Gantry
Gantry · dataset evaluation · 16 September 2026

Lightwheel-Tasks-Double-Piper records six joints an arm and commands five

LightwheelAI/Lightwheel-Tasks-Double-Piper, measured from the public release on 16 September 2026.

a joint the release records and cannot command

What is in the release

Every row is read out of the release. Nothing here is estimated and nothing is rounded up.

episodes declared in the release6,500
episodes read at frame level1,687
dimensions in observation.state16
dimensions in action12
arm joints named in observation.statejoint1 to joint6, both arms
arm joints named in actionjoint1, joint2, joint3, joint5, joint6
joint present in state and absent from actionjoint4, on both arms
episodes in which joint4_l moves1,242 of 1,687, 73.6%
furthest joint4_l travels in one episode0.8715 radians, 49.9 degrees
episodes in which joint4_r moves620 of 1,687, 36.8%
furthest joint4_r travels in one episode0.1955 radians
median travel of the uncommandable joints0.0105 radians
median travel of the joints that are commanded0.5137 radians

This is not a claim that the arm is still. Every other joint of the same naming series is commanded, so the gap is in the action space rather than in the behaviour. The check was also run against the so101 releases in the same account, where all six joints are commandable and there is nothing to report.

Why this matters

A policy trained on this action space cannot command joint4, while the observations it is trained against show joint4 moving in most episodes. Behaviour cloning then fits a five joint command to a six joint motion, and the residual has nowhere to go except into the other five joints.

How to check this without taking our word for it

Read meta/info.json and compare the names list under action with the names list under observation.state. The gap is visible without downloading a single parquet file.

What a full grading adds

This page is what the release tells you on its own. A full grading removes the part that scores worst, retrains on what is left, and reports whether the smaller corpus scores higher, with rollout counts and intervals. The one result measured on physical hardware is Stera-10M, two arms on a four arm SO-ARM101 bench, 21.9% against 36.9% task success across 1,270 rollouts. The Stera-10M report.