A bio-inspired UAV leg-foot mechanism for landing, grasping and perching tasks

Landing and perching on as well as taking off from a variety of different objects reliably like birds are still very difficult tasks for currently available unmanned aerial vehicles (UAVs) including micro air vehicles (MAVs). Research efforts are still needed in order to advance the technology for practical applications. This paper presents a novel bio-inspired design of a UAV leg-foot mechanism, which allows the host vehicle to perform tasks including landing on, perching on, and taking off from either a flat surface or a non-flat object like a tree branch. It also allows the vehicle to do a pick-and-place task for payload transportation. Such combined capabilities can significantly improve the agility and applicability of UAVs for many useful applications. The presented device includes a cable-driven leg mechanism and a cabledriven gripper (called foot for birds) mechanism with three fingers. The mechanical design is based on an analysis of the anatomy of bird legs and feet. The device is intended to have both active and passive grasping capabilities just like how a bird does the similar tasks. Kinematics and dynamics of the mechanical system are modelled and analyzed. An early prototype of the device and a few manually operated grasping examples are also presented.