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Helicopter Flight Simulation Motion Platform Requirements(8)

时间:2011-11-12 12:15来源:蓝天飞行翻译 作者:admin
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Young showed that platform motion reduced the pilot’s response time to a failure or disturbance while on a glide path compared to the no-motion case (ref. 18). In the same paper, results were presented showing that when helicopter pilots and highly trained non-pilots hovered an unaugmented helicopter model, their performance signifi-cantly improved with the addition of motion. Performance did not improve for the moderately trained non-pilots.
Hosman and van der Vaart (ref. 19) found that performance improved with motion in roll for both disturbance rejection and tracking over that of the no-motion case. However, the roll motion in this case included the spurious lateral specific force cues owing to the lack of simulator translational motion available to account for coordination.
One of the few studies that has examined the performance effects of full motion versus no motion was performed for the roll axis by McMillan et al. (ref. 20). That study also showed significant improvement in tracking, but little improvement in a transfer-of-training metric when full motion was present over the no-motion case. Similar results were present by Levison et al. (ref. 21).
Boldovici (ref. 8), in his balanced presentation on both sides of the motion argument, gives a set of reasons for employing motion platforms: (1) to reduce the incidence of simulator sickness (note that this argument is used both for and against motion), (2) users’ and buyers’ acceptance of improved validity, (3) trainees’ motivation,
(4) to learn how to perform time-constrained dangerous tasks, and (5) to overcome the inability to perform some tasks without motion.
For difficult control tasks, early studies showed that motion allows a pilot to form the necessary lead compen-sation more readily with acceleration cues than with the visual displays alone (refs. 18, 22). For stabilization tasks a pilot will often use this lead compensation to reduce the open-loop system phase loss and thus allow an increase in the pilot-vehicle open-loop crossover frequency to a point higher than that achieved without motion (ref. 23). This increased crossover frequency, with the same or better phase margin, yields tracking performance more akin to that of flight.
Interestingly, the FAA has been a strong supporter of platform motion. Indeed, if a device is to be called a simulator by the FAA, it must have motion. If a device does not have motion, then the FAA terms it “a flight training device” (refs. 3, 5).


Developing Requirements for Motion
Since instances have clearly arisen in which the addition of platform motion shows significant benefits, the question remains “For those instances, what are the motion requirements?” Defining the necessary require-ments for the quality, or fidelity, of that motion has been difficult. The fact that requirements are not known is evident from the following quotes from the literature. “Unfortunately, explicit definitions of ‘valuable’ motion fidelity, for specific research or training objectives, remain for the most part undetermined” (ref. 24). “Formal experiments to determine acceptable attenuation and phase lag of the force vector are limited in scope . . .” (ref. 25). “Future research topics in the area of flight simulation techniques should encompass minimum essential visual and motion cueing requirements for a particular flying mission” (ref. 2).
 
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