Loop rate for control position


Hi everyone!

Recently our research group bought Dynamixel motors and a 3D printer in order to assembly the humanoid Poppy robot.
We are interested in high performance for balance task. What is the max loop rate that the Pypot library gets for 25 Dynamixel motors (baud = 1Mbs) using two USB2AX using position command?

There are options as Dynamixel Workbench (ROS), Dynamixel_motors (ROS) or Pypot. I am really interested in using Pypot.





With Pypot, with the ODROID U3, reached a framerate of 50Hz. I had 20ms to make optimisation work which is sufficient. But the difference between 50Hz and 25Hz on the mechanics is the same. 25Hz is sufficient and 40ms to make optimisation is largely sufficient.
With the new generation boards, it is difficult to reach these rates (I am still investigating)
With RPi3+, I cannot reach these rates for the moment with pypot.
I have installed a Up Board (4Go RAM with emmc) in the head and it is really better (but not the quality of the old ODROID U3)
I tried the Dynamixel ROS package, but it is half done. It cannot detect any unplugged motor.
maybe my next step is to look at the dynamixel SDK, treating case of FTDI driver issues on Linux.

Here is where I am :slight_smile:


Thomas, Thank you for your answer. Have you performed tests using a desktop computer (Intel core i7 quadcore ~2-3 GHz) ?


Yes, these two robots were based on classic desktop computers but on windows.


And the matching code for the poppy kinect install


Thomas, thanks.
I’ll test the PyPot library. I agree, Dynamixel ROS package is half done. With respect to Ros packages, Do you tested both?
(http://wiki.ros.org/dynamixel_motor) (http://wiki.ros.org/dynamixel_workbench).


No only the first one. I am thinking about making a ROS node for dynamixel (the simplest as possible)