Propeller-Type Wall-Climbing Robot for Visual and Hammering Inspection of Concrete Surfaces

Periodic inspections are necessary in maintaining concrete infrastructures. As efficient and low-cost inspection methods, visual inspection robots and hammering inspection robots to detect cracks and internal defects have been developed, respectively. However, these robots can perform only a single task. To realize multiple tasks by a robot, multiple measurement sensors must be installed considering the stability of the robot on the wall and measurement performance. Parameters, such as weight and size, must be considered to ensure the stability of the robot on the wall. We proposed a propeller-type wall-climbing robot that can capture images and perform hammering simultaneously while moving on the wall. The static model of robot was established by considering various parameters, such as the direction of the propeller's thrust force, weight, and placement of the measurement sensors. This model increases the payload for sensor installation and enables movement on dusty concrete walls with a low friction coefficient. The image captured by the inspection robot was employed for crack detection and width estimation. We confirmed that the hammering sounds generated by the robot showed different frequency characteristics on clear and defective areas. The developed inspection robot can collect adequate data for concrete health monitoring.