Conceptual design synthesis is part of the conceptual phase of the design
process, which focuses on creating alternative, candidate solutions.
Conceptual design phase has the greatest influence on the cost and
characteristics of the final product; an excellent detailed design based on
a poor and inappropriate concept can never compensate for the
inadequacy of the concept. Conceptual design is difficult, which currently
relies on the designer’s intuition and experience to guide the process. A
major issue in conceptual design is that often not many alternative
candidate solutions are explored by the designer during the design
process. The major reasons for this are the tendency to delimit a design
problem area too narrowly and thus not being able to diversify the
possible set of design solutions, possible bias towards a limited set of ideas,
and time constraints. Many researchers recommended a thorough search
of the design space for developing a good solution; this requires
generation of a large solution space. Mechanical devices (mechanisms
and machines) have fascinated the mankind throughout recorded history.
Conceptual design synthesis of mechanical devices is difficult even for
humans, and is also difficult to completely automate. In a single state
design task, the relation between an input and output are fixed, but in a
multiple state design task, the relation is not fixed. Much of the current
research has been focused on supporting synthesis of single state devices,
in particular where the device has to convert an input motion into an
output motion. Synthesis of multiple state device is in contrast rather poorly understood and
supported. Complete automation is unlikely to be possible; developing support taking into
account the strength of computer and and human is important mechanical device is not adequate
the biggest source for understanding of this process, and for its subsequent support,
is human designers. The concept of state for a mechanical device is explained in
detail by analyzing the existing multiple state mechanical devices. An
operating state described by elemental functions (defined by efforts-
motions of input and output components) and their associated
Understanding and Supporting Conceptual Design Synthesis of Multiple State Mechanical
Devices
configurations and configuration changes. However, study of current
literature indicates that little has been known about the actual processes
carried out by designers in synthesizing multiple state devices. The main
objectives of this thesis, therefore, are as follows: (1) understand the
multiple state device design synthesis process carried out by designers,
and (2) develop methods for supporting synthesis of multiple state
mechanical devices to enhance the number of solution alternatives
generated. Empirical studies are conducted to understand how designers
currently carry out multiple state design tasks. Ten designers are given a
multiple state design task and asked to generate as many solutions as
possible. The designers are asked to think aloud while carrying out their
synthesis processes. All these synthesis processes are video recorded, and
analyzed to identify what activities are involved in the multiple state
design synthesis, what the inputs are to each activity, and what the
outcomes are from each activity. It has been found from these studies
that design fixation is quite common, and the majority of the designers
pursued developing a single solution to the given design task. A generic
descriptive model of the multiple state mechanical device design
synthesis process, explaining how this is carried by the designers, is
developed. Based on this model, a prescriptive model of multiple state
design synthesis process, explaining how the multiple state synthesis
process should be carried by designers in order to develop a large solution
space, is also developed. The prescriptive support, for synthesizing a large
solution space for a given multiple state design task, has been evaluated.
Eight engineering designers participated in the evaluation procedure,
where each designer had to synthesize solutions for two, given multiple
state design tasks. Results indicate that use of the prescriptive support,
even without the power of a computational implementation, may have
been beneficial in helping designers develop feasible solutions in a
greater number of cases in a more efficient manner (that is, by
considering fewer solution proposals and in similar amounts of time). All the
designers who participated in this exercise gave a positive feedback
regarding the prescriptive support. However, in none of the design sessions
did the designers develop more than one feasible solution. This, along with
various other comments from designers, indicates that a faster and more
proactive support – implemented on computer – might be more useful in
supporting the tasks. The various aspects for a potential computer support
are discussed.
| Identifer | oai:union.ndltd.org:IISc/oai:etd.ncsi.iisc.ernet.in:2005/2463 |
| Date | 07 1900 |
| Creators | Todeti, Somasekhara Rao |
| Contributors | Chakrabarti, Amaresh |
| Source Sets | India Institute of Science |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Relation | G25496 |
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