Underestimation of self-tilt increases in reduced gravity conditions

2021 ◽  
pp. 1-8
Author(s):  
Arjan J. H. Meskers ◽  
Mark M. J. Houben ◽  
Helena J. M. Pennings ◽  
Gilles Clément ◽  
Eric Groen
Keyword(s):  
Parabolic Flight ◽  
Head Tilt ◽  
Body Axis ◽  
Reduced Gravity ◽  
Head Mounted Display ◽  
Longitudinal Body Axis ◽  
Partial Gravity ◽  
Visual Vertical ◽  
Regression Slopes ◽  
Head Roll

BACKGROUND: During large angles of self-tilt in the roll plane on Earth, measurements of the subjective visual vertical (SVV) in the dark show a bias towards the longitudinal body axis, reflecting a systematic underestimation of self-tilt. OBJECTIVE: This study tested the hypothesis that self-tilt is underestimated in partial gravity conditions, and more so at lower gravity levels. METHODS: The SVV was measured in parabolic flight at three partial gravity levels: 0.25, 0.50, and 0.75 g. Self-tilt was varied amongst 0, 15, 30, and 45 deg, using a tiltable seat. The participants indicated their SVV by setting a linear array of dots projected inside a head mounted display to the perceived vertical. The angles of participants’ body and head roll tilt relative to the gravito-inertial vertical were measured by two separate inertial measurement units. RESULTS: Data on six participants were collected. Per G-level, a regression analysis was performed with SVV setting as dependent variable and head tilt as independent variable. The latter was used instead of chair tilt, because not all the participants’ heads were aligned with their bodies. The estimated regression slopes significantly decreased with smaller G-levels, reflecting an increased bias of the SVV towards the longitudinal body axis. On average, the regression slopes were 0.95 (±0.38) at 0.75 g; 0.84 (±0.22) at 0.5 g; and 0.63 (±0.33) at 0.25 g. CONCLUSIONS: The results of this study show that reduced gravity conditions lead to increased underestimation of roll self-tilt.

Perception of longitudinal body axis in microgravity during parabolic flight

2007 ◽  
Vol 413 (2) ◽  
pp. 150-153 ◽  
Author(s):  
Gilles Clément ◽  
Tonje N. Arnesen ◽  
Morten H. Olsen ◽  
Bruno Sylvestre
Keyword(s):  
Parabolic Flight ◽  
Body Axis ◽  
Longitudinal Body Axis

Postural adjustment as a function of scene orientation

2021 ◽  
Author(s):  
Kanon Fujimoto ◽  
Hiroshi Ashida
Keyword(s):  
Postural Control ◽  
Visual Cues ◽  
Head Tilt ◽  
Visual Orientation ◽  
Postural Adjustment ◽  
Postural Response ◽  
Everyday Objects ◽  
Head Mounted Display ◽  
Visual Vertical ◽  
Vector Sum

Visual orientation plays an important role in postural control, but the specific characteristics of postural response to orientation remain unknown. In this study, we investigated the relationship between postural response and the subjective visual vertical (SVV) as a function of scene orientation. We presented a virtual room including everyday objects through a head mounted display and measured head tilt. The room orientation varied from 165° left to 180° right in 15° increments. In a separate session, we also conducted a rod adjustment task to record the participant’s SVV in the tilted room. We applied a weighted vector sum model to head tilt and SVV error, and obtained the weight of three visual cues to orientation: frame, horizon and polarity cues. We found substantial contributions of all visual cues to head tilt and SVV error. For SVV error, frame cues made the largest contribution, whereas polarity contribution made the smallest. Head tilt tended to follow a similar pattern to SVV error, but the pattern was unclear. These findings suggest that multiple visual cues to orientation are involved in postural control, and imply different representations of environmental coordinates across postural control and verticality perception.

scholarly journals Antihysteresis of perceived longitudinal body axis during continuous quasi-static whole-body rotation in the earth-vertical roll plane

2011 ◽  
Vol 209 (3) ◽  
pp. 443-454
Author(s):  
M. Tatalias ◽  
C. J. Bockisch ◽  
G. Bertolini ◽  
D. Straumann ◽  
A. Palla
Keyword(s):  
Body Axis ◽  
Whole Body ◽  
Body Rotation ◽  
Longitudinal Body Axis ◽  
Vertical Roll ◽  
The Earth

Reduced-Gravity Human Factors Research with Aircraft

1969 ◽  
Vol 11 (5) ◽  
pp. 463-471 ◽  
Author(s):  
Michael J. Moran
Keyword(s):  
Human Factors ◽  
Space Flight ◽  
Gravity Data ◽  
Parabolic Flight ◽  
Gravity Level ◽  
Reduced Gravity ◽  
Low Gravity ◽  
Simulation Techniques ◽  
Space Experiments ◽  
Actual Space

Human factors in a low-gravity environment became important with the beginning of manned space flight programs. The costs and dangers associated with actual space experiments necessitated the development of reduced-gravity simulation techniques. Since parabolic flight is the only way to produce approximately the same physical conditions as orbital space flight, it is the only technique acceptable for many human factors studies. However, the shortness of periods at the desired gravity level and the high gravity levels of the pre- and post-parabola flight compromise the effectiveness of the technique. In spite of its faults, this technique has been used to produce many meaningful studies. These studies have done much to increase our limited knowledge of reduced-gravity human factors. It appears that this technique will continue to be a main source of low-gravity data, until the era of manned orbiting laboratories.

