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Heavy-duty aerodynamic testing for CO2 certification: A methodology comparison

Intl. Council on Clean Transportation-J. Felipe Rodriguez, Oscar Delgado
University of Technology Graz-Martin Rexeis, Martin Röck
  • Technical Paper
  • 2019-01-0649
To be published on 2019-04-02 by SAE International in United States
Air drag testing is a key component of the CO2 certification schemes for heavy-duty vehicles around the world. This paper presents and compares the regulatory approaches for measuring the air drag coefficient of heavy-duty vehicles in Europe, which uses a constant-speed test, and in the United States and Canada, which use a coastdown test. Two European trucks and one North American truck were tested using the constant-speed and coastdown methods. When corrected to zero yaw angle, a difference of over 10% was observed in the measured drag coefficients from the US coastdown procedure and the EU constant-speed test. The differences in the measured air drag coefficient can be attributed to the data post-processing required by each methodology, the assumptions in the speed-dependence of the tire rolling resistance, unaccounted frictional losses in the differential axle and transmission, as well as the behavior of the automated manual transmission during the coastdown run.

Driver’s response prediction using Naturalistic Data Set

Ohio State Univ-Dennis Guenther
Ohio State University-Venkata Raghava Ravi Lanka
  • Technical Paper
  • 2019-01-0128
To be published on 2019-04-02 by SAE International in United States
Evaluating the safety of Autonomous Vehicles (AV) is a challenging problem, especially in traffic conditions involving dynamic interactions. A thorough evaluation of the vehicle's decisions at all possible critical scenarios is necessary for estimating and validating its safety. However, predicting the response of the vehicle to dynamic traffic conditions can be the first step in the complex problem of understanding vehicle's behavior. This predicted response of the vehicle can be used in validating vehicle's safety. In this paper, models based on Machine Learning were explored for predicting and classifying driver's response. The Naturalistic Driving Study dataset (NDS), which is part of the Strategic Highway Research Program-2 (SHRP2) was used for training and validating these Machine Learning models. Various popular Machine Learning Algorithms were used for classifying and predicting driver's response, such as Extremely Randomized Trees and Gaussian Mixture Model based Hidden Markov Model, which are widely used in multiple domains. For classifying driver's response, longitudinal acceleration vs lateral acceleration plot (Ax-Ay plot) was divided into nine different classes and selected Machine Learning models were trained…

PHEV Real World Driving Cycle and Energy and Fuel Consumption Reduction Potential for Connected and Automated Vehicles

Michigan Technological Univ.-Darrell Robinette, Eric Kostreva, Alexandra Krisztian, Anthony Lackey, Christopher Morgan, Joshua Orlando, Neeraj Rama
  • Technical Paper
  • 2019-01-0307
To be published on 2019-04-02 by SAE International in United States
This paper presents real world driving energy and fuel consumption results for the second-generation Chevrolet Volt plug-in hybrid electric vehicle (PHEV). A drive cycle, local to Michigan Technological University, was designed to mimic urban and highway driving test cycles in terms of distance, transients and average velocity, but with significant elevation changes to establish an energy intensive real world driving cycle for assessing potential energy savings for connected and automated vehicle control. The investigation began by establishing baseline and repeatability of energy consumption at various battery states of charges. It was determined that drive cycle energy consumption under a randomized set of boundary conditions varied within 3.4% of mean energy consumption regardless of initial battery state of charge. After completing 30 baseline drive cycles, a design for six sigma (DFSS) L18 array was designed to look at sensitivity of a range of parameters to energy consumption as related to connected and automated vehicles to target highest return on engineering development effort. The parameters explored in the DFSS array that showed the most sensitivity, in order…

