Tracking control method not limited by mechanical zero position and load servo system

Abstract

The invention relates to the technical field of photoelectric load servo control, and particularly provides a tracking control method not limited by a mechanical zero position and a load servo system, and the method comprises the steps: calibrating the mechanical zero position of a frame, and carrying out the range interval conversion of a frame angular position instruction; and a to-be-rotated angle difference value is obtained through the converted target angular position instruction and the current frame angular position, range interval conversion is carried out on the angle difference value, and a load servo system is driven according to the converted angle difference value to realize # imgabs0 # continuous target tracking. The method is suitable for the photoelectric load which does not coincide with the mechanical zero position of the frame and the zero position of the encoder and requires the frame to realize # imgabs1 # continuous tracking control, is not limited by the mechanical zero position of the frame and is not influenced by the zero-crossing factor of the encoder, and the frame is driven to walk in the minimum stroke all the time.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic payload servo control, and in particular relates to a tracking control method and a payload servo system applicable to an optoelectronic payload frame that are not limited by the mechanical zero position. Background Art

[0002] Optoelectronic payloads have two-frame and three-frame structures according to different structures. To achieve rapid search and continuous tracking of a target, not only does the outermost frame need to be designed as an n×360° continuous rotation structure, but also the outermost frame servo control system needs to achieve closed-loop control of the frame position according to the minimum stroke to achieve continuous tracking of the target.

[0003] However, for an absolute encoder, which is often used as an angular position feedback element, its angular measurement range is 0°~360°. In the application of an n×360° continuous rotation electromechanical servo system, if the control algorithm is not effectively processed, when the electromechanical servo system performs closed-loop control of the position, the absolute value of the angular position error will be greater than 180°. At this time, the electromechanical servo system will achieve closed-loop control of the position in the direction greater than 180° according to the stroke. Especially near the zero position of the encoder, due to the objective existence of the steady-state error of the position servo system, there is a sudden change between 0° and 360° in the angular position measurement value, and the absolute value of the angular position error will also jump back and forth between greater than 180° and less than 180°, making it impossible to achieve continuous closed-loop control of any angular position command. In addition, it is impossible to ensure that the optical axis zero position (i.e., the mechanical zero position of the frame) of the optoelectronic payload completely coincides with the zero position of the encoder during the alignment process.

[0004] Therefore, there is an urgent need for a control method that can enable the optoelectronic payload frame to be unrestricted by the mechanical zero position, always perform closed-loop control of the position in the minimum stroke mode, and achieve continuous tracking of the target. Summary of the Invention

[0005] In view of this, the present invention aims to provide a tracking control method and a payload servo system that are not limited by the mechanical zero position. Without the need to align the mechanical zero position of the frame and the zero position of the encoder, the method can control the optoelectronic payload frame to perform tracking at any angle value. The payload servo system is not affected by the mechanical zero position of the frame and the encoder zero-crossing factor, and the frame always travels the minimum stroke to achieve continuous tracking control.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: On the one hand, the present invention provides a tracking control method that is not limited by the mechanical zero position, including: Determine the mechanical zero position of the frame , where the mechanical zero position of the frame represents the encoder measurement value when the optical axis points to the zero position; The target angle position command Convert to or within the interval; Calculate the frame angular position and transform to or Target angular position command within the range The difference , and the difference Convert to or Within the interval; the frame angle position represents the actual pointing angle of the optical visual axis; Based on conversion to or Difference within the interval The driving framework tracks the target.

[0007] Preferably, the encoder is an absolute encoder, and the encoder measurement value Range is .

[0008] Preferably, the frame mechanical zero position The range is .

[0009] Preferably, the frame angle position .

[0010] Preferably, the target angular position instruction Convert to or In the range, the target angle position command It can be any angle value. The conversion process includes: The target angle position command Convert to within the interval; Then convert to Target angular position command within the range Convert to or Within the range.

[0011] Preferably, the conversion to Target angular position command within the range Convert to The conversion rules within the interval are: like ,but ; like ,but ; like ,but ; will be converted to Target angular position command within the interval Convert to The conversion rule within the interval is as follows: If , then ; If , then ; If , then .

