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In this paper, novel practical finite-time robust adaptive controllers are investigated for a 5-link single support phase (SSP) lower limb biped robot subjected to unknown physical and dynamical parameters, disturbances, and unknown input saturation. The developed adaptive approaches are based on a terminal sliding surface and a finite-time stability analysis to design controller and adaptation laws. The adaptive mechanisms deal with estimating unknown terms, the upper bound of the unknown term vector, or estimating the unknown limits of input saturation. Consequently, the proposed approach is applicable when the physical and dynamical parameters of the robot and the saturation input parameters are not known. In addition, the Lyapunov stability approach warranties that the tracking errors are robust finite-time uniformly ultimately bounded and provides the practical finite-time stability of the closed-loop system. Finally, numerical simulations are provided to show the feasibility, effectiveness, and performance enhancement of the proposed methods over state-of-the-art methods. [ABSTRACT FROM AUTHOR]

This paper investigates the finite-time robust tracking problem for a 5-DOF (degrees of freedom) upper-limb exoskeleton robot subjected to parametric uncertainties, unmodelled dynamics, and unknown human efforts. By developing the non-singular terminal sliding mode control approach, three innovative schemes of robust torques are proposed to steer configuration variables (angular displacements of joints) of the 5-DOF robotic exoskeleton to the reference trajectories within adjustable finite times. Based on mathematical analysis, it is proven that all suggested schemes of control inputs (input torques) accomplish and provide the mentioned tracking objective accurately. In addition, several new formulas (in the form of inequalities) are derived to determine and tune the needed finite times for achieving the tracking objective. Finally, three numerical examples are given to show the appropriate performance and the acceptable effectiveness of the proposed finite-time robust control schemes. [ABSTRACT FROM AUTHOR]