Question

Which of the following statements is not necessarily correct for open control system ?

(a) Input command is the sole factor responsible for providing the control action

(b) Presence of non-linearities causes malfunctioning

(c) Less expensive

(d) Generally free from problems of non-linearities

The question was posed to me during an online exam.

This intriguing question originated from Open-Loop Transfer Function in chapter Automatic Control of Machine Dynamics

Answer 1

Right answer is (b) Presence of non-linearities causes malfunctioning

Easy explanation: When the input to a system is independent of the output from the system, then the system is called an open-loop or unmonitored system. It is also called as a calibrated system. Most measuring instruments are open-loop control systems, as for the same input signal, the readings will depend upon things like ambient temperature and pressure.