Lecture 07 mechatronic design concepts

MECHATRONIC DESIGN
Concepts

Abdülkadir Erden, Prof. Dr.
Mechanical Engineering Department, METU

http://design.me.metu.edu.tr/aerden
erden@metu.edu.tr

Spring 2002 Mechatronic Design; Lecture 1 1

Multidisciplinary

Abdülkadir Erden, Prof. Dr.
Mechanical Engineering Department, METU

http://design.me.metu.edu.tr/aerden
erden@metu.edu.tr


Typical configuration of a mechatronic machine

Sensor

Environment
Information
(Physical world) processing

Actuator

Mechatronic Machine


multidisciplinary system

Sensor

Environment
Information
(Physical world) processing

Actuator

Mechatronic Machine


Abstraction & Modularization

• The main idea of abstraction is that we
leave out details and concentrate on the
essentials.

• Modularization is setting up components
into Larger units and each describe
structure in terms of these units.


An example


Architecture in Design & Architect

ARCHITECTURE in DESIGN
• Architecture;
• The art or science of constructing edifices for human use,
• The action or process of building,
• Structure,
• A special method or style of structure and ornamentation,
• Construction generally.

ARCHITECT;
• A master-builder, specially one whose profession is to
prepare plans of edifices and exercise a general
superintendence over their erection,
• One who designs and frames any complex structure,
• One who so plans and constructs, as to achieve a desired
result.


ARCHITECTURE in DESIGN

• Architecture design is most often associated with the early stages of stating the
functional specifications. Architecture design is desirable in mechatronics
because it enables the designers to isolate themselves from the details of the
eventual implementation technologies. The modules in the architecture should be
abstract enough so that they can be described in terms of function without getting
involved with the technologies. The appropriate time for consideration of the
various technologies is the implementation stage.

• Architectural design enables the mechatronics engineer to abstract away from the
large variety of technologies available and enables the initial design effort to be
concentrated on producing a correct functional specification.

• Architectures are just descriptions, or views, of systems. It is good practice to
formulate such a description during design because it facilitates conceptual
clarity, intelligibility, communication to others, and possibly provability.

• A structure is a set of parts and the relationships with each other. Both the parts
and relationships may be of many different kinds.

• Parts: sensors, motors, memories, transmission units, energy sources, etc.

• Relationships: spatial, temporal, control, communication.

Mechatronics

• Mechatronics is considered in its broader sense as the
name given to a special philosophy behind the design
and development of microprocessor-based products.
The reflection of mechatronics philosophy on the design
methodology of these products is defined as the
mechatronic design.

• Mechatronic design is mainly a product-oriented
approach and mechatronic philosophy should be applied
carefully particularly in the conceptual design phase of
the product development. This is because the functional
and geometric integration of "mechatronic organs" is
performed mostly during conceptual design.


• System(s)
– Organs
• Modules
– Elements


• System: Flying robot.
System
– Organs: Hover, Cruise, Stability, ...
Organs
• Modules: Fan speed sensor, Speed control,..
Modules
– Elements: Fan, speed sensor, ...
Elements


• System
– Organs
– Organs
– ...
• Modules
• Modules
• ...
– Elements
– Elements
– ...


A special methodology of mechatronic design is necessary because of the following reasons:

1- Designers with different engineering background in a design team
experience difficulty to describe and discuss their approaches at the
conceptual stage, without going into the details. This result in time loss in
product development and increase the design cost.

2- Engineering creativity requires availability of all the design information
together with possible solution principles. However, usually few designers are
involved in the creative stage of the design, hence many alternatives are
omitted because of the missing concepts, and/or poor communication among
the team members. Controversially, large number of designers in a team is
impractical and inefficient.

3- Technologically, it is difficult, if not impossible, to divide the design activities
into mechanical, electronics and software parts, and interfaces between the
three areas require special knowledge outside these engineering branches.

4- Overall design evaluation and verification are difficult until a very late stage
of the project. Hence, redundant design, or functionally over safe designs are
very common.


MECHANICAL DESIGN ARTIFACT MODELS

Design artifact (product) models are necessary to
extract functional and structural characteristics of the
engineering systems and/or machines.

They are developed independent of their specific
tasks.

They are necessary to design and understand
(reverse engineering) of complex systems.