[0012] Preferably, , where is to convert to or Target angular position command within the interval , then or .

[0013] Preferably, the difference is converted to or within the interval.

[0014] Preferably, the difference or converted to within the interval is input to the position correction controller, and the correction controller realizes continuous tracking control of the frame by driving the motor .

[0015] On the other hand, the present invention provides a load servo system, which realizes continuous tracking control of the frame by using the above tracking control method that is not limited by the mechanical zero position .

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: The target angular position command of the control method of the present invention can be any value without upper and lower limits, and there is no need to align the mechanical zero position (i.e., the optical imaging optical axis zero position) and the encoder zero position before tracking control, and it can be applied to the scenario where the mechanical zero position of the frame does not coincide with the encoder zero position. For the input target angular position command, the target tracking process is not affected by the mechanical zero position of the frame and the encoder zero-crossing factor, and the frame always tracks the target from the minimum stroke, that is, the optoelectronic load frame always rotates in the direction where the stroke angle is less than 180°, until the actual angular position of the frame approaches the frame angular position command, so that the steady-state error of the frame angular position converges to the error band, that is, continuous tracking control is realized .

[0017] In addition, compared with the conventional control method with a limited target tracking range and a risk of target loss, the present invention can continuously track within the full space and full viewing angle range without the risk of losing the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not unduly limit the present invention. In the drawings: Figure 1 is a flowchart of a tracking control method without being limited by a mechanical zero position according to an embodiment of the present invention; Figure 2 is a flowchart of a recursive function program for converting a target angular position command according to an embodiment of the present invention to the interval; Figure 3 is a flowchart of a recursive function program for converting a difference according to an embodiment of the present invention to the interval; Figure 4 is a control schematic diagram of a tracking control method without being limited by a mechanical zero position according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many details are described to enable a better understanding of the present invention. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification to avoid the core part of the present invention being overwhelmed by excessive description. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0020] ​​It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other to form various implementation manners. At the same time, the steps or actions in the method description can also be reordered or adjusted in an obvious manner by those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0021] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 should not be construed as a limitation to 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 specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0023] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0024] Please refer to Figure 1 , in an embodiment of the present invention, there is provided a tracking control method that can be applied to an optoelectronic payload frame and is not limited by the mechanical zero position, especially applicable to an optoelectronic payload where the mechanical zero position of the frame does not coincide with the encoder zero position and the frame is required to achieve n×360° continuous tracking control, such that the input target angular position command is an arbitrary value, and the optoelectronic payload frame rotates towards the direction with a stroke less than 180°. The specific tracking control method includes the following steps: Step S1: First, it is necessary to accurately locate the mechanical zero position of the frame , providing an accurate reference for subsequent control operations. The mechanical zero position of the frame refers to the encoder measurement value corresponding to when the optical axis points to the zero position. Usually, in the laboratory, it is possible to complete the calibration of the optical axis zero position using metrological instruments such as optical tubes and theodolites, that is, to determine the value of the mechanical zero position of the frame .

[0025] The encoder in the optoelectronic payload servo control system is an absolute encoder, and the range of the absolute encoder is , that is, the range of the encoder measurement value is . As for the mechanical zero position of the frame , affected by factors such as the mechanical structure, installation method, and calibration process of the optoelectronic payload, it may be any value within , so the value range of the mechanical zero position of the frame is .

[0026] It can be seen from this that when the mechanical zero position of the frame does not coincide with the encoder zero position , the measurement value directly read by the encoder is not the true spatial mechanical angle of the frame, and there will be an angular difference with a value equal to between them. Therefore, the calculation formula for the frame angular position can be expressed as: ; Among them, the frame angular position represents the actual pointing angle of the current optical axis, .

[0027] Step S2: When performing target tracking, it is necessary to use the spatial angle of the target as the target angular position command and input it into the optoelectronic payload servo control system to drive the frame to rotate, so that the frame angular position approaches the target angular position command , that is, to make the optical axis point to the target to be tracked.

