A recognition method for high-orbit space infrared camera control system

Abstract

The application discloses a kind of identification methods for high orbit space infrared camera control system, comprising: establishing the equivalent direct current motor model under ideal frictionless condition;Establishing speed position double closed loop control system;Determine the system balance working point;Design balance point sweep input signal;Get boundary sweep signal;Obtain angle output signal;According to angle output signal, the control object balance point nominal model g ture And boundary model g 边界 Is obtained by identification fitting;Design PID control rate C s , evaluation C s The reliability of high orbit space infrared camera control system in orbit control under nominal model and the robustness of high orbit space infrared camera control system in orbit control under boundary model.The application will be applied to space infrared camera spin-scan mechanism system model identification based on the coarse and fine combination of camera working balance point dynamic system model identification method, can improve the identification efficiency and accuracy of space spin-scan mechanism model, improve the stability and reliability of infrared camera overall control.

Description

Technical Field

[0001] This invention belongs to the field of space remote sensing payload mechanism control technology, and particularly relates to an identification method for a high-orbit space infrared camera control system. Background Technology

[0002] With the vigorous development of space activities in various countries, the demand for space remote sensing observation in fields such as land resources and meteorological mapping has been increasing in recent years. High-resolution, wide-swath imaging has become a major development trend for space remote sensing payloads. Currently, wide-swath high-resolution imaging mainly relies on on-board rotary scanning mechanisms to drive the movement of reflectors, thereby achieving linear array scanning or area array mosaic imaging. High-precision space mechanism rotary scanning control technology, especially precise and efficient rotary scanning mechanism model identification technology, has become one of the important capabilities that optical remote sensing payloads must possess.

[0003] Currently, for spatial rotary scanning camera models, the common approach is to use a multi-point frequency division model identification method. This method requires a certain amount of prior information about the model being identified and works well in control systems where the system model is fixed and the shaft friction is low. However, the shaft system of a spatial rotary scanning mechanism exhibits nonlinear friction, which is related to the scanning speed and difficult to model accurately. Using a single-point frequency division model identification method in such cases would be complex, time-consuming, and have low accuracy.

[0004] During launch, the camera experiences harsh mechanical conditions, and the system model after normal operation in orbit differs from the ground-based model. Existing identification methods for space camera control systems, due to limitations in experimental and testing means, can only be used for identification in a ground environment. They cannot establish the envelope and boundary of the camera's on-orbit identification model, thus failing to fully simulate the camera's on-orbit state and affecting the robustness and reliability of on-orbit camera control. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide an identification method for the control system of a high-orbit space infrared camera. The method applies a coarse-fine dynamic system model identification method based on the camera's working equilibrium point to the identification of the space infrared camera's rotary scanning mechanism system model, which can improve the identification efficiency and accuracy of the space rotary scanning mechanism model and enhance the stability and reliability of the overall control of the infrared camera.

[0006] To address the aforementioned technical problems, this invention discloses an identification method for a high-orbit space infrared camera control system, comprising:

[0007] An equivalent DC motor model under ideal frictionless conditions is established for the control system of the uniform-speed rotary scanning mechanism of a space infrared camera.

[0008] For the equivalent DC motor model, a speed and position dual closed-loop control system is established; the PID controller is used to adjust the first-level closed-loop control parameters of the speed and position dual closed-loop control system to complete the coarse speed regulation control within ±10% near the uniform speed scanning operating point and determine the system's equilibrium operating point.

[0009] Based on the determined system equilibrium operating point, design the equilibrium point sweep frequency input signal;

[0010] Based on the working range of the frequency sweeping object, the frequency sweeping input signal at the equilibrium point is increased to obtain the boundary frequency sweeping signal;

[0011] The balance point sweep frequency input signal and the boundary sweep frequency signal are input to the hardware control drive circuit to drive the motor to rotate and obtain the angle output signal.

