Optimization of the equivalent mechanical characteristics of active side sticks for piloting a controlled helicopter

Abstract

Active side sticks offer the possibility to adjust the force-feel characteristics to account for various piloting tasks and flight conditions. This promises a decrease in pilot workload and an increase in handling qualities. However, the optimum force-feel characteristics are not well understood and modeled; therefore, their tuning still rely on experimental methods. Experimental pilot-in-theloop methods are time-consuming, expensive and have to be repeated with every change in control law dynamics. If a purely mathematical method for force characteristics optimization could be developed based on a better understanding of the principles underlying good force-feel systems, then the optimization could be done more efficiently and offline. This paper presents our current developments and achievements towards this new understanding to assess if and how a purely mathematical method could be derived from selected experiments. Even if this final goal could not be derived yet, the paper presents the selected approach and the lessons learned so far. More precisely, a simulatorbased experiment was developed to provide the data for the later analyses and the identification of mathematical models suitable for that purpose. For this experiment, a roll tracking task is considered whose evaluation is based on both a qualitative (Cooper-Harper rating) and a quantitative criterion. The very encouraging results obtained so far on this scenario are detailed.

Results of the pilot assistance system “Assisted Low-Level Flight and Landing on Unprepared Landing Sites” obtained with the ACT/FHS research rotorcraft

“…To avoid this, the idea was developed to find a purely mathematical way for calculation of the optimal stick dynamics, given only the controlled helicopter dynamics, as described in Ref. [40]. This approach incorporated a pilot model, which was trained with data gathered with a tracking task flown in a piloted simulation.…”