*Article* **Towards Precise Positioning and Movement of UAVs for Near-Wall Tasks in GNSS-Denied Environments**

**Félix Orjales 1,\*, Javier Losada-Pita <sup>2</sup> , Alejandro Paz-Lopez <sup>2</sup> and Álvaro Deibe <sup>1</sup>**


**Abstract:** UAVs often perform tasks that require flying close to walls or structures and in environments where a satellite-based location is not possible. Flying close to solid bodies implies a higher risk of collisions, thus requiring an increase in the precision of the measurement and control of the UAV's position. The aerodynamic distortions generated by nearby walls or other objects are also relevant, making the control more complex and further placing demands on the positioning system. Performing wall-related tasks implies flying very close to the wall and, in some cases, even touching it. This work presents a Near-Wall Positioning System (NWPS) based on the combination of an Ultra-wideband (UWB) solution and LIDAR-based range finders. This NWPS has been developed and tested to allow precise positioning and orientation of a multirotor UAV relative to a wall when performing tasks near it. Specific position and orientation control hardware based on horizontal thrusters has also been designed, allowing the UAV to move smoothly and safely near walls.

**Keywords:** UAV; unmanned aerial vehicles; NWPS; indoor positioning systems; GPS denied; GNSS denied; autonomous vehicles
