Joint move not returning fourth axis

    We have some brand new M-710iC/50 robots with R30B controllers. When we teach a joint move position with our other robots the robot will always return all 6 axis's to the same position when told to go to that position.
    On these robots after we teach a joint position and then move the 4th axis (which turns the end effector) when we tell it to go back to the taught position the 4th axis stays turned and the 6th axis rotates. The end effector is in the same position as taught but the 4th and 6th axis are not the same. This is a concern because when we return to the taught position normally all the axis's return to the position as taught and keeps all the cables from getting wound up.

    Any ideas. I thought any taught Joint move always keeps the same configuration when returning to it.

    Are you moving to it in a program or moving to it by hitting 'move to' on the teach pendant. Either way, its moving in linear (not joint) and the end resultant tool center point position is exactly the same even though the arm representation is not. You might be jogging in joint, but your moving in linear.

    Petewalz:

    TRBe is correct.
    This happens also with other robots, specially if you are close to singularity.
    I'm glad you saw it because it could be running ok for years, but if somebody touches up (even for 1/2 degree) the points you could be ripping the harness apart.

    Even that is fixable (following TRBe instructions), is there any way that you don't line up 4 and 6 so well ?

    TIP: It doesn't look very nice, but sometimes a add another point, just to "help the robot", indicating which way to rotate. Even a small motion will give the robot a clue which path to take

    Retired but still helping

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