Homing on a moving dock for a quadrotor vehicle

A homing control law for a quadrotor is presented to drive the vehicle towards a moving target at constant longitudinal velocity. The vehicle is driven to the homing point through force control with an inner-outer loop control strategy. For the outerloop, the position and velocity features are exploited to derive a control law that directs the vehicle to the homing target while ensuring it never collides with ground. The fast inner-loop sets the appropriate thrust and aligns the vehicle thrust direction with the reference force direction. In order to reject wind disturbances, the homing control law is augmented with an estimator for constant, or slowly time-varing, unknown inertial forces. The control law guarantees the exponential convergence of the distance to zero and that the vertical approach and landing is smooth.