lecture 07 mechatronic design concepts

Spring 2002 Mechatronic Design; Lecture 1 1

MECHATRONIC DESIGNConcepts

Abdülkadir Erden, Prof. Dr.

Mechanical Engineering Department, METU

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

[email protected]


mailto:[email protected]


Abdülkadir Erden, Prof. Dr.

Mechanical Engineering Department, METU


[email protected]

Multidisciplinary


mailto:[email protected]


Typical configuration of a mechatronic machine

Sensor

Actuator

Information processing

Mechatronic Machine

Environment

(Physical world)


Sensor

Actuator

Information processing

Mechatronic Machine

Environment

(Physical world)

multidisciplinary system


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


• SystemSystem: Flying robot.– OrgansOrgans: Hover, Cruise, Stability, ...

• ModulesModules: Fan speed sensor, Speed control,..– ElementsElements: Fan, speed sensor, ...


• SystemSystem– OrgansOrgans– OrgansOrgans– ......

• ModulesModules• ModulesModules• ......

– ElementsElements

– ElementsElements

– ......


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 ModelsThe 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 structureEstablishment 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 1992aA 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.


S1 S2 S3

S11 S12

S111 S121

S1211 S1212

S21 S22 S23

S211 S221 S222 S231

S2211 S2212 S2311

S31 S32

S321

S3211

Overall Function of the

Mechatronic Machine, f


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 model to mechatronic design problems.


Network modelDevelopment 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.



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,

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.


Clean Dishes

Load/Unload Dishes

Wash Dishes

Dry Dishes

Take water-in

Heat water Bring water to propeller

Rotate propeller

Take detergent

Take water-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.



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, electrical and computer engineers can equally incorporate their own processes.

2. This model needs to be a tool that guides and assists a mechatronic design team (team leader and team members).

3. 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.

4. Processes within the network have to be modeled by functional approaches independent of the physical realization of the corresponding functions.

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

lecture 07 mechatronic design concepts

Business

mechatronic design lecture

design architecture

architectural design

design informationtogether

design cost

themechatronic design

designarchitecture design

redundant design