Design and implementation of an Attitude and Heading Reference System (AHRS)

This paper deals with the development and implementation of a cheap Micro Attitude and Heading Reference System (AHRS) using low-cost inertial and magnetic sensors. The orientation is parameterized with unit quaternion and the data fusion is done unifying a quaternion linear formulation of Wahba´s problem with a Multiplicative Extended Kalman Filter. It includes the gyro bias model. The estimation methodology proposed in this work is implemented and evaluated in real time, in order to assess its effectiveness. Special attention was paid to the low power consumption, speed and weight requirements, leading to the selection of a 16-bit microcontroller. The sensor suite is based on a tri-axis accelerometer, a dual axis gyro, a single axis gyro and a tri-axis magnetometer. Furthermore, the system is equipped with a Bluetooth module, which provides wireless capabilities. The total system supply voltage is 3.3 V. The dimension and weight are 60×40×15 mm and 60 g, respectively. The attitude rate estimation is 55.5 Hz.