Observer‐Based Active Fault‐Tolerant Sliding Mode Control for Fully‐Constrained CDPRs

This study introduces an active fault‐tolerant sliding mode control (AFTSMC), designed explicitly for fully‐constrained cable‐driven parallel robots (CDPRs). The approach integrates real‐time fault estimation through a nonlinear observer, establishes a synchronization error and employs an SMC to enhance the robustness and operational performance amidst various faults. The proposed approach is designed to address different fault types, including loss of effectiveness and lock‐in‐place faults that may arise in CDPR actuators. To develop the idea, at first, a comprehensive dynamic model of the CDPR, including fault modelling, is constructed, and an extended‐state observer is employed to estimate the system states and facilitate fault detection, whose estimated information is utilized in the control law to compensate the fault effects. The convergence of the observer is assessed using the Lyapunov method. Next, to demonstrate the effectiveness of the proposed control method, some simulations are performed on a 3 degrees of freedom CDPR featuring a redundant cable configuration. The findings illustrate the capability of the AFTSMC method to ensure accurate trajectory tracking, even in the presence of simultaneous faults and disturbances, highlighting its potential to enhance the reliability and fault tolerance of CDPR systems.