Nonlinear bang-bang impact control for free space, impact and constrained motion: multi-DOF case

This paper presents stability analysis and experimental results of the nonlinear bang-bang impact controller for multi-degree of freedom robot manipulators. Stability conditions have been derived based on the analysis in L_∞ ⁿ space and their physical interpretation has been given. The analysis shows that the stability of nonlinear bang-bang impact control depends on sampling time and the accuracy of inertia estimation. Stability is enhanced with the decrease of changes in the Coriolis, centrifugal, and disturbance forces. The stability conditions are verified by experiments. Experimental results show that the nonlinear bang-bang impact controller performs a seamless contact manipulation that involves impact with only one control algorithm and the same gains in all three contact modes. It is also shown via experiments that the nonlinear bang-bang impact control is robust to disturbance and environmental changes.