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Cyclider Position Control

Dear Experts, 

We have following requirement in our project. 

There are some cylinders to control the choke of a machinery. 

We have two DO signals in DCS to open and Close. One AI signal for Position indication. 

From the operator Display they need two Buttons OPEN  and CLOSE. One Analog indicator to indicate the position. 

From the Display, If operator Keep Pressing the OPEN button then the Cylinder should open continuously. He can see the position indication in the AI indicator. 

If he releases the OPEN button then it should hold  in the same position. 

Likewise if he keep pressing the CLOSE button then the Cylinder to close  from the position where it got hold. 

I have searched in PCSD for this application , I could not find any. 

If anybody has used this application please share with me.

Thanks,

Manik

manik

21 Replies

  • gamella
    Using mouse in this way can bé hard to implement and to use for operator.

    I propose a different three buttons based approach:
    1-stop
    2-close
    3-open

    Then you can use a DC block, with active2 enabled, to manage both outputs. Named sets for stop/close/open must bé defined and used with DC.

    As both, close and open activate a DO it makes sense to consider both as active states.

    The module then will work like a 2 speed o a fordwad/reverse motor module.

    To operate, click close, or open, until desired position and then click close.

    Regards
     
    De: manik [mailto:[email protected]]
    Enviado: Monday, September 15, 2014 09:42 PM
    Para: [email protected] <[email protected]>
    Asunto: [EE365 DeltaV Track] Cyclider Position Control
     

    Dear Experts, 

    We have following requirement in our project. 

    There are some cylinders to control the choke of a machinery. 

    We have two DO signals in DCS to open and Close. One AI signal for Position indication. 

    From the operator Display they need two Buttons OPEN  and CLOSE. One Analog indicator to indicate the position. 

    From the Display, If operator Keep Pressing the OPEN button then the Cylinder should open continuously. He can see the position indication in the AI indicator. 

    If he releases the OPEN button then it should hold  in the same position. 

    Likewise if he keep pressing the CLOSE button then the Cylinder to close  from the position where it got hold. 

    I have searched in PCSD for this application , I could not find any. 

    If anybody has used this application please share with me.

    Thanks,

    Manik

  • gamella
    Good point!!!
     
    De: amodbobade [mailto:[email protected]]
    Enviado: Wednesday, September 17, 2014 12:38 PM
    Para: [email protected] <[email protected]>
    Asunto: RE: [EE365 DeltaV Track] Cyclider Position Control
     

    Just out of academic curiocity..... What if one operator on one HMI keeps OPEN button pressed, while the other operator on another HMI keeps CLOSE button pressed??

  • SBPosey
    Since you get position as a feedback indication, my first thought was something like this (if hold for open/hold for close is not a hard requirement):

    Where the operator would provide a position setpoint. The CALC has 3 outputs. OUT1 is a request to open (0/1) if the SP > PV by some margin (you may not be able to control finely enough to achieve PV exactly). OUT2 is a request to close (0/1) if the SP < PV by some margin. OUT3 is the absolute value of the difference between SP and PV. The SGCR converts the SP-PV difference to a pulse duration. The higher the difference, the longer the pulse.
    Say the valve is 70% open and the SP is changed to 20% open. Let's say the valve can move at 1% per sec and the module has a scan time of 1 sec.
    The logic would pulse the CLOSE output for 30 sec, then de-energize for 1 scan. Valve is now 40% open.
    The logic would pulse the CLOSE output for 15 sec, then de-energize for 1 scan. Valve is now 25% open.
    The logic would pulse the CLOSE output for 4 sec, then de-energize for 1 scan. Valve is now 21% open.
    The logic would either pulse the CLOSE output for 1 sec to get to 20% open or leave it at 21% depending on the margin in the Calc.
    Choose X and Y values for the SGCR block based on scale of the PV (is it in % or inches or something else?) and the speed of the valve.
    The idea is to not overshoot (don't want to hunt for SP by continuously opening and closing), set and forget for the operator, control lives in the controller, not the HMI.




    From:        "David Nelson" <[email protected]>
    To:        <[email protected]>,
    Date:        09/17/2014 10:31 AM
    Subject:        RE: [EE365 DeltaV Track] Cyclider Position Control



    Look at www2.emersonprocess.com/.../Interactive.aspx in the DeltaV application exchange.  This is an example of how to use motorized actuators for PID control.  Something similair could be done with this.  Instead of the operator holding an open or close button until they get the choke in the desired position, they could just give a setpoint for the choke postion and let the PID-type module take over.  I had a previous co-worker setup similar type control using a MOV on a steam line and it worked pretty well.

  • SBPosey
    I didn't see my first attempt at sending this message show up; here is my second attempt.

