Follow-up and tracking decoupling method for space camera scanning control system

Abstract

The invention discloses a follow-up and tracking decoupling method for a space camera scanning control system. The method comprises the following steps: determining a control object; the control objects are three independent shafts which are not structurally coupled in the space camera scanning system; three three-phase gullet-free permanent magnet synchronous torque motors are used for respectively driving three shafts to perform continuous whole-circle rotary scanning motion according to a planned track, so that the three shafts meet set requirements, and decoupling of driving shaft tracking control and follow-up shaft synchronous control of a space camera multi-shaft scanning mechanism is realized while wide imaging is realized. The method aims at achieving decoupling of driving shaft tracking control and follow-up shaft synchronous control of the multi-axis scanning mechanism of the space camera, the influence of follow-up shaft control on a driving shaft can be isolated while the high-precision synchronization performance is guaranteed, the tracking performance and the synchronization performance of a system are decoupled, the system structure is simplified, and the research and development cost of products is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of space remote sensing observation, and in particular relates to a follow-up and tracking decoupling method for a space camera scanning control system. Background Art

[0002] With the vigorous development of space activities, the demand for space remote sensing observations in the fields of land resources, meteorological surveying and mapping has increased in recent years, and high-resolution and wide-width imaging has become a major development trend of space remote sensing payloads. At present, wide-width and high-resolution imaging mainly relies on scanning mechanisms to drive the movement of reflectors or mirrors, thereby realizing linear scanning or array stitching imaging. High-precision space mechanism scanning control technology, especially multi-axis synchronous high-precision scanning control technology, has become one of the important capabilities that optical remote sensing payloads must possess.

[0003] According to the medium connection mode between the driving sources, the multi-axis drive synchronization system can be divided into a rigid connection system, a flexible connection system, and a connectionless system. At present, the field of space camera synchronous scanning control mostly adopts a connectionless system, that is, the physical medium connection between the motors is removed. Through the overall control structure design and the modeling analysis of the motor and the controller, the feedback signals of each axis are integrated in the control system structure to realize multi-axis synchronous control. In the connectionless synchronous control system, there are many strategies for the architecture and algorithm design of the control system. Among them, there is no coupling between the motors of the same given control strategy, and all motors achieve consistent follow-up of the reference signal. This method has strong anti-interference ability, but poor synchronization performance. The control strategy combining intelligent control (such as sliding film variable structure control, fuzzy control, predictive control, etc.) with the same given control can improve the overall synchronization performance of the system by improving the tracking performance of a single motor, but the system structure is complex and the calculation amount is large, which is not suitable for engineering applications. The deviation coupling control strategy has good structural reliability, high coupling degree, and a large number of controllable motors. It is widely used, but there are problems such as complex compensation mechanism and limited synchronization performance. The improved deviation coupling control strategy simplifies the compensation link of the traditional deviation coupling control structure, decouples the synchronization performance and tracking performance of the system to a certain extent, and solves the problem of difficult synchronization adjustment of the traditional deviation coupling control structure. However, it is still not completely decoupled, and the adjustment of the following performance will affect the tracking effect of the active axis. Summary of the invention

[0004] The technology of the present invention solves the problem: Overcoming the shortcomings of the prior art, a method for decoupling follow-up and tracking of a space camera scanning control system is provided, aiming to achieve the decoupling of the active axis tracking control and the follow-up axis synchronization control of the multi-axis scanning mechanism of the space camera, while ensuring high-precision synchronization performance, it can isolate the influence of the follow-up axis control on the active axis, decouple the system tracking performance and synchronization performance, simplify the system structure, and reduce product research and development costs.

[0005] In order to solve the above technical problems, the present invention discloses a method for decoupling following and tracking of a space camera scanning control system, comprising:

[0006] Determine a control object; wherein the control object is: three independent axes in the space camera scanning system that are not coupled in structure;

[0007] Through three three-phase slotless permanent magnet synchronous torque motors, the three axes are driven to perform continuous full-circle rotation scanning motion according to the planned trajectory, so that the three axes meet the set requirements. While achieving wide-width imaging, the active axis tracking control and the follower axis synchronous control of the multi-axis scanning mechanism of the space camera are decoupled.

[0008] In the above-mentioned decoupling method of following and tracking of the space camera scanning control system, the three axes are: an active axis, a first following axis and a second following axis.

