Which statement is FALSE about open loop

Solution

An open loop control system is one where the output is not measured or fed back to the input. The control action depends only on the input signal. These systems are simple, economical, and easy to design , but they are less accurate and less reliable because they cannot correct any error caused by disturbances or parameter variations. Example: an electric toaster, where heating time is fixed regardless of actual toast color. On the other hand, a closed loop control system uses feedback. The output is continuously monitored and compared with the input (reference), and any error is fed back to correct the system’s action. This makes closed loop systems more accurate, reliable, and stable , but they are more complex and expensive than open loop systems. Example: automatic temperature control in an air conditioner, where the output (room temperature) is fed back to control the compressor. Therefore, the false statement is: “An open loop uses unity feedback system”, because open loop systems by definition do not have any feedback path at all.