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PID Controller with IRC5

dam85
dam85 ✭
in Robot Controller
I must develop a system to plasma cutting with work height controller, I
have an analog input to measure arc voltage and i want modify z-Tool in
respons to this  voltage to keep costant the distance between gun and
piece.
I think to use Multitasking option and create one move task to
run all movement routine and a second static or semistatic task to
control arc voltage and keep distance.
I know that there are many
systems to do this ,like AWC , but I want develop my competitive system.

My
problem is to make routines with PID controller.

Has somebody already programmed this algorithm??

thanks

Comments

  • BigM
    BigM ✭
    Did u ever get a solution?
  • Laro88
    Laro88 ✭

    I tried to do some code that executed "fast" i another task since I expected the MultiTasking to be able to have a scan cycle of 50 ms or so. However it was simply too slow - my current scan cycle is about 300 ms.

    I will not put my head on the block for this, but the Multitasking is not intended for running regulation algorithms and such, rather simple parallel activites like IO operations, do some interrupt stuff and so on.

    You will most likely need a PLC, a realtime kernel somewhere or do as i do and execute the realtime code on a pc - and then live with the fact that is not hard realtime and design your system as such.

    Perhaps the new plc inside the cabinet has capabilities to interact with the robot, worth looking into.

    Laro882010-07-20 10:56:25
  • BigM
    BigM ✭
    I'd be interested at looking at your code for the PID if thats ok.
    I'm doing something similar to this and have used the software option "Path offset".  I generate a 10Hz interrupt which triggers a TRAP routine to look at the arc voltage, compare it to the set voltage for the cutting parameter and then move accordingly in the tools z-direction.
  • dam85
    dam85 ✭
    also I tried to program PID with an interrupt that monitor an analog input and modify z-tool but I need 6ms sampling time and without Multitasking option I can't sample the input in a time less than 30 ms.
    However I sample 9 signals, calculate mathematic avarage of these and applicate a PID regulation about this avarage.
    To program code I translate the discrete method PID controller in Rapid language.

    Now I'm trying to do this with an external PLC in DeviceNet that has within a PID function block.






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