Добірка наукової літератури з теми "Seat swiveling"

A new concept in the interior design of autonomous vehicles is rotatable or swivelling seats that allow people sitting in the front row to rotate their seats and face backwards. In the current study, we used a take-over request task conducted in a fixed-based driving simulator to compare two conditions, driver front-facing and rear-facing. Thirty-six adult drivers participated in the experiment using a within-subject design with take-over time budget varied. Take-over reaction time, remaining action time, crash, situation awareness and trust in automation were measured. Repeated measures ANOVA and Generalized Linear Mixed Model were conducted to analyze the results. The results showed that the rear-facing configuration led to longer take-over reaction time (on average 1.56 s longer than front-facing, p < 0.001), but it caused drivers to intervene faster after they turned back their seat in comparison to the traditional front-facing configuration. Situation awareness in both front-facing and rear-facing autonomous driving conditions were significantly lower (p < 0.001) than the manual driving condition, but there was no significant difference between the two autonomous driving conditions (p = 1.000). There was no significant difference of automation trust between front-facing and rear-facing conditions (p = 0.166). The current study showed that in a fixed-based simulator representing a conditionally autonomous car, when using the rear-facing driver seat configuration (where participants rotated the seat by themselves), participants had longer take-over reaction time overall due to physical turning, but they intervened faster after they turned back their seat for take-over response in comparison to the traditional front-facing seat configuration. This behavioral change might be at the cost of reduced take-over response quality. Crash rate was not significantly different in the current laboratory study (overall the average rate of crash was 11%). A limitation of the current study is that the driving simulator does not support other measures of take-over request (TOR) quality such as minimal time to collision and maximum magnitude of acceleration. Based on the current study, future studies are needed to further examine the effect of rotatable seat configurations with more detailed analysis of both TOR speed and quality measures as well as in real world driving conditions for better understanding of their safety implications.

To improve the low viscosity and poor lubrication characteristics of high-water-based hydraulic liquid, the abrasion and leakage problems in hydraulic components need to be addressed. In a high water-based hydraulic motor with self-balanced distribution valve (HWBHM-SDV), there are two key friction pairs: the piston-crankshaft pair and piston-swivelling-cylinder (PSC) pair. To study the working performance of the PSC pair in HWBHM-SDV, we firstly designed the structural parameters. We found that, within the working speed 0–100 rpm, the leakage in the PSC pair is mainly caused by pressure-gradient flow, and the influence of the seal will not be significant when the seal length is 24 mm. Then, the friction coefficients of different matching materials were tested. It was found that the friction coefficient of 316L stainless steel with OVINO-GIC (OVINO-graphite intercalated compound) coating (316L-GIC)/PEEK reinforced with 30% carbon fibre (PEEK-30CF) is about 0.02~0.04, and the friction coefficient of 316L-GIC/316L-GIC is about 0.05–0.07. Finally, the influences of factors (clearance, temperature, pressure, and material) on leakage performance were analysed based on an orthogonal test method considering fluid-structure interaction. It was found that clearance has the most significant influence on leakage, followed by pressure and liquid temperature, and the difference between matching materials 316L-GIC/316L-GIC and 316L-GIC/PEEK-30CF is insignificant when the clearance is less than 8 μm and the working pressure is less than 10 MPa. Moreover, the difference in volume efficiency loss between theoretical analysis and calculated result considering fluid-structure interaction increases with the increase of working pressure and working speed. To ensure good working performance of a PSC pair, matching materials 316L-GIC/PEEK-30CF could be selected for pressures below 15 MPa, while 316L-GIC/316L-GIC could be used at 28 MPa.

