Fish trap model
From WikID
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This article is part of the Bachelor design guide; the original version can be found at page 43. |
The fish trap model is an approach for generating and developing a form concept for a product up to stage of the preliminary design (sketch design)[1]. As such, the approach is intended to cover the form-creation phase, or the conceptual design stage. The method is prescriptive, meaning that it prescribes how a process of concept development and form creation should take place. Visualisation techniques such as sketching and collages are an important part of the approach. The design alternatives and the criteria with which they are evaluated are created through subsequently sketching and collages. Generating design alternatives and creating and analysing collages for establishing criteria take place parallel and interactively.
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The basic design cycle of the fish trap model
The fish trap model is a systematic process of designing a product form. The model is systematic because it forces the designer to explore alternatives on three subsequent levels of increasing detail and meaning: topological level, typological level and morphological level. Exploring alternatives on each of these levels yields three types of concepts: a structural concept, a formal concept and a material concept. On each of these levels, large variations of design alternatives are generated and evaluated against a list of criteria. The criteria are derived from a visual exploration and analysis of the context. This exploration is done with the use of collages. Collages are appropriate tools to study a problem context visually. Particularly when defining the new product form collages should be analysed with stating the prototypical, behaviour-typical and solution-typical form characteristics. These statements should be made part of the list of requirements.
The fish trap model in the product design process
The fish trap model (see figure 1) starts at the stage of the design process when a basic structure of the functional components required for the primary function fulfilment is known. Compared to the Product Design Process, the starting point in the fish-trap model is a stage in between the function structure and the solution principle. The completed phase ends with the stage of material elsewhere called the sketch plan, layout design, or preliminary design.
The fish trap model in detail
In figure 4, the fish trap model is depicted in two ways; at the right, according to the normal representation of the process by phases, on left, through a diagram to visualise the divergence and convergence, and to indicate the occurrence of various solution types at each concept level. By divergence, solution variants are generated. Through categorising these variants in the converging subphase, the formation of concepts should occur. Key element of the fish trap model is its categorisation according to criteria derived from visualisations of the context, user group and usage. One or more concept representations are developed, indicated in the diagram as types. In the two following phases, this process is repeated at increasingly concrete levels. A simulation of the concept has to show which features can be expected. In comparing these expected features with the criteria originating in the visualisation of the product context, a choice can be made with which concept (type) the process is continued.
The structural concept
In the model, a basic structure defining the functional components needed for the primary function fulfilment makes up the beginning stage for the first phase. Functional components in general determine the construction and/or the functioning of a product. From hereon structural concepts are developed. Components allow different variants to be developed out of a solution principle. In the divergent stage there is a drive for a large quantity and variety in spatially composing the components, without judging their feasibility. In the convergent stage, the generated variants make up the starting point for conceptualising solution categories. By combining and substituting certain features of the different variants, we obtain an understanding of the possible topological solution types. Our technical knowledge starts playing a role in this type formation, because we need to think through the generated material in anticipating all kinds of consequences for a further materialisation.
To support the development of a structural concept, solution-typical categories can be distinguished. Through this categorisation, variants having a similar geometry will be presented as being thought of as a solution type; the solution types thus being developed from the type categories, are structural concepts. They represent directions to fulfil the primary function of the product intended regarding its principle solution. As the level of this design stage is rather abstract, it cannot be expected to make an exclusive choice for a particular concept. It thus implies that we must arrange the different concept types in order of suitability, to subsequently develop the most promising one up to the stage of a formal concept.
The formal concept
For generating roughly embodied variants, a wide range of possibilities are at our disposal in the form of primitives and their transformations. Through their surface ordering, these forms suggests, in principle, one or more classes for embodiment. It requires a general knowledge of the construction and manufacturing of parts, of connecting techniques, as well as the production volume, etc. It is useful to develop one or several less promising concepts as well. Finally, again various solution types with result for the fulfilment of the primary function representing different directions for embodiment. Assessing differences in their interaction is rendered a little easier than in the previous stage. In having more gestalt,we are more easily able to categorise them behaviour-typically to features of existing products. For evaluating this development level, we also have the verbalised criteria at our disposal that were derived from the collage.
The material concept
For the development of the material concept, one or several formal concepts serve as the starting point. This third step involves a further detailing of the overall materialised structure, for which the manufacturing aspect is consequently discussed in more detail. The model indicates this phase as running identical to the previous; so the generation of a preconcept stage here also precedes the working up of the material into a concept. Exploration still has importance for processing image material in order to think through a more detailed embodiment. Many variations can be thought up for a given concept through projecting the necessery technical knowledge and experience.
Categorising the variants in the converging subphase again requires a typological ordering thus offering the means to gain a structured insight into the generated variance. The morphological ordering elements can serve here as a guideline for categorising variants showing similarity with regard to form and material. This categorisation also needs to promote thinking through the technical aspects of the preconcept phase, drawing on more specific knowledge of materials, manufacturing, and assembly. A solution-typical categorisation offers a way to think through the technical aspects of a result, and the formation of behaviour-typical categories for thinking through its interaction in use. The application of colour will also play a role. The choice of materials and the manufacturing of product parts normally limits colour choices and the application of colour differences. The collage does not only provide information on the typicality of colours and materials desirable in the product context, but also about the ordering of these elements.
