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Gear Shift Pattern Optimization for Best Fuel Economy, Performance and Emissions

Chidhanand S.
Mahindra & Mahindra, Ltd.-Lemuel Paulraj, Saravanan Muthiah
  • Technical Paper
  • 2020-01-1280
To be published on 2020-04-14 by SAE International in United States
As the FTP-75 drive cycle does not have a prescribed gear shift pattern, automotive OEMs have the flexibility to design. Conventionally, gear shift pattern was formulated based on trial and error method, typically with 10 to 12 iterations on chassis dynamometer. It was a time consuming (i.e. ~ 3 to 4 months) and expensive process. This approach led to declaring poor fuel economy (FE). A simulation procedure was required to generate a gear shift pattern that gives optimal trade-off amongst conflicting objectives (FE, performance and emissions). As a result, a simulation tool was developed in MATLAB to generate an optimum gear shift pattern. Three different SUV/UV models were used as test vehicles in this study. Chassis dyno testing was conducted, and data was collected using the base and optimized gear shift patterns. Dyno test results with optimized gear shift pattern showed FE improvement of ~ 4 to 5% while retaining the NOx margin well above engineering targets. This labeling FE improvement method did not require any hardware or software changes, thus, involved no additional expense.…
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Alleviating the Magnetic Effects on Magnetometers using Vehicle Kinematics for Yaw Estimation for Autonomous Ground Vehicles

Michigan Technological University-Ahammad Basha Dudekula, Jeffrey D. Naber
  • Technical Paper
  • 2020-01-1025
To be published on 2020-04-14 by SAE International in United States
Autonomous vehicle operation is dependent upon accurate position estimation and thus a major concern of implementing the autonomous navigation is obtaining robust and accurate data from sensors. This is especially true, in case of Inertial Measurement Unit (IMU) sensor data. The IMU consists of a 3-axis gyro, 3-axis accelerometer, and 3-axis magnetometer. The IMU provides vehicle orientation in 3D space in terms of yaw, roll and pitch. Out of which, yaw is a major parameter to control the ground vehicle’s lateral position during navigation. The accelerometer is responsible for attitude (roll-pitch) estimates and magnetometer is responsible for yaw estimates. However, the magnetometer is prone to environmental magnetic disturbances which induce errors in the measurement. The present work focuses on alleviating magnetic disturbances for ground vehicles by fusing the vehicle kinematics information with IMU senor in an Extended Kalman filter (EKF) with the vehicle orientation represented using Quaternions. In addition, the error in rate measurements from gyro sensor gets accumulated as the time progress which results in drift in rate measurements and thus affecting the vehicle…
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Development and demonstration of a class 6 range-extended electric vehicle for commercial pickup and delivery operation

Cummins Inc.-John Kresse, Ke Li, Jesse Dalton
National Renewable Energy Laboratory-Matthew A. Jeffers, Eric Miller, Kenneth Kelly
  • Technical Paper
  • 2020-01-0848
To be published on 2020-04-14 by SAE International in United States
Range-extended hybrids are an attractive option for medium- and heavy-duty (M/HD) commercial vehicle fleets because they offer the efficiency of an electrified powertrain and accessories with the range of a conventional diesel powertrain. The vehicle essentially operates as if it was purely electric for most trips, while ensuring that all commercial routes can be completed in any weather conditions or geographic terrain. Fuel use and point-source emissions can be significantly reduced, and in some cases eliminated, as many shorter routes can be fully electrified with this architecture. Under a U.S. Department of Energy award for M/HD Vehicle Powertrain Electrification, Cummins has developed a plug-in hybrid electric (PHEV) class 6 truck with a range-extending engine designed for pickup and delivery application. The National Renewable Energy Laboratory (NREL) assisted by developing a representative work day drive cycle for class 6 operation and adapting it to enable track testing. A novel, automated driving system was developed and utilized by Southwest Research Institute (SwRI) to improve the repeatability of vehicle track testing used to quantify vehicle energy consumption. Cummins…
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Development of GM 10-Speed Allison Heavy Duty (HD) Transmission

