Enhanced Scene Specificity with Sparse Dynamic Value Estimation
This work provides an incremental improvement for reinforcement learning agents operating in multi-scene environments by reducing sample variance and improving performance.
This paper addresses the issue of increased sample variance in multi-scene reinforcement learning, which leads to suboptimal performance. The authors propose a method that reduces the error between true scene-specific value functions and predicted dynamic estimates by enforcing sparse cluster assignments. This approach significantly improves final reward scores in OpenAI ProcGen environments and enhances navigation efficiency.
Multi-scene reinforcement learning involves training the RL agent across multiple scenes / levels from the same task, and has become essential for many generalization applications. However, the inclusion of multiple scenes leads to an increase in sample variance for policy gradient computations, often resulting in suboptimal performance with the direct application of traditional methods (e.g. PPO, A3C). One strategy for variance reduction is to consider each scene as a distinct Markov decision process (MDP) and learn a joint value function dependent on both state (s) and MDP (M). However, this is non-trivial as the agent is usually unaware of the underlying level at train / test times in multi-scene RL. Recently, Singh et al. [1] tried to address this by proposing a dynamic value estimation approach that models the true joint value function distribution as a Gaussian mixture model (GMM). In this paper, we argue that the error between the true scene-specific value function and the predicted dynamic estimate can be further reduced by progressively enforcing sparse cluster assignments once the agent has explored most of the state space. The resulting agents not only show significant improvements in the final reward score across a range of OpenAI ProcGen environments, but also exhibit increased navigation efficiency while completing a game level.