<aside> 🚩 A Design Concept is a general graphical and textual description of an intervention that is presumed to satisfy all requirements if properly refined and specified.

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Overview

Given a set of Requirements, one must search for interventions that satisfy them all.

You could use a “brute force” method: identify one design concept and work on it until you know whether it’s unsuitable. If it is unsuitable, discard and try again with another concept. Repeat until you find a suitable solution.

There are two show-stopping problems with applying a brute force method.

1. There are infinitely many unsuitable concepts. You will probably spend a great deal of time and resources - more time and resources than you probably have - trying to find a suitable one. The odds of successfully completing a design project on time and on budget dwindle rapidly.
2. If you stop at the first suitable solution, you’ll never know if you could have found something better. If you keep going to identify multiple suitable solutions - but can ultimately select only one - you will again waste tremendous amounts of time and resources. And settling for one or even a few suitable solutions reduce the odds of finding an interesting or innovative solution to nearly zero.

Using a brute force method is, therefore, intractable.

So designers will create several different design concepts. Each concept will be incomplete but will capture distinctive features. The designers will develop and refine them all gradually and in parallel as the design process continues.

Over time, the differences between concepts will become apparent. This will allow their fitness to be ranked with respect to the requirements. Some concepts will be replaced; others will be significantly modified to improve the degree to which they satisfy the requirements.

Eventually, the designers will be able to demonstrate that one concept is superior to the others. The designers will know with greater, but not absolute, certainty that they have found a good solution. That single concept then becomes the focus of further development.

A Design Concept Integrates Function Embodiments

A design concept must satisfy all the currently existing requirements (i.e., you don't want to under-design your concepts), and only the current existing requirements (i.e., you don't want to over-design your concepts). To do this, a designer must embody each function in a way that will (likely) satisfy the constraints on that function.

<aside> 💡 An embodiment is a physical principle or technology that provide a particular function and satisfies all its constraints.

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Say there is a requirement to lift up to 3,000 kg of people and cargo up to 13 m, inside a building. How many embodiments can you think of to meet this requirement?

• Cables lifting a platform from the top of the building.
• Hydraulically pushing the cargo up from below.
• Pneumatically pushing the cargo up from below.
• Motorized gears on the lifting structure that rides rack gearing in the support structure.
• Magnetic induction.
• Variable mass counterweights. (For instance, add ballast when the counterweight is at the top of travel to pull it down, and have the lifting structure rise; and remove ballast when the counterweight is at the bottom of travel to lift it up, and have the lifting structure drop.)

<aside> ❓ THOUGHT EXERCISE: Can you identify at least one advantage and one disadvantage of each of the embodiments given in the example, with respect to the stated goals?

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All these ideas are embodiments. Each embodiment represents a physical principle or technology that might be applicable to the problem. There is no reason to exclude odd or weird solutions when developing potential embodiments. However, one must exclude patently impossible ones, like anti-gravity and telekinesis.

When ideating embodiments, think about users and try to develop different embodiments that will accommodate the most diverse group of users. For instance:

• If you’re designing a human-powered vehicle, select different embodiments to ensure both men and women can use it; try to include embodiments that will accommodate people of atypical sizes and weights, and who may have back, neck, or arm weakness.
• If you’re designing a dishwasher, try to include embodiments for the control panel that will accommodate people with diminished vision and finger strength, as well as those who may not be able to bend over easily to put dirty dishes into it.

Each embodiment has advantages and disadvantages only relative to all the other embodiments necessary to satisfy all the requirements. In other words, two “good” embodiments may combine to make a “bad” concept.

<aside> 💡 A design concept is a set of embodiments that have been integrated together into a cohesive whole to provide all the functionality in the requirements, subject to the known constraints.

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• Example: conceptualizing a writing instrument.

<aside> 💡 NOTE ON THE FUNCTIONAL NATURE OF REQUIREMENTS The requirements in the example above are carefully phrased to avoid commitment to particular embodiments. We don’t write about the clip of a pen, but rather about its function relating to securing the pen for storage. This is because assuming there will be a clip is not rational. We must decide why there must be a clip first, before we specify that a clip is required. It is very important to challenge your assumptions always, even when they seem inevitable.

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