The Collision Dynamics Analysis Of Space Flexible Manipulator When Performing On-orbit Capture Task

In recent years, with the continuous development of space exploration, space manipulator has been widely used in the space on-orbit operation because of its superior movement and high load capacity. As space manipulator has the characteristics of slender ann and low stiffness,its flexible characteristic of the ann is obvious. Impact force will generate during target capture/transfer tasks when contact happens, and it will not only cause the disturbance of base attitude, deformation and vibration of the flexible arm may also be exacerbated, thus affecting the stability of the end-effector and operation accuracy of the whole system, and can even make the target escape. Therefore, it is urgent to study the related technologies of target capture/transfer for space flexible manipulator,which has important theoretical significance and application value for the development of space technology.Aiming at the target capture/transfer tasks of space flexible manipulator, this paper mainly focuses on the modeling of space flexible arm, imulti-body collision dynamics modeling, as well as trajectory tracking and vibration suppression of space flexible manipulator. The effectiveness of proposed theory is verified through numerical simulation and experiment. The main research work is as follows:Firstly, the kinematics and dynamics modeling of space flexible manipulator are carried out under the consideration of arm multidimensional flexibility. Based on cantilever beam model and the assumed mode method, the flexible ann model is set up considering not only the flexible deformation in the motion plane, but also the one in the plane perpendicular to the motion plane. And then the forward kinematics modeling is established based on DH method, and the Jacobian matrix of flexible arm modal is established by vector product method. After solving the kinetic and potential energy, the dynamics model of space flexible manipulator is obtained and its response equation for joint free, joint lock and joint control is set up respectively.Secondly, the dynamics modeling of single flexible rod is studied and its collision response is analyzed. Based on Newton's second law and Euler equation, the universal dynamic equation of the single body is derived. The model of non center collision of single body is established by combining Hertz damping force model. Based on Lagrange equation and Hertz damping force model, the collision dynamics model of a single flexible rod is derived. The validity and accuracy of the collision force model and the flexible arm model considering arm multidiimensional flexibility are proved by MATLAB numerical simulation and ANSYS/ADAMS software simulation.And then, the related theory of capture tasks performed by space flexible manipulator is studied, including trajectory tracking, vibration suppression, multi-body collision dynamics modeling and configuration optimization. Based on the modeling of multi-body collision dynamics,space manipulator's configuration is optimized by equivalent mass method. The nonlinear decoupling feedback control and LQR method are adopted to achieve the trajectory tracking and suppress the residual vibration during the capture process.Finally, the ground experiment is carried out to verify the validity of proposed collision theory of space manipulator. Through the analysis of experimental results, the expected results are obtained, and thus the validity of multi-body collision dynamics model is verified.