GPS-INS-BARO hybrid navigation system taking into account ground effect for autonomous unmanned helicopter

Abstract

Autonomous unmanned helicopters are useful in disaster response activities, but their reliability needs improvement to broaden its application area. GPS-INS hybrid navigation systems using Kalman Filter have been used to improve the reliability of autonomous unmanned helicopters, but they are not robust against the absence of GPS measurements. The vertical accuracy of GPS measurement is less than horizontal ones. The vertical channel of INS is unstable. Adding the altitude sensor to GPS-INS hybrid navigation system is expected to increase the accuracy and improve reliability. Barometric altimeter is not so accurate, but it is widely used because of its convenience. For unmanned helicopters, though, it is known that the barometer altitude deviate downward from the actual altitude, where the helicopter is close to the ground. This phenomena is due to the ground effect. This paper describes the method to build GPS-INS-BARO hybrid navigation system, which takes into account the ground effect for the autonomous unmanned helicopter. We adopted a centralized approach to integrate different sensors with asynchronous measurement updates. The parameter sets for successful estimation were shown using numerical simulation results.