Performance degradation modeling method for orthogonal pentagonal pyramid control moment gyroscope cluster of space station

Abstract

The invention provides a modeling theory for performance degradation of an orthogonal pentagonal pyramid control moment gyroscope cluster for a space station, and aims to solve the problem of performance degradation modeling of multiple moving bodies in complex spatial layout. Particularly, a high-precision attitude control cluster which is oriented inside and outside a space station assembly cabin and is of an orthogonal double-pentagonal pyramid structure and composed of 12 control moment gyroscopes serves as an object, and a performance degradation model under the electricity-magnetism-force-heat multi-field coupling constraint condition is established from the perspective of dynamics and energy transfer. A performance degradation model is established layer by layer around a control moment gyroscope monomer, a pentagonal pyramid multi-body cluster and an orthogonal double-pentagonal pyramid cluster. By uniformly mapping multi-modal coupling performance degradation of a single body and a cluster into pseudo-disturbance description, standardized expression of performance degradation of a GMG cluster with a complex spatial configuration is realized, and performance degradation of a control moment gyroscope high-precision attitude control cluster with an orthogonal pentagonal pyramid configuration inside and outside a space station combination cabin is accurately described.

Description

Technical Field

[0001] The invention relates to a system-level modeling method for fault diagnosis and prediction management, and in particular to a performance degradation modeling method for a space station orthogonal pentagonal pyramid control moment gyro cluster. Background Art

[0002] The active health of the control moment gyro cluster on orbit is an important guarantee for maintaining the safety and reliability of the attitude control system of the space station, and an important basis for carrying out the intelligent construction of future spacecraft and space precision detection missions. The present invention takes the control moment gyro cluster of two sets of orthogonal pentagonal pyramids (one set each for the Tianhe core module and the Wentian experimental module) of the space station with high redundancy as the research object. Each set of control moment gyro contains 6 control moment gyro monomers, of which 5 monomer frame axes are axially symmetrically distributed on the main axis of the regular dodecahedron, and the 6th control moment gyro frame axis is parallel to the body axis of the cone. The control moment gyro monomer includes two main bodies: a rotor system and a frame system, wherein the rotor system provides the monomer angular momentum size for the high-speed rotor, and the frame system adjusts the monomer angular momentum direction through the frame angular position. Under the pentagonal pyramid space configuration, the control moment gyro cluster synthesizes the torque and outputs the corresponding angular momentum, and together with the space station, constitutes a system of total angular momentum conservation, which meets the space station's large torque, fast response and high-precision attitude adjustment mission requirements. This redundant configuration provides sufficient margin for output torque and angular momentum, and can ensure three-axis attitude control of the attitude control system in the event of failure of 1 to 2 units.

[0003] However, the control moment gyro monomer has cross-linked coupling of multiple physical fields such as electric, magnetic, mechanical and thermal, and also faces the problems of low telemetry data sampling rate and limited perception, such as the lack of key degradation parameters such as bearing vibration and friction torque. Under the coupling of multiple physical fields and limited perception, the existing performance degradation methods of typical electromechanical products are difficult to effectively meet and cover the performance degradation prediction needs of the control moment gyro cluster of the space station. On the one hand, the existing control moment gyro monomer performance degradation modeling method mainly establishes the performance degradation model with the rotor as the core, which cannot describe the impact of the energy interaction between the components under multi-field coupling on the control moment gyro monomer level; on the other hand, the existing performance degradation method of typical electromechanical products with the ground experimental environment as the core relies on sufficient observable parameters and cannot effectively deal with the difficulties of real application scenarios under limited perception. In addition, the orthogonal pentagonal pyramid configuration control moment gyro cluster assembly of the space station has the characteristics of complex multi-moving body spatial layout. The hierarchical characterization of the overall degradation from the control moment gyro monomer to the control moment gyro cluster poses new challenges to the active health of the control moment gyro cluster on orbit. Therefore, it is necessary to study and establish a performance degradation modeling theory for control moment gyro clusters, which can accurately describe the energy interaction between systems and the overall degradation characteristics of the cluster under the conditions of multi-field coupling and limited perception, thereby improving the tracking and prediction capabilities of the on-orbit status of control moment gyro units and clusters.

