Attitude dynamic compensation control method for multistage satellite platform with motion load

Abstract

An attitude dynamic compensation control method for a multi-stage satellite platform with a motion load comprises the following steps: establishing a kinetic model of a scanning accessory, analyzing transmission characteristics of disturbance in the multi-stage satellite platform by combining a motion law of the kinetic model, and designing a feed-forward torque compensation method of an upper platform secondary system; calculating disturbance values of the scanning accessory in the upper platform secondary control period and the lower platform primary control period, and designing an angular momentum attitude compensation method of the lower platform; based on a kinetic model of a multistage satellite, designing a multi-step forecasting algorithm, determining the gain of an observer, and reducing the measurement time delay of the sensor; and calculating the control reaction torque of the upper platform, and dynamically correcting the feed-forward compensation value of the lower platform in real time. The attitude control method provided by the invention can be applied to attitude control of a multi-stage satellite platform and a traditional single-stage satellite platform, and high-precision and high-stability attitude control of a multi-stage satellite can be realized.

Description

Technical Field

[0001] The invention relates to a multi-stage satellite platform attitude dynamic compensation control method with a motion load, belonging to the field of satellite attitude control. Background Art

[0002] High-orbit hyperspectral satellites need to maintain ultra-high attitude stability during the imaging process to achieve high-resolution earth observation capabilities. However, the periodic motion of the satellite's motion payload causes disturbances to the satellite platform, aggravating the attitude coupling phenomenon of the multi-stage satellite platform, and seriously affecting the attitude stability of the multi-stage satellite platform and the earth observation capability of the payload. In the case of time delay between the fast and slow control cycles of the multi-stage control system and the sensors, the multi-stage satellite attitude control system that only uses feedback measurement cannot completely eliminate the periodic coupling disturbance of the motion payload, further reducing the attitude control accuracy and stability of the multi-stage satellite platform.

[0003] Faced with new multi-stage satellite platforms with moving payloads, the attitude feedforward compensation control methods used for traditional single-stage satellites have the following shortcomings: (1) The multi-stage coupling phenomenon of multi-stage satellite platforms with moving payloads is serious. The traditional single-stage attitude control method that only uses feedback measurement cannot completely eliminate the periodic coupling disturbance of the moving payload, thereby reducing the attitude control accuracy and stability of the multi-stage satellite platform; (2) The unique primary and secondary control of the multi-stage satellite platform makes the multi-stage control system contain two different control cycles. The traditional satellite attitude compensation control method is not suitable for multi-stage satellite platforms with different control cycles; (3) In engineering applications, the effect of feedforward attitude compensation is heavily dependent on the authenticity of sensor measurements and the accuracy of angular momentum compensation. The existence of time delay leads to a huge difference between the attitude measurement value and the actual value, which reduces the compensation effect of the feedforward attitude compensation control algorithm. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and to design a multi-stage satellite platform attitude dynamic compensation control method with a motion payload for the multi-stage satellite platform attitude control problem when multi-stage coupling disturbances, fast and slow control cycles, inaccurate feedforward compensation and measurement delay exist. The method has small calculation amount, clear and concise control logic and good practicality.

[0005] The technical solution of the present invention is: a multi-stage satellite platform attitude dynamic compensation control method with a motion load, comprising:

[0006] According to the multi-stage satellite structure with motion loads, a dynamic model of the multi-stage satellite is established;

[0007] According to the obtained dynamic model of the multi-stage satellite, the compensation controller of the upper and lower platforms of the multi-stage satellite is designed, and the attitude of the upper and lower platforms of the satellite is compensated;

[0008] According to the established dynamic model of the multi-stage satellite, a multi-step prediction dynamic feedforward compensation controller is designed, and dynamic feedforward compensation is performed on the attitude of the platform under the satellite.

