Multiple Observer Adaptive Fusion for Uncertainty Estimation and Its Application to Wheel Velocity Systems

Uncertainty estimation in real-world scenarios is challenged by complexities arising from peaking phenomena and measurement noises. This article introduces a novel scheme for practical uncertainty estimation to mitigate peaking dynamics and enhance overall dynamic behavior. A fusion estimation framework for lumped uncertainties using multiple extended state observers (ESOs) is constructed, and the low-frequency adaptive parameter learning technique is employed to approximate the optimal fusion. The adaptive fusion estimation not only attenuates transient peaks in uncertainty estimation but also attains fast convergence and high accuracy under the high-gain scheduling of ESOs. Furthermore, the robustness of uncertainty estimation against measurement noises is enhanced by cascading filters in the proposed adaptive fusion framework for multiple ESOs. Extensive theoretical analyses are executed to verify practical applicability in peak and noise rejection. Finally, simulations and experiments on the wheel velocity system of a mobile robot are conducted to test the validity and feasibility.

I. Introduction

Uncertainties are prevalent in cyber-physical systems, undermining their dynamics [1], [2], [3], [4], [5], [6], [7], [8]. Uncertainty estimation can recover disturbances and unknown dynamics from measured outputs. System uncertainties are directly compensated online, enhancing control behavior and robustness. Various uncertainty estimators (UEs) address unknown system uncertainties, for example, disturbance interval observer (DIO) [9], disturbance observer (DO) [10], uncertainty and disturbance estimation (UDE) [11], extended state observer (ESO) [12], sliding mode DO (SMDO) [13], and others.