Coordinated transportation of a group of unmanned ground vehicles

This paper studies a coordinated transportation problem of a group of unmanned ground vehicles (UGVs). These ground vehicles belong to two categories: master vehicles and slave vehicles. A two-step strategy is proposed to solve this problem. First, let the master vehicles move along ideal trajectories. Then, let the slave vehicles move into the area surrounded by master vehicles and move together with them. By the two-step strategy, the coordinated transportation problem is divided into a tracking problem and a containment problem. A PIⁿ-type tracking protocol and a PIⁿ-type containment protocol (P and I stand for Proportion and Integration, respectively; Iⁿ implies that the protocol includes high-order integral terms) are proposed to solve these two problems. It is proved that the coordinated transportation problem can be solved by two proposed protocols with proper parameters if for each follower there exists at least one leader which has a directed path to this follower. Finally, a simulation example is presented to demonstrate the effectiveness of the proposed algorithms.