Event-triggered tracking control of strict-feedback nonlinear systems with output constraints via an adaptive...

This paper develops an event-triggered adaptive tracking control scheme for strict-feedback nonlinear systems with output constraints. Current methods remain conservative and lack mechanisms for controllable constraint deactivation. To meet both safety and performance requirements, an adaptive constraint-handling mechanism (ACHM) is designed to modulate the constraint effect based on the system state and autonomously deactivate it once the tracking error enters a state-dependent safe region. A state-dependent shift function characterizes the deactivation process and ensures a smooth, analytically tractable transition between constrained and unconstrained phases. Embedding this function into an error-transformation framework yields a self-regulating constraint region that tightens for large errors and relaxes as the error decreases, reducing conservatism without compromising safety. Moreover, a dynamic event-triggered mechanism (DETM) with an error-dependent threshold is incorporated into the adaptive control strategy, enhancing transient responsiveness and significantly reducing communication load. A simulation study on a spring-mass-damper system verifies the effectiveness and advantages of the proposed method.