[0009] The multi-stage satellite includes a lower platform and an upper platform of the satellite body, and the dynamic model of the multi-stage satellite includes the dynamic models of the upper and lower platforms of the multi-stage satellite, which are respectively:

[0010]

[0011] In the formula, ω b denote the angular velocity and angular acceleration of the lower platform, I b represents the lower platform inertia matrix, M ds represents the disturbance torque on the lower platform, τ b It represents the control torque of the lower platform, M ps I represents the torque of the upper platform on the lower platform; p represents the inertia of the upper platform, I gu h ,I wu h They represent the rotating frame inertia of the moving load and the rotating scanning mirror inertia in the upper platform coordinate system, S gu ,S wu The rotating frame moment of inertia and the rotating scanning mirror moment of inertia representing the moving load, are the angular accelerations of the rotating frame and the rotating scanning mirror, respectively, T u Indicates the control torque on the upper platform; I σu h is the representation of the rotating frame inertia in the rotating frame coordinate system, I Ωu h is the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system; Γ z =[0 0 1] T , Γ x =[1 0 0] T ; L represents the disturbance torque acting on the upper platform.

[0012] The disturbance torque L is specifically expressed as:

[0013]

[0014] Where Ω represents the angular velocity of the rotating scanning mirror, is the derivative of the rotating frame inertia in the rotating frame coordinate system, represents the angular velocity of the rotating frame, is the derivative of the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system, ω p represents the angular velocity of the upper platform, hs is the angular momentum of the rotating scanning attachment, v p represents the speed of the upper platform, p s represents the momentum of the rotating scanning mirror, is the derivative of the rotating frame inertia in the upper platform coordinate system, is the derivative of the inertia of the rotating scanning mirror in the upper platform coordinate system.

[0015] The compensation controller of the multi-stage satellite lower platform is

[0016] τ b =K bp1 q be +K bi1 ∫q be dt+K bd1 δω be +τ cb

[0017] Where K bp1 ,K bi1 ,K bd1 are the control parameters of the lower platform attitude PID controller, representing the proportional parameter, integral parameter and differential parameter respectively; q be Represents the platform attitude error quaternion, δω be Represents the angular velocity error.

[0018] The lower platform uses angular momentum to control and compensate the lower platform attitude. In the control period T of the lower platform, the attitude compensation torque τ of the lower platform is cb Specifically:

[0019]

[0020] Where Δh b is the angular momentum compensation value of the lower platform within the T period, and the calculation method is as follows:

[0021]

[0022] Where t represents the control period of the upper platform; F 2i is the average disturbance torque of the moving scanning mirror on the upper platform in the ith t period, and the specific calculation method is as follows:

[0023]

[0024] The symbol It represents the average value of the variable in period t.

[0025] The compensation controller of the multi-stage satellite platform is

[0026] τ p =Kpp1 q pe +K pi1 ∫q pe dt+K pd1 δω pe +F 2 '

[0027] Where K pp1 ,K pi1 ,K pd1 represents the control parameters of the upper platform attitude PID controller, which respectively represent the proportional parameter, integral parameter and differential parameter; q pe Represents the upper platform attitude error quaternion, δω pe represents the angular velocity error;

[0028] The upper platform uses force compensation to compensate for the disturbance of the satellite upper platform. The attitude compensation torque of the upper platform is:

[0029] According to the established dynamic model of the multi-stage satellite, a multi-step prediction dynamic feedforward compensation controller is designed, and dynamic feedforward compensation is performed on the attitude of the platform under the satellite, including:

[0030] According to the dynamic model of the multi-level satellite, the sampling period T is set and the dynamic model of the multi-level satellite is discretized as

[0031] x(k+1)=Fx(k)+G[u(k)+w(k)]

[0032] Among them, u(k) represents the input of the discrete system, w(k) represents the nonlinear input of the system; G represents the input matrix, and F represents the system matrix;

[0033] Then the multi-step forecast observer is as follows:

[0034]

[0035] in represents the predicted state value, K represents the gain matrix, and C is the observation matrix;

[0036] Let the multi-step forecast error Then the multi-step forecast error equation is:

[0037]

[0038] Find the error gain matrix K so that F n+1 -The characteristic root of KC is within the unit circle and the predicted value Substitute the measured value q of the lower platform be ,δω be , and update the sub-planet platform controller τ b ;

[0039] Design a dynamic feedforward attitude compensation controller to perform dynamic feedforward attitude compensation on the platform under the satellite. The dynamic feedforward compensation controller for the platform under the satellite is:

[0040] τ b =K bp1 q be '+K bi1 ∫q be 'dt+K bd1 δω be '+τ ck

[0041] Among them, q be ',δω be ' is the forecast value of the multi-step forecast observer, τ ck Represents the dynamic feedforward compensation torque of the platform under the satellite.

