docs/rl_implementation_plan.md

RL implementation plan

Train a hand/wrist policy on frozen SONIC, using CoordEx’s 12-D hand latent as the finger action, relative poses (object and palm frames) instead of world-frame clip tracking, and smoothed commands instead of replaying HaWoR/retarget q as the target.

This is not a plan to train SONIC, not a plan to train CoordEx’s body VAE, and not a plan to DeepMimic the DexYCB trajectory.

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0. Decision (locked)

Choice	Why
Body = frozen SONIC v1.1 ONNX	Already tracks standing / walk references. CoordEx body prior is a different teacher; do not mix two body controllers.
Fingers = frozen CoordEx hand VAE (prior + decoder)	12-D latent of Wuji finger skills. Query prior_net → μ, add PPO residual Δz, decode. The posterior encoder is distillation-only; we reuse its latent space, not E(z | s^g, s^p) at RL time.
Wrist = SONIC teleop target in the pelvis frame, then optionally object-relative residuals	World-frame HaWoR wrist is unreachable and noisy.
Demo from video = object-frame grasp geometry + smoothed finger curl	Never use camera/world q or the raw retarget trajectory as s^g.
Task reward first, clip shaping second	Lift / contact on the reconstructed can. Weak relative-demo terms only after contact exists.

Encoder vs prior (do not mix these up in code):

CoordEx distillation:  encoder(obs_with_goal) → z     # unused at RL time
CoordEx / our RL:      μ = prior(hand_proprio)         # 12-D
                       z̃ = μ + Δz                      # Δz from PPO
                       a_fingers = decoder(proprio, z̃) # 20 Wuji joints

Checkpoint: third-party/coordex/ckpts/hand_prior/kinematic_wrist_16k.pt
Variant: wuji_floating_kinematic_wrist (66-D proprio, 12-D latent, 20 finger actions).
Do not load body_prior/walkgrab_10k.pt into the SONIC env.

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1. What is already implemented

Reconstruction / retarget (data, not RL)

Piece	Status
RGB → SAM3 / SAM3D / HaWoR / object 6-DoF	Done (reconstruction/)
MANO → Wuji IK (g1_wuji_retarget.npz)	Done (retarget/). Wrist free-flyer is HaWoR camera frame.
Isaac pack isaaclab_replay.npz + textured object.urdf	Done
Relocate object into SONIC wrist band; flatten Y-up rest pose	Done (sonic/clip_motion.py, object_rest.py)

Frozen whole-body

Piece	Status
SONIC v1.1 ONNX, Isaac Lab joint order, batched graphs	Done (v2d_sim/sonic/)
Standing teleop: 3-point VR, right wrist commanded	Done (BatchedSonicController)
Walk reference from MotionBricks planner + g1 mode track	Done (planner_ref.py, g1_sonic_walkgrab/) — play only, not in the PPO env
Wrist tracking probe (bias ~8 cm, usable band documented)	Done

Gym tasks

Gym id	What it is	Trainable for this goal?
V2D-G1-TableObject-v0	G1 minimal USD, cuboid table/box, joint PD stub	No. rl/train.sh still defaults here.
V2D-G1-SonicManip-v0	Wuji G1, reconstructed can, frozen SONIC, 4-D wrist xyz + 1-D grip	Scaffold yes. Action/obs/reward not the CoordEx-latent design.
V2D-G1-SonicWalkGrab-v0	Walk then wrist; planner clip	Locomotion carrier. No PPO, no hand VAE.
V2D-CoorDex-WalkGrab-Play-v0	Full CoordEx residual actor + both VAEs + WalkGrab layout	Literature baseline play. ~3 mm lift on our can. Not our trainer.

