The what, why and how of mechatronics

The what, why and how of mechatronics by D. A. Bradley

This article provides an introduction to the basic concepts ofmechatronics. It considers the impact of mechatronics on the process ofproduct design and development and sets out ajamework within which the underlying technical and organisational requirements associated with a mechatronic approach to system design and development can be successfully deployed.

n recent years mechatronics has had a significant and increasing impact upon engineering and engineering education as a defining approach to I the design, development and operation of a wide

range and variety of complex engineering systems generally characterised in their operation by a high degree of integration between electronic engineering, mechanical engineering, information technology and software. It is however important to note that the mechatronics concept is not just about achieving technological integration but, as suggested by Fig. 1, involves aspects of organisation, training arid rnanage- iiieiit and therefore, while emphasising the integration at the systems level of the core technologies, has much in common with a concurrent engineering approach to product development'.

Mechatronics does, however, face a particular problem in that the breadth of approach, which is one of its greatest strengths, is also a major weakness in that the term has been, and indeed is, used in association with, or referring to, a wide range and variety of engineering systems from machine tools and manufacturing systems to consumer goods and domestic appliances. The result is that the significance and likely impact ofthe adoption of a mechatronic philosophy by a company or organisation has often been neglected, misinterpreted and misunderstood and the possible benefits thereby rejected or ignored.

As a consequence of t h s wide interpretation, no agreed definition of mechatronics has emerged, further compounding the problem. Indeed, it often seems that there are as many definitions or attempts at definitions

problem definition

MECHATRONICS

industrial design

aesthetics

Fig. 1 A framework for mechatronics

ENGINEERING SCIENCE AND EDUCATION JOURNAL APRIL 1997

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Fig. 2 The evolution of mechatronics

information

\ technology

mechanical electromechanical + mechanisation + systems _.t mechatronics

electrical f electronics f technology

as thcrc are claimed practitioners! Typical of the definitions that have been produced

is that of the EEC/IRDAC Working Party on Mechatronics which states that:

‘Mechatronics is the synergetic combination of precision mechanical engineering, electronic control and systems thinlung in the design of products and proce~ses.’~

An alternative definition reads:

‘Mechatronics represents an approach to the design of engineering systems which involves the integration of mechanical engineering, electrical and electronic engineering with software engineering and computer technology at all levels of the design pr~cess.’~

Though differing in form, both these definitions, along with the many others that have been produced, share common features in that they emphasise a holistic approach to the achievement of integration at the systenis level as well as the importance of cngineering design. It is therefore important that mechatronics is fioin the very beginning considered not as a separate engineering discipline but instead as an integrating,

world v

environmental interactions

Fig. 3 A generalised mechatronic system

systems level approach to the design and operation of a wide range of complex engineering products and processes. Thus:

‘By definition then, mechatronics is not a subject, science or technology ~ P Y cr-it is instead to be regarded as a phdosophy-a fundamental way of lookmg at and doing things, and by its very nature requires a umfied approach to its deli~ery.’~

Ths article is therefore intended to provide an introduction to the basic concepts of mechatromcs, to consider its impact on the process ofproduct design and development and to outhne a framework wthin which the underlying techmcal and organisational requirements associated with a mechatronic approach to system design and development can be successfully deployed.

The what of mechatronics

Prior to the introduction of the microprocessor, the major engineering dsciphnes had tended to become increasingly independent, with each seehng solutions wthm their own particular domain The advent of the rmcroprocessor and the associated growth in micro- electromcs technologies has seen a reversal of this trend towards separation to one of increasing integration, as suggested by Fig 25 It is the resulting ‘transfer of complexlty’ fiom the mechanical doman into electromcs and software that is associated with the introduction of local processing power in the form of the mcroprocessor and its derivatives that can therefore be considered as the major drivlng force in the development of mechatronics The result is complex, integrated systems whch offer great levels of performance per unit of cost than their largely mechanical predecessors

Consider now the representation of the generahsed mechatromc system shown in Fig 3 in which the system is separated into an energetic domain and an information domam Communication with other systems and subsystems is achieved through the medium of the world interface, which allows the system to receive and transrmt data The relationshps between individual mechatronic systems or subsystems


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Drives Film advance Film rewind Shutter Focusing Zoom Flash interface Aperture Flash setting

Shutter speed Aperture Zoom Mechanical coupling

tow1 processor Flash settcng

Expopsure data

L

Sensors Film speed Film counter Focus Exposure Zoom Lens attachment Flash attachment Body closure

Local processor Focusing drive Aperture control

Lens interface Lens type Focus Aperture Zoom Mechanical coupling

User interface Program select Aperture Shutter speed Overrides

within the context of their individual worlds is of importance in understanding the nature of mechatronics, since such systems can often be viewed at a number of different levels, each of which may well constitute an independent niechatronic system, as may be seen froin the following examples.

