Design and Analysis of Truss Aerial Transportation System (TATS): The Lightweight Bar Spherical Joint Mechanism

In aerial cooperative transportation missions, it has been recognized that for small-sized but heavy payloads, the cable-suspended framework is a preferred manner. However, to maintain proper safe flight distances, cables always stay inclined, which implies that horizontal force components have to be generated by UAVs, and only partial thrust forces are used for gravity compensation. To overcome this drawback, in this paper, a new cooperative transportation system named Truss Aerial Transportation System (TATS) is proposed, where those horizontal forces can be internally compensated by the bar spherical joint structure. In the TATS, rigid bars can powerfully sustain the desired distances among UAVs for safe flight, resulting in a more compact and effective transportation system. Thanks to the structural advantage of the truss, the rigid bars can be made lightweight so as to minimize their induced gravity burden. The construction method of the proposed TATS is presented. The improvement in energy efficiency is analyzed and compared with the cable-suspended framework. Furthermore, the robustness property of a TATS configuration is evaluated by computing the margin capacity. Finally, a load test experiment is conducted on our made prototype, the results of which show the effectiveness and feasibility of the proposed TATS.