An evaluation index and calculation method for image motion compensation control effect

Abstract

The present invention relates to the cross-technical field of aviation optical imaging and motion control, and in particular to an evaluation index and a calculation method for image motion compensation control effect; firstly obtaining a theoretical first maximum compensation frequency and a first maximum compensation speed; then obtaining a second maximum compensation frequency and a second maximum compensation speed when an angle peak-to-peak value error within a uniform speed section of an image motion compensation instruction meets a preset condition; obtaining an evaluation index through a ratio of the two maximum compensation frequencies or a ratio of the two maximum compensation speeds; that is, converting the evaluation effect of image motion compensation into a line segment relationship that can be expressed as a percentage or visualized by a two-dimensional coordinate diagram, which can not only evaluate the control effect of image motion compensation, but also evaluate the ability of an image motion compensation control system, and can therefore be used to compare the compensation effects between different systems.

Description

Technical Field

[0001] The present invention belongs to the cross-technical field of aviation optical imaging and motion control, and in particular relates to an evaluation index and a calculation method for image motion compensation control effect. Background Art

[0002] Aero-optical imaging has the advantages of strong timeliness, high resolution and low cost, and has been widely used in many fields such as geographic surveying and mapping, resource exploration, environmental monitoring, emergency disaster reduction, national defense and security. However, due to factors such as the forward motion of the carrier aircraft and the scanning motion of the imaging payload, the imaging detector experiences relative motion during the exposure time, resulting in image blur and tailing. This phenomenon is called image shift. The image shift problem reduces the imaging resolution and even causes the loss of key information about the target morphology, affecting the overall interpretation and measurement of the image. Therefore, suitable actuators are needed to compensate for image shift, such as voice coil motors and piezoelectric ceramics.

[0003] At present, the evaluation method of the control effect of the image motion compensation system is mainly based on the error theory of automatic control, which calculates the angle or angular velocity error of the image motion compensation, and lacks the evaluation index of the image motion compensation system capability. Specifically, the input condition of the image motion compensation system is usually the compensation speed. and compensation cycle The traditional solution is to plan the compensation instructions according to the compensation speed and compensation period, and to make the angle error or angular velocity error of the image motion compensation meet certain requirements by designing a suitable controller or selecting suitable controller parameters. This method can only meet the requirements of the current image motion compensation control system, and it is impossible to reflect the specific image motion compensation capability of the system, and it is even more impossible to compare the image motion compensation capabilities of different systems horizontally. Summary of the invention

[0004] In view of the problems that the existing image motion compensation control effect evaluation is single and cannot directly reflect the ability of the image motion compensation control system, the present invention proposes an evaluation index and an evaluation method for the image motion compensation control effect; specifically, through a mathematical means, the evaluation effect of image motion compensation is creatively converted into a line segment relationship that can be expressed as a percentage and can also be visualized by a two-dimensional coordinate graph. It can not only evaluate the control effect of image motion compensation, but also evaluate the ability of the image motion compensation control system, and can therefore be used to compare the compensation effects between different systems.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The present invention provides a method for calculating an evaluation index of an image motion compensation control effect, the method comprising the steps of:

[0007] S1. Calculate the upper limit of the product of the compensation cycle and the compensation speed according to the stroke of the image motion compensation device; wherein the stroke of the image motion compensation device The motion angle greater than or equal to the image motion compensation ;

[0008] S2. Design the uniform speed period of image motion compensation according to the minimum exposure time of the imaging system, and then plan the maximum compensation period;

[0009] S3. Calculate the maximum compensation speed, generate a complete high-frequency and high-speed image motion compensation instruction, and record it as point M in the two-dimensional curve of compensation frequency and compensation speed;

[0010] S4. In the line segment from the origin O to M, different compensation frequencies and compensation speeds are selected, and the angle peak-to-peak error of the uniform speed segment is calculated under the control algorithm;

[0011] S5. Record the peak-to-peak angle error of the uniform speed segment to meet the T point closest to M, and use the compensation period and compensation speed of the T point to calculate the evaluation index of the image motion compensation control effect.

