GASTO DEL GOBIERNO

This chapter introduces the main base theory of this thesis in the dimension of engineering design and product development. The main models and concepts are briefly explained here, including the model of transformation system, Theory of

Properties, complete model of the origination and operation phases of technical systems, utilisation of models and prototypes in product design and development. Domain Theory and Theory of Dispositions are off-springs of theory of technical systems. They are also key theories of this thesis. These theories and models are utilised in Section 7.

The Theory of Technical Systems (TTS) is a comprehensive and unifying theory to promote the understanding of technical systems, and building a foundation for a rational approach to the engineering design process (Hubka & Eder, 1988). The abstract forms of modelling of transformation systems, a generalized life cycle and classes of properties of systems constitute the major parts of TTS (Eder, 2008).

Transformation system is the fundamental model in the TTS. In Figure 55 is an application of the transformation system to the design process. The transfor- mation system model incorporates elements of system theory. It explains the role of technology in society, and the elements of a socio-technical system model. All transformation systems have a certain purpose, i.e. fulfilling stated needs by trans- formation of an operand (materials, energy, and information). The elements of a transformation system are connected by suitable relationships, and the properties of the whole system result from the sum of the elements, whereas the system’s behaviour includes the synergistic effect of the relationships. The structure of the system is formed by the arrangements and relationships of the elements. The system is connected to its environment by means of inputs and outputs. The major elements of the total transformation system are divided into a process, an oper- and, and the operators that drive and guide the process. The operand may be affected by modifying its structure, form, location, and time. The Theory of Tech- nical Systems originates in the late 1960s. The base model in Figure 55, published in (Hubka & Eder, 1988) has been further developed over the decades so that, for instance, assisting inputs and outputs have been added to the model (Eder 2008).

One of the purposes of engineering design is to provide information about suit- able real transformation systems that are capable of fulfilling needs, i.e. changing an operand from starting state to final state. On the other hand, in our case, we can look at the design process itself as a transformation process. In this view, the object to be designed is the operand of the design process. Designers are the human operators with their characteristics, working methods, and use of infor- mation. Working means (tools) are the technical systems of a design process. Operations of the process have a certain sequence and structure, components and relationships, systematic and procedural aspects (methods), creativity and intuitive factors. The information system and management and goal system are the context in which engineering design takes place. The social, moral and politi- cal context is the environment of designing, producing and using the resulting technical system. Design is the transformation from a more abstract form of model of a technical system or process to a more concrete form. Each step or stage of this transformation may be performed with the help of suitable methods, and indi- vidual designers may prefer a different set of methods. Some new computer- based methods and tools, such as virtual environments, have penetrated into

engineering practice to only a limited extent. The sum of actions in designing, and the sum of recommendations for methods that can be used, is termed Design Methodology, a heuristic prescription (and model) of “how to proceed”. The devel- opment of Design Methodology aims at general methods and methodologies that are not product-specific, and that are also suitable for new product development. (Hubka & Eder, 1988)

Theory of Properties. In this research, the Theory of Properties (Hubka & Eder, 1988) is an essential sub-theory of the TTS. Every technical system, its elements and relationships have certain properties that describe the system. Many of these properties are objectively measurable, while others can only be assessed by subjective means. The state of the technical system (TS) at any one time is defined by the totality of all its properties and their state of embodiment. The most important property of any TS is its function reflected in the system behaviour. Customers or users determine the desired properties for TS in the form of a re- quirements specification, which is then transformed into a design specification that guides the design of the system. The properties can be categorized (Figure 13) by way of observing them:

External properties interest the users, operators, and customers. The ex- ternal properties are the relationships of the technical system to its envi- ronment. For instance, ergonomic properties deal with direct relationships between humans and technical systems

Internal properties deal with relationships between the elements of the sys- tem and the properties of those elements.

Design properties serve as a means for the designer to create the desired external properties. These properties are usually hidden from the system users.

DESIGN PROPERTIES Structure Function Organ Component Tolerance Delivery Deadline Form Dimensions Surface Manufacturing Methods Materials Manufacturing Properties INTERNAL PROPERTIES Corrosion Resistance Durability Strength EXTERNAL PROPERTIES THE TECHNICAL SYSTEM

Delivery & Planning Properties Distribution Properties Aesthetic Properties Ergonomic Properties Operational Properties Functionally Determined Properties Function Liquidation Properties Economic Properties Manufacturing Properties Law Conformance Properties Laws Regulations Standards Codes of Practice Quality Operational Costs Price Wastes Re-cycling Function Reliability Space Requirements Durability Life Weight / Mass Maintenance Operation Surface Quality Color Appearance Storage Space Transportability Packing

Figure 13. Relationships between classes of product properties (Hubka & Eder, 1988).

