Bichop R.H. (Ed.) Mechatronic Systems, Sensors, and Actuators: Fundamentals and Modeling
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6-4 Mechatronic Systems, Sensors, and Actuators
based on. Mechatronics can never be about knowing a little something about everything; mechatronics is
about being able to make use of this “everything.” Mechatronics is regarded by some as a philosophy [6],
or as the ability to design products, which points toward legitimacy built on functional skills rather than
formal knowledge.
A comparison will here be made with other subjects. Medicine for example, has been a subject under-
going major change since the 1960s. Before this, medicine on a university level was regarded with a
formal legitimacy. The requirements were mainly defined by government agencies, which stipulated a
list of courses and credits that students should have taken to be able to become a physician. Many of
these requirements were based on formal knowledge in disciplinary subjects, such as chemistry and
anatomy. In the 1960s, in Canada, the first courses and programs organized according to problem-based
learning (PBL) emerged. The idea was to move from a formal legitimacy toward a functional legitimacy.
The PBL programs focused on a problem, such as a disease or a patient showing certain symptoms, and
thereby on the ability to diagnose a patient. The requirements changed from “knowing a certain number
of indicators” to “recognizing symptoms” and “being able to diagnose.”
In the case of mechatronics, one problem that arises is that most of the subjects that mechatronics
rely on are regarded with a formal legitimacy and a disciplinary identity, and it is therefore difficult to
apply a completely different mindset on the subject of mechatronics. This is, however, not unique to
mechatronics. In medicine, the ability to recognize symptoms and diagnose diseases relies on utilization
of formal knowledge in disciplinary subjects, such as chemistry.
6.4 The Selection of Mechatronics
The third question, the selection of mechatronics, can be described as “What should we teach?” or
“How should we choose which material to include in our mechatronics courses?” As with the earlier
questions, this can be viewed in the light of two extremes—horizontal representation or vertical
exemplification.
Horizontal representation means that we choose to teach “something of everything.” Each aspect of the
subject should be represented in some way; all aspects should be covered in the mechatronics program.
The opposite—vertical exemplification means that we choose certain aspects of the subject that we exem-
plify; we teach “everything of something.” An example: a basic course in computer programming could
teach something of many programming languages. The course could cover general programming and the
major differences between some languages. The opposite, vertical exemplification would imply that the
course focuses completely on one language, one platform, and so forth, with the objective that students be
exceptionally qualified in one language. There are certainly advantages and disadvantages with both
extremes, and the most preferable solution that most teachers adopt is to try to cover both. We usually
want our students to master at least one language, but also to have knowledge about programming in
general.
However, there are major differences between these two approaches. The vertical exemplification means
that you study details; you become an expert in one narrow field. The horizontal representation means
that the student never gets the opportunity to study details, to become an expert. The idea of vertical
exemplification is that it is always easier to move from a detailed level to the whole picture than the
opposite. If you master one programming language very well, it is rather easy to learn another, but no
matter how much theoretical, broad knowledge you have about programming languages in general, you
will not immediately be able to apply this knowledge and to transfer the knowledge into programming
skills unless utilizing previous related experiences and practices in programming.
When applying the identity and legitimacy of mechatronics to the question of selection, the answer is
rather obvious. Since mechatronics has a thematic identity and a functional legitimacy, the selection ought
to be a vertical exemplification. The reason is that the thematic identity was based on the fact that we do
not agree on what mechatronics is. We do not have a common curricula; no textbook that we consider
in mechatronics covers the field, as we define it. The subject is not established in the surrounding society.
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Mechatronics Engineering Curriculum Design 6-5
The functional legitimacy was based on the fact that the hiring industry does not consider formal curricula
or require a certain number of textbooks or courses to have been taken. Basically, the industry does not
have a clear view of what a mechatronics engineer should or could have studied. Instead, the hiring
industry considers functional skills paramount. These skills then relate to the themes used to describe the
identity. If we use robotics to describe what we mean with mechatronics (as a theme), the hiring industry
should hire students with skills and abilities in robotics to design, implement, or operate robots. Therefore
our selection ought to be exemplifying—a student who is really good and experienced in designing and
building a robot is more desirable than a student with a broad knowledge in robotics, no matter how
broad the overview is. That is, if the identity of the subject is related to this synergistic use. If the identity
is disciplinary and the legitimacy is related to formal knowledge, then knowledge about robots is sufficient.
