Overview of PID Tuning

The PID algorithm is a control algorithm based on position error. PID is a very common control algorithm in the motion control industry. It is used in a variety of systems ranging from precise motion control to fluid level control to temperature control.

The two major methods of tuning the PID loop that will be discussed in this overview are: Trial-based iterative methods and frequency shaping.

Trial-based Iterative Methods

Trial-based iterative methods include:
         - Step Behavior / Overshoot criteria
         - Step Behavior / Stability Criteria
         - Under Damped / Over Damped

Trial-based iterative methods require some sort of move to be made. The response of the system is observed in the time domain and an adjustment towards the goal is made based on the response of the system. This is iterated until you are satisfied with the results. One of the attractive features of trial-based iterative methods is that it is easy to command a move and get the time domain response of the system.

NOTE: MEI's Motion Scope is a tool that is used for getting the time domain response of the system.

Overview of Frequency Shaping Tuning

Frequency shaping methods require that the response of the system in the frequency domain is acquired. Once the frequency response of the system is known, possible control algorithms can then be evaluated. PID is one of many control algorithms that this method supports. Frequency shaping methods not only require that an accurate response of the system and the control algorithm are available, but also that the combined response is available.

NOTE: MEI's Bode Tool is a tool for performing such simulation.

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