The operational space control applied to a space robotic manipulator

The stability properties of an operational space controller applied to a space robotic manipulator are investigated in this paper. It is shown that a major potential source of instability is the drive train dynamics in the joints of the manipulator. An analysis carried out with all normalized parameters shows that a nominally stable position control system may turn out to be unstable in practice. Problems arise also for force control, if proportional controllers are used. The analysis is supported by simulations obtained on a detailed dynamic model of the SPIDER arm, to be used in a space program on the International Space Station.