Simple, inexpensive, accurate calibration of 9 axis Inertial Motion Unit

Absolute orientation estimation is crucial for navigation of robots, drones, unmanned vehicles. It is also needed in bio-metrics, virtual reality, human robot interaction systems and in devices like cell phone, smart watch etc. Nine axis MEMS inertial motion unit(hereafter called IMU) consisting of accelerometer, gyroscope and magnetometer is used widely to obtain absolute orientation. Sensor fusion is used to combine the readings of the individual sensors to obtain correct estimate of the absolute orientation. However MEMS devices are noisy and correct calibration is needed for the sensor fusion to work. Existing libraries on nine axis sensor fusion fail to give accurate drift free orientation estimate as they either don’t use accurate calibration algorithms or don’t prescribe a way to collect good calibration data. Also it is difficult and time consuming for a hobbyist or a researcher working on bio-metrics or SLAM to implement complex calibration algorithms or to design good calibration rigs. We propose a new calibration setup which consists of some easy to implement calibration algorithms along with a new calibration rig. Our calibration framework attains better accuracy and drift free estimate of absolute orientation than the current state of art libraries.