10-26-2020 09:11 PM
Hi all,
I am new with PID but have foundational knowledge.I want to create a system where the user sets desired flow rate (GPM) and then the pump automatically adjusts itself to reach that flow rate. Is it appropriate to use PID control?
The process variable is a flow sensor (reading the flow rate in GPM). The water pump is controlled using a variable voltage DC power supply with a range of 0-24 V. The range in flow rate is about 0-3 GPM. The measurements are read by a NetDAQ unit.
Should I start with looking at the Labview General PID example and then change the variables, i.e. pv = flow sensor (gpm), sp= user defined (gpm) , pid output = water pump (voltage)?
I have looked over the Labview General PID.vi simulator with the plant but confused on how to figure out the PID gains where the pump slowly increases or decreases to the set point value, i.e. in increments of 0.1 GPM.
10-27-2020 02:24 AM
Hi code,
@Code44 wrote:
I have looked over the Labview General PID.vi simulator with the plant but confused on how to figure out the PID gains where the pump slowly increases or decreases to the set point value, i.e. in increments of 0.1 GPM.
Have you learned about Ziegler and Nichols?
They explained how to determine PID gains…
10-27-2020 02:48 AM - edited 10-27-2020 02:49 AM
@GerdW
I have not. Is there a LabVIEW white paper, resource, or toolkit on this?
10-27-2020 04:03 AM
Hi Code,
@Code44 wrote:
I have not. Is there a LabVIEW white paper, resource, or toolkit on this?
This is basic (PID) control theory stuff: you can read about that in each good book on this matter!
I already provided the Wikipedia link, what else do you need to search for information on your own?
LabVIEW provides a PID-Tuning function, but I didn't use it so far to get good PID gains. I always follow the Ziegler-Nichols rules to determine them…
10-27-2020 10:10 AM
Is PID a good solution? Yes.
Is it hard to get the right control values? Yes.
Is Z-N a decent (if somewhat aggressive) way of finding these values? Yes. 🙂