[0028] For the target angular position command , it can be any angular value without any upper or lower limits. Therefore, in the embodiment of the present invention, it is necessary to convert the target angular position command to the interval through a recursive function. The specific conversion process is a prior art means, for details, please refer to Figure 2 .

[0029] After converting the target angular position command to the interval, convert it to again or within the range. Specifically, convert to the target angular position command within the range convert to The conversion rule within the range is: If , then ; If , then ; If , then .

[0030] Convert the target angular position command to be converted to within the range convert to The conversion rule within the range is: If , then ; If , then ; If , then .

[0031] It should be noted that the principle of converting to and converting to is the same for the subsequent process, and the only difference lies in the representation of the boundary points, that is, representing the boundary points as or .

[0032] Step S3: The target angular position command that can be tracked has been obtained through the processing in Step S2 , therefore, it is necessary to further calculate the angle difference between the current frame angular position and the target angular position command . This angle difference is the angle by which the frame needs to rotate to track the target subsequently. Specifically, use the target angular position command that has been converted to or within the range obtained in Step S2 subtract the current frame angular position to obtain the angle difference , that is: ; wherein, has a value range of or . Similarly, the only difference between the above two value ranges lies in the representation of the boundary points.

[0033] Step S4: Obtain the angle difference After that, the difference is further converted through a recursive function to or within the interval. Similarly, the difference between the two intervals lies only in the representation of the boundary points. Specifically, taking the conversion of the difference to within the interval as an example, the specific process of conversion through the recursive function can be referred to Figure 3 .

[0034] Step S5: After the difference is converted to or within the interval, its driving framework can be used for target continuous tracking control. Specifically, the difference converted in step S4 to or within the interval is input into the position correction controller in the load servo system, and the correction controller realizes the continuous tracking control of the framework through the driving motor The above tracking control is applicable to the situation where the mechanical zero position of the framework and the zero position of the encoder do not coincide. In this way, any installation condition of the encoder can be applied, and the continuous tracking of the optoelectronic load framework is not restricted by the mechanical zero position of the framework. Similarly, the continuous tracking of the optoelectronic load framework is not affected by the encoder passing through zero.

[0035] Please refer to Figure 4 , this embodiment of the present invention also provides a load servo system, which obtains the angular difference for target tracking through the above steps S1 to S5 , and is input into the framework angular position correction controller of the load servo system. The framework angular position correction controller outputs the motor drive signal of the optoelectronic load according to the input . After power amplification, the motor drive signal is output to the actuator motor, and the actuator motor drives the framework load to perform target tracking.

[0036] Furthermore, in order to fully illustrate the superiority of this embodiment of the present invention, the tracking process is specifically described in detail with reference to Table 1 by way of example.

[0037] Table 1 Angular change process

[0038] Step S1: If the calibrated framework angular zero position is , which satisfies , and the measurement range of the absolute encoder is , then the framework angular position is ; Obviously, when the encoder passes through zero, the framework angular position is or , which specifically depends on the change in the measured value before and after the encoder passes through zero.

[0039] Step S2: Without loss of generality, take the frame angle position at the moment when the encoder passes through zero as the target angle position command , when the given target angle position command is , where n is an integer, convert the target angle position command according to Figure 2 the recursive algorithm shown into .

[0040] Step S3: Calculate the obtained frame angle error , which satisfies .

[0041] Due to the closed-loop control characteristics of the frame angle position servo system, there is a steady-state error band , where is a small positive real number. In fact, the encoder measurement value will jump between 0° and 360°, that is, the encoder value is and .

[0042] Therefore, the traditional tracking control method has the following problems: If no effective treatment is carried out, when the encoder measurement value is within , the corresponding frame angle position is within , the frame angle difference is within , the frame angle difference is a small quantity. Obviously , the servo control system can make the frame angle error tend to zero according to the minimum stroke. However, when the encoder value is within , the corresponding frame angle position is within , the frame angle error is within . At this time, the servo control system considers the difference to be a very large quantity. Obviously . In order to eliminate the error, the servo system will drive the frame angle to approach the target angle position command in a large circle in the direction greater than . During the tracking process, the error will exceed the error band. When the optoelectronic payload is tracking a target, if the tracking target is exactly near the frame angle position , the situation of losing the target will inevitably occur.

