Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 30, 2016 - December 02, 2016
Because of the limited payload and cost-performance, GPS/INS hybrid navigation system is general on small unmanned helicopter. However when GPS wave is blocked, the precision of the measured position is not guaranteed and GPS navigation-based flight control fails. One of the solution for this problem is to use Air-data Sensor (ADS), which measures airspeed. In addition, using airspeed for automatic control improves robustness for wind disturbance. This paper describes the development and the verification of the airspeed sensing and navigation system to cope with these problems by using ADS. An ADS, which has lightweight Pitot tube made from 50mm length acrylic resin on the head of the helicopter, is produced. And GPS/INS/ADS hybrid navigation system based on Extended Kalman-filter is designed by the sensor model built from the measured data on flight experiment of the ADS. By verifying GPS/INS/ADS hybrid navigation system for estimating airspeed and redundancy for invisibility of GPS, the improvement of the precision is restrictively confirmed when GPS wave is blocked. However, some problems are found; the estimating is possible only when the helicopter goes forward, and deteriorated by down wash. To solve these problems, new ADS, which has honeycomb structure for straightening flow and orifices for measuring wind angle, is produced. From the experimental result of new ADS, some points to notice are examined for the future design; inflow to Pitot tube should be kept fully, it should be designed under streamline shape, and prevention of turbulence is required.
