Keyglove #08 – Orientation Demo from Jeff Rowberg on Vimeo.
NOTE: For the uber-eager, the actual rotation starts at the 1:00 mark. There’s some introductory explanation of what’s happening and the hardware in use that occurs on before that.
This video is a demo of the IMU algorithm results (a.k.a. sensor fusion) achieved with SparkFun’s 6DOF motion sensor board, which uses an ADXL345 digital 3-axis accelerometer and ITG-3200 digital 3-axis gyroscope. The readings from the board are raw from each device, and combined on the Teensy++’s MCU to create a quaternion representation of the orientation.
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The core of the Keyglove’s motion capture system is made up of a digital accelerometer and gyroscope. Both of these devices measure only one value—the accelerometer measures linear acceleration, while the gyroscope measures rotational velocity. This means that if the accelerometer is perfectly still and perfectly level, then it will experience only the force due to gravity (9.8 m/s2 downward), and if the gyroscope is held still in the same position, it will experience no measurable force at all. All of the math for dealing with velocity as it relates to position applies as well to gyroscopes and it does to accelerometers, but for the purpose of this post, I’ll focus only on the accelerometer.
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