Electronic – Confusion in block diagram of open loop and close loop control system

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I am studying Modern Control Systems, 11th edition, by Dorf and Bishop.
On page 221 it first shows in fig4.7 open loop control system(the writer names it as open loop) and on page 222 close loop control system is shown in fig 4.9

Snapshots of both images are attached

I wonder why the writer is calling fig4.7 as open loop despite the fact that it contains feedback path with gain block Kbenter image description here

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Best Answer

This system:

enter image description here

Actually uses the Motor's back EMF as a feedback signal, it does not use the speed information directly.

From a back EMF viewpoint, this is a closed system (the back EMF is directly controlled).

From a motor speed viewpoint, this is an open system (the speed is not directly controlled).

However, this system:

enter image description here

does use the speed of the motor as a feedback signal so the speed is directly controlled.

There is still the back EMF feedback but that does not control the motor speed directly (assuming "sane" choices for \$K_b\$ and \$K_t\$)