A low-cost air data attitude heading reference system for the tourism airplane applications

A cheap tourism airplane ADAHRS unit is developed by fusing magnetometers, rate gyros and accelerometers (MEMS technology). The rigid body orientation is modeled with quaternion, which eliminates attitude estimation singularities. The real-time implementation is done unifying a quaternion formulation of Wahba's problem with a Multiplicative Extended Kalman Filter. It includes the gyro bias model. A quaternion measurement model is introduced. It avoids the linearization step that induces undesirable effects. Accelerometers detect gravitational acceleration and centrifugal forces, resulting in incorrect attitude estimation (e.g. false horizon and subjective vertical). Therefore, some pressure sensors are added, resulting in a robust solution. The real-time implementation uses a PCMCIA data acquisition card and a TabletPC. Simulated and real data validate the ADAHRS.