  This paper presents an optimal guidance approach for a UAV navigation between
two given points in 3D considering the wind influence. The proposed cost
function to be minimized involves the weighting of the travel time and the
control energy. An analytical expression is derived for the optimal cost
yielding a fourth-order polynomial whose positive real roots correspond to the
optimal travel times. The optimization problem is shown to be equivalent to the
Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) optimal guidance approach for
the case of a constant wind acceleration. Case studies for the rendez-vous and
the intercept problems are shown through simulation examples for different wind
conditions.
