fix(tianji_wuji): left-hand link2 180-deg frame flip + joint2 sense flip (5 fingers)
#4
by Everloom - opened
Re-files the axis fix that was appended to PR #3 after its merge cut (merged main carries only the diffuseColor/knuckle/doubleSided sync). Base = current main; the only delta is the left-hand kinematics fix.
Measured (USD-chain FK vs MuJoCo mj_forward, palm frame, right-hand sign calibration):
- left finger{1..5} link2 body frame flipped 180 deg about local Z (0.00 mm pos error) -> identity-attached meshes render flipped ('metacarpal misplaced'), URDF-verbatim COM mirrored;
- left finger{1..5} joint2 physical sense inverted (fingertip delta 50-92 mm vs MuJoCo at sweep);
- left j3/j1/j4 and the whole right hand correct in this file revision.
Patch (zero-pose preserving re-expression):
- joint2: localRot0 *= Rz(pi); localRot1 -> Rz(pi) @ localRot1 @ Rz(pi); localPos1 -> Rz(pi) @ localPos1
- joint3: localRot0 -> Rz(pi) @ localRot0; localPos0 -> Rz(pi) @ localPos0
- limits/meshes/COM/diagonal inertia untouched (correct as-authored once the frame is unflipped).
Acceptance: all 40 hand joints swept to limit/0.8 rad - worst link4 orientation delta 0.015 deg, worst fingertip delta 0.004 mm vs MuJoCo (audit bar <= 2 mm). IsaacSim RTX A/B renders confirm the left hand now mirrors the right and matches MuJoCo.
Full writeup + repro scripts: simbench-report 05_benchmarks_infra/wuji_lefthand_axis_fix.
WORKS
Everloom changed pull request status to merged