A Novel Adaptive Terminal Sliding Mode Tracking Control of Engine Electronic Throttle System Using an Enhanced Observer Under Composite Disturbances

This paper proposes a novel adaptive terminal sliding mode tracking control (ATSMC) strategy integrated with an enhanced super-twisting extended state observer (ESESO) for an engine electronic throttle system (EETS) operating under composite disturbances. First, a nonlinear dynamic model of the ETS is established by considering actuator nonlinearities, spring torque effects, friction uncertainties, and external load disturbances. Subsequently, an enhanced observer is developed to accurately estimate the lumped disturbance composed of model uncertainties, unmodeled dynamics, and external perturbations in real time. Based on the observer output, an adaptive terminal sliding mode controller is designed to achieve fast finite-time convergence while eliminating the requirement for prior knowledge of disturbance bounds. An adaptive law is introduced to automatically adjust the control gain, thereby reducing conservatism and mitigating chattering phenomena. Lyapunov stability analysis is conducted to rigorously prove the finite-time convergence and boundedness of all closed-loop signals. Comparative experimental studies demonstrate that the proposed method achieves superior tracking accuracy compared with conventional sliding mode and adaptive control approaches.