Complete model of the origination and operation phases of technical sys- tems. Technical systems are generally very complicated, as is the progress from the first idea to the finally realized system. In order to design the system properly, it is important to recognize all the phases that a technical system must pass through during its origination and operation, and all the factors that will influence the TS. The complete model of the whole TS lifecycle can be divided into four major phases, including a number of partial processes: origination, distribution, operation and liquidation (Hubka & Eder, 1988). The complete applied model of the origination and operation phases of technical systems can be seen in Figure 56. The model is an early representation of product lifecycle thinking.

Each technical system attains a series of typical states of existence and com- position of the transformation system during its lifecycle. The design engineer should be capable of using mental models, i.e. imaging a proposed system in all of these states in order to examine the suitability of the system for the requirements in each state. This activity could be supported by modelling and testing (Hubka & Eder, 1988). Mental models by individual designers seldom cover all aspects of the lifecycle, and they are difficult to communicate for other people.

Utilization of models in the Theory of Technical Systems. The properties of proposed TS must be determined in order to evaluate against the requirements. Different methods for evaluation can be applied depending on the life phase of the system. In a conceptual phase, modelling and simulation are often the most suitable means of evaluation. A model is a representation of the real technical system, the process, or the idea by suitable means (Figure 14). Laws of similarity deal with the relationships between a model and the original system (Hubka & Eder, 1988). They emphasize the purpose of the model, and which properties are, therefore, to be expressed in the model. Apart from determining the properties of the system, mod- els can be used for e.g. verifying, communicating, or instructing. Typically, a proto- type of a TS permits the determination of most of the properties relevant to the final system, whereas a model often only permits the determination of certain properties, such as behaviour, structure or form. Aspects of the models can be summarized (Hubka & Eder, 1988):

Context ranges from abstract to concrete, from material to conceptual, from general to specific

Function and purpose can be one or a combination of the following: de- scribing, predicting, exploring, planning, prescribing

Medium: can be one or a combination of: verbal, mathematical/symbolic, imaginal/graphical

Model of usage: can be iconic, similitic or analogue, metaphoric

M&GS

Env : Space, Time TrS

feedback

TS

Hu IS

Transformation Process TrP Od2

Od1

Executio n System

Physical Reality

Transformation System or P hysical Model

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Env : Space, Time TrS

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Od1 Executio n System Mental Model Operand Desired End State Designing, Planning, Realizing, Concretizing, Predicting EMPIRICAL 1:n DOCUMENTATION m Perceiving, Abstracting, Theorizing, Generalizing ABSTRACTIVE DOCUMENTATION Operand Observed State OR possible Starting State Operand Actual Output State Operand Actual Input State Time y Time x

Figure 14. Formation and use of models. Mental models are formed by abstractive documentation, by perceiving and abstracting from physical reality, and their properties are elaborated by generalizing and theorizing. The relationships of similarity between two systems are investigated by the laws of similarity. (Hubka & Eder, 1988)

A model is a way of representing knowledge for the purpose of thinking, communi- cation, decision making, system design or analysis and operation ranging from mental images to highly refined mathematical equations (Sheridan, 2014). There- fore, something can be modelled to the extent that it can be understood by hu- mans. In science, a distinction must be made between denotative and connotative models (Sheridan, 2014). Denotation refers to the explicit literal meaning of the words, symbols or signs used to represent the model, while connotation refers to the implied or suggested meaning – a metaphor.

Prototyping and virtual prototyping. In their book Product Design and Devel- opment, (Ulrich & Eppinger, 2004) define the term ‘prototype’ as “an approxima- tion of the product along one or more dimensions of interest”. Therefore, any entity exhibiting at least one aspect (i.e. product property in the terminology of Hubka and Eder) of the product that is of interest to the development team can be viewed as a prototype. This definition includes such diverse forms of prototypes as con- cept sketches, mathematical models and fully functional preproduction versions of the product. Prototyping is the process of developing such an approximation of the product (Ulrich & Eppinger, 2004) including the dimensions: a) Physical vs. analyt- ical, b) Comprehensive vs. focused. Within a product development project, proto- types are used for four purposes: learning, communication, integration, and as milestones (Ulrich & Eppinger, 2004). Product development is a process consist- ing of cycles that include the steps of synthesis, analysis, determining individual deviations, overall evaluation (Weber & Husung, 2011).

