Full-State Event-Triggered Control for a Class of Nonlinear Systems with Input Delay

This paper addresses the tracking control problem for a class of uncertain strict-feedback nonlinear systems with input delay under communication constraints. The main difficulty is that the input delay degrades tracking performance, while full-state event-triggered transmission provides only intermittent state measurements, which are not directly compatible with the recursive backstepping design. To overcome this difficulty, an adaptive full-state event-triggered backstepping control scheme is developed. First, a Padé approximation is used to transform the delayed-input system into an augmented delay-free model. Then, an improved continuous-state estimator is introduced to reconstruct smooth surrogate state signals from the event-triggered measurements, thereby preserving the implementability of the recursive backstepping design. Based on the reconstructed states, an adaptive controller and an error-dependent event-triggering mechanism are designed to achieve practical tracking with reduced state transmissions. It is shown that all closed-loop signals remain bounded, the tracking error converges to an adjustable compact neighborhood of the origin, and Zeno behavior is excluded. Comparative simulation results further show that the proposed scheme reduces the triggering frequency and estimator-side computational burden compared with the high-order estimator-based scheme considered in the simulations, while maintaining satisfactory practical tracking performance.