A Unified Framework for Online Data-Driven Predictive Control with Robust Safety Guarantees

TL;DR

This paper introduces a unified online data-driven predictive control framework that eliminates the need for an accurate model and reduces computational costs while ensuring safety for nonlinear systems.

Contribution

It develops a novel spatial-temporal filter-based learning scheme and a robust control barrier function for safe, efficient, data-driven nonlinear predictive control.

Findings

Achieves comparable control performance with significantly lower computational cost.

Successfully applied to cart-inverted pendulum and automotive powertrain control.

Demonstrates robustness against model uncertainties through online policy correction.

Abstract

Despite great successes, model predictive control (MPC) relies on an accurate dynamical model and requires high onboard computational power, impeding its wider adoption in engineering systems, especially for nonlinear real-time systems with limited computation power. These shortcomings of MPC motivate this work to make such a control framework more practically viable for real-world applications. Specifically, to remove the required accurate dynamical model and reduce the computational cost for nonlinear MPC (NMPC), this paper develops a unified online data-driven predictive control pipeline to efficiently control a system with guaranteed safety without incurring large computational complexity. The new aspect of this idea is learning not only the real system but also the control policy, which results in a reasonable computational cost for the data-driven predictive controllers. More specifically, we first develop a spatial temporal filter (STF)-based concurrent learning scheme to systematically identify system dynamics for general nonlinear systems. We then develop a robust control barrier function (RCBF) for safety guarantees in the presence of model uncertainties and learn the RCBF-based NMPC policy. Furthermore, to mitigate the performance degradation due to the existing model uncertainties, we propose an online policy correction scheme through perturbation analysis and design of an ancillary feedback controller. Finally, extensive simulations on two applications, cart-inverted pendulum and automotive powertrain control, are performed to demonstrate the efficacy of the proposed framework, which shows comparable performance with much lower computational cost in comparison with several benchmark algorithms.