Research On Dynamics And Control Of Space Flexible Manipulator In Large Overall Motion

With the development of space technology, space manipulator is used more and more widely. Under the premise of relationship that space flexible manipulator system surrounds the target spacecraft, this paper does research on dynamics and control of space flexible manipulator system with carrier’s position and attitude are under control.Firstly, dynamic model of space flexible manipulator system is derived on basis of hybrid coordinate method and Lagrange equations in the inertial coordinate. The deformation of flexible manipulator is described by assumed mode method and finite element method respectively. Then the system dynamic model is modified according to dynamic equations of space flexible manipulator system surrounding the target spacecraft. In order to capture the target spacecraft, trajectories of position and attitude of the carrier and joint angles of manipulator are planned using inverse kinematics of space flexible manipulator system and cubic spline interpolation. Controller is designed based on singular perturbation method. Finally, the simulation results show that the controller can realize joint angular tracking control and suppress vibration of flexible manipulator.To reveal the coupling effect between coupled deformation of midline and large overall motion on vibration of flexible manipulator, this paper first studies one-dimensional cantilever beam in large overall motion. Simulation results show that since coupled deformation of midline is ignored in dynamic model derived by hybrid coordinate method, when angular velocity of cantilever beam greater than first-order natural frequency of its lateral vibration, negative stiffness occurs in dynamic model, longitudinal and lateral vibration of cantilever beam diverges. For dynamic model with coupled deformation of midline, vibration of cantilever beam is stable, which is identical with actual situation. For space flexible manipulator system, during the process of capturing target spacecraft angular velocity of manipulator is much smaller than first-order natural frequency of its lateral vibration, so simulation results of dynamic model with and without coupled deformation of midline are identical. Deformation of manipulator is described more accurately in dynamic model with coupled deformation of midline, and this kind of model can be adapted in high speed rotation in future.To further verify the correctness of derived dynamic model and designed controller, the space flexible manipulator virtual prototyping model is established by ANSYS and ADAMS, and controller is designed in MATLAB. The ADAMS-MATLAB united simulation is conducted with interactive interface. The results of united simulation are highly consistent with the MATLAB simulation results, which verifies the correctness of derived dynamic model of space flexible manipulator system and indicates the effectiveness of designed controller.