Noise mapping system with acoustical measurement blimp robot.

To measure environmental noise in our living space, a lot of noise measurement and mapping systems have been studied. However, it is costly because many measurement points are needed to make a noise map. There are problems such as a measurement area reachable by human hands is limited. In recent years, with advances in Unmanned Aerial Vehicle (UAV) technology, various types of UAV have been developed. When UAV is applied to acoustical measurement, it can automatically acquire information such as the environmental noise not only on the ground but also in the air. Multirotor aircraft is frequently used in UAV, however, it causes loud noise as it must always rotate propellers during flying. In this paper, a noise mapping system with acoustical measurement blimp robot is proposed. The developed prototype system is a silent type of multirotor for the purpose of acquisition of environmental noise. The total length of the system is 1.4m, and its weight is about 1.4kg. The system has six propellers to move omnidirectionally, and a system control board with a FPGA SoC which integrates CPU for controlling propeller rotations, sound recording, communicating with host PC, and obtaining the information of the system motion. We evaluated the system in a large room where there are few disturbances such as wind. The result shows that the propeller rotation noise level was reduced 32dB as compared with a general multirotor, and it can make three-dimensional indoor noise map. Moreover, because the various types of sensors are mounted on the prototype system, it can be used for an environmental monitoring.