IMPROVED TUNNEL DISPLAY FOR CURVED TRAJECTORY FOLLOWING - CONTROL CONSIDERATIONS

Improvements of a previously developed tunnel display for curved traje ctory following are presented and theoretically analyzed. The success of earlier versions of this display can be attributed to the combinati on of the perspective tunnel image with a superimposed predictor symbo l. The tunnel image provides the spatial awareness and preview of the trajectory forcing function, and the predictor provides vital guidance and control information. Two main shortcomings of these earlier versi ons, occurring for large and sluggish aircraft requiring longer predic tion times, are addressed: 1) poor performance in transitions between straight and curved trajectory sections and 2) poor positional accurac y in the presence of biases or low-frequency disturbances. The two bas ic improvements addressing these shortcomings, and incorporated into a n improved display layout, are 1) an algorithm for generating trajecto ry shapes that are well matched with the average vehicle response and 2) an actively driven predictor reference window, yielding improved pr edictor guidance information. The improvements combine the advantage o f a vehicle path predictor that performs as a well-designed natural fl ight director, with improved curve transition behavior and improved po sitional accuracy in the presence of slowly varying cross winds.