kramp/microduck-groove

groove

In-place groove: rhythmic knee bounce with a small head sway (sim-trained, untested on hardware)

A episodic policy for the microduck (61-D observation, 14 actions, 50 Hz). Runs 10.0 s and returns itself to a standing pose.

Run it on a robot

sudo robotctl policy add groove kramp/microduck-groove
robotctl robot do groove

The observation normalizer is baked into policy.onnx; feed raw observations. manifest.json follows schema 2 of the microduck policy manifest (docs/policy-manifest.md in the daemon repo).

Training

• task_id: Mjlab-Dance-Flat-MicroDuck
• repo: pollen-robotics/microduck_rl
• branch: dance
• commit: 2f3f4ea1d
• checkpoint: 3999

What it actually does (measured in simulation)

20 s headless rollouts in CPU MuJoCo with the BAM XL330 actuator model (scripts/render_policy.py), starting from the standing pose, all command slots at zero:

• Never falls: max trunk tilt 1.6°, drift 1 cm.
• Knee bounce: hip/knee/ankle bounce in sync on both legs, at 87% of the reference amplitude, about 2.1 Hz (≈126 BPM rather than the 100 BPM target).
• Head: a small head-yaw sway at 30% of the reference amplitude. The planned head nod, head tilt and hip sway were not learned.

replay.mp4 shows it.

How it was trained

• Task Mjlab-Dance-Flat-MicroDuck (mjlab, PPO), built on the velocity recipe: domain randomization, pushes, and BAM actuators, with the twist command always zero.
• The actor gets no clock (the standard 61-D contract), so rhythm has to come from state feedback. The reward runs a phase-locked reference: it advances at the target tempo and may slip only a little, so standing still never pays.
• Reference-state initialization: 70% of episodes start mid-dance.
• 4000 iterations × 4096 envs on one L4 (HF Jobs, about 2 h 50 min).
• The training code is a local fork of pollen-robotics/microduck_rl (branch dance, not published), so the commit hash below does not exist upstream.

Caveats

• Sim-only. It has never run on a real robot. Test it held or on a soft surface first.
• The policy grooves indefinitely. When duration_s (10 s) ends, the daemon hands back to the stand policy mid-bounce rather than from a settled pose.