IJCAS

This paper proposes a new approach to the carrot-chasing guidance law to provide an accurate trajectory tracking function. The ahead-distance approach used in the conventional method highly depends on trajectory shapes and the complex geometric manipulation causes degraded performance. To overcome this disadvantage, the ahead-distance is replaced with the ahead time and the desired trajectory to the target point on the reference trajectory is generated using the Hermite spline interpolation. The desired aircraft’s states at the current time are estimated from the generated trajectory function and used to develop three kinds of the trajectory-tracking controllers. The effect of the ahead-time on achievable trajectory-tracking accuracy are thoroughly investigated through their applications to the rotorcraft guidance problems, which are defined by the prescribed trajectories for the transient turn and pirouette maneuvers. Finally, the guidance laws are applied to the complex mission profile consisting of the hover, acceleration, pop-up, helical turn, pop-down, and deceleration maneuvers to validate their usefulness. The best performance of guidance laws is investigated by the simulation around 5 second-ahead-time value. Hence, the proposed guidance laws provide accurate trajectory-tracking performances.

Keywords: Ahead-time, carrot-chasing guidance law, guidance law, rotorcraft, trajectory tracking.