Developer Walkthrough (External HOMIE Package)

This walkthrough explains the refactored mjlab-homierl layout: what still lives upstream in mjlab, what now lives in this repository, and where to change HOMIE-specific behavior without confusing package-local code with framework internals.

What you will learn here

• Package boundaries: which pieces are in upstream mjlab vs this repo.

• Code navigation: where HOMIE env cfg, assets, MDP terms, and HIMPPO live.

• Task deep-dive: how the H1 HOMIE task is assembled, including the with_hands variant and play-time overrides.

Recommended reading order

If this is your first time reading the refactored repository, follow the order below. The pages are intentionally package-specific instead of trying to mirror all upstream mjlab framework docs.

Contents

• Architecture Overview: External Package on Top of mjlab
  • The one sentence that matters most
  • From task id to the training loop (end-to-end)
  • A readable control-flow sketch
  • Where to start reading code
• Code Map: Where Should You Change Things?
  • Key directories
  • What is upstream now?
• Example 3: Homie — Mixed Motion and Disturbances (Unitree H1)
  • Task registration
  • Task skeleton: make_homie_env_cfg (base cfg)
  • Env grouping: train three “subtasks” in one vectorized env
  • H1 override: unitree_h1_homie_env_cfg
  • Core feature: UpperBodyPoseAction (policy-free, 0-dim action)
  • Curriculum: gradually increase disturbance strength
  • Rewards & terminations: balancing mixed objectives
  • H1 override and H1 constants
  • with_hands: gripper variant (policy-free)
  • Play-time runner behavior
  • Why Homie is a good reference