Transcript Design for Engineering Unit 4 Instrumentation and Control

Design for Engineering
Unit 4 Instrumentation and Control Systems
Annette Beattie
June 9, 2006
Instrumentation and Control Systems
ETP 2006 – Annette Beattie
This material is based upon work supported by the National
Science Foundation under Grant No. 0402616. Any opinions,
findings and conclusions or recommendations expressed in
this material are those of the author(s) and do not necessarily
reflect the view of the National Science Foundation (NSF).
Engineering
The engineering profession is based
upon mathematics and data.
 Design decisions and changes are
ALWAYS based upon data that has
been gathered.
 Data is gathered through
instrumentation and control
systems.

Instrumentation and Control Systems
Instrumentation - the act of using
instruments for a particular purpose
 Ex. - instrumentation on a car
dashboard - speedometer, odometer,
oil gauge, temperature, etc.


(ITEA/CATTS, 2003)
Instrumentation and Control Systems
Control - to keep within limits or to
have power over
 System - a means of achieving a
desired result. It has:

 Input
 Process
 Output
 Feedback

(ITEA/CATTS, 2003)
Instrumentation and Control Systems

System example - Car
 Input
- driver puts it in drive, pressure on the
pedal
 Process - transmission is activated, gas is
sent to engine
 Output - car is ready to move forward, car
moves according to pressure on pedal
 Feedback - PRND12 - the D is highlighted,
the speedometer gives speed read out. We
also receive feedback from warning lights on
the dash to tell us if something is wrong with
the car or if we need fuel.
Instrumentation and Control Systems
Control system - a system for
controlling the operation of another
system (dictionary.net, n.d.)
 Example - the dashboard in your car
 Example - the stereo in your car

 What
is the control system?
 What is the system it’s controlling?
 What is the instrumentation?
Closed-Loop Control

One that involves feedback to ensure set
conditions are met (school-resources.co, n.d.)
 Example - you turn on the radio,

pick a station (input),
 listen to the song (process),
 you don’t care for it (feedback),
 and decide to change stations (output)
 the loop continues picking another station until
the feedback says to stay on that station. Or
everyone else in the car is yelling at you, which
is another kind of feedback.
Open-Loop Control

The system of commands are carried
out regardless of the consequences.
(school-resources.co, n.d.)

Example - Sprinklers for a golf course
programmed to come on at 6:00 am
even if it’s raining.
Binary

The binary number system (aka base 2)
represents values using two symbols,
typically 0 and 1. Computers call these bits.
 A bit is either off (0) or on (1).
 When arranged in sets of 8 bits (or 2 bytes)
256 values can be represented (0-255).
 Using an ASCII chart, these values can be
mapped to characters and text can be
stored. It's not magic, it's just math! (Ciske,
n.d.)
Binary

Example - the word “Tech Ed” is
written in binary code as:
0101010001100101011000110110100
0001000000100010101100100 (Ciske,
n.d.)
Digital
Conversion of information into binary
bits of data for transmission through
wire, fiber optic cable, satellite, or over
air techniques. Method allows
simultaneous transmission of voice,
data or video. (Remote Satellite Communications, 2006)
 Examples - a computer, a digital clock

Analog

Also spelled analogue, describes a device
or system that represents changing values
as continuously variable physical quantities.
 A typical analog device is a clock in which
the hands move continuously around the
face. Such a clock is capable of indicating
every possible time of day. In contrast, a
digital clock is capable of representing only
a finite number of times (every tenth of a
second, for example). (webopedia.com, n.d.)
Analog vs. Digital
In general, humans experience the
world analogically. Vision, for example,
is an analog experience because we
perceive infinitely smooth gradations of
shapes and colors.
 Computers are digital machines
because at their most basic level they
can distinguish between just two
values, 0 and 1, or off and on.

(webopedia.com, n.d.)
Analog vs. Digital
A converter is used to change analog
information into digital information that
a computer can understand.
 In turn, a different converter is used to
convert digital information put out by a
computer into analog data.

Microprocessor


A microprocessor -also known as a CPU
or central processing
unit -- is a complete
computation engine
that is fabricated on a
single chip.
This is the first
microprocessor ever
invented - the Intel
4004. (Howstuffworks.com,
n.d.)
Microprocessors

The first PC
microprocessor
was the Intel 8080.
It had 6000
transistors.

