Stability analysis of digital linear flight controllers subject to electromagnetic disturbances

High intensity electromagnetic radiation has been demonstrated to be a sour ce of computer upsets in commercially available digital night control syste ms. Such upsets can degrade the quality of the control signal ranging from a perturbation error over a few sample periods to a permanent error mode or computer failure. Under these conditions, the primary concern of the contr ol engineer is to insure that the closed-loop system remains stable. A stoc hastic disturbance model and a set of associated stability assessment tools are introduced for determining stability robustness of a nominal closed-lo op system subject to electromagnetic disturbances. The focus is primarily o n night control applications, but the methodology is suitable for any appli cation where highly reliable digital control is needed. The technique is de monstrated on a simple test example and on a stabilizing controller for the Longitudinal dynamics of the AFTI/F-16 aircraft.