M e ch atr o ni c Engin e e r ing
Study Objectives
r Introduction to mechatronics
. Modeling and design in mechatronics
. Mechatronictechnoiogies
. Application areas
. Study of mechatronics
1.1 Introduction
The subject of mechatronics concerns the synergistic application of mechanics, electronics, controls, and computer engineering in the development of electromechanical products
and systems through an integrated design approach. A mechatronic system will require a
multidisciplinary approach for its modeling, design, development, and implementation. In
the traditional development of an electromechanical system, the mechanical components
and electrical components are designed or selected separateiy and then integrated, possibly with other components and hardware and software. In contrast, in the mechatronic
approach, the entire electromechanical system is treated concurrently in an integrated
manner by a multidisciplinary team of engineers and other professionals. Naturally, a system formed by interconnecting a set of independently designed and manufactured components will have a lower leve1 of performance than that of a mechatronic system, which
employs an integrated approach for design, development, and implementation. The main
reason is straightforward. The best match and compatibility between component functions
can be achieved through an integrated and unified approach to design and development,
and the best performance is possible through an integrated implementation. Generally, a
mechatronic product rt i11 be more efficient and cost effective, more precise and accurate,
more reliable, more flexible and functional, less mechanically complex, safer, and more
environment friendlv than a non-mechatronic product requiring a similar level of effort in
its development. The performance of a non-mechatronic system can be improved through
sophisticated control, but this is achieved at an additional cost of sensors, instrumentation,
and control hardware and software, and with added complexity.
Mechatronic products and systems include modern automobiles and aircraft, smart
household appliances, medical robots, space vehicles, and office automation devices. In
this chapter, the subject of mechatronics is introduced, important issues in modeling,
design, and the development of a mechatronic product or system are highlighted, and the
associated technology areas and applications are indicated.
Mechqtronics: A Foundation Course
'llllt rr iilx
ilfl
llilllllliiifiil
1.2 Mechatronic Systems
A typical mechatronic svstem consists of a mechanical skeleton, actuators, sensors, controllers, signal conditioning/modification devices, computer/digital hardware and software,
interface devices, and power sources. Different types of sensing, information acquisition,
and transfer are inr.olt ed among all these r.arious types of components. For example, a
servomotor, which is a motor with the capability of sensory feedback for accurate generation of complex motions, consists of mechanical, electrical, and electronic components
(see Figure 1.1). The main mechanical components are the rotor, stator, and the bearings.
The electrical components include the circuitry for the field windings and rotor windings
(not in the case of permanent-magnet rotors) and the circuitrv for porver transmission
and commutation (if needed). Eiectronic components include those needed for sensing
(e.g., an optical encoder for displacement and speed sensing and a tachometer for speed sensing). The overall design
of a servomotor can be improrred bv taking a mechatronic
approach.
The humanoid robot shown in Fisure 7.2a is a more complex and "intelligent" mechatronic sr.stem. It mav involr.e
many servomotors and a variety of mechatronic components, as is clear from the sketch in Fisure 1.2b. A mechatronic approach can greatll' benefit the analvsis/modeling,
design, and development of a complex electromechanical
system of this nature.
In the computer industry, hard-disk drives (HDD; see
Figure 1.3), devices for disk retrieval, access and ejection,
and other electromechanical components can considerably
benefit from high-precision mechatronics. The impact goes
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iriilillr
i
rftittitl
i I rt'lllltlt(ii!11
,,
i]
.n'1,tltff,il
FICURE 1.1
A serYomotor is a mechatronrc
deYice. (Courtesy of Danaher
Motron, Rockford, IL.)
Actuator auxilian
processlng untts
Six-axis force sensor
(a)
(b)
-I.2
FIGURE
(a) A humanoid robot is a complex and "inte1ligent" mechatronic slrstem; (b) components of a humanoid robot.
(Courtesy of American Honcla Motor Co. Inc., Torrance, CA.)
rmgH
lill|w
lll , i tlrlil
r
ourse
\ [ ech a f ronic Engi n eer i ng
Spir-rdle
motor
' +f
Head slider
^l
fare/
iion,
Tracks
'le, a
ieraents
Disk
ngs.
'n irq
rion
Mounting
,ins
--'b
frame
Arm rotor
Arm motor
stator
FICURE 1.3
-\n HDD unit of a computer.
further because digital computers are integrated into a \rast variety of other devices and
mechatronic applications.
Technology issues of a general mechatronic system are indicated in Figure 1.4. It is seen
that they span the traditional fields of mechanicai engineering, electrical and electronic
engineering, control engineering, and computer engineering. Each aspect or issue within
lvlodeling, Anall'sis
Tnfporefed
Svstem
development
dp<ion
Testing and refinement
tasks
Sensors and transducers
Actuators
Controllers
*l
stnrctfi i--l [EIJJ'
t components
"
o
I
Mechatronic
I
svstem
i l(analog/digital)l
E'"'Er-l
T
f- " I
-'
|
ll Jorrware
I sources
I
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tr',r'rril;il-l
t
I
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I Dneumatlc Ll
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ll
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processrng
-
l
Electrical and
computer engineering
FIGURE
,I.4
Concepts and technologies of a mechatronic s1'stem
Mechntronics: A F oundation Course
the system may take a multi-domain character. For example, as noted before, an actuator
(e.g., dc servo motor) itself mav represent a mechatronic device within a larger mechatronic system such as an automobile or a robot.