Mechatronics is, however, not knowledge about mechatronics; mechatronics is knowledge and skills in
mechatronics.
6.5 The Communication of Mechatronics
The fourth and final question relates to “How we should teach?” and “How the material that we select
should be communicated between the faculty and the students?” Either we use a communicational model
based on an active communication or an interactive communication.
An interactive communication implies that what is communicated is dependent on the recipient. What
the teacher is communicating depends on the level of understanding of the student, of the existing
knowledge and skill with each particular student, and of the response of the previous communication.
Interactive communication is communication with feedback.
Historically, most educational communication in our universities is based on the active model. What is
said in lectures, for example, is usually based on a model of student behavior and level of understanding—it
is really difficult to make a lecture interactive with each student. However, there is more to education than
lectures. A student performing experiments, building prototypes, and doing other hands-on activities
usually adapt an interactive mode.When the student chooses how to perform the experiment and how to
build the prototype, this can be regarded as an interactive communication between the student and the
faculty, especially since the communication between the students and teachers tend to be driven by the
students’ own questions and the students’ problems.
The didactical analysis therefore motivates a move from traditional lectures, textbooks, and courses
toward problem-based, project-organized courses, experimental work, and hands-on approaches. This
move should also reflect the selection, legitimacy, and identity of the subject. The projects, problems,
and activities should then exemplify the theme of the subject. A mechatronics student could, for example,
very well be designing, implementing, and operating robots in a mechatronics course—without lectures,
textbooks, and exams in mechatronics theory.
6.6 Fine, but So What?
So far most people usually agree. We can accept that the subject has a thematic identity, we buy the
functional legitimacy, and the vertical exemplifying and interactive communication seems fair. However,
typical courses at the university level show completely opposite characteristics, as shown in Figure 6.2.
Mechatronics has a thematic identity, based on the concept of synergy. Examples of themes are robotics,
embedded systems, and intelligent products. However, universities are organized in traditional disciplines.
Educational programs and courses are usually categorized according to subjects and not themes. A
traditional academic subject usually has higher status than a new, applied cross-disciplinary subject.
Mechatronics has a functional legitimacy. The usual requirements are related to abilities to apply
knowledge and skills, to synthesis rather than analysis; the ability to design and implement a robot,
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6-6 Mechatronic Systems, Sensors, and Actuators
for example. However, most traditional subjects rely on a formal legitimacy. The requirements on the
programs and courses are usually not specified by the industry, but rather directed by the faculty. A typical
exam does not usually measure functional skills.
Mechatronics should therefore be taught with an exemplifying selection. Students should be experts
in synergistic combination by practicing this. However, most traditional courses tend to give overviews
of the subjects, to cover several aspects if not all. Most courses are general rather than specific.
Mechatronics should be taught in an interactive mode. This means that mechatronics courses should
be problem based and project organized. The courses should enable the students to delve deep into, for
example, the design of a robot. However, most courses are communicated with traditional methods such
as lectures, textbooks, seminars, and written exams. This is the de facto situation at most universities
today.
One conclusion from the didactical analysis is that it is not so much a matter of “What?” as of “How?”
Discussions of how to teach mechatronics should be more about educational methods than content.
The content is certainly important, but not as important as the educational methods. This relates also
to the discussion whether the mechatronics engineer is a generalist or a specialist. If the focus is on
content and not enough focus is put on the educational methods, the mechatronics engineer risks being
an engineer with knowledge in some subjects, but without the possibility to compete with subject
specialists, such as electrical engineers. The market for these generalist mechatronics is small, perhaps
only small companies without possibilities of hiring specialists in each subject.
