Position estimation system with UWB, IMU and a distance sensor for quad-rotors

In order to estimate the position of a quad-rotor in GPS-denied environment such as under bridges, we developed a position estimation system using ultra-wide band (UWB), inertial measurement unit (IMU), and distance sensor for the quad-rotor. The accuracy of UWB is tens of centimeters and the UWB is several times better than traditional positioning systems based on WiFi, Bluetooth and GPS signals. In addition, a distance sensor is mounted to the quad-rotor to improve the estimation accuracy of the altitude. This paper presents experimented results using the quad-rotor equipped with the developed system in order to evaluate the estimation accuracy. The experimental results show that an altitude accuracy of 0.03 m can be achieved.