[0042] The calculation method of the input matrix G and the system matrix F is as follows:

[0043] G=G 1 B

[0044]

[0045] Where A represents the state matrix in the multi-level satellite continuous model, B represents the input matrix, I represents the identity matrix.

[0046] The dynamic feedforward compensation torque τ of the platform under the satellite ck The calculation method is as follows:

[0047] τ ck =τ cb +α(τ pb -τ cb )

[0048] where τ pb It represents the reaction force of ASP platform on the lower platform, and α represents the dynamic compensation coefficient gain.

[0049] The advantages of the present invention compared with the prior art are:

[0050] (1) The traditional single-stage attitude control method using only feedback measurement cannot completely eliminate the periodic coupling disturbance generated by the motion load in the multi-stage satellite platform. The present invention provides a multi-stage satellite platform with motion load attitude dynamic compensation control method, which combines the refined dynamic model of the motion scanning accessory and its motion law, and utilizes the transmission characteristics of the multi-stage satellite platform disturbance. The attitude feedforward compensation controller of the multi-stage satellite system is designed for the upper platform control system based on the ASP platform and the first-level control system of the lower platform, which can improve the attitude stability of the multi-stage satellite.

[0051] (2) The present invention is the first to calculate the disturbance of the lower platform during the control cycle of the lower platform and design the attitude feedforward compensation controller of the lower platform based on the principle of conservation of angular momentum, targeting the fast and slow control cycle characteristics unique to multi-stage satellite platforms; during the control cycle of the upper platform, the disturbance torque is calculated using the expected trajectory of the motion load, and the attitude feedforward compensation controller of the upper platform is designed based on the torque compensation method. The attitude feedforward compensation controller designed by the present invention can achieve synchronous and accurate compensation of multi-stage disturbances under the fast and slow control cycle characteristics unique to multi-stage satellite platforms.

[0052] (3) The multi-step prediction dynamic compensation control method proposed in this invention realizes real-time observation of the attitude of the satellite platform by designing a multi-step prediction observer, and realizes dynamic and accurate compensation of disturbances by designing dynamic compensation gains. This solves the attitude disturbance problems caused by inaccurate feedforward compensation and measurement delay of traditional satellites, and realizes dynamic and accurate compensation of multi-level satellite disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a multi-level coupling transfer analysis diagram.

[0054] Figure 2 This is the block diagram of feedforward interference compensation control for a multi-stage satellite platform.

[0055] Figure 3 This is the control block diagram of the multi-step prediction feedforward compensation control algorithm based on angular momentum conservation. DETAILED DESCRIPTION

[0056] The present invention provides a method for dynamic compensation control of the attitude of a multi-stage satellite platform with a moving load. The method establishes a dynamic model of a scanning accessory, and combines its motion law to analyze the transmission characteristics of disturbances in the multi-stage satellite platform, and designs a feedforward torque compensation method for the upper platform; calculates the angular momentum disturbance value of the scanning accessory within the upper platform control period and the lower platform control period, and designs an angular momentum attitude compensation method for the lower platform; based on the dynamic model of the satellite platform of the multi-stage satellite system, designs a multi-step prediction algorithm, determines the observer gain, and reduces the sensor measurement delay; designs a dynamic feedforward compensation method, and dynamically corrects the satellite feedforward compensation value in real time to improve the accuracy of the feedforward compensation. The attitude control method proposed in the present invention can be applied to the attitude control of multi-stage satellite platforms and traditional single-stage satellite platforms, and can achieve high-precision and high-stability attitude control of satellites. The specific method steps are as follows:

[0057] (1) Based on the composition of a multi-stage satellite with motion payloads, a dynamic model of the multi-stage satellite is established.

