As infrastructure built during Japan’s post-war economic growth period continues to age rapidly, there is an urgent need for safer and more efficient inspection technologies to replace traditional manual methods such as visual and hammering inspections. In this study, we developed a wall-climbing robot designed to perform non-contact surface inspections using an infrared camera. The robot is equipped with four independently controlled propellers that generate thrust to press the body against the wall, allowing it to maintain adhesion and move across vertical surfaces using passive wheels without drive motors. The design process involved 3D CAD modeling and performance evaluations through thrust measurements under various voltage inputs. Wall-climbing experiments were conducted to verify the robot's ability to move vertically and horizontally on a concrete wall. Results showed that stable horizontal movement was achieved with smooth thrust control and passive wheel support. However, during vertical ascent, it was observed that improper propeller tilt angles reduced the effective vertical thrust, leading to instability and slippage. These findings confirm that precise thrust vector control is essential for maintaining reliable wall adhesion. The developed robot demonstrated sufficient potential for stable locomotion and defect detection using infrared imaging. Future work will focus on implementing real-time autonomous control of propeller speed and tilt angle, as well as integrating the infrared inspection system for practical application in infrastructure maintenance.
ASANO et al. (Wed,) studied this question.