Hey,

for a long time now It thought i would be cool to do some nerd stuff to my bike and make cycling to school (12 km enough time to think about stuff like that) a bit more interesting.
Finally our teachers in school came up with something called a subject connecting work. So we toked our chance and signed us up for physics and computer science, to program our own GPS powered bicycle computer.
It tooked us about one week beside school to set the whole thing up and we finished it around two weeks ago. It suddenly came to my mind, that I could post some images in here. Maybe somebody else is thinking about doing something similar or already did and find this interesting.

Technically we're using an N810 Tablet you could describe as the heart of the system. Our software is written in Java and runs Jalimo.
To calculate speed we're using my bikes dynamo which is integrated in my front wheel. Maybe you know these dynamos, they're really cool because they aren't producing any friction lost what makes their impulses the perfect thing to calculate the speed and distance from.
The problem of how to get the number of these impulses we solved by putting an LED on it and let a Light sensor in combination with a LEGO NXT count the impulses and transmit them via bluetooth to our tablet.
Basicly that's it is. Sounds simple but produces a lot of trouble if you try to.
But the thing we were really interested in was the GPS Feature to protocol where we've been and let us analyze every second of our ride.

But let the pictures talk:



















Beside the Mobile part on the Tablet we wrote an Desktop application to analyze the log files you can see in this slideshow, powered by open street maps. This gives you the chance to see how fast you went, which mountains you climbed or which acclivity you went through and it downloads the right data of your location directly from the web.


I'm really interested which mark we'll get for this. The best thing in my eyes was when we showed it to our Physics teacher and he said we shouldn't put all our rights and techniques away and we answered synchronous "too late it's already GPL" .

toti

So... you have a version of Java that runs on the tablet? :-)

Yea, he said he is running Jalimo, aka software java (not hardware acc.)

Anyway, that is really cool. But why do you use the NTX? Just to make it simpler with more accuracy?

If you just want basic speed, can't you use
, with the GPS data, to find speed, even basic acc.?

So you have a bluetooth program that can talk to the NTX, is it using standard API's? Can you release it? Or is it tied into your program?

I my school would allow us to build things like this.

You can actually get speed straight from gpsd, but there are arguments for recording wheel rotation: it allows you some instrumentation (speed) when you can't get a fix, and you can even extrapolate from last known position and velocity (e.g. under a bridge), and it's also easier than integrating path length for an odometer.

Like Thesandlord said it's running on jalimo in combination with SWT for the graphical Interface.

Properly it would be much easier to calculate the speed from the given gps data but we wanted the whole thing to be really geek like and there are some more Physical aspects on this side, perfect to make our Physics teacher satisfied so we decided to use the NXT.
We're thinking about continuing the development on the project and releasing a version where you can choose between low geek mode which is using the GPS for all calculations and is thereby independent from any hardware and the High geek modus where you can connect your Tablet to an AVR Board or an LEGO NXT to calculate the speed from the data given by the dynamo.

Talking to the NXT does honestly look much more spectacular than it really is. There is a project called lejos which is providing an API called Icommand to communicate with an NXT from your computer via Bluetooth. You can use it in the same way on your tablet, you only need to recompile the runtime libraries for ARM. You can also use the standard Linux Bluez API but in this case it's also necessary to compile some libraries.

toti

Man - that sure beats the playing cards I used in the 1950's to geek my bike!

Very very cool.. /Here is anouther bluetooth bike computer that should adapt to your software.
http://www.soundofmotion.com/
I think you should put this up on maemo garage. I'm sure it will be worth some major Karma points.