[0012] Based on the angle output signal, the nominal model g of the equilibrium point of the controlled object is obtained through identification and fitting. ture and boundary model g 边界 ;

[0013] Based on the nominal model for g ture Design the PID control rate C of the speed-position dual closed-loop control system. s Evaluation C s Reliability of on-orbit control of high-orbit space infrared camera control system under nominal model;

[0014] C s Substitute boundary model g 边界 Evaluation C s Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model.

[0015] In the aforementioned identification method for the control system of a high-orbit space infrared camera, a PID controller is used to adjust the first-level closed-loop control parameters of the speed-position dual-loop control system. This achieves coarse speed control within ±10% of the uniform scanning operating point, determining the system's equilibrium operating point. This includes: using a PID controller to perform coarse speed closed-loop control on the speed-position dual-loop control system, without requiring open-loop margin or closed-loop bandwidth, stabilizing the speed-position dual-loop control system, controlling the speed within ±10% of the nominal speed, and acquiring the digital control voltage u at this time. q The digital value of the control voltage collected over a period of time, u q average As the system's equilibrium operating point.

[0016] In the aforementioned identification method for the control system of a high-orbit space infrared camera, the balanced point sweep frequency input signal consists of three parts: a DC signal, a fixed-frequency sinusoidal signal, and a variable-frequency sinusoidal signal, specifically in the following form:

[0017]

[0018] Where in represents the balanced point sweep frequency input signal, Δu q This indicates the fluctuation range of the control voltage digital quantity within ±10% of the nominal speed, where ω0 represents the frequency of the fixed-frequency sinusoidal signal. t t1 represents the frequency of the variable frequency sinusoidal signal, t2 represents the duration of the DC signal, t3 represents the duration of the fixed frequency sinusoidal signal, and t3 represents the duration of the variable frequency sinusoidal signal.

[0019] In the above identification method for high-orbit space infrared camera control systems, the equilibrium point sweep frequency input signal is amplified according to the working range of the sweep frequency object to obtain the boundary sweep frequency signal, including:

[0020] Based on the operating range of the frequency sweeping object, the amplitude of the sinusoidal component of the equilibrium point frequency sweeping input signal in is increased by a times to obtain the boundary frequency sweeping signal in. * :

[0021]

[0022] In the aforementioned identification method for a high-orbit space infrared camera control system, the nominal model g of the control object's equilibrium point is obtained through identification and fitting based on the angle output signal. ture This includes: using the Matlab system identification toolbox to fit the nominal model g of the equilibrium point of the controlled object based on the angle output signal out corresponding to the frequency sweep input signal at the equilibrium point. ture .

[0023] In the aforementioned identification method for a high-orbit space infrared camera control system, the boundary model g is obtained through identification and fitting based on the angle output signal. 边界 This includes: outputting the angle signal 'out' based on the boundary frequency sweep signal. * The boundary model g was obtained by fitting using the Matlab System Identification Toolbox. 边界 .

[0024] In the aforementioned identification method for high-orbit space infrared camera control systems, the evaluation of C... s The reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model includes:

[0025] C s Substitute into the nominal model g ture The open-loop transfer function g is obtained. ture开环 ;

[0026] According to g ture开环 The open-loop phase stability margin γ and mode stability margin h are evaluated to assess C. sThe reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model is assessed; where, if the phase stability margin γ∈[35°, 45°] and the mode stability margin h≤1.5, then C is considered to be reliable. s The on-orbit control system of the high-orbit space infrared camera has good reliability under the nominal model.

[0027] In the aforementioned identification method for high-orbit space infrared camera control systems, C s Substitute boundary model g 边界 Evaluation C s Robustness of on-orbit control of the high-orbit space infrared camera control system under the boundary model includes:

[0028] C s Substitute boundary model g 边界 The open-loop transfer function g is obtained. s边界开环 ;

[0029] According to g s边界开环 Open-loop phase stability margin γ * Stability margin h * Evaluation C s Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model; where, if the phase stability margin γ * ∈[30°, 50°], and modulus stability margin h * If ≤1.78, then C is considered... s The high-orbit space infrared camera control system exhibits good robustness under the boundary model.

