Bug report: Franka Panda ROS MoveIt sample fails due to outdated franka_description urdf

In Isaac Sim, in the ROS MoveIt sample with the Franka panda arm: MoveIt Motion Planning Framework — Omniverse Robotics documentation

Motion planning fails with the error:
Found a contact between ‘panda_link8’ (type ‘Robot link’) and ‘panda_hand’ (type ‘Robot link’), which constitutes a collision. Contact information is not stored.
[ INFO] [1628173366.292272163, 158.484643912]: Collision checking is considered complete (collision was found and 0 contacts are stored)
[ INFO] [1628173366.292302264, 158.484643912]: Start state appears to be in collision with respect to group panda_arm
[ WARN] [1628173366.326134548, 158.539172911]: Unable to find a valid state nearby the start state (using jiggle fraction of 0.050000 and 100 sampling attempts). Passing the original planning request to the planner.
[ INFO] [1628173366.326817695, 158.539172911]: Planner configuration ‘panda_arm’ will use planner ‘geometric::RRTConnect’. Additional configuration parameters will be set when the planner is constructed.
[ WARN] [1628173366.327349362, 158.539172911]: RRTConnect: Skipping invalid start state (invalid state)
[ WARN] [1628173366.327419452, 158.539172911]: RRTConnect: Skipping invalid start state (invalid state)
[ WARN] [1628173366.327498493, 158.539172911]: RRTConnect: Skipping invalid start state (invalid state)
[ WARN] [1628173366.327559874, 158.539172911]: RRTConnect: Skipping invalid start state (invalid state)
[ERROR] [1628173366.327615935, 158.539172911]: RRTConnect: Motion planning start tree could not be initialized!

After some digging, the cause is that the latest ROS melodic franka_description package has in the urdf a link ‘arm_link8’ with collisions defined. However, the collisions don’t exist in the Isaac example urdfs: (omni.isaac.urdf/data/urdf/robots/franka_description/robots/panda_arm.xacro).

Removing the collisions from the ROS franka_description package seem to temporarily fix the issue and motion planning works.

Thanks @SnehalJauhri, I’ve filed a bug and we will look at the best way to resolve this for the next release. One option is to not flatten the series of fixed joints in the urdf to preserve these joints.