[0009] In the above-mentioned method for decoupling following and tracking of a space camera scanning control system, the space camera scanning system is divided into an imaging section and a non-imaging section according to the imaging process.

[0010] In the above-mentioned decoupling method of following and tracking of the space camera scanning control system, three three-phase slotless permanent magnet synchronous torque motors are used to drive the three axes to perform continuous full-circle rotation scanning motion according to the planned trajectory, so that the three axes meet the following set requirements: 1) the three axes perform uniform and synchronous scanning motion in the imaging segment, and the uniform scanning motion speeds of the three axes in the imaging segment are different; 2) the scanning angle ranges of the three axes in the imaging segment are different, that is, the starting angles and ending angles of the imaging segment of the three axes are different; 3) the imaging segment time of the three axes is the same, that is, the three axes enter the imaging segment at the same time, pass through the satellite sub-satellite point at the same time, leave the imaging segment at the same time, and the scanning period of the three axes is the same.

[0011] In the above-mentioned method for decoupling the following motion and tracking of the space camera scanning control system, the space camera scanning system is divided into three stages according to the working process:

[0012] Start-up phase: Each axis starts to accelerate from rest and reaches its respective imaging segment starting angle at the same time, and the speed when reaching its respective imaging segment starting angle is exactly the uniform scanning speed of each axis in the imaging segment;

[0013] Scanning phase: starting from the scanning starting position of each axis, the scanning cycle of each axis is the same, and the imaging segment is kept synchronized.

[0014] Stop phase: Each axis slowly decelerates from the current movement speed until the speed is reduced to 0.

[0015] The above-mentioned method for decoupling following and tracking of the space camera scanning control system also includes: planning the trajectory of each axis in the startup phase and the scanning phase to obtain the planned trajectory to meet the synchronization of scanning of each axis in the imaging segment.

[0016] In the above-mentioned method for decoupling the following and tracking of the space camera scanning control system, the trajectory of each axis in the startup phase is planned, including:

[0017] Assume that: in the acceleration section of the startup phase, each axis starts from speed 0 and performs uniform acceleration motion, and the acceleration time is T QJ ;but:

[0018] The acceleration of each axis during the acceleration phase of the startup phase is:

[0019]

[0020] in, represents the acceleration of axis i in the acceleration section, Indicates the uniform scanning motion speed of axis i; i = 1, 2, 3; i = 1, indicates the active axis; i = 2, indicates the first follower axis; i = 3, indicates the second follower axis;

[0021] The motion angle increment of each axis in the acceleration section during the startup phase is:

[0022]

[0023] in, Indicates that axis i is in the acceleration segment t A The angular increment of motion at time t A ∈[0,T QJ ];

[0024] Assume that: In the uniform speed section of the startup phase, each axis Maintain uniform motion, and the uniform motion time of each axis is T QY ;but:

[0025] The motion angle increment of each axis in the uniform speed section during the startup phase for:

[0026]

[0027] in, Indicates that axis i is in the uniform speed section t B The angular increment of motion at time t B ∈[0,T QY ];

[0028] According to the determined motion angle increment of each axis in the acceleration section of the startup phase and the motion angle increment of each axis in the uniform speed section of the startup phase, the motion angle increment curve of each axis in the startup phase is determined. for:

[0029]

[0030] in, represents the end angle of the imaging segment of axis i;

[0031] according to Determine the trajectory of each axis during the startup phase.

[0032] In the above-mentioned method for decoupling the following and tracking of the spatial camera scanning control system, the trajectory of each axis scanning phase is planned, including:

[0033] Assume that: During the scanning phase, the active axis starts from the imaging starting point. Make a full rotation at a uniform speed; then:

[0034] Angle increment curve of the active axis during the scanning phase for:

[0035]

[0036] Among them, t c represents the duration of the imaging segment;

[0037] according to Determine the trajectory of the active axis during the scanning phase.

