Failed Goal Aware Hindsight Experience Replay

In multi-goal reinforcement learning for a given environment, agents learn policies to achieve multiple goals by using experiences gained from interactions with the environment. One of the key challenges in this setting is training agents using sparse binary rewards, which can be difficult due to a lack of successful experiences. To address this challenge, hindsight experience replay (HER) generates successful experiences from unsuccessful experiences. However, the process of generating successful experiences from uniformly sampled ones can be inefficient. In this paper, a novel approach called Failed goal Aware HER (FAHER) is proposed to enhance the sampling efficiency. The approach exploits the property of achieved goals in relation to failed goals that are defined as the original goals not achieved. The proposed method involves clustering episodes with different achieved goals using a cluster model and subsequently sampling experiences in the manner of HER. The cluster model is generated by applying a clustering algorithm to failed goals. The proposed method is validated by experiments with three robotic control tasks of the OpenAI gym. The results of experiments demonstrate that the proposed method is more sample efficient and achieves improved performance over baseline approaches.