[0030] The present invention has the following advantages:

[0031] (1) This invention discloses an identification method for a high-orbit space infrared camera control system. It adopts a coarse-fine combined continuous dynamic frequency sweep method near the equilibrium point. Compared with the traditional single-point frequency sweep method, the identification time is shorter, the identification accuracy and frequency resolution are higher, and the identification efficiency can be effectively improved.

[0032] (2) This invention discloses an identification method for a high-orbit space infrared camera control system. It can establish the boundary model envelope of the control object that cannot be obtained by traditional methods according to the actual working conditions. It can evaluate the effect and stability of the on-orbit model control algorithm and provide model support for adjusting the parameters of the on-orbit control system after model changes, thereby improving the robustness and reliability of the on-orbit control system. Attached Figure Description

[0033] Figure 1 This is a flowchart of an identification method for a high-orbit space infrared camera control system according to an embodiment of the present invention;

[0034] Figure 2This is a schematic diagram of an equivalent DC motor model under an ideal frictionless condition in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of a speed and position dual closed-loop control system according to an embodiment of the present invention;

[0036] Figure 4 This is a u in an embodiment of the present invention. q Waveform diagram;

[0037] Figure 5 A block diagram of a speed loop control object system in an actual rotary sweeping mechanism identification example according to an embodiment of the present invention;

[0038] Figure 6 An open-loop transfer function g in an embodiment of the present invention s边界开环 The Bode plot. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] like Figure 1 In this embodiment, the identification method for the high-orbit space infrared camera control system includes:

[0041] Step 1: Establish an equivalent DC motor model under ideal frictionless conditions for the control system of the uniform-speed rotary scanning mechanism of the space infrared camera.

[0042] In this embodiment, for the control system of the uniform-speed rotary scanning mechanism of the space infrared camera, a system can be established based on prior knowledge, such as... Figure 2 The equivalent DC motor model shown is for the ideal frictionless condition. Wherein... Figure 2 In the middle, K t K represents the current torque coefficient. s The back electromotive force coefficient is represented by J, the moment of inertia of the motor and bearings is represented by L, the phase inductance is represented by R, and the phase resistance is represented by i. q Te represents the motor current, and ω represents the motor torque. r θ represents the rotational angular velocity, and θ represents the rotational angle.

[0043] Step 2: For the equivalent DC motor model, establish a speed and position dual closed-loop control system; use PID control to adjust the first-level closed-loop control parameters of the speed and position dual closed-loop control system to complete the coarse speed regulation control within ±10% near the uniform speed scanning operating point and determine the system's equilibrium operating point.

[0044] In this embodiment, for Figure 2 The equivalent DC motor model shown can be used to establish, for example... Figure 3The speed and position dual closed-loop control system is shown. In particular, in Figure 3 In the diagram, G1 represents the position loop PID controller, G2 represents the speed loop PID controller, and T... f To represent nonlinear friction in the shaft system, θ * Indicates the command angle. Indicates the commanded angular velocity.

[0045] Preferably, a PID controller can be used to perform a coarse speed closed-loop control on the speed-position dual closed-loop control system, without requiring open-loop margin or closed-loop bandwidth, thus stabilizing the speed-position dual closed-loop control system and controlling the speed within ±10% of the nominal speed. The digital control voltage u at this time is then collected. q ,like Figure 4 As shown; the digital value of the control voltage u collected over a period of time q average As the system's equilibrium operating point.

[0046] Step 3: Based on the determined system balance operating point, design the balance point sweep frequency input signal.

