Simplified approach for modelling pilot pursuit control behaviour in multi-loop flight control tasks

A control-theoretic procedure for modelling human pilot pursuit control behaviour is presented. The procedure allows for the development of human pilot behavioural. models in multi-loop flight control tasks in a simplified framework emphasizing frequency-domain techniques. Beginning with the primary control loops, each control loop is closed using a combination of output-rate feedback and output-error feedback. It is demonstrated that this approach can accommodate any vehicle dynamics that can be stabilized by a human pilot. In addition, the modelling approach identifies vehicle dynamics that approach the limits of human pilot controllability. The well-documented increase in pilot effective time delays that have been shown to accompany vehicle dynamics requiring lead compensation is also replicated by this modelling approach. A method for predicting handling-quality levels that would be assigned to a particular vehicle and task is presented. A visual cue model is included, which can approximate the effects of degraded visual cues. It is shown that this model can be used to reproduce the three most important measurable effects of visual cue quality upon human operator dynamics, namely, an increase in 'effective' pilot time delay, a decrease in crossover frequency, and an increase in error-injected remnant. The ability of the modelling procedure to accommodate different levels of pilot aggressiveness in completing manoeuvres is demonstrated. Finally, an application to a multi-axis rotorcraft flight control problem is presented.