A passivity based stability analysis of disturbance observer based trajectory tracking control of nonholonomic wheeled mobile robot

This paper proposes a disturbance observer (DOB) algorithm to solve the trajectory tracking problem of a nonholonomic WMR in presence of external disturbances. To obtain a high performance trajectory tracking controller, a computed torque controller (CTC) is integrated into a kinematic controller by back-stepping technique. The disturbance observer as a part of the proposed controller estimates the external disturbances and cancel-out them. By decoupling the estimation errors from disturbances and its passivity property, it is demonstrated that the overall closed-loop system is asymptotically stable. Simulation results show that the performance of the CTC is significantly improved and the DOB achieves good ability of disturbance attenuation.