Phrog30
Member
Maybe not what you are after, but check out Pidbot. There is a module for Ignition. You can tune almost anything with it.I'm looking to test out some PID tuning...
https://www.jlbcontrols.com/pidbot
Maybe not what you are after, but check out Pidbot. There is a module for Ignition. You can tune almost anything with it.I'm looking to test out some PID tuning...
I saw you mentioned there was another simulator that you used to prove a deadband was beneficial. Was that written for a PLC also?
drbitboy, I'm just looking for a halfway realistic simulation of a feedback process such as flow, pressure, level or temperature that I can use to compare tuning methods and also check out various auto-tune options to see what works best.
So when the output of the PID goes to 0 the output of the lead/lag filter goes to? This isn't a very good temperature simulator if the temperature goes to 0. It should go to ambient temperature. Also there needs to be an opoen loop gain. Usually the units are degrees/% control output.FOPDT Simulator
So when the output of the PID goes to 0 the output of the lead/lag filter goes to? This isn't a very good temperature simulator if the temperature goes to 0. It should go to ambient temperature. Also there needs to be an opoen loop gain. Usually the units are degrees/% control output.
Add the the bias to the out of the lead/lag block. Add a multiplier on the output of the PID to convert the % control output to temperature.
However, this is just a FOPDT. What about SOPDT? Then insert another lead/lag block in series with the first lead/lag block.
This does cover integrating processes.
Peter- yes, I know the difference. I'm not a wizard at this, but I do it for a living and I'm trying to get better at it. I'm mostly looking for something *resembling* a real life process of any kind so that I can practice various tuning methods and also learn to navigate auto-tune software for situations where that may be useful. I don't have any physical process to practice with, so a software simulation seems like the next best thing. Thanks for the help.These are totally different processes. Flow and temperature are non integrating processes. Level and pressure are integrating processes. The auto tune for integrating process will not work in non-integrating processes.
Velocity is a non-integrating process. Position control is an integrating process.
Do you know the difference?
There are two time constants. There was no cooling system. There is the dead time it take for the thing being heated to get to the temperature sensor. This is a SOPDT system.
The hotrod system was a a soldering, wood or leather burning iron. It was nothing fancy because Ron used a few of these in his training classes.
I didn't see the part about the fan but you are correct about changing the load.I read that thread last night and Ron had a fan blowing on the hotrod, but that was to vary the load, not for controlled cooling.
Yes, the can be many poles, but the dead times are additive when it comes to the final result.Anyway my point was that any system may have several time constants and/or dead times, even if some are so short with respect to others that they may be ignored.
Yes, but there are practical limits. If I could model a system perfectly then I could simply use feed forwards and not worry about closed loop control but reality sucks so closed loop control is necessary. However, My models are usually very accurate and within 2%. This means the feed forwards are correct with 2% and the closed loop control only need to supply at most 2% of the control. This reduces errors significantly.For example, with a jacketed tank the heating/cooling is occurring at a thin layer at the wall of the tank and so will require time* to reach the bulk of the fluid and the temperature sensor. If that time constant is large then the response time of the sensor itself might be negligible and not need to be part of the model, but that doesn't mean it isn't there.
It depends where the poles are. The poles far to the left of the origin is the s-plane can be ignored. In the case of servo hydraulic control I usually ignore the the poles of the valve because they are relatively "fast". If the customer buys a cheap valve where the valve's open loop poles are close to the origin they must accept the poor performance or go through the hassle of setting up an inner loop.So an N-order system (N>2) may be modeled as an (N-K)-order system (N-K<3) without too much loss of accuracy.