On the other hand, the mechatronics engineer who is a specialist in the synergistic combination of
electrical engineering, mechanical engineering, automatic control, and so forth, will be able to utilize
knowledge and expertise with specialists, as well as his own (though limited) competence in each area.
The creation of these engineers requires appropriate educational methods and a major focus on skills
such as project management, leadership skills, and communicational skills.
6.7 Putting It All Together in a Curriculum
One result of the above analysis is the conclusion that it is neither possible nor fruitful to attempt to
establish a common curriculum in mechatronics until a consensus on the identity and legitimacy is
reached. This is most probably also the reason why most of these attempts fail and why it is so difficult
to agree on a curriculum. Each participant in the discussions has a different perception of required
courses one should take.
To make matters evenmore complicated, imagine the following: A large capstone course is given during
the final year of amechatronics masters’ program. The students are working on a large-scale project with
a corporate sponsor. The project is about designing a rather complex mechatronic product and finalizing
a functional prototype. In a sense, the educational result of the course is reflected in the success of finalizing
the project, since this implies motivated students and gives immediate feedback. The success of the project
FIGURE 6.2 Illustration of the didactic analysis applied to the subject of mechatronics.
Functional
Legitimacy
Identity
Thematic Disciplinary
Formal
Interactive
Communication
Selection
Exemplification Representation
Activ e
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Mechatronics Engineering Curriculum Design 6-7
is however related to the diversity of the students rather than the optimal curriculum. The success of the
project usually requires more skills and competencies than one curriculum can cover, but with a diverse
team these skills can be distributed among several members. The project benefits greatly if at least one
student has good leadership skills and if individual students have expertise in various areas. A homogenous
student team does not reflect a work-like setting and therefore does not prepare students for a future
career as mechatronics engineers.
Naturally, there has to be a common denominator for mechatronics engineers. To be able to create
synergistic combination requires that you have something to combine. Previous studies of mechatronics
educational programs, however, give the following conclusions [6–9].
Most mechatronics programs have evolved from a mechanical engineering perspective; as a special-
ization in a program in mechanical engineering, from an engineering design faculty team, or as a result
of moving from analysis of mechanical systems to synthesis and product development. In these programs,
the students usually have a high competence in mechanical engineering with some courses in electrical
engineering, automatic control, computer science, and so forth. These programs are the most common,
and appear to be the most in line with the thematic identity and functional legitimacy.
Some mechatronics programs have developed from an electrical engineering point of view, or from
programs in computer science. These programs tend to focus more on analysis and theory, than the
programs evolving from mechanical engineering, and less on project work and teamwork.
At some universities, mechatronics programs have been established and developedmore detached from
existing programs. It is primarily in these settings that the discussions of the optimal curriculum are the
most common.
When applying the discussion of the selection of mechatronics to the argument presented above, it is
more important to apply depth than width. The first two scenarios above commonly imply that the
students first study for a BSc in eithermechanical engineering or electrical engineering and then continue
to specialize in mechatronics on a master’s level. The opposite approach, to start with mechatronics from
the very beginning, is much more difficult. It is difficult to make synergistic combinations, and students
often will not be able to get to the detailed level required for a vertical exemplification and finish as
generalists rather than the wanted specialist.
6.8 The Evolution of Mechatronics
The previous discussion regarding the didactical analysis and the “four questions” will be put into per-
spective by adding the dimension of time, to discuss how primarily the identity of a subject changes
over time. The idea is that most traditional subjects are characterized as disciplinary and newer; cross-
disciplinary subjects are more often characterized as thematic. Figure 6.3 was introduced recently to
describe the evolution of the subject of mechatronics [7]. Some evidence of this model can be observed
when studying how newer subjects have emerged on the basis of certain needs and on existing disciplines,
which, for example, is the case for the subjects of strength of materials, solid mechanics, or automatic
control. To illustrate, consider automatic control, a theme that emerged in the early-twentieth century.
In this case, the originating disciplines were electrical engineering and physics. Automatic control has
since developed into a well-established academic subject; thus, the original theme has been further
developed and a research discipline has emerged [10].
The six stages, as shown in Figure 6.3, will here be described further.
