Design and Experimental Verification of UDE-based Robust Control for Lagrangian Systems without Velocity Measurements

Abstract

This paper presents an UDE (uncertainty and disturbance estimator) based control approach to position trajectory tracking of a vehicle system without velocity measurements. The vehicle dynamics is described by a disturbed Lagrangian equation. The control strategy is developed by applying passivity techniques to inject damping into the system, and UDE techniques to achieve robustness improvement with respect to input disturbances. A class of new linear filters are identified, by which neither velocity measurements or their estimates are required for UDEs. A novel parameter mapping is proposed to obtain a simple relationship between the design parameter and the ultimate bounds of error trajectories. Both simulation and experimental results for the angular position trajectory tracking of a 3-DOF helicopter demonstrate the effectiveness of the proposed control strategy.