Nine months ago I posted about a project we were working on to make some of the stuff we use in stores a bit smarter and more communicative. Things were going pretty well: we’d built a Proof of Concept device, based on an Arduino micro controller, and got a few people excited about the possible applications. But then we learnt a hard lesson concerning the difference between a Proof of Concept and a prototype, a pain which I shall attempt to convey in the following paragraphs.
Most people use the terms Proof of Concept (PoC) and prototype interchangeably, but in truth they are very different things. The PoC demonstrates that something is physically possible to do in its broadest sense. With a PoC, the little details can be put aside. Worried about battery life? No problem, attach it to wall socket. Heat problems? No drama, put a fan over it. Two weeks to build and test each unit – fine, it’s just a proof of concept. Conversely, the prototype demonstrates exactly how it will be implemented in an operationally viable way that won’t bankrupt the company. Battery life – how are we going to monitor it? How does it get recharged? Will it last long enough between charges? Is it easy to find the socket to plug it into? Can it be recycled?
The first challenge we faced when moving to a prototype stage was how could we make the electronics come in at a reasonable price point. It’s worth noting that, in our naivety, we thought we could pass the PoC to an electronics company and get back a complete solution. However, we found the costs were prohibitively expensive, so we were back to doing it ourselves. But this was a good thing because we made a rather marvellous discovery: it’s possible to get a small run of printed circuit boards manufactured for under £100. So using some free software, called DesignSpark, we were able to build a nice circuit board that we could assemble in a couple of hours. How cool is that? The second discovery we made was that the expensive, and rather unwieldy, Arduino could be replaced by a much smaller and cheaper ‘Pro’ version. So a couple of revisions later, we had a very robust and economically viable ‘brain’ for our device.
Our second challenge was which sensors to use. Our Proof of Concept detected changes in state using magnetic switches. Unfortunately, this would have meant installing powerful magnets to the equipment that would be used with it: a big no-no as far as economics and health and safety were concerned! Micro switches were too hard to mount, optical switches didn’t work reliably and laser range finders seemed a bit like overkill. Fortunately we discovered some infrared proximity sensors that could be used. These are fairly useful, and some are supplied with a big rely such that they could be used to control mains voltage. Not for this project, but worth keeping in mind.
We still have a few challenges to overcome, but I think we’re on the final strait. Hopefully in my final instalment I’ll be able to give the ‘big reveal’ and say what it is that we’ve actually been working on.