UAV with two passive rotating hemispherical shells and horizontal rotor for hammering inspection of infrastructure

Infrastructure is vital for economic development and growth and the destruction of infrastructure could lead to economical losses and fatalities. Periodic inspection and maintenance must be performed to avoid such incidents. However, inspection, which was traditionally performed manually, is laborious, expensive, time-consuming, and unsafe for the human inspector. UAVs have been proposed in recent studies as an alternative for conducting infrastructure inspection. In this paper, a system comprising a quadrotor UAV, passive rotating shell mechanism, horizontal rotor, and hammering device is proposed to provide a robust solution for performing hammer test in an infrastructure - a complex-structured site. Each subsystem is responsible for a vital function. The UAV acts as the main platform for efficient and safe inspection, the passive rotating hemispherical shell mechanism ensures protection and better stability during a collision with the obstacle, the horizontal rotor helps with the hammering action, and the hammering device performs the task. The paper describes the general idea, design and analysis of main subsystems, fabricated prototype, and conducted flight experiments. The capabilities of the proposed system were verified by conducting flight experiments. The passive rotating shell mechanism is shown to be effective against obstacles while the horizontal rotor is helpful in hammering action.