Disturbance observer-based formation tracking control of multiple quadrotors in the presence of disturbances

The presence of disturbances may bring adverse effects to the formation flight of multiple quadrotors. This paper proposes a robust disturbance observer-based feedback linearization that enhances the formation tracking control of quadrotors to achieve the desired formation shapes under the effect of disturbances. The method not only retains the simplicity of the control scheme using feedback linearized quadrotor model, but also has the capability to reject the disturbances. This is achieved by introducing a disturbance observer to estimate and attenuate the lumped disturbance that causes inexact inversion in the feedback linearization of the quadrotor. Then, a distributed formation tracking algorithm is adopted to ensure the quadrotors are able to form up and maintain the desired formation shape and heading via local communication between neighbours with respect to a leader that has nonzero control input. To evaluate the effectiveness of the proposed method, simulation experiments of multiple quadrotor formations using the proposed approach are conducted under several test cases. Results obtained demonstrate the superiority of the proposed control scheme for a more robust formation tracking as compared with the formation without the disturbance observer.