Finite time parameter estimation-based adaptive predefined performance control for servo mechanisms

This paper proposes an adaptive funnel control scheme for two-inertia servo systems with unknown parameters (e.g., inertia and stiffness coefficient). To improve the transient and steady-state performance, a modified funnel variable, which relaxes the limitation of the original funnel control, is developed by using the tracking error to replace the scaling factor. Then, an error transformation with the new funnel variable is introduced and used in the controller design. An auxiliary filter operation is designed to derive the information of parameter estimation error, which is used as a new leakage term in the parameter update law. Then a sliding mode technique is introduced in the adaption law to achieve finite-time convergence. Appropriate comparison to the gradient descent method is provided concerning with the estimation convergence. Simulation and experimental results are used to illustrate the effectiveness of the devised control scheme.