V2D-G1-SonicManip-v0 in detail (the env to extend)

Implemented

• Scene: standing pelvis z=0.78, object at ~(0.36, −0.20) on a shallow table, coffee-can URDF, upright rest quat.
• Action SonicWristAction: 4-D in [−1,1] → pelvis-frame wrist box + uniform finger flexion. SONIC 50 Hz inside the term; fingers not through a VAE (one scalar × joint limits).
• Obs (~20-D): projected gravity, achieved wrist in pelvis, object in pelvis, object−wrist, object lin vel (pelvis), grip, last action.
• Reward: tanh reach, lift-from-rest gated on proximity, alive, fall, torso, action-rate.
• Reset: object xy/yaw jitter about world vertical (correct composition for Y-up mesh).
• Rates: physics 200 Hz, SONIC 50 Hz, policy 25 Hz (dt=0.005, decimation=8).
• PPO cfg: small MLP 256–128, 4-D Gaussian, 3000 iters (G1SonicManipPpoRunnerCfg).
• rl/scripts/train.py: RSL-RL OnPolicyRunner via RslRlPpoTrainer — algorithm wrapper exists, pointed at whatever --task you pass.

Not implemented (this is the work)

• CoordEx StudentTeacherVAE load / prior_mean / decode on the SONIC robot.
• 12-D hand residual in the action (still 1-D grip).
• Object-frame or palm-frame observations (everything is pelvis- or world-z).
• Demo buffer of relative grasp (palm–object, fingertips–object, filtered finger q).
• Smoothing beyond a small action-rate penalty (no EMA on wrist or Δz; process_actions writes the command every policy step).
• Fingertip contact forces (CoordEx WalkGrab needs them; our env does not expose them).
• Wrist orientation as an action (held at standing VR quat).
• Clip-conditioned phase / RSI from retarget.
• rl/train.py default task is still V2D-G1-TableObject-v0.
• Play script for SonicManip + checkpoint (play.py is table-object zeros/random).

CoordEx code we can import (do not reimplement)

Already in-tree, used by the WalkGrab play port:

• coordex.distillation.vae.StudentTeacherVAE
• coordex.tasks.locomanip.mdp.actions._load_student_prior / _PriorPolicy.infer_with_delta
• right_hand_proprio (66-D: palm vel in palm frame, 20 q, 20 dq, 20 last a)
• Checkpoint loader that strips actor. for teacher and keeps prior+decoder for rollout

Isaac Lab 6 ProxyArray shims live in tasks/coordex_v2d/proxy_compat.py. Reuse that pattern if the VAE path touches asset.data.

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2. What we will not do

• Train or finetune SONIC; train CoordEx body prior; joint-space PPO on 29/49/69 DoF.
• Use world-frame or camera-frame retarget q / wrist xyz as a tracking target (s^g).
• Replay DexYCB layout (object at ~1.1 m).
• Primary loss = per-frame MANO/Wuji trajectory MSE (noisy, wrong workspace).
• Copy CoordEx WalkGrab rewards (walk to x=1.5, bottle cylinder, fingertip-filter that is dead on our mesh).
• Run the VAE encoder in the RL loop (it needs a reference goal the video does not provide cleanly).

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3. Target MDP (what to implement)

One Gym id, extend g1_sonic_manip (keep the current 4-D env as a smoke/regression if needed via a cfg flag or G1SonicManipLiftCfg).

3.1 Action (smooth, latent, not clip q)

15-D raw policy output, all in [−1, 1], then smoothed:

Dim	Meaning	After process
3	Wrist residual in the object frame (or pelvis, see note)	EMA → add to a default hover pose expressed in that frame → convert to SONIC pelvis-frame target, clamp to probe box
12	Hand latent residual Δz	z̃ = μ + scale * tanh(Δz); μ = prior(right_hand_proprio)

Smoothing (required)

• Exponential moving average on both wrist residual and Δz (α ≈ 0.15–0.35 at 25 Hz), reset EMA on env reset.
• Keep / strengthen action_rate on the pre-EMA or post-EMA command (penalise both jitter and lag if needed).
• Optional: policy outputs deltas of the residual (a_t integrates), which is smoother than absolute 15-D every step.

Note on wrist frame: prefer object-relative. Default hover = a fixed offset in the object frame (e.g. palm above can, from median pre-grasp of the relocated, object-frame demo — a constant, not a time series). PPO only learns a small 3-D nudge. Convert T_object * hover * residual into pelvis xyz for SONIC. That is “relative pose,” not “follow hand_pos_w[t].”

