Application of Two Time-Scale Separation NDI Controller to a Dual Aerodynamically-Controlled Missile.

Agile dual aerodynamically-controlled (DAC) missile presents a sophisticated flight control problem given the inherent missile-nonlinear and tail-fin-canard coupling dynamics that render the system non-affine in control. Given the complexity of the plant, application of most advanced controller present a complex modelling challenge. This paper investigates application of two time-scale separation nonlinear dynamic inversion to the longitudinal dynamics of a dual-controlled missile. NDI was selected because of its simple but sufficient nature for agile missile with nonlinear dynamics. The proposed NDI topology inverts the tail-fin and canard dynamics separately to obtain the canard and tail-fin commands. The NDI controlled response of the dual controlled missile are compared with a baseline three-loop-autopilot. Key observation was that the NDI controller combines the diverted and dual mode thus reducing control surface deflections suggesting better control authority over gain scheduled controller.