[ros-users] Odd delay between openni_tracker and teleoperation of robot

[Patrick Goebel]

Hello All,

I'm trying to teleoperate a robot that uses Dynamixel AX-12+ servos 
using a Kinect and the openni_tracker node.  I'm posting here instead of 
ros-kinect because I don't think it is a Kinect or OpenNI issue.  I use 
tf.TransformListener in my Python joint controller program and map 
skeleton frames from openni_tracker into translations and rotations of 
the joints.  If I do everything in RViz on my virtual URDF robot model, 
there is no delay between my movements in the Sample-NiSimpleViewer and 
the robot in RViz.  However, when I connect the real robot using a 
USB2Dynamixel, there is a delay of 3-5 seconds between my movements and 
the robot's movements.

The USB2Dynamixel is hardwired to both the robot and the controlling PC 
so there is no wireless link involved.  I am running the ArbotiX ROS 
package to control the servos and my servo polling rate is 15Hz.  I am 
running the joint controller node also at 15Hz and it publishes 
JointState commands at that rate to the servo controller.

Does anyone have an idea where the delay might be seeping in?  I'm happy 
to provide more details if needed.

Thanks!
Patrick Goebel

Behavioral Sciences
Stanford University