garage.envs.mujoco.half_cheetah_vel_env module¶
Variant of the HalfCheetahEnv with different target velocity.
-
class
HalfCheetahVelEnv
(task=None)[source]¶ Bases:
garage.envs.mujoco.half_cheetah_env_meta_base.HalfCheetahEnvMetaBase
Half-cheetah environment with target velocity, as described in [1].
The code is adapted from https://github.com/cbfinn/maml_rl/blob/9c8e2ebd741cb0c7b8bf2d040c4caeeb8e06cc95/rllab/envs/mujoco/half_cheetah_env_rand.py
The half-cheetah follows the dynamics from MuJoCo [2], and receives at each time step a reward composed of a control cost and a penalty equal to the difference between its current velocity and the target velocity. The tasks are generated by sampling the target velocities from the uniform distribution on [0, 2].
- [1] Chelsea Finn, Pieter Abbeel, Sergey Levine, “Model-Agnostic
- Meta-Learning for Fast Adaptation of Deep Networks”, 2017 (https://arxiv.org/abs/1703.03400)
- [2] Emanuel Todorov, Tom Erez, Yuval Tassa, “MuJoCo: A physics engine for
- model-based control”, 2012 (https://homes.cs.washington.edu/~todorov/papers/TodorovIROS12.pdf)
Parameters: task (dict or None) – velocity (float): Target velocity, usually between 0 and 2. -
sample_tasks
(num_tasks)[source]¶ Sample a list of num_tasks tasks.
Parameters: num_tasks (int) – Number of tasks to sample. Returns: - A list of “tasks,” where each task is a
- dictionary containing a single key, “velocity”, mapping to a value between 0 and 2.
Return type: list[dict[str, float]]
-
set_task
(task)[source]¶ Reset with a task.
Parameters: task (dict[str, float]) – A task (a dictionary containing a single key, “velocity”, usually between 0 and 2).
-
step
(action)[source]¶ Take one step in the environment.
Equivalent to step in HalfCheetahEnv, but with different rewards.
Parameters: action (np.ndarray) – The action to take in the environment. Returns: - observation (np.ndarray): The observation of the environment.
- reward (float): The reward acquired at this time step.
- done (boolean): Whether the environment was completed at this
- time step. Always False for this environment.
- infos (dict):
- reward_forward (float): Reward for moving, ignoring the
- control cost.
- reward_ctrl (float): The reward for acting i.e. the
- control cost (always negative).
- task_vel (float): Target velocity.
- Usually between 0 and 2.
Return type: tuple