[0038] Assume that: in the scanning phase, the first follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the first follower axis in the non-imaging segment includes five stages: uniform speed segment A1, acceleration segment B, uniform speed segment A2, deceleration segment C and uniform speed segment A3, and the time experienced is respectively and The uniform speeds of the uniform speed sections A1, A2, and A3 are the same, all of which are but:

[0039] Angular velocity curve of the first follower axis during the scanning phase for:

[0040]

[0041] in, represents the movement time of the first follower axis in the scanning phase, A 2 Indicates the maximum value of the acceleration change of the first follower shaft in the speed change section; m 2 Indicates the frequency of sinusoidal change of the speed of the first follower axis;

[0042] Angle increment curve of the first follower axis in the scanning phase for:

[0043]

[0044] according to and determining a trajectory of the first follower axis during a scanning phase;

[0045] Assume that: in the scanning phase, the second follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the second follower axis in the non-imaging segment includes five stages: uniform speed segment A'1, acceleration segment B', uniform speed segment A'2, deceleration segment C' and uniform speed segment A'3, and the time experienced is respectively and The uniform speeds of the uniform speed segments A'1, A'2 and A'3 are the same, all of which are but:

[0046] Angular velocity curve of the second follower axis during the scanning phase for:

[0047]

[0048] in, A represents the movement time of the second follower axis in the scanning phase. 3 Indicates the maximum value of the acceleration change of the second follower shaft in the speed change section; m 3 Indicates the frequency of sinusoidal change of the speed of the second follower axis;

[0049] Angle increment curve of the second follower axis in the scanning phase for:

[0050]

[0051] according to and Determine the trajectory of the second follower axis during the scanning phase.

[0052] In the above-mentioned method for decoupling the following and tracking of the space camera scanning control system,

[0053]

[0054] In the above-mentioned decoupling method of following and tracking of the space camera scanning control system, the three-phase slotless permanent magnet synchronous torque motor is equivalent to a DC motor, and the transfer function G(s) is expressed as follows:

[0055]

[0056] Where: L represents the equivalent inductance, R represents the equivalent resistance, K t Indicates the current torque coefficient, Ks represents the back electromotive force coefficient, J s is the motor moment of inertia, and s represents a complex variable.

[0057] The present invention has the following advantages:

[0058] (1) The present invention discloses a method for decoupling the following motion and tracking of a space camera scanning control system. Through reasonable trajectory planning, it realizes variable-speed synchronous scanning of three axes with the same period and different speeds, thus solving the trajectory planning problem of the multi-axis synchronous variable-speed scanning mechanism of the space camera.

[0059] (2) The present invention discloses a method for decoupling following and tracking of a space camera scanning control system, which adopts different control strategies in the imaging section and the non-imaging section: a single-axis independent control strategy is adopted in the non-imaging section to strictly track the command angle, thereby reducing the speed error and angle error of the three axes reaching the imaging starting position; a synchronous following control decoupling strategy is adopted in the imaging section to couple the motion performance of the following axis with the active axis, while the motion performance of the active axis is not coupled with the following axis, thereby eliminating the influence of the following axis control system on the active axis control, thereby ensuring the good synchronous following performance of the following axis with the active axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a schematic diagram of scanning angles of a space camera scanning system in an embodiment of the present invention;

[0061] Figure 2 is a schematic diagram of changes in angle and angular velocity during the startup phase of a space camera scanning system in an embodiment of the present invention;

[0062] Figure 3 This is a schematic diagram of changes in angle and angular velocity during the startup phase and the scanning phase of a space camera scanning system in an embodiment of the present invention;

[0063] Figure 4 is a control block diagram of an equivalent DC motor in an embodiment of the present invention;

[0064] Figure 5 It is a single-axis position-speed dual closed-loop control block diagram in an embodiment of the present invention;

[0065] Figure 6 It is a block diagram of a synchronous follow-up control decoupling control in an embodiment of the present invention;

[0066] Figure 7 It is a schematic diagram of synchronization error of a follower axis when using different control strategies in an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0068] One of the core ideas of the present invention is: in order to overcome the limited synchronization performance of the existing deviation coupling control strategy and the shortcomings of the coupling of tracking and following performance, the present invention proposes a following and tracking decoupling method for a space camera scanning control system. The method can eliminate the influence of the following axis interference on the main axis control performance, has good synchronization performance and high control accuracy, and can be applied to various types of multi-axis scanning mechanisms of space cameras. The specific implementation of the method described in the present invention is as follows: 1) The trajectory planning of the three-axis synchronous scanning system of the space camera in the startup phase adopts a scheme combining uniform acceleration motion and uniform speed motion to ensure that the three axes reach their respective specified imaging starting angles at their respective specified speeds at the end of the startup phase; 2) The trajectory planning of the three-axis synchronous scanning system of the space camera in the scanning phase adopts a scheme of uniform speed in the imaging segment, uniform speed in the non-imaging segment, then acceleration, then uniform speed, then deceleration, and finally uniform speed. The speed curve and angle of the acceleration and deceleration process are planned using a sine curve to ensure that at the end of the non-imaging segment, the three axes reach their respective specified imaging starting angles at their respective specified speeds at the same time; at the same time, it is ensured that there is no speed mutation during the non-imaging segment, thereby improving the control accuracy; 3) The non-imaging segment of the startup phase and the scanning phase of the three-axis synchronous scanning system of the space camera adopts a 3-axis independent dual closed-loop control architecture; the imaging segment of the scanning phase adopts a synchronous follow-up control decoupling algorithm to eliminate the influence of the follow-up axis control system on the active axis control, thereby ensuring good synchronous follow-up performance.