The study of mechatronic engineering should inciude all stages of modeling, design,
development, integration, instrumentation, control, testing, operation, and maintenance
of a mechatronic svstem.
1.3 Modeling and Design
A model is a representation of a real svstem, and the subject of model development (modeling) is important in mechatronics (see Chapter 3). Modeling and design can go hand-inhand in an iterative manner. Of course, in the beginning of the design process, the desired
system does not exist. In this context, a model of the anticipated system can be very useful.
In view of the complexitv of a design process, particularly when striving for an optimal
design, it is useful to incorporate system modeling as a tool for design iteration particularly because prototyping can become \rerv costly and time consuming.
In the beginning, by knor,ving some information about the system (e.9., intended functions, performance specifications, past experience, and knou'ledge of related systems) and
by using the design objectives, it is possible to develop a model of sufficient (low to moderate) detail and complexity. By analyzing and carrving out computer simulations of the
model, it will be possible to generate useful information that wili guide the design process
(e.g., the generation of a preliminary design). In this manner, design decisions can be made
and the modei can be refined using the ar.'ailabie (improved) design. This iterative link
between modeling and design is schematicallv shon'n in Figure 1.5.
It is expected that the mechatronic approach will result in a higher quality of the products and services, improved performance, and increased reliability while approaching some form of optimality. This n'ill enabie the development and production of
. = \IecI
-
Purpose,
performance specs,
past knowledge, etc
Design
objectives/specs
iri
'.t'c
FIGURE 1.5
Link betn'een modeling and design
- l-.,:
:;1
:
.:.:'. )t1
course
1a actuator
::ar mecha-
:, design,
-ntenance
-
:-:nt (mod-
' :-- hand-in- .:e desired
. =:t'uSefUl.
: -..r optimal
. _:.
particu-
-=-.;ed func-
. -:emS) and
.',". io mod-.:. - :,s of the
Mech atroni c Enginee r i ng
electromechanical systems efficiently, rapidly, and economically. When performing the
integrated design of a mechatronic system, the concepts of energy and power present a
unifying thread. The reasons are clear. First, in an electromechanicai system, ports of
power and energy exist that link electrical dynamics and mechanical dynamics. Hence,
the modeling, analysis, and optimi zation of a mechatronic system can be carried out
using a hybrid system (or multi-domain system) formulation (a model) that integrates
mechanical aspects and electrical aspects of the system. Second, an optimal design will
aim for minimal energy dissipation and maximum energy efficiency. There are related
implications; for example, greater dissipation of energy will mean reduced overall efficiency and increased thermal problems, noise, vibration, malfunctions, wear and tear,
and increased environmental impact. Again, a hybrid model that presents an accurate
picture of the energy/power flow within the system will present an appropriate framework for the mechatronic design. (Nofe: Refer to linear graph models in particular, as
discussed in Chapter 3.)
A design may use excessive safety factors and worst-case specifications (e.g., for mechanical loads and electrical loads). This will not provide an optimal design or may not lead to
the most efficient performance. Design for optimal performance may not necessarily lead
to the most economical (least costly) design, however. When arriving at a truly optimal
design, an objective function that takes into account all important factors (performance,
quality, cost, speed, ease of operation, safety, environmental impact, etc.) has to be optimized. A complete design process should generate the necessary details for the construc-
tion or assembly of the system.
: l:. DTOCeSS
:, ':.e made
-=:,'.::r'e link
::.e prod-
1.4 Mechatronic Design Concept
:.:'proach-
In a true mechatronic sense, the design of a multi-domain multicomponent system will
require the simultaneous consideration and integrated design of all its components, as
indicated in Figure 1.4. Such an integrated and 'toncurrent" design will call for a fresh
look at the design process itseif and also a formal consideration of information and energy
transfer between the components within the svstem.
In an electromechanical system, there existi an interaction (or coupling) between electrical dynamics and mechanical dynamics. Specifically, electrical dynamics affect the
mechanical dynamics and vice versa. Traditionally, a "sequenti al" approach has been
adopted to the design of multi-domain (or mixed) systems such as electromechanical systems. For example, first the mechanical and structural components are designed, next the
electrical and electronic components are selected or developed and interconnected, then
a computer is selected and interfaced with the system, subsequently a controller is added,
-".tion of
and so on. The dynamic coupling between various components of a system dictates, however, that an accurate design of the system should consider the entire system as a whole
rather than designing the electrical/electronic aspects and the mechanical aspects separately and sequentially. When independently designed components are interconnected,
sel'eral problems can arise as follows:
1. When two independently designed components are interconnected, the original
characteristics and operating conditions of the two will change due to the loading
or dynamic interactions (see Chapter 4).
