Adjustable transient performance for unknown nonlinear systems via control gain selection: Application to tower crane systems.

This paper proposes a modified adaptive backstepping method with a control gain selection guideline for unknown nonlinear systems, focusing on adjustable transient performances. Unlike conventional backstepping methods that cancel linear cross terms, the proposed approach retains these terms to obtain a symmetric state matrix for the linearized closed-loop system. Based on this structure, a novel control gain determination method is developed to select control gains for achieving a desired settling time while effectively attenuating overshoot. Compared with conventional trial-and-error tuning, the proposed method improves tuning efficiency. Moreover, the potential solvability difficulties of optimization-based pole-placement methods are avoided. Numerical examples with different desired settling times demonstrate adjustable settling time and overshoot attenuation. Simulations and experiments on a tower crane platform further validate the proposed scheme and demonstrate its advantages compared with existing control methods.