6.8.1 Stage 1: The Origin; No Interaction
In this stage, no interaction exists between the original subjects. Usually these are subjects with a
disciplinary identity, but could as well have thematic identities. In the case of mechatronics, the original
subjects are represented mainly by electrical engineering, mechanical engineering, and computer science,
which in this case are considered with a disciplinary identity.
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6-8 Mechatronic Systems, Sensors, and Actuators
6.8.2 Stage 2: Multidisciplinary Stage
This is the first stage of the new subject, in this case of the evolution of mechatronics. Characteristics of
this stage are that students are actively taking courses from different disciplines and areas, to either
broaden their knowledge or to actively specialize in the new cross-disciplinary area. Typically, courses in
electrical engineering are offered to mechanical engineering students or vice versa. The educational system
is still functioning according to disciplines, which in many ways does not facilitate these alternative study
patterns. In this second stage the theme has been identified, which in the case of mechatronics is about
utilizing the various courses into a synergistic combination. An example would be students who choose
to take a course in automatic control just to be able to design an embedded control system for a project
in a design course.
6.8.3 Stage 3: Cross-Disciplinary Stage
In this stage, efforts are put in place by the university to organize activities. Courses are tailor-made for
specific purposes; courses in automatic control are given specifically for mechanical engineering students
with a hands-on approach and based more on applicability and implementation than theory. Courses
in mechanical engineering for electrical engineering students focus more on modeling for a controller
perspective. Courses in applied programming are focused on how to program a certain microcontroller,
and so forth. Also, new courses are created, for example, cross-disciplinary courses such as mechatronics.
6.8.4 Stage 4: Curriculum Stage
In this stage, new programs are created to accommodate the interest and need for the new subject.
Typically, MSc programs are created and offered to mechanical engineering and electrical engineering
students. Also, BSc programs are created in some cases. Characteristics of this stage are the fact that the
faculty is comprised of teachers with a disciplinary background. Usually, the faculty is mixed with
competencies in various areas such as automatic control, mechanical, and electrical engineering.
FIGURE 6.3 A framework for discussing the evolution of academic subjects. The boxed numbers are referred to
in the headings below.
(1) Disciplinary identities
(2) Multidisciplinary (3) Cross-disciplinary (4) Curriculum (5) Organization
(6) Thematic identity
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Mechatronics Engineering Curriculum Design 6-9
6.8.5 Stage 5 and 6: Organizational Stage
The idea of the organizational stage is that students are graduating in the new subject, and later hired
as new faculty. The idea is that the final stage is not reached until the faculty is based on people who
actually specialized in mechatronics.
6.9 Where (and What) Is Mechatronics Today?
An attempt to place a number of universities on an evolutionary scale was attempted in [7], but it basically
does not show much more than the authors’ limited knowledge of the various universities. There are
also some difficulties with the final stages of the model, which will be discussed here.
The faculty does not necessarily need to be specialized in mechatronics. The faculty should offer an
education based on the didactical analysis—based on an exemplifying selection and an interactive com-
munication. This should give students functional skills in mechatronics, meaning that the students should
be able to synergistically combine knowledge and skill in various subjects. The students should be
preparing for a future career in a mechatronics industry, all according to the didactical analysis.
The professors do not need to be skilled experts of synergistic combination of knowledge and skills.
Compare with the coach metaphor; the athletic coach is not required to perform as well as his/her student.
The coach is required to be an expert in how to guide the student to perform well. The mechatronics
professors can instead be experts in the various fields and areas that mechatronics is built on: automatic
control, microcontrollers, electrical engineering, and so forth. However, the professors then also need to
be experts in the process of training students on how to perform this synergistic combination, and one
way of gaining this expertise is to base the knowledge on own experience, just like many athletic coaches
are former athletes.
This can also be seen as a clarification of the fifth and sixth stages of the evolution. Not until the
thematic identity of mechatronics is fully grasped and understood, to the point that professors are
transformed to coaches guiding students in synergistic combination of knowledge, will it be fruitful to
discuss “new organizations.” These professors then are the ones that these new organizations are built on.
