Question $1$

$[20$ marks$]$

For young children, the capability of controlling the hands is trained via tracing

lines using a pen, as shown in Fig. Q$1.$The predefined line is the desired path that

a child aims to trace by controlling the pen. The child focuses on the actual

trajectory of the pen. When the pen goes out of the predefined line, the child awares

of the distance via eyes, then the brain interpret the distance to a decision on where

the pen goes at the next moment. This decision is used to control the muscle of the

hand and fingers to control the pen moving towards the predefined line.

Fig Q$1$

This is a dynamic process that the pen is continuously controlled to trace the line.

For this process:

$1\mathrm{.}1$ List the components involved in the closed loop control system.

$1\mathrm{.}2$ List the signals$/$variables involved in the closed loop control system. $(5)$

$1\mathrm{.}3$ Draw a block diagram containing all the components and signals listed above

to demonstrate how the closed loop control system works.