[0069] In this embodiment, the following motion and tracking decoupling method of the space camera scanning control system includes:

[0070] Step 1: Determine the control object.

[0071] In this embodiment, the control objects refer to: three independent axes in the space camera scanning system that are not coupled in structure, namely, the driving axis, the first follower axis and the second follower axis.

[0072] Step 2: Plan the trajectory of each axis during the startup phase and the scanning phase to obtain the planned trajectory to meet the synchronization of scanning of each axis in the imaging segment.

[0073] In this embodiment, the space camera scanning system is divided into three stages according to the working process:

[0074] Start-up phase: each axis starts to accelerate from rest and reaches its respective imaging segment starting angle at the same time, and the speed when reaching its respective imaging segment starting angle is exactly the uniform scanning speed of each axis in the imaging segment.

[0075] Scanning phase: starting from the scanning starting position of each axis, it rotates continuously for a full circle to keep the imaging segments synchronized and the scanning period of each axis the same.

[0076] Stop phase: Each axis slowly decelerates from the current movement speed until the speed is reduced to 0.

[0077] Preferably, the trajectory of each axis during the startup phase is planned in the following manner:

[0078] Assume that: in the acceleration section of the startup phase, each axis starts from speed 0 and performs uniform acceleration motion, and the acceleration time is T QJ ;but:

[0079] The acceleration of each axis during the acceleration phase of the startup phase is:

[0080]

[0081] in, represents the acceleration of axis i in the acceleration section, Indicates the uniform scanning motion speed of axis i; i=1, 2, 3; i=1, indicates the active axis; i=2, indicates the first follower axis; i=3, indicates the second follower axis.

[0082] The motion angle increment of each axis in the acceleration section during the startup phase is:

[0083]

[0084] in, Indicates that axis i is in the acceleration segment t A The angular increment of motion at time t A ∈[0,T QJ ].

[0085] Assume that: In the uniform speed section of the startup phase, each axis Maintain uniform motion, and the uniform motion time of each axis is T QY ;but:

[0086] The motion angle increment of each axis in the uniform speed section during the startup phase for:

[0087]

[0088] in, Indicates that axis i is in the uniform speed segment t B The angular increment of motion at time t B ∈[0,T QY ].

[0089] According to the determined motion angle increment of each axis in the acceleration section of the startup phase and the motion angle increment of each axis in the uniform speed section of the startup phase, the motion angle increment curve of each axis in the startup phase is determined. for:

[0090]

[0091] in, represents the end angle of the imaging segment of axis i.

[0092] according to Determine the trajectory of each axis during the startup phase.

[0093] Preferably, the trajectory of each axis scanning phase is planned in the following manner:

[0094] Assume that: During the scanning phase, the active axis starts from the imaging starting point. Make a full rotation at a uniform speed; then:

[0095] Angle increment curve of the active axis during the scanning phase for:

[0096]

[0097] Among them, t c Indicates the duration of the imaging segment.

[0098] according to Determine the trajectory of the active axis during the scanning phase.

[0099] Assume that: in the scanning phase, the first follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the first follower axis in the non-imaging segment includes five stages: uniform speed segment A1, acceleration segment B, uniform speed segment A2, deceleration segment C and uniform speed segment A3, and the time experienced is respectively and The uniform speeds of the uniform speed sections A1, A2, and A3 are the same, all of which are but:

[0100] Angular velocity curve of the first follower axis during the scanning phase for:

[0101]

[0102] in, represents the movement time of the first follower axis in the scanning phase, A 2 Indicates the maximum value of the acceleration change of the first follower shaft in the speed change section; m 2 Indicates the frequency of sinusoidal change of the speed of the first follower axis,

[0103] Angle increment curve of the first follower axis in the scanning phase for:

[0104]

[0105] according to and Determine the trajectory of the first follower axis during the scanning phase.

