Constrained model-free reinforcement learning for process optimization

Abstract

Reinforcement learning (RL) is a control approach that can handle nonlinear stochastic optimal control problems. However, despite the promise exhibited, RL has yet to see marked translation to industrial practice primarily due to its inability to satisfy state constraints. In this work we aim to address this challenge. We propose an “oracle”-assisted constrained Q-learning algorithm that guarantees the satisfaction of joint chance constraints with a high probability, which is crucial for safety critical tasks. To achieve this, constraint tightening (backoffs) are introduced and adjusted using Broyden’s method, hence making the backoffs self-tuned. This results in a methodology that can be imbued into RL algorithms to ensure constraint satisfaction. We analyze the performance of the proposed approach and compare against nonlinear model predictive control (NMPC). The favorable performance of this algorithm signifies a step towards the incorporation of RL into real world optimization and control of engineering systems, where constraints are essential.

Publication
Computers & Chemical Engineering
Dr. Ehecatl Antonio del Rio Chanona
Dr. Ehecatl Antonio del Rio Chanona
Principal Investigator of OptiML

Antonio del Rio Chanona is the head of the Optimisation and Machine Learning for Process Systems Engineering group based in thee Department of Chemical Engineering, as well as the Centre for Process Systems Engineering at Imperial College London. His work is at the forefront of integrating advanced computer algorithms from optimization, machine learning, and reinforcement learning into engineering systems, with a particular focus on bioprocess control, optimization, and scale-up. Dr. del Rio Chanona earned his PhD from the Department of Chemical Engineering and Biotechnology at the University of Cambridge, where his outstanding research earned him the prestigious Danckwerts-Pergamon award for the best PhD dissertation of 2017. He completed his undergraduate studies at the National Autonomous University of Mexico (UNAM), which laid the foundation for his expertise in engineering.