    Since you get position as a feedback indication, my first thought was something like this (if hold for open/hold for close is not a hard requirement):

    Where the operator would provide a position setpoint. The CALC has 3 outputs. OUT1 is a request to open (0/1) if the SP > PV by some margin (you may not be able to control finely enough to achieve PV exactly). OUT2 is a request to close (0/1) if the SP < PV by some margin. OUT3 is the absolute value of the difference between SP and PV. The SGCR converts the SP-PV difference to a pulse duration. The higher the difference, the longer the pulse.
    Say the valve is 70% open and the SP is changed to 20% open. Let's say the valve can move at 1% per sec and the module has a scan time of 1 sec.
    The logic would pulse the CLOSE output for 30 sec, then de-energize for 1 scan. Valve is now 40% open.
    The logic would pulse the CLOSE output for 15 sec, then de-energize for 1 scan. Valve is now 25% open.
    The logic would pulse the CLOSE output for 4 sec, then de-energize for 1 scan. Valve is now 21% open.
    The logic would either pulse the CLOSE output for 1 sec to get to 20% open or leave it at 21% depending on the margin in the Calc.
    Choose X and Y values for the SGCR block based on scale of the PV (is it in % or inches or something else?) and the speed of the valve.
    The idea is to not overshoot (don't want to hunt for SP by continuously opening and closing), set and forget for the operator, control lives in the controller, not the HMI.



    From:        "David Nelson" <[email protected]>
    To:        <[email protected]>,
    Date:        09/17/2014 10:31 AM
    Subject:        RE: [EE365 DeltaV Track] Cyclider Position Control



    Look at www2.emersonprocess.com/.../Interactive.aspx in the DeltaV application exchange.  This is an example of how to use motorized actuators for PID control.  Something similair could be done with this.  Instead of the operator holding an open or close button until they get the choke in the desired position, they could just give a setpoint for the choke postion and let the PID-type module take over.  I had a previous co-worker setup similar type control using a MOV on a steam line and it worked pretty well.

  • SBPosey
    I see that my posts were approved and posted, but without the image that made the post intelligible. Oh well, next time, I'll guess I'll stick to ASCII art images.



    From:        "SBPosey" <[email protected]>
    To:        <[email protected]>,
    Date:        09/19/2014 10:24 AM
    Subject:        RE: [EE365 DeltaV Track] Cyclider Position Control



    I didn't see my first attempt at sending this message show up; here is my second attempt.

    Since you get position as a feedback indication, my first thought was something like this (if hold for open/hold for close is not a hard requirement):

    Where the operator would provide a position setpoint. The CALC has 3 outputs. OUT1 is a request to open (0/1) if the SP > PV by some margin (you may not be able to control finely enough to achieve PV exactly). OUT2 is a request to close (0/1) if the SP < PV by some margin. OUT3 is the absolute value of the difference between SP and PV. The SGCR converts the SP-PV difference to a pulse duration. The higher the difference, the longer the pulse.
    Say the valve is 70% open and the SP is changed to 20% open. Let's say the valve can move at 1% per sec and the module has a scan time of 1 sec.
    The logic would pulse the CLOSE output for 30 sec, then de-energize for 1 scan. Valve is now 40% open.
    The logic would pulse the CLOSE output for 15 sec, then de-energize for 1 scan. Valve is now 25% open.
    The logic would pulse the CLOSE output for 4 sec, then de-energize for 1 scan. Valve is now 21% open.
    The logic would either pulse the CLOSE output for 1 sec to get to 20% open or leave it at 21% depending on the margin in the Calc.
    Choose X and Y values for the SGCR block based on scale of the PV (is it in % or inches or something else?) and the speed of the valve.
    The idea is to not overshoot (don't want to hunt for SP by continuously opening and closing), set and forget for the operator, control lives in the controller, not the HMI.



    [collapse] From:            "David Nelson" <[email protected]>
    To:            <[email protected]>,
    Date:            09/17/2014 10:31 AM
    Subject:            RE: [EE365 DeltaV Track] Cyclider Position Control



    Look at     www2.emersonprocess.com/.../Interactive.aspx in the DeltaV application exchange.  This is an example of how to use motorized actuators for PID control.  Something similair could be done with this.  Instead of the operator holding an open or close button until they get the choke in the desired position, they could just give a setpoint for the choke postion and let the PID-type module take over.  I had a previous co-worker setup similar type control using a MOV on a steam line and it worked pretty well.

    [/collapse]

  • Rachelle McWright

    In reply to SBPosey:

    Hello,

    We sincerely apologize for the inconvenience. We are working through some technical issues with our platform provider regarding comments made by replying by email--that are being stuck in a delayed filter without cause. Until resolved, we suggest posting directly from the site to the forum. Will keep you updated on this issue, thanks for your patience. :)

    Best Regards,

    Rachelle McWright: Business Development Manager, Dynamic Simulation: U.S. Gulf Coast

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