David Thomson is a
keen Android user and MOTODEV member, who explores off-road areas by
trail bike every chance he gets. David rides an
Austrian-made KTM 640 Adventure - a bike with enough power to take you
off the edge of one map sheet, clear across to another.
When you explore the wilderness, it's handy to have a GPS
unit that shows and logs your location on a map. The cheapest GPS
is still more expensive than the GPS that you already have in your
smartphone. With this in mind, David's project was born -
build a mount to hold and power his Motorola DROID phone on his
motorcycle.
Before starting the project, David wondered about
the vibration tolerance of the phone. So, in the true spirit of
science, he did some vibration measurements, first on a car (for which
phone mounts are available, so we know phones can tolerate that level of
vibration). And then on a motorbike, to see how far it was
from the car spec. He used an Android App called "vibration
meter" to compare frequency and amplitude between the motorcycle
mount and the Motorola car mount (suction cup to windshield). Vibration meter is a free app in the Android market.
The car mount gave a vibration reading in the 5's on the Mercalli scale
(~3.5 Richter), while the motorcycle was in the 6's (~4.5
Richter). That is a tenfold increase in wave amplitude between
bike and car! So a vibration-damping motorbike mount looks like a
serious problem. David solved most of the problem by using an
off-the-shelf enclosure for the phone. He choose the Aqua Box
from RAM Mounts. This is the transparent-lidded box in the
picture below. It comes complete with base mounting
hardware, that was drilled and screwed onto the bike's instrument
console.
The completed phone mount on David's motorcycle
All that was needed now was a USB connection, to charge the phone from the bike. David used an off the shelf micro USB cable to bring USB into the aqua box and then the phone. The USB cable was made by 3BRPowersports, who fabricated a custom cable with a 2-pin Molex connector on the end, to plug it into an unused connector under the bike's dashboard. The voltage comes out of the stator at a nominal 12V, that actually varies depending on the engine's RPM. Much less than this reaches the USB power cable, as the bike's draw is significant. The cable maker has a voltage regulator in the cable that only allows USB-spec power through; this was carefully tested before connecting the phone!
David used the old "trick" of a fridge magnet to trigger the phone’s “Car Dock” mode to switch to using big buttons on the Droid screen. The phone tracks and displays his location while he moves. He uses the free OruxMaps App to acquire the maps and store them, so a (costly) data connection is not needed at "run" time. This is an excellent and ingenious "hack" in the best sense of the word. There's a longer account by David here.
Do you have a story similar to the one described above? What out-of-the-box ideas have you had for personalizing your phone for your own needs?
Let us know by leaving a comment below or post on our Facebook wall at: www.facebook.com/motodev
By Nicole McMorran (Social Media Manager) and Peter van der Linden (Android Technology Evangelist)
