Tracking control of flexible joint manipulators using only position measurements

摘要

Abstract A dynamic feedback controller will be proposed to treat the trajectory tracking control problem of robotic manipulators with flexible joints that use only position measurements on the link and motor sides. Previously published results for the tracking control problem without velocity measurements address only the rigid robot design. Moreover, these results are based on a full-order observer whose dimension is equal to the dimension of the robotic systems. In contrast, our solution can be applied to treat the robotic systems with flexible joints. It does not require any restriction on the joint stiffness. The proposed controller is based on a reduced-order observer which is constructed only to estimate the velocity signal and whose dimension is half of the dimension of flexible-joint robotic systems. We shall show that the resulting closed-loop error system is locally exponentially stable with an arbitrarily large region of attraction. The convergence rate can be arbitrarily pre-assigned and the attraction region not only can be pre-assigned but also can be explicitly constructed. Moreover, as the unknown uncertainties are concerned, the robustness of the closed-loop system is also discussed. Finally, simulation results are included to demonstrate the tracking performance.