Development of a Wall-Climbing Drone Capable of Vertical Soft Landing Using a Tilt-Rotor Mechanism

Wall-climbing drones have many applications, including structural health monitoring of civil structures, such as bridges and high-rise buildings, cleaning of solar panels to improve power generation efficiency, and airplane visual inspections. For these applications, the drone requires a high-payload capacity, and consequently the size and weight of the drone increase. The drone also should not damage the target structures considering the purpose of its mission. Our previous versions of a wall-climbing drone could have high-impact force on the surface where the drone perches and on the platform itself because of the impact caused by a fast pose change and landing speed. In order to overcome this potential risk, a mechanism and a control algorithm for perching on a vertical surface through low-speed pose change are proposed in this paper. The drone platform is based on an X-configuration quadcopter, and a tilt-rotor mechanism is incorporated into the two axes, such that the front thrusters and the rear thrusters are paired. The vertical soft landing mechanism using the tilt-rotors is validated by the experimental tests of the prototype.