Robust Control using Recursive Design Method for Flexible Joint Robot Manipulator

Flexible joint robot manipulators can be decomposed into two cascaded subsystems, a series connection of robot link dynamics and joint dynamics. For these flexible manipulators, we propose the robust controller using a recursive design method. The recursive design procedures are constructive and contain two steps. First, a fictitious robust controller for the robot link dynamics is designed as if the link dynamics had an independent control. As the fictitious control, a nonlinear H_infin control using the energy dissipation is designed in the sense of L₂-gain attenuation from the disturbance caused by uncertainties to performance. Second, a real robust control is designed recursively by using a Lyapunov´s second method. The designed robust control is applied to a 2 DOF robot manipulator with joint flexibilities.