An automatic, autofocus camera is shown in schematic form in Fig. 4. At the level of the human user the camera may be seen and understood as a mechatronic system in its own right, with in this case the world interface being the user interface by which the selection and setting of the system operating parameters is carried out. However, each of the individual subsystems shown in the figure-body, lens and flashgun-are themselves niechatronic systems and could also be represented by Fig. 3 with, in the case of the lens and flashgun, the associated world being the camera body.

This interrelationship between mechatronic systems at differing levels of complexity is further illustrated by Fig. 5 for an automated manufacturing environment. Here, the highest level of the system, LEVEL 0, represents the factory as a whole and may be considered as a series of discrete 'islands of automation' connected by a broadband communication network. At the next level down, LEVEL 1, each of these islands of automation can be viewed as a mechatronic system made up of a series of

Fig. 4 An automatic, autofocus camera system

trolled (CNC) machine tools, robots and automated handling systems interconnected by an appropriate local-area network (LAN). The lowest level shown on the Figure, LEVEL 2, then represents an individual CNC inachine or robot together with its internal communication system, in which case each of the nodes is a particular subsystem, such as a joint, which again may well be mechatronic in form.

Both these examples also serve to illustrate a further feature of many niechatronic systems in that operation at the system level is in most instances transparent to the user. In the case of the camera this means that, following their choice of operating mode, a user is fiee to concentrate on the primary task, that of composing the picture, without the need to worry about the

Communications link

\ , Island of automation

rk CNC machine tool or robot

Individual CNC machine

Factory level system consisting of islands '

of automation connected by a

broadband network such as MAP

Island of automation consisting of CNC

machines and robots linked by a local-area

Internal communications

coniputer numerically con- Fig. 5 A mechatronics hierarchy within manufacturing


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Fig. 6 Product development strategies: ( a ) patterns of innovation in product development; ( b ) product range

Japan

Europe

time, years

a

competition competition

Europe

) Japan . - price and performance range

b

behaviour of the camera, which has now assumed responsibility for its own operation.

From the foregoing, mechatronic systems may in general be seen to be characterised by the following major features‘?

0 They are generally complex systems which e h b i t high levels of integration.

0 They demonstrate increased functionahty with respect to conventional systems.

0 Functionahty is transferred from the mechanical to the electronic and software domains.

0 They are based on the deployment of some form of real-time system architecture, often involving distributed and devolved intekgence.

0 They are generally based on a multiprogram structure involving user selection.

0 They generally tend to deploy a multisensor environment.

0 Operation at the system level is generally transparent to the user.

The why of mechatronics

Successful operation in a hghly competitive market demands that companies have the abhty:

0 to operate with reduced product development time- scales in order to capture market share

0 to respond rapidly to changes in competitors’ products to increase the competitiveness of their products by taking advantage of developments in technology

0 to provide increasing levels of performance and reliability at little or no real increase in price to the customer

e to plan for and to develop new market opportunities.

In Japan, meeting these requirements resulted in a reduction of product development times as part of

a pohcy of incremental development supporting a wide product range This strategy may be contrasted with what was untd relatively recently the more usual European and American model offewer but larger step changes in product development and a lirmted product range concentrated on specific market sectors, thus allowng sipficant gaps for penetration by competl- tors, as suggested by Fig. 67.

Though mechatromcs ofien supports and enables the development of new products and markets, such as the compact &sc player, which would not otherwise have been possible, it can also afford the opportunity to enhance the behaviour and performance of an emsting product h e whde respondmg to the introduction of a new product range by a competltor. Consider for instance the development by Canon of the EOS620 autofocus single-lens reflex camera following the introductlon by Minolta of their Alpha 7000 autofocus camera The introductlon of the Alpha 7000 had reduced Canon’s market share to around 20% By adopting from the outset a mechatronic approach to the design ofthe EOS620, Canon was able to place the drive for the autofocusing system in the lens rather than in the body, as was the case with the Minolta The result was that its market share recovered to around 30% over a period of 3 years7 *.

