A PID-Type robust controller design for industrial robots with flexible joints

In this paper, a robust control algorithm is proposed for industrial robots having flexible joints. A link with flexible joint is modeled as a two-mass system, which can be represented in terms of a cascade system. The controller is designed based on a recursive process for the cascade system and the robustness is obtained in each step of the design. Especially, we design the real control part having a PID-type control structure by including the integral action. The designed robust controller has capabilities of vibration suppression and robustness against disturbances and model uncertainties, e.g., perturbations due to the changes of the payload. The effectiveness of the designed controller is investigated through several simulations on a model of industrial robot and also shown through experiments using a HILS (Hardware In the Loop Simulation) system incorporating a small size manipulator.