[0004] Aiming at the high-precision attitude control cluster of an orthogonal double pentagonal pyramid configuration composed of 12 control moment gyroscopes inside and outside the cabin of the space station assembly, the present invention aims to overcome the difficulty of modeling the performance degradation of multiple moving bodies in a complex space layout, and establish a performance degradation model under the conditions of electro-magnetic-mechanical-thermal multi-field coupling constraints from the perspective of dynamics and energy transfer. The performance degradation model will be established layer by layer around the control moment gyroscope monomer, pentagonal pyramid multi-body cluster and orthogonal double pentagonal pyramid cluster. By uniformly mapping the multi-modal coupling performance degradation of the monomer and the cluster into a pseudo-disturbance description, the standardized expression of the performance degradation of the GMG cluster in a complex space configuration is realized, and the performance degradation of the high-precision attitude control cluster of the control moment gyroscope in the orthogonal pentagonal pyramid configuration inside and outside the cabin of the space station assembly is accurately described. Summary of the invention

[0005] Aiming at the performance degradation modeling problem of multiple moving bodies in complex space layout, a control moment gyro cluster performance degradation model method under the condition of electro-magnetic-mechanical-thermal multi-field coupling constraints is established from the perspective of dynamics and energy transfer. The transformation from the perspective of single body modeling to the perspective of group modeling is achieved, which meets the high precision and strong stability requirements of the space station attitude system in real scenarios and enhances the high reliability during service.

[0006] The present invention will establish performance degradation models layer by layer around control moment gyro monomers, pentagonal pyramid multi-body clusters and orthogonal double pentagonal pyramid clusters. By uniformly mapping the multi-modal coupling performance degradation of monomers and clusters into pseudo-disturbance descriptions, the standardized expression of the performance degradation of control moment gyro clusters in complex space configurations can be achieved, and the performance degradation of the control moment gyro high-precision attitude control cluster in the orthogonal pentagonal pyramid configuration inside and outside the cabin of the space station assembly can be accurately described, breaking through the performance degradation modeling problem of control moment gyro under the coupling of electro-magnetic-mechanical-thermal multi-physical fields in complex space. The performance degradation modeling theory of the orthogonal pentagonal control moment gyro cluster for the space station disclosed in the present invention mainly includes two steps: first, completing the performance degradation modeling of each component of the control moment gyro monomer; second, completing the performance degradation modeling of the control moment gyro cluster. The specific steps are as follows:

[0007] S1: Overall performance modeling of the control moment gyro unit driven by dual models

[0008] S1 includes S101, S102 and S103; S101: high-speed rotor modeling; S102: rotor motor modeling; S103: high-speed bearing modeling; S104: frame motor modeling. Combining the key physical fields and performance degradation parameters of the above components, using the force field under the dynamic model framework as an intermediary, and integrating the dynamic characteristics and energy transfer characteristics, the components are organically integrated to complete the overall performance modeling and standardized expression of the control moment gyro driven by the dual model.

[0009] S2: Distribution of synthetic torque degradation of the control moment gyro cluster under pseudo-vibration disturbance; Map the degradation of the single unit to the pseudo-vibration disturbance, describe the attitude control noise of the control moment gyro cluster caused by the single unit degradation, and characterize the performance degradation of the attitude control of the entire control moment gyro cluster. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 To control the structure of the moment gyro and the output angular momentum distribution characteristics of the pentagonal pyramid configuration.

[0011] Figure 2 In order to model and standardize the performance degradation of the control moment gyro cluster, the specific cause-effect relationship and information flow direction between the subsystems and components of the control moment gyro are described.

[0012] Figure 3 To control the total angular momentum conservation system formed by the moment control gyro cluster and the space station, when the moment control gyro cluster produces a synthetic torque distribution and outputs the corresponding angular momentum, it forms a total angular momentum conservation system with the space station. Specific implementation plan

[0013] S1: Overall performance modeling of the control moment gyro unit driven by dual models

[0014] The present invention takes the control moment gyro clusters of two sets of orthogonal pentagonal pyramids (one set each for the Tianhe core module and the Wentian experimental module) with high redundant configuration in the space station as the research object. Each set of control moment gyro contains 6 control moment gyro monomers, of which 5 monomer frame axes are axially symmetrically distributed on the main axis of the regular dodecahedron, and the 6th control moment gyro frame axis is parallel to the body axis of the cone. The control moment gyro monomer contains two major bodies: a rotor system and a frame system, wherein the rotor system provides the monomer angular momentum size for the high-speed rotor, and the frame system adjusts the monomer angular momentum direction through the frame angular position. Under the pentagonal pyramid space configuration, the control moment gyro cluster synthesizes torque and outputs corresponding angular momentum, and together with the space station, it constitutes a system of total angular momentum conservation, which meets the space station's large torque, fast response and high-precision attitude adjustment mission requirements. The redundant configuration provides sufficient margin for output torque and angular momentum, and can still ensure the three-axis attitude control of the attitude control system in the event of failure of 1 to 2 monomers. The structural composition of the control moment gyro and the output angular momentum distribution characteristics of the pentagonal pyramid configuration are shown in the figure. Figure 1 shown.

