Robust homography-based visual servo control for a quadrotor UAV tracking a moving target.

•Compared with the linear HBVS framework and the previous nonlinear HBVS framework, a nonlinear robust hierarchical HBVS framework for the under-actuated UAV is proposed. The system’s stability is enhanced to be asymptotically stable with disturbances rather than locally asymptotically stable or asymptotically stable without disturbances in previous works.•Compared with the authors’ previous HBVS method, a new command attitude extraction method is first proposed to extract the desired attitude from the control input of the outer loop in the UAV’s body frame rather than the inertial frame to avoid the coupling in the controller design.•A robust constrained control algorithm is developed by integrating a cascaded filter-based estimator, the adaptive method and a smooth hyperbolic tangent function in the augmented backstepping control scheme. The constrained translational motion control input can satisfy the extraction condition to guarantee the non-negative total thrust and avoid singularity. The filter-based estimator and the modified adaptive method with an integrated update law can deal with the unknown image depth and the uncertainties concurrently.