Today’s processor
for PC’s is the
Pentium 4. It has
42 million
transistors.
(Howstuffworks.com, 2000)
Fuzzy Logic

A problem-solving control system method
 It provides a simple way to arrive at a
definite conclusion based upon vague,
ambiguous, imprecise, noisy, or missing
input information.
 It mimics how a person would make
decisions, only much faster. (Seattle Robotics
Society, n.d.)

Deals with reason that is approximate
instead of precise. (wikipedia.org, n.d.)
Fuzzy Logic

For example, rather than dealing with
temperature control in terms such as
"SP
=500F” and "T <1000F", terms like "IF
(process is too cool) AND (process is getting
colder) THEN (add heat to the process)" or
"IF (process is too hot) AND (process is
heating rapidly) THEN (cool the process
quickly)" are used.
 These terms are imprecise and yet very
descriptive of what must actually happen.
Similar to how you would think and react in
the shower if the temperature changed.
(Seattle Robotics Society, n.d.)
Fuzzy Logic

Fuzzy truth represents membership in
vaguely defined sets, not likelihood of
some event or condition. To illustrate
the difference, consider this scenario:
Bob is in a house with two adjacent
rooms: the kitchen and the dining
room. In many cases, Bob's status is
"in the kitchen" which is completely
plain: he's either "in the kitchen" or
"not in the kitchen". (wikipedia.org, n.d.)
Fuzzy Logic

What about when Bob stands in the
doorway? He may be considered "partially
in the kitchen". Quantifying this partial state
yields a fuzzy set membership. With only his
little toe in the dining room, we might say
Bob is 99% "in the kitchen" and 1% "in the
dining room", for instance. No event (like a
coin toss) will resolve Bob to being
completely "in the kitchen" or "not in the
kitchen", as long as he's standing in that
doorway. Reasoning that is approximate
rather than precisely deduced. (wikipedia.org, n.d.)
Fuzzy Logic

Fuzzy logic allows for values between and
including 0 and 1, shades of gray as well as
black and white.
 Fuzzy logic is used in air conditioners,
dishwashers, elevators, video games, etc.
 It was also used to create MASSIVE
(Multiple Agent Simulation System in Virtual
Environment). It is computer animation and
artificial intelligence software that was
developed for the Lord of the Rings trilogy.
(wikipedia.org, n.d.)
Fuzzy Logic

Fuzzy logic
software was used
to create award
winning visual
affects, particularly
the battle scenes of
Lord of the Rings.
 The software was
also used in The
Lion, the Witch, and
the Wardrobe.
(wikipedia.org, n.d.)
Neural Systems

A type of artificial intelligence that attempts
to imitate how a human brain works.
 Rather than using a digital model, in which
all computations manipulate 0’s and 1’s, a
neural network works by creating
connections between processing elements,
as if computer neurons.
 The organization and weights of the
connections determine the output.
(Pcwebopidia.com, n.d.)
Neural Systems
Neural network systems are
particularly effective for predicting
events when the networks have a
large database of prior examples to
draw on.
 Strictly speaking, a neural network
system implies a non-digital computer,
but neural network systems can be
simulated on digital computers.

(Pcwebopidia.com, n.d.)
Neural Systems

Neural networks
are currently used
prominently in voice
recognition
systems, image
recognition
systems, industrial
robotics, medical
imaging, and
aerospace
applications.
(Pcwebopidia.com, n.d.)
Sensors
A device that responds to a stimulus,
such as heat, light, or pressure, and
generates a signal that can be
measured or interpreted. (St. Jude, 2006)
 A significant change involves an
exchange of energy, so sensors can
be classified according to the type of
energy transfer they detect. (Wikipedia.org,

n.d.)
Sensor Examples

Thermal sensors
 Thermometers,
thermostats,
thermocouples

Electromagnetic sensors
 Ohmmeter,

Mechanical sensors
 Altimeter,

voltmeter, metal detectors
pressure gauge
Motion sensors
 Radar
gun, speedometer, odometer
(Wikipedia.org, n.d.)
Actuator
A mechanism that puts something into
automatic action.
 Examples 
 A mail
delivery system that delivers email
into the user’s mailbox
 A human - moving arms, legs, fingers
 A robot - that grasps parts and moves
them
 Motors - used when circular motions are
needed or a rack and pinion is used in
conjunction to make a linear motion
(Howstuffworks.com, 2000)
Actuator example

A model of an
actuator (IX SCARA
Applications, n.d.)

http://www.intelligen
tactuator.com/medi
a/m-ap-ix0001_01.swf
Actuator example

Actuator used to open power door locks
 The hook at the end of the actuator rod
moves up or down which mimics a person
moving the knob up or down. (Howstuffworks.com,
2000)
Actuator example