[0015] From the perspective of the performance degradation of the control moment gyro unit, the present invention mainly considers the two core subsystems of the control moment gyro: the rotor system and the frame servo system. The rotor system provides the angular momentum for the high-speed rotor, and the frame servo system drives the high-speed rotor to rotate and change the direction of the angular momentum by adjusting the frame angular position. Among them, the rotor system includes a high-speed rotor (rotating mass body), a rotor motor (brushless DC motor, including a drive circuit), and a high-speed bearing; the frame system includes a frame, a frame motor (permanent magnet synchronous motor, including a drive circuit), a conductive ring, and a frame bearing. The core characteristics of the control moment gyro components are summarized as shown in Table 1, including a high-speed rotor, a rotor motor, a high-speed bearing, a frame, a frame motor, and a frame bearing. Combining the key physical fields and performance degradation parameters of the above components, using the force field under the dynamic model framework as an intermediary, and integrating the dynamic characteristics and energy transfer characteristics, the components are organically integrated to complete the overall performance modeling and standardized expression of the control moment gyro driven by the dual model. The specific causal relationship and information flow direction between the subsystems and components of the control moment gyro are as follows: Figure 2 shown.

[0016] Table 1 Summary of core characteristics of control moment gyro components

[0017]

[0018] S101: High-speed rotor

[0019] The high-speed rotor output torque vector consists of two parts: the output torque magnitude and the output torque direction. Among them, the angular momentum corresponding to the output torque comes from the rotor system and remains unchanged, and all the energy comes from the rotor motor; the angular momentum direction comes from the frame system. Driven by the frame motor, the frame drives the high-speed rotor to rotate a certain angle to adjust the angular momentum direction. Considering that the high-speed rotor and the rotating shaft are cast as one piece, the moment of inertia of the rotor system is the moment of inertia of the high-speed rotor. The motion equation of the system can be expressed by the following formula:

[0020]

[0021] Where: J R represents the moment of inertia of the high-speed rotor, and Ω represents the angular velocity of the rotor; represents the electromagnetic torque of the rotor motor, represents the friction torque of high-speed bearings, Represents the total load moment of the high-speed bearing, including the radial load moment and disturbance load moment Since the rotation of the high-speed rotor will generate radial loads on the high-speed bearings, there is a disturbance load torque. When the high-speed bearings generate disturbance load torques, they will affect the rotor system. In particular, the motor rotor is fixedly connected to the rotating mass body, so ω R=Ω.

[0022] S102: Rotor Motor

[0023] The rotor motor is the total energy source of the entire rotor system, involving the energy conversion of the electric-magnetic-force multi-physics field, and outputting the electromagnetic torque The invention establishes a mathematical model of the DC motor mechanism with electronic power switch commutation, and uses the electronic power switch to commutate the three-phase winding R r =[R ra , R rb , R rc ] are energized alternately, thereby forming a step-by-step rotating magnetic field to drive the rotor to run synchronously. Assuming that the three-phase winding resistance is equal and has the same degradation trend, the output electromagnetic torque is:

[0024]

[0025] Where: represents the output shaft load torque; B represents the damping coefficient.

[0026] Assume that the moment of inertia of the output shaft is and the output angular velocity is ω R , then the motion equation of the motor output shaft is as follows:

[0027]

[0028] Where: E a , E b , E c Respectively represent the equivalent back electromotive force of each phase in the three-phase winding; i a ,i b ,i c Represent the currents passing through the three phases respectively. The magnitude of the electromagnetic torque can be achieved by controlling the amplitude of the square wave current output by the inverter.

[0029] S103: High speed bearing

[0030] Under the on-orbit working condition, the high-speed bearing is almost unobservable, and only the shaft temperature parameter is observable. To address the above problems, the present invention uses matrix pulses to simulate the bearing working mode and model the radial loads on the bearing caused by the high-speed rotation of the high-speed rotor and its own faults. Under the on-orbit working condition, the high-speed bearing mainly bears the radial loads generated by the high-speed rotor. At the same time, any bearing failure will also appear as radial movement between the rotor and stator, generating corresponding disturbing radial loads. The main function of high-speed bearings is to support high-speed rotors and ensure that they always move in the desired center of mass to avoid deviations that affect the accuracy of the output torque direction. Modeling from the perspective of radial motion of the bearing can cover both normal and faulty working modes of the bearing.

