State-wise Safe Reinforcement Learning With Pixel Observations

Reinforcement Learning(RL) in the context of safe exploration has long grappled with the challenges of the delicate balance between maximizing rewards and minimizing safety violations, the complexities arising from contact-rich or non-smooth environments, and high-dimensional pixel observations. Furthermore, incorporating state-wise safety constraints in the exploration and learning process, where the agent is prohibited from accessing unsafe regions without prior knowledge, adds an additional layer of complexity. In this paper, we propose a novel pixel-observation safe RL algorithm that efficiently encodes state-wise safety constraints with unknown hazard regions through the introduction of a latent barrier function learning mechanism. As a joint learning framework, our approach first involves constructing a latent dynamics model with low-dimensional latent spaces derived from pixel observations. Subsequently, we build and learn a latent barrier function on top of the latent dynamics and conduct policy optimization simultaneously, thereby improving both safety and the total expected return. Experimental evaluations on the safety-gym benchmark suite demonstrate that our proposed method significantly reduces safety violations throughout the training process and demonstrates faster safety convergence compared to existing methods while achieving competitive results in reward return.