Abstract: The inverse dynamics of a space manipulator is discussed in this paper. It is shown that as the result of the nonholonomic behavior of the system,the Liapunov's method with the joint angles as variables is infeasible in the practice,owing to the theoretical incorrectness and the appearance of dead point in computation. The Liapunov's method using the configuration of the payload as variables is suggested,and a numerical example is given. The improved method of path-planning can ensure the asymptotic stabili...