Sensory feedback control for space manipulators

The positioning control problem of the end tips of space manipulators which have no fixed bases is investigated. According to the momentum-conservation law, the system is represented by a nonholonomic model. Thus, the conventional control method for industrial robots, based on a local feedback at each joint, is not applicable when the end tip must be positioned at a floating target. For this problem, the sensory feedback control scheme is based on the artificial potential defined in the sensor coordinate frame. The generalized Jacobian plays an important role in determining the control torque of each joint from the data of the external sensors. This scheme is simple, and the stability of the system is strictly assured. The approximate Jacobian, which needs less computation and less parameter identification, is shown to work well