[abstFig src='/00280003/07.jpg' width=""300"" text='Photograph of HORNET catching onto a wall' ] During the high economic growth period in Japan, the development of new infrastructures was promoted and numerous bridges and buildings were constructed. Currently, the walls of bridges and buildings are inspected manually. This manual inspection process is expensive and time-consuming, and inspectors may be placed in dangerous situation. In this study, a robot that moves stably on a wall while maintaining a distance from the wall was developed to enable low-cost, safe inspection. Several characteristics of the robot were measured, and the possibility of using the robot in practical applications was assessed based on the measurement results.

Many social infrastructures and buildings are aging. Therefore, inspections to find deteriorated parts to prevent accidents are important. However, significant costs and inspection time are required for the current technologies. Therefore, inspection methods using robots are attracting attention. As the most appropriate option to traverse freely on concrete bridges and building walls is by traversing with lift force from propellers, a robot called HORNET has been developed that can run along a wall with two rotors. However, the floating-type robot with propellers could drop from a wall if hit by strong wind. Therefore, a gyro sensor was installed in the robot to detect its posture and adopted a simple maneuvering assist control to reduce the above-mentioned issue. In this study, the motion of HORNET was analyzed and a simple control system was designed to realize the maneuvering assist control. It was confirmed that the resistance of HORNET to the crosswind was improved by adding the control system.

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Many structures such as bridges, buildings, tunnels and dams had been constructed during the high economic growth period in Japan. The deterioration of these structures has become a big social problem. The maintenance method which finds the minor damages on the structures is important for the life extension of many structures before the progress of deterioration advances. When the inspections become frequent, the huge cost is needed. Robots are said to be useful for the management and maintenance of many old structures because the conventional method will intensify the strains on economy. In this study, we have created a flying robot HORNET with tilt-rotors and two wheels. HORNET can move on a vertical wall keeping a constant distance between the robot and a wall. Then, it is very easy and safe to control the robot manually. In addition, the electric power consumption of HORNET can be smaller than hovering robot like drones because HORNET can hang on wall with claws of the wheels. We have examined the effects of the state of wall surface and the tilt angle of rotor surface on the electric power consumption of HORNET. According to the experimental results, it has been confirmed that the electric power consumption is reduced when the state of wall surface is rougher and the tilt angle of rotors is more parallel to the ground. It is possible to become a practicable wall inspection robot by adding the improvement to HORNET.