SRVO - 050 Collision Detect Alarm (G:1 A:6) - RJ3iC 120iB/10L a

    We have a Fanuc robot(RJ3iC 120iB/10L) at our facility that we love working with. These past few weeks it started giving the SRVO - 050 collision detect alarm (g:1 a:6). We get this alarm only when manually jogging the robot. In Joint Mode, all axis rotate as expected except for axis 6. Axis 6 rotates very little only at "fine" speed for a small second and alarm goes on. However, if we are running a program, we don't have any alarm codes and axis 6 works.

    We have tried lowering the sensitivity of collision guard. It allowed moving axis 6 a little more at "1%" speed. We then greased all axis, thinking it was causing the issue as well, but no luck. Has anyone come across a similar issue? Any suggestions?

    Thank you,

    Burcin Nalinci

  • Go to Best Answer
    Quote from pdl

    Is your payload properly set?

    Have you had any hard crashes lately?

    Thank you pdl,

    No hard crashes. Haven't adjusted the payload. It was working as of a few weeks ago with same settings. I am worried it might be the brakes not releasing properly but not sure how to diagnose for it either.

    Hi pdl

    I'm working with burcinnalinci on this robot.

    No active payload - nothing attached to the end of the robot. Schedule attached.

    J6 moves fine while executing a program but immediately throws alarm when jogged. I have disabled COLL GUARD and also tried it at 1% sensitivity - but still the immediate alarm.

    Could it be a velocity/acceleration setting somewhere? Over speeding J6 during a rapid jog?

    Thanks for your help!

    In general should be used SK-3 because there's a harmonic reducer.

    I have no idea whether it's the friction issue or not, many things could be.

    Recently I have such a similar case but with J3 and also have no idea what's going on (still fighting with it).

    Do you have a spare motor? Maybe exchange it and check - there could also be a problem with motor.

    Quote from neighbour1

    In general should be used SK-3 because there's a harmonic reducer.

    I have no idea whether it's the friction issue or not, many things could be.

    Recently I have such a similar case but with J3 and also have no idea what's going on (still fighting with it).

    Do you have a spare motor? Maybe exchange it and check - there could also be a problem with motor.

    Unfortunately I don't have a spare on hand. The fact that it works while executing a program but doesn't while jogging feels like the clue.... what it means..? :thinking_face:

    • Best Answer
    Quote from burcinnalinci

    We get this alarm only when manually jogging the robot. In Joint Mode, all axis rotate as expected except for axis 6. Axis 6 rotates very little only at "fine" speed for a small second and alarm goes on. However, if we are running a program, we don't have any alarm codes and axis 6 works.

    How much displacement occurs with JT6 when running in repeat mode?

    Can you replicate the error in repeat mode by running it at a lower speed?

    Can you replicate it in repeat mode around the same locations in the program?

    Have you thought of creating a standstill test program to just exercise JT6?

    IMHO it sounds like you have reducer issues at JT6 and no amount of playing with settings will resolve it.

    - Cross roller bearing damage.

    - Harmonic wave generator/flex spine damage.

    - Too much lubricant.

    Quote from RockemSockem

    FANUC lists both Molywhite RE-00 and SK-3 as acceptable greases for the harmonic drive on the 120iB. Their bulletin (#03409)actually states you can even have both in the drive without issue, which is pretty neat.

    In general yes, you're right. But even when you look at the sticker close to J6 reducer, it's written SK-3, right? So I always use it, also because right now Molywhite is replaces with Vigo, so I have no Molywhite on stock, and it's used not so often.

    Turns out it was a grease distribution problem - we wrote a routine that exercised J6 slowly working up rotations and speed. After running it for 10 minutes we were able to successfully jog. Interesting to learn how much more sensitive the torque sensing is during jogging vs program running. I guess it makes sense, they assume during operation you have a better idea where the robot will be than during jogging.... :icon_eek:

    Quote from neighbour1

    Swap J5 motor with J6 motor - it's the same.

    Then check whether the error migrates to J5 or not.

    This is a great tip - I'll remember it if we run into any more trouble!

    Quote from RockemSockem

    OK. I just wanted to clarify that the problem doesn't have anything to do with the type of grease used.

    Molywhite RE-00 is written on the side of the axis (original fanuc plaque/label) so we just followed that! Maintenance has been neglected on this bot - grease looked only slightly yellowed but properties must have changed while sitting idle.

    Thanks for all the help everyone - :beerchug:

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