Control Of Free-floating Space Robot With Elastic Base

With the increasing development of space technology, countries all over the world take much attention to the space resources. Space robot substituting or assisting astronaut to complete the job in space becomes necessary as result of the bad space environment. In order to expand the active scope of the free-floating robot on space station, manipulator is mounted on a rail. Result of interaction between manipulator and base, the vibration of rail has an big impact on trajectory control and other parts of the station result of interaction between manipulator and base. And the vibration will be difficult to attenuate in outer space environment. So trajectory tracking control of free floating space-based manipulator with elastic base is discussed in this paper.Because of preciousness of the space fuel, space robots are usually operated in base’s position-uncontrolled mode. While in order to ensure the communicate device working properly, the space station requires to maintain a certain attitude angle. Therefore, the free-floating space-base robot with position-uncontrolled and attitude-controlled is studied in this paper. According to the geometric feature the generalized Jacobian matrix is derived. And the Lagrangian method and the momentum conservation are adopted in building the dynamic equations. Then the kinematics and dynamics of the space robot are analyzed to prepare for control scheme.Sliding-mode control is designed for free-floating space robot with elastic base, which has strong robustness and high precision. Sliding-mode control apply to both joint space and inertial space trajectory control. The simulation results show that vibration of elastic-base has big impact on trajectory control result of no vibration suppression.Trajectory tracking control and vibration suppression problems of free floating space-based manipulator with elastic base are discussed base on the singular perturbation theory. Joint torque output control law is designed in order to meet the control objectives of trajectory tracking control and vibration suppression instead of installing another driver, which can reduce costs. The simulation results show the advantage of the proposed control scheme.It is difficult to get the exact dynamic model of space robot in reality result of the highly nonlinear, strong coupling and uncertainties(such as uncertain load, friction and external disturbance) of space robot. Therefore, control of elastic-base free-floating space manipulator with model error and external disturbance is discussed in this paper. The simulation results show that the proposed control scheme is feasible.