Control strategy for a free-flying space manipulator

The exploitation of autonomous robot systems will be a key feature in forthcoming space missions. This paper describes the methods used to solve the inverse kinematic problem of a nonredundant robotic arm mounted on a free-floating spacecraft, so that the end-effector follows its positioning path in the least possible distance, with minimal disturbance of spacecraft attitude. A priority sliding control strategy is used, activating and relaxing the nonholonomic constraint due to the conservation of angular momentum, since with only the forces of the joints acting on the system, the attitude of the main body cannot be controlled using a generalized Jacobian approach. The advantages of this strategy are simplicity and rapidity of path planning, with minimal waste of energy for body repositioning. An application to the measurement system of both nonholonomic and holonomic constraints is also presented for such robots. Simulation results are described. Experiments with a planar air-floating model are in progress.