Physical Contact with Wall using a Multirotor UAV Equipped with Add-On Thruster for Inspection Work

Inspection and maintenance work at heights car-ries significant risks and is time consuming for human workers. Therefore, aerial manipulators are expected to replace these tasks. This paper presents a multirotor UAV equipped with a single horizontal thruster. This minimal configuration en-ables physical contact while keeping the airframe's attitude horizontal for non-destructive inspection work on vertical wall surfaces. The thrust required to move forward and backward during a physical contact task is independent of the thrust required for hovering, simplifying control of the UAV. Utilizing onboard sensors, the UAV automatically maintains a forward-facing posture against the wall, initiates and sustains contact, and disengages when necessary. Additionally, the UAV in this study incorporates an ultrasonic thickness measurement device, allowing for the verification of automated measurements while in flight.