Near-earth magnetic control cube satellite attitude self-adaption fault-tolerant control method

Abstract

The invention provides a near-earth magnetic control cube satellite attitude self-adaption fault-tolerant control method. The method comprises the steps that according to the received external disturbance condition, H infinity robust performance indexes are constructed, the closed loop feedback gain is determined, and the disturbance influence is restrained; for the actuator saturation regime, saturation isolation links are designed, the robust control is improved, H infinity robust control with saturation isolation is formed, the normal control effect is kept, and a system can avoid control performance deterioration caused by actuator saturation; on the basis, a control compensator based on the dynamic structure self-adaption neural network is introduced so as to offset changes of a control system model caused by small faults of the actuator, and therefore self-adaption fault-tolerant control rules are constructed, rapid and effective reconfiguration control is achieved, the attitudeis kept within the ideal range, and it is ensured that a satellite is operated stably and reliably. The method is used for self-adaption fault-tolerant control over the uncertain time-varying nonlinear system under the conditions of external disturbance, small faults of the actuator and saturation.

Description

technical field [0001] The invention relates to the technical field of adaptive robust fault-tolerant control of an uncertain time-varying nonlinear continuous control system, in particular to an attitude adaptive fault-tolerant control method of a magnetically controlled cube star near the earth. Background technique [0002] CubeSat is a hot spot in the field of microsatellites in recent years. It is widely used in universities to carry out aerospace science research and education. It has the characteristics of light weight, low cost, short development cycle, and fast entry into orbit. , ships, aviation aircraft and other monitoring. Obviously, the accurate positioning and attitude control of the CubeSat will directly affect the accuracy of the telemetry data. In order to meet the increasingly high requirements for the stability, reliability and accuracy of the spaceborne platform, an effective and good performance attitude fault-tolerant control system is designed. It ha...

AI Technical Summary

Problems solved by technology

The magnetic torque device uses magnetic rods in three directions to achieve three-axis stable control, and the magnetic rods generate magnetic torque from the coils that are energized. After a long period of work, the coils will heat up, and their performance may decline, which will lead to attitude control effects. Therefore, for magnetron satellites, it is necessary to consider the fault-tolerant control strategy when the actuator part is damaged

When the magnetic torquer is actually working, it is limited by the physical characteristics of the magnetic bar, and its output amplitude must usually be within the allowable range and cannot be increased infinitely, otherwise the actuator will be saturated, and the control cannot be performed normally. Instructions from the controller, making the control performance of the system degraded or even unstable

Generally, actuator saturation will not occur when the satellite is in normal operation. However, when the satellite starts to operate, or when a failure occurs for reconfiguration control, due to drastic changes in the system state, the actuator will be saturated very quickly. Once the saturation time is too long and the If there is no measure to adjust in time, it will lead to the failure of the control function of the system. Therefore, in order to avoid this situation, it is necessary to fully consider the processing method of actuator saturation in the attitude fault-tolerant control, and add a saturation signal isolation link in the control method. Insulate the system from actuator saturation and maintain satisfactory dynamic performance

[0004] In the attitude control of near-Earth magnetron small satellites, an important issue that needs to be considered is the influence of external disturbances on satellite attitude, such as gravity moment, solar radiation, air resistance and internal noise, which will lead to the decline of control performance

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