Event-triggered sliding-mode control for underactuated Euler–Lagrange systems subject to external disturbances

This paper presents an event-triggered sliding-mode control method for underactuated Euler–Lagrange systems. The time-delay estimation technique is applied, rendering it model-free and robust against parametric uncertainties and external disturbances. A time-varying gain is incorporated into the sliding variable to enhance control performance for underactuated states. Furthermore, an event-triggered mechanism is employed to reduce communication frequency without compromising control accuracy. Rigorous stability analysis establishes the exponential convergence of the sliding variable, uniform ultimate boundedness of the tracking errors, and the exclusion of Zeno behavior. The effectiveness and robustness of the proposed scheme are validated through numerical simulation and physical experiment on an overhead crane system.