The effect of mechatromcs as a driver of the product development process in order to satisfy an increasingly demandmg and sophsticated market is perhaps most strongly seen in the automotive industry, where vehicle systems have become increasingly more mechatronic in nature with features such as engine management systems, traction control, arbags and anti-lock brahng now common place9-” Indeed, reference to Fig 7 suggests that future vehicles wdl see further mechatromc developments, with ‘drive-by-wire’ steering, colhion-avoidance systems, lane traclng and navigatlon control becormng increasingly avadable, first as options and then as standard features.

The motlvation of a move by a company towards the


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adoption of the mechatronics concept must therefore be that of providmg the company with a strategic and commercial advantage, either by supporting the creation of new and novel products, by enhancing the performance or manufacture of an existing product, by gaining access to new and developing markets or by some combination of these factors. In particular the company must be able to provide satisfactory answers to the following questions:

Are the principles and features associated with a mechatronic approach to product design and development valid for the range of products and markets under consideration? Are such principles and features of themselves a significant means of gaining a competitive advantage?

If the answer to these questions is yes, then it is likely that the company will benefit from the adoption of a product development strategy based on mechatronic concepts and principles.

Mechatvonics and education Over the past few years there has been a significant

growth internationally in the provision of postgraduate, undergraduate and other mechatronic courses. These courses are generally characterised both by their academic level and content and by the economic environment and culture withm which they exist. Thus in Europe there is a tendency to place the emphasis within the course on the design aspects of mechatronics, whereas in parts of South-East Asia the concentration is perhaps more on the mechatronic aspects of manufacturing technology. In each case, however, the aim is to produce engineers and technicians who are capable of adopting a mechatronic outlook and who can then fit into and support the needs and requirements of the local engineering culture.

The time avadable for courses, whether at postgraduate, degree or dlploma level, is however constrained and it is therefore neither possible nor

practicable to compress existing degree or dploma courses in electronics, mechanical engineering, computer systems and information technology into a single course in the available time-scales. This means that a degree of selectivity is required in constructing a mechatronics course at whatever level'*. It is also important that, in addition to their technical and technological base, mechatronics courses provide the necessary insight into the integrating aspects of mechatronics. It is not therefore simply sufficient to select a combination of courses from existing courses offered by specialist departments and call the resulting combination a mechatronics course. While such speciahst courses may well form a bignificant proportion of a mechatronics course, they must be placed in context and integrated with other, more specifically mechatronic, material. Thus a typical mechatronics course may supplement speciahst courses in areas such as software engineering or drive technologies with courses on design methods and systems engineeringI3.

In the case of postgraduate courses, the need is generally to produce a broadening of the students' experience into other areas of engineering and design rather than a deepening of their knowledge in a relatively narrow field. Given the wide range of student backgrounds on such courses there is therefore a need for a flexible structure which enables the students to gain experience in new areas of engineering and related technologies while providmg the integration required.

As has already been hinted, the most challenging aspect of any mechatronics course is that of demon- strating integration and transfer of complexity and of allowing students to experiment with different approaches to the solution of problems. In many, indeed probably in the majority, of mechatronics courses at whatever level, this is achieved through some form of group project work involving students typically worlung in groups of 4 to 6. Much larger groups have, however, been used successfully, particularly at KTH in Stockholm, where, over several years, groups of 15 to 20 students &om the mechatronics course have worked on a range of industry-based proje~ts'~.

envirhmental control

collision avoidance

4-wheel steering active Suspension

Fig. 7 The mechatronic car


85

Fig. 8 Relationships between the mechatronics technologies

Mechanical engineering

Electronics

Software

Spatial relationships Motion in three dimensions Forces Structure

Signal processing Information transfer Communications

Abstract

By using appropriate constraints, projects can be particularly effective in the early part of a course in introducing students to the basic concepts of mechatronics. As the course progresses, constraints can be progressively removed and more complex problems introduced. Further, by involving industry in the project and by requiring the group to manage its own budget, to develop cost models for production, to adopt formal project planning procedures and so forth, a more realistic ‘feel’ can be given to the project, to the benefit of all participants, including the tutors. Examples of typical projects include the design of a novel drive and control system for top-loadmg washmg machines for the US market, the development of a manufacturing facility for small-to-medium-scale electronics production and the design of a guided bus system for city use.

