Fractional order adaptive sliding-mode finite time control for cable-suspended parallel robots with unknown dynamics

Adaptive fractional order finite time sliding mode control (AFFSMC) of cable suspended parallel robots (CSPR) in the presence of model uncertainties is studied in this paper. To do this, a fractional order sliding surface is first designed and then, considering that because of heavy lumped uncertainties there is not any information about the robot dynamics, a finite time adaptive sliding mode controller is proposed to ensure finite time stability with fast convergence of cable robot states to a desired trajectory. In this method, the unknown dynamic parameters vector of the cable-suspended parallel robot is estimated via a stable adaptive law. Using the dynamic model of cable robot, stability analysis of the closed-loop system along with the finite time convergence of robot end effector have been performed using the developed Lyapunov theory. The simulation results are presented to express the accuracy of the control law and a comparison with the ordinary integer sliding mode control is also presented.