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Multidisciplinary Investigation of Truck Platooning

Altair-Bastian Schnepf, Christian Kehrer, Christoph Maeurer
  • Technical Paper
  • 2020-37-0028
To be published on 2020-06-23 by SAE International in United States
In the age of environmental challenges and with it, the demand for increasing energy efficiency of commercial vehicles, truck platooning is discussed as a promising approach. The idea is several trucks forming an automated convoy – with the lead truck sending out acceleration, braking and steering signals for the following trucks to react accordingly. The benefits address fuel savings, traffic capacity, safety requirements and convenience. In our study, we will motivate why platooning requires a multidisciplinary approach in the sense of connecting different modeling and simulation methods. The simulation topics covered are aerodynamic analysis, vehicle-to-vehicle (V2V) communication, radar antenna placement and virtual drive cycle test for the energetic evaluation of a truck platoon in comparison to a single truck. Aerodynamic analyses are conducted using a transient Lattice Boltzmann approach on GPUs capturing the complex vehicle wake interactions for different platooning distances with acceptable computational effort. Thereby, a generic truck convoy, consisting of three vehicles, is considered for distance intervals between 7 and 40 meters. From these computations for each vehicle look-up-tables are derived for interpolation…
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Wind Tunnel Test to Determine Pantograph Noise Contribution on a High-speed Train

Korea Railroad Research Institute-Heemin Noh
  • Technical Paper
  • 2020-01-1517
To be published on 2020-06-03 by SAE International in United States
In this study, we investigated the characteristics and the influence of the aero-acoustic noise generated from a pantograph using various experimental approaches in a wind tunnel. First, the noise generated at various flow velocities was measured and analyzed using a full-scale pantograph model. Then, the noise generated from the main position of the pantograph was derived using a microphone array attached to one side of a wind tunnel. The noise contributions of the main components of the pantograph were derived from the noise measurements obtained from a step-by-step disassembly of the full-scale model.Through this study, we have investigated the aero-acoustic noise contribution of the major components of a pantograph, and we have developed effective noise-reduction measures for the panhead collector.
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High Voltage Battery durability enhancement in electric mobility through 1D CAE

Tata Motors Ltd-Sambhaji Jaybhay, Kiran Kadam, Sangeet Kapoor
Tata Motors, Ltd.-Santosh Kumar Venu
  • Technical Paper
  • 2020-28-0013
To be published on 2020-04-30 by SAE International in United States
The public transport in India is gradually shifting towards electric mobility. Long range in electric mobility can be served with High voltage battery (HVB), but HVB can sustain for its designed life if it’s maintained within a specific operating temperature range. Appropriate battery thermal management through battery cooling system (BCS) is critical for vehicle range and battery durability This work focus on two aspects BCS sizing and coolant flow optimization in Electric bus. BCS modelling was done in 1D CAE by using KULI software from M/s Magna Steyr. The objective is to develop a model of battery cooling system in virtual environment to replicate the physical testing. Electric bus contain numerous battery packs and a complex piping in its cooling system. BCS sizing simulation was performed to keep the battery packs in operating temperature range. Iterations were carried out to maintain uniform flow at the battery packs as well as to sustain target coolant flow requirement in order to maintain thermal uniformity across the battery packs 1D simulation is vital when it comes to analyzing…
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Automated Driving System Safety: Miles for 95% Confidence in “Vision Zero”

Driving Safety Consulting LLC-Richard Allen Young
  • Technical Paper
  • 2020-01-1205
To be published on 2020-04-14 by SAE International in United States
Engineering reliability models from RAND, MobilEye, and Volvo concluded that billions of miles of on-road data were required to validate that the real-world fatality rate of an “Automated Driving System-equipped vehicle” (AV) fleet for an improvement over human-driven conventional vehicles (CV). RAND said 5 billion miles for 20%, MobileEye 30 billion for 99.9%, and Volvo 5 billion for 50% improvement. All these models used the Gaussian distribution, which is inaccurate for low crash numbers. The current study proposes a new epidemiologic method and criterion to validate real-world AV data with 95% confidence for zero to ten fatal crashes. The upper confidence limit (UL) of the AV fatal crash rate has to be lower than the CV fatal crash rate with 95% confidence. That criterion is met if the UL of the AV fatal crash incidence rate ratio estimate is below one. That UL was estimated using the mid-P exact method for calculating confidence limits for a dual Poisson process, using a one-tailed 95% confidence level. The required AV mileage was adjusted by trial and error…
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Cooperative Mandatory Lane Change for Connected Vehicles on Signalized Intersection Roads

