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Figure 20 depicts, for the four motion conditions, the means and standard deviations of the number of times pilots overshot the ±3° heading criterion about the runway centerline during the 180° turns. When translational motion was added, the decrease in the number of over-shoots was marginally significant statistically (F(1,4) = 5.40, p = 0.081). Interestingly, in this case, the addition of rotational motion made the performance worse, and this result was statistically significant (F(1,4) = 13.26, p = 0.022). Rotational and translational motion did not interact in this measure. These results are not easily explained; however, it must be remembered that in this task the motion platform never presented the pilots with full math-model motion. It is therefore possible that some false cueing in rotation, owing to the motion filter and its selected parameters, had a negative effect on performance in this case. A rough approximation confirms this possibility. For instance, if one modeled the yaw rotation between 0° and 180° by π ψ= sin ωt (10) 2 then the peak yaw rate would be (π/2)ω . Since the peak yaw rates were 50°/sec, this gives a natural frequency of approximately 0.6 rad/sec. This frequency is a reasonable approximation of the heading time-histories, if one discounts the holding times at both 0° and 180°. That is, the periods would be about 10 sec. Since the yaw rota-tional motion filter for this configuration had a break frequency of 0.55 rad/sec, the motion cue’s phase distor-tion at the task frequency was 90°. It is possible that this distortion was adversely affecting performance. Figure 21 illustrates the rms pedal rate for this task. The analysis of variance indicated that the decrease in pedal rate was statistically significant when translational motion was added (F(1,4) = 11.69, p = 0.027). No significant differences were noted when rotational motion was added, and translational and rotational motion effects did not interact. Subjective Performance Data. The average pilot-rated compensation required for this task is shown in figure 22. Large variations in pilot opinion occurred, but no statistically significant differences were noted. Based on the variation in the data, one cannot say that the motion configurations affected the amount of subjective compen-sation required. However, the trends shown in figure 22 follow those in Task 1 (fig. 15). Figure 23 shows the mean motion-fidelity ratings for Task 2. Here motion fidelity was significantly higher when translational motion was present (F(1,4) = 47.9, p = 0.002), whereas the presence of rotational motion did not affect rated fidelity. Rotational and translational effects did not interact. So, pilots believed that the lack of trans-lational motion was objectionable as compared to flight. However, the lack of rotational motion, as long as there was translational motion, was not perceived as a fidelity degradation. Pedal, in Yaw rot. accel., deg/sec2 Ayp, ft/sec2 Yaw rotation, deg 直升机网 www.helicopter.cn 直升机翻译 www.aviation.cn 本文链接地址：Helicopter Flight Simulation Motion Platform Requirements(26) |
