Independent velocity control of the longitudinal motion of quadrotors*

The problem of independent control of the horizontal and the vertical velocity in the longitudinal motion of a quadrotor in cruising mode is studied. A two-layer controller design scheme is proposed. Using the inner controller, the design requirement of triangular decoupling is satisfied and the general expressions of the controller matrices and the triangular closed loop transfer matrix are analytically determined. For the external loop, a MIMO PID controller is designed to achieve diagonal decoupling with simultaneous stability. The results are successfully applied and tested through a nonlinear computational experiment for a climbing maneuver.