[0047] In this embodiment, since there is an acceleration phase during mechanism startup, the frequency sweep result is inaccurate during the acceleration phase. Therefore, a DC signal and a fixed-frequency sinusoidal signal are added before the frequency sweep. That is, the equilibrium point frequency sweep input signal consists of three parts, including a DC signal, a fixed-frequency sinusoidal signal, and a variable-frequency sinusoidal signal, specifically in the following form:

[0048]

[0049] Where in represents the balanced point sweep frequency input signal, Δu q This indicates the fluctuation range of the control voltage digital quantity within ±10% of the nominal speed, where ω0 represents the frequency of the fixed-frequency sinusoidal signal. t t1 represents the frequency of the variable frequency sinusoidal signal, t2 represents the duration of the DC signal, t3 represents the duration of the fixed frequency sinusoidal signal, and t3 represents the duration of the variable frequency sinusoidal signal.

[0050] Step 4: Based on the working range of the frequency sweeping object, increase the frequency sweeping input signal at the equilibrium point to obtain the boundary frequency sweeping signal.

[0051] In this embodiment, the amplitude of the sinusoidal component of the equilibrium point sweep frequency input signal in can be increased by a times, based on the working range of the sweep frequency object, to obtain the boundary sweep frequency signal in. * :

[0052]

[0053] Step 5: Input the balance point sweep frequency input signal and the boundary sweep frequency signal to the hardware control drive circuit to drive the motor to rotate and obtain the angle output signal.

[0054] In this embodiment, inputting the equilibrium point sweep frequency input signal to the hardware control and drive circuit yields the corresponding angle output signal 'out'; inputting the boundary sweep frequency signal to the hardware control and drive circuit yields the corresponding angle output signal 'out'. * .

[0055] Step 6: Based on the angle output signal, obtain the nominal model g of the equilibrium point of the controlled object through identification and fitting. ture and boundary model g 边界 .

[0056] In this embodiment, the nominal model g of the equilibrium point of the controlled object can be obtained by fitting the angle output signal out corresponding to the frequency sweep input signal at the equilibrium point using the Matlab system identification toolbox. ture The output signal OUT is based on the angle corresponding to the boundary frequency sweep signal. * The boundary model g was obtained by fitting using the Matlab System Identification Toolbox. 边界 .

[0057] Step 7, based on the nominal model in g ture Design the PID control rate C of the speed-position dual closed-loop control system. s Evaluation C s The reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model.

[0058] In this embodiment, C can be s Substitute into the nominal model g ture The open-loop transfer function g is obtained. ture开环 According to g ture开环 The open-loop phase stability margin γ and mode stability margin h are evaluated to assess C. s The reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model is assessed; where, if the phase stability margin γ∈[35°, 45°] and the mode stability margin h≤1.5, then C is considered to be reliable. s The on-orbit control system of the high-orbit space infrared camera has good reliability under the nominal model.

[0059] Step 8, place C s Substitute boundary model g 边界 Evaluation C s Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model.

[0060] In this embodiment, C can be s Substitute boundary model g边界 The open-loop transfer function g is obtained. s边界开环 According to g s边界开环 Open-loop phase stability margin γ * Stability margin h * Evaluation C s Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model; where, if the phase stability margin γ * ∈[30°, 50°], and modulus stability margin h * If ≤1.78, then C is considered... s The high-orbit space infrared camera control system exhibits good robustness under the boundary model.

[0061] Based on the above embodiments, the following is an explanation with reference to a specific example.

[0062] The identification method described in this invention mainly includes the following steps:

[0063] (1) Establish an equivalent DC motor model under ideal frictionless conditions.

[0064] For the rotation scanning axis system and motor control system of the space camera, the drive motor can be equivalent to... Figure 2 The equivalent DC motor model shown is for the ideal frictionless condition.

[0065] (2) Establish an equivalent DC motor model. Figure 3 The speed and position dual closed-loop control system is shown.

[0066] A PID controller is used to perform a coarse speed closed-loop control on the speed-position dual closed-loop control system. No requirements are placed on open-loop margin or closed-loop bandwidth, ensuring the stability of the speed-position dual closed-loop control system and maintaining the speed within ±10% of the nominal speed. The digital control voltage u at this time is then collected. q The digital value of the control voltage collected over a period of time, u q average As the system's equilibrium operating point.

