Robust non-singular fixed-time sliding mode control for robot manipulators: Franka robot arm

Modern robotic applications demand precise trajectory tracking, which is particularly challenging due to the nonlinear dynamics, model uncertainties, and external disturbances inherent in robotic manipulators. Robust control strategies, such as Sliding Mode Control (SMC), have proven effective in addressing these challenges. Advanced variants, including finite-time and fixed-time SMC, offer the added advantage of ensuring stabilization within a predefined time frame. This paper proposes various strategies for the Franka robot, ensuring global fixed-time convergence of the closed-loop system with a singularity-free design and the settling time estimation is independent of initial conditions. A non-singular terminal sliding surface is utilized to achieve precise trajectory tracking, enhanced robustness to external disturbances, and simplified implementation. The effectiveness of the proposed methods is validated through realistic simulations of the Franka robot.