HalfCheetah
superdex_gym/HalfCheetah-v0 · superdex.lab.gym.envs.benchmarks.halfcheetah_env.HalfCheetahEnv
Description
HalfCheetah provides planar (2-D) running. The reward favors forward velocity and penalizes control effort.
Action Space
The action is a (6,) Box. The element control is bounded [-1.0, 1.0] and
applied as external forces on DOFs 3-8 with per-joint force scales
[120, 90, 60, 120, 60, 30].
Observation Space
The observation is a (17,) Box with the default configuration, flattened in
alphabetical key order:
| Key | Shape | Meaning |
|---|---|---|
pose | 8 | num_dofs (9) - 1 for the excluded x-coordinate |
vel | 9 | One per DOF |
There is no contact observation. Turning off
exclude_current_position_from_observation adds 1.
Rewards
The scalar reward is the sum of two terms:
| Term | Value |
|---|---|
forward | x_velocity * forward_reward_weight |
ctrl | -control_cost_weight * dot(control, control) |
Starting State
The scene is restored to its captured initial state, then uniform reset noise scaled
by reset_noise_scale (default 0.1) is added to the pose and velocity.
Episode End
HalfCheetah never terminates; it does not override the stop criteria, so terminated
is never True. It only truncates at steps_per_episode.
Arguments
In addition to the shared MochiEnvCfg fields (see the Authoring guide's base
configuration section), HalfCheetahEnvCfg accepts:
| Field | Default | Meaning |
|---|---|---|
control_frequency | 20 | Control frequency [Hz] |
simulation_frequency | 100 | Simulation frequency [Hz]; 5 substeps per control step |
steps_per_episode | 1000 | Truncation limit |
reset_noise_scale | 0.1 | Scale of the uniform reset noise |
forward_reward_weight | 1 | Weight of the forward-progress term |
control_cost_weight | 0.1 | Weight of the control-cost penalty |
exclude_current_position_from_observation | True | Omit the x-coordinate |
use_gravity | True | Apply gravity |
use_rest_springs | True | Apply rest springs to the joints |
Scene identity
uid_fields = (use_gravity, use_rest_springs).
Variants
HalfCheetahFullObservation
superdex_gym/HalfCheetahFullObservation-v0
| Field | Value |
|---|---|
exclude_current_position_from_observation | False |