[0106] Assume that: in the scanning phase, the second follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the second follower axis in the non-imaging segment includes five stages: uniform speed segment A'1, acceleration segment B', uniform speed segment A'2, deceleration segment C' and uniform speed segment A'3, and the time experienced is respectively and The uniform speeds of the uniform speed segments A'1, A'2 and A'3 are the same, all of which are but:

[0107] Angular velocity curve of the second follower axis during the scanning phase for:

[0108]

[0109] in, A represents the movement time of the second follower axis in the scanning phase. 3 Indicates the maximum value of the acceleration change of the second follower shaft in the speed change section; m 3 Indicates the frequency of the sinusoidal change of the speed of the second follower axis,

[0110] Angle increment curve of the second follower axis in the scanning phase for:

[0111]

[0112] according to and Determine the trajectory of the second follower axis during the scanning phase.

[0113] Step 3: Use three three-phase slotless permanent magnet synchronous torque motors to drive the three axes to perform continuous full-circle rotation scanning motion according to the planned trajectory, so that the three axes meet the set requirements. While achieving wide-width imaging, the active axis tracking control of the multi-axis scanning mechanism of the space camera is decoupled from the synchronous control of the follower axis.

[0114] In this embodiment, the space camera scanning system is divided into an imaging section and a non-imaging section according to the imaging process. Three three-phase slotless permanent magnet synchronous torque motors are used to drive the three axes to perform continuous full-circle rotation scanning motion according to the planned trajectory. Figure 1As shown in the figure, in order to achieve wide-width imaging, the three axes are required to meet the following setting requirements: 1) the three axes perform uniform and synchronous scanning motion in the imaging segment, and the uniform scanning motion speeds of the three axes in the imaging segment are different; 2) the scanning angle ranges of the three axes in the imaging segment are different, that is, the starting angles and ending angles of the imaging segment of the three axes are different; 3) the imaging segment time of the three axes is the same, that is, the three axes enter the imaging segment at the same time, pass through the satellite sub-satellite point (0° position) at the same time, and leave the imaging segment at the same time, and the scanning period of the three axes is the same.

[0115] In this embodiment, the three axes are all driven by three-phase slotless permanent magnet synchronous torque motors. The three-phase slotless permanent magnet synchronous torque motor drive can be equivalent to a DC motor, such as Figure 4 As shown, its transfer function G(s) is expressed as follows:

[0116]

[0117] Where: L represents the equivalent inductance, R represents the equivalent resistance, K t Indicates the current torque coefficient, K s represents the back electromotive force coefficient, J s represents the motor's moment of inertia, and s represents a complex variable. Figure 4 in, u q Indicates the motor voltage, i q represents the motor current, T e Represents the motor output torque, ω τ represents the rotation speed of each axis, and θ represents the angle of each axis.

[0118] Furthermore, for the space camera scanning system in the space camera scanning system, the three-phase slotless permanent magnet synchronous torque motor drive adopts the following control strategy to drive the three axes to perform continuous full-circle rotation scanning motion according to the planned trajectory, and make the three axes meet the set requirements:

[0119] Startup phase:

[0120] Each axis adopts a single-axis position-speed dual closed-loop control algorithm, with no coupling between them. Each axis is controlled with the real-time angle command as the target. Among them, the control structure corresponding to the single-axis position-speed dual closed-loop control algorithm is as follows: Figure 5 As shown, its transfer function G 单 (s) means as follows:

[0121]

[0122] Among them, C1(s) represents the speed loop control rate transfer function of each axis, G1(s) represents the position loop control rate transfer function of each axis, and G(s) represents the equivalent transfer function of the DC motor. Indicates the trajectory planning angle command of each axis during the startup process, S i(t) is the measured angle of each axis during the startup process.

[0123] Scanning phase:

[0124] The active axis adopts a single-axis position and speed dual closed-loop control algorithm, and only tracks its own real-time angle command. The control structure is as follows: Figure 5 shown.

