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PID Autotuning Desgin VI gives NaN for tuned PID values

While autotuning for parameters of PID controllers using Stimulus and Response signals in PID Autotuning Design VI, the values of tuned parameters are either NaN, zero or Inf. How to resolve it

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The function expects you to provide the stimulus as a 'step response' and the response is expected to be a "S" shape or 1st order model. If you try 2nd order, it will not necessarily work and the way the algorithm says that is to give you NaN as PID parameters.

 

The best way to debug is for you to put stimulus response in a graph, convert to controls (it is possible) and then, make current values default to keep the data in the graph. Then, if you post that with a VI trying to calculate the parameters, I can identify what could be wrong...

Barp - Control, Simulation, RTT and HIL - National Instruments
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