Clemson University-Zhiyuan Du, Bin Xu, Pierluigi Pisu
  • Technical Paper
  • 2020-01-0889
To be published on 2020-04-14 by SAE International in United States
This paper presents a hierarchical control architecture to coordinate a group of connected vehicles on signalized intersection roads, where vehicles are allowed to change lane to follow a prescribed path. The proposed hierarchical control strategy consists of two control levels: a high level controller at the intersection and a decentralized low level controller in each car. In the hierarchical control architecture, the centralized intersection controller estimates the target velocity for each approaching connected vehicle to avoid red light stop based on the signal phase and timing (SPAT) information. Each connected vehicle as a decentralized controller utilizes model predictive control (MPC) to track the target velocity in a fuel efficient manner. The main objective in this paper is to consider mandatory lane changes. As in the realistic scenarios, vehicles are not required to drive in single lane. More specifically, they more likely change their lanes prior to signals. Hence, the vehicle decentralized controllers must prepare to cooperate with the vehicle that has a mandatory lane change request (host vehicle). The cooperative mandatory lane change is accomplished…
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Effects of a Probability-Based Green Light Optimized Speed Advisory on Dilemma Zone Exposure

Indiana Department of Transportation-James Sturdevant
Purdue University-Enrique Saldivar-Carranza, Howell Li, Woosung Kim, Jijo Mathew, Darcy Bullock
  • Technical Paper
  • 2020-01-0116
To be published on 2020-04-14 by SAE International in United States
Green Light Optimized Speed Advisory (GLOSA) systems have the objective of providing a recommended speed to arrive at a traffic signal during the green phase of the cycle. GLOSA has been shown to decrease travel time, fuel consumption, and carbon emissions; simultaneously, it has been demonstrated to increase driver and passenger comfort. Few studies have been conducted using historical cycle-by-cycle phase probabilities to assess the performance of a speed advisory capable of recommending a speed for various traffic signal operating modes (fixed-time, semi-actuated, and fully-actuated). In this study, a GLOSA system based on phase probability is proposed. The probability is calculated prior to each trip from a previous week’s, same time-of-day (TOD) and day-of-week (DOW) period, traffic signal controller high-resolution event data. By utilizing this advisory method, real-time communications from the vehicle to infrastructure (V2I) become unnecessary, eliminating data-loss related issues. The effects of three different advice approaches (conservative, balanced, and aggressive) on dilemma zone exposure are analyzed. Proof of concept is carried out by virtually driving through a test-route composed of an arterial that…
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In-Situ Measurement of Component Efficiency in Connected and Automated Hybrid-Electric Vehicles

Southwest Research Institute-Peter Lobato, Kyle Jonson, Sankar Rengarajan, Jayant Sarlashkar
  • Technical Paper
  • 2020-01-1284
To be published on 2020-04-14 by SAE International in United States
Connected and automated driving technology is known to improve real-world vehicle efficiency by considering information about the vehicle’s environment such as traffic conditions, traffic lights or road grade. This study shows how the powertrain of a hybrid-electric vehicle realizes those efficiency benefits by developing methods to directly measure transient real-time efficiency and power losses of the vehicle’s powertrain components through chassis-dynamometer testing. This study is a follow-on to SAE Technical Paper 2019-01-0116, Test Methodology to Quantify and Analyze Energy Consumption of Connected and Automated Vehicles, to understand the sources of efficiency gains resulting from connected and automated vehicle driving. A 2017 Toyota Prius Prime was instrumented to collect power measurements throughout its powertrain and driven over a specific driving schedule on a chassis dynamometer. The same driving schedule was then modified to simulate a connected and automated vehicle driving profile, and the sources of vehicle efficiency improvements are analyzed. While conventional powertrain components typically only have two sources and sinks of power, e.g. an input and output shaft, the components of modern hybrid-electric vehicles are…
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The Design of Safe-Reliable-Optimal Performance for Automated Driving Systems on Multiple Lanes with Merging Features

