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Ping through fan blade

Can you use an arduino sensor to ping through a fan blade to sense the outside world? This is for my sumo robot, which will have a full body length spinner. I already have an accelerometer attached if the ping sensor can not work =/

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I wanted to mention the sync'ed propeller thing! Arrgg!

You need an encoder, dude. You need a hall-effect sensor, a slot encoder, IR reflective sensor etc, so you can sense the exact position of the fan blades, or more to the point, one particular spot on the propeller where there is a space, and not a blade. You then simply fire your sonar when this "mark" comes around.

I suppose you should do the math on how far apart fan blades are, how fast they turn and the time it takes to fire a sonar unit. At far distances, it takes longer than you would thing to fire one of them.

Would photoresistors work for sensing the position? I could paint the spinner black... 

Receiving pulses back will be very hit and miss as the time from 'send' to 'receive' is dependant on distance, whereas the timing between blades will be fixed.  You can certainly use sychronisation for the 'send' pulse but have no way of guaranteeing getting a return pulse. 

You might consider pushing the robot off the ring rather than trying to disable it with a full body spinner, have a look at the rules for the sumo tournement you want to enter, most prohibit BattleBot style weapons.

Thanks for your responses! I will either stick with the accelerometer or see if I can get a sensor to ping out under the spinner, as it is not flush to the ground. Weapons have never been prohibited at this tournament, although I have a feeling that it will be next year ;) 


I will post this robot in a few weeks. As of now I am waiting on a new lipo (the other one was old and a cell puffed out during charging).

Looking forward to seeing your bot, not many sumos are violent ;)