Sliding Mode Control of a Cable-driven Robot via Double-Integrator Sliding Surface

In this paper, robust control of a large cable-driven robot is presented (LCDR). In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motions. The mechanism has potentials for large scale manipulation and robotics in harsh environments. In this case study, sliding mode control via double integrator sliding surface is presented for tracking control of the robot against inevitable uncertainties. Double-integral sliding mode surface (PIID) is introduced to sliding mode controller to suppress the steady stated error in comparison with traditional one. Moreover, there is a common constraint on a LCDR making control problem more challenging. Since cables can only pull the end-effector, control algorithm must ensure all cable tensions are always positive. The asymptotic stability and robustness of the derived control law is proved using direct method of Lyapunov. Finally, the effectiveness of the proposed robust control scheme is demonstrated through simulations.