Design and implementation of low cost integrated navigation system for mini autonomous helicopter

A low cost integrated navigation system based on cascaded coupled architecture was developed for mini autonomous helicopter. A novel linear attitude fusion algorithm was introduced to fuse gyros' output with accelerometers' gravity observation and magnetometers' magnetic observation, and the estimation errors were proven to be bounded. By considering the measurement delay of GPS, the velocity and position were estimated from previous attitude estimation, accelerometer measurement and delayed GPS measurement using two cascaded complementary filters. Finally the terrain clearance was derived from ultra sonic ranger finder and vertical velocity estimation by method combined of outlier rejection and reset. The experimental results have shown that the flight state estimations from the proposed navigation system possess excellent static accuracy and dynamic performance, and can fully meet the requirements of mini autonomous helicopter.