[0012] Furthermore, the motion angle E of image motion compensation is related to the image motion compensation frequency F and the compensation speed ω:

[0013] ;

[0014] in, represents a constant, ;

[0015] Assuming that the uniform acceleration and uniform deceleration in the speed compensation instruction are symmetrical, the compensated reciprocating motion angle is also symmetrical, then:

[0016] ;

[0017] It can be seen that the upper limit of the product of compensation period and compensation speed is .

[0018] Furthermore, the minimum exposure time of the imaging system , then the minimum image motion compensation cycle time is , then the theoretical maximum frequency of image motion compensation is:

[0019] .

[0020] Furthermore, in the two-dimensional coordinates, different points are selected from the origin O to point M, and the uniform speed segment is calculated under the control algorithm. Does the angle peak-to-peak error within the time satisfy:

[0021] ;

[0022] in, represents the peak-to-peak error, Indicates the angle command for a uniform speed period. Represents the actual angle data fed back by the sensor in the image motion compensation system, Indicates the angle error threshold.

[0023] Furthermore, the angular error does not exceed one pixel size, so choose , then:

[0024] ;

[0025] in, is the focal length of the imaging system, is the size of the imaging detector.

[0026] Further, from the origin To M point, the binary selection method is used to select the point, that is, if the Points of satisfaction ,but Click to select point and the midpoint of M, if the Points not satisfied ,but Click to select The midpoint between the point and the point closest to M that satisfies the conditions.

[0027] Furthermore, the maximum compensation frequency and maximum compensation speed T point where the angle peak-to-peak value of the uniform speed segment meets the conditions are found, and the index for evaluating the image motion compensation control effect of the imaging system is The definition is as follows:

[0028] .

[0029] Furthermore, according to the proportional relationship of triangles:

[0030] ;

[0031] in, and Indicates the maximum theoretical image motion compensation frequency and theoretical compensation speed, and It represents the maximum image motion compensation frequency and compensation speed that can be achieved to meet the error requirements. and The ratio represents the image motion compensation capability that can be achieved under the constraints of the imaging system.

[0032] The present invention also provides an evaluation index of image motion compensation control effect, and the evaluation index of image motion compensation control effect is calculated by the calculation method of the evaluation index of image motion compensation control effect of the present invention.

[0033] The present invention also provides a method for evaluating the image motion compensation control effect, and the method for evaluating the image motion compensation control effect is evaluated by the evaluation index of the image motion compensation control effect of the present invention.

[0034] Compared with the prior art, the invention can achieve the following beneficial effects:

[0035] At present, the traditional evaluation method usually plans instructions according to the needs, calculates the image motion compensation error under the instruction conditions, and checks whether the error requirements are met. If so, the controller design is completed. If not, the controller strategy or parameters are continuously modified until the error requirements are met. The present invention creatively uses a mathematical method to convert the evaluation effect of image motion compensation into a line segment relationship that can be expressed as a percentage or visualized by a two-dimensional coordinate graph. It can not only evaluate the control effect of image motion compensation, but also evaluate the capability of the image motion compensation control system, and can therefore be used to compare the compensation effects between different systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0037] Figure 1 A schematic diagram of a trapezoidal speed command curve for image motion compensation in a method for calculating an evaluation index of image motion compensation control effect provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram showing a mathematical curve for calculating an evaluation index of image motion compensation control effect in a method for calculating an evaluation index of image motion compensation control effect provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0044] Example 1

[0045] like Figure 1 As shown, a flow chart of a method for calculating an evaluation index of an image motion compensation control effect provided by an embodiment of the present invention is provided. It can be seen from the figure that the specific calculation steps of the evaluation index of the image motion compensation control effect of the present invention include:

[0046] S1. Calculate the upper limit of the product of the compensation cycle and the compensation speed according to the stroke of the image motion compensation device; the stroke of the image motion compensation device The motion angle must be greater than or equal to the image motion compensation angle. ,have:

[0047] (3);

[0048] The motion angle of the image motion compensation Image motion compensation frequency and compensation speed related:

[0049] (10);

[0050] in, represents a constant, .