[0058] The multi-stage satellite includes a lower platform and an upper platform of the satellite body, and the dynamic model of the multi-stage satellite includes the dynamic models of the upper and lower platforms of the multi-stage satellite, which are respectively:

[0059]

[0060] In the formula, ω b denote the angular velocity and angular acceleration of the lower platform, I b represents the lower platform inertia matrix, M ds represents the disturbance torque on the lower platform, τ b It represents the control torque of the lower platform, M ps I represents the torque of the upper platform on the lower platform; p represents the inertia of the upper platform, I gu h ,I wu h They represent the rotating frame inertia of the moving load and the rotating scanning mirror inertia in the upper platform coordinate system, S gu ,S wu The rotating frame moment of inertia and the rotating scanning mirror moment of inertia representing the moving load,

[0061] are the angular accelerations of the rotating frame and the rotating scanning mirror, respectively, T u Indicates the control torque on the upper platform; I σu h is the representation of the rotating frame inertia in the rotating frame coordinate system, I Ωu h is the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system; Γ z =

[001] T , Γ x =

[100] T ; L represents the disturbance torque on the upper platform;

[0062]

[0063] In the formula, I p represents the inertia of the upper platform, I gu h ,I wu h are the rotating frame inertia and the rotating scanning mirror inertia of the moving load in the upper platform coordinate system, respectively. gu ,S wu The rotating frame moment of inertia and the rotating scanning mirror moment of inertia representing the moving load,

[0064] are the angular accelerations of the rotating frame and the rotating scanning mirror, respectively, T u Indicates the control torque on the upper platform; I σu his the representation of the rotating frame inertia in the rotating frame coordinate system, I Ωu h is the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system; Γ z =[0 0 1] T , Γ x =[1 0 0] T ; L represents the disturbance torque on the upper platform;

[0065] The disturbance torque L is specifically expressed as:

[0066]

[0067] Where Ω represents the angular velocity of the rotating scanning mirror, is the derivative of the rotating frame inertia in the rotating frame coordinate system, represents the angular velocity of the rotating frame, is the derivative of the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system, ω p represents the angular velocity of the upper platform, h s is the angular momentum of the rotating scanning attachment, v p represents the speed of the upper platform, p s represents the momentum of the rotating scanning mirror, is the derivative of the rotating frame inertia in the upper platform coordinate system, is the derivative of the inertia of the rotating scanning mirror in the upper platform coordinate system.

[0068] The coupling force transmission relationship diagram of a multi-stage satellite platform with a moving load is shown in Figure 1 As shown. The periodic reciprocating motion of the moving load generates a disturbance force on the upper platform; the posture of the upper platform shifts under the action of the disturbance force, further affecting the motion trajectory of the moving load. Secondly, the disturbances from the moving load on the upper platform are transmitted to the lower platform through the ASP platform. At the same time, in order to maintain the stability of the upper platform, the ASP platform further outputs active control force, and its reaction force acts on the lower platform. These two forces of different processes are transmitted to the lower platform through the ASP platform, causing the posture movement of the lower platform. The movement of the lower platform under the action of the disturbance force is further coupled with the load upper platform through the passive link of the ASP platform, affecting the posture stability of the entire system.

[0069] Therefore, by analyzing the multi-stage disturbance transfer path of a multi-stage satellite with a moving payload, it can be seen that when designing an attitude compensation controller for the attitude of a multi-stage satellite platform when the moving payload is working, it is necessary to design attitude controllers for both the upper platform control system based on the ASP platform and the first-level control system of the lower platform. This is a design idea that is different from the traditional satellite attitude control scheme.

[0070] (2) Based on the principle of conservation of angular momentum, a feedforward compensation control method for the attitude of the upper and lower platforms of a multi-stage satellite is designed to perform compensation control on the attitude of the upper and lower platforms of the satellite.

[0071] The first and second level control systems unique to the multi-level satellite platform with motion payloads make the multi-level control system contain two different control cycles: the control cycle t of the upper platform and the control cycle T of the lower platform, and satisfy the following conditions

[0072] 10t≤T

[0073] Lower platform compensation: Since the control period T of the lower platform is large and the control bandwidth is small, the lower platform can adopt the feedforward compensation method based on angular momentum to overcome the influence of interference, that is, using the measured value of the scanning accessory state and the known expected motion trajectory, calculate the average disturbance to the angular momentum of the lower platform within the control period T, and perform feedforward compensation on it.

[0074] Design the compensation controller of the multi-stage satellite lower platform as

[0075] τ b =K bp1 q be +K bi1 ∫q be dt+K bd1 δω be +τ cb (2)

[0076] Where K bp1 ,K bi1 ,K bd1 represents the control parameters of the lower platform attitude PID controller, which respectively represent the proportional parameter, integral parameter and differential parameter. be It represents the quaternion of the platform attitude error, and the angular velocity error is defined as δω be .

