Adaptive iterative learning control for nonlinearly parameterized systems with unknown time-varying delay and unknown control direction

This paper proposes a new adaptive iterative learning control approach for a class of nonlinearly parameterized systems with unknown time-varying delay and unknown control direction. By employing the parameter separation technique and signal replacement mechanism, the approach can overcome unknown time-varying parameters and unknown time-varying delay of the nonlinear systems. By incorporating a Nussbaum-type function, the proposed approach can deal with the unknown control direction of the nonlinear systems. Based on a Lyapunov-Krasovskii-like composite energy function, the convergence of tracking error sequence is achieved in the iteration domain. Finally, two simulation examples are provided to illustrate the feasibility of the proposed control method.