Figure 15 shows where prototyping belongs in the Theory of Technical Systems of Hubka and Eder (1988). A concept of design review is related to prototyping, and this phase of system originations as well. The design review should be con- ducted by a group of experts when most properties of the system have been spec- ified, before the detailing and manufacture of a prototype. For a quantity-produced system, the prototype is usually the first physical realization.

Task preparation TS designing Work preparations for prototype Manufacture of prototype Testing prototype, developing Re-designing, corrections Work preparations for

quantity production Manufacture of ”zero-batch” Testing ”zero-batch” Corrections to TS Corrections to means of production Quantity production Distribution Working process

Figure 15. Simplified block diagram of the origination and operation phases of TS in quantity manufacture (Hubka & Eder, 1988). Not all feedback loops are shown in the diagram.

By building and testing the prototype, all manufacturing properties including as- sembly should be evaluated and verified. All errors and difficulties found should be fed back to the designers in order to develop the systems and correct the manu- facturing documents. Without careful prior design work, this phase can lead to a costly re-design mode. After the prototyping phase, a “zero-batch” is manufac- tured. This phase incorporates all the preparations for actual production, including manual work and organizational aspects. Virtual prototyping should naturally be related to the above-described ‘conventional’ prototyping process.

The theory of Dispositions. The Theory of Dispositions of Olesen (1992) deals with relationships between the parameters of a product and the parameters of the systems which are realising the product and which the product meets during its life. The theory was proposed to be used during the design process in order to anticipate those parameter relationships and to choose the optimal parameters of the product during its production and product life. The dispositional mechanism of the theory describes an important type of integration between the various func- tional departments of a company (Figure 16). A disposition is the type of effect which arises when the product and, for example, assembly system are affected at the same time. Dispositions can be measured in terms of their effects on the so- called universal virtues: cost, throughput time, quality, efficiency, flexibility, risk, and environment.

Figure 16. General model of disposition between two functional areas (Olesen, 1992). In disposition a decision taken in one functional area, i.e. product design, consists of two parts: a data part describing the task (typically represented by drawings), and a dispositional part describing the conditions affecting activities in other functional areas, such as product assembly.

Olesen (1992) proposed so-called Design for X (DFX) tools as one possible means for “revealing dispositional effects by exposing the solutions’ characteris- tics, and the relationships between design characteristics for the product and the X-system”. The DFX tool can be used either for analysing an existing product and X-system in order to identify dispositions, or for choosing design characteristics in order to achieve desired dispositional effects. Matrix-based product modelling methods (the product modelling Design Structure Matrix, P-DSM) can support the development of complex products by, for example, visualizing, structuring and analysing them (Malmqvist, 2002). Matrix-based methods can be classified ac- cording to scope and content, e.g. as inter-domain or intra-domain matrices.

Domain Theory. The Domain Theory was introduced in the doctoral disserta- tion (in Danish) of Andreasen (1980). It approaches the product synthesis from the viewpoint of four domains: transformation, function, organ, part. In each domain, design synthesis progresses through detailing and concretization. Each domain is a system in which the structural characteristics which define or specify the system, and its behavioural properties must be distinguished. Later, the “function domain” was abandoned. It was reasoned that each domain should contain a synthesis dimension, and in each domain it should be possible to reason backwards from demanded behaviour to structure (Andreasen, 2011). Thus, in the organ domain, the products effects, i.e. functions, are defined as structural characteristics. How- ever, in this thesis, the original Domain Theory with four domains is referred to because the Disposition Theory is based on that. Thus, we can avoid mismatch and confusion between these theories. The terminology of Andreasen in respect to distinguishing concepts of property and characteristics was adopted by Weber; see e.g. (Weber et al., 2003), (Weber & Husung, 2011) and putting it to a centre of his CPM/PDD (Characteristics-Properties Modelling, Property-Driven Develop- ment/Design) theory. This distinction reduced the external, internal and design

properties of Hubka’s Theory of Properties to two classes (Andreasen, 2011), while its “characteristics” are very similar to “internal properties” of (Hubka & Eder, 1988). The CPM/PDD theory has been used as basis for the development of com- puter-aided tools and methods as well as PDM/PLM systems (Weber et al., 2003), (Weber & Husung, 2011).

The paper by Andreasen (2011) gives a nice and comprehensive review of the elaboration of the “Copenhagen School” in the area of design theory and method- ology and product development that was based on the basic theory of Hubka and Eder.