Self-Spin Enabled Docking and Detaching of a UAV-UGV System for Aerial-Terrestrial Amphibious and Independent Locomotion

As an amphibious system, aerial-terrestrial vehicles have demonstrated remarkable environmental adaptability. In order to expand their synergistic advantages, in this letter, an Aerial-Terrestrial vehicle consisting of a pair of unmanned aerial vehicle (UAV) and unmanned ground vehicle (UGV) is proposed, which is capable of performing UAV-UGV autonomous docking and detaching. Under the docking modality, the proposed vehicle can perform amphibious locomotion to adapt to rugged terrains. Under the detaching mode, the distributed UAV and UGV subsystems gain enhanced accessibility to the confined space and can share both air and land information, which is promising to accomplish collaborative missions. In order to achieve the docking and detaching of the two subsystems, a screw-like binding mechanism is proposed. To implement the binding mechanism, it is separated into two pieces, i.e., 'screw' and 'nut,' which are duel-functioned as the landing gear of the UAV or the UGV roof, respectively. To improve the success rate of docking, a mathematical model of the binding mechanism is established to calculate the ideal curve of the guiding surface, which provides important cues for the mechanism fabrication. With such a binding mechanism, UAV or UGV can execute docking or detachment via screwing-like self-spinning motion. The spinning torque of the UAV and UGV are calibrated by torque measurement tests. As a result, each independent vehicle can generate sufficient power to lock or detach via its original actuators, thus omitting the extra actuators. The full stage control, including air-ground docking-detaching and amphibious locomotion, are validated experimentally.