[moveit_resources] Panda joint4 soft upper limit still allows planning beyond the datasheet spec (related to #116)

[147258369ymc]

Description

The Panda URDF/SRDF used by MoveIt CI declares panda_joint4 with an upper
soft limit of roughly +0.0175 rad (+1°), whereas the Franka datasheet
specifies the joint4 upper limit at about -0.0698 rad (-4°). Issue #116
documents this ~5° discrepancy.

This reproducer shows the consequence at the planning layer: the motion
planner commands panda_joint4 to a position that is valid under the (wrong)
URDF limit but outside the datasheet limit [-3.0718, -0.0698] rad.

To Reproduce

docker exec -it moveit_modify bash
source /ros_entrypoint.sh && cd /robofuzz/src
python3 replay_moveit_bug.py \
  --from-log /robofuzz/src/logs/20260618-150444 \
  --case position_joint4 --mode offline

Goal sequence (6 goals, all action-status SUCCESS/ABORT aligned [4,6,4,4,4,4]):

goal	x	y	z
1	0.2968	0.2449	0.4064
2	0.2207	0.0201	0.4907
3	0.2755	-0.2108	0.5855
4	0.4444	-0.3774	0.5840
5	0.6000	-0.4290	0.4879
6	0.6000	-0.3498	0.4054

Expected Behavior

With limits matching the datasheet (joint4 upper = -0.0698 rad), the planner
should never command joint4 above -0.0698 rad.

Actual Behavior

planner desired position for panda_joint4: -0.0423 outside [-3.0718, -0.0698] rad

-0.0423 rad (-2.42°) is above the datasheet upper limit -0.0698 rad
(-4.0°) by ~1.6°, but within the URDF's wrong +0.0175 rad limit — so MoveIt
considers it valid and plans/executes it. The subsequent measured-position
samples confirm the joint dwells in the out-of-spec region for the whole motion
(781 sample points in [-3.94°, -2.42°], all above -4.0°).

Analysis

• Root cause: data, not code — the Panda position limits in moveit_resources
  do not match the Franka datasheet (exactly Update "robot_model_and_robot_state_tutorial" to ROS2 #116).
• This reproducer adds: the wrong limit is not merely declared, it is
  actively reached through normal planning, so the spec violation is
  observable end-to-end, not just static config.

Root cause location: moveit_resources Panda description
(panda_arm.urdf.xacro / joint_limits), per #116. Fixed by PR #118 if merged.

Relation to Existing Issues

Duplicate-class of #116.
Filed as a confirming reproducer for the ROS2 Foxy / moveit_core 2.2.3 package
set. Close as duplicate if already resolved on the branch you ship.

Additional Info

• ROS2 Foxy, moveit_core 2.2.3, moveit_resources Panda config.
• RoboFuzz's own README notes it suppresses this exact violation via an oracle
  MARGIN so it doesn't drown out other bugs — consistent with this being the
  known, always-triggerable Update "robot_model_and_robot_state_tutorial" to ROS2 #116.

moveit.issue3.joint4.mp4