[0077] The lower platform uses angular momentum to compensate. According to the law of conservation of momentum, the angular momentum compensation of the star within the period T should be τ cb for

[0078]

[0079] Where Δh b is the angular momentum compensation value of the lower platform within the T period, and the calculation method is as follows

[0080]

[0081] Where t represents the control period of the upper platform, T represents the control period of the lower platform; F 2iis the average disturbance torque of the moving scanning mirror on the upper platform in the ith t period, and the specific calculation method is as follows:

[0082]

[0083] The symbol It represents the average value of the variable in period t.

[0084] Upper platform compensation: Since the load control period t is small and the control bandwidth is high, it can respond to disturbances in a timely manner. Therefore, the upper platform can use force compensation to overcome the interference caused by the movement of the scanning accessory, that is, the known expected motion trajectory of the scanning accessory is used to calculate the disturbance torque on the upper platform and directly compensate for the disturbance torque.

[0085] The upper platform adopts force compensation, and the compensation controller of the upper platform is

[0086] τ p =K pp1 q pe +K pi1 ∫q pe dt+K pd1 δω pe +F 2 (5)

[0087] Where K pp1 ,K pi1 ,K pd1 Represents the control parameters of the upper platform attitude PID controller, which represent the proportional parameter, integral parameter and differential parameter respectively. pe It represents the upper platform attitude error quaternion, and the angular velocity error is defined as δω pe

[0088] (3) Based on the multi-level satellite dynamics model, a multi-step prediction dynamic feedforward compensation controller is designed to perform dynamic feedforward compensation on the attitude of the platform under the satellite.

[0089] The disturbances to the multi-stage satellite platform are all generated by the active pointing super-quiet platform. The existence of rapid disturbances and measurement delays causes a difference between the angular momentum compensation value and the actual disturbance, affecting the compensation effect of the feedforward compensation control. The existence of delays causes a huge difference between the attitude measurement value and the actual value, reducing the real-time performance of the feedforward attitude compensation.

[0090] The present invention compares the feedforward compensation value with the disturbance of the active pointing super-quiet platform on the lower platform and performs dynamic feedforward compensation, thereby realizing accurate compensation of the stellar disturbance. Meanwhile, when the motion load model is accurately known, a multi-step prediction algorithm based on the model is used to reduce the influence of the measurement delay on the feedforward compensation, thereby realizing real-time compensation of the disturbance of the lower platform.

[0091] In order to realize the multi-step prediction observation of the lower platform attitude, the sampling period T is set to discretize the multi-level spacecraft dynamics model into

[0092] x(k+1)=Fx(k)+G[u(k)+w(k)] (6)

[0093] Among them, u(k) represents the input of the discrete system, w(k) represents the nonlinear input of the system, and the calculation method of the input matrix G and the system matrix F is as follows

[0094] The calculation method of input matrix G and system matrix F is as follows

[0095] G=G 1 B

[0096]

[0097] Where A represents the state matrix in the multi-level satellite continuous model, B represents the input matrix, I represents the identity matrix, G 1 The calculation method is as follows

[0098]

[0099] For the spacecraft discrete system equation formula 6, the multi-step prediction equation is as follows

[0100]

[0101] in represents the predicted state value, K represents the gain matrix, and C is the observation matrix.

[0102] Let the multi-step forecast error be The multi-step forecast error equation is:

[0103]

[0104] Find the appropriate error gain matrix K so that F n+1 -The characteristic root of KC is within the unit circle and the predicted value Instead of the lower platform measurement value q be ,δω be , update step 2 satellite platform controller τ b , which can reduce the impact of measurement delay on the system.

[0105] The error between the compensation amount and the actual disturbance leads to a decrease in the effect of attitude compensation control. In order to improve the compensation accuracy of the feedforward compensation control, a dynamic feedforward attitude compensation controller is designed to perform attitude dynamic feedforward compensation on the platform under the satellite. The dynamic feedforward compensation controller of the platform under the satellite is

[0106] τ b =K bp1q be '+K bi1 ∫q be 'dt+K bd1 δω be '+τ ck (9)

[0107] Among them, q be ',δω be ' is the predicted value of the multi-step prediction observer, the dynamic feedforward compensation torque τ of the platform under the star ck The calculation method is as follows

[0108] τ ck =τ cb +α(τ pb -τ cb ) (10)