[0125] The follower axis adopts the synchronous follower control decoupling algorithm, and adjusts the drive amount of the follower axis according to the proportional difference between the follower axis and the active axis. The control structure is as follows Figure 6 As shown, its transfer function G 随 (s) means as follows:

[0126]

[0127] Among them, C2(s) represents the transfer function of the speed loop control rate of the follower axis, G2(s) represents the transfer function of the position loop control rate of the follower axis, and G(s) represents the equivalent transfer function of the DC motor. Indicates the active axis trajectory planning angle instruction during the scanning process, S j (t) represents the measured angle of the follower axis during the scanning process, k j Represents the angle scale factor.

[0128] The above algorithm can eliminate the influence of the follower axis control system on the active axis control and ensure good synchronous following performance.

[0129] Based on the above embodiment, a specific example is described below.

[0130] (1) Characteristics of the controlled object

[0131] There are three independent axes in the space camera scanning system that are not coupled in structure. Each axis is driven by three three-phase slotless permanent magnet synchronous torque motors to perform continuous full-circle rotation scanning motion. As mentioned above, the imaging segment angle ranges of the three axes are different, but the imaging segment time is required to be the same. In this case, the three axes have different uniform motion speeds in the imaging segment. The imaging segment ranges and scanning speeds of the three axes are shown in Table 1 below:

[0132]

[0133]

[0134] Table 1. Schematic diagram of three-axis imaging segment range and scanning speed

[0135] It can be seen that the active axis moves at a constant speed of 27° / s throughout the whole scanning process, and the first and second follower axes first accelerate and then decelerate in the non-imaging section. The performance requirement of this scanning system is that the angles of the three axes have good synchronization during the uniform motion of the imaging section, and there is no special requirement for the performance of the non-imaging section.

[0136] (2) Trajectory Planning

[0137] In this embodiment, as mentioned above, the working process of each axis is divided into three stages: the start-up stage, the scanning stage and the stop stage. In order to ensure the synchronization of the scanning of each axis in the imaging segment, the trajectory of the start-up stage and the scanning stage needs to be strictly planned:

[0138] 21) Trajectory planning during the startup phase:

[0139] Assume that: in the acceleration section of the startup phase, each axis starts from speed 0 and performs uniform acceleration motion, and the acceleration time is T QJ ;but:

[0140] The acceleration of each axis during the acceleration phase of the startup phase is:

[0141]

[0142] The motion angle increment of each axis in the acceleration section during the startup phase is:

[0143]

[0144] Assume that: In the uniform speed section of the startup phase, each axis Maintain uniform motion, and the uniform motion time of each axis is T QY ;but:

[0145] The motion angle increment of each axis in the uniform speed section during the startup phase for:

[0146]

[0147] In order to make the three axes reach their respective imaging starting angles at the same time, the motion angle increment curve of each axis in the startup phase is obtained comprehensively. for:

[0148]

[0149] The angle and angular velocity of the startup phase planned by the above method are as follows Figure 2 As shown. Figure 2 It can be seen that the three axes reach the sub-satellite point (0° position) at the same time.

[0150] 22) Trajectory planning during the scanning phase:

[0151] Active shaft:

[0152] Assume that: During the scanning phase, the active axis starts from the imaging starting point. Make a full rotation at a uniform speed; then, the angle increment curve of the active axis in the scanning phase for:

[0153] First follower axis:

[0154] Assume that: in the scanning phase, the first follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the first follower axis in the non-imaging segment includes five stages: uniform speed segment A1, acceleration segment B, uniform speed segment A2, deceleration segment C and uniform speed segment A3, and the time experienced is respectively and The speed of the acceleration section B and the deceleration section C is a 1 / 2 sine curve to ensure that there is no sudden change in speed during the entire scanning process. The uniform speeds of the uniform speed sections A1, A2 and A3 are the same, all of which are but:

[0155] Angular velocity curve of the first follower axis during the scanning phase for:

[0156]

[0157] Angle increment curve of the first follower axis in the scanning phase for:

[0158]

[0159] Second follower axis:

[0160] Assume that: in the scanning phase, the second follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the second follower axis in the non-imaging segment includes five stages: uniform speed segment A'1, acceleration segment B', uniform speed segment A'2, deceleration segment C' and uniform speed segment A'3, and the time experienced is respectively and

[0161] The speed of the acceleration section B' and the deceleration section C' is a 1 / 2 sine curve to ensure that there is no sudden change in speed during the entire scanning process. The uniform speed of the uniform speed sections A'1, A'2 and A'3 is the same, all of which are but:

[0162] Angular velocity curve of the second follower axis during the scanning phase for:

[0163]

[0164] Angle increment curve of the second follower axis in the scanning phase for:

[0165]

[0166] The angles and angular velocities of the startup phase and the scanning phase planned by the above method are as follows: Figure 3 As shown. Figure 3 It can be seen that in each scanning cycle, the three axes reach the imaging start position and the sub-satellite point (0°) position at the same time.

