/* This value is scaled in a weird way. It's a running total of accelerometer
* readings minus the ground accelerometer reading. That means it measures
* velocity, and quite accurately too. As it gets updated 100 times a second,
/* This value is scaled in a weird way. It's a running total of accelerometer
* readings minus the ground accelerometer reading. That means it measures
* velocity, and quite accurately too. As it gets updated 100 times a second,