In control theory, a controller is a device, historically using mechanical, hydraulic, pneumatic or electronic techniques often in combination, but more recently in the form of a microprocessor or computer, which monitors and physically alters the operating conditions of a given dynamical system.
Consequently, what does a process controller do?
Overseeing the larger production picture, these engineers create and implement new strategies to improve process efficiency, as well as supporting start-up activities. Process control engineers are often responsible for creating or maintaining automation processes, usually in chemical or mechanical industries.
Why PI controller is used?
A proportional–integral–derivative controller (PID controller or three term controller) is a control loop feedback mechanism widely used in industrial control systems and a variety of other applications requiring continuously modulated control.