SparkFun Forums

[dsfernandes]

Hi!,

I need to keep track of the position of a blimp flying inside a closed environment, mounted on which there is an Arduino and some other sensors, but can't figure out a solution (I am fairly inexperienced with eletronics).

I have tried to use an accelerometer for this, since, according to some sites (like this one and this one), it is possible, even though highly innacurate. I'm using an ADXL320 for the task, but the readings I get from it won't change when i move the it (it does change when I change the IC's inclination relative to the earth's surface, as expected). I think this is because the acceleration on a moving blimp is way too small.

I've also considered a GPS shield for the Arduino, but I don't think that would work since the blimp will be flying in a closed environment. Also, the blimp is small, so there are severe restrictions on the weight of the components.

What are my options for keeping track of position of a flying object?

Thank you!

[fll-freak]

Are we to assume that a "closed environment" is indoors?

If so, you can forget GPS. an IMU is only good for a short duration unless you have another sensor system (like GPS) that can reset it. People have tried RF propagation system with some success. Searching the forum here will find a dozen similar threads.

Can you have one or more external beacons to help?

[Tenyu]

Sounds like an interesting project!

What plane of movement are you attempting to track though? If you're trying to track its position along the surface of the ground, you may want to consider a digital compass.

http://www.sparkfun.com/products/7915

Using a compass would probably only work if the velocity of the airship was both known and constant.

If... the speed is variable, you can't determine the speed, you need more than just the xy(ground) tracking, this project could get very difficult.

Good luck!

[wsc]

On the blimp I would have a couple IR LEDs and a small speaker capable of making a loud chirp. Flash the IR LEDs and make a chirp at the same time. If you know the speed of sound, and you can tell how much time passes between the IR flash and the chirp being detected at a base station, then you know how far away the blimp is.

If you need to know where the blimp is, not just how far away it is, then you need 3 base stations, and to triangulate the calculated distance from each base station.

If a base station hears a chirp but doesn't see a flash, then it was an echo.

It may not work in practice but in theory, it is possible.... IMHO anyway.