|
Re: Using antiderivative to find velocity from acceleration
Practical applications note:
Your standard 3-axis accelerometer is going to be reading something like 9.8 m/s^2 in some direction while apparently at rest. This is usually a good thing. A reading of less than this generally means your robot is rapidly approaching the ground, or we're all in a heap of trouble, as gravity has taken a holiday.
Nevertheless, your robot isn't actually accelerating at this speed towards the ground, so you need to subtract the acceleration of gravity from the reading of your accelerometer. Which is all fine and easy, until your robot starts pointing in a different direction and gravity is suddenly -9.8 m/s^2 in the x direction.
This means you need to keep track of your robot's orientation in space, just so you can accurately account for the effect of gravity. Which means you slap a 3 axis gyro on your robot and start integrating rates of rotation to determine your orientation, to determine where gravity is, to subtract gravity from your overall acceleration, which you finally integrate to determine your velocity.
And then you wrap it in shiny white plastic, call it a Wii MotionPlus, and make millions of dollars.
Heaven help you if the accelerometer is off-center of the axis of rotation, though. Then you get all sorts of fun extra motion.
__________________
The difficult we do today; the impossible we do tomorrow. Miracles by appointment only.
Lone Star Regional Troubleshooter
Last edited by Kevin Sevcik : 06-04-2010 at 22:18.
|