Assessment 1
ACT3701
AUTOMATIC CONTROL
Department of Mechanical, Bioresources and Biomedical
Engineering
School of Engineering and the Built Environment
College of Science, Engineering and Technology (CSET)
Primary Lecturer:
H.M. Ngwangwa
Internal Moderator:
V. Ramnath
External Moderator:
R. Tebeta
Weight:
15%
TOTAL MARKS:
30
This assessment is part of Alternative Assessments for the module ACT3701 in
2025. Please comply with the following:
• Save your submitted file strictly in this format:
studentNumber_ACT3701_A1 where “studentNumber” is your unisa
student number. Failure to adhere to this will result in a penalty of 1
marks.
• You will be expected to submit your solutions on the mymodules
Moodle site by 17th April 2025 at 23h00 (SA time). No emailed answer
files are accepted.
• If you have used any software for calculations, remember to include
all your software codes with your submitted answer files.
• All artwork (figures, pictures, and diagrams) must be neat and clear.
• Marks will be lost for incomplete solution procedures, where
important steps are skipped.
• All late submissions will attract a penalty of 1 mark per day from the
assessment submission cut-off date, which is always a day after the
due date.
Assessment 1
Q1.
[30 marks]
Control systems can use a human operator as part of a closed-loop control
system. Sketch the block diagram of the valve control system shown in Figure 1.
[10]
Figure 1. Closed-loop control system with human operator.
Q2.
A system is shown in Figure 2.
10
(a) Find the closed-loop transfer function Y(s)/R(s) when 𝐺𝐺(𝑠𝑠) = 𝑠𝑠2 +2𝑠𝑠+10.
(5)
(b) Determine Y(s) when the input R(s) is a unit step.
(5)
(c) Compute y(t).
(10)
Figure 2. Unity-feedback control system.
[20]
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