MECHANICAL DESIGN ARTIFACT MODELS

Design artifact models existing in the literature are mainly
directed towards;

1. Physical or functional decomposition of the artifact to
be designed,

2. Representation of subsystems or subfunctions, which
are obtained as a result of the decomposition.

3. Modeling of the system behavior using these
representations.

Functional Decomposition In Design
Artifact Models
The functional decomposition can be defined as partitioning a given
complex functional design requirement into more manageable
functions such that it is easier to match design concepts with these
functions and arrive at a solution.
The functional decomposition is one of the most important steps in the
conceptual design. The designer feels himself/herself dealing with a
smaller design problem so as to concentrate on a special aspect of
the problem.
Steps;
1- Determination of subfunctions facilitating the subsequent search for
solutions,
2- Combination of these sub functions into a simple and unambiguous
function structure.
In an original design, neither subfunctions nor their relations are
generally known. Therefore, the establishment of an optimum
function structure constitutes one of the most important steps in
conceptual design for the original design problems.


Function structure
Establishment of function structure is directly related to the conversion
of energy, material and signal.

Conversion of Energy: Changing energy, transferring energy, storing
energy, and varying energy.

Conversion of Material: Changing matter, varying material dimensions,
connecting matter with energy, connecting matter with signal,
connecting materials of different type, channeling material, storing
material.

Conversion of Signal: Changing signals, varying signal magnitudes,
connecting signals with matter, connecting signals with signals,
channeling signals, storing signals.


BASIC FUNCTION EFFECTED
ITEM
Change Type

Vary Magnitude

Connect Number

Channel Place

Store Time


According to Ullman 1992a
A function can be described in terms of the logical flow of energy, material
and/or information.
Flow of Energy: The functions associated with the flow of energy can be
classified both by the type of energy and its action in the system.
Types of energy: Mechanical, electrical, fluid and thermal (for mechanical
systems).
Action of energy: Transformed, stored, transferred (conducted), dissipated,
supplied.
Flow of Materials
Through-Flow (Material Conserving Processes): Material is manipulated to
change its position or shape (position, lift, hold, support, move, translate,
rotate, and guide).
Diverging Flow: Dividing material into two or more bodies (disassemble,
separate).
Converging Flow: Assembling or joining materials.
Flow of Information: Flow of mechanical signals, electrical signals, and
software.

Benefits from the decomposition of the
overall function into subfunctions
1. Decomposition controls the search for solutions
to the design problem.

2. Division into finer functional details leads to a
better understanding of the design problem.

3. Breaking down the functions of the design may
lead to the realization of some existing
components that can provide some of the
functions.

The need for a special methodology of
mechatronic design;
1. Designers find it difficult to describe and discuss the way of
working on a total mechatronic system.

2. Choosing the right design concept in mechatronics is regarded as
very important, but the decision is often made early in the design
process with very few designers involved.

3. There are difficulties in dividing the design activities to mechanical,
electronics and software parts and in managing the interfaces
between the three areas.

4. The function of the total concept will not in general be verified until a
very late stage of the project.

Design methodologies of different fields are not sufficient
for mechatronic design because;

Machine design methodology has no means of abstractly describing
the logical relations between functions (i.e. when, in which sequence
and under which conditions the functions must be performed) since
these relations are built in a complex way into the physical structure
of the machine.
Electronic design methodology is mainly based on the analysis of 2-D
structures. There are neither tools nor traditions for formulating
alternative concept ideas.
Software design methodology is not capable of bridging the gap
between abstract functional descriptions, physical effects and
spatial relations, since such effects and relations do not exist in the
software domain.


A general hierarchical decomposition of mechatronic systems
include sensory (for environmental perception), cognitive (for
information processing) and motoric (for motion execution)
subsystems (Petrik, 1994). Apparently, there exist interfacing
elements between these sub systems and their components. The
importance of interfaces arises from the fact that, "mechatronic
organs" based on different technological principles should be
coupled together so as to achieve the total function of the system
successfully (Wingate and Preece, 1994). The current research in
the field of mechatronic design modeling is generally based on
developing function structures and representation of mechatronic
devices.


Functional Representation by Using
Functional Design Tree

Once a design need is identified with related design requirements,
the first step in an engineering design procedure is the functional
representation of a candidate system, which is able to satisfy the
given requirements. A systematic way for functional representation
of such a system is to establish a functional design tree, which is a
functional decomposition hierarchy that involves subfunctions of
systems at various levels of resolution and where the top most node
is to satisfy the required overall function. The overall function (F) of
a system (S) is represented in the most general form as follows;


Formulation

F(S) = {F1, F2, F3, .............., FN} where,

F(S): Overall function of the required system.
Fi: Subfunctions of the system at the first level of functional
decomposition (i = 1,2,3, ......, N).
N: Number of subfunctions at the first level of functional decomposition.

The functional decomposition of S can be represented in a hierarchical
tree structure which is called the Functional Design Tree (FDT) of
the system, S. Figure 5.1 illustrates the FDT of a hypothetical
system with 4 levels of functional decomposition.


