Results 1 to 14 of 14
  1. #1
    kuraki556 is offline Cast Iron
    Join Date
    Aug 2010
    Location
    WI
    Posts
    389

    Default PC based robot control?

    My company is getting rid of an older Fanuc welding robot. I operated it a little, a long time ago, and could teach points but that was the extent of my experience with it. The arm is sound, but the control "had smoke coming out of it the day they took it down and it would barely weld."

    I could buy it for a price low enough to just play with, on my own, to learn more about robotics and test some automation ideas myself, but I'm curious if I can move to a newer/cheaper/easier/non-fanuc control? Am I right in my thinking that the robot is just servos and encoders, and telling it where to go and when to go there, should be relatively simple to retrofit?

  2. #2
    doug6949 is offline Hot Rolled
    Join Date
    Feb 2007
    Location
    Georgia
    Posts
    728

    Default

    The question you have to answer is where the smoke came from. If the servo drives are toast then you could be looking at serious cash or lots of scrounging to get the motors turning again.

    The control part is easy as there are several PC based CNC/robotics programs, many of which are free and open source. The best of these is emc2 but it runs under linux.

    Implementing linux and emc2 depends on your aptitude for programming. The pre-configured setups are easy. None exist for a welding robot that I am aware of.

    Mesa Electronics, Pico Systems, and others sell boards that should directly interface with the Fanuc servos and various control circuitry.

    All the cheap or free windows/DOS software is intended for step motors. The workarounds for servos defeat the purpose of having servos and will cost more than the Mesa cards.

    Doug

  3. #3
    JHOLLAND1's Avatar
    JHOLLAND1 is online now Titanium
    Join Date
    Oct 2005
    Location
    western washington state
    Posts
    2,243

    Default

    of all industrial level machine tools, the multi-axis robot has the poorest resale/residual
    value . i have owned a good dozen, made money on maybe two of these. parting them is usually what happens. now if you find the rare "P" series Fanuc, working, you've got something.
    we have experience in retrofits up to 8 axis. but retrofit software for multi-axis robots is mostly high end european. or Fanuc. entry level $40K. add another $20K for install.
    eventually game control software (x-box, playstation) will be adapted to robot retrofits. integrating encoder feedback, from 8 servos all in motion, will be a trick though. many US based robot retrofitters have folded.

    jh

  4. #4
    3t3d is offline Titanium
    Join Date
    Nov 2004
    Location
    WI
    Posts
    3,771

    Default

    On an RJ2 control, the drivers do not have any commutation logic in them. They get six inputs for the three phase H-Bridges for each of the individual axes.

    The computer boards have the encoder inputs, and do all the commutation calculations, along with motion and trajectory calculations.

    If you are a super software guru, and dedicate yourself to software Development, not software re-purposing, then, just maybe you could do it, once you became a hardware guru, and designed the commutation circuitry, and encoder counters and interfaces.

    Or you could cruise ebay, and find some new/used boards for the control, and THEN ASSUMING you could dig the software intact out of the dead control, you could boot it up.

    Otherwise plan on spending MORE than the robot is worth, to "license" the software in the robot from Fanuc. You need to "license" the software before they will answer ANY questions about it. They will not even sell you parts, or look up part numbers, or verify any part numbers.. Nothing. Even if the previous owner was properly "Licensed", once the robot changes hands, you need to pay Fanuc again, every time the robot changes hands.
    This is how it was explained to me, anyway, by Fanuc.

  5. #5
    Stuart Caruk is offline Hot Rolled
    Join Date
    Feb 2007
    Location
    Ridgefield, WA
    Posts
    992

    Default

    You're not going to find a CHEAP PC based solution to running a Fanuc robot. It's not even worth trying, you can buy an ArcMate with a welding power supply delivered for under $7k if you watch Ebay. I've got 3 of them this way, and they all work just fine. You couldn't even to begin to interface 1 for that price. If I were you I'd fix the existing control, or part it out and go buy another used working system.

  6. #6
    doug6949 is offline Hot Rolled
    Join Date
    Feb 2007
    Location
    Georgia
    Posts
    728

    Default

    Quote Originally Posted by 3t3d View Post
    On an RJ2 control, the drivers do not have any commutation logic in them. They get six inputs for the three phase H-Bridges for each of the individual axes.

    The computer boards have the encoder inputs, and do all the commutation calculations, along with motion and trajectory calculations.
    Well, that sucks. The OP was really just looking for something to tinker with but I can't see much excitement to be had with a boat anchor. Looks like Fanuc went to great effort to make sure these robots would not be retrofitted. Yup, that sounds like Fanuc alright.

