Event-Triggered Prescribed Performance Control for SISO Uncertain Strict-feedback Systems with Unknown Control Directions

In this work, we consider the problem of designing event-triggered tracking controllers for uncertain strict-feedback systems with unknown control directions (UCDs). The proposed control scheme is static, and requires no hard calculations, analytic or numerical, to produce the control signal. The event-triggered mechanism applied on the controller-to-actuator side relies on the so-called relative threshold strategy. No prior knowledge or approximation structures regarding the system nonlinearities are required and no high-order derivatives of the desired output trajectory are incorporated in the controller design. Yet the enforcement of prescribed performance bounds on the output tracking error in terms of steady-state accuracy and convergence rate is guaranteed. Simulation results clarify and verify the theoretical findings.