Power to Win

KB1029 - Understanding and tuning PID controls.


The term PID controller is an acronym for a closed loop system with proportional, integral and derivative modes in its control algorithm. The fact that these three modes exist does not imply that all three modes are necessarily used for any given application.

The purpose of a closed loop control system is to reduce the error between the measurement and the setpoint. The ability of the system to reduce these errors depends on the different controller settings. There are three main modes that contribute to the final output as follows :

Control Modes

Tuning Methods

The quarter amplitude method as described here is one of many used for tuning closed loop control systems. It has proved to be effective in tuning many of the of the functions associated with engine control systems.

  1. Turn the integral and derivative modes off and enable the closed loop control with proportional mode only.
  2. Increment the proportional gain by a quarter of the previous value and monitor the output for oscillations.
  3. Continue until the outputs successive peaks are about one quarter in ampitude of the previous peak.
  4. Enable the integral mode and increment the gain in small steps to eliminate the output error.
  5. Finally enable and add derivative control only if the control loop output needs better performance.


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