Nonlinear recursive gain asymptotic tracking controller design for hydraulic turbine regulating systems

This paper focuses on the nonlinear asymptotic tracking control for a hydraulic turbine regulating system (HTRS). The proposed control approach combines a recursive gain control scheme with an adaptive technique to achieve asymptotic tracking. An important characteristic feature of the proposed controller is the incorporation of a smooth function with a time-varying function that is integrable and positive. This function provides the developed controller with sufficient power to achieve asymptotic tracking, whereas the recursive gain control alone can ensure that tracking errors converge exponentially to zero within balls of any arbitrarily small radii. The simulation results demonstrate the efficacy of the presented control technique, which outperforms backstepping, command-filtered backstepping, dynamic surface, synergetic control designs; deals with the "explosion of complexity" problem; and simultaneously achieves asymptotic tracking. Furthermore, even though the HTRS parameters vary, the proposed technique is capable of providing consistent control performance. As a result, the presented controller is unaffected by changes in the system's parameters.