IMU

An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the magnetic field surrounding the body, using a combination of accelerometers and gyroscopes, sometimes also magnetometers. Essentially, an IMU allows you to figure out where something is and how fast it is moving, generally through the use of accelerometers and gyroscopes.

The IMU we are using is the 6 Degrees of Freedom ±2000°/sec ±16g IMU - ITG3200/ADXL345, made by SparkFun Electronics. It is a small breakout board containing both the ADXL345 accelerometer and the ITG3200 gyroscope, which can be communicated with via I2C.

The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g. Sample code can be found here, and it is important to note that in order to convert the output provided there to m/s², you must first multiply it by 0.004 (the resolution) and 9.80665F (the universal gravitation constant). (e.g. xAcceleration_in_m/s2 = (double) xAccl * 0.004 * 9.80665F)

The ITG3200 is a single chip, digital output, 3-axis gyroscope. Sample code can be found here, and output is given in °/s.

Useful Links:

• Documentation for the IMU