The same hybrid learning framework is used for both box climbing and box
moving. Its key ideas are:
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The actor does not observe the target reference motion. We find that this
design can achieve high-quality motion tracking across a wide range of
tasks; see the HIL paper for more details.
The actor only observes the robot state and sparse task conditions or goals,
while the reference motion is used to define the goals and tracking rewards.
Because the policy is conditioned on task goals rather than a reference
motion, the learned behavior can easily transfer to new task conditions.
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Training combines two types of environments.
- In reference-tracking environments, goals and task conditions are extracted from the
reference motion and the policy is trained with tracking rewards.
- In general RL environments, goals and task conditions are randomized
and the policy is trained with sparse goal-reaching rewards.
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One policy is jointly optimized on two types of environments. The actor always uses the
same observation interface across track and general RL envs, while the critic receives task-specific privileged information. This allows behavior learned from a small reference set to generalize to a wide range of task conditions and goals.