Research On Composite Control Of A Free-floating Rigid-flexible Couplingredundant Space Manipulator

With the development of space and robot technology, the research on the free-floating redundantspace robot has attracted much attention. Besides a free-floating Rigid-flexible Coupling spacemanipulator has light weight, space operations and low lauch cost, which makes it become a hotresearch. The structural flexibility inevitably causes the elastic deflection and vibration. In this paper,we use a plane of free-floating rigid-flexible redundant space manipulator with three links for thestudy, and make further research for its modeling and control.Firstly, on the basis of the assumed modes method, Lagrange principle and momentumconservation, the dynamic modeling of a free-floating rigid-flexible redundant space manipulatorholding a rigid payload in a workspace is derived.Secondly, in modal space, the problems of the manipulator system’s trajectory tracking and thevibration suppression are discussed by using a composite control approach which combinesnon-singular terminal sliding mode control (NTSMC) and PID Integral sliding mode (PIDMC),respectively, with active vibration suppression control. Besides, these sliding mode control methodsuse fuzzy output instead of the symbol item, which smoothes the control signal, thereby inhibiting thechattering of the sliding mode control. Compared to common sliding mode control (SMC) andterminal sliding mode control (TSMC), these approaches not only can reduce the chattering of thesliding-mode control, but also can eliminate the singular phenomenon of the system’s control input. Inaddition, it can assure the trajectory tracking and the vibration suppression. Many space missions canbenefit from this modeling system, such as, autonomous docking of satellites, rescuing, and satelliteserving. Then the advantages and disadvantages of various control methods are analyzed, and wethrough simulation to experiment the effectiveness of control.Thirdly，the chaos dynamic model for Free-floating Redundant Space Robot is built, and, theminimal joint torque method is applied to implement the joint torque control, then we apply the robustcontroller to adjust its end-effector tracking control, based on robust control obtained angularacceleration inverse solution expression device, and convert them to the state equation. Then threechaotic recognition numerical methods are used to analyze this model. The numerical results showthat the dynamic system exhibits undesirable chaotic motion under the different system parameters.The linear and nonlinear state delayed feedback controllers are used to turn the chaotic into regular motion in the dynamic chaotic system. This study provides a helpful way to improve robot’s structureparameters and controller designing, also has an important theoretical and practical value. All theresearch work done in this thesis will surely provide foundations to the further research on morecomplex space robot systems in the future.Finally, we used GUI of MATLAB to construct the visual simulation platforms for describing thevisual movement of a free-floating rigid-flexible coupling redundant space manipulator.