I've had the great pleasure of meeting Yaya several times, and her enthusiasm and skill never ceases to amaze me for someone so young. This is her latest project where she uses an NXT and standard sensors in a helment configuration, to control a wheelchair. Her video nicely steps through some of the issues she's had to contend with to get it all up and running.
She's entered it into the Melbourne University Engineering RoboGals competition so if you like it (or any of the other entries), feel free to stop by and vote (http://www.sciencechallenge.com.au/vote.html)
It is so encouraging to see students taking on projects that will ultimately go on to benefit society :)