[0109] where τ pb represents the reaction force of the ASP platform on the lower platform, α(τ pb -τ cb ) represents the dynamic compensation value of the lower platform, α represents the dynamic compensation coefficient factor, and selecting an appropriate compensation coefficient α can achieve accurate dynamic compensation of disturbances. Since the disturbance to the lower platform comes entirely from the reaction torque of the ASP platform, the dynamic feedforward compensation principle of the lower platform is to take the reaction torque of the actuator into account in the feedforward compensation, and correct the feedforward compensation amount to improve the accuracy of the feedforward compensation of the lower platform. The principle block diagram of step (3) is shown in Figure 3 shown.

[0110] Example

[0111] like Figure 2 As shown, the attitude dynamic compensation control method of a multi-stage satellite platform with a moving payload proposed by the present invention consists of three technical points. Taking a multi-stage satellite with a moving payload as an example, the specific implementation method of the present invention is introduced.

[0112] Assume that the parameters of the multi-stage satellite platform with motion payload are as follows

[0113] Table 1 Parameters of multi-stage spacecraft with motion payloads

[0114]

[0115] Star control period T = 100ms, star delay T d = 100ms, the upper platform control cycle t = 5ms, the upper platform and the lower platform remain stable when the scanning mirror is working, the scanning outer frame remains stationary relative to the load, and the desired trajectory of the scanning swing mirror Θ d is a cosine curve with a frequency of 1 / π and an amplitude of 5(°), and its expected angular velocity W d and angular acceleration As shown below

[0116]

[0117] (1) A dynamic model of a satellite platform with a moving payload is established. The transmission characteristics of disturbances in the multi-stage satellite platform are analyzed in combination with its motion law, and a feedforward torque compensation method for the multi-stage satellite platform is designed.

[0118] The kinetic model is established through step (1) and Figure 1 From the analysis of the multi-stage disturbance transfer path shown, it can be seen that when designing the attitude compensation controller for the multi-stage satellite platform attitude when the moving load is working, it is not only possible to design the attitude compensation controller for the upper platform control system based on the ASP platform, but also to design the corresponding attitude compensation controller for the first-level control system of the lower platform. This is a design idea that is different from the traditional satellite attitude control scheme.

[0119] In addition, the different control cycles lead to different attitude compensation control strategies for the upper and lower platforms. Since the load control cycle t is small and the control bandwidth is high, it can respond to disturbances in a timely manner. Therefore, the known expected motion trajectory of the scanning accessory is used to calculate the disturbance torque on the load and directly compensate for the disturbance torque; however, since the control cycle T of the lower platform is large and the control bandwidth is small, the measured value of the scanning accessory state and the known expected motion trajectory are used to calculate the disturbance to the angular momentum of the lower platform within the control cycle T, and feedforward compensation is performed on it.

[0120] (2) Calculate the angular momentum disturbance value of the scanning attachment within the upper platform control period t and the lower platform control period T, and design the angular momentum attitude compensation method of the lower platform in combination with the multi-stage satellite system.

[0121] According to step (2), the compensation controller of the multi-stage satellite lower platform is designed as

[0122] τ b =K bp1 q be +K bi1 ∫q be dt+K bd1 δω be +τ cb

[0123] Where K bp1 ,K bi1 ,K bd1 represents the control parameters of the lower platform attitude PID controller, which respectively represent the proportional parameter, integral parameter and differential parameter. be It represents the quaternion of the platform attitude error, and the angular velocity error is defined as δω be .

[0124] The lower platform uses angular momentum to compensate. According to the law of conservation of momentum, the angular momentum compensation of the star within the period T should be τ cb for

[0125]

[0126] Where Δh b is the angular momentum compensation value of the lower platform within the T period, and the calculation method is as follows

[0127]

[0128] Where t represents the control period of the upper platform, T represents the control period of the lower platform; F 2i is the average disturbance torque of the moving scanning mirror on the upper platform during period t, F 2 The specific calculation method is as follows

[0129]

[0130] Active pointing platform compensation on the ultra-quiet platform: Since the load control period t is small and the control bandwidth is high, it can respond to disturbances in a timely manner. Therefore, the upper platform can use force compensation to overcome the interference caused by the movement of the scanning accessory, that is, the known expected motion trajectory of the scanning accessory is used to calculate the disturbance torque on the load and directly compensate for the disturbance torque.

