Active Sliding Mode Fault Tolerant Control of a Fully-Constrained Planar Cable-Driven Parallel Robot

Abstract

Cable-Driven Parallel Robots (CDPRs) have gained attention for about five decades due to their unique features. Cable robots have the advantages of both serial and parallel robots while avoiding their structural limitations. Using cables instead of rigid limbs in parallel robots has presented novel control challenges to researchers. Furthermore, ensuring safety and reliability in their operation is one of the most significant challenges in the cable robot control. This paper addresses challenges in CDPR control, focusing on safety, reliability, and fault detection. A dynamic model is proposed using a state-space structure, enabling the separation of desirable and undesirable parameters. An extended state observer is utilized for fault detection in the presence of dynamic uncertainties, disturbance, and actuator faults in the CDPR system. A kinematic relationship is defined to achieve fault-tolerant control and synchronization. A Sliding Mode Control (SMC) algorithm is developed to compensate actuator faults effectively, particularly partial actuator loss. The algorithm ensures non-negative cable tensions using the internal force technique and is proven stable through Lyapunov analysis. Simulation results validate its fault detection and reference trajectory tracking effectiveness despite actuator faults.