Got my hands on an old KUKA KR125 with KRC1 controller. Assessing possibillities

  • Hi All,


    My name is Maurits and I'm from Amsterdam, the Netherlands.

    I'm new to this forum as I've never done anything robot related other then some arduino programming for a toy 6dof ali-express robot. I do have quite some experience with generating multi axis CNC toolpath , so I'm somewhat familiar with machine programming. When I saw this huge robot-arm for cheap I couldn't resist getting it, not knowing anything about the state of the machine, or how to get it hooked up.

    I have done some research, downloaded the manuals, familiarized myself a bit so I think I'll just hook it up as soon as it arrives in my workshop and see what it does.


    In the meantime I'm studying the possibillities. Ideally I'd use it for sculpturing 3D models from EPS. I tried to figure out a workflow which I think I have now. I use fusion 360 to generate toolpath. I have a paid license, but without the manufacturing extension, so I can do 3+2 axis programming but not simultaneous multi-axis. That's fine for now, as I can still reach everywhere with 3+2. With the nifty RoboDK add-in I can port it to RoboDK where I can cimulate it and translate it to something the KRC1 should understand.


    I notice that the code gets very long very quickly. A simple 2D pocket of some letters on a 15" x 25" panel with a 1/2" bit gets converted into 2000+ instuctions. If I understand correctly I should avoid arcs and circles as they are translated into a bunch of points in space, whereas a line can be written in one instruction with a start and an end point (the controller does the math in deciding which motors to run at what speed to get there). So a big part of keeping it simple can be done in generating toolpath, but still that gives me 1500 instructions.


    So after this long intro I guess my question is: what can the KRC1 handle? Can I feed it a more complex file of, say, 50k+ instructions in about 2 hours? Can the processor keep up with this many calculations? Will the RAM be sufficient?


    Some of the limited known specs (I'll know more when its in my shop):


    type: KLR125

    controller: (V)KRC1 with PM6-600 (does this mean it has served at volkswagen?)

    processor: 433Mhz

    RAM: 192MB

    image version: 4.1.5

    OS: Windows 95


    After some reading on this forum I started by making a clone of the harddrive. I also have the original win95 installation disk.


    Is there any other advice of any sort you can give me?


    Many thanks for reading along. Hope to be learning lots here and someday maybe even be able to give somethoing back to the community.


    Cheers,


    Maurits

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  • HawkME

    Approved the thread.
  • KRC1... I'm not sure, honestly. But the memory limit will be low, probably single-digit MB. And one issue is that KRCs don't keep their programs on the hard drive until it's time to run them, it loads all of them into a RAMdrive. So you'll run out of memory long before running out of hard drive space.


    IIRC, there's also a limit for how many lines a program module can contain, and for a KRC1, it may be pretty low. You can probably code around that by having a "main" program that calls smaller "path" programs one after the other, which would allow you to avoid the per-module memory limit.


    There is a KUKA option program for "swapping" programs in/out of memory (the DirLoader), but I don't think it was supported on anything before the KRC2. Likewise, most of the options to "stream" data into the robot were never available for the KRC1. On a stock KRC1, your only options are probably the RS232 serial port, and (maybe) the MFC DeviceNet port.


    Reducing line count will probably be key. Using .SRC files with all the moves in the motion commands, like LIN {X 100,Y 250,Z 300, A 0, B 0, C0} will cut your line count by ~50%, compared to having LIN P1 in the .SRC and the definition of P1 in the .DAT.


    Anything that can get your CAM software to use lower point density on the output will be a good idea.

  • Thanks for the useful info! I should first see if I can get it up and running in the first place, and then I can start tinkering with code. I do like that streaming through serial port seems like an option. Is there some kind of handshaking protocol for dataflow management?


    Would only using G0 and G1 in my CAM software (and avoiding circle and arclike commands like G2 and G3) help so it just gives start- and endpoints of lines?


    Any last words before I hook up an old machine that potentionally has the power to tear down down the building and hasn't been used for years, with unknown condition? :smiling_face:

  • Thanks for the useful info! I should first see if I can get it up and running in the first place, and then I can start tinkering with code. I do like that streaming through serial port seems like an option. Is there some kind of handshaking protocol for dataflow management?

    Be advised: the KRC serial interface was never intended for realtime "streaming" control, and the robot-side programming would be a real exercise. And I barely remember anything about serial on KRC1s.


    To begin with, I would suggest creating a robot-side program with a large point array, and breaking your overall CAM program into smaller pieces, sized for the robot program/memory limit. Each pice would end at a position clear of the workpiece, then the point array could be wiped and refilled with data received over the serial port.

    Would only using G0 and G1 in my CAM software (and avoiding circle and arclike commands like G2 and G3) help so it just gives start- and endpoints of lines?

    That's probably going to be an near-necessity. To do anything beyong basic G1/G0 moves, you would have to use much more complex programming, and send a lot more data. For example, the KRL CIRC motion (the closest equivalent to a G2/G3) requires being sent two points to define the arc.

    Any last words before I hook up an old machine that potentionally has the power to tear down down the building and hasn't been used for years, with unknown condition?

    Safety.

    SAFETY.

    SAFETY.


    Depending on your specific KRC1, it will require 3-phase input power in the 380-575VAC range. This is hazardous. It's impossible to be too careful with this voltage.


    As you said, this robot is also physically dangerous when it moves. As such, it has multiple safety interlocks to try to make it more difficult to hurt yourself. But getting the robot to move at all depends on defeating these interlocks in a controlled fashion. For example, the Safety Gate interlock prevents the robot from operating in automatic modes, but allows Teach modes (where the robot can only move as long as someone holds the deadman switch). Normally, this interlock is linked to a gate in a safety fence, such that it it not possible to come within the robot's physical reach without opening the gate. It is entirely possible to wire this interlock permanently shut, but this creates a hazard that the robot could be left in automatic and take off at full speed without warning, while someone is close to it. And the robot can move much faster than humans can react.


    In the past 20 years, there have been only two confirmed cases of robot/human fatalities (that I am aware of). In both of those cases, the "victim" had defeated the Safety Gate interlock and moved into the robot's physical reach while the robot was still in automatic and energized.


    It's easy to say "Well, I won't be that stupid." I've been working with these machines for 30 years, and I'm still that stupid sometimes -- it only takes a moment of distraction or fatigue to make a potentially fatal mistake. Several times, I've only been spared severe injury (or worse) thanks to robust safety interlocks.


    Treat it more like a loaded firearm than a typical large power tool.

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