Comparing time to collision and time headway as safety criteria

Khansari, Ehsan Ramezani; Nejad, Fereidoon Moghadas; Moogehi, Sina

doi:10.5505/pajes.2020.79837

Cited by 5 publications

(2 citation statements)

References 25 publications

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“…The simulation is performed over several iterations, and the TTC values are generated for each scenario using different input parameters for each scenario. As per the literature, there is no definite value for the TTC threshold to enable discrimination between safe and unsafe car-following situations [21]. According to a recent study, the threshold TTC varies from 1 to 3 s [22].…”

Section: Safetymentioning

confidence: 99%

Should Autonomous Vehicles Collaborate in a Complex Urban Environment or Not?

Malik,

Khan,

El-Sayed

et al. 2023

Smart Cities

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A specialized version of collaborative driving is convoy driving. It is referred to as the practice of driving more than one vehicle consecutively in the same lane with a small inter-vehicle distance, maintaining the same speed. Extensive research has been conducted on convoys of heavy-duty trucks on the highway; however, limited research has studied convoy driving in an urban environment. The complex dynamics of an urban environment require short-lived collaboration with varying numbers of vehicles rather than collaborating over hours. The motivation of this research is to investigate how convoy driving can be realized to address the challenges of an urban environment and achieve the benefits of autonomous driving such as reduced fuel consumption, travel time, improved safety, and ride comfort. In this work, the best-fitted coalitional game framework is utilized to formulate the convoy driving problem as a coalition formation game in an urban environment. A hypothesis is formulated that traveling in a coalition is more beneficial for a vehicle than traveling alone. In connection with this, a coalitional game and an all-comprehensive utility function are designed, modeled, and implemented to facilitate the formation of autonomous vehicle coalitions for convoy driving. Multiple solution concepts, such as the Shapley allocation, the Nucleolus, and the Core, are implemented to solve and analyze the proposed convoy driving game. Furthermore, several coalition formation strategies such as traveling mode selection, selecting optimal coalitions, and making decisions about coalition merging are developed to analyze the behavior of the vehicles. In addition to this, extensive numerical experiments with different settings are conducted to evaluate and validate the performance of the proposed study. The experimental results proved the hypothesis that traveling in a convoy is significantly more beneficial than traveling alone. We conclude that traveling in a convoy is beneficial for coalition sizes of two to four vehicles with an inter-vehicle spacing of less than 4 m considering the limitations of an urban environment. Traveling in a coalition allows vehicles to save on fuel, minimize travel time and enhance safety and comfort. Furthermore, the findings of this research state that achieving the enormous benefits of traveling in a coalition requires finding the right balance between inter-vehicle distance and coalition size. In the future, we plan to extend this work by studying the evolving dynamics of the coalitions and the environment.

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Section: Safetymentioning

confidence: 99%

Should Autonomous Vehicles Collaborate in a Complex Urban Environment or Not?

Malik,

Khan,

El-Sayed

et al. 2023

Smart Cities

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“…Ramezani ve diğ. [15] taşıtlar arasındaki mesafeyi korumak için gerekli takip ve frenleme zaman aralıklarını incelemiştir. Kazanın etkilerini minimize etmek için frenleme zamanının öneminden ve gelecek taşıt modellerinde bunların dikkate alınabileceğinden bahsetmiştir.…”

Section: Introductionunclassified

Improving the load distribution in the automobile front collision zone by adding 'S' shaped curved collision rail

Bilbay,

Reis,

Gülçimen Çakan

et al. 2023

Pamukkale J Eng Sci

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Bu çalışmada, "S" şeklinde bir çarpışma kolu ile güçlendirilmiş, aracın ön çarpışma bölgesinin performansı, klasik düz çarpışma kolununki ile karşılaştırılmıştır. Taşıtlarda çok yöne ve sürekliliğe sahip yük yollarını çıkarmak amacıyla ön taraftan çarpma senaryosu Hyperworks -Optistruct yazılımı ile modeli oluşturulmuş ve aracın topoloji optimizasyonu yapılmıştır. Çıkarılan yük yolları kullanılarak aracın ön çarpışma bölgesinde yer alan komponentler tasarlanmıştır. Ön çarpışma bölgesi komponentlerinin malzeme özellikleri, bağlantı/temas bölgeleri ve eleman ağ yapılarının oluşturulmasnda Altair Hypermesh yazılımı kullanılmış ve böylece ön işlem adımı tamamlanmıştır. Klasik düz çarpışma koluna sahip ön çarpışma bölgesi ile "S" şeklindeki çarpışma koluyla güçlenedirilmiş ön çarpışma bölgesini karşılaştırmak amacıyla iki farklı çarpışma bölgesi modeli kullanılmış ve analizlerin çözümü için Abaqus çözücüsü kullanılmıştır. Her bir simülasyondan çarpışma bölgesi komponentleri tarafından sönümlenen enerji miktarı, çarpışma bölgesinde meydana gelen toplam deplasman, çarpışma sonucu yolcu kabinine iletilen yükler ve çarpışma kuvvetinin verimliliği (CFE) sonuç olarak elde edilmiştir.In this study, the performance of the front collision zone of the vehicle, reinforced with an S-shaped front collision rail, was compared to that of the classic straight front collision rail. In order to create a safe living cage in automobiles, half vehicle model was used and the collision performances of two different front collision zone models were compared. Torsion, bending and frontal impact scenarios were created with Hyperworks-Optistruct software to obtain versatile and continuous load paths in the vehicle. Vehicle front collision zone elements were designed with Siemens NX software based on the resulting load paths. Altair Hypermesh software was used to create the material properties, connection/contact zones and element mesh structures of the front collision zone components, and thus the preprocessing step was completed. Two different collision zone models were used to compare the collision zone with the classic arm and the one reinforced with the "S" shaped collision arm. The amount of energy absorbed by the collision zone components, the total displacement in the collision zone, the loads transmitted to the passenger cabin and the efficiency of the collision force (CFE) were obtained from each simulation.

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