youbot_oodl interrupted by gripper readings

[eliasm]

We recorded the ROS topic "joint_states" and find that no message arrives during regular time intervals. We could isolate the issue to be the gripper sensor readings:
https://github.com/youbot/youbot-ros-pkg/blob/master/youbot_drivers/youbot_oodl/src/YouBotOODLWrapper.cpp#L868

You can reproduce the error by simply looking at the frequency of the youbot_oodl:
$ rostopic hz /joint_states
You will see that the frequency is not at 50Hz (the default value for the youbot_oodl), but around 40Hz. If you look at the data, you will see something like in this plot:

As a workaround we just commented out these lines. A possible fix to this issue would be to put the sensor readings of the gripper to a separate thread that does not block the main thread.

[pietrofalco]

Hi Eliasm,
thanks for sharing this issue. We had a similar problem and I'll try to fix it in the way you propose.
Do you also know if it's possible to increase the frequency of the topic "joint_state". I tried to modify the parameter "youBotDriverCycleFrequencyInHz" of the youbot_oodl but nothing seems to change...

Thanks,
Pietro

[frederikhegger]

We also experienced this and try to address this also in the following pull request: https://github.com/youbot/youbot_driver_ros_interface/pull/8/files