Control method to damp quadrotor slung payload mode

A quadrotor or other vertical lift aerial vehicle measures an angle of a payload slung from the quadrotor relative to a body of the quadrotor. Using this measurement a signal may be generated that adjusts a flight characteristic of the quadrotor to counteract swing in the payload. A feedback function for generating the feedback signal may include proportional and derivative gain functions as well as non-linear signal processing functions. The feedback signal may be added to normal input control signals to cause acceleration in the direction of the payload angle that damp oscillation of the slung payload caused by wind or movements of the quadrotor.