Safety‐Critical Optimal Control of Discrete‐Time Non‐Linear Systems via Policy Iteration‐Based Q‐Learning

ABSTRACT

This paper investigates the problem of safety-critical optimal control for discrete-time non-linear systems. A safety-critical control algorithm is developed based on Q-learning and an iterative adaptive dynamic programming, that is, policy iteration. Discrete-time control barrier functions (CBFs) are introduced into the utility function for guaranteeing safety, in which a novel definition of the safe set and its boundary with multiple discrete-time CBFs are given. Also, for discrete-time systems, by using multiple discrete-time CBFs, the safety-critical optimal control problem of multiple safety objectives is addressed. Meanwhile, safety, convergence, and stability of the developed algorithm are rigorously demonstrated. An effective method to obtain an initial safety-admissible control law is established. Also, the developed algorithm is implemented by building an actor-critic structure with neural networks. Finally, the effectiveness of the proposed algorithm is illustrated by three simulation examples.

​International Journal of Robust and Nonlinear Control, Volume 35, Issue 8, Page 2863-2881, 25 May 2025. Read More

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