Name
Real Time Computing Systems
EE 4770
Final Examination
7 May 1999,
10:0012:00 CDT
Alias
Problem 1
(25 pts)
Problem 2
(25 pts)
Problem 3
(25 pts)
Problem 4
(25 pts)
Exam Total
(100 pts)
Good Luck!
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View Full DocumentProblem 1:
Design a system to convert process variable
x
∈
[0
,
2000 N], force, to a ﬂoating point
number
H
(
x
)=
x/
N, to be written to variable
force
. Force is to be measured using a load cell
with four strain gauges mounted. Force is converted to strain so that
±
=
H
tfs
(
x
±
(
xk
1
+
x
2
k
2
),
where
k
1
=
1
.
100
×
10

7
N
and
k
2
=
2
.
420
×
10

11
N
2
. The sign is based on where the strain gauge is
mounted, two are positive and two are negative. The strain gauges are ideal; their model function
is
H
t
(
±
) = 1000 Ω(1 + 2
±
). (25 pts)
•
Use a 10volt, 16bit ADC.
•
Choose a conditioning circuit appropriate to the strain gauge responses.
•
Show all component and supply values.
•
Write the interface routine. Do not expect a symbolic equation solver to be linked in
with the realtime program.
•
Indicate the minimum precision of
force
. The answer can be given as a formula, be
sure to indicate which values to substitute. Justify your answer.
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 Fall '99
 Staff
 pts, Realtime computing, CPU time

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