Functional Cells (FC), Atomic Functional
Cells(AFC);
The concept of functional cells provides a way of symbolic
representation for the material, energy and information flow in a system
through the execution of sub functions. An important point to be noted
is that, functional cells at the first level of decomposition are
representational variables (symbols) at the highest level of abstraction.
As one proceeds to the lower levels of FDT, functional cells gain
precision in their definition due to lower functional resolution such that
at the leaves of the tree, AFCs are defined numerically or in a formula-
driven formal way representing precise subfunctions as precise
input/output mappings. This top-down approach results in a transition
from an abstract functional representation of the system to be designed
to a numerical representation. In the most abstract representation, the
only item in transition through the network is modeled as information,
while for the lower level resolutions, energy, specific material and
information items are explicitly described depending on the input-output
relations for AFCs.


Overall Function of the
Mechatronic Machine, f

S1 S2 S3

S11 S12 S21 S22 S23 S31 S32

S111 S121 S211 S221 S222 S231 S321

S1211 S1212 S2211 S2212 S2311 S3211


Petri-Net theory

Mechatronic systems are composed of various interrelated
components which are operating on different physical
principles and are integrated into a single system to satisfy
a design need. The main philosophy of mechatronic design
is to develop solutions to sub design problems at the
functional basis during the early design phases, particularly
at the conceptual design stage. The physical components
of a mechatronic system must be selected and integrated
such that they can communicate with each other to perform
these functions properly.

This course will focus on a design inference network model
based on the Petri-Net theory and application of this model30
Spring 2002 Mechatronic Design; Lecture 1

to mechatronic design problems.

Network model
Development of a framework to automate the conceptual
design stage of mechatronic design process is a recent
focus for researchers working on the theory of design. A
decentralized design inference network model is
developed for this purpose and will be used in this
course.
The reason behind using the network approach is that; in
mechatronic systems various interrelated components
based on different physical principles exist and have to
be integrated. This inherent decentralized characteristic
of mechatronic systems is modeled functionally through
a network architecture and the integration is achieved by
the information flow over the network processed at the
nodes.

A network architecture is used for such an automation
because;
1. Mechatronic functions/components are physically and
functionally decentralised. Their representations are
made available as the nodes of a network.
2. The information flowing over the network while being
processed at its nodes provides the formation of
integration through inference.


Need for the design models

A generic design model has to be generated so that the mechanical,
electrical and computer engineers can equally incorporate their own
processes.
This model needs to be a tool that guides and assists a mechatronic
design team (team leader and team members).
In order to develop this mechatronic design process model, reverse
engineering has to be applied such that, information flow between
various functions of mechatronic systems must be represented and
then the design procedure to realize this information flow must be
identified.
Processes within the network have to be modeled by functional
approaches independent of the physical realization of the
corresponding functions.

A communication model should be established between the nodes as a
support to the integration within mechatronic design inference.

A network architecture is used for such an
automation because;

1. Mechatronic functions/components are physically and
functionally decentralized. Their representations are
made available as the nodes of a network.

2. The information flowing over the network while being
processed at its nodes provides the formation of
integration through inference.


Several intermediate goals which have to be met in order to
achieve the objectives of this research are the following;
A generic design model has to be generated so that the mechanical,
processes.
This model needs to be a tool that guides and assists a mechatronic
In order to develop this mechatronic design process model, reverse
identified.
Processes within the network have to be modeled by functional
A communication model should be established between the nodes as a
support to the integration within mechatronic design inference.


Clean Dishes

Load/Unload Wash Dry Dishes
Dishes Dishes

Take water- Heat water Bring water Rotate Take Take water-
in to propeller propeller detergent out


automation of mechatronic design is required in order to;

1. develop a generic model of mechatronic design
process which can be applied equally to any
mechatronic sub system whether heavily
mechanical, electrical or computerised,

2. draw the virtual borders within the mechatronic
design and determine the characteristics of the
mechatronic design philosophy,

3. guide and assist a mechatronic design team with
a structured framework.

A network architecture is used for such an automation because;

1. Mechatronic functions/components are
physically and functionally decentralized.
Their representations are made available as
the nodes of a network.
2. The information flowing over the network
while being processed at its nodes provides
the formation of integration through
inference.


Several intermediate goals which have to be met in order to achieve
the objectives of this research are the following;
1. A generic design model has to be generated so that the mechanical,
processes.

2. This model needs to be a tool that guides and assists a mechatronic

3. In order to develop this mechatronic design process model, reverse
identified.

4. Processes within the network have to be modeled by functional

5. A communication model should be established between the nodes
as a support to the integration within mechatronic design inference. 46
Spring 2002 Mechatronic Design; Lecture 1

Lecture 07 mechatronic design concepts

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