Controlling water level of spherical tank using labview.

[Control]

Hi, I'm trying to control the water level of a spherical tank model using PID in labview. The model is a non-linear equation as follows:
Qi(t-L)-Qo=pi*R^2(1-(R-y)^2/R^2)dy/dt
where Qi=inlet flow
Qo=Outlet flow
R=tank radius
y=height of water
t=time
In order to get y, i have shifted the right hand side to the left and integrating it. However, i can't implement the integration of this non-linear equation in labview. Pls advise. Thank you.
Attached are the files that i've tried.

[CraigGraham]

I've never seen this approach before and don't really know what you're doing
from this snippet.

What you essentially have is a system where the proportionality term varies
depending on the current height of the water. This isn't too different from
heater controls where the heater can operate anywhere between 70 and 450K.
What we do here is to simply have a table of a handful of PID values
appropriate to a range of levels and simply linearly interpolate between
them to obtain an approximate value appropriate to the current level.

Control wrote in message
news:506500000008000000A72D0000-1002247793000@exchange.ni.com...
> Hi, I'm trying to control the water level of a spherical tank model
> using PID in labview. The model is a non-linear equation a
s follows:
> Qi(t-L)-Qo=pi*R^2(1-(R-y)^2/R^2)dy/dt
> where Qi=inlet flow
> Qo=Outlet flow
> R=tank radius
> y=height of water
> t=time
> In order to get y, i have shifted the right hand side to the left and
> integrating it. However, i can't implement the integration of this
> non-linear equation in labview. Pls advise. Thank you.
> Attached are the files that i've tried.

[chromepet]

hi,

 i have obtained the open loop response of spherical tank level control using labview. i need to know the appropriate tuning parameter values for pid controller to implement closed loop spherical tank level control with level as set point.pls give me value for the tuning parameters such as k,ti,td.

[_Bryan]

You would be better off starting a new thread, the thread you replied to is 9 years old.

Appropriate values for your PID are going to depend on the equipment you are using.  There is not a set of magic numbers that will work in all situations, that I know of.  That is just part of the tuning process.  As long as nothing can get damaged just start with some numbers and see how they system controls.  If you do not like the way it controls change a value and try again.

Do a search for PID tuning and see what you can come up with.  Different people will use different methods for tuning.

[bingi]

hi

 how u conduct open loop response in LABVIEW 

  can u send those files

  plz