Development of UAV Indoor Flight Technology for Building Equipment Works

In the Japanese construction industry, the number of young workers is decreasing and skilled workers are aging. For that reason, efforts to improve productivity by using information technology (IT) and robot technology are under way. One of them is UAV. In civil engineering work, UAV is utilized in volume management of the foundation ground. In building work, quality is managed by using images taken from the sky. However, there are no cases of using UAV in buildings under construction. Also, there are no examples where UAV are used in installations that need to work in contact with the surrounding environment. Facility construction is mostly work in the building, especially in the vicinity of the ceiling using temporary scaffolding. In order to utilize UAV in facility construction, it is necessary to perform self-positioning without GPS, to recognize the surrounding environment, and to make direct contact with the surrounding environment. One of the tasks near the ceiling in facility construction is air volume measurement. Conventionally, by using a temporary scaffold, wind speed distribution immediately below the diffuser is measured by a handy type anemometer, and air volume is calculated by multiplying the average value by the opening area. In recent years, a device for measuring the air amount passing through by closely attaching a hood for collecting wind to the ceiling surface has been used. However, it is necessary to measure by using a temporary scaffold for the diffuser of a room with a high ceiling like a factory. Also, if production equipment is installed right under the diffuser, even the installation of the scaffold may be difficult. Due to these facts, the use of UAV has merit. In this research, in order to develop a UAV for use in indoor facility construction, we made a prototype of a UAV equipped with an "air volume measurement unit" and evaluated it. In the unit, five wind speed sensors are arranged on the downstream side of the wind collecting hood. The UAV is a multi-copter with 8 propellers, and the frame is a lattice structure in order to mount the airflow measurement unit in the center. The position and attitude of the UAV were obtained by extracting two red circular marks mounted on the UAV from the image acquired by a single lens camera, and recognizing the elliptical shape, size and position of the marks. The experimental field was a temporary ceiling in which a diffuser was arranged. In the flight experiment, the route was designated from the floor surface to the diffuser, and the UAV made to fly this route. The flight path was measured with a motion capture system using an infrared camera, and the approach performance to the diffuser was evaluated. In order to check the contact state with the diffuser, the air volume was measured, and the degree of adhesion of the wind collecting hood was confirmed. This paper discusses the detailed experimental results, and problems involved.