Simulation investigation of a comprehensive collective-axis tactile cueing system

A collective axis cueing system has been developed for helicopters that cue the pilot to a variety of envelope limits associated with the engine and drive systems including transient and continuous transmission torque limits, rotor rpm limits, and the optimal rpm following a one engine inoperative emergency. The cueing system uses neural network and linear model based algorithms to predict approaching limits, and then estimates the constraints on the collective control position to ensure that the limits are not exceeded. The constraints are relayed to the pilot through a combination of soft stop and stick shaker cues. This collective cueing system has been tested using a real-time piloted simulation of a UH-60 Black Hawk. The results of the simulation show that collective cueing leads to a significant reduction in pilot workload, decreases time required to conduct a specific task, and improves task accuracy for aggressive maneuvers. In addition, it allows the pilot to fly in true "heads up, out-the-window" fashion following a single engine failure. Finally, the study shows that with the judicious use of different types of cues (soft stops and stick shakers) and intuitively chosen stick shaker frequencies, multiple limits can be cued through the collective without confusion.