FACULTY OF ENGINEERING

CINEC

COURSE : Bsc Part time Batch 07

SUBJECT : 6ET006 Control Engineering I

ASSESSMENT : Tutorial 1

DATE : 4th

June 2015

DUE DATE :

1

1.1 Redesign the turbine speed control system discussed in the class, but

replace the fly-ball governor with the tachometer shown in Fig. P1.2. A

tachometer consists basically of a small DC motor operated in reverse as

a generator, the shaft being rotated continuously , producing a DC voltage

proportional to shaft speed.

1.2 The system in Fig. P1.3 shows an operator attempting to maintain the

speed of a conveyor carrying manufactured parts through a spray

booth. When more boxes are placed on the conveyor, it slows down,

while fewer boxes allow it to speed up. Draw a block diagram of the

system indicating the principal elements and transfer functions where

possible.

1.3 Shown in Fig. P1.4 is a water-level control system comprising a tank,

inlet pipe, slide valve, and float. Details of the operation of the flow valve

are also shown in the figure. Draw a block diagram of the feedback

control system and identify the main elements, writing down the

mathematical transfer functions where appropriate.

2

1.4 Consider Fig. P1.6. which shows a stick balanced on top of a cart that

is free to move horizontally. The angle of the stick with the vertical is

measured by means of a potentiometer. Using components discussed

so far, specify a control system that will move the cart so as to

maintain the stick in the upright position when disturbed. Draw the

block diagram of the system and identify the major elements. Can the

system be used to maintain the stick at a constant, nonzero angle to the

vertical'?

3

1.5 Figure P1.7 shows a beam with a V groove cut into it and a steel

ball that is free to roll in the groove. Along one face of the groove is

a carbon track of fixed resistance. A 10-V supply is connected to

one end of one track while the other end is grounded. The ball

connects the energized track to a wire on the other face of the V,

which assumes a voltage proportional to the position of the ball x

from the grounded end, the whole system working as a linear

potentiometer. The beam is free to rotate about its center and is

actuated by a geared motor at one end that moves a lead screw with

velocity proportional to input voltage. Design and draw a labeled

block diagram of a control system capable of positioning the ball

anywhere on the beam.

1.6 The automatically guided vehicle shown in Fig. P1.8a follows a white

line painted on a factory flow by means of the system shown in Fig.

P1.8b. The line is illuminated with a lamp and the reflected light is

measured by a photo detector. As the vehicle wonders off the track, the

photo detector signal decreaes due to the decrease in the white- line area

beneath it, as shown by the dashed line in Fig.P1.8b.Design a control

system to ensure accurate tracking , and draw a block diagram of the

pricipal elements.

4

1.7 Design a control system that will maintain the depth of a submarine at a

prespecified value. The drive planes are actuated by means of the

arrangement shown in Fig. P1.9. A pressure sensor signal is available that

delivers a voltage propotional to water pressure, with a known calibration

coeffient. Design a system that uses this voltage to drive the submarine to

a preset depth and describe its operation.

1.8 A control system has to be designed to maintain the thickness of a steel

plate as it is hot rolled, as shown in Fig. P1.10. The thickness is measured

by a roller mounted on a swinging arm connected to and pivoting about a

potentionmeter and fed back to the control room where it may be

compared to the thickness dialed by the operator on an identical

potentiometer. The top rollar is adjusted in height by means of the

hydraulic ram shown in the figure. Complete the design indicating all

elements of the control system by a transfer function where possible.