Free-Flow Tunnel Inspection Support Devices Aiming at Labor Saving of Visual Checking

Abstract

Small and medium-sized hydroelectric power plants are scattered in mountainous areas of Japan. Many tunnels that have been constructed for the purpose of introducing water have been in operation for decades, and inspections to aging deterioration are indispensable, however checks and maintenance work within the tunnels where the ceiling is low and water is flowing is very burdensome. This research aims at labor saving of visual check work of an inspector who moves through a narrow tunnel and searches for a deformed portion, and a simple imaging support device with a camera on a walking aid and autonomous operation at a constant speed in the tunnel. In this article, a prototype of a walking assist type inspection device and a self-propelled monitoring robot that creates a developed image of the wall surface are described. The prototype device is tested in a free-flow tunnel at the Tsukuyone Hydroelectric Power Station in Tottori Prefecture where water intake into the tunnel is stopped due to renewal work from 2018 to 2019, and its practicality is evaluated.