Sensor fusions for constant thrust aircraft navigation in pitch plane

Abstract

Constant thrust aircraft navigation is an altitude hold mode in air transportation systems, air refueling systems, traffic alert and collision avoidance system and automatic dependent surveillance broadcast based collision avoidance, as well as in surveillance operations of unmanned aerial vehicles. In pitch plane, determination of the elevator input options available to maneuver the aircraft from its altitude hold mode using constant thrust is an important problem. Such inputs are useful to avoid time critical obstacles or collisions sensed in the horizontal plane. In this paper, it is shown that sensor fusions in feedback path are particularly attractive to generate such elevator inputs. Given the nonlinear aircraft’s linear time-invariant model based controllers at the inner loop, constant thrust aircraft navigation requires these controllers derived for sensor fusions. That is, in state feedback format, usually an identity matrix is considered for all state variables as measurements whereas in the present paper, particular combinations of the sensors in the feedback path are considered. A procedure to derive the stabilizing controllers that accommodates the sensor fusions is presented in partial pole placement framework. Then the nonlinear aircraft embedded with such controllers is simulated with capabilities to avoid the time critical obstacles. Examples by using a micro air vehicle model are illustrated.