Bypassing the computer of an old Kuka.

    I am sure this is possible but not sure how to get started. I have some old GM Kuka press robots. I would like to use as a manipulator/ heavy lifter. What I mean is no control or computer, just switches (joysticks) servos and motors. Similar to a hydraulic system of an excavator or boom truck, where all movements are from me pushing levers only. Does anyone have experience/wisdom of how to communicate with these Lenze drives? I would need to know how to control brake on/off, forward/ reverse, speed, and limits. Please no lectures on safety just helpful information. Thank You.

    First off, what model controllers? What hardware do they have internally?

    It might be possible, but I'm not sure what it would take. Assuming KRC2 or KRC1A, the servo amps are Lenze modules, mostly the same as Lenze modules made for CNC machines, but modified firmware for KUKA. They communicate via Interbus. If you can reverse-engineer them sufficiently, you might be able to drive the Lenze modules directly over Interbus. But getting to that point is going to be hard, unless you could get in-depth tech support from Lenze.

    More directly, the robot servos are just re-labelled Siemens motors, so you could in theory power/drive each motor directly. But that would require buying your own servo controllers.

    isn't that the most cost effective option? reverse engineering communication is possible but it is going to cost you much more, and that is if you already know what to do. And all this for something that is long retired is ... not very reasonable. if Win95 is the really so much of a problem, maybe explore options to turn it into KRC2 (they use same drives).

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    Thanks for the input. I welcome looking at all of the options. It is my understanding that these GM boards can not be upgraded to anything beyond win 95. My "simple" thinking was "these are just drives and motors, give them the signal they need and they will move" Apparently it isn't quite that simple. But keep in mind I am no looking for a fully functioning robot that works by itself as most robots do, I am just trying to get it to move while I hold a button. The goal is to "uncomplicate it", and maybe have something at least some what useful. But like anything else, one has to decide where their time is best spent. Thanks

    A power supply for the motors (not the same on all axes so you might need 2) and maybe one for the brakes, lots of switches (at least 12 with multiple contacts for activating the brake at the same time you want to move the motors on both directions). That's it. BUT!!! You will need 3 phase power for motors and you will not be able to control the speed so expect lots of nasty crashes. The instant you press the button it will fly off at max power and speed. Or use 6 VFD if you think that is viable.
    Anyway, no easy solution by any means, so back to win95 ! :smiling_face:
    Tom

    Quote from tommylight


    A power supply for the motors (not the same on all axes so you might need 2) and maybe one for the brakes, lots of switches (at least 12 with multiple contacts for activating the brake at the same time you want to move the motors on both directions). That's it. BUT!!! You will need 3 phase power for motors and you will not be able to control the speed so expect lots of nasty crashes. The instant you press the button it will fly off at max power and speed. Or use 6 VFD if you think that is viable.
    Anyway, no easy solution by any means, so back to win95 ! :smiling_face:
    Tom

    Well, the crashes can be avoided by simply using a potentiometer or stepwise resistor to give a fixed reference to the drives. Also, at drives end you have to see what hardwired setpoint they accept (4 to 20 mAmp or 0 to 10 VDC). I guess it should be 0 to 10 VDC. Once in our midterm engineering project, I made something like this to control three motors on VFDs using a single speed reference source. In my opinion, it worth trying if you have time and money to spend on required resources.

    Thanks

    Is possible but not simple. Lenze drives communicating Interbus with Robot controller system and telegram is special for KUKA. Firstly you should be solve interbus telegram and emulate in your own controller. Another subject is Resolvers; you need resolver converter for controller or solve RS485 communication of RDW. I think is taking long time and effort.


    I had change long time ago KUKA robot to Siemens Sinumeric system. But I use only motors on manipulator and I change drives, controllers and computer system for special application. This mean I didn't use KUKA controller. Sinumeric system is very expensive and I can buy a lot of KUKA controller.

    A power supply for the motors (not the same on all axes so you might need 2) and maybe one for the brakes, lots of switches (at least 12 with multiple contacts for activating the brake at the same time you want to move the motors on both directions). That's it. BUT!!! You will need 3 phase power for motors and you will not be able to control the speed so expect lots of nasty crashes. The instant you press the button it will fly off at max power and speed. Or use 6 VFD if you think that is viable.
    Anyway, no easy solution by any means, so back to win95 ! :smiling_face:
    Tom

    In this reply it sound like you are saying "wire up the motors but not use the drives"? I was thinking I would still use the drives to control the brake, ramp, and speed, . That is where I am stuck. I have talked to Lenze. They said (without trying too hard) that these are special "Kuka" drives and they didn't know what signals they needed.
    My thinking is still: These drives just need some type of signal to tell them to put out power to the motor.......But what type of "signal" do these drives need for "input" to get them to "output" power to the motor?????? That seems to be the mystery :help:
    Is there anyone who know what signals these drives are looking for? :wallbash:

    Agian....I am not looking to make a new robot with a "control" or "PLC". I just want to physically push a switch with my hand to get the robot arm to move. Thanks

    Interbus S is an industrial fieldbus. It's well documented.

    The bigger issue is the command protocol for the Lenze modules. First, the the Lenze modules are not standard, but customized for KUKA. So some way to duplicate that command protocols would be required.

    Power-banging servo motors is not advisable. For one thing, the resolvers are electrically interconnected with the drive coils for phasing -- I learned this the hard way when attempting to replaced the motor resolvers with an external resolver that perfectly mimicked the normal resolver signal.

    Thanks for the replies (long ago). I am revisiting this same idea, but thinking as simple as possible......without the drives.
    Is it possible to use the existing ac servo motors, but with a simple way to vary their speed ? Not necessarily infinite speeds like with a VFD or servo amp but simply low, medium, and high. At the end of the day all I need to do is take off the brake, and spin the motor at 3 different speeds in forward and reverse. I have concluded that trying to communicate with the existing drives/amps is very complicated and not required for the simple task I am try to achieve.
    Thank you again for spending your time on this "hair brain" idea.

    Quote from rgtxa


    Is it possible to use the existing ac servo motors, but with a simple way to vary their speed ?

    yes - by coupling motors with drives.

    servo motors such as 1FK7xxx are synchronous servo motors. this means they run in phase with ac signal that is powering them. to change speed, frequency must change. line frequency is fixed to 50 or 60Hz depending on country. in order to vary speed, frequency must change. you can think of KPC as function generator and drives as amplifiers.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

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    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    Is it possible to have 1 VFD for all of the motors, so they all run at 30 cycles, then you step on the gas pedal and they all run at 60 cycles ? Or do they each need to have their own drive? I want to turn them on and off manually with switches or relays not a computer.

    One of the main reasons I want to bypass the current control is when manually jogging in t1 or t2 it is too slow. Is there a way to speed up these speed limits in manual mode.....Yes I know it is not safe or recommended.

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