Hybrid Control of Cable Robots with Elastic Cables

In this paper a modified adaptive robust composite control scheme for fully-constrained cable-driven robots with elastic cables is presented here. At first, an adaptive control algorithm based on sliding mode control method is introduced for rigid robots using internal force concept to ensure that all cables are remained in tension through the whole workspace. Then, the dynamic equations are turned into singularly perturbed form to develop the adaptive controller of rigid robots to be used for robots with elastic cables. To improve the stability and robust performance of the system as an achievement of the paper, a correction term is added to the adaption law of rigid robots and the stability analysis of the system is conducted using the Lyapunov theory. Finally, while the simulation results are given for intended robot with elastic cables, performance of the proposed algorithm against the uncertainty of dynamic parameters is proved and by comparing the performance of the proposed control scheme in this paper with those related to the initial robust adaptive controller a remarkable improvement in the accuracy of the desired path tracking confirmed.