Servo - January 2016

Mind / Iron

by Bryan Bergeron, Editor ª

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ERVO FOR THE ROBOT INNOVATOR

6 SERVO 01.2016

One of the benefits of open source microcontrollers and other hardware is that with a modest investment in a software package such as EagleCAD, it’s a simple matter to create custom boards to fit the size and weight requirements of your robot. For example, let’s say you’re working on a pint-sized quadcopter drone and every bit of extra circuit board not only cuts down on battery time, but requires a larger enclosure. If you’re working with, say, an Arduino Uno, then you can leave off the USB connector and create a round instead of rectangular board to better fit your quad design.

Custom has a cost, however. The first is, well, cost — in dollars and cents. You can probably pick up a standard Arduino Uno for less than

$30, including shipping. A custom Arduino — in comparison — can easily run $30 for shipping alone because of the multiple vendors involved in supplying parts. There is the board manufacturing cost, as well as the cost of the components to populate the board. There’s also the cost in the time and effort required to design the board, order the components, wait a week or two for everything to arrive, and then spend a day assembling and testing the board.

Perhaps the greatest cost in going custom is the cost of keeping up. It seems as though the microcontroller companies are announcing new boards on a quarterly basis. They’re faster, more powerful, and sometimes even cheaper. Fortunately, they tend to keep the same physical footprint and connectors. So, upgrading your robot to the latest board is a 10 minute board swap. Not so with a custom board — especially if every component

The Cost of Custom

Dear SERVO:

Bryan Bergeron’s November 2015 editorial where he compared the work of experimentalists and engineers reminded me of the investigation of the Challenger Shuttle disaster. While the investigation went on and on and everyone was pointing fingers at each other, it took Nobel prize winner, Richard Feynman to shut them all up with one little experiment he did in front of the media. He took a piece of the rubber like that of the seal of the propellant tanks, immersed it in ice water, then showed how the rubber would shrink and harden under similar conditions that existed on launch day. Just like the experimentalist that dunked the PCB into water to see its effects! Sometimes the guys with the degrees — unlike Feynman — get too wrapped up in their ego and look for the solution that validates why they are engineers. (I am both, by the way.)