Symposium on the Role of the Vestibular Organs in Space Exploration (1970) / Chapter Skim
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EFFECT OF INSTABILITY DURING ROTATION ON PHYSIOLOGIC AND PERCEPTUAL-MOTOR FUNCTION
EFFECT OF INSTABILITY DURING ROTATION ON PHYSIOLOGIC AND PERCEPTUAL-MOTOR FUNCTION
Pages 307-330
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From page 307... ...
Perceptual-motor performance was not degraded; rapid head turns caused no more decrement in performance during perturbation than in stable rotation; and the rate of OGI extinction was the same, even though the extent was less, in the perturbating environment. The consistency of results supports the hypothesis that perturbation during rotation creates a constant stimulus to the vestibular system and, as such, keeps the receptor in a partial refractor state which, in turn, raises the threshold for sensitivity to cross-coupled acceleration.
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From page 308... ...
As stability of a rotating space vehicle is related directly to its total mass, the relatively light state-of-the-art vehicles would be particularly susceptible to instability from mass disturbances. In a discoid or toroidal vehicle rotating about its principal Z-axis, a crewman alined with one of the transverse Xor K-axes could be subject not only to the disturbing effects resulting from his active head movements relative to the spin plane, but also to a variety of oscillating forces beyond his active control.
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From page 309... ...
An inertial unbalance produced by an uncompensated mass movement along a transverse axis within the plane of spin will couple with the moment of inertia about the spin axis to produce a disturbance about the transverse axis that is directly proportional to the initial vehicle spin rate and the product of the moments of inertia of the transverse and spin axes. This generated spin coupled with the initial vehicle spin will produce varying angular velocity patterns.
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From page 310... ...
It also provides a means to perturb the cabin and to vary the angular velocity so inertial forces within the chamber simulate the vector patterns predicted for various sizes and configurations of spacecraft rotated to produce artificial gravity. No information on how such perturbations affect general performance is available; this study is the preliminary effort to generate such data.
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From page 311... ...
, secondary factors had to load at 0.30 or above. Previous studies indicated that acceleration produced by the product of angular velocities resulting from head turning and vehicle rotation reduced performance in a rotating environment and that this reduction was partly due to visual location of the task display (ref.
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From page 313... ...
Motion out of the spin plane was sinusoidal and, therefore, predictable in time and magnitude. Tasks requiring head turns in different planes impose cross-coupled stimuli on the semicircular canals that vary in magnitude and direction, depending on subject orientation, vehicle rotation rate, and motion due to the perturbation.
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From page 314... ...
orientations of the subject for K-axis head turns at 0°, 45°, and 90° interplanar angles to the centrifuge spin plane by simply rotating the chair (fig.
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From page 315... ...
To provide an integrated display for data records, three readouts (polygraph EOG, oscilloscope VOG, and a digital count of the EMC frame number) were individually photographed by separate television cameras and synchronized into a single picture by a special effects generator for video taping and/or subsequent kinescoping.
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From page 316... ...
Figure 8 shows the mean net RATER score for the full sequence as a function of interplanar orientation for each of the dynamic modes. This figure makes the two observations mentioned above more apparent.
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From page 317... ...
-NUMBERS ARE EMC FRAMES FROM START SIGNAL CAMERA SPEED - 8 FRAMES/SECOND 21 "iio O GAZE POSITION WITH HEAD STABLE (TURN COMPLETED)
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From page 318... ...
A comparison of figures 10 and 11 indicates the major difference between the EMC and VOG data-the EMC fixes gaze position in the field of regard independent of head position, whereas the VOG indicates only gaze position relative to the head. In figure 11, prior to frame 22, when the head becomes stable at the end of head turn, gaze positions 18 to 21 could be repositioned relative to the changing field of regard by correcting relative to a reference mark in that field.
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From page 319... ...
During combined rotation and perturbation exposures of subjects and examiners in the Convair MRSSS, impressions of altered vestibular suppression rates have been consistently reported that indicate the perturbating environment is more easily tolerated. Experiment 3 provides statistical comparison of rate and transference of vestibular suppression of the OGI resulting from crosscoupled angular acceleration as a function of the presence or absence of perturbation.
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From page 320... ...
plane is shown in figure 12. After all had received their caloric stimulations, subjects were seated facing the leading bulkhead of the MRSSS (upon which the OGI target light is affixed)
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From page 321... ...
Just prior to "spindown," a response to the unexperienced head-turn direction was made. At the end of the 4 hours of dynamic exposure, the subjects received caloric stimulations as during the prespin portion of the test, after which they were released.
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From page 322... ...
No difference appears to exist between the stable or perturbating conditions, but a very consistent decrease is observed in the time of illusion when prerotation and postrotation values are compared. Six control subjects, tested without rotation but with a 4-hour interval between irrigations, did not show this decrease in OGI response duration.
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From page 323... ...
Left ear Right ear Prerotation Postrotation A Prerotation Postrotation A 8 rpm (steady) 115 61 -54 51 59 8 125 41 -84 136 29 -107 106 74 -32 121 58 -63 206 84 -122 115 83 -32 144 109 -33 139 64 -75 142 46 -96 100 52 -48 82 99 17 85 99 14 69 45 -14 94 36 -58 8 rpm with ±3° perturbation at O.I H/.
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From page 324... ...
8 rpm (±3° at 0.1 Hz) Prerotation Postrotation Prerotation Postrotation C,.-L L-CL C,-L L-CL C,.-L L-CL C,,-L L-CL £ 6.9 7.4 4.2 4.0 5.2 6.7 5.6 4.7 3.2 13 3.8 13 3.1 14 2.5 14 5.8 3.5 14 3.6 2.9 14 n ' 14 14 Total 14.3 8.2 11.9 10.3 Reduction, percent 41.3 13.5 Number of responses Extent of OGI response declines,2 percent 8 rpm (stable)
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From page 325... ...
The sinusoidal perturbations used in these studies with a range of vehicle angular velocity were as severe as have been predicted by the vehicle dynamicists. The three types of tests used represent a divergent approach that compared the pure passive motion of the subject to that of active head motions.
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From page 326... ...
A.: AND FRENCH, R S.: Adaptation to Prolonged Exposures in the Revolving Space Station Simulator.
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From page 327... ...
CORMACK, A.; AND CoucHMAN, C C.: Considerations of Crew Comfort in Relation to the Dynamics of Rotating Space Stations.
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From page 329... ...
SESSION X Chairman: LAWRENCE F DIETLEIN Manned Spacecraft Center, NASA
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