Attitude And Joint Motion Fuzzy Control Of Free-floating Space Robot Based On Extended State Observer

With the rapid development of the aerospace industry,the human has achieved milestone development on the depth and breadth of space exploration.Space robot can adapt to the complex working experiment in the space,especially its high performance in high-risk,highly repetitive projects.It also lays the foundation for the development of China's aerospace industry and plays a critical role in the continuous exploration of space.In order to reduce the fuel consumption,the space robot is normally designed in the form of uncontrolled carrier position.However,to make sure the installed communication equipment can be working effectively,there are specific requirements for the carrier posture.Thus,in this paper,the free-floating space robot system is studied.The free-floating rigid space robot with uncontrolled position and controlled posture and the free-floating flexible joint space robot with uncontrolled attitude and position are discussed in the dynamic model.There is an extended state observer fuzzy based on active disturbance rejection control method under the influence of model uncertainty and other factors.First of all,on the basis of the physical model of a planar two-pole space manipulator,the momentum and momentum moment conservation relations existing in the space robot system are applied.The modeling method of the second type Lagrangian equation is applied as well to establish rigid and flexible system dynamic equations respectively.By utilizing singular perturbation method,the free-floating flexible joint space robot system is divided into fast change subsystem and slow change subsystem.Through the active suppression of the elastic vibration generated by the flexible joints,the fast subsystem is controlled by speed difference feedback method while the slow subsystem is controlled by rigid arm control scheme.The building of both models establishes the mathematical modeling foundation for further control system design.Secondly,the ESO is designed based on active disturbance rejection control method.Without determining the accurate physical model of the system,the internal disturbance of the system is evaluated instantly,and the uncertainty part of the system is observed and compensated.This eliminates the influence of the uncertainty on the system,improves the controllability of the system.Meanwhile,this thesis designs the nonlinear error feedback rate with the combination of fuzzy control technology adjusts and selects proper parameters to achieve the system's trajectory.tracking performance.As a result,the robotic joint decoupling control can be achieved,making the actual trajectory track the desired track much faster.The combination of both control scheme ensures the stability of the system,as well as the accuracy of trajectory tracking.With the stability analysis by selecting reasonable Lyapunov function,the stability of control system can be verified.Eventually,the two-link robot is considered as the object for MATLAB simulation.The simulation results proved the feasibility and effectiveness of the control method.