RJ3-iB Robot slow down and Jerkieness

    We have 3 robot cells all with RJ3-iB Controllers and R-2000iA robots attached with servo guns for spot welding. Each cell has a controller that controls a turntable and 2 trunions. These controllers all seem to share the same problem. The teach pendants run very slowly and it can't even update the speed while running unless you mash the button continuously. All the menus take 5 seconds or more to load. One of the robots has also developed a very loud clunk noise whenever it makes linear moves. We know it is not mechanical because we switched robots out and the same thing is happening. It's like the robot can't process the data fast enough so it has to catch up and jerks around. We just increased the digital I/O from 64 points to 128 and that made the problem even worse. We are thinking it is a memory issue but fanuc says all our numbers look fine.

    Does anyone have any ideas what could be causing this issue?

    Edit: All the robots now have the large clunking sound and slowdown when changing the speed happening but it is only during a linear move. A program with all joint moves doesn't have any problems when we try to change the speed and no clunks.

    Edited once, last by naduley (February 20, 2013 at 7:45 PM).

    Yes, I know the problems. The program was written in KAREL and programmers sometimes will write in a line of code like this..

    REPEAT
    UNTIL DN[1] or DIN[2] OR BOOLVAR=TRUE

    what they miss is that this extremely tight loop eats up a ton of processing time on the CPU and so there isnt any time share left for the controller to read or write data out to the teach pendant to update it. No need to mash the button, it just simply has no time to talk to the TP.

    You need to edit the program and add a delay in the loop.

    REPEAT
    DELAY 20
    UNTIL (things your testing for to break out of loop)

    The 'clunk' sounds like it is the dampener cylinder that attatches to the lower portion of the 1st arm. The spring inside starts to clang against the housing over time. Make sure you have joint 2 at 0deg when you attempt to replace them, VERY DANGEROUS , they are like the suspension springs in a car. At 0deg all the pressure should be off of them.
    Just having this issue in linear makes no sense. Reducers failing??

    Good luck, let us know what you find. -Eric

    Edited once, last by Chipprogr (February 21, 2013 at 1:23 AM).

    We finally fixed the problem. It was a servo gun variable that we had to adjust. $SGDEFVAR ---> $ITP_TIME the default was 8ms and we had to increase it to 24ms and that solved all our slow down and clunking issues.

    sometimes when the robot it's too busy it has some delays opening screens, so, you need to check how many programs are you running at the same time, and how many you really need to run, maybe you can make some as macros for swing the turn tables or the trunions

Advertising from our partners