A robust linear controller for flexible joint manipulators

In this paper a new and completely linear algorithm is proposed for composite robust control of flexible joint robots. Moreover, the robust stability of the closed loop system in the presence of structured and unstructured uncertainties is analyzed. To introduce the idea, flexible joint robot with structured and unstructured uncertainties is modelled and converted into singular perturbation form. A robust linear control algorithm is proposed for the slow dynamics and its robust stability conditions are derived using Thikhonov's theorem. Then the robust stability of the total system considering the proposed composite controller is analyzed, and sufficient conditions for robust stability of system is obtained. Finally the effectiveness of the proposed controller is verified through simulations. It is shown that not only the tracking performance of the proposed controller is very suitable, but also the actuator effort is much smaller than previous result.