[0043] Advantages of the method of the present invention: If the tracking control method provided by the embodiment of the present invention that is not limited by the mechanical zero position is adopted, when the encoder measurement value is within the range of , the corresponding frame angular position is within the range of, the frame angular error is within , the frame angular error is a small quantity. Obviously , the servo control system can make the frame angular error tend to zero according to the minimum stroke. And when the encoder value is within the range of, the corresponding frame angular position is within the range of, the frame angular error is within the range. At this time, the embodiment of the present invention converts the difference or after conversion to the interval of , the frame angular difference is converted to within the range of, the frame angular difference is still a small quantity and satisfies , the servo control system can make the frame angular error tend to zero according to the minimum stroke. When the optoelectronic load tracks the target, even if the tracking target is exactly near the frame command angular position , continuous tracking of the target can still be achieved.

[0044] As can be seen from the above, the tracking control method provided by the embodiment of the present invention that is not limited by the mechanical zero position, while not being affected by the frame mechanical zero position limitation and the encoder zero-crossing factor, the frame always rotates in the direction of the minimum stroke to track the target, and the problem of target loss will not occur.

[0045] In short, the above is only a preferred embodiment of this specification, and is not intended to limit the protection scope of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included in the protection scope of this specification.

[0046] ​The systems, devices, modules or units described in one or more of the above embodiments may be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0047] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, commodity or device comprising a series of elements not only includes those elements but also other elements not expressly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, commodity or device comprising the element.

[0048] Each embodiment in this specification is described in a progressive manner, and the same or similar parts among the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiment.

[0049] The specific embodiments of this specification have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A tracking control method without being restricted by a mechanical zero position, characterized in that, Comprising: Determine the mechanical zero position of the frame , where the mechanical zero position of the frame represents the encoder measurement value when the optical axis of sight points to the zero position; Convert the target corner position command to or range; Calculate the difference between the frame corner position and the target corner position command within or the interval, and convert the difference to within , and convert the difference to within or the interval; the frame corner position represents the actual pointing angle of the optical axis of view. According to the difference within the conversion to or the difference within the interval Drive the framework to track the target.

2. The tracking control method without mechanical zero position limitation according to claim 1, wherein The encoder is an absolute encoder, and the encoder measurement value range is .

3. The tracking control method without mechanical zero position limitation according to claim 1, characterized in that The mechanical zero position of the frame ranges from .

4. The tracking control method without mechanical zero position limitation according to claim 1, characterized in that The frame corner position .

5. The tracking control method without mechanical zero position limitation according to claim 1, characterized in that, The target angular position command is converted to or within the range, where the target angular position command can be any angular value, and the conversion process includes: Convert the target angular position command to within the range; Then convert to the target angular position command within Convert to Or within the range.

6. The tracking control method without mechanical zero position limitation according to claim 5, characterized in that The target angular position command to be converted to within the range is converted to The conversion rule within the range is: If , then ; If , then ; If , then ; The target angular position command to be converted to within the range is converted to The conversion rule within the range is: If , then ; If , then ; If , then .

7. The tracking control method without mechanical zero position limitation according to claim 4, characterized in that , where is the target angular position command converted to or the interval , then or .

8. The tracking control method without mechanical zero position limitation according to claim 1, characterized in that Convert the difference through a recursive function to or within the range.

9. The tracking control method without mechanical zero position limitation according to claim 1, characterized in that Convert to Or The difference within the range An input position correction controller, and the correction controller realizes the framework by driving a motor Continuous tracking control.

10. A load servo system, characterized in that, Implementing framework for the tracking control method without mechanical zero position limitation according to any one of claims 1 to 9 Continuous tracking control.

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