3D environment mapping and self-position estimation by a small flying robot mounted with a movable ultrasonic range sensor

The light weight of ultrasonic sensors makes them useful for collecting environment information from mobile robots. Ultrasonic sensors are generally used in a circular formation in surface-moving robots, but this is not suitable for small flying robots, which require small size and light weight. Here we created a movable ultrasonic range sensor by combining a small, lightweight servomotor and a single ultrasonic range sensor. This sensor could perform 360° measurements of the distance between objects and the robot. We furthermore constructed a measurement system to perform 3D environment mapping and self-localization by equipping a small flying robot with this movable ultrasonic range sensor and a ground-facing ultrasonic range sensor for altitude measurements. We verified the system by means of a flight test and found that 3D environment mapping and self-localization were realized in real time.