Dual-controller approach to three-dimensional autonomous formation control

The formation-keeping control problem is addressed for the three-dimensional autonomous formation flight of multiple aircraft. The full nonlinear kinematics model describing the relative position and orientation of the formation flight system is used to develop the nonlinear formation-keeping controllers. To deal with the input-output invertibility problem of the formation control system under consideration, a dual-controller approach is presented in this study. First, the original nonlinear formation system is decomposed into two subsystems. Next, the corresponding controller for each subsystem is developed. By invoking the nonlinear dynamic inversion-based control scheme and the well-known structure algorithm, an output-tracking controller with asymptotic stability is achieved for the first subsystem. The second subsystem is simple, and a relative roll angle-hold controller is designed to achieve an exponential convergence rate. Simulation results are provided to demonstrate the effectiveness of the proposed approach.