Mechatronics: A F oundation Course
2. A perfect matching of two independently designed and developed components
will be practically impossible. As a result, a component can be considerably underutilized or overloaded, in the interconnected system, both conditions being inefficient and undesirable.
3. Some of the external variables in the components will become internal and "hidden" due to interconnection, which can result in potential problems that cannot be
explicitly monitored through sensing and cannot be directiy controlled.
The need for an integrated and concurrent design for electromechanical systems can be
identified as a primary motivation for the developments in the field of mechatronics.
1.4.1 Coupled Design
An uncoupled design is where each subsystem is designed separately (and sequentially),
while keeping the interactions with the other subsystems constant (i.e., ignoring the
dynamic interactions). Mechatronic design involves an integrated or 'toupled" design.
The concept of mechatronic design may be illustrated using an example of an electromechanical system, which can be treated as a coupling of an electrical subsystem and a
mechanical subsystem. An appropriate model for the system is shown in Figure 1.6a. Note
that the two subsystems are coupied using a loss-free (pure) energy transformer while the
losses (energy dissipation) are integral with the subsystems. In this system, assume that
under normal operating conditions the energy flow is from the electrical subsystem to
the mechanical subsystem (i.e., the electricai subsystem behaves like a motor rather than
a generator). At the electrical port that connects to the energy transformer, there exists a
current I (a "through" variable) flowing in and a voltage z' (an "across" variable) with the
shown polarity (the concepts of through and across variables and the related terminology are explained in Chapter 3). The product zri is the eiectrical power, which is positive
out of the electrical subsystem and into the transformer. Similarl11 at the mechanical port
that comes out of the energy transformer, there exists a torque r la through variable) and
an angular speed ro (an across variable) with the sign convention indicated in Figure 1.6a.
Accordingly, a positive mechanical power ot flows out of the transformer and into the
mechanical subsystem. The ideal transformer implies that
oi=an
Electrical
Mechanical
subsystem
subsystem
Electrical
dynamics
-ffj
-a---r I
Idealenergy
translormer
(0
T
+
Mechanical
_
dynamics
Fnerw
dissipation
|-.
(a)
FICURE 1.6
(a) An electromechanical system; (b) conr.entional design
Energy
dissipation
(1 1)
. -,.ittdation Course
'.
--- -omponents
-. _: -:abh'under-
-. being inef.
.. :':.1 and "hid- .:-:.t cannot be
:''i
:: stems can be
. -:.atronics.
---. sequentially),
- rgnoring the
. chatronic Engine ering
.n a conventional uncoupled design of the system, the electrical subsystem is designed
: . treating the effects of the mechanical subsystem as a fixed load, and the mechanical
--:irsystem is designed by treating the electrical subsystem as a fixed energy source, as
-licated in Figure 1.6b. Suppose that, in this manner, the electrical subsystem achieves an
:timal 'design index" of 1,," and the mechanical subsystem achieves an optimal design
-Jex of 1,,,,,.
\ofs: The design index is a measure of the degree to which the particular design satisfies
. e design specifications (design objectir.es).
\Vhen the two uncoupled designs (subsystems) are interconnected, there will be dynamic
:-:eractions. As a result, neither the electrical design objectives nor the mechanical design
-'jectives will be satisfied at the levels dictated by I,,. and 1,,,n, respectively. Instead, they
-11 be satisfied at lower leveis as given by the design indices I, and 1,,. A truly mechatronic
.::sign lvili attempt to bring 1" and I,,, as close as possible to 1,,. and 1,n,, respectively. This
-av be achieved, for example, by minimizing the quadratic cost function:
,.:led" design.
' . -.f an electro-
-,.:.r-stem and a
- :,tre 1.6a. Note
' ::-.er lvhile the
- .. assume that
.. .,.rbsystem to
. : rather than
- ::.ere exists a
" ,,:-e) r,l'ith the
. .:..i terminol-
' _. 1s positive
- . -:'ar-rical port
:.:iable) and
- ,::gure 1.6a.
' .:- i into the
I = a,(.1,,, - 1,,)t + c1,,,(1,,,,, - 1,,)2
(r.2)
.Li^-+ +^
tl, l
1;;ntr)
L-nl l
(1.3)
,, i-iere
D denotes the transformation that represents the design process
p denotes information including system parameters that is available for the design
Even though this formulation of the mechatronic design problem appears rather simple
:nd straightforward, the reality is otherwise. In particular, the design process, as denoted by
:]re transformation D, can be quite complex and typically nonanalytic. Furthermore, mini:'nization of the cost function / is by and large an iterative practical scheme and undoubtedly
:. knor.t'1edge-based and nonanalytic procedure. This complicates the process of mechatronic
Jesign. In any event, the design process will need the information representedby p.
