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Thread: Position Control with Proportional Valve

  1. #1
    Join Date
    Aug 2009
    Location
    ifm Exton, PA
    Posts
    196

    Default Position Control with Proportional Valve

    Here is an example of simple position control of an axis using a proportional valve with 2 coils. (extend/retract).

    Many have asked about using PID for position control, PID is not as well suited for this type of application as simple error correction.

    The attached sample uses the ifm hydraulc library. Specifically the JOYSTICK_1 and CONTROL_OCC blocks.

    Error is calculated from the setpoint and actual position. This error is used as the process variable for the JOYSTICK_1 block. The valve is enageged and as the actual position approaches the setpoint, the valve will slow flow to ramp down the speed of the axis. The error value where the ramping is started is variable so fast and tight control can be achieved. There is also a deadband variable if needed.

    All the control for this example is done in the POSITION_CONTROL POU.

    This can be modified into a function block for reuse. I will try and post a function block in the future.
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