Dynamics And Control Of Space Flexible Robot In Grasping And Transfering Target On Orbit

With the development of space exploitation, the application of the space robot became more important and popular. Because of the coupling between the base and the manipulator, the dynamic singularities and the impact in operation, the operational dynamics and control of space robot are more difficult. This thesis focuses on the impact in space robot capturing target, the structure variant dynamics, the stabilization control after grasping, tracking control during transfer the target with unknown parameters, and also the vibration suppression in the positioning control.The space flexible robot is typical space multibody flexible system. Because of floating base, flexible arm and impact force, the dynamic analysis and computation become quite complicated. Spatial operator algebra with high computational efficiency is introduced for the dynamic real time simulation and controller design, and the software of flexible multibody dynamics is implemented based on Lagrange analytical theory, both are compared to the commercial dynamic software for validation.When space robot captures the target, the dynamic grasping area is created for describing the impact between the grabbing device and target gripe. Then the joint active damping and base attitude control is applied, and the ideal grasping strategy is brought forward to reduce the impact during grasping. Provided that the inertia parameters of target may be unknown when capturing, the estimation based on momentum conservation theory and least square method is applied during grasping procedure, which is significant for target capturing, and can assist grasping control and decision. The stabilization control during the grasping is researched. The grasping soft-hard characteristic is found by using sliding control in joint: the hard grasping can keep the stiffness, while the soft grasping can reduce the impact to the base. The reactionless null space and optimal feedback control are introduced for the reactionless vibration suppression control that can control the vibration efficiently with less influence to the base attitude.After grasping, the variant structure dynamics is analyzed, and the stabilization control is applied during the whole procedure. When the space robot finishes capturing the target, the grasping characteristics of the arm will change, and the frequency may reduce notably, making tracking and vibration control more difficult. The dynamic and control of the redundant manipulator is analyzed, and the pseudo-inversion of Jacobian matrix is illustrated and computed efficiently based on Spatial Operator Algebra. Then, the tracking control in the base workspace of flexible redundant robot is applied, and the redundant optimization and optimal feedback control is used for vibration suppression. Then the augmentation approach is introduced for tracking control in the inertial operational space with vibration suppression. The adaptive control is applied to deal with the target with uncertain inertia parameters, and the sliding surface can reduce the static errors and disturbances caused by flexible arm and unknown target.