The how of mechatronics

The achevement of a successful mechatronic design

Algorithms Manipulation of data Logic

environment is largely concerned with three factors:

0 communication 0 collaboration 0 integration.

Communication The essentially separate development of the major

engineering disciplines prior to the advent of the microprocessor, and hence of mechatronics, meant that they developed their own particular ways of thinking about, t ahng about and defining their own perceived problem space. This has been further compounded by the way in which each of the major mechatronics disciplines tended to think about themselves. In order of increasing abstraction as outlined in Fig. 8, mechanical engineering focused on spatial relationships and the associated forces and motions in three- dimensional space while electronics became involved with signal processing, information transfer and communications,

Fig. 9 The communication gap

Physical

and software engineering became associated with the manipulation of algorithms, data processing and logic.

Though the picture of the relationship between the major mechatronics technologies as presented above is grossly oversimplified, the resulting effects are nevertheless very real, with significant communication problems, as suggested by Fig. 9, existing between engineers from different disciplines. Indeed, the same problem can be interpreted by engineers from different backgrounds in such distinctly different ways that to an outsider it would seem that they are each considering dfferent problems, which indeed to some degree they are as each individual or group tends to concentrate on analysing the problem in relation to their own area of specialism and expertise.

A major role of the mechatronics engineer is often therefore to act to


86

bridge such communication gaps that may exist between the specialist members of the design team, in order that each understands their particular responsibilities and role within the overall product design and development process, and hence to ensure that an effective environment for the exchange and development of ideas is created”.

Collaboration and integration The primary objective of

any company is that of maintaining, developing and improving its competitive

ft

Fig. 10 The ‘over the wall’ approach to technology transfer

- position in the market-place; hence to be effective the adoption of a mechatronic approach to product design and development requires the collaboration of all members of an integrated product development team towards that common goal. This means the removal of internal competition and of the traditional barriers between design and production, eliminating the ‘over the wall approach’ of Fig. 10 to technology transfer, and the adoption of a completely open and frank product development culture within the companyI6.

Mechatronics and concurifeent engineering The achievement of the goals of communication,

collaboration and integration implies that mechatronics must be closely linked to concurrent engineering in the management and organisation of the design process. Indeed, it could be said that although concurrent engineering can be applied to areas of engineering other than mechatronics. it is not perhaps possible to be truly mechatronic in approach without adopting the precepts of concurrent engineering and weighting factors such as design for manufacture, testability, quality and serviceability equally with the performance and technological aspects of mechatronics design. The effect is to bring forward and highlight factors such as changes to the manufacturing, test and support procedures required to accommodate a new or novel design as well as help to identify features that will increase competitive- ness1’J8.

Like mechatronics. con-

current engineering aims to integrate expertise from all disciplines, both technical and non-technical, during the product design phase, with trade-offs regarding manufacturability, testability and serviceability being made in real time. Though these areas may be relatively small in terms of overall project cost, decisions made during the design process often have a high leverage, and the right decisions made at the right time therefore have a significant impact on overall life-cycle costs, as illustrated by Tables 1 and 219.

Organisational strategies for mechatronics design include:

Project-centred ouganisation: This creates a relatively self- contained group by the secondment of individuals from speciahst functional groupings on a temporary basis, as suggested by Fig. 11. An organisation of this form supports a greater focus on and attention to the individual project while informal co-ordmation, which requires less organisational effort, serves to achieve and support interaction.

Matrix organisation: The matrix organisation of Fig. 12 combines lateral co-ordmation with a more conventional vertical command structure to avoid duplication of resources. Within the matrix organisation, the project team is made up of indwiduals from the individual specialist groups under the control of a project leader or manager responsible for co-ordinating

Table 1: Product development costs (after Reference 19)

Conceptual design 3-5 40-60

Design embodiment 5-8 60-80

Testing 8-1 0 80-90

Process plannihg 10-1 5 90-95

Production 15-1 00 95-1 00

Table 2: The cost of design changes (after Reference 19)

Time change is made Relative cost

During design

During testing

During process planning

During pilot production

1

10

100

1000

the project. These indwiduals still, however, retain membership of their specialist groupings, allowing their experience and knowledge to be made more widely available. A matrix organisation is suited to the co-ordination of effort on large and complex projects as well as to projects requiring different people for each phase of the project.

