Fuel Gauge/Sensor?

[scdwyer]

I was wondering if anyone had ever implemented a fuel level sensor on their UAV. If so, how did you do it? I would like to be able to have some warning on when fuel runs low.

I have thought about building either an optical or capacitance based sensor, but if someone has done it already, some hints would be nice.

Thanks

[clolson]

My best idea so far has been to put black marker lines on the back of the fuel tank and point a camera at it. But I'm a software guy ...

[robe_uk]

This might be best in the electroincs section,

found this post using search function, may be a start if not to solution

http://www.rcgroups.com/forums/showthread.php?p=3551655&highlight=fuel+gauge#post3551655

Rob

[scdwyer]

Excellent, thanks. That helped a bunch.

[kd7ost]

I tried it once using a darkened box (shielded from ambient light) and shooting a coded IR beam through the tank at a given level. The problem was that the Fuel I used didn't block IR radiation so it would detect if I broke the beam with my finger, but not if the fuel was there. It went right through. I then figured that since my gas mix was green, that it would be better to use a green LED in the box and a CDS photo detector on the other side. The current to the LED could be adjusted to tune the luminous intensity. Lower than 20 ma. The amount of resistance in the photocell would change as the fuel level dropped and allowed the green light to hit the sensor. I didn't remake the box to fit the CDS sensor though. I would think that would be a good, and non intrusive way to go.

Dan

[jtprouty]

I set up a capacitive system that used measured the level of the gasoline based on the difference in capacitance of air (dialectric) and fuel (conductor). Resistance in the system changed as the fuel level changed.

I used an analog to digital converter to convert the signal for input into autopilot and display on the ground station. Static testing was succesful but I left the company before I could do any flight testing. I'll see if I can dig up the schematic for the sensor if there's any interest.

[Dragons_Fire]

if you check the nuts and volts from a few months back, they had a doggy dish that used capacitance to measure water level.. the only problem would be to change it so it measures more than just empty /full.