[0051] Assuming that the uniform acceleration and uniform deceleration in the speed compensation instruction are symmetrical, the compensated reciprocating motion angle is also symmetrical, then:

[0052] (2)

[0053] It can be seen that the upper limit of the product of compensation period and compensation speed is .

[0054] The It is related to the planned speed instruction form, such as Figure 1 As shown in FIG. 1 , it is a schematic diagram of the trapezoidal speed instruction curve for image motion compensation in the implementation. It can be seen from the figure that according to the typical trapezoidal speed instruction, if the uniform acceleration and uniform deceleration time are equal and half of the uniform speed time, then .

[0055] S2. Design the uniform speed period of image motion compensation according to the minimum exposure time of the imaging system, and then plan the maximum compensation cycle; specifically, the minimum exposure time of the imaging system , then the minimum image motion compensation cycle time is , then the theoretical maximum frequency of image motion compensation is:

[0056] (11);

[0057] S3. Calculate the maximum compensation speed, generate a complete high-frequency and high-speed image motion compensation instruction, and record it as point M in the two-dimensional curve of compensation frequency and compensation speed; specifically, calculate the maximum image motion compensation speed ,like Figure 2 As shown, the mathematical curve for calculating the evaluation index of the image motion compensation control effect is a schematic diagram, and point M in the figure represents the point of maximum frequency and maximum speed of the image motion compensation.

[0058] S4. In the line segment from the origin O to M, different compensation frequencies and compensation speeds are selected, and the angle peak-to-peak error of the uniform speed segment is calculated under the control algorithm; specifically, in the two-dimensional coordinates, different points are selected from the origin O to M, and the angle peak-to-peak error of the uniform speed segment is calculated under the control algorithm. Does the angle peak-to-peak error within the time satisfy:

[0059] (6);

[0060] in, represents the peak-to-peak error, Indicates the angle command for a uniform speed period. represents the actual angle data fed back by the sensor in the image motion compensation system, where Indicates the angle error threshold. Generally, the angle error does not exceed one pixel size. , then:

[0061] (7);

[0062] in, is the focal length of the imaging system, is the size of the imaging detector.

[0063] Specifically, Figure 2 As shown, from the origin To point M, you can use the binary selection method to select points, that is, if the first If the points satisfy the condition, then Click to select point and the midpoint of M, if the If a point does not satisfy the condition, Click to select The midpoint between the point and the point closest to M that satisfies the conditions.

[0064] S5. The recording error satisfies the requirement that the point T is closest to M, and the compensation period and compensation speed of the point are used to calculate the evaluation index of the image motion compensation control effect proposed by the present invention; specifically, Figure 2 As shown in the figure, find the maximum compensation frequency and maximum compensation speed that meet the error conditions, that is, point T, and then evaluate the image motion compensation control effect of the system. The definition is as follows:

[0065] (12);

[0066] It is worth noting that the points that meet the conditions for image motion compensation are not completely on the line segment OM, and the frequency of image motion compensation may exceed Or the speed of image shift compensation exceeds However, the points on the OM line segment represent points with larger compensation speed and compensation frequency, and are also the line segments that best reflect the image motion compensation effect. Therefore, the calculation of the evaluation index of the system image motion compensation control effect described in the present invention is equivalent to finding point T on the line segment OM in the two-dimensional coordinates.

[0067] Further explanation: According to the proportional relationship of triangles:

[0068] (13)

[0069] in, and Indicates the theoretical maximum image motion compensation frequency and compensation speed, and It indicates the maximum image motion compensation frequency and compensation speed that can be achieved to meet the error requirements. The ratio of the two can indicate the image motion compensation capability that can be achieved under the constraints of the system. Due to the normalization effect of percentage, this index can also be used to compare the capabilities of different image motion compensation systems horizontally. Therefore, this index can be used as an evaluation index for image motion compensation.

