Emergence of Locomotion Behaviours in Rich Environments
  The reinforcement learning paradigm allows, in principle, for complex
behaviours to be learned directly from simple reward signals. In practice,
however, it is common to carefully hand-design the reward function to encourage
a particular solution, or to derive it from demonstration data. In this paper
explore how a rich environment can help to promote the learning of complex
behavior. Specifically, we train agents in diverse environmental contexts, and
find that this encourages the emergence of robust behaviours that perform well
across a suite of tasks. We demonstrate this principle for locomotion --
behaviours that are known for their sensitivity to the choice of reward. We
train several simulated bodies on a diverse set of challenging terrains and
obstacles, using a simple reward function based on forward progress. Using a
novel scalable variant of policy gradient reinforcement learning, our agents
learn to run, jump, crouch and turn as required by the environment without
explicit reward-based guidance. A visual depiction of highlights of the learned
behavior can be viewed following https://youtu.be/hx_bgoTF7bs .