Des efforts de recherche et développement considérables portent actuellement sur des véhicules automatisés qui pourraient libérer les conducteurs des tâches de conduite. Le siège et l’intérieur de l’habitacle pourraient être modifiés pour mieux accommoder les activités autres que la conduite, telle que dormir, lire et travailler etc. Cependant, même si un grand niveau de sécurité est attendu pour ces futurs véhicules, des accidents continueront à survenir. Les dispositifs de protection actuels sont conçus pour une position de conduite. Ils pourraient nécessiter des modifications afin de conserver le niveau de protection actuel pour de nouvelles positions d’occupant. Cette thèse vise à identifier les risques et les opportunités en termes de protection de l’occupant associés à de nouvelles positions pouvant être introduites avec les véhicules automatisés. Sur le plan méthodologique, elle s’est largement appuyée sur les modèles humains numériques pour le choc qui se sont révélés comme un outil pertinent d'évaluation du risque. Une attention particulière a été portée à l'évaluation de la validité des modèles après repositionnement. Les travaux ont permis de mieux comprendre les mécanismes de retenue dans des positions semi-allongées en choc frontal. Ces positions apparaissent critiques avec une retenue délicate du bassin ou un chargement de la colonne lombaire selon l’angle d’assise. Une sensibilité importante à la position initiale du bassin a également été observée. Ces résultats pourront être utilisés afin d’aider à concevoir et à évaluer des nouveaux dispositifs de retenue. Afin de mieux connaître la posture de confort dans ces positions inclinées, une étude expérimentale a été réalisée à l’aide d’un siège multi-réglable. Ces expérimentations ont permis d’une part d‘identifier des configurations de siège de confort, et d’autre part d’établir les relations entre ces configurations de siège et la position du squelette interne, et en particulier celle du bassin. Ces résultats pourront notamment aider au positionnement des occupants lors d’essais physiques ou numériques. Dans l’ensemble, ces travaux montrent l’interaction forte entre le confort et la sécurité pour la conception de nouveaux habitacles automobiles
Considerable research and development efforts are currently focused on automated vehicles that could free drivers from driving tasks and allow them to perform new activities (e.g. working, sleeping). Such activities would benefit from new seating configurations. However, even if a high level of safety is expected for these future vehicles, accidents will continue to occur. Current protective devices are designed for a driving position. They may require modifications to maintain the current level of protection for new occupant positions. This thesis aims to identify the risks and opportunities in terms of occupant protection associated with new positions that could appear with automated vehicles. The analyses used digital human models for applied traffic safety which have proven to be a relevant risk assessment tool. Particular attention was paid to assessing the validity of the models after repositioning. The work provided a better understanding of the restraint mechanisms in reclined configurations during a frontal impact. These positions appear to be critical with a difficult restraint of the pelvis or loading of the lumbar spine depending on the seat angle. The occupant response was also significantly affected by the initial position of the pelvis. These results can be used to help design and evaluate new restraint systems. In order to better understand the comfortable position in these reclined configurations, an experimental study was carried out using a multi-adjustable seat. These experiments enabled, on the one hand, to identify the comfort seat configurations, and on the other hand to establish the relationships between these seat configurations and the position of the internal skeleton and in particular for the pelvis. These results can in particular help the positioning of occupants during physical or digital tests. Overall, this work shows the strong interaction between comfort and safety for the design of new passenger cars

The Milankovitch or astronomical theory of paleoclimates relates climatic variation to the amount of solar energy available at the Earth's surface. The theory helps explain periodic, climatically related phenomena such as the Pleistocene ice ages. Identification of Milankovitch cyclicity within sediments demonstrates the influence of climate on sedimentation patterns and creates a time frame for the estimation of basin subsidence rates. Spectral analysis of deep sea and ice cores indicates periodic climatic fluctuations during Tertiary and Quaternary times. These fluctuations are strongly cyclical with low frequencies centered at periods around 400 ka and 100 ka together with shorter periodic components of approximately 41 and 21 ka. Lower frequencies reflect eccentricity of the Earth's orbit; 41- and 21-ka components are associated with periodic changes in the tilt of the Earth's axis and the precession of the equinoxes. Astronomically forced glacial eustasy results in distinct stratigraphic units or parasequences of widespread extent. Milankovitch band parasequences occur in both carbonate and clastic shelf systems, including cyclothemic Upper Paleozoic successions of North America. During the 1920's and 30's the Serbian mathematician Milutin Milankovitch studied cyclical variations in three elements of the Earth-Sun geometry: eccentricity, precession, and obliquity, and was able to calculate the Earth's solar radiation history for the past 650 ka (Milankovitch, 1969). Berger (1978, 1980) accurately determined the periodicities of the three orbital variations. Eccentricity—The Earth's orbit around the Sun is an ellipse; this results in the seasons. The eccentricity of the Earth's orbit periodically departs further from a circle and then reverts to almost true circularity. Periodicities are located around 413, 95, 123, and 100 ka. Secondary peaks appear to be located around 50 and 53 ka. There are further important periodicities at 1.23, 2.04, and 3.4 ma (Schwarzacher, 1991). Precession—Precession refers to variation in time of year at which the Earth is nearest the Sun (perihelion). This variation is caused by the Earth wobbling like a top and swiveling on its axis. Periodicities of 23,000, 22,400, 18,980, and 19,610 yr are recognized and often simplified to two periods of 19 and 23 ka. Secondary peaks are also located around 30 and 15 ka.