(1.1)
1.4.2 Mechatronic Design Quotient
\lechatronic svstems are complex and require multiple technologies in multiple domains.
Their optimai design may call for multiple performance indices. The problem of mechatronic design may be treated as a maximization of a "mechatronic design quotient" or
\IDQ. In particular, an alternative formulation of the optimization problem given by (1.2)
and (1.3) wouid be the maximization of the MDQ:
MDo- =
u'I! +a"J?t'
(14)
0'1,1.+ct,,,11,,,,
subject to (1.3).
Even though Equation 1.4 is formulated for two categories of technologies or devices m
and e (and the corresponding indices I, and 1,,,), the MDQ may be generaiized for three or
more categories such as: reliability, maintainability, efficiency, cost effectiveness, power
and efficiency, size and geometry, control friendliness, and level of intelligence. The
Mechatronics: A Foundation Course
corresponding indices may be qualitative or nonanalytic and may have correlations or
interactions. Then, more sophisticated representations (e.g., the use of fuzzy measures)
and optimization techniques (e.g., evolutionary computing or genetic programming or
GP) may be employed in the design process.
For example, in the use of genetic algorithms (GA) for mechatronic design, we start with
a group (population) of initial chromosomes (embryos) where an individual chromosome
is one possible design. An individual gene in a chromosome corresponds to an element of
information in a design (e.g., system component, connection structure, set of parameters,
design attribute). Alleles are possible values of a gene (e.g., availabie choices for a particular component). The "fitness function" of the GA represents the "valLre," "goodness,"
or "fitness" of a design. In the present context, the fitness function is the MDQ, which is
computable for a given design once the element information of the design is known. Then
the problem of design optimization becomes:
Maximize MDQ(pt, p2,..., p,,)
/1 q)
where, p, is the lth design aspect.
The strength and applicability of the MDQ approach stem from the possibility that the
design process may be hierarchically separated. Then, an MDQ may be optimized for
one design layer involving two more technology groups in that layer before proceeding
to the next lower design layer where each technology group is separately optimized by
considering several technology/component groups within that group together with an
appropriate MDQ for that lower-level design problem. For example, an upper layer may
optimize the actuator type for the particular application (e.g, hydraulic, dc, induction,
stepper; see Chapter 7) with an appropriate MDQ. The next lower level may optimize the
motor selection (e.g., select a motor from an available set of dc motors) with another MDQ.
In this manner, a complex design optimization may be achieved through several design
optimizations at different design levels. The final design may not be precisely optimal, yet
intuitively adequate for practical purposes; say in a conceptual design.
1.4.3 Design Evolution
Traditionally, the online monitoring of responses,/outputs of a system may be used to
detect and diagnose the faults and malfunctions (existing or impending) of a system. We
believe that such monitoring may also be used to improve the design of an existing mechatronic system. In particular, just like how a health monitoring system can pinpoint a defective component in a system, it should be possible for the same system to at least identify
the possible regions (sites) of design weakness in the system. This is the premise of the
approach for "design evolution", as outlined below.
A model of the existing system (whose design needs to be improved) and evolutionary computing (GP) may facilitate the approach of "evolutionary" design improvement
through online monitoring. A possible framework for implementing this approach is indicated in Figure 1.7.
The relevant steps are as follows:
1. Develop a model of the existing system.
2. Establish (using a machine health monitoring system and an expert system)
which aspects or segments of the original system (and its model) may be modified/improved using information monitored from the system. These will provide
"modifiable sites" for the existing system/model.
-
:..'. 111 cOLrse
', Iechatronic
Engineering
= -- -,:ielations or
Interface
(for users, domain
r :::, measures)
_: ::amming or
experts, engineers,
etc. )
--
-,,.
Machine health
e start with
monitoring
-' ::rrOmOSOme
svstem
. -::^ element Of
:- .::arametefs/
- -=s tor a par: Eoodness,"
ilQ, rvhich is
: r.ltr\r-fl, Th€ll
(1 5)
- :.--:r that the
Design
:.-nized for
r:::rrceeding
::-nized by
-:.iit tvith an
, : :: a\-ef may
- , rcluction,
:limize the
:- 'rer MDQ.
-. =::.1 design
::imal, yet
improvements
:ICURE,I.7
:::rcture of a system for evolutionary design.
3. Formulate a performance function to represent the "goodness" of the design. This
is the MDQ.
-1. Use an optimization method (CP) to e\rolve the model so as to maximize
the per-
formance function.
5. Implement, in the existing system, the design changes represented by the evolved
modei.
- r.e
optimization scheme will graduaily improve the original model of the system so as
= ,-ised to
:.- produce better performance (as judged by the MDQ). This will require the comparison
.:em. We
,-. mecha-
,. it evolves (improves), with respect to the MDQ. In Figure 1.7, in addition to the initial
:.: a defec- r.-lan+if-'
se of the
: the monitored response of the original system and the simulated response of the model
::'rdel of the system, the er.olutionary computing approach, and online monitoring, we
-:r-e shown an expert system as well for "intelligent" decision making associated with
-:=sign/model improvement. This expert system may be generated from the knowledge/
. ,.:rertise of the existing svstem, its design, and engineering know how.
