Nonholonomic path planning of space robots

Abstract

The authors discuss the nonholonomic mechanical structure of a space robot and its path planning. The conservation of angular momentum works as a nonholonomic constraint, whereas the conservation of linear momentum is a holonomic one. In this framework a vehicle with a 6-DOF (six-degree-of-freedom) manipulator is described as a nine-variable system with six inputs. This implies the possibility of controlling the vehicle orientation as well as the joint variables of the manipulator by actuating the joint variables only if the trajectory is carefully planned, although both the variables and the trajectory cannot be controlled independently. In planning a feasible path, a system than consists of a vehicle and a 6-DOF manipulator can be treated as a 9-DOF kinematically redundant system. The nonholonomic mechanical structure of the space vehicle/manipulator system is shown, and a path planning scheme for nonholonomic systems using Lyapunov functions is proposed.<>