LOOP-PRO stands apart in terms of the data that can be used to successfully tune PID control loops. Like other tuning packages LOOP-PRO needs data the contains information specific to the control loop, including the Process Variable, Controller Output as well as the corresponding Time Stamp. Relative to other tools that’s where the similarities stop. Unlike other tuning packages LOOP-PRO can accurately model complex processes using data that is both noisy and oscillatory. That’s real-world data. That’s the LOOP-PRO difference.
The process data requirements for tuning software are based on some general rules of thumb. When tuning PIDs it’s helpful to keep the following guidelines in mind:
- DLO: Data should be collected around the Design Level of Operation (DLO) to assure that tuning parameters are best suited for a loop’s normal range of operation
- Sample Rate: Data should be collected at speeds fast enough to reveal the loop’s true dynamics and to avoid aliasing. Data that is at least five (5) times the process Time Constant or three (3) times faster than the process Dead Time are good rules of thumb.
- Noise Band: Step test data should force the Process Variable outside any associated noise in the process. A rule of thumb is to perform tests that are at least four (4) times the noise band.
Fortunately LOOP-PRO has built-in heuristics that alert users when the process data has limitations. The following offer additional insight into LOOP-PRO’s capabilities.