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Motrixlab/docs/source/en/user_guide/tutorial/physics_environment.md
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Physics Environment Configuration

Physics environment configuration defines simulation parameters and model file settings in reinforcement learning training. MotrixLab uses MotrixSim as the physics simulation backend.

Supported File Formats

  • MJCF (MuJoCo XML format) - Provides rich physics features and simulation configuration

Model File Configuration

You need to specify model file paths in environment configuration classes:


@registry.envcfg("my-task")
@dataclass
class MyTaskEnvCfg(EnvCfg):
    # Model file path (required)
    model_file: str = "my_model.xml"

    # Simulation time parameters
    sim_dt: float = 0.002      # Simulation time step
    ctrl_dt: float = 0.02      # Control update frequency

    # Episode parameters
    max_episode_seconds: float = 20.0
    reset_noise_scale: float = 0.01
motrix_envs/my_task/
├── __init__.py          # Module initialization
├── cfg.py               # Environment configuration
├── my_model.xml         # Physics model file
└── my_env.py            # Environment implementation

For complex models with many referenced files, it's recommended to use folder management.

Common Configuration Issues

File Path Issues

  • When using relative paths, ensure paths are relative to the configuration file location
  • Avoid using hardcoded absolute paths
  • Check file permissions and accessibility
  • Ensure all referenced sub-files exist

Time Step Settings

  • ctrl_dt should be an integer multiple of sim_dt
  • sim_dt that is too small will affect simulation performance
  • ctrl_dt that is too large will affect control precision
  • Recommend sim_dt between 0.001-0.02 seconds

Simulation Stability

  • Avoid excessively large time steps
  • Set contact parameters reasonably to avoid penetration
  • Mass and inertia distribution should be reasonable
  • Joint limits should match actual conditions

Through proper physics environment configuration, you can create accurate and efficient simulation environments for reinforcement learning training.