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Co-evolution [DC01] refers to the (nearly) simultaneous development of (a) the understanding of a problem, and (b) the solution of the problem. A design problem cannot be fully defined in detail without making some design decisions along the way, thus requiring the interleaving of design tasks with tasks of problem analysis.

Example: Say your team is designing a tram. You are in charge of the instrument panel for the tram's driver. The position, kind, and size of the instruments (to name only a few of their characteristics) will depend on many other factors of the tram's design and its intended use. Some of these factors include: the size and age of the driver, the degree of infirmity or disability that a driver may have (e.g. can the driver be colour-blind?), the power plant of the tram, the number of doors of the tram, the regulations defining safety issues that must be accommodated, and the expected cost of the tram and of the instrument panel. All these factors involve making decisions that affect the tram design, and each must be grounded in other requirements for this problem.

You can't design the instrument panel without knowing its requirements, but its requirements depend in part on other designed aspects of the tram, which have their own requirements. So what comes first: requirements or design?

This apparent conundrum is solved by using co-evolution, a systems perspective, and a top-down approach to design.

One starts by considering the system as a whole: the tram is a “black box,” the internal structure of which is unknown. One defines requirements only for the tram as a whole. Then one designs a general solution only to the tram as a whole - setting overall dimensions, number of passengers, location of driver (right or left side); location of access points; nature of power plant; and related decisions. This sets certain constraints on the rest of the problem. In the process of designing this part of the tram, one generates a set of subsystems.

The next step is one of recursion. One studies the subsystems of the tram and generates requirements for them; this is the next step of the evolution of the problem. Each subsystem is treated as a black box. Then one designs solutions for those subsystems. This will lead to sub-subsystems.

One continues with this recursive process until one reaches the point of identifying specific physical parts.

This alternation between requirements generation and design is what we mean by co-evolution.

[DC01]. K. Dorst and N. Cross. 2001. Creativity in the design process: co-evolution of problem–solution. Design Studies, 22(5):425–437.
design/coevolution.txt · Last modified: 2020.03.12 13:30 (external edit)