,'olution:: _.r-ement
^ r; indi-
1.5 Evolution of Mechatronics
.:ient)
::',tr c1i-
: r-,'ide
l.lechanical engineering products and systems that employ some form of electrical engi'=ering principles and devices have been developed and used since the early part of the
'.-entieth century. These systems included the automobile, electric typewriter, aircraft,
. r-.d elevator. Some of the power sources used in these systems were not necessarily electri-:-. but there were batteries and/or a conversion of thermal power into electricity through
Mechatronics: A Foundation Course
10
generators. These "electromechanical" systems were not "mechatronic" systems because
they did not use an integrated approach characterizing mechatronics for their analysis,
design, development, and implementation.
Rapid advances in electromechanical devices and systems were possible particularly due to developments in control engineering, which began for the most part in the
early 1950s, and still more rapid advances in digital computer and communication as a
result of integrated circuit (IC) and microprocessor technologies, starting from the late
1960s. With these advances, engineers and scientists felt the need for a multidisciplinary
approach to design and hence a "mechatronic" approach. ln1969, Yasakawa Electric in
japan was the first to coin the term mechatronics, for which the company obtained a
trademark in 1972. Subsequently, in 7982, the company released the trademark rights.
Even though a need for mechatronics was felt even in those early times, no formal discipline or educational programs existed for the engineers to be educated and trained
in this area. The research and development activities mainly in automated transit systems and robotics in the 1970s and the 1980s undoubtedly paved the way for the evolution of the field of mechatronics. With today's sophisticated technologies of mechanics
and materials, analog and digital electronics, sensors, actuators, controllers, electromechanical design, and microelectromechanical systems (MEMS) with embedded sensors,
actuators, and microcontrollers, the field of mechatronics has attained a high degree of
maturity. Now many universities around the world offer undergraduate and graduate
programs in mechatronic engineering, which have become highly effective and popular
:l
a
among students, instructors, employees, and employers alike.
L.6 Application Areas
The application areas of mechatronics are numerous and involve those that concern multidomain (mixed) systems and particularly electromechanical systems. These applications
may involve the following:
1. Modifications and improvements to conventional designs by using a mechatronic
approach
2. The development and implementation of original and innovative mechatronic
systems
In either category, the applications may employ sensing, actuation, control, signal conditioning, component interconnection and interfacing, and communication, generally using
tools of mechanical, electrical, electronic, computer, and control engineering. Some important areas of application are indicated below.
Transportation is a broad area where mechatronic engineering has numerous applications. In ground transportation, particularly automobiles, trains, and automated transit systems use mechatronic devices. They include airbag deployment systems, antilock
braking systems (ABS), cruise control systems, active suspension systems, and various
devices for monitoring, toll collection, navigation, warning, and control in intelligent
vehicular highway systems (IVHS). In air transportation, modern aircraft designs with
advanced materials, structures, electronics, and control benefit from the concurrent and
-
:,.:.l.ation Course
M ech at ron i c Engin ee ring
:.. :ttnlS beCaUSe
integrated approach of mechatronics to develop improved designs of flight simulators,
flight control systems, navigation systems, landing gear mechanisms, traveler comfort
aids, and the like.
Manufacturing and production engineering is another broad field that uses mechatronic technologies and systems. Factory robots (for welding, spray painting, assembly,
inspection, and so on), automated guided vehicles (AGVs), modern computer-numerical
control (CNC) machine tools, machining centers, rapid (and virtual) prototyping systems,
and micromachining systems are examples of mechatronic applications. High-precision
motion control is particularly important in these applications.
In medical and health care applications, robotic technologies for patient examination,
surgert rehabilitation, drug dispensing, and general patient care are being developed and
used. Mechatronic technologies are being applied for patient transit devices, various diag-
: :..e1r analysis,
.--rie particu-
: :: part in the
-:- _:.:.tcation
as a
-: ::.rm the late
. :.:.rsciplinary
. .:. Eiectric in
, '. obtained a
--
=::.:,rk rights.
:ormal dis-
, - _::,d trained
'- . .:ansit sys-
.
,
: : :he evolu-
-.
:rechanics
=teCtfome-
: - -l-J SenSOIS/
- :: Segree of
, ,: Eraduate
, . -J popular
11
nostic probes and scanners, beds, and exercise machines.
In a modern office environment, automated filing systems, multifunctional copymg
machines (copying, scanning, printing, FAX, and so on), food dispensers, multimedia
presentation and meeting rooms, and climate control systems incorporate mechatronic
technologies.
In household applications, home security systems, robotic caregivers and helpers, robotic
vacuum cleaners, washers, dryers, dishwashers , garage door openers, and entertainment
centers use mechatronic devices and technologies.
The computer industry can considerably benefit from mechatronics. The impact goes
further because digital computers are integrated into a vast variety of other devices and
applications.
