Study On Motion Planning Approach For Free-floating Space Manipulator System

The space manipulator which has a broad application in space tasks such as spaceassembly and repair, is one of the critical technologies for the foundation of our spacestation. Aiming to solve the motion planning problems of space flexible manipulator,this dissertation studies the approaches of motion planning for minimum disturbance tothe carrier’s attitude, vibration reduction and optimal multiple-objective. The mainresults achieved in this dissertation are summarized as follows.Dynamic model of the free-floating flexible space manipulator system isestablished, and the dynamic model is validated using ADAMS software. Then, theerror brought by modal truncation and the influence of free-floating carrier on theelastic deflection are also discussed. These works provide the foundation for the motionplanning of manipulator system.An improved motion planning approach of zero-disturbance to the carrier’s attitudein point-to-point manipulation is proposed. The zero-disturbance motion planningproblem is transformed into a non-linear parameter optimization problem. Combiningthe global search ability of genetic algorithm and the high convergence rate ofsequential quadratic programming, a pipelining approach containing the initial guess isproposed to solve the zero-disturbance motion planning problem. The globalconvergence ability and effectiveness of the pipelining approach are testified by solvingthe zero-disturbance motion planning problem of planar and spatial manipulator. Andthen, a motion planning approach based on translational zero-disturbance curves is putforward to improve the convergence ability of non-linear parameter optimizationapproach. Another approach for planning the speed along the zero-disturbancetrajectory is proposed, by which the optimal joint speed and manipulation time areobtained under the constraints of joint torque.A hybrid optimal approach for motion planning of vibration reducing inpoint-to-point manipulation is proposed. Considering the specialty of motion planningproblem in vibration reducing, a hybrid optimal approach combined the computingefficiency of Gauss Pseudospectral Method (GPM) and the accuracy of Direct ShootingMethod (DSM) is proposed. The effectivity of the hybrid approach is validated bysolving the motion planning problem of global vibration reduction and residualvibration reduction. Considering the uncertainty of initial state of flexible manipulator, amotion planning model involved the robustness performance index of residual vibrationis put forward, and the optimal motion for robustness performance index is obtained.A motion planning approach for trajectory tracking is studied. A motion planningapproach based on self-motion to minimize the attitude disturbance is presented. Thefeasibility of the proposed approach is validated in comparison with a planning method based on the pseudoinverse of generalized Jacobian matrix. Using the planningapproach based on self-motion and the hybrid approach employing GPM and DSM, themotion planning problem of vibration reduction in trajectory tracking manipulation canbe solved quickly and stably.An optimal multiple-objective motion planning approach of space manipulatorsystem is developed. The motion planning is proposed to take account of thedisturbance to the carrier’s attitude, the elastic vibration, manipulation time, and so on.Considering the specialty of optimal multiple-objective problem, the physicalprogramming method is used to convert the multiple-objective problem to asingle-objective one which expresses the designer’s preference, and is solved using thehybrid approach. The Pareto optimality of the solutions obtained by physicalprogramming is testified by NSGA-ΙΙ. And then, the designer preferred solutions tomultiple-objective motion planning problems of different manipulations are obtained.This dissertation proposes the motion planning approaches for minimumdisturbance to carrier’s attitude and vibration reduction, and also explores the optimalmultiple-objective motion planning model and approaches. Some developments intheories and methods have been attained. This study is closed to the application of spacemanipulators, and the presented motion planning approaches have a significant potentialapplication for the development of our space manipulator.