We touched on scoping in our series about electronic product development, but it’s such a huge subject that it really deserves its own article.
Scoping is the very first phase of a project, the step where the idea or aspiration behind a device gets turned into a concrete set of features and processes. It is often overlooked by engineers because a lot of it takes place in meetings and discussions, partly mingled with commercial negotiations with clients. Nobody cuts any code or draws any circuit diagrams, so it doesn’t look like engineering. In reality, it may well be the most crucial step in the design process. It is desperately easy to sink a project right at the beginning by failing to scope it out properly.
We have a huge list of questions that we have asked clients over the years to scope out projects. We mentioned hidden assumptions in the previous article, but it bears repeating. You have to ask the “obvious” questions because they aren’t obvious to everybody. For example in one product there were a series of actuators that could be turned on or off depending on the prevailing conditions. What order should they be turned on or off in? After considerable discussion it became clear that this was a major piece of research in itself, and the code would need to be structured to make it easy to change that ordering.
One of the less obvious questions we ask is what the expected volume of sales is, and over what period of time. It makes a huge difference whether 200 or 200,000 devices are going to roll off the production line. The underlying question here is how much development effort (cost) is it worth putting into reducing the cost of each item produced. If you are only creating a small number of devices, it probably isn’t worth the effort of shaving a few pence off the overall costs. On the other hand, if you are producing high volumes of devices, it will probably be very economic to put that one-off effort into increasing the efficiency of the production line. Increasing automation and streamlining production tests, for example, will likely save you money in the long run. This is the sort of thing that affects design considerations surprisingly early in the process.
Another easily overlooked question is how the device is going to be powered. A simple coin cell will put different limits on the design to mains power, rechargeable batteries will need charging circuitry and so on. Power budgeting, electromagnetic noise and waste heat can all vary enormously depending on this decision.
We could produce more examples, but the basic point is this: the answers to these questions change the design. Radically, in some cases. You need to capture those answers before the design gets advanced enough that the changes will cost significantly, because once the design process is underway no change is completely free. TANSTAAFL, to quote Robert Heinlein: There Ain’t No Such Thing As A Free Lunch. Sometimes you change the product rather than the design, for example if it becomes clear that one feature is going to be very expensive to implement or another feature will do the job better. The earlier you find these things out, the less they will cost you.
The purpose of the scoping phase is to identify the requirements, potential costs and potential risks of a project. You cannot make sensible choices if you don’t know what the consequences of those choices will be. Obviously there are limits to how far you can take scoping before it becomes a significant cost itself — you have to start development at some point or you will never finish your project — but not asking enough of the right questions at the start of a project can lead to some nasty surprises.
We don’t claim to have a complete list of all the questions to ask to scope out a project. No one does. We learn with each project, often from the questions our clients ask us. You should never feel shy about asking consultants questions at this or any other stage of a project, because you may be revealing hidden assumptions of our own. The point is to ask and answer until everyone feels confident that they understand the implications of a project. Such a process is necessarily imperfect, and surprises may still arise, but good scoping dramatically reduces the chances of wasting money later on.