Plotting Location w/ Accellerometer Project

[Greg McKaskle]

If you want to play with this, it may be worth checking to see if your laptop has an accelerometer in it. I know that my last Mac laptop did. It was used to park the hard drive before it landed during a fall.

If so, you can read that accelerometer in LV and play a bit.

I looked on the Apple app store and there are a number of free apps that let you see the accelerometer data and let see their interpretation of the data.

As for using this on the robot, the key cases to think about are the ones where the floor is uneven. Sitting still, the robot and its accelerometer are tilted. Gravity's 1g is no longer in the pure Z direction. It is imparting a force on the other axes. If your code doesn't calibrate and ignore this, it looks like the robot is constantly accelerating in the uphill direction. If you do calibrate it for that tilt, then drive the robot a foot and stop it again, the floor is likely tilted a new direction. Once again, sitting still, you will accelerate uphill.

It is an interesting problem, and accelerometers are certainly useful on the robot, but integrating them to identify speed or location without isolating them from the force of gravity is quite hard.

Greg McKaskle