_=:r multi: : -tcations
In civil engineering applications, cranes, excavators, and other machinery for building,
earth removal, mixing, and so on will improve their performance by adopting a mechatronic design approach.
In space applications, mobile robots such as NASAs Mars exploration Rover, spacestation robots, and space vehicles are fundamentally mechatronic systems.
It is noted that there is no end to the type of devices and applications that can incorporate mechatronics. In view of this, the traditional boundaries between engineering disciplines will become increasingly fuzzy, and the field of mechatronics will grow and evolve
further through such merging of disciplines.
- -: :lr-tI'IlC
- i .:-lnlc
1.7 Study of Mechatronics
_-,-;ondi-
'. _-.-using
: : -:]1POI-
..
':plica-
. :=,t tran-
- ..r.:ilock
- .: '. arious
- =-,igent
' l s $'ith
- ':=:.i and
Mechatronics is a multidisciplinary field that is concerned with the integrated modeling,
analysis, design, manufacture, control, testing, and operation of smart electromechani,
cal products and systems. Hence, one should not use a 'tompartmentalized" approach
in studying this field. Specifically, rather than using a conventional approach to learning
standard subjects separately in a disjointed manner, they need to be integrated into a common "mechatronics" framework, along with other specialized subjects.
The study of mechatronics requires a good foundation of such core subjects as mechanics, electronics, modeling, control, signal processing and conditioning, communication,
and computer engineering, and specialized subjects like electrical components, mechanical components, sensors and transducers, instrumentation, drives and actuators, intelligent
control, interfacing hardware, software, testing, performance evaluation, and cost-benefit
12
Mechatronics: A F oundation Cours e
analysis. In mechatronics, all these subjects are unified through an integrated approach of
modeling, analysis, design, and implementation for multi-domain systems. A iraditional
undergraduate curriculum in engineering does not provide such a broad and multidisciplinary foundation. A more realistic approach would be to follow a traditional engineering curriculum in the first 2years of a 4year undergraduate program, and then get into an
integrated mechatronic curriculum in the next 2 years. What is presented in this book is
the necessary material in mechatronics that is not traditionally covered in the first 2 vears
of an undergraduate engineering program.
: l l -- iS, ,r'-
1.8 Organization of the Book
The book consists of 10 chapters and 4 appendices. The chapters are devoted to presenting
the fundamentals in electrical and electronic engineering, mechanical engineering, control engineering, and computer engineering, which are tlecessary for formlng the iore of
mechatronics. In particular, they cover modeling, analysis, mechanics, electronics, instrumentation, sensors, transducers, signal processing, actuators, drive systems, computer engineering, control, and system design and integration. The book uniformly incorporates the
underlying fundamentals into analytical methods, modeling approaches, iesign techniques,
and control schemes in a systematic manner throughout the main chapterslThe praciical
application of the concepts, approaches, and tools presented in the introductory chapters
are demonstrated through numerous illustrative examples and a comprehensive set of .ur"
studies. The background theory and techniques that are not directlluseful to present the
fundamentals of mechatronics are given in a concise manner in the appendices.
Chapter 1 introduces the field of mechatronics. The evolution of ttre fieta is given. The
underlying design philosophy of mechatronics and how it relates to modeling is described.
This introductory chapter sets the tone for the study, which spans the reLaining nine
chapters.
Chapter 2 deals with mechanical components, which are important constituents of the
mechatronic system. It also studies electronic components, which form another class of
important constituents of a mechatronic system. Electronic material and both passive and
active electronic components are discussed. Common practical uses of these Components
are indicated.
Chapter 3 deals with the modeling and analysis of dynamic systems. Mechanical, electrical, fluid, and thermal systems and mixed svstems such as electromechanicai systems
are studied. The usual techniques of modeling are presented, while emphasizing those
methods that are particularly appropriate for mechatronic systems. Analysis ln bolh time
domain and frequency domain is introduced, while discussing response analysis and
computer simulation.
Chapter 4 presents the component interconnection and signal conditioning, which is
in fact a significant unifying subject within mechatronics. impedance considerations of
component interconnection and matching are studied. Amplification, filtering, analog-todigital c,onversion, digital-to-analog conversion, bridge ciriuits, and other si[nal .ori.r".sion and conditioning techniques and devices are discussed.
Chapter 5 covers the performance analysis of a mechatronic device or component.
Methods of performance specification are addressed, both in the time domain ind the
frequency domain. Common instrument ratings that are used in industry and generally in
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chatronic Engine ering
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::le engineering practice are discussed. Related analytical methods are given. Instrument
:andwidth considerations are highlighted and a design approach based on component
:andwidth is presented. Errors in digital devices, particularly resulting from signal sam:ling, are discussed from the analvtical and practical points of view.