[0167] (3) System model and decoupling control algorithm

[0168] The three-phase slotless permanent magnet synchronous torque motor drives of the three axes can be equivalent to DC motors, such as Figure 4 As shown, its transfer function G(s) is expressed as follows:

[0169]

[0170] For the 3-axis synchronous scanning system, the following control strategy is adopted:

[0171] Startup phase:

[0172] Each axis adopts a single-axis position-speed dual closed-loop control algorithm, with no coupling between them. Each axis is controlled with the real-time angle command as the target. Among them, the control structure corresponding to the single-axis position-speed dual closed-loop control algorithm is as follows: Figure 5 As shown, its transfer function G 单 (s) means as follows:

[0173]

[0174] Scanning phase:

[0175] The active axis adopts a single-axis position and speed dual closed-loop control algorithm, and only tracks its own real-time angle command. The control structure is as follows: Figure 5 shown.

[0176] The follower axis adopts the synchronous follower control decoupling algorithm, and adjusts the drive amount of the follower axis according to the proportional difference between the follower axis and the active axis. The control structure is as follows Figure 6 As shown, its transfer function G 随 (s) means as follows:

[0177]

[0178] (4) Scanning accuracy simulation results under different control strategies

[0179] For the three-axis synchronous scanning system considered in the present invention, the same given control strategy, the deviation coupling control strategy and the synchronous follow-up decoupling control algorithm described in the present invention are respectively adopted. The synchronous control accuracy of the follow-up axis is as follows: Figure 7 It can be seen that the method described in the present invention can greatly improve the synchronous following accuracy of the follower axis without affecting the tracking effect of the active axis on the instruction.

[0180] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0181] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in the field.

Claims

1. A method for decoupling following and tracking of a space camera scanning control system, characterized in that: include: Determine a control object; wherein the control object is: three independent axes in the space camera scanning system that are not coupled in structure; Through three three-phase slotless permanent magnet synchronous torque motors, the three axes are driven to perform continuous full-circle rotation scanning motion according to the planned trajectory, so that the three axes meet the set requirements. While achieving wide-width imaging, the active axis tracking control and the follower axis synchronous control of the multi-axis scanning mechanism of the space camera are decoupled.

2. The method for decoupling following and tracking of a space camera scanning control system according to claim 1, characterized in that: The three axes are: the driving axis, the first follower axis and the second follower axis.

3. The method for decoupling following and tracking of a space camera scanning control system according to claim 2, characterized in that: The space camera scanning system is divided into imaging section and non-imaging section according to the imaging process.

4. The method for decoupling following and tracking of a space camera scanning control system according to claim 3, characterized in that: Through three three-phase slotless permanent magnet synchronous torque motors, the three axes are driven respectively to perform continuous full-circle rotation scanning motion according to the planned trajectory, so that the three axes meet the following set requirements: 1) the three axes perform uniform and synchronous scanning motion in the imaging segment, and the uniform scanning motion speeds of the three axes in the imaging segment are different; 2) the scanning angle ranges of the three axes in the imaging segment are different, that is, the starting angles and ending angles of the imaging segment of the three axes are different; 3) the imaging segment time of the three axes is the same, that is, the three axes enter the imaging segment at the same time, pass the satellite sub-satellite point at the same time, leave the imaging segment at the same time, and the scanning period of the three axes is the same.

5. The method for decoupling following and tracking of a space camera scanning control system according to claim 4, characterized in that: The space camera scanning system is divided into three stages according to the working process: Start-up phase: Each axis starts to accelerate from rest and reaches its respective imaging segment starting angle at the same time, and the speed when reaching its respective imaging segment starting angle is exactly the uniform scanning speed of each axis in the imaging segment; Scanning phase: starting from the scanning starting position of each axis, the scanning cycle of each axis is the same, and the imaging segment is kept synchronized. Stop phase: Each axis slowly decelerates from the current movement speed until the speed is reduced to 0.

