Safe Curriculum Learning for Linear Systems with Parametric Unknowns in Primary Flight Control

Abstract

Safe Curriculum Learning aims at improving safety and efficiency aspects of Reinforcement Learning (RL). Curricular RL approaches divide a task into stages of increasing complexity in order to increase efficiency. This paper proposes a black box safe curriculum learning architecture applicable to systems with parametric unknowns. The agent domain solely requires knowledge of the state and action spaces’ dimensions for a given task and system. By adding system identification capabilities to existing safe curriculum learning paradigms, the proposed architecture ensures safe learning of tracking tasks without requiring initial knowledge of the system dynamics. A model estimate is generated online to complement safety filters that rely on uncertain models for their safety guarantees. This research explicitly targets linearised systems with decoupled dynamics. The paradigm is initially verified on a mass-spring-damper system, after which it is applied to a quadrotor altitude and attitude tracking task. The RL agent is able to safely learn an optimal policy that can track an independent reference on each degree of freedom.