Hi,

I'm currently trying to figure out how to handle multiple robots in Gazebo and I ran into this bug(?):

header: 
  seq: 12209
  stamp: 
    secs: 330
    nsecs: 109000000
  frame_id: ''
name: ['kuka_lwr_joint_1', 'kuka_lwr_joint_2', 'kuka_lwr_joint_3', 'kuka_lwr_joint_4', 'kuka_lwr_joint_5', 'kuka_lwr_joint_6', 'kuka_lwr_joint_7', 'omnirob_base_joint_theta', 'omnirob_base_joint_x', 'omnirob_base_joint_y', 'powercube_joint_pan', 'powercube_joint_tilt', 'schunk_pg70_joint_left_jaw', 'schunk_pg70_joint_right_jaw']

position: [-1.0253947033689315e-05, 2.3522499048134193e-05, -2.2689813867771136e-05, 2.3136640944443343e-05, -1.0738741315741152e-05, -2.483711961254187e-05, -5.4067762246035045e-05, -5.224777055445884e-09, -2.7112045384056236e-12, 1.0643540367097492e-13, 8.826312682153059e-05, 7.902852640739866e-06, -2.807751732313897e-09, 4.075292461219283e-09]

velocity: [-4.178236861677637e-06, 0.0033800355546081623, 0.0001795040668656702, -0.0010695986716272555, -3.479691430856919e-05, -0.0013532377287914495, 1.842815311281211e-05, 5.6265612727336565e-06, 9.567045326563722e-08, -2.767842212481839e-08, 7.332785746463743e-05, 0.004272763884220085, 2.2936775146593057e-05, -2.2746741801888933e-05]

effort: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
---
header: 
  seq: 2452
  stamp: 
    secs: 330
    nsecs: 121000000
  frame_id: ''
name: ['omnirob_base_joint_x', 'omnirob_base_joint_y', 'omnirob_base_joint_theta', 'kuka_lwr_joint_1', 'kuka_lwr_joint_2', 'kuka_lwr_joint_3', 'kuka_lwr_joint_4', 'kuka_lwr_joint_5', 'kuka_lwr_joint_6', 'kuka_lwr_joint_7', 'schunk_pg70_joint_right_jaw', 'schunk_pg70_joint_left_jaw', 'powercube_joint_pan', 'powercube_joint_tilt']
position: []
velocity: []
effort: []

This first message is composed by Gazebo, the second by the jointstatepublisher. Now if I run my simulation for the single robot setup(which does not include support for ROS_NAMESPACE), the messages look like this:

header: 
  seq: 1
  stamp: 
    secs: 205
    nsecs: 728000000
  frame_id: ''
name: ['omnirob_base_joint_x', 'omnirob_base_joint_y', 'omnirob_base_joint_theta', 'kuka_lwr_joint_1', 'kuka_lwr_joint_2', 'kuka_lwr_joint_3', 'kuka_lwr_joint_4', 'kuka_lwr_joint_5', 'kuka_lwr_joint_6', 'kuka_lwr_joint_7', 'schunk_pg70_joint_right_jaw', 'schunk_pg70_joint_left_jaw', 'powercube_joint_pan', 'powercube_joint_tilt']
position: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
velocity: []
effort: []
---
header: 
  seq: 2
  stamp: 
    secs: 205
    nsecs: 828000000
  frame_id: ''
name: ['omnirob_base_joint_x', 'omnirob_base_joint_y', 'omnirob_base_joint_theta', 'kuka_lwr_joint_1', 'kuka_lwr_joint_2', 'kuka_lwr_joint_3', 'kuka_lwr_joint_4', 'kuka_lwr_joint_5', 'kuka_lwr_joint_6', 'kuka_lwr_joint_7', 'schunk_pg70_joint_right_jaw', 'schunk_pg70_joint_left_jaw', 'powercube_joint_pan', 'powercube_joint_tilt']
position: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
velocity: []
effort: []

As you can see the difference between those message is the order of the joints and the missing positions in the message from the jointstatepublisher.

Gazebo itself is started outside the namespace.

Why does Gazebo change the order of the names when I export a ROSNAMESPACE? And does this affect the jointstate_publisher?