CATARC New Type Drivetrain NVH Test Facility

CATARC-Hui Gao, Yongchao Wang, Dong Wang
Jilin University-HongBin Yin
  • Technical Paper
  • 2019-01-0788
To be published on 2019-04-02 by SAE International in United States
As the most intuitive performance of users, NVH performance is one of the comprehensive indicators to evaluate the manufacturing standard of the whole vehicle. About one-third of the vehicle complaint are related to NVH performance. As a core component of the vehicle, the NVH characteristics of the drivetrain have a significant impact on vehicle comfort . How to reliably and stably reproduce the specific condition of the whole vehicle through the test method, and obtain the highly consistent objective data for analyzing and improving the NVH characteristics of the drivetrain, which is of great significance in engineering. For this purpose, China Automotive Technology Research Center Co., Ltd. (CATARC) designed and built a unparalleled drivetrain NVH test facility, which consists of five dynamometers. Test specimens such as powertrain, transmission, and rear axle can be mounted to the facility. The structure is not limited to the horizontal/vertical, front/rear drive/four-wheel drive structure, or even a whole vehicle. Due to the battery simulator, the above specimens of the fuel vehicle, hybrid vehicle and electric vehicle can be satisfied. The…

Constructing a Concept Vehicle Structure Optimized for Crashworthiness

Dassault Systemes Simulia Corp-Shawn Freeman, Fabien Letailleur
Dassault Systemes Simulia Corp.-Yangwook Choi
  • Technical Paper
  • 2019-01-0613
To be published on 2019-04-02 by SAE International in United States
Multi-disciplinary optimization (MDO) of a vehicle structure at the earliest stages of design is critical as OEMs are pressed to reduce the design time to respond to various demands from market. MDO for the three essential areas of performance of the vehicle structure (NVH, Crash, and Durability) needs the throughput for each of the key disciplines to be approximately in the same range of turn-around time. However, crashworthiness simulation typically takes significantly longer than the others; making it difficult to include crashworthiness in the MDO. There have been many approaches to address crash simulation in a shorter time. Lumped mass-spring method is one of the approaches but has not been widely accepted since it did not replicate the crash behavior accurately and it is hard to convert the results into real design of the structural components. In the paper, a workflow is presented to combine the lumped mass-spring method with paramet-ric optimization to provide solutions to the challenges mentioned.

Experiment Studies of Charging Strategy for Lithium-ion Batteries

Xuezhe Wei
Tongji Univ-Pei Yu, Haifeng Dai
  • Technical Paper
  • 2019-01-0792
To be published on 2019-04-02 by SAE International in United States
Regarding the lithium-ion batteries used in the electric vehicle, charging time and charging efficiency are the concern of the public. In this paper, a lot of experiments were conducted to investigate the common charging strategies, including the CC-CV (constant current-constant voltage) charging and the pulse current charging, for the LiFepO4 batteries, which are still widely used in commercial vehicles. Charging temperature and the charging current in the CC phase are the main influence factors to be studied for the CC-CV charging strategy, and the contribution of CC phase and CV phase to the whole charging is analyzed from three aspects, including the time percent, charging energy efficiency and the capacity of battery at different temperatures and charging current.Regarding the pulse charging strategy, the pulse frequency is determined from the perspective of energy loss, then the experiments for pulse charging with different pulse mode, different duty cycle, as well as different charging temperature and charging current were conducted to study the characteristic of pulse charging.In order to eliminate the battery polarization, we optimized the charging current…

Evaluation of Emissions from Light Duty Trucks with and without the Use of a Gasoline Particulate Filter

Environment and Climate Change Canada-Fadi Araji, Jonathan Stokes
  • Technical Paper
  • 2019-01-0971
To be published on 2019-04-02 by SAE International in United States
The goal of this study was to investigate the emission impacts of replacing the OEM three way catalyst on light duty trucks using various, commercially available, gasoline particulate filter (GPF) configurations. The three test vehicles were; a Port Fuel Injection (PFI) PFI_1 and two Gasoline Direct Injection (GDI) GDI_1 and GDI_2. The testing of these vehicles was conducted on a chassis dynamometer in a controlled test cell environment at two temperatures (25 °C and -7 °C) using the Federal Test Procedure (FTP-75) and the US06 test procedure. All three vehicles were tested in stock OEM configuration followed by testing PFI_1 and GDI_1 with a non-catalyzed GPF and GDI_2 with a catalyzed GPF. GDI_2 was also tested on-road using a portable emissions measurement system (PEMS) with and without the use of the catalyzed GPF. Results for the non-catalyzed GPF configuration on PFI_1 and GDI_1 showed a decrease in Total Particulate Matter (TPM) at both standard and cold temperatures, with the biggest decrease being 89.3% for GDI_1 during the FTP-75 at 25 °C. An increase in NOx…