[0067] (3) Design the balanced point sweep frequency input signal based on the system's balanced operating point.

[0068] The balanced point sweep frequency input signal in consists of three parts: a DC signal, a fixed-frequency sinusoidal signal, and a variable-frequency sinusoidal signal, specifically in the following form:

[0069]

[0070] (4) Determine the model fitting order and identify the nominal model of the equilibrium point of the controlled object obtained by fitting.

[0071] against Figure 2The equivalent DC motor model shown, based on design experience, assuming no nonlinear friction in the shaft system, has the following ideal model: Model. A digital input system that uses the equilibrium point sweep frequency input signal in as the voltage input, such as... Figure 5 As shown, 0.5 is the proportionality coefficient from the digital output of the control software to the actual output voltage of the voltage driver chip. The system outputs the angle signal 'out', and the nominal model g of the control object's equilibrium point is obtained by fitting using the Matlab system identification toolbox. ture .

[0072] (5) Single-point frequency sweep verification

[0073] To ensure g ture The fitting accuracy, after obtaining g ture Then, the results of continuous frequency sweep can be verified using the single-point frequency sweep method. The specific method is as follows:

[0074] Based on the system's operating frequency band, n representative frequencies are selected, and the input signal sequence is: in i (t)=in0+Asin(ω i t); Acquire and save the output signal, and calculate ω respectively. i The corresponding system amplitude gain and phase difference, and g ture Compare the two Bode plots; if the two are not significantly different, then g is considered to be... ture It is credible.

[0075] (6) Establish the boundary model envelope.

[0076] The amplitude of the sinusoidal component in the equilibrium point sweep frequency input signal in is increased to a times its original value (where a is a positive real number, selected according to the actual situation of the camera system), thus obtaining the boundary sweep frequency signal in. * :

[0077]

[0078] The boundary sweep frequency signal in * The input is sent to the hardware control and drive circuit, which drives the motor to rotate and obtains the angle output signal OUT. * The boundary model g was obtained by fitting using the Matlab System Identification Toolbox. 边界 .

[0079] (7) Design a dual closed-loop control law based on the nominal model.

[0080] Based on g ture Design the PID control rate C of the speed-position dual closed-loop control system. s .

[0081] Rating C sReliability of on-orbit control of high-orbit space infrared camera control system under nominal model: C s Substitute into the nominal model g ture The open-loop transfer function g is obtained. ture开环 According to g ture开环 The open-loop phase stability margin γ and mode stability margin h are evaluated to assess C. s The reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model is assessed; if the phase stability margin γ∈[35°, 45°] and the mode stability margin h≤1.5, then C is considered to be reliable. s The on-orbit control system of the high-orbit space infrared camera has good reliability under the nominal model.

[0082] (8) Evaluate robustness under boundary conditions

[0083] C s Substitute boundary model g 边界 The open-loop transfer function g is obtained. s边界开环 ,like Figure 6 As shown, according to g s边界开环 Open-loop phase stability margin γ * Stability margin h * Evaluation C s Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model; if phase stability margin γ * ∈[30°, 50°], and modulus stability margin h * If ≤1.78, then C is considered... s The high-orbit space infrared camera control system exhibits good robustness under the boundary model.

