Learning to imitate expert behavior given action demonstrations containing high-dimensional, continuous observations and unknown dynamics is a difficult problem in robotic control. Simple approaches based on behavioral cloning (BC) suffer from state distribution shift, while more complex methods that generalize to out-of-distribution states can be difficult to use, since they typically involve adversarial optimization. We propose an alternative that combines the simplicity of BC with the robustness of adversarial imitation learning. The key insight is that under the maximum entropy model of expert behavior, BC corresponds to fitting a soft Q function that maximizes the likelihood of observed actions. This perspective suggests a way to regularize BC so that it generalizes to out-of-distribution states: combine the standard maximum-likelihood objective with a penalty on the soft Bellman error of the soft Q function. We show that this penalty term gives the agent an incentive to take actions that lead it back to demonstrated states when it encounters new states. Experiments show that our method outperforms BC and GAIL on a variety of image-based and low-dimensional environments in Box2D, Atari, and MuJoCo.

提出了一种称作“软Q模仿学习”的新方法，该方法使用强化学习，但不需要学习奖励函数，而是通过鼓励智能体在遇到不在分布中的状态时返回演示状态来激励智能体进行长视野模仿。在图像和低维度任务方面表现优于基于行为克隆和生成对抗模仿学习（GAIL）的方法，可用于标准Q学习或离线策略演员-评论家算法。

SQIL: 通过稀疏奖励加强学习实现的模仿学习