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Externally Guided Motion [EGM] Bandwith - Experiences?

markus_g
markus_g ✭
in RobotStudio
Dear all, We have been working with ABB's Robot Reference Interface (RRI) -- which is the predecessor of the EGM -- to control our robot from an external Linux computer. Our experience with the RRI is that it provides very reliable data exchange at 250 Hz. Data from the robot, such as joint angles, can be read with a time resolution of 4 milliseconds. However, we found that a limiting factor for closed-loop control of the arm is the frequency with which the actual RAPID motion commands (e.g. MoveAbsJ()) can be updated in the Motion Task. Including the computing time that ABB's internal path planner requires, and other delays, we have only received effective update rates that were an order of magnitude lower than the maximum frequency of the RRI. In particular, in our current application, we have reached around 10 Hz of motion command update rate. While this update rate is enough for slow closed-loop positioning applications, we are wondering what the next generation interface, the EGM, will be able to achieve. According to the datasheet, it allows to bypass ABB's path planner, which is promising. For our application, we need to reach motion command update rates of at least 100 Hz or more. We can imagine that other users might have similar requirements for bandwidth. Does anybody have hands-on experience with the EGM and can make a statement about his experimentally achieved bandwidth? Has anybody compared it directly to the RRI? Any information with regards to that will be highly appreciated. Thanks a lot in advance! Best regards, Markus

Comments

  • Jaco Cronje
    Jaco Cronje ✭
    I have been able to move the robot with the mouse using EGM. The latency was around 40-50 ms before you see the robot move after the mouse has been moved. I had to use undocumented parameters for the EGM function that we somehow managed to get from ABB. There is a few parameters that can be tuned in order to improve the results for your own needs. EGM worked much better than RRI. With RRI we got around 450ms delay.
  • Scott
    Scott ✭
    What are those undocumented and how to tune them? Do you mind sharing with us?
  • kazoo
    kazoo ✭
    I'd like to know the parameter too. Please reply!

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