Fingers never see a 20-D q_demo[t]. They only see μ(proprio) + Δz.

3.2 Observation (relative)

Keep SONIC-bias loop closure (achieved wrist). Add object-centric terms. Drop world xyz.

Term	Dim	Status
projected_gravity	3	Have
achieved wrist in pelvis	3	Have (needed for SONIC bias)
object in pelvis	3	Have
object → wrist in pelvis	3	Have
object lin vel in pelvis	3	Have
last action	15	Have pattern, dim change
object pose in palm (pos + 6D rot)	9	Missing (CoordEx cube_pose_in_hand)
μ_hand (prior mean)	12	Missing
last Δz	12	Missing
grip / mean finger flexion	1	Have as 1-D command; keep decoded mean
fingertip–object distances (5)	5	Missing (positions, not PhysX filter)

Skip force_matrix_w until a smoke shows contacts; CoordEx’s filtered wrench is unreliable on this URDF.

Do not add e_abs / e_rel vs isaaclab_replay world object path as the main obs. If a demo term is added later, it must be object-frame (palm pose relative to can at contact time), not (x_t − x_0) in world.

3.3 Reward (task first)

1. Reach: palm / fingertips to object (object frame or Euclidean), same spirit as current tanh.
2. Contact proxy: min fingertip–object distance, or n tips below a threshold.
3. Lift from rest height, gated on proximity/contact (already implemented — keep).
4. Smoothness: action-rate on 15-D; optional jerk on object.
5. Fall / table-knock / object-off-table (have fall + object_fell).
6. Optional weak relative-demo: exp(−‖q_fingers − q_rel_demo‖) only while palm is near the object, with q_rel_demo a single smoothed grasp shape or a 5-frame blend, not the full clip.

Success metric for reports: lift > 5 cm while grasped, fall rate, action smoothness (‖a_t − a_{t−1}‖), not ‖object − clip_world‖.

3.4 Demo preprocessing (offline, once per clip)

New small script (not in the RL loop):

1. Load g1_wuji_retarget.npz + object poses from isaaclab_replay.npz.
2. Drop frames with high tip_err or object-track jumps.
3. Low-pass finger q and palm pose.
4. Express palm and fingertips in the object frame; resample to 50 Hz.
5. Pick a contact window; store:
   • hover_offset_obj (median pre-grasp palm in object frame)
   • q_grasp (median closed shape, 20-D)
   • optional short relative trajectory for RSI only (start some episodes with palm near hover)

Write reconstruction/runs/<clip>/obj_tracking_out/grasp_relative.npz. The MDP reads this constant/window, never the raw camera trajectory.

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4. Phased work

Do not start PPO until Phase B’s scripted latent+hover smoke moves the can more than the current 1-D grip smoke (~0 cm lift, ~6 cm hand gap).

Phase A — Wire frozen hand VAE into SonicManip (no PPO)

Work

• New action term SonicWristHandLatentAction (or flag on the existing term): load kinematic_wrist_16k.pt with the same helper CoordEx uses; build 66-D right_hand_proprio on Wuji joint names; μ = prior(obs); decode μ with Δz=0; PD the 20 fingers; SONIC still owns 29 body joints + wrist target.
• Hold wrist at current hover (center of probe box) or at hover_offset_obj converted to pelvis.
• EMA on decoded finger targets (CoordEx already has hand_action_moving_average — copy the idea).
• proxy_compat if joint_pos is a ProxyArray.
• Obs: expose μ for debugging.

Gate. Env steps; robot stands; fingers take a stable pose (not NaN, not limit bang); μ finite and slowly varying as the arm moves. Video: runs/sonic_manip/vae_zero_delta.mp4.

Phase B — Relative hover + scripted close (no PPO)

Work

• Offline grasp_relative.npz for coffee can (and later sugar box).
• Wrist target = object-frame hover → pelvis, clamped to probe box.
• Script: approach (Δz=0), then interpolate Δz toward a constant that decodes near q_grasp (solve once: least-squares Δz so decoder(μ, μ+Δz) ≈ q_grasp at a recorded proprio, or just ramp a few latent axes). Not q[t] from the clip.
• Log: palm–object, min tip–object, object Δz vs rest, ‖a_t − a_{t−1}‖.

