Sensor Network Support for Real-time Indoor Localization of Four-rotor Flying Robots

We present a sensor network based indoor localization system that uses ultrasonic distance measurements for realtime localization of flying four-rotor robots. Such quadrocopters are on-board sensor controlled systems. They are very sensitive to lateral drifts, which cannot be compensated by mounted sensors. In our work, we provide a framework for time-of-flight based localization systems relying on ultrasonic sensors. It is optimized for use in sensor nodes with low computational power and limited memory. Nevertheless, it offers scalability and high accuracy even with erroneous measurements. We implemented the system in our lab using ultrasound sensor that are light enough to be carried around by the flying object. Using this real-time localization system, a position controller can be implemented to maintain a given position or course.