Achieving Performance and Safety in Large Scale Systems with Saturation using a Nonlinear System Level Synthesis Approach

TL;DR

This paper introduces a nonlinear control approach that combines multiple linear controllers to improve performance and safety in large-scale systems, effectively handling constraints, delays, and disturbances.

Contribution

It proposes a novel nonlinear controller structure within the System Level Synthesis framework that outperforms linear controllers in constrained LQR problems and ensures safety and performance.

Findings

Nonlinear controller outperforms linear controllers in constrained LQR tasks

Controller handles delays, sparse actuation, and local disturbances effectively

Demonstrates anti-windup property in saturated systems via simulation

Abstract

We present a novel class of nonlinear controllers that interpolates among differently behaving linear controllers as a case study for recently proposed Linear and Nonlinear System Level Synthesis framework. The structure of the nonlinear controller allows for simultaneously satisfying performance and safety objectives defined for small- and large-disturbance regimes. The proposed controller is distributed, handles delays, sparse actuation, and localizes disturbances. We show our nonlinear controller always outperforms its linear counterpart for constrained LQR problems. We further demonstrate the anti-windup property of an augmented control strategy based on the proposed controller for saturated systems via simulation.