Prescribed Performance Control for Pure-Feedback Systems with Unknown Control Coefficients

This paper investigates the performance control problem of pure-feedback systems with unknown coefficients. To tackle the substantial control issue in nonlinear systems with unknown control coefficients, we employ a specialized Nussbaum function. In addition, we have proposed a prescribed performance control approach grounded in robust techniques, Its objective is to guarantee the convergence of the output error to an arbitrarily small residual set within a predefined threshold. The results demonstrate that under the influence of the proposed control rate, the boundedness of all signals within the closed-loop system is ensured. Moreover, the prescribed steady-state and transient tracking performance is attained.