Path Planning Research Of The Free-Float Space Robot

Space robot will play an important role in future hazardous and complicated space activity, such as assembly of the space station,target capture and so on, therefore the research of space robot has become a research hotspot of aerospace technology all over the world. Free-floating Space Robot is one kind of the space robot that has the characteristics of attitude disturbance, kinematic redundancy and noholonomic because the position and the attitude are not controlled. This thesis studied on the problems of kinematic, dynamics, trajectory planning and simulation of free-floating space robot. The main contributions of the thesis are as follows:1.Research on the kinematic modeling method and dynamic modeling method. On the basis of the multi-body dynamics theory and spacecraft attitude dynamics theory, the kinematic model is derived according to the geometric relationship and momentum conservation/ angular momentum conservation, the dynamic model is presented with the Newton-Euler method.2.Research on the Cartesian space path-planning algorithm and joint space path-planning algorithm. In the Cartesian space path-planning algorithm, firstly, according to constraint equation of the end-effector, the velocity trapezoidal method is proposed to plan the end-effector velocity, then the differential kinematical equations is used to plan the motion of the space manipulator. In the joint space path-planning algorithm, joint interpolation function is proposed to accomplish the trajectory planning according to the joint constraint equation.3.Research on the path-planning algorithm to minimize the base attitude disturbance. Due to the characteristics of base attitude disturbance, the path-planning algorithm based on genetic algorithm is proposed to minimize the attitude disturbance. The joint trajectories are parameterized by sine function, then the optimal parameters are solved using the genetic algorithm.4. Research on the dynamic singularity of the space robot. Dynamic singularity is not only the functions of the kinematic structure of the terrestrial fixed-based manipulator, but also depend on the mass and inertia distribution in the Cartesian path planning. In this thesis a practical approach is proposed to avoid the dynamic singularity, which transforms it into kinematic singularity avoiding problem. The ground jacobian is simplified to reduce calculation. Finally, singularity avoidance is achieved by the using quadratic programming.5.Research on the simulation technology of the space robot. The visual simulation system of the FFSR based on 3D simulation technology is developed, which is composed of 3D modeling module, forward kinematics module and path-planning module. The real-time 3D simulation system visualizes the path planning process intuitively. As for the typical task of the space robot, the target acquisition, target moving and reposition experiment are designed. Experiment results verified the integrated performance of the space robot simulation system.