Guidance and control of a scaled-down quad tilt prop PAV

In this paper, a flight control and guidance method for a scaled-down quad tilt prop personal air vehicle (PAV) is presented through simulations and flight tests. The developed scaled-down PAV does not fully transit into a fixed-wing flight mode, but longitudinally tiltable nacelles are used to control the longitudinal translation speed. This design concept can realize a flight maneuver with minimized attitude change because it is only necessary to tilt the nacelles of the propellers and not the attitude angle of the whole body. Although controls of a similar tilt-rotor and quad-tilt vehicles have been reported, a research on a guidance algorithm of a vertical take-off and landing (VTOL) PAV is deficient. Therefore, this paper focuses on the guidance algorithm for the quad tilt prop PAV that requires minimized fluctuation for a passenger. The dynamic behavior and responses of attitude and velocity controllers are identified with reasonable accuracy for a simulated test. Using this model, a guidance algorithm is developed for a circular path to minimize variation of a control input and system states. Through the simulated evaluation against the widely-used proportional navigation guidance algorithm, it was found that the proposed circular path guidance method has better performance in terms of total variation. In addition, through the flight test, the feasibility of the current concept for using the propeller nacelle tilt angle as a control input in forward speed control of a quad tilt prop PAV is proved.