Control For Trajectory Tracking And Vibration Suppression Of A Free-floating Space Flexible Manipulator

Over the past several years, human activities are very frequent in space. Space flexiblemanipulators which can replace astronauts’ work have been widely applied. However, the flexiblemanipulators will produce elastic deformation which can affect the operation accuracy of the arm andthe stability of the entire manipulator system. In this thesis, the dynamic modeling and control offlexible space manipulators are dealt with, and plenty of simulation tests have conducted to verify theeffectiveness of the proposed methods.First, on the basis of the assumed modes method, Lagrange principle and momentum conservation,the dynamic modeling of a free-floating space flexible manipulator with a rigid load on-orbit isderived.Second, for the highly coupled nonlinear dynamic model,(1) in the case of without decoupling, PDcontrol, integral control, and optimal control are adopted. Using this combined control method, thesystem can track the expected trajectory accurately and its flexible vibration can be suppressed.(2) aslow subsystem and a fast subsystem are separated based on the singular perturbation method inwhich a fuzzy terminal sliding mode control method and a Backstepping control method areadopted in each subsystem respectively. Using this combined control method, the system can track theexpected trajectory accurately and its flexible vibration can be suppressed. Finally, the two methods’advantages and disadvantages are compared.Third, the dynamic modeling of a free-floating space flexible redundant manipulator is derived.Then, on the basis of minimum joint torque method, the manipulator’s joint acceleration inversesolution is derived. The simulation result shows that the self-motion of free-floating redundant spacemanipulator is chaotic in the dynamic system. Then, the delayed feedback chaos control is proposed,which suppresses a free-floating redundant space manipulator’s chaotic motion with dynamic control.Finally, to describe the visual movement of a free-floating flexible space manipulator, visualsimulation platform using MATLAB is constructed separately.