Singularity-consistent teleoperation techniques for redundant free-flying robots

Abstract

We analyze the performance of a kinematically redundant, 7 DOF free-flying robot under Cartesian velocity telecontrol. It is shown that the system can be easily destabilized when conventional pseudoinverse redundancy resolution is used, which is due to the presence of algorithmic singularities. A singularity-consistent (SC) solution to the problem is proposed that guarantees stability throughout the feasible motion range. Two SC redundancy resolution techniques are compared: one based on the pseudoinverse of the generalized Jacobian, and another one, based on null space minimization of base attitude disturbance. It is shown that although null space minimization outperforms the pseudoinverse approach in terms of disturbance minimization, this is done at the expense of spurious arm motions. And the gain from the minimization is not sufficient to diminish the disadvantage. Thus, it is concluded that SC pseudoinverse control is a very reliable way of redundancy resolution for a teleoperated arm in space.