    Doug

  7. #7
    skunkworks is offline Aluminum
    Join Date
    Aug 2007
    Location
    Holmen, Wi
    Posts
    138

    Default

    Actally - emc could do this also.. One of the developers has created a bldc component that will pretty much do anything... (right down to controlling h-bridges directly)

    BLDC

    there have been a few people using them now..

    As far as the arm itself. Emc2 does have serial kins that works with serial stacked arms. You give it arm lengths and offsets and it does the joint to world conversion. Not for the faint of heart but quite a few people have been using it.

    sam

  8. #8
    Zahnrad Kopf's Avatar
    Zahnrad Kopf is offline Stainless
    Join Date
    Apr 2010
    Location
    Tropical Milwaukee, WI
    Posts
    1,860

    Default

    Quote Originally Posted by skunkworks View Post
    Actally - emc could do this also.. One of the developers has created a bldc component that will pretty much do anything... (right down to controlling h-bridges directly)

    BLDC

    there have been a few people using them now..

    As far as the arm itself. Emc2 does have serial kins that works with serial stacked arms. You give it arm lengths and offsets and it does the joint to world conversion. Not for the faint of heart but quite a few people have been using it.

    sam
    That answers/addresses a thought/ponderance/musing I've been toying with of late - Been getting ready to convert a machine and been thinking of using a small robot arm to function as a tool changer... Drat... now I hafta spend money...

  9. #9
    Miguels244 is offline Titanium
    Join Date
    Mar 2011
    Location
    Denver, CO USA
    Posts
    3,770

    Default

    Quote Originally Posted by skunkworks View Post
    Actally - emc could do this also.. One of the developers has created a bldc component that will pretty much do anything... (right down to controlling h-bridges directly)

    BLDC

    there have been a few people using them now..

    As far as the arm itself. Emc2 does have serial kins that works with serial stacked arms. You give it arm lengths and offsets and it does the joint to world conversion. Not for the faint of heart but quite a few people have been using it.

    sam
    Does it handle the full Denavit, Hartenberg analysis?

  10. #10
    <jbc>'s Avatar
    <jbc> is offline Stainless
    Join Date
    Jun 2011
    Location
    Switzerland
    Posts
    1,839

    Default

    There is the Orocos project.

    The Orocos Project | Smarter control in robotics & automation!

    It would be a good starting off point for Post-Graduate research in Mecatronix.

    Its built upon a hard-realtime kernel, a requirement for robotics that a PC does not fulfill.

    Cheers
    <jbc>

  11. #11
    skunkworks is offline Aluminum
    Join Date
    Aug 2007
    Location
    Holmen, Wi
    Posts
    138

    Default

    as I understand it - yes.

    Puma 560 3D model (I am the samco he is talking about.. Yes I need to get the arm running.. Some day)

    Quote Originally Posted by Miguels244 View Post
    Does it handle the full Denavit, Hartenberg analysis?

  12. #12
    skunkworks is offline Aluminum
    Join Date
    Aug 2007
    Location
    Holmen, Wi
    Posts
    138

  13. #13
    skunkworks is offline Aluminum
    Join Date
    Aug 2007
    Location
    Holmen, Wi
    Posts
    138

    Default

    Emc2 runs on a special real-time patched kernel. (Rtai is the main one) Some consider that hard real-time. (I don't have the knowledge to weigh in on that argument.)

    sam

    Quote Originally Posted by <jbc> View Post
    There is the Orocos project.

    The Orocos Project | Smarter control in robotics & automation!

    It would be a good starting off point for Post-Graduate research in Mecatronix.

    Its built upon a hard-realtime kernel, a requirement for robotics that a PC does not fulfill.

    Cheers
    <jbc>

  14. #14
    doug6949 is offline Hot Rolled
    Join Date
    Feb 2007
    Location
    Georgia
    Posts
    728

    Default

    Quote Originally Posted by skunkworks View Post
    Emc2 runs on a special real-time patched kernel. (Rtai is the main one) Some consider that hard real-time. (I don't have the knowledge to weigh in on that argument.)

    sam
    Whether or not the PC is capable of 'real time' control depends on one's requirements. If the update rate and jitter limitations are satisfied then it is capable of real time motion control. The PC does this very well as evidenced by the fact that some very high performance commercial controls are PC-based.

    The 'not-real-time' argument didn't exist prior to the widespread acceptance of NT and its descendants. Suddenly, the X86 interrupt architecture was found to be wholly inadequate for real time control applications.

    Fortunately, nobody has informed the bumblebee that it is mathematically impossible for him to fly.

    Doug

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •