Formation control of VTOL UAVs without linear-velocity measurements

We address the formation control problem without linear-velocity measurements for a group of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAV) with a fixed and undirected communication topology. The vehicles among the team are required to track a desired reference linear-velocity and maintain a desired formation. Our control design is achieved in two main steps. First, an intermediary control input is designed for the translational dynamics, from which we extract the desired system attitude and thrust achieving the formation objective. Then, the torque input for the rotational dynamics of each vehicle is designed to drive the actual attitudes to the desired ones. To obviate the need for linear-velocity, we use instrumental auxiliary variables in each step of the control design. The stability of the overall closed loop system is rigorously established. Simulation results are provided to show the effectiveness of the proposed control scheme.