Human Factors Review of Space Habitat Feature Requirements

2017 ◽  
Vol 61 (1) ◽  
pp. 62-62
Author(s):  
James Flores ◽  
Farzan Sasangohar
Keyword(s):  
Parabolic Flight ◽  
Vertical Displacement ◽  
Human Motion ◽  
The Moon ◽  
Friction Forces ◽  
Transition Speed ◽  
Human Scale ◽  
Partial Gravity ◽  
Ceiling Height ◽  
Reaction Forces

Sending humans to other planets requires an understanding of the effects of the partial gravity on human motion before attempting to design or build buildings or plan mission tasks. Architecture is the most basic example of human-centered design as everything in a building is to “human” scale. While some modern studies (e.g., Capps, et. al, 1989) reference a study which looked at the humans and forces for the Moon landing (Hewes et. al, 1966), this study was never correlated with the actual lunar data and has many erroneous assumptions. Previous work in Biomechanics was reviewed and the elements of physics required to analyze human motion in partial gravity was analyzed and several basic questions were generated. Included in these studies are NASA studies which look at parabolic flight and apparatus to simulate the effects of partial gravity (NASA/TM-2010-216139, 2010). The key part of physics that drives the changes in human motion is the fact that the momentum of a human or object in motion remains the same while gravity reduces the normal forces on the feet which in turn cause a reduction in the friction reaction forces available for maneuvering or stopping. The study investigates design of several building features for space architecture. These include: Ceiling Height, Door Size, Railing Height, Stairs, Ladders, and Ramps. The first of these the ceiling height relates to the question of does a person “bounce” when they walk in partial gravity. Typical ceilings on Earth range from 2.44 m (8 feet) to 3.05 m (10 feet) Studies of walk to run transition speed for partial gravity were reviewed and they measured the vertical displacement of the hip. This measurement varied by less than 1 cm and correlated to a minimal head height change. Door sizes and railing heights related to the height of 99th percentile humans projected to the year of launch to Mars or the Moon and also included spinal growth caused by 0 g transit. These projections do lead to a taller door opening (25 cm) and raised railing (14.3 cm) as compared to earth. Stairs and ladders both ended up being related to joint angles and human preferences such that they remain the same as on Earth. Chair heights which also relate to counter heights were looked at by reviewing studies of the sit-to-stand motion and comparing the foot and buttocks reaction forces to the friction forces available on Mars and the Moon verses Earth standard. This leads to a recommendation to use Pub height chairs and counters. Flooring and ramps required scaling and also calculating equivalency values to make comparisons. It was determined that the required friction when scaled to Mars would be possible with fairly standard flooring materials. The Lunar case however, would require a combination of high friction flooring and training for nominal movement. To analyze ramps independent calculations were used for friction requirements and then correlated to a study of emergency personnel pushing a trolley with a patient up or down a ramp. Both these methods correlated to an extremely shallow 2.86 degrees (slope 1 in 20) ramp being possible on Mars and ramps not being usable on the Moon. Based on these factors it is recommended that many of features follow standards used on earth and that only the required changes be made such that the habitation resemble Earth structures as much as possible. In addition, Astronaut training should incorporate these factors into their procedures.

Pool Boiling of n-Pentane, CFC-113, and Water Under Reduced Gravity: Parabolic Flight Experiments With a Transparent Heater

1995 ◽  
Vol 117 (2) ◽  
pp. 408-417 ◽  
Author(s):  
T. Oka ◽  
Y. Abe ◽  
Y. H. Mori ◽  
A. Nagashima
Keyword(s):  
Heat Transfer ◽  
Parabolic Flight ◽  
Pool Boiling ◽  
Glass Plate ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Rear Side ◽  
Heater Surface ◽  
Reduced Gravity ◽  
Liquid Behavior

A series of pool boiling experiments have been conducted under reduced gravity condition (the order of 10−2 times the terrestrial gravity) available in an aircraft taking parabolic flight. A transparent resistant heater, a transparent indium oxide film plated on a glass plate, was employed so that the vapor/liquid behavior interacting with the heater surface could be observed from the rear side of the heater simultaneously with the side view of vapor bubbles above the heater surface. The experiments were performed for three different fluids—n-pentane, CFC-113, and water—under subcooled conditions. The critical heat fluxes for both n-pentane and CFC-113 under the reduced gravity were lowered to about 40 percent of the corresponding terrestrial values. Although the heat transfer characteristics in a low heat flux nucleate boiling regime for both n-pentane and CFC-113 showed no more than a slight change with the reduction in gravity, a significant heat transfer deterioration was noted with water in the reduced gravity boiling. The observation from the rear side of the heater suggested that this particular difference in the gravity dependency of heat transfer was ascribed to a considerable difference, between the organic fluids and water, in the behavior of attachment to the heater surface of the bubbles grown up, while the behavior of attachment must depend on the surface tension of each fluid and the wettability of the heater surface with the fluid.

Head tilt is pronounced after an ipsilateral head roll in patients with vestibular schwannoma

2013 ◽  
Vol 271 (6) ◽  
pp. 1791-1796
Author(s):  
Topi Jutila ◽  
Heikki Aalto ◽  
Timo P. Hirvonen
Keyword(s):  
Vestibular Schwannoma ◽  
Head Tilt ◽  
Head Roll
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