Finite-time robust trajectory tracking control for robotic manipulator under actuator nonlinearities and parametric uncertainties

This paper studies effective trajectory tracking control of a robotic manipulator in the presence of dead zones in the input actuator and uncertainties in the system. Initially, we model the actuator dead zone as an unknown dynamic uncertainty and combine it with external disturbances and system uncertainties. Subsequently, we introduce a third-order sliding mode observer (TOSMO) to discern the system perturbations. Using the estimates provided by the TOSMO, we design a new finite-time (FT) convergent integral sliding mode controller. A key feature of the proposed control structure is the reduction of control input chattering despite the presence of input nonlinearity. Furthermore, we explicitly compute the convergence regions of both the observer and controller in terms of design parameters. In addition, we establish the FT convergence of the system states, state errors, and observer estimation errors through Lyapunov stability analysis and derive the explicit expression for convergence time. Finally, comprehensive comparative simulations and results showcase the efficacy of the proposed control scheme for trajectory tracking control of robotic manipulators.