Systems & Mechatronics
(Peter
Kindlmann peter.kindlmann@yale.edu
visits ME185, 3/19/01)
Mechatronics: an
approach to engineering and engineering design which integrates mechanical,
electrical and electronic, and software engineering together with information
technology within a wide range of products and processes. (Here is one of many
introductory articles on the Web http://www.memagazine.org/backissues/may97/features/mechtron/mechtron.html
My favorite search
engine these days is www.google.com)
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Origins
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"Mechatronics" term
coined around 1970.
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Microelectronics and
mechatronics was vigorously embraced by Japanese manufacturers after 1973 oil
crisis as part of a shift away from heavy industry.
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The "Systems Viewpoint"
(Mechatronics will almost invariably be spoken of in the context of a
"system".) Let us give this term some sense of context.
1.
What does a system consist of?
2.
Sensors, Actuators, Controller
3.
The controller implements a decision making process; this can involve a
"gain", solution of a differential equation, a logic condition, a
look-up table, usually more than one such attribute.
4.
almost invariably, all these systems components need a separate source of
power (electrical, pneumatic, hydraulic, possibly optical). In some cases power
can be "scavenged" from the operating environment.
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External
("natural", not designed) Environment
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In the largest sense this is
Nature, where Natural Science reigns, with its quest for knowledge about natural
objects and phenomena.
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But in a more local context it
is the setting within which our mechatronic system operates.
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And in the real world this
situation is often "nested", i.e. a system on a given level usually
operates within an "external environment" that is itself designed,
man-made. E.g. a mechatronic design in the form of a harvesting machine/robot
operates on a farm, which is itself hardly nature in the raw, but is a designed
environment.
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Thus it is typical to find
situations with a "hierarchy of systems," nested one within the other.
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Internal
(man-made, designed, "artificial") Environment
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Except when we go into
"wide-open spaces" on vacation, we live in an entirely man-made world.
Almost every facet of our environment is controlled (temperature, humidity,
etc.) The building in which we are meeting is temperature controlled.
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If I now operate a laboratory
instrument inside this building with even more refined aspects of temperature
control, then this system is "nested" within the "external"
environment in the building interior.
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Block
diagrams are usually used to describe the model of a system
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describes structure
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describes the mathematics used
to model the system
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a block diagram can be used to
understand a system both physically and mathematically
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System "Philosophical" Issues
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A system's description, its
'specification', can be thought of as an 'interface' between the outer
environment within which it operates and its 'inner' environment, the substance
and organization of the system itself.
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Usually the system's
specificational description abstracts from the external environment only a
limited number of understood salient features. Other, neglected, aspects of the
environment may impinge unexpectedly. But since a system's 'external'
environment may in fact be a larger system's internal workings, this hazard of
unexpected sensitivities can be moderated.
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This is the general idea of a
"system hierarchy."
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An educated person can benefit
from a general systems viewpoint because it will allow him/her to recognize the
frequent similarity between very different contexts, e.g. a fluid flow control
model may be similar to an economics flow of funds model.
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Recognition in such situations
of "families of systems" can engender great economy of thought and a
unified analytical approach. Extensions of this thinking in the form of a
General Systems Theory is the basis of what you may have heard referred to as
"cybernetics." (E.g. see Gerald Weinberg "Introduction to General
Systems Thinking", Wiley 1974)
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Thinking in terms of system
models is arguably the defining
characteristic of engineering.
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Examples of Mechatronic Systems
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turbine
generator in power plant
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automotive
systems are richly mechatronic (as
many as 30 such systems in modern cars). Of these the most prominent are
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electronic ignition and other
aspects of engine control (emission control standards made them indispensable)
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transmission and cruise control
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anti-lock brakes
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control of 'bodily functions'
(windows, power-lock, automatic wipers, climate control, seat adjustments)
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in the automotive example the
systems context extends almost seamlessly to larger scales. I.e. increasingly
intelligent vehicles become part of larger transportation system coordination, e.g. see http://www.computer.org/intelligent/articles/intelligent_vehicles.htm
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"Fly-by-wire"
aircraft (e.g. Boeing 777)
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multiply-redundant
computer control system translates pilot control input into actual electric and
hydraulic activation of plane rudder, flaps, etc. (over 2 million lines of code
in the 777)
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introduction of "drive by wire" now planned for cars, where the
cost of high redundancy will greatly irritate manufacturers.
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Cameras
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really
almost any modern technological product
is to varying degrees mechatronic.
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Features of Mechatronic Systems
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Mechatronics is inherently
interdisciplinary, requiring a
range of knowledge usually beyond that of a single person, except in simple
systems. Thus mechatronics is more inherently a team effort.
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Failure of modern mechatronic
systems relying on electronic components is typically more abrupt and total than
with older electromechanical systems, unless redundancy is used (as in the Boeing 777).
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It is difficult to learn
mechatronic design well, except "on the job."
•
EE 226a/227La "Introduction to Electrical Engineering"
will
be your exposure in miniature to some mechatronic themes, with the EE227La lab
centered on a mobile robot platform.
•
There will also a more advanced mobile robots and autonomous systems course,
EE350b.
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A few interesting Web gleanings
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Innovative mechatronics for
surgery
http://www.zess.uni-siegen.de/pb4/mitsi.htm
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"Smart" airplane
wings for damping turbulence
http://www.bu.edu/quantum/spring2000/feature060.html
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One of many introductory
Mechatronics courses
The ME185 One-Minute Anonymous
Quiz
At
the end of class, I will give you a couple of minutes to write down brief
answers to these questions. Please deposit the paper by the door as you leave.
1.
What is the big point, the main idea, that you learned in class today?
2.
What is the main unanswered question as you leave class today? What is (or are)
the
"muddiest" point(s)?