Gate. Object lifts or at least displaces vs no-op. If still no contact: fix hover (bias from probe), table friction, thumb CMC limits (already 0.05 on WalkGrab). Do not train.

Phase C — Relative obs + 15-D action + smoothness

Work

• Palm-frame object pose; fingertip distances; μ; last Δz.
• Policy action 3+12 with EMA; action-rate on 15-D.
• Rewards as §3.3; no world-clip tracking terms.
• Episode ~6–8 s; object reset with small xy jitter, modest yaw.
• Point rl/train.py default --task V2D-G1-SonicManip-v0 (or V2D-G1-SonicHandLatent-v0 if split). play.py loads RSL-RL checkpoint, records mp4, prints lift / smoothness.

Gate. train.sh --headless --num_envs 32 --max_iterations 2 with SONIC_ORT_CUDA=1. Random policy does not fall immediately. Expert-script return (Phase B) ≫ zero-action return.

Phase D — PPO

Work

• Actor/critic: not CoordEx’s 28-D coord residual (that expects body μ + cube forces). New MLP: obs → 15-D, similar size to G1SonicManipPpoRunnerCfg or slightly larger (512–256) because of 12-D Δz.
• Freeze VAE and SONIC (requires_grad=False; ONNX already frozen).
• Start num_envs=32, then 64–256 if H100 memory allows (SONIC + Wuji + VAE).
• Metrics: lift cm, contact fraction, fall rate, mean ‖Δa‖, mean ‖Δz‖ (residuals should stay small if the prior is useful).

Gate. Beats Phase B scripted lift, or matches it with closed-loop correction of SONIC wrist bias. If Δz saturates at ±1 and fingers look unlike a grasp, the prior is OOD for this can → Phase E.

Phase E — Only if D stalls

In order:

1. Probe-bias on wrist hover (signed 8 cm) so 3-D residual stays small.
2. Distill a new hand prior from the floating-hand replay of object-frame smoothed clip (wrist written in, fingers track filtered q). Then PPO residual on that μ. This is the only time we train something CoordEx-encoder-like, and the goal is still relative.
3. Wrist orientation (6-D) if palm-down vs standing yaw cannot grasp.
4. After standing grasp works: attach walk (SonicWalkWristAction handover) so locomotion stays frozen planner+SONIC and the same 15-D policy runs in reach phase.

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5. File-level sketch

Path	Change
simulation/scripts/export_grasp_relative.py	New. Offline object-frame demo.
v2d_sim/tasks/g1_sonic_manip/mdp/hand_prior.py	New. Load VAE, proprio, infer_with_delta.
v2d_sim/tasks/g1_sonic_manip/mdp/actions.py	Wrist + 12-D latent, EMA, object-frame hover.
.../mdp/observations.py	Palm-frame object, μ, tip distances.
.../mdp/rewards.py	Keep lift gate; add tips; smoothness; no world clip MSE.
.../g1_sonic_manip_env_cfg.py	New action/obs; optional split cfg class.
.../agents/rsl_rl_ppo_cfg.py	Action dim 15; hidden sizes.
rl/scripts/train.py, play.py, train.sh	Default SonicManip; play checkpoint + metrics.
docs/rl_implementation_plan.md	This file.

Do not modify coordex sources; import and shim.

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6. Order of work

A  load kinematic_wrist_16k.pt in SonicManip, Δz=0, stand
     └─ gate: stable fingers, finite μ
B  object-frame hover + scripted latent close; grasp_relative.npz
     └─ gate: object moves vs no-op
C  15-D smooth action, relative obs, rewards; trainer default task
     └─ gate: 2 PPO iters
D  train; compare lift / smoothness to B
E  new relative-only hand distill, or walk handover, only if D saturates

Start A on clip 20200709_141754 (coffee can already in the env). Parallel: CoordEx WalkGrab play stays a literature number, not this training path.