Predictor-tunnel display and direct force control for improving flight path control

The improvement which predictor-tunnel displays provide for trajectory control can be enhanced with the application of direct force control. The guidance information presented in a 3-dimensional format on the display consists of the command trajectory in the form of a tunnel and the aircraft position indicated by a predictor at an appropriately selected time ahead. Direct force control is a concept which enables a direct generation of forces acting at the aircraft. Thus, the commanded force is immediately effective, without a time lag. Pilot-centered requirements are considered for achieving best performance for compensatory control of the predictor-aircraft system as the controlled element. With reference to these requirements, a predictor control law is developed for achieving a controlled element which requires minimum pilot compensation. This goal is supported by the dynamic characteristics of the aircraft which are due to the direct force control. Comparison with a predictor-aircraft system employing conventional pitch control shows that direct force control yields improvements in the dynamics characteristics of the closed-loop pilot-predictor-aircraft system. Results from an evaluation based on simulation tests are presented for experimental validation.