Fault-Tolerant Control for Multi-Robotics System using Variable Gain Super Twisting Sliding Mode Control in Cyber-Physical Framework

This work is concerned with the development of an active fault tolerant scheme using second order sliding mode control for multi-robotics systems in the presence of actuator faults. The fault-tolerant controller based on conventional sliding mode control gives asymptotic convergence, less robustness, slower transient response and large amplitude of chattering that restrict its uses in real-time application. To overcome these issues, a nonlinear terminal sliding variable and a variable gain super twisting reaching law are employed to design nonlinear controller which ensures finite-time convergence and chattering attenuation. The closed-loop finite-time stability is analyzed using Lyapunov stability theory. The actuator faults information provided by the fault detection and diagnosis unit that is constituted by higher order sliding mode observer which will be used for reconfigure the controller parameters to retain the nominal tracking performance with high precision despite the actuator fault. Finally, the proposed methodology efficacy and effectiveness is tested using extensive simulation under both normal and faulty condition.