HP3O: Hybrid-Policy Proximal Policy Optimization with Best Trajectory

ICLR 2025 Conference Submission11700 Authors

Keywords: Reinforcement learning, proximal policy optimization, hybrid policy, trajectory replay buffer, variance reduction

TL;DR: Proximal Policy Optimization (HP3O) leverages a trajectory replay buffer to enhance the efficiency of utilizing trajectories generated by recent policies.

Abstract: Proximal policy optimization (PPO) is one of the most popular state-of-the-art on-policy algorithms that has become a standard baseline in modern reinforcement learning with applications in numerous fields. Though it delivers stable performance with theoretical policy improvement guarantees, high variance and high sample complexity still remain critical challenges in on-policy algorithms. To alleviate these issues, we propose Hybrid-Policy Proximal Policy Optimization (HP3O), which utilizes a trajectory replay buffer to make efficient use of trajectories generated by recent policies. Particularly, the buffer applies the "first in, first out" (FIFO) strategy so as to keep only the recent trajectories to attenuate the data distribution drift. A batch consisting of the trajectory with the best return and other randomly sampled ones from the buffer is used for updating the policy networks. The strategy helps the agent to improve its capability on top of the most recent best performance and in turn reduce variance empirically. We theoretically construct the policy improvement guarantees for the proposed algorithm. HP3O is validated and compared against several baseline algorithms using multiple continuous control environments. Our code is available here.

Primary Area: reinforcement learning

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Submission Number: 11700