Inside of the actuator
 The small electric motor turns the gears
which move the rack and pinion which
moves the actuator rod up or down.
(Howstuffworks.com, 2000)
Stepper Motor

These are small
electric motors that can
spin quite quickly and
can be started and
stopped “on a dime”.
Instead of moving
continuously, they
move is small, precise
increments.
 Stepper motors are
used to spin floppy
disks.
 They are also used to
move an ink jet printer
head assembly back
and forth.
(Howstuffworks.com, 2000)
Synchro Motor

A system consisting of a generator and
a motor so connected that the motor
will assume the same relative position
as the generator; the generator and
the motor are synchronized
(Thefreedictionary.com, n.d.)

A synchro motor resembles a small
electric motor in size and appearance
and operates like a variable
transformer.
Synchro Motor

Synchros are used
primarily for the
rapid and accurate
transmission of
data.
 They are used to
move small dials to
give read-outs.
(Concord University, n.d.)
Putting it all together
Most manufactured cars today have
around 50 microprocessors.
 The following is a picture of the most
important computer in a car which
uses many microprocessors - the
engine control unit (ECU).

(Howstuffworks.com, 2000)
Putting it all together
Putting it all together


It gathers data from many different sensors
It uses closed-loop control to monitor the
outputs of a system to control the new
inputs of that system.
 It knows everything about:



Coolant temperature
Amount of oxygen in the exhaust, etc.
With this information it performs millions of
calculations each second.
 This determines the best spark timing and
how long the fuel injector is open, for
instance. (Howstuffworks.com, 2000)
Putting it all together

The pins on this ECU’s connector interface
with sensors and control systems all over
the car. (Howstuffworks.com, 2000)
Other components in the ECU are:

An analog-to-digital converter is
used to read the outputs of some of
the sensors in the car, such as the
oxygen sensor. The output of an
oxygen sensor is an analog voltage,
usually between 0 and 1.1 volts (V).
The processor only understands
digital numbers, so the analog-todigital converter changes this voltage
into a 10-bit digital number.
(Howstuffworks.com, 2000)
Other components in the ECU are:

Digital-to-analog converters Sometimes the ECU has to provide an
analog voltage output to drive some
engine components. Since the
processor on the ECU is a digital
device( a computer), it needs a
component that can convert the digital
number into an analog voltage.
(Howstuffworks.com, 2000)
Sources













Ciske. (n.d.). Retrieved June 9, 2006 from the website: Nickciske.com
Concord University (n.d.). Retrieved June 9, 2006 from the website:
students.concord. edu
Dictionary.net. (n.d.). Retrieved June 9, 2006 from the website:
http://www.dictionary.net/control+system
Howstuffworks.com. (2000). Retrieved June 9, 2006 from the website:
Howstuffworks.com
ITEA/CATTS. (2003). Introduction to engineering: units of instruction. Retrieved
June 9, 2006 from the website: http://www.vcsu.edu
IX SCARA Applications. (n.d.). Retrieved June 9, 2006 from the website:
intelligentactuator.com
Pcwebopidia.com. (n.d.). Retrieved June 9, 2006 from the website:
Pcwebopidia.com
Remote Satellite Communications. (2006). Retrieved June 9, 2006 from the
website: Spidersat.net
School-resources. (n.d.). Retrieved June 9, 2006 from the website: schoolresources.co
Seattle Robotics Society. (n.d.). Retrieved June 9, 2006 from the website:
seattlerobotics.org
St. Jude. (2006). Retrieved June 9, 2006 from the website: stjude.org
Webopedia.com. (n.d.). Retrieved June 9, 2006 from the website: webopedia.com
Wikipedia.org, (n.d.). Retrieved June 9, 2006 from the website: Wikipedia.org
Standards

Standard #2: Students will develop an
understanding of the core concepts of
technology
 [2.Y]
The stability of a technological
system is influenced by all of the
components in the system, especially
those in the feedback loop.
 [2.FF] Complex systems have many
layers of controls and feedback loops to
provide information.
Standards

Standard #17: Students will develop an
understanding of and be able to select and
use information and communication
technologies.


[17.M] Information and communication systems
allow information to be transferred from human
to human, human to machine, machine to
human, and machine to machine.
[17.Q] Technological knowledge and processes
are communicated using symbols,
measurement, conventions, icons, graphic
images, and languages that incorporate a variety
of visual, auditory, and tactile stimuli.