[0031] Assuming that the bearing fails, the ball will generate disturbances every time it passes the damage point. The disturbance can be described by a rectangular pulse, which includes the pulse amplitude and period, which are related to the disturbance amplitude and the bearing loss width respectively. The mathematical model of the radial vibration of the bearing can be expressed as:

[0032]

[0033]

[0034] Where: and Represent the load torque and the additional disturbance load torque respectively; Δ dist represents the time after the bearing fault point, which can be obtained by the bearing fault d and the tangential speed of the bearing outer ring; δ(t) represents the pulse signal, and its amplitude is and the period is T δ , γ represents the loss weight related to the disturbance load torque. The rectangular pulse signal can well describe the impact of the bearing fault on itself. By controlling the amplitude and period of the rectangular pulse, the bearing fault can be simulated.

[0035] S104: Frame motor

[0036] The present invention establishes a frame motor dynamics model and a voltage model with disturbance. From a dynamics perspective, the frame motor dynamics model is similar to the rotor motor, which generates the corresponding electromagnetic torque T through the electric-magnetic-force energy conversion. se and the output angular velocity ω sm Since the frame motor mainly works under high power conditions, it is easy to produce large changes in the shaft temperature T, which is easy to affect the motor's own winding resistance R s and the magnetic parameter ψ f When the above two factors change, voltage errors will occur, thus affecting the voltage output model of the frame motor. s and ψ f The influence of these factors is uniformly regarded as the disturbance voltage f generated in the voltage equation sd (ΔR s , Δψ f , ΔT), then the influence of shaft temperature factor is introduced on the basis of rotor motor mechanism modeling, and the voltage model containing shaft temperature T disturbance in d / q coordinate system can be expressed as:

[0037]

[0038] Where: f d (ΔR s , Δψ f , ΔT) represents the change in winding resistance and magnetic properties of the motor under shaft temperature disturbance [ΔR s , Δψ f ] and the nonlinear function relationship of the disturbance voltage; R sd , R sq 、i sd and i sq are the d / q winding resistance and current respectively, and L0 is the inductance. Therefore, the dynamic model is modified by the above motor model to obtain the output angular velocity ω sm , then the angular position change of the Δt frame in the unit control cycle is:

[0039] θ sm =ω sm ·Δt (7)

[0040] Since the frame and the rotor are supported and connected by the frame bearing, the frame drives the rotor to reach the desired angular position under the drive of the motor, thereby completing the direction adjustment of the output torque of the control torque gyro.

[0041] S2: Degraded distribution of the synthetic torque of the control torque gyro group under pseudo-vibration disturbance

[0042] The present invention maps the degradation of the single unit to the pseudo-vibration disturbance, describes the attitude control noise caused by the degradation of the single unit of the control moment gyro cluster, and characterizes the performance degradation of the attitude control of the entire control moment gyro cluster. Since there is a closed-loop feedback system for the high-speed rotor speed, the desired angular momentum size will be achieved, and the rotation center of the high-speed rotor will be offset due to internal degradation, thereby generating an angular momentum vector with disturbance effects. Therefore, the present invention proposes to map the degradation of the control moment gyro single unit to the control moment gyro cluster in a pseudo-vibration manner, convert the synthetic output torque from a single value to a torque distribution, and effectively describe the uncertainty of the torque output. Assuming that the angular position offset obeys the Gaussian distribution G(·), the angular position offset under the influence of pseudo-vibration is It can be expressed as:

[0043]

[0044] Where: F(HI) represents the mapping relationship between the monomer health indicator and the pseudo vibration, which is the mean of the Gaussian distribution; σ f Represents the standard deviation of the angular position offset. Then, the output torque distribution of the six control moment gyroscopes is synthesized through the characteristics of the pentagonal pyramid configuration to obtain the synthetic torque distribution of the entire cluster.

