[panda] joint limits do not match the specification

[squizz617]

Hi.

The joint limits defined in the URDF of the panda manipulator are either (1) different from the specification or (2) slightly exceed the specified min/max.

Expected (as per the datasheet provided by the manufacturer):

• joints 1, 3, 5, 7
  • [-166:166] deg
• joint 2
  • [-101:101] deg
• joint 4
  • [-176:-4] deg
• joint 6
  • [-1:215] deg

Defined soft lower and upper limits:

• joints 1, 3, 5, 7
  • [-2.8973:2.8973] rad = [-166.003062:166.003062] deg
  • exceeds the limit by 0.003 degrees
• joint 2
  • [-1.7628:1.7628] rad = [-101.001:101.001] deg
  • exceeds the limit by 0.001 degrees
• joint 4
  • [-3.0718:0.0175] rad = [-176.0011:1.00267] deg
  • upper limit is WRONG; difference is 5 degrees
  • lower limit exceeds the spec by 0.001 degrees
• joint 6
  • [-0.0175:3.7525] rad = [-1.00267:215.0024] deg
  • exceeds the limit by 0.002 degrees

Could you consider fixing these? Thank you.

[rhaschke]

Thanks for the hint! Could you please file a pull request to fix those? Note that this is not the official URDF of the Panda robot, but one that is used internally in MoveIt CI. For the official version, see https://github.com/frankaemika/franka_ros/tree/noetic-devel/franka_description

[rhaschke]

@squizz617, do you plan to submit a PR to fix this? If not, I'm tempted to close this.

[squizz617]

Hi @rhaschke, I've opened #118 for this. Thanks!

BTW,

this is not the official URDF of the Panda robot, but one that is used internally in MoveIt CI.

this URDF is being used in the tutorials, where it mentions that "the Franka Emika Panda robot is used". So I assumed this file was the official one.