The Traject Control Of Flexible Joint Space Manipulator Under Diffrient Gravity

With the development of aviation and further explorations of the unknown outer space, the free-floating space robot is palying an important role in space exploration, and has become the hot issue for domestic and foreign scholars. Because the space environment is particularit, using space manipulator to help or replace astronauts to perform some space tasks is very important for safety and economy. There is a big difference between ground gravity and space gravity environment. From ground alignment to space applications the dynamic model of the manipulator will change which may result in the change of its movement properties. Therefore, it is necessary to design a model-free controller to make the robot system track the desired trajectory in different gravity environment. On the other hand, robot equipped with Harmonic drive transmission brings joint flexibility. Although current space robots equipped with planetary gear trains, there are also considerable joint elasticity effects. Therefore, the trajectory control of flexible-joint space manipulator which considered gravity influence was studied in the paper. A progressive strategy was taken, firstly only considered gravity change and designed controller, then studied the control of space manipulator both considered gravity influence and flexible joint influence, finally extended the study to free floating situation. The main contents of this paper are as follows:Firstly, the rigid robot system considering gravity effect is studied, and designed a PD iterative learning control method, the convergence of the system is verified, and the simulation analysis is also carried out. The performance of the iterative learning controller is highlighted by comparing with PD controller.Secondly, the flexible joint model is added on the fixed-base controlled object system. A robust control strategy base on singular perturbation method was designed for the nonlinear system. The system order is reduced by using the singular perturbation method, then an adaptivce robust control algorithm was designed. The system stability is proved by Lyapunov method, and it is validated by simulation.Last, aimming at free-floating flexible-joint space manipulator considered gravity influence, an adaptive neural control algorithm in task space was designed based on singular perturbation theory. The stability analysis is presented, and the effectiveness of the scheme is verified by the corresponding simulation results.