Position control of input-delayed mobile manipulator

This paper presents the design of a novel continuous robust controller for a nonholonomic mobile manipulator in the task space. The main objective of the designed controller is to compensate for the disturbance caused by an unknown time-varying input delay, while the end-effector of the manipulator accurately tracks the reference position trajectory. Notably, the designed robust controller is model-independent; thus, it does not rely on the nominal values of dynamic parameters. Moreover, the control development considers the uncertainties in the parameters of the mobile manipulator dynamics via an unknown time-varying additive disturbance in the dynamics. To guarantee the uniformly ultimate boundedness of the tracking error, the paper utilizes a novel Lyapunov-based stability analysis incorporating Lyapunov–Krasovskii functionals. The effectiveness of the designed controller for a mobile manipulator, composed of a differential drive mobile platform and a two-degree-of-freedom robot manipulator, has been confirmed via simulation results.