Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
EE 518 FINAL EXAM
(120 minutes)
IMPORTANT NOTE: PLEASE READ BEFORE STARTING
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There are five questions, attempt all.
Read the questions carefully.
Show complete work for full credit.
Include units in your answers.
ORGANIZE YOUR WORK AND WRITE LEGIBLY.
GOOD LUCK
Last Name:
First Name:
Student ID:
Signature:
POINTS SCORE
20
Q1
20
Q2
20
Q3
20
Q4
20
Q5
100
TOTAL
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
Q1. (20 pts.)
The block diagram of a simplified model of eye-movement control is
shown below. J represents the moment of inertia of the eyeball about the axis of rotation,
while B represents the viscous damping associated with the rotational movement of the
eye. The target angular position of the eye, ref, is set by the higher centers. G is a gain
that converts the controlling signal into the torque exerted by the extraocular muscles.
Information about the angular position of the eye, , is fed back to the controller with
unity gain. Velocity information is also fed back with variable gain, kv (>0).
Assume that G/J = 14400 rad2s-2, B/J =24 rads- l .
(a) If kv == 0.01, deduce the gain and phase margins of this closed-loop system.
(b) Using the Routh-Hurwitz and Nyquist stability tests, determine the value of kv at
which you might expect the model to exhibit self-sustained oscillations in .
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
(Q1 Continues)
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
Q2(20 pts.) Consider the linear lung mechanics model shown below.
Q
(a) Derive the differential equation governing the time behavior of PA in terms of the
mechanical parameters (R, L and C) and the pressure at the airway opening Pao.
(b) Assume only measurements of PA and Pao are used to identify the three parameters of
the linear lung mechanics model. Comment on the success of this approach.
(c) Assume an alternative approach that uses the measurements of Pao and Q to identify
the linear lung mechanics model. Derive necessary equations and show whether the
system is identifable with this approach.
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
(Q2 Continues)
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
Q3(20 pts.) Assume that the block diagram of a temperature-regulating space-suit to
be worn by an astronaut for a mission to Mars is as shown below. The variable x
represents the external temperature while y represents the temperature inside the spacesuit. Gc is the steady-state gain of the heating/cooling device (controller) built into the
space-suit, while Gp represents the steady state gain associated with the thermal
characteristics of the astronaut. H is the gain with which the internal temperature is fed
back to the controller. The operating internal temperature (y) is allowed to range from
60°F to 100°F. Assume that Gc = 2, Gp = 1, and H = 7.
(a) What range of external temperatures can this space-suit be used for, if it is deployed
in open-loop mode?
(b) What is the permissible range of external temperatures when the space-suit is
deployed in closed-loop mode?
(c) Based on the results obtained in (a) and (b), what can you conclude about the effect of
negative feedback in this device?
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
(Q3 Continues)
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
Q4(20 pts.)
Fluctuations in the heart rate reflect beat-to-beat modulation of
sympathetic and parasympathetic tone. The frequency specific effects of sympathetic
and parasympathetic modulation on spontaneous heart rate variability can be explained
on the basis of the response properties of the SA node. Consider the folowing linear
system model of the SA.
To identify the atrial rate response to fluctuations imposed in vagal tone, experiments
were performed using animals. All endogenous neural influences were interrupted. To
excite the system under study with a broad-band input signal, a train of 2 ms wide
current pulses (typically 2 mA) were applied. The frequency of current pulses was
varied about some mean rate in proportion to a Gaussian white-noise signal. The
results are shown in the following figures.
Analyze the results and list your comments about the frequency response of the
system providing reasonable explanations.
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
(Q4 continues)
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
Q5( 20 pts.) Answer the following questions.
(a) (2 pts.) Explain major differences between engineering and physiological control
systems:
a.
b.
c.
d.
(b) (2pts.) Explain two
fundemantal approaches employed
mathematical model for a physiological control system.
a.
to develop a
b.
(c) (1 pt.) The use of feedback
makes the system response relatively
............................... to external disturbances and internal variations in system
properties.
(d) (2 pts.) ................ ................ sends afferent neural impulses back to spinal cord in
proportion to the length of the muscle, so the afferent traffic ....................... when the
muscle is stretched.
(e) (2 pts.) ...................... are short vessels composed almost exclusively of smooth
muscle. They serve as "stopcocks" or valves that regulate the flow of blood from
arteries to capillary beds. The ....................... are short, thin-walled vessels that
provide a large total cross-sectional area (considering all capillaries as a unit) for
exchange of materials with interstitial fluid and cells.
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Spring 2010/2011
EE 518 Physiological Control System Analysis
June 6th, 2011
(f) (2 pts.) Cardiac output is determined by two factors:
a.
b.
(g) (2 pts.) The main defect in Type-1 diabet is the .................... of the islet cells in
the pancreas to produce sufficient ................ .
(h) (2 pts.) The ventilatory control system is divided intio two components:
a.
b.
(i) (2 pt.) Explain the use and implementation of Nichols Charts.
(j) (2 pts.) The overall affect of ........................... ......................., commonly referred
as the respiratory sinus arrhythmia, can be quantified in terms of a ........................
.................................... .
(k) (1 pts.) A rise in the arterial pressure produces a ........................... in the
sympathetic activity and an ……………… in the parasympathetic activity.
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