6. The method for decoupling following and tracking of a space camera scanning control system according to claim 5, characterized in that: Also includes: The trajectories of the start-up phase and the scanning phase of each axis are planned to obtain the planned trajectory to meet the synchronization of scanning of each axis in the imaging section.

7. The method for decoupling following and tracking of a space camera scanning control system according to claim 6, characterized in that: Plan the trajectory of each axis during the startup phase, including: Assume that: in the acceleration section of the startup phase, each axis starts from speed 0 and performs uniform acceleration motion, and the acceleration time is T QJ ;but: The acceleration of each axis during the acceleration phase of the startup phase is: in, represents the acceleration of axis i in the acceleration section, Indicates the uniform scanning motion speed of axis i; i = 1, 2, 3; i = 1, indicates the active axis; i = 2, indicates the first follower axis; i = 3, indicates the second follower axis; The motion angle increment of each axis in the acceleration section during the startup phase is: in, Indicates that axis i is in the acceleration segment t A The angular increment of motion at time t A ∈[0,T QJ ]; Assume that: In the uniform speed section of the startup phase, each axis Maintain uniform motion, and the uniform motion time of each axis is T QY ;but: The motion angle increment of each axis in the uniform speed section during the startup phase for: in, Indicates that axis i is in the uniform speed segment t B The angular increment of motion at time t B ∈[0,T QY ]; According to the determined motion angle increment of each axis in the acceleration section of the startup phase and the motion angle increment of each axis in the uniform speed section of the startup phase, the motion angle increment curve of each axis in the startup phase is determined. for: in, represents the end angle of the imaging segment of axis i; according to Determine the trajectory of each axis during the startup phase.

8. The method for decoupling following and tracking of a space camera scanning control system according to claim 7, characterized in that: Plan the trajectory of each axis scanning phase, including: Assume that: During the scanning phase, the active axis starts from the imaging starting point. Make a full rotation at a uniform speed; then: Angle increment curve of the active axis during the scanning phase for: Among them, t c represents the duration of the imaging segment; according to Determine the trajectory of the active axis during the scanning phase. Assume that: in the scanning phase, the first follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the first follower axis in the non-imaging segment includes five stages: uniform speed segment A1, acceleration segment B, uniform speed segment A2, deceleration segment C and uniform speed segment A3, and the time experienced is respectively and The uniform speeds of the uniform speed sections A1, A2, and A3 are the same, all of which are but: Angular velocity curve of the first follower axis during the scanning phase for: in, represents the movement time of the first follower axis in the scanning phase, A 2 Indicates the maximum value of the acceleration change of the first follower shaft in the speed change section; m 2 Indicates the frequency of sinusoidal change of the speed of the first follower axis; Angle increment curve of the first follower axis in the scanning phase for: according to and determining a trajectory of the first follower axis during a scanning phase; Assume that: in the scanning phase, the second follower axis starts from the imaging starting point, first experiences uniform motion in the imaging segment, and then experiences variable speed motion in the non-imaging segment; wherein, in the scanning phase, the variable speed motion of the second follower axis in the non-imaging segment includes five stages: uniform speed segment A'1, acceleration segment B', uniform speed segment A'2, deceleration segment C' and uniform speed segment A'3, and the time experienced is respectively and The uniform speeds of the uniform speed segments A'1, A'2 and A'3 are the same, all of which are but: Angular velocity curve of the second follower axis during the scanning phase for: in, A represents the movement time of the second follower axis in the scanning phase. 3 Indicates the maximum value of the acceleration change of the second follower shaft in the speed change section; m 3 Indicates the frequency of sinusoidal change of the speed of the second follower axis; Angle increment curve of the second follower axis in the scanning phase for: according to and Determine the trajectory of the second follower axis during the scanning phase.

9. The method for decoupling following and tracking of a space camera scanning control system according to claim 8, characterized in that:

10. The method for decoupling following and tracking of a space camera scanning control system according to claim 1, characterized in that: The three-phase slotless permanent magnet synchronous torque motor is equivalent to a DC motor, and the transfer function G(s) is expressed as follows: Where: L represents the equivalent inductance, R represents the equivalent resistance, K t Indicates the current torque coefficient, K s represents the back electromotive force coefficient, J s is the motor moment of inertia, and s represents a complex variable.

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