Formation control for autonomous fixed-wing air vehicles with strict speed constraints

We present a formation-control algorithm for autonomous fixed-wing air vehicles. The desired inter-vehicle positions are time-varying, and we assume that at least one vehicle has access to a measurement its position relative to the leader, which can be a physical or virtual member of the formation. Each vehicle is modeled with extended unicycle dynamics that include orientation kinematics on SO(3), speed dynamics, and strict constraints on speed (i.e., ground speed). The analytic result shows that the vehicles converge exponentially to the desired relative positions with each other and the leader. We also show that each vehicle’s speed satisfies the speed constraints. The formation algorithm is demonstrated in software-in-the-loop (SITL) simulations and experiments with fixed-wing air vehicles. To implement the formation-control algorithm, each vehicle has middle-loop controllers to determine roll, pitch, and throttle commands from the outer-loop formation control. We present SITL simulations with 4 fixed-wing air vehicles that demonstrate formation control with different communication structures. Finally, we present formation-control experiments with up to 3 fixed-wing air vehicles.