Effect of Turbulence-Chemistry Interaction on Spray Combustion: a Large Eddy Simulation Study

Dalian University of Technology-Ming Jia
Tianjin University-Junqian Cai, Tianyou Wang, Kai Sun, Zhen Lu, Gang Xiao, Shiquan Shen
  • Technical Paper
  • 2019-01-0203
To be published on 2019-04-02 by SAE International in United States
Although turbulence plays a critical role in engines operated within low temperature combustion (LTC) regime, its interaction with chemistry on auto-ignition at low-ambient-temperature and lean-oxygen conditions remains inadequately understood. Therefore, it is worthwhile taking turbulence-chemistry interaction (TCI) into consideration in LTC engine simulation by employing advanced combustion models. In the present study, large eddy simulation (LES) coupled with linear eddy model (LEM) is performed to simulate the ignition process in n-heptane spray under engine-relevant conditions, known as Spray H. With LES, more details about unsteady spray flame could be captured compared to Reynolds-averaged Navier-Stokes equations (RANS). With LEM approach, both scalar fluctuation and turbulent mixing on sub-grid level are captured, accounting for the TCI. A skeletal mechanism is adopted in this numerical simulation, including 41 species and 124 reactions. Validations is carried out and numerical results show good agreement with experimental data. It is found that, Damköhler number (Da) at the onset of high temperature reaction evidently decreases as ambient temperature and oxygen reduces. Consequently, combustion mode varies from flamelet regime to slow chemistry regime,…

Automated Vehicle Disengagement Reaction Time Compared to Human Reaction Times in Both Automobile and Motorcycle Operation

Dynamic Analysis Group LLC-Jeffrey T. Dinges, Nicholas J. Durisek
  • Technical Paper
  • 2019-01-1010
To be published on 2019-04-02 by SAE International in United States
Autonomous Vehicle Disengagement Reports have been published by the California Department of Motor Vehicles since 2015. Some of the autonomous control system manufacturers and vehicle manufacturers provide information that includes the time that it takes for a human driver to take manual control of the vehicle when reporting on vehicle disengagements. This study compares the reported autonomous vehicle operation disengagement reaction time to field literature in testing and experimentation on human reaction times for both automobile and motorcycle operation. The study will address the types of autonomous vehicle disengagements that occurred during the collection along with the understood conditions that surround the disengagement. It will also address how autonomous vehicle disengagements and general human perception and reaction performance influences autonomous vehicle operation.

Comparison of Particulate Emissions of a Range Extended Electric Vehicle under Different Energy Management Strategies

Tongji Univ-Yaxin Wang, Diming Lou, Ning Xu, Piqiang Tan, Zhiyuan Hu
  • Technical Paper
  • 2019-01-1189
To be published on 2019-04-02 by SAE International in United States
Range extended electric vehicles achieve significant reductions in fuel consumption by employing as an energy source a small displacement combustion engine that is optimized for high efficiency at one, or a few, operating points. The present paper examines the impact of various energy management strategies on the particulate emissions from the auxiliary power unit (APU) of a range extended electric bus, including optimized auxiliary power unit (APU) on/off strategy, single-point strategy, two-point strategy, power-following strategy and equivalent fuel consumption minimization strategy (ECMS). In addition, this paper also compares the particulate emissions of single energy storage system and composite energy storage system on single-point energy management strategy. The main conclusions in this paper are as follows: After optimizing the APU on/off strategy, the APU starts and stops frequently to make the cylinder temperature relatively low, which results in the reductions of both the particle mass (PM) and the particle number (PN). The application of two-point strategy and power-following strategy maximizes the output power of high load, and then the particulate emission presents significant increasing. With the…