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A move towards making human simulation tools to a greater extent 'designers tools' puts pressure on the tools to adapt to the way designers work, or indeed need to work in contemporary product development. This not only applies to human simulation tools but to CAD tools in general. Ullman (2002) discusses the implications associated with the development of 'the ideal mechanical engineering design support system' (however explicitly not incorporating design aids for ergonomics consideration in his discussion). Ullman argues that, although the evidence of CAD's ability to support the design process is evidenced by its wide use, CAD systems are weak in their ability to support many activities of the designer in product development. Design is more than making drawings; it is a complex human/computer undertaking, and, to date, the computer has only filled a very small segment of its potential (Ullman, 2002). Ullman believes that future

development of CAD systems needs to be driven from the 'D' and not from the 'C' in CAD, where the 'D' stands for design, or even more appropriately, stands for designer. This will require focused studies of human designers and their interactions with mechanical design support systems.

This is a complex subject area with many dimensions. One dimension is the call for enhanced functionality in CAD systems to support designers in collaborative working. One advance in that direction is the development of a real-time collaborative 3D CAD

system to enhance the usefulness of 3D CAD tools in team design projects, in both co- located and distributed situations (Nam and Wright, 2001). Another dimension is the call for CAD systems to better support designers at early conceptual stages, where it is important for the designer to be able to quickly sketch rough ideas in order to stimulate creativity and gain understanding, as well as to document and communicate ideas (Schütze et al., 2003). Commonly sketching is done on paper, as conventional CAD systems require complete, concrete and precise definitions of the geometry, which are only available at the end of the design process (Qin et al., 2003). An additional issue with CAD systems is the increased cognitive load that they impose when compared with sketching (Ullman, 2002). However, there are benefits from enabling sketching in CAD systems. One advantage is that it eases reuse of the sketches when developing the idea further in the CAD system, e.g. into 3D CAD models. Another benefit is that it facilitates the distribution of sketches and the receipt of quick feedback on the design from others involved in the development of the product, e.g. feedback via the Internet from

manufacturers situated on the other side of the world (Qin et al., 2003; Lim et al., 2004). There are many interesting dimensions of future CAD systems. However, in this thesis the discussion is directed towards the implications for computer based design support systems in the context of ergonomics.

Brennan and Fallon (1990) state that the process by which a designer arrives at a solution is not well understood, but methods used in the process include:

 A leap of the imagination (creative approach)

 Analogy with previously encountered solutions (pattern recognition)  Following a set of rules based on experience (heuristic approach)  Guessing (random search)

 Reducing the solution space to a finite number of possibilities and exploring each one in turn

 Transforming the design problem into a mathematical problem and obtaining a solution

Brennan and Fallon (1990) argue that computers excel in analysis and computation and may support or replace the human to some degree in some of the areas listed above. However, the human strengths are in pattern recognition and creative ability. Brennan and Fallon's view is that the human is a necessary component in the design process, and

automate. Baxter (1995) believes that creativity is one of the most mysterious of human abilities, and is at the heart of design, at all stages throughout the design process.

Norman (1994) shows how the relative strengths and weaknesses of humans and machines depends on the viewpoint taken (Table 4.1).

Table 4.1. Different views of characteristics of people and machines (Norman, 1994).

The human-centred view The machine-centred view

People Machines People Machines

Creative Dumb Vague Precise

Compliant Rigid Disorganised Orderly

Attentive to change Insensitive to change

Distractible Undistractible

Resourceful Unimaginative Emotional Unemotional

Decisions are flexible because they are based upon qualitative as well as quantitative assessment, modified by the special circumstances and context Decisions are consistent because they are based upon quantitative evaluation of numerically specified, context- free variables Illogical Logical

Hence it is important for design support systems to facilitate conditions for areas where human is seen as being superior to the computer (the machine) in the design process, e.g. in creativity. Ullman (2002) highlights that the ideal engineering design support system should support the management of different types of information and match the speed of the short-term memory during information development and add no cognitive burden while supporting information development. Hasdogan (1996) reports that, in the development of design methodologies, notably in CAD, it is often observed that in the early stages of design, designers need to retain in their mind the basic idea, making them impatient with any method that endangers their ability to maintain a grasp of their

original concept. Ullman (2002) argues that engineers/designers spend a great percentage of their time recreating prior work or looking for prior information, and one of the

greatest potentials for future design support systems is the ability to capture, archive and query the full range of design information.