[0070] The present invention creatively uses a mathematical method to convert the evaluation effect of image motion compensation into a line segment relationship that can be expressed as a percentage or visualized by a two-dimensional coordinate graph. It can not only evaluate the control effect of image motion compensation, but also evaluate the capability of the image motion compensation control system. Therefore, it can be used to compare the compensation effects between different systems.

[0071] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating an evaluation index of image motion compensation control effect, characterized in that: The calculation method comprises the steps of: S1. Calculate the upper limit of the product of the compensation cycle and the compensation speed according to the stroke of the image motion compensation device; wherein the stroke of the image motion compensation device The motion angle greater than or equal to the image motion compensation ; S2. Design the uniform speed period of image motion compensation according to the minimum exposure time of the imaging system, and then plan the maximum compensation period; S3. Calculate the maximum compensation speed, generate a complete high-frequency and high-speed image motion compensation instruction, and record it as point M in the two-dimensional curve of compensation frequency and compensation speed; S4. In the line segment from the origin O to M, different compensation frequencies and compensation speeds are selected, and the angle peak-to-peak error of the uniform speed segment is calculated under the control algorithm; S5. Record the peak-to-peak angle error of the uniform speed segment to meet the T point closest to M, and use the compensation period and compensation speed of the T point to calculate the evaluation index of the image motion compensation control effect; Find the maximum compensation frequency and maximum compensation speed T point where the angle peak-to-peak value of the uniform speed section meets the conditions, and then evaluate the image motion compensation control effect of the imaging system. The definition is as follows: ； According to the proportional relationship of triangles: ； in, and Indicates the maximum theoretical image motion compensation frequency and theoretical compensation speed, and It represents the maximum image motion compensation frequency and compensation speed that can be achieved to meet the error requirements. and The ratio represents the image motion compensation capability that can be achieved under the constraints of the imaging system.

2. The method for calculating the evaluation index of the image motion compensation control effect according to claim 1, characterized in that: The motion angle E of image motion compensation is related to the image motion compensation frequency F and the compensation speed ω: ； in, represents a constant, ; Assuming that the uniform acceleration and uniform deceleration in the speed compensation instruction are symmetrical, the compensated reciprocating motion angle is also symmetrical, then: ； It can be seen that the upper limit of the product of compensation period and compensation speed is .

3. The method for calculating the evaluation index of the image motion compensation control effect according to claim 1, characterized in that: Minimum exposure time of imaging system , then the minimum image motion compensation cycle time is , then the theoretical maximum frequency of image motion compensation is: 。 4. The method for calculating the evaluation index of the image motion compensation control effect according to claim 1, characterized in that: In the two-dimensional coordinate system, different points are selected from the origin O to M, and the uniform speed segment is calculated under the control algorithm. Does the angle peak-to-peak error within the time satisfy: ； in, represents the peak-to-peak error, Indicates the angle command for a uniform speed period. Represents the actual angle data fed back by the sensor in the image motion compensation system, Indicates the angle error threshold.

5. The method for calculating the evaluation index of the image motion compensation control effect according to claim 4, characterized in that: The angle error does not exceed one pixel size, select , then: ； in, is the focal length of the imaging system, is the size of the imaging detector.

6. The method for calculating the evaluation index of the image motion compensation control effect according to claim 5, characterized in that: From the origin To M point, the binary selection method is used to select the point, that is, if the Points of satisfaction ,but Click to select point and the midpoint of M, if the Points not satisfied ,but Click to select The midpoint between the point and the point closest to M that satisfies the conditions.

7. An evaluation index for image motion compensation control effect, characterized in that: The evaluation index of the image motion compensation control effect is calculated by the calculation method of the evaluation index of the image motion compensation control effect according to any one of claims 1 to 6.

8. A method for evaluating the effect of image motion compensation control, characterized in that: The method for evaluating the image motion compensation control effect is performed by using the evaluation index of the image motion compensation control effect described in claim 7.

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