I recently had a query along the lines of:

Our controller has a table of P, I and D gains that our controller uses in different [load] conditions. Will your tuning methods work with this kind of setup?

The short answer is: Yes, you could do an open loop test for each set of conditions and put the different PID values in your table.

But…

Changing the PID parameters to suit changing loads or disturbances is known as “Gain Scheduling”. In my experience 99% of gain scheduling applications are merely band aid for crappy Trial and Error Tuning.

I find that using a scientific, open loop, tuning method will usually leave you with a loop that can cope with a very wide variety of changing conditions, meaning the complex gain scheduler can be dumped.

Has anyone got a process that they think wouldn’t work without Gain Scheduling? Let me know, we’ll try to tune it with the PID Tuning Blueprint and see if afterwards the gain scheduler can’t be thrown in the bin!