Piecewise identification of manual control dynamics during control law changes

In-flight failure scenarios often involve flight control law switching that can potentially result in adverse aircraft-pilot-coupling or unwanted airframe loads. The experimental setup and results from an investigation focusing on the effects of control law switching on pilot manual control dynamics using desktop based pilot-in-the-loop simulation are presented in this paper. Pilots were presented with tasks requiring them to compensate for disturbances in aircraft longitudinal dynamics due to medium and severe turbulence. Off-line parameter identification was then used to derive pilot model parameters from simulation data and thus, infer changes in manual control characteristics due to switching between three control laws. This resulted in piecewise linear pilot models and quantified the inter-subject differences suitable for inclusion in the future design of robust flight control systems. Increased turbulence intensity was found to reduce inter-subject differences both in terms of pilot model parameters and the open-loop pilot-vehicle system crossover frequency.