A proportional-integral-derivative controller (PID controller) is a generic control loop feedback mechanism widely used in industrial control systems. A PID controller calculates an “error” value as the difference between a measured process variable and a desired setpoint. The controller attempts to minimize the error by adjusting the process control inputs.
In coffee maker industry the PID improves the brewing precision, by allowing the brewing temperature to be maintained between certain parameters.
The PID of an espresso machine controls various heating elements of the unit. The PID controlled element can heat the brewing boiler, the milk steaming boiler, or with some high end machines, the brew head. The PID increases the temperature in calculated increments in order to reach a set temperature as called Set Value (SV).