KRC 4 online path optimization Help!

  • Hi All;

    I have tig welding project and customer wants to edit path while welding in AUT mode;
    Using tool_corr.y variable and 2 buttons to change path in AUT mode but this system reacts too late cause of the tool correction variable changes the next command . Therefore our welding quality decreases.
    Dear PROS do u have any alternative and faster ways to compansate path in aut mode except laser tracking.

    thx in advance.

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  • The root problem here is that, once a motion from Point A to Point B begins, changing the Tool or Base data have no effect until after the robot reaches Point B. In fact, with the Advance pointer (which is necessary for smooth approximation between points), it's more likely to not have any effect until after the robot has passed from Points A,B,C, and D to Point E (depending on the value of $ADVANCE).

    One method would be to break the weld path up into many, much smaller, motions. That would at least allow changes to Tool or Base to take effect after less travel distance, although the number of points between making the change and its taking effect would be unchanged.

    Aside from that, really the only way to control a path as it is executed is to use some sort of realtime motion control layer -- the Function Generator or RSI. And those require some sort of realtime input, either sensors or manual controls.

    I'll ask the obvious question: why do you need to make these adjustments on the fly? Why isn't the part or tool consistent? You'd be far better off fixing that problem than attempting to make the robot blindly correct path motions on the fly.

  • First of all thx for your reply;

    Sry forgot the right down KSS (8.3.20). Value of the $advance=1 and Teach the positions 1 degree for all circular points.(Circular pipe welding with 5 pass).
    The answer of your obvious question is that our customer wants to compensate the path while watching the welding.Cause they can not manufacture the pipe consistent.And also I think Arc Voltage Control is not just controlling the height it also moves the robot to the left and right sometimes therefore ı have to make adjustments on the fly.

    I dont have much experience on RSI but can u give me any hint about function generator. Could it be helpful on my problem.
    thx in advance have a nice day

  • The Function Generator is not very well documented, but is the underlying technology that enables the ArcTech seam tracking to work. It's like a more primitive version of RSI. Put very simply, it allows a pre-programmed motion to be adjusted on the fly by realtime sensor inputs (although only in XYZ, no orientation changes). So, if you have a seam-tracking sensor of some kind, and program a straight weld path from Point A to Point B, the Function Generator can keep the robot following the seam even if it makes an erratic path from A to B.

    But it still requires some kind of sensing. Seam-tracking welding is outside of my area of expertise, but supposedly one of the more advanced ArcTech packages is supposed to be able to perform this sensing through the welding wire. But I've heard mixed reviews about how well it works.

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