References
1. Dahlgren, L. O.,Undervisningen och det meningsfulla lärandet. In Swedish only. Linköping University,
1990.
2. Comerford, Sr. R. (Ed.), Mecha. . .what? Spectrum IEEE, 31(8): 46, 1994.
3. Harashima, F., Tomizuka, M., and Fukuda, T., Mechatronics—what is it, why and how? An editorial,
IEEE/ASME Trans Mechatronics, 1: 1, 1996.
4. Erkmen, A. M., Tsubouchi, T., and Murphy, R., Mechatronics education, IEEE Robot Automat Mag,
8(2): 4, 2001.
5. Craig, K., Is anything really new in mechatronics education? IEEE Robot Automat Mag, 8(2): 12,
2001.
6. Grimheden, M. and Hanson, M., What is mechatronics? Proposing a didactical approach to
mechatronics. In Proc. 2nd European Workshop on Education in Mechatronics, Kiel, Germany, 2001,
p. 97.
7. Grimheden, M. and Hanson, M., Mechatronics—the evolution of an academic discipline in engi-
neering education, Mechatronics, 15(2): 179, 2005.
8. Grimheden, M. and Törngren, M., What is embedded systems and how should it be taught? ACM
Trans Embe dded Computing Sy s, 4: 3, 2005.
9. Wikander, J., Törngren, M., and Hanson, M., The Science and education of mechatronics engi-
neering, IEEE Robot Automat Mag, 8(2): 20, 2001.
10. Abramovitch, D. Y. and Franklin, G. F., Fifty years in control—the story of the IEEE control systems
society, IEEE Control Syst Mag, 14: 19, 2004.
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II
Physical System
Modeling
7 Modeling Electromechanical Systems
Francis C. Moon ........................................................................................................................... 7-1
Introduction
•
Models for Electromechanical Systems
•
Rigid Body Models
•
Basic
Equations of Dynamics of Rigid Bodies
•
Simple Dynamic Models
•
Elastic System
Modeling
•
Electromagnetic Forces
•
Dynamic Principles for Electric and Magnetic
Circuits
•
Earnshaw’s Theorem and Electromechanical Stability
8 Structures and Materials
Eniko T. Enikov .................................................................................................................... 8-1
Fundamental Laws of Mechanics
•
Common Structures in Mechatronic Systems
•
Vibration and Modal Analysis
•
Buckling Analysis
•
Transducers
•
Future Trends
9 Modeling of Mechanical Systems for Mechatronics Applications
Raul G. Longoria ................................................................................................................... 9-1
Introduction
•
Mechanical System Modeling in Mechatronic Systems
•
Descriptions of
Basic Mechanical Model Components
•
Physical Laws for Model Formulation
•
Energy
Methods for Mechanical System Model Formulation
•
Rigid Body Multidimensional
Dynamics
•
Lagrange’s Equations
10 Fluid Power Systems
Qin Zhang and Carroll E. Goering ..................................................................................... 10-1
Introduction
•
Hydraulic Fluids
•
Hydraulic Control Valves
•
Hydraulic Pumps
•
Hydraulic Cylinders
•
Fluid Power Systems Control
•
Programmable Electrohydraulic
Val ve s
11 Electrical Engineering
Giorgio Rizzoni ................................................................................................................... 11-1
Introduction
•
Fundamentals of Electric Circuits
•
Resistive Network Analysis
•
AC
Network Analysis
12 Engineering Thermodynamics
Michael J. Moran ................................................................................................................ 12-1
Fundamentals
•
Extensive Property Balances
•
Property Relations and Data
•
Vapo r a nd
Gas Power Cycles
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13 Numerical Simulation
Jeannie Sullivan Falcon ..................................................................................................... 13-1
Introduction
•
Common Simulation Blocks
•
Textual Equations within Simulation Block
Diagrams
•
Solvers
•
Simulation Timing
•
Visualization
•
Hybrid System Simulation
and Control
14 Modeling and Simulation for MEMS
Carla Purdy ........................................................................................................................ 14-1
Introduction
•
The Digital Circuit Development Process: Modeling and Simulating
Systems with Micro- (or Nano-) Scale Feature Sizes
•
Analog and Mixed-Signal Circuit
Development: Modeling and Simulating Systems with Micro- (or Nano-) Scale Feature