[0131] The upper platform adopts force compensation, and the compensation controller of the upper platform is

[0132] τ p =K pp1 q pe +K pi1 ∫q pe dt+K pd1 δω pe +F 2

[0133] Where K pp1 ,K pi1 ,K pd1 Represents the control parameters of the upper platform attitude PID controller, which represent the proportional parameter, integral parameter and differential parameter respectively. pe It represents the upper platform attitude error quaternion, and the angular velocity error is defined as δω pe

[0134] (3) Based on the dynamic model of the satellite platform of the multi-stage satellite system, a multi-step prediction dynamic feedforward algorithm is designed to determine the observer gain and reduce the sensor measurement delay.

[0135] Using step (3) to design a multi-step prediction algorithm, set the sampling period T = 100ms, and discretize the multi-level spacecraft dynamics model into

[0136] x(k+1)=Fx(k)+G[u(k)+w(k)]

[0137] A multi-step forecast observer is designed according to formulas 5, 6, and 7, and the feedback measurement value of the platform state is replaced by the multi-step forecast observation value to reduce the measurement delay.

[0138] The closer the characteristic root of the multi-step prediction error equation is to the center of the unit circle, the faster the observation speed and the smaller the observation error. Therefore, the error gain matrix K selects the unit matrix to make F n+1 -KC's characteristic root is inside the unit circle. Assume the system delay is T d , then the number of forecast steps n is, where Indicates rounding up to an integer

[0139]

[0140] Design dynamic compensation parameters and dynamically correct the feedforward compensation of the lower platform in real time. In order to improve the compensation accuracy of the feedforward compensation control, a dynamic compensation controller is designed using step (3). The dynamic feedforward compensation controller of the lower platform of the satellite is

[0141] τ b =K bp1 q be '+K bi1 ∫q be 'dt+K bd1 δω be '+τ ck

[0142] Among them, q be ',δω be ' is the predicted value of the multi-step prediction observer, the dynamic feedforward compensation torque τ of the platform under the star ck The calculation method is as follows

[0143] τ ck =τ cb +α(τ pb -τ cb )

[0144] Where α(τ pb -τ cb ) represents the dynamic compensation value of the star, and α represents the dynamic compensation coefficient factor.

[0145] The attitude control of the satellite platform and the payload platform both use PID controllers to achieve basic stability of the attitude of the multi-stage satellite platform. For this example, a PID controller with a bandwidth of 0.1 Hz and a damping ratio of 0.7 is selected for the lower platform, and a PID controller with a bandwidth of 3 Hz and a damping ratio of 0.7 is selected for the upper platform.

[0146] 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 can make possible changes and modifications to the technical solution of the present invention by using the 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.

Claims

1. A method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load, characterized in that: include: According to the multi-stage satellite structure with motion loads, a dynamic model of the multi-stage satellite is established; According to the obtained dynamic model of the multi-stage satellite, the compensation controller of the upper and lower platforms of the multi-stage satellite is designed, and the attitude of the upper and lower platforms of the satellite is compensated; According to the established dynamic model of the multi-stage satellite, a multi-step prediction dynamic feedforward compensation controller is designed, and dynamic feedforward compensation is performed on the attitude of the platform under the satellite.

2. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 1 is characterized in that: The multi-stage satellite includes a lower platform and an upper platform of the satellite body, and the dynamic model of the multi-stage satellite includes the dynamic models of the upper and lower platforms of the multi-stage satellite, which are respectively: In the formula, ω b denote the angular velocity and angular acceleration of the lower platform, I b represents the lower platform inertia matrix, M ds represents the disturbance torque on the lower platform, τ b It represents the control torque of the lower platform, M ps I represents the torque of the upper platform on the lower platform; p represents the inertia of the upper platform, I gu h ,I wu h They represent the rotating frame inertia of the moving load and the rotating scanning mirror inertia in the upper platform coordinate system, respectively. gu ,S wu The rotating frame moment of inertia and the rotating scanning mirror moment of inertia representing the moving load, are the angular accelerations of the rotating frame and the rotating scanning mirror, respectively, T u Indicates the control torque on the upper platform; I σu h is the representation of the rotating frame inertia in the rotating frame coordinate system, I Ωu h is the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system; Γ z =[001] T , Γ x =[100] T ; L represents the disturbance torque acting on the upper platform.

3. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 2 is characterized in that: The disturbance torque L is specifically expressed as: Where Ω represents the angular velocity of the rotating scanning mirror, is the derivative of the rotating frame inertia in the rotating frame coordinate system, represents the angular velocity of the rotating frame, is the derivative of the inertia of the rotating scanning mirror in the rotating scanning mirror coordinate system, ω p represents the angular velocity of the upper platform, h s is the angular momentum of the rotating scanning attachment, v p represents the speed of the upper platform, p s represents the momentum of the rotating scanning mirror, is the derivative of the rotating frame inertia in the upper platform coordinate system, is the derivative of the inertia of the rotating scanning mirror in the upper platform coordinate system.

4. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 3 is characterized in that: The compensation controller of the multi-stage satellite lower platform is t b =K bp1 q be +K bi1 ∫q be dt+K bd1 here be +t cb Where K bp1 ,K bi1 ,K bd1 are the control parameters of the lower platform attitude PID controller, representing the proportional parameter, integral parameter and differential parameter respectively; q be Represents the platform attitude error quaternion, δω be Represents the angular velocity error.

5. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 4 is characterized in that: The lower platform uses angular momentum to control and compensate the lower platform attitude. In the control period T of the lower platform, the attitude compensation torque τ of the lower platform is cb Specifically: Where Δh b is the angular momentum compensation value of the lower platform within the T period, and the calculation method is as follows: Where t represents the control period of the upper platform; F 2i is the average disturbance torque of the moving scanning mirror on the upper platform in the ith t period, and the specific calculation method is as follows: The symbol It represents the average value of the variable in period t.

6. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 4 is characterized in that: The compensation controller of the multi-stage satellite platform is τ p =K pp1 q pe +K pi1 ∫q pe dt+K pd1 δω pe +F2' Where K pp1 ,K pi1 ,K pd1 represents the control parameters of the upper platform attitude PID controller, which respectively represent the proportional parameter, integral parameter and differential parameter; q pe Represents the upper platform attitude error quaternion, δω pe Represents the angular velocity error.

7. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 6 is characterized in that: The upper platform uses force compensation to compensate for the disturbance of the satellite upper platform. The attitude compensation torque of the upper platform is:

8. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 4 is characterized in that: According to the established dynamic model of the multi-stage satellite, a multi-step prediction dynamic feedforward compensation controller is designed, and dynamic feedforward compensation is performed on the attitude of the platform under the satellite, including: According to the dynamic model of the multi-level satellite, the sampling period T is set and the dynamic model of the multi-level satellite is discretized as x(k+1)=Fx(k)+G[u(k)+w(k)] Among them, u(k) represents the input of the discrete system, w(k) represents the nonlinear input of the system; G represents the input matrix, and F represents the system matrix; Then the multi-step forecast observer is as follows: in represents the predicted state value, K represents the gain matrix, and C is the observation matrix; Let the multi-step forecast error Then the multi-step forecast error equation is: Find the error gain matrix K so that F n+1 -The characteristic root of KC is within the unit circle and the predicted value Substitute the measured value q of the lower platform be ,δω be , and update the sub-planet platform controller τ b ; Design a dynamic feedforward attitude compensation controller to perform dynamic feedforward attitude compensation on the platform under the satellite. The dynamic feedforward compensation controller for the platform under the satellite is: t b =K bp1 q be '+K bi1 ∫q be 'dt+K bd1 here be '+t ck Among them, q be ',δω be ' is the forecast value of the multi-step forecast observer, τ ck Represents the dynamic feedforward compensation torque of the platform under the satellite.

9. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 8, characterized in that: The calculation method of the input matrix G and the system matrix F is as follows: G=G1B Where A represents the state matrix in the multi-level satellite continuous model, B represents the input matrix, I represents the identity matrix.

10. The method for dynamic compensation control of attitude of a multi-stage satellite platform with a moving load according to claim 8, characterized in that: The dynamic feedforward compensation torque τ of the platform under the satellite ck The calculation method is as follows: t ck =t cb +a(t pb -t cb ) where τ pb It represents the reaction force of ASP platform on the lower platform, and α represents the dynamic compensation coefficient gain.

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