[0045] When the control moment gyro cluster generates a synthetic moment distribution and outputs the corresponding angular momentum, it forms a system with total angular momentum conservation with the space station, such as Figure 3 Assume that the angular momentum of the space station itself is H s , the angular momentum of the rotor is H R , then the total angular momentum of the space station system is H T =H R +H s , the angular velocity of the space station relative to the inertial space is ω s , the angular velocity of the high-speed rotor relative to the space station coordinate system is ω R , the external torque M acting on the space station, then:

[0046]

[0047]

[0048] Where: For a control torque gyro, the amount that indicates the change in the rotor angular momentum is Only the quantity (ω) that indicates the change in the direction of the rotor angular momentum s +ω R )×H R , so the above formula becomes:

[0049]

[0050] When the output torque of the control moment gyro is equal to the external torque, the attitude of the star can be kept stable. Changing only the direction of the angular momentum of the control moment gyro avoids the high power consumption associated with changing the magnitude of the angular momentum, thereby achieving the goal of obtaining a larger output torque with lower power consumption. By mapping the degradation of the single unit to pseudo-vibration and combining it with the conservation of angular momentum, the performance degradation modeling of the attitude control of the entire control moment gyro cluster is achieved.

Claims

1. A performance degradation modeling method for a space station orthogonal pentagonal pyramid control moment gyro cluster, characterized in that: The following steps are involved: Overall performance modeling of the control moment gyro unit driven by dual models; mainly consider the two core subsystems of the control moment gyro: the rotor system and the frame servo system; complete the modeling of the key components of the above systems, including the high-speed rotor, rotor motor, high-speed bearing, and frame motor; combine the key physical fields and performance degradation parameters of the above components, use the force field under the dynamic model framework as the intermediary, comprehensively consider the dynamic characteristics and energy transfer characteristics, and organically integrate the components to complete the overall performance modeling and standardized expression of the control moment gyro driven by dual models. The synthetic torque degradation distribution of the control moment gyro cluster under pseudo-vibration disturbance; the degradation of the single unit is mapped to the pseudo-vibration disturbance, the attitude control noise of the control moment gyro cluster caused by the single unit degradation is described, and the performance degradation of the attitude control of the entire control moment gyro cluster is characterized.

2. The method for modeling the overall performance of a control moment gyro unit under dual-model driving according to claim 1, characterized in that: The performance degradation model of key subsystems and components is established, and the overall performance modeling and standardized expression of the control moment gyro are completed with the force field under the dynamic model framework as the medium, including: The moment of inertia of the rotor system is approximated as the moment of inertia of the high-speed rotor, and the motion equation of the system can be expressed by the following formula: Based on the mathematical model of the DC motor mechanism with electronic power switch commutation, the output electromagnetic torque formula is established as follows: The motion equation of the motor output shaft is: Matrix pulses are used to simulate the working mode of the bearing, and the radial loads on the bearing caused by the high-speed rotation of the high-speed rotor and its own faults are modeled. The mathematical model of the radial vibration of the bearing can be expressed as: The bearing fault can be simulated by controlling the amplitude and period of the rectangular pulse. R s and ψ f The influence of these factors is uniformly regarded as the disturbance voltage f generated in the voltage equation sd (ΔR s ,Δψ f ,ΔT), then the influence of shaft temperature factor is introduced on the basis of rotor motor mechanism modeling, and the voltage model containing shaft temperature T disturbance in d / q coordinate system can be expressed as: The output angular velocity ω is obtained by correcting the dynamic model through the above motor model. sm , then the angular position change of the Δt frame in the unit control cycle is: θ sm =ω sm ·Δt.

3. The method for distributing the synthetic moment degradation of a control moment gyro group under pseudo-vibration disturbance according to claim 1, characterized in that: The degradation of the single unit is mapped to the pseudo vibration disturbance to describe the attitude control noise caused by the degradation of the single unit in the control moment gyro cluster, and the performance degradation of the attitude control of the entire control moment gyro cluster is characterized, including: It is proposed to map the degradation of the control moment gyro unit to the control moment gyro cluster in the form of pseudo-vibration, and transform the synthetic output torque from a single value to a torque distribution, which effectively describes the uncertainty of the torque output. Assuming that the angular position offset follows a Gaussian distribution G(·), the angular position offset under the influence of pseudo-vibration is It can be expressed as: Through the characteristics of the pentagonal pyramid configuration, the output torque distribution of the six control torque gyroscopes is synthesized to obtain the synthetic torque distribution of the entire cluster. By mapping the degradation of the single unit into pseudo-vibration and combining it with the conservation of angular momentum, the performance degradation modeling of the attitude control of the entire control moment gyro cluster is realized.

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