Assistance Needed: KUKA iiwa Arm Simulation and Collision Sphere Configuration Issues

Hello,

I’m attempting to simulate the movement of a KUKA iiwa robotic arm using NVIDIA Isaac SIM and have encountered two issues that I need help with:

(1) I have sourced the KUKA iiwa URDF file from ROS-Industrial’s GitHub (kuka_experimental/kuka_lbr_iiwa_support/urdf at melodic-devel · ros-industrial/kuka_experimental · GitHub) and generated a YAML file using the Lula Robot Description Editor. Following the LULA tutorials in Isaac, I configured ArticulationKinematicsSolver and LulaKinematicsSolver for TCP control. However, I am facing an issue where the end-effector cannot reach some positions that should theoretically be accessible, and the system throws a “PhyaX error: Illegal BroadPhaseUpdateData” error. It seems to be a problem with the inverse kinematics calculations, but I am unsure how to resolve this.

(2) Following tutorial 6.1 from Isaac (6.1. Lula Robot Description Editor — Omniverse IsaacSim latest documentation), I tried to add collision spheres to the KUKA model but was unable to select any links. Even when I forcibly add collision spheres, they do not appear in the collision_spheres section of the exported YAML file. I even tried using the built-in Omniverse Franka model and encountered the same issue.

Do you have a pre-configured KUKA model that you could share? Or any advice or solutions for the issues described above? Thank you very much for your assistance.

Best regards,
Yanbing