Adaptive Robust Control for Uncertain Systems with Ellipsoid-Set Learning

TL;DR

This paper introduces an adaptive robust control method for linear uncertain systems using ellipsoid-set learning to handle non-Gaussian uncertainties, improving control performance by reducing conservativeness.

Contribution

It proposes a novel ellipsoid-set learning approach combined with a candidate-conditional control framework to effectively manage uncertainties and parametric variations.

Findings

Effective control in numerical simulations for LQR and tracking.

Reduced conservativeness compared to traditional robust control.

Decoupled learning and control processes enhance attainability.

Abstract

Despite the celebrated success of stochastic control approaches for uncertain systems, such approaches are limited in the ability to handle non-Gaussian uncertainties. This work presents an adaptive robust control for linear uncertain systems, whose process noise, observation noise, and system states are depicted by ellipsoid sets rather than Gaussian distributions. We design an ellipsoid-set learning method to estimate the boundaries of state sets, and incorporate the learned sets into the control law derivation to reduce conservativeness in robust control. Further, we consider the parametric uncertainties in state-space matrices. Particularly, we assign finite candidates for the uncertain parameters, and construct a bank of candidate-conditional robust control problems for each candidate. We derive the final control law by aggregating the candidate-conditional control laws. In this way, we separate the control scheme into parallel robust controls, decoupling the learning and control, which otherwise renders the control unattainable. We demonstrate the effectiveness of the proposed control in numerical simulations in the cases of linear quadratic regulation and tracking control.