Comparison of Simulator Platform and Flight Tasks on Adverse Rotorcraft Pilot Coupling Prediction

Previous investigators have found that obtaining the same results using different simulation facilities for notionally identical test can be difficult to achieve. This was also found to be true in the EC-Framework 7-funded ARISTOTEL project. This project used two simulators in parallel - the HELIFLIGHT-R Simulator (HFR) at the University of Liverpool and SIMONA Research Simulator (SRS) at TU Delft in a study aimed at creating tools and techniques to predict, detect and eliminate rotorcraft pilot couplings (RPCs). Therefore, an essential part of the investigation was to understand the effect of using these two simulator platforms on the ability of pilots to detect rotorcraft pilot couplings (RPC). Similarity between the two facilities was verified both objectively and subjectively for three key simulation components: the open-loop aircraft flight dynamics model, the visual display system and the motion drive system. The closed-loop pilot-awarded subjective visual and motion cueing ratings indicated that the two simulators had reached a good level of similarity for the latter two of these items. Inspection of non-linear responses to pre-defined control inputs showed the same for the aircraft model. Pilot-in-the-loop flight simulation test campaigns were conducted on four ADS-33E-PRF maneuvers: Acceleration-Deceleration, Vertical Maneuver, Hover Maneuver, and Roll Step. The data obtained was analyzed in terms of subjective Handling Qualities Ratings and Pilot-Induced-Oscillation Susceptibility Ratings and objectively using the pilot cutoff frequency. It was found that the ratings obtained using SRS were generally higher than the corresponding data from HFR. An explanation for this finding was provided by using a modified time-varying power frequency metric to distinguish pilot control activities in the frequency domain between the two simulators. Pilots in SRS generally have higher stick activity intensity than when flying in HFR. The subjective and quantitative results show that SRS appears to provide a more RPC-susceptible environment than HFR and this appears to be due to its slightly lower resolution visual environment when compared to HFR.