An Active Disturbance Rejection Control Method for Space Robots with Actuator Saturation

Abstract

The invention discloses an auto disturbance rejection control method for a space robot with actuator saturation. The method comprises the following steps: arranging a proper transition process for anexpected track and posture of a system by designing a tracking differentiator, and meanwhile, acquiring a differential signal with an expected value to make preparation for subsequent controller design; and designing a sampling expansion state observer by utilizing a discrete output signal, performing real-time estimation on the total non-linear uncertain items which are formed by the state of thespace robot system as well as coupling and external disturbance, and compensating the estimation values of the non-linear uncertain items into an error feedback control rate. By the method, adverse influence on the system by non-linear factors such as internal and external disturbance can be avoided, and the fact that an actuation mechanism implements accurate position and posture control on thespace robot within the saturation range can be guaranteed. The control strategy provided by the invention has a good control effect on the space robot system considering sampling output and with actuator saturation, and can be widely applied to other non-linear systems.

Description

technical field [0001] The invention belongs to the field of servo control of a space robot system, and relates to a space robot self-disturbance rejection control method with actuator saturation. Background technique [0002] For space robots in deep space that perform complex operations such as rendezvous and docking, orbit and attitude reset, debris capture, and space station construction, the coupling between their own states, planetary atmospheric drag, light pressure, and solar electromagnetic radiation , gravitational field and magnetic field will produce a certain disturbance torque on the space robot orbit and attitude movement, which will have a considerable impact on the long-term space operation task. At present, for the control of space robots, researchers have proposed control strategies such as PID control, optimal control, adaptive control, and sliding mode control. Among them, although the PID control method is simple and effective, with the continuous impr...

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Problems solved by technology

Among them, although the PID control method is simple and effective, with the continuous improvement of the control precision requirements and the complex and changeable system characteristics, the PID control has shown its shortcomings; the optimal control can make a certain control index reach the extreme value, which has a relatively high performance. Strong robustness, but the algorithm still needs to be optimized; the passive adaptive control law realizes the attitude control of the space robot system under the condition of unknown moment of inertia; the sliding mode control has strong robustness and better interference suppression effect, but There will be phenomena such as system output chattering

With the increasing complexity of spacecraft and the increasing time-varying, nonlinear and uncertainties of the system, the above-mentioned control methods are difficult to play an effective role, and the control effect is not ideal

At the same time, with the advancement of computer technology, the control of the space robot system is no exception to the computer control system, that is, it obtains the system state information measured by the sensor through the computer discrete time sampling, and then realizes the control of the system; in addition , due to the limitations of the space robot actuator itself or the working environment, it is necessary to limit the amplitude of the space robot actuator

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