Unmanned Aerial Vehicles (UAVs), often referred as drones, have been widely implemented for civilian, commercial, search and rescue, and military operations with the advantages of easy deployment, low cost, automation, as well as, most importantly, allowing the execution of dangerous or difficult tasks remotely and safely. The advantages boost a large market request for the development and application of UAVs worldwide. However, current UAVs are equipped commonly equipped with a passive landing gear, such as a skid or wheel landing gear, which limits the application of UAVs to an even and flat ground for safe landing and taking off; this constraint impedes the development of UAVs for application in extreme environments, such as war fields and remote wilderness where proximate level ground is inaccessible. Without an active power, the passive landing system has an essential delay, resulting in a high failure rate, especially in landing on uneven ground. The ability of UAVs to land on un-level ground would help broaden the application of UAVs; in particular, the ability to go beyond thermal imaging to locate a lost hiker with the ability to land and deliver life sustaining resources in a more timely manner offers a benefit to human rescue missions. Current research on active landing gear and alleviate the obstacles to some degree and realized an adaptive landing; however, current active landing gears are built with bulky sizes, heavy weight and numerous electronic sensors, which increases the complexity of the structures and control algorithms, increases flight interference due to the overload in mass and aerodynamics, and raises the cost. This paper presents an innovative robotic landing system consisting of three slanted legs, each individually controlled by a DC motor through a lead screw mechanism. The foot of each leg has an integrated force sensor for detecting ground touch. An inclinometer is installed on the platform of the landing system to sense the UAVs orientation during landing. An innovative landing strategy is proposed to realize automatic landing. The landing system can keep the platform horizontal when it lands on the ground by extending or retracting the legs. Two indoor experiments including slope ground and stepped ground were conducted for preliminary tests. Two outdoor experiments of cement stepped ground and slopped grass ground are tested to verify the practical application of the robotic landing system in various terrains. The feasibility and effectiveness of the robotic method has been demonstrated by the indoor and outdoor experiments.


Development of a Robotic Landing System for UAVs Applied in Various Terrains

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

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