Conclusions

Many current products and systems depend for their success on the adoption of a mechatronic approach to engineering design and


87

product development. To be truly mechatronic it is not however enough simply to consider the technical and technological aspects of the design but it is also necessary to adopt an integrated approach to product development such

organisation

as that represented by concurrent or simultaneous engineering. In particular, it is essentd that the design process should ensure that it is aimed at ‘doing the right thing’, because then it is possible to ‘do things right’; it is in achieving these goals that mechatronics . has its part to play‘”.

In education, mechatronics courses provide a means by whch industry can be provided with indwiduals with the skdls to enable them to function in a

Fig. ,* Matrix organisation

mechatronic environment and it is therefore no surprise to see that graduates &om such courses often find themselves moving rapidly into positions of responsibility as the link between more specialist groupings.

References

1 COMERFORD, R. : ‘Mecha.. .what?’, IEEE Spectrum,

2 REITDIJK, J. A.: ‘Ten propositions on mechatronics’, Mechatronic Syst. Eng., 1990, 1, (l), pp.9-10

3 BRADLEY, D. A.: ‘Product design and development- why mechatronics?’. Drives, Motors and Control Conf., NEC, UK, October 1991, pp.2-1 to 2-5

4 MILLBANK, J.: ‘Mecha-what’, UK Mechatronics Fontm Newsletter, Summer 1993

5 KAJITANI, M.: ‘A concept of mechatronics’, J Robot. Mechatronics, 1989, 1, (l), pp.8-13

6 BRADLEY, D. A., BRADSHAW, A., SEWARD, D. w1, and MARGRAVE, E: ‘Mechatronics and intehgent systems’. 2nd Intl. Conf. on Intelligent Systems Engineer- ing, Hamburg-Harburg, September 1994, pp.395-400

August 1994, pp.46-49

Pro ect-centred

Fig. 11 Product-centred organisation

7 BUUR, J.: ‘Mechatronics design in Japan: a study of Japanese design methods and working practices’ (Institute for Engineering Design, Technical University of Denmark, 1989)

8 BRADLEY, D. A., DAWSON, D., BURD, N. C., and LOADER, A. L.: ‘Mechatronics: electronics in products and processes’ (Chapman 81 Hall, 1991)

9 HUIJSING, J. H.: ‘Integrated smart sensors’, Sens. Actuators

10 ZABLER, E., HEINTZ, E, DIETZ, R., and GERLACH, G.: ‘Mechatronic sensors in integrated vehicle architecture’, Sem. Actuators A, 1992, (31), pp.35-45

11 OLBRICH, T., BRADLEY, D. A., and RICHARDSON, A. M. D.: ‘Built-in self-test intelligent microsystems as a contributor to system quality and performance’, Qual. Eng,,

12 WILLGOSS, R. M.: ‘The teaching of mechatronic engineering: the use of matrix methods’. Mechatronics ’96/M2VIP, Guimares, September 1996, 1, pp.333-338

13 TOMKINSON, D., and HORNE, J.: ‘Mechatronics engineering’ (McGraw-Hill, 1996)

14 Personal communication 15 BELBIN, R . M.: ‘Management teams: why they succeed

or fail’ (Heinemann, 1981) 16 ANDREASEN, M., and HEIN, L.: ‘Integrated product

development’ (IFS Publications, 1985) 17 CARTER, D. E., and BAKER, B. S.: ‘Concurrent

engineering: the product development environment for the 1990s’ (Addison-Wesley, 1992)

18 HARTLEY, J. R.: ‘Concurrent engineering: shortening lead times, raising quality and lowering costs’ (Productivity Press, 1992)

19 WOODRUFF, D., and PHILLIPS, S.: ‘A smarter way to manufacture’, Business Week, 30th April 1990, pp.6469

20 EUREKA: ‘Design for manufacture: guide for improving the manufacturability of industrial products’ (Institute for Product Development, Technical University of Denmark, 1994)

A, 1992, (30), pp.167-174

1996, 8, (4), pp.601-613

0 IEE: 1997

Professor David Bradley is with the School of Electronic Engineering and Computer Systems, University of Wales, Dean Street, Bangor, Gwynedd LL57 lUT, UK. He is an IEE Member.


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The what, why and how of mechatronics

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