Research On Dynamic Modeling And Control For A Free-floating Flexible Dual-arm Space Robotic System

Over the past several years, the modeling and control of flexible space robots have attracted much serious attention. Compared with the conventional rigid robots, flexible robots have the potential advantages of lower energy consumption, large work volume and greater payload-to-manipulator weight radio. However, the structural flexibility inevitably causes the elastic deflection and vibration. As a consequence, the positioning and tracking performance of flexible robots will tend to be degraded. In this thesis, the dynamic modeling and control of flexible space robots are dealt with, and plenty of simulation tests have conducted to verify the effectiveness of the proposed methods.Firstly, on the basis of the assumed modes method, Lagrange principle and momentum conservation, the dynamic modeling of a free-floating flexible dual-arm space robot holding a rigid payload in a horizontal workspace is derived, and the trajectory tracking has been performed by the computed torque method. Secondly, for the elastic deflection and vibration of a free-floating flexible dual-arm space robot, an approach for LQ optimum vibration suppression is developed, and some simulation results conducted to verify the effectiveness of the proposed methods.Thirdly, the robust problem for trajectory tracking of a free-floating flexible dual-arm space robot is studied. A slow subsystem and a fast subsystem have been separated based on the singular perturbation method in which the sliding-mode control method and the PD control method are adopted in each subsystem respectively. Using this combined control method, the robot will track the expected trajectory perfectly and the flexible vibration will be suppressed effectively.Finally, to describe the visual movement of a free-floating flexible dual-arm space robot, two visual simulation platforms using MATLAB and OpenGL are constructed separately.