Chapter 6 presents important types, charaiteristics, and operating principles of sensors
.lnd transducers. Particular attention is given to sensors that are commonly used in mecha:ronic systems. Motion sensors, force, torque and tactile sensors, optical sensors, ultrasonic
sensors/ temperature sensors, pressure sensors, and flow sensors are discussed. Analytical
:asis, selection criteria, and application areas are indicated. Unlike analog sensors, digi:al transducers generate pulses or digital outputs. These devices have clear advantages,
rarticulariy lvhen used in computer-based digital systems. They do possess quantization
errors, which are unavoidable in a digital representation of an analog quantity. The related
-ssues of accuracy and resolution are also addressed in Chapter 6.
Chapter 7 studies the actuators for mechatronic syste*s. In particular, stepper motors
:hat produce incremental motions are studied. Under satisfactory operating conditions,
ihey have the advantage of being able to generate a specified motion profile in an openloop manner without requiring motion sensing and feedback control. Continuous-drive
actuators such as dc motors, ac motors, hydraulic actuators, and pneumatic actuators are
also covered in Chapter 7. The operating principles, analytical methods, sizing and selection considerations, drive systems, and control techniques are described. The advantages
and drawbacks of various types of actuators on the basis of the nature and the needs of an
application are discussed and practical examples are given.
Chapter 8 covers digital logic and hardware, microprocessors, and microcontrollers,
rvhich fall within the area of electronic and computer engineering. Logic devices and ICs
are widely used in mechatronic systems for such purposes as sensing, signal conditioning, and control. The basic principles of digital components and circuits are presented
in this chapter. The types and applications of logic devices are discussed. The technology of ICs is introduced. The microcontroller and the embedded microprocessor have
become standard components in a large variety of mechatronic devices. A microprocessor
together with memory, software, and interface hardware (i.e., a microcontroller) provides
an effective and economical miniature digital computer in mechatronic applications. Smart
sensors, actuators, controllers, and other essential components of a mechatronic system
can immensely benefit from the programmability, flexibility, and processing power of a
microcontroller.
Chapter 9 deals with the control of mechatronic systems. Both time-domain techniques
and frequency-domain techniques of control are covered. In particular, performance
specification, stability analysis, and control schemes are presented. Underlying analytical
methods are described. The popular approach of inteiligent control, known as fuzzy logic
control, is presented. Popular advanced techniques of control are outlined.
Chapter 10 concludes the main body of the book by presenting the design approach of
mechatronics and by giving extensive case studies of practical mechatronic systems. The
techniques covered in the previous chapters come together and are consolidated in these
case studies, Several design exercises and practical projects in mechatronics are given.
The four appendices provide some useful fundamentais, techniques, and tools for
the study of mechatronics in a concise and condensed form. Appendix A presents the
basic theory of solid mechanics and elasticity. Appendix B gives useful techniques of the
Laplace transform and Fourier transform. Appendix C outlines the basics of probability
and statistics. Appendix D presents several useful software tools. In particular, Simulink@
and MATLABo toolboxes of control systems and fuzzy iogic are outlined. The LabVIEW@
Mechatronics: A Foundation Course
T4
program development environment, which is an efficient tool for laboratory experimentation (particularly, data acquisition and control) is described.
Problems
1.1 The following have been claimed as benefits of the mechatronic design of a system:
o Optimality and better component matching
. Ease of system integration and enhancement
o Compatibility and ease of cooperation with other systems
o Increased efficiency and cost effectiveness
. Improved controllability
r Improved maintainability
. Improved reliability and product life
. Reduced environmental impact
Briefly justify each of these claims.
1.2 You are a mechatronic engineer who has been assigned the task of designing and
instrumenting a mechatronic system. In the final project report, you will have to
describe the steps of establishing the design/performance specifications for the system, selecting and sizing sensors, transducers, actuators, drive systems, controllers,
signal conditioning and interface hardware, and software for the instrumentation
and component integration of this system. Keeping this in mind, write a project proposal given the following informaiion:
1. Select a process (plant) as the system to be developed. Describe the plant indicating the purpose of the plant, how the plant operates, what is the system boundary
(physical or imaginary), what are important inputs (e.g., voltages, torques, heat
transfer rates, flow rates), response variables (e.g. displacements, velocities, temperatures, pressures, currents, voltages), and what are important plant parameters (e.g., mass, stiffness, resistance, inductance, conductivity, fluid capacity). You
may use sketches.
2. Indicate the performance requirements (or operating specifications) for the plant
(i.e., how ihe plant should behave under control). You may use any available
information on such requirements as accuracy, resolution, speed, linearity, stability, and operating bandwidth.
3. Cive any constraints related to cost, size, weight, environment (e.g, operating
temperature, humidity, dust-free or clean room conditions, lighting, wash-down
needs), etc.
4. Indicate the type and the nature of the sensors and transducers present in the
plant and what additional sensors and transducers might be needed for properly
operating and controlling ihe system.
