Free Floating Space Robot Trajectory Planning

With the development of astronautics technology, space robot will play an increasingly important role in future space activities. The space robot which consists of spacecraft base and manipulators mounted on base can take the places of astronauts to work on orbits. Working in the free-floating mode, the fuel used to control the spacecraft location and orientation can be saved and long the life of space robot. In this paper, kinematics and dynamic modeling,trajectory planning of free-floating space robots are studied.Based on the concept of "augmented body vector" in dynamics of multi-rigid body theory, the kinematics model are derived by analyzing the geometry relationship of the system motion, momentum and angular momentum conservation equations, and then using the kinetic energy expression and Lagrange equation, the dynamic model is established. The work discussed above is the theoretical foundation of trajectory planning for free-floating space robot.Considering the problem of Free-Floating space robot trajectory planning, by analyzing the system nonholonomic characteristic, a trajectory planning scheme based on polynomial interpolation and Particle Swarm Optimization is proposed. Using this method, the attitude of base and position of end-effecter can be adjusted at desired condition at the same time.The manipulator movement is drived by the actuating motor which discharges the system electrical energy. To save the system electrical energy, a minimum-torque trajectory planning algorithm is proposed. Numerical results show that the manipulator torques are optimized with the system condition arriving at the desired condition.Finally, a trajectory planning algorithm based on Constriction Factor Particle Swarm Optimization is presented for free-floating space robot to minimize the spacecraft disturbance due to the motion of manipulator. Simulation results demonstrate that with accomplishing the space robot attitude mission, the spacecraft disturbance reduces to the least.