Honda Motor Co., Ltd.-Kaijiang Yu
  • Technical Paper
  • 2020-01-0122
To be published on 2020-04-14 by SAE International in United States
Safety function for automated driving systems including advanced driver assistance systems and autonomous vehicle systems is very important. Inside safety function, predictive judge sub-function should be designed with the consideration of more and more penetration of automated driving vehicles. This paper presents the design on multiple lanes with merging features based on the author's previous Patent JP2019-147944 using predictive time-head-way and time-to-collision maps. In the author's previous work (Model Predictive Control for Hybrid Electric Vehicle Platooning Using Slope Information-Published on IEEE Transactions on Intelligent Transportation Systems), a model predictive control framework was designed. Due to the difficulty to detail the sub-safety function deeply with merging features, few works are found to deal with sensor platforms focusing on rear side, and situations of merging lane side with the consideration of relative relation variations with other vehicles and road border markers. However, performance enhancement is needed assuring 100% safety-reliability-optimality and single-objectivity. Also, platforms of on-board sensors including side and rear view are needed to deal with false negative operations and false positive operations. The optimal operation line…
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Traffic Control Strategies for Congested Heterogeneous Multi-Vehicle Networks

University of North Carolina Charlotte-Pouria Karimi Shahri, Amir H. Ghasemi, Vahid Izadi
  • Technical Paper
  • 2020-01-0086
To be published on 2020-04-14 by SAE International in United States
The primary goal of this paper is to pioneer and develop robust and adaptive algorithms for controlling autonomous vehicles in heterogeneous networks with the aim of maximizing the performance (in terms of mobility) and minimizing variation in the network. While the fundamental approaches and models proposed in this research can be applied to any heterogeneous multi-agent system, we select heterogeneous traffic networks as a set-up for exploring the proposed research. We consider the heterogeneity in the system in the form of a mix of autonomous and human-driven vehicles (different levels of autonomous vehicle penetration). We propose a two-level hierarchical controller wherein the upper-level controller, an optimization problem using the concept of macroscopic fundamental diagram is formulated to deal with the traffic demand balance problem. At the lower level, using the microscopic models of the network, the control actions for each vehicle will be determined such that he optimal flow received from the upper-level controllers can be tracked.
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Utilization of vehicle connectivity for improved energy consumption of a speed harmonized cohort of vehicles.

Michigan Technological University-Christopher Morgan, Darrell Robinette, Pruthwiraj Santhosh, John Bloom-Edmonds
  • Technical Paper
  • 2020-01-0587
To be published on 2020-04-14 by SAE International in United States
Improving vehicle response through advanced knowledge of traffic behavior can lead to large improvements in energy consumption for the single isolated vehicle. This energy savings across multiple vehicles can even be larger if they travel together as a cohort in harmonization. Additionally, if the vehicles have enough information about their immediate path of travel, and other vehicles’ in that path (and their respective critical forward looking information), they can safely drive close enough to each other to share aerodynamic load. These energy savings can be upwards of multiple percentage points, and are dependent on several criteria. This analysis looks at criteria that contributes to energy savings for a cohort of vehicles in synchronous motion, as well as describes a study that allows for better understanding of the potential benefits of different types of cohorted vehicles in different platoon arrangements. The basis of this study is a precursor to developing a connected vehicle application that safely allows for fully controlled platooning on open highway for multi-destination vehicles. In this study, two types of light duty passenger…