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.;:ronic Engineering
15
= lrrdicate the type and nature of the actuators and drive systems present in the
prlant and r.r'hich of these actuators have to be controlled. If you need to add new
actuators (including control actuators) and drive systems, indicate such requirements in sufficient detail.
r \{ention what tvpes of signal modification and interfacing hardware wouid be
needed (i.e., filters, amplifiers, modulators, demodulators, ADC, DAC, and other
tlata acquisition and control needs). Describe the purpose of these devices. Indicate
any software (e.9., driver software) ihat may be needed along with this hardware.
=n of a system:
- h-Ldicate the nature and operation of the controllers in the system. State whether
::r.ese controllers are adequate for your system. If you intend to add new control-
=:s, briefly give their nature, characteristics, objectir,'es, etc. (e.g., analog, digital,
:',ear, nonlinear, hardware, software, control bandwidth).
lescribe how the users and/or operators interact with the system, and the nature
.ri the user interface requirements (e.g., graphic user interface or GUI).
Ihe foliowing plants/systems mav be considered:
1. A hvbrid electric vehicle
2. A household robol
3. A smart camera
' -:esigning and
:1. A smart airbag svstem for an automobile
,r rvill have to
5. Rover mobile robot for Mars exploration developed by NASA
:'s for the sys:-s, controllers,
6. An AGV fora manufacturingplant
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8. A hard disk drive for a personal computer
7. A flight simulator
9. A packaging and iabeling svstem for a grocery item
: :rrt indicat. :-. boundary
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10. A vibration testing system (electrodynamic or hydrauiic)
11. An active orthotic device to be r,r'orn by a person to assist a disabled or weak hand
(r.t'hich has some sensation, but is not fully functional)
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Further Reading
-ris book has relied on many publications, clirectly and indirectly, in its development and evolution.
Many of these publications are based on the work of the author and his coworkers. Also, there
are some excellent books the reader mav refer to for further information and knowledge. Some
selected books are listed belorr'.
:-itslander, D.M. and Kempf, C.J., Meclntronics Mechnnicnl System Intert'acing, Prentice Hall, Upper
Saddle Rivea NJ, 1996.
Itrlton, \N., Mechttronics,2nd edn., Longman, Essex, England, 1999.
-q.tinkunt, 5., Mechntronics, John lVi1ey & Sons, Hoboken, NJ, 2007.
-iren, B.M., Lee, T.H., and Venkataramenan, Y., Hnrd Disk Driae Seroo Systems, Springer-Verlag,
London, Engiand,2002.
76
Mechqtronics: A F oundation Course
Histand, M.B. and Alciatore, D.G., Introduction to Mechatronics and Measurement Sqstems, Y,{CB
McGraw-Hill, New York, 1999.
Jain, L' and de Si1va, C.W. (Eds.),Intelligent Adaptioe Control: Industrial Applications, CRC Press, Boca
Raton, FL,1999.
Katray, F. and de Silva, C.W., Soft Computing and Intelligent Systems Design, Addison Wesley, pearson,
New York,2004.
Necsulescu, D., Meclntronics, Prentice Hall, Upper Saddle Rivea N|, 2002.
Shetty, D. and Kolk, R.A., Mechatronics system Design, pws publishing Co., Boston, r.y'rA, 1997.
de Silva, C.W. and Wormley, D.N., AutomatedTransit Guideways: Analysis and Design, D.C. Heath and
Co., Simon & Schuster, Lexington, MA, 1983.
de Silva, C.W. Dynamic Testing and Seismic Qualit'ication Practice, D.C. Heath and Co., Simon &
Schuster, Lexington, MA, 1983.
de silva, C.w., Control sensors and Actuators, Prentice-Hall, Englewood cliffs, NJ, 19g9.
de Silva, C.W and MacFarlane, A.G.I., Knowledge-Based Control zuith Apptication to Robots, SpringerVerlag, Berlin, Germany, 1989.
de silva, C.w.,Intelligent Control-Fuzzy Logic Applications, CRC press, Boca Raton, FL, rg95.
de Siiva, C.W. (Ed.), Iir telligent Machines: Myths and Realities, Taylor & Francis/CRC Press, Boca Raton,
FL,2000.
de Silva, C.W., Mechatronics-An Integrated Approach, Taylor & Francis/CRC press, Boca Raton, FL,
2005.
de Silva, C.W. (Ed.), Vibration and Shock Handbook, Taylor & Francis,/CRC press, Boca Raton, FL,
2005.
de silva, C.w., vibration Fundnmentnls and Practice, 2nd edn., CRC press, Boca Raton, FL,2007.
de Silva, C.W., Sensors nnd Actuators-Control System Instrumentation, TayIor & Francis/CRC press,
Boca Raton, FL,2007.
de Silva, C.W. (Ed.), Mechatronic Systems-Deaices, Design, Control, Operation, and Monitoring,Taylor
& Francis/CRC Press, Boca Raton, FL,2007.
Smaili, A. and Mrad, F., Applied Mechatronics, oxford University press, oxford, England, 200g.
Tan, K.K., Lee, T.H., Dou, H, and Huang, s., precision Motion Control, springei-verlag, London,
England,2001.
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