PID algorithms and control theory interests me and in my spare time I like to continually read up on articles or revisit textbook material.
As I have read and understand things, the proper way to tune a loop is to collect data about a process' response and obtain tuning parameters based upon data (ie: building a FOPDT model).
However, in pretty much every experience I've had with tuning loops in the industry, I've never actually seen an engineer do this. Usually they have a good idea (based on experience or previous data) of where they want their parameters to be and kind of "play" with the loop to get it to respond within their set tuning criteria. I've seen guidelines out there which give standard ranges of PID parameters based on what kind of process you are trying to control.
So this leads me to some questions on how things should be done realistically; hopefully this isn't just my inexperience in the real world regurgitating things from academia...
Should a process model be derived every time you tune? If not, when is it appropriate, or are there ever instances where it is counter-productive to do so?
Is there ever a point of diminishing returns based on the effort put into trying to tune a loop like this?
Thanks for any input!
As I have read and understand things, the proper way to tune a loop is to collect data about a process' response and obtain tuning parameters based upon data (ie: building a FOPDT model).
However, in pretty much every experience I've had with tuning loops in the industry, I've never actually seen an engineer do this. Usually they have a good idea (based on experience or previous data) of where they want their parameters to be and kind of "play" with the loop to get it to respond within their set tuning criteria. I've seen guidelines out there which give standard ranges of PID parameters based on what kind of process you are trying to control.
So this leads me to some questions on how things should be done realistically; hopefully this isn't just my inexperience in the real world regurgitating things from academia...
Should a process model be derived every time you tune? If not, when is it appropriate, or are there ever instances where it is counter-productive to do so?
Is there ever a point of diminishing returns based on the effort put into trying to tune a loop like this?
Thanks for any input!