[0084] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0085] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. An identification method for a high-orbit space infrared camera control system, characterized in that, include: An equivalent DC motor model under ideal frictionless conditions is established for the control system of the uniform-speed rotary scanning mechanism of a space infrared camera. For the equivalent DC motor model, a speed and position dual closed-loop control system is established; the PID controller is used to adjust the first-level closed-loop control parameters of the speed and position dual closed-loop control system to complete the coarse speed regulation control within ±10% near the uniform speed scanning operating point and determine the system's equilibrium operating point. Based on the determined system equilibrium operating point, the equilibrium point sweep frequency input signal is designed; the equilibrium point sweep frequency input signal consists of three parts, including a DC signal, a fixed-frequency sine wave signal, and a variable-frequency sine wave signal, specifically in the following form: ···（1） in, This indicates the balanced point sweep frequency input signal. This indicates the fluctuation range of the control voltage digital value within ±10% of the nominal speed. Indicates the frequency of a fixed-frequency sinusoidal signal. Indicates the frequency of the variable frequency sinusoidal signal. Indicates the duration of the DC signal. Indicates the duration of a fixed-frequency sinusoidal signal. Indicates the duration of the frequency-converted sinusoidal signal; This represents the digital quantity of control voltage collected over a period of time. The average value; Based on the working range of the frequency sweeping object, the frequency sweeping input signal at the equilibrium point is increased to obtain the boundary frequency sweeping signal; The balance point sweep frequency input signal and the boundary sweep frequency signal are input to the hardware control drive circuit to drive the motor to rotate and obtain the angle output signal. Based on the angle output signal, the nominal model of the equilibrium point of the controlled object is obtained through identification and fitting. and boundary model ; Based on the nominal model Design the PID control rate of the speed-position dual closed-loop control system. ,evaluate Reliability of on-orbit control of high-orbit space infrared camera control system under nominal model; Will Substitute boundary model ,evaluate Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model.

2. The identification method for a high-orbit space infrared camera control system according to claim 1, characterized in that, A PID controller is used to adjust the first-stage closed-loop control parameters of the speed-position dual-loop control system, achieving coarse speed control within ±10% of the uniform speed scanning operating point. This determines the system's equilibrium operating point. The process includes: using a PID controller to perform coarse speed closed-loop control on the speed-position dual-loop control system, without specifying open-loop margin or closed-loop bandwidth, ensuring the stability of the speed-position dual-loop control system, controlling the speed within ±10% of the nominal speed, and acquiring the digital control voltage at this point. The digital control voltage collected over a period of time average As the system's equilibrium operating point.

3. The identification method for a high-orbit space infrared camera control system according to claim 2, characterized in that, Based on the operating range of the frequency sweeping object, the equilibrium point frequency sweeping input signal is amplified to obtain the boundary frequency sweeping signal, including: Based on the operating range of the frequency sweeping object, the balance point frequency sweeping input signal is... The amplitude of the sinusoidal component is increased to a times its original value, resulting in a boundary sweep frequency signal. : ···（2）。 4. The identification method for a high-orbit space infrared camera control system according to claim 1, characterized in that, Based on the angle output signal, the nominal model of the equilibrium point of the controlled object is obtained through identification and fitting. This includes: the angle output signal corresponding to the frequency sweep input signal based on the equilibrium point. The nominal model of the equilibrium point of the controlled object was obtained by fitting using the Matlab system identification toolbox. .

5. The identification method for a high-orbit space infrared camera control system according to claim 1, characterized in that, Based on the angle output signal, the boundary model is obtained through identification and fitting. This includes: outputting a signal based on the angle corresponding to the boundary frequency sweep signal. The boundary model was obtained by fitting using the Matlab System Identification Toolbox. .

6. The identification method for a high-orbit space infrared camera control system according to claim 1, characterized in that, evaluate The reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model includes: Will Substitute into the nominal model The open-loop transfer function is obtained. ; according to Open-loop phase stability margin Stability margin ,evaluate The reliability of on-orbit control of the high-orbit space infrared camera control system under the nominal model; where, if the phase stability margin... And the model stability margin Then it is believed The on-orbit control system of the high-orbit space infrared camera has good reliability under the nominal model.

7. The identification method for a high-orbit space infrared camera control system according to claim 1, characterized in that, Will Substitute boundary model ,evaluate Robustness of on-orbit control of the high-orbit space infrared camera control system under the boundary model includes: Will Substitute boundary model The open-loop transfer function is obtained. ; according to Open-loop phase stability margin Stability margin ,evaluate Robustness of on-orbit control of high-orbit space infrared camera control system under boundary model; where, if phase stability margin And the model stability margin Then it is believed The high-orbit space infrared camera control system exhibits good robustness under the boundary model.

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