Extension of High-Gain controllable systems for improved accuracy

A PI-controller like extension structure for high-gain controllable nonlinear systems with known relative degree is investigated. The extension ensures accurate asymptotic tracking for plants with proportional steady state characteristic. It can be guaranteed that the control error converges to zero. The introduced structure extends the original plant to an auxiliary system, which is still controllable with high-gain based concepts. Funnel-control, a sophisticated high-gain based time-varying control strategy, is re-examined to illustrate the advantages of the extension. The extension neither affects the controllability of the original plant nor requires a supplementary (adaptive) controller design, but improves the achievable control performance by absolute accuracy