convert the coordinates to the camera coordinate system; is the rotation matrix connecting the pitch coordinate system and the direction coordinate system; is the rotation matrix connecting the orientation coordinate system and the world coordinate system; The output of the distance vector between the origin of the azimuth coordinate system and the elevation coordinate system in the azimuth coordinate system; Output of the distance vector between the origin of the direction coordinate system and the origin of the world coordinate system in the world coordinate system.

2. The two-axis rotating platform according to claim 1, characterized in that: The binocular cameras are all optical imaging cameras; The binocular camera shoots the same object through two cameras with known positions and angles, and by determining a feature point, the position of the object in three-dimensional space can be obtained; If two feature points can be determined, the position of the object in three-dimensional space and its rotation around the axis formed by the two feature points can be obtained; if three or more non-collinear feature points can be determined, the position and rotation posture of the object can be uniquely determined; It also includes tracking and positioning equipment that can identify the target of interest through two images captured at the same time by a binocular camera, and determine and match corresponding feature points on the two images; The tracking and positioning device can filter and track the target according to the obtained motion state of the target, including the position and rotation posture in three-dimensional space, and is called tracking lock when the filtering covariance matrix converges.

3. The two-axis rotating platform according to claim 1, characterized in that: The camera is a monocular optical imaging camera; The camera is fixed to component 5 and can rotate around the azimuth axis and the pitch axis in the world coordinate system; The position and angle of the camera relative to the alignment platform coordinate system are known through calibration; The relationship between the pixel point in the aiming feedback camera and the three-dimensional position in the world coordinate system can be established: ； Wherein, the superscript c represents the camera coordinate system fixed to the component 6 and having the optical center of the component 6 as the coordinate origin, and the superscript g represents the pixel coordinate system of the camera of the component 6; The next point in the pixel coordinate system Convert the coordinates to the world coordinate system; is the z-axis distance from the point to the optical center of the camera; is the coordinate of the origin of the camera coordinate system in the pitch coordinate system; The rotation matrix connecting the camera coordinate system and the world coordinate system.

4. The two-axis rotating platform according to claim 3, characterized in that: Step 4.1, the target in the known world coordinate system The coordinates of the components 3 and 4 are obtained to determine the angles of rotation so that component 7 passes through ; In step 4.2, use component 6 to measure the target image and calculate the error angle, which is then integrated with the rotation angle calculated in step 4.1 to eliminate the error.

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