Designing Robust Finite-Time Nonlinear Torques for a n-DOF Robot Manipulator with Uncertainties, Sector and Dead-Zone Nonlinearities

In this paper, a complete dynamical model is presented for an uncertain -DOF robot manipulator containing description of sector and dead-zone nonlinearities. Next, robust finite-time tracking problem of desired trajectories is declared and formulated for the aforementioned robot manipulator. By defining innovative nonlinear sliding manifolds and developing the nonsingular terminal sliding mode control, several types of input torques are designed to exactly reach configuration variables of robot's joints to desired paths within the finite times in the presence of uncertainties, sector and dead-zone nonlinearities. By utilizing some applicable lemmas and well-known inequalities, for each class of the proposed input torques, the global finite-time stability of the closed-loop robot system is proven analytically. Also, several new formulas are extracted for determining the convergence finite times of the closed-loop system. These formulas demonstrate that mentioned times are dependent on robot's initial conditions and optional parameters of the suggested torques. Finally, by using MATLAB software, all classes of the designed torques are numerically simulated onto the SCARA industrial robot manipulator and obtained results show the acceptable performance of the suggested control scheme.