Decoupling Strategy for Position and Force Control Based on Modal Space Disturbance Observer

This paper extends the diagonalization method on the basis of the modal space disturbance observer (MDOB) for application to a multidegree-of-freedom (DOF) system. The aim of this method is to suppress the interference between the position and force control systems and realize a bilateral control system. The utility of the proposed method is experimentally verified by using a multi-DOF manipulator. It is confirmed that the MDOB-based decoupling method has better performance than oblique coordinate control. Conventional oblique coordinate control causes oscillation in cases where the modeling error is large and the cutoff frequency of an observer is not high enough to change the system dynamics. On the other hand, the MDOB-based decoupling method becomes unstable when the difference in mass is large.