Anurag is an engeneering student who loves skating. He has integrated a DIY speedometer to his skates.
An Arduino counts the number of wheel spins in order to calculate the speed of the skater. The problem is that the wheels are not always in contact with the ground, and slow down when in the air. To solve it, he integrated an ultrasonic transmitter to measure the distance between the skate and the ground, so that the speed measures can be taken at the right time. The interface can also calculate humidity and temperature...
Thanks to Anthony Prieur