Leader-Follower Formation Suboptimal Control for Quadrotors

In this work, a leader-follower formation control problem of quadrotors is investigated. The quadrotor dynamic model is represented by unit quaternion with the consideration of external disturbance. Nonlinear H∞ design approach is introduced and robust controllers for both leader and follower robots are derived by solving a Hamilton-Jacobi inequality following from a result for general nonlinear affine systems. Then some robustness conditions of the proposed controllers are obtained by selecting appropriate parametrised Lyapunov functions. The resultant state feedback controllers establish the asymptotically stability of the closed-loop nonlinear system. In addition, integral backstepping (IB) controllers are also derived for the leader-follower formation control problem. The purpose of designing IB controllers is to evaluate the robustness of H∞ controllers by comparison. The simulation results from both types of controllers are compared and robustness performance of the H∞ controllers over the IB controllers are demonstrated.