Sizes and Mixed Digital (Discrete) and Analog (Continuous) Input, Output, and Signals
•
Basic Techniques and Available Tools for MEMS Modeling and Simulation
•
Modeling
and Simulating MEMS, That Is, Systems with Micro- (or Nano-) Scale Feature Sizes,
Mixed Digital (Discrete) and Analog (Continuous) Input, Output, and Signals, Two-and
Three-Dimensional Phenomena, and Inclusion and Interaction of Multiple Domains and
Te c h n o l o g i e s
•
A “Recipe” for Successful MEMS Simulation
•
Conclusion: Continuing
Progress in MEMS Modeling and Simulation
15 Rotational and Translational Microelectromechanical Systems: MEMS Synthesis,
Microfabrication, Analysis, and Optimization
Sergey Edward Lyshevski ..................................................................................................... 15-1
Introduction
•
MEMS Motion Microdevice Classifier and Structural Synthesis
•
MEMS
Fabrication
•
MEMS Electromagnetic Fundamentals and Modeling
•
MEMS
Mathematical Models
•
Control of MEMS
•
Conclusions
16 The Physical Basis of Analogies in Physical System Models
Neville Hogan and Peter C. Breedveld ................................................................................. 16-1
Introduction
•
History
•
The Force-Current Analogy: Across and Through Variables
•
Maxwell’s Force-Voltage Analogy: Effort and Flow Variables
•
A Thermodynamic Basis
for Analogies
•
Graphical Representations
•
Concluding Remarks
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7-1
7
Modeling Electro-
mechanical Systems
7.1 Introduction .................................................................... 7-1
7.2 Models for Electromechanical Systems ......................... 7-2
7.3 Rigid Body Models ......................................................... 7-2
Kinematics of Rigid Bodies
•
Constraints and Generalized
Coordinates
•
Kinematic versus Dynamic Problems
7.4 Basic Equations of Dynamics of Rigid Bodies .............. 7-4
Newton–Euler Equation
•
Multibody Dynamics
7.5 Simple Dynamic Models ................................................ 7-6
Compound Pendulum
•
Gyroscopic Motions
7.6 Elastic System Modeling ................................................. 7-8
Piezoelastic Beam
7.7 Electromagnetic Forces ................................................. 7-10
7.8 Dynamic Principles for Electric
and Magnetic Circuits .................................................. 7-14
Lagrange’s Equations of Motion for Electromechanical Systems
7.9 Earnshaw’s Theorem and Electromechanical
Stability .......................................................................... 7-18
References ................................................................................ 7-19
7.1 Introduction
Mechatronics describes the integration of mechanical, electromagnetic, and computer elements to produce
devices and systems that monitor and control machine and structural systems. Examples include familiar
consumer machines such as VCRs, automatic cameras, automobile air bags, and cruise control devices. A
distinguishing feature of modern mechatronic devices compared to earlier controlled machines is the
miniaturization of electronic information processing equipment. Increasingly computer and electronic
sensors and actuators can be embedded in the structures and machines. This has led to the need for
integration of mechanical and electrical design. This is true not only for sensing and signal processing but
also for actuator design. In human size devices, more powerful magnetic materials and superconductors
have led to the replacement of hydraulic and pneumatic actuators with servo motors, linear motors, and
other electromagnetic actuators. At the material scale and in microelectromechanical systems (MEMSs),
electric charge force actuators, piezoelectric actuators, and ferroelectric actuators have made great strides.
While the materials used in electromechanical design are often new, the basic dynamic principles of
Newton and Maxwell still apply. In spatially extended systems one must solve continuum problems using
the theory of elasticity and the partial differential equations of electromagnetic field theory. For many
applications, however, it is sufficient to use lumped parameter modeling based on (i) rigid body dynamics
Francis C. Moon
Cornell University
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