General Motors LLC-Chi Teck Lee, David Ames, Brett Caldwell, Matthew Knoth, Timothy Reinhart, Jeffrey Kelly, Rajesh Kannan, German Tanasi
  • Technical Paper
  • 2020-01-0438
To be published on 2020-04-14 by SAE International in United States
This paper describes the development of GM 10-Speed Allison Heavy Duty (HD) Transmission. The trend of engine power and towing capacity in the automotive heavy-duty truck segment has been steadily climbing for a past 10 years. The development of GM 10-Speed Allison Heavy Duty Transmission is designed to be best in class for towing performance with no compromise in fuel economy. GM 10-Speed Allison Heavy Duty Transmission also gives the customers the option to order an integrated power transfer unit to improve the installation of power transfer or generation accessories. GM Allison HD truly brings the best of towing performance and fuel economy to the customers.
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NHTSA's 2018 Heavy Vehicle Automatic Emergency Braking Test Track Research Results

NHTSA-Devin Elsasser
Transportation Research Center Inc.-M. Kamel Salaani, Christopher Boday
  • Technical Paper
  • 2020-01-1001
To be published on 2020-04-14 by SAE International in United States
This paper presents National Highway Traffic Safety Administration’s 2017 and 2018 test track research results with heavy vehicles equipped with forward collision warning and automatic emergency braking systems. Newly developed objective test procedures were used to perform and collect performance data with three single-unit trucks equipped with the crash avoidance systems. The results of this research show that the test procedures are applicable to many heavy vehicles and indicate that performance improvements in heavy vehicles equipped with these safety systems can be objectively measured.
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A Pre-warning Method for Cornering Speed of Concrete Mixer Truck

Suizhou-WUT Industry Research Institute-Gangfeng Tan
Wuhan University of Technology-Yifeng Jiang, Haoyu Wang, Zelong Wang, Zhenyu Wang, Ming Li
  • Technical Paper
  • 2020-01-1003
To be published on 2020-04-14 by SAE International in United States
The high gravity center of the concrete mixer truck reduces the truck’s stability while steering, and the rolling stirring tank makes the stability even worse than the regular engineering vehicle due to the dynamic variation of centroid position. Most of the researches on the rollover stability of concrete mixer trucks focus on the rollover model establishment and dynamics simulation module. The influence of concrete centroid changes is ignored when the safe cornering speed is calculated. This paper proposes a pre-warning method for cornering speed of concrete mixer truck based on centroid dynamic simulation. In the method, the mixing tank stirring model and the vehicle driving dynamics model are established on the Fluent and TruckSim simulation platforms, respectively.The theoretical speed threshold obtained by simulation is used as the evaluation index of warning of the speed for steering. First, the dynamic simulation of the stirring tank model is carried out by Fluent. According to Newton Leibniz numerical calculation method, Matlab is used to obtain the mathematical model of the centroid position and the main parameters of the…
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Experimental-numerical correlation of a multi-body model for comfort analysis of an heavy truck

CNH Industrial-Andrea Morello, Vladi Nosenzo, Enrica Capitelli
Politecnico di Torino-Enrico Galvagno, Michele Galfrè, Mauro Velardocchia
  • Technical Paper
  • 2020-01-0768
To be published on 2020-04-14 by SAE International in United States
In automotive market, today more than in the past, it is very important to reduce time to market and, mostly, developing costs before the final production start. Ideally, bench and the on-road tests can be replaced by multi-body studies because virtual approach guarantees test conditions very close to reality and it is able to exactly replicate the standard procedures. Approval authorities are starting to look at simulations to release homologation certificates. Therefore, today, it is essential to create very reliable models, able to forecast the vehicle behavior on every road condition (including uneven surfaces). The aim of this study is to build a reliable multi-body model of a heavy commercial vehicle and to correlate experimental and numerical data related to comfort analysis for validation purposes. Experimental results are recorded during tests carried out at different speeds and loading conditions on a Belgian blocks track. Simulation data are obtained reproducing the on-road test conditions in multi-body environment. The virtual vehicle is characterized by rigid and flexible bodies, the tire model used is FTire (Flexible Structure Tire…
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Statistical Analysis of City Bus Driving Cycle Features for the Purpose of Multidimensional Driving Cycle Synthesis

University of Zagreb-Jakov Topić, Branimir Skugor, Josko Deur
  • Technical Paper
  • 2020-01-1288
To be published on 2020-04-14 by SAE International in United States
Driving cycles are typically defined as time profiles of vehicle velocity, and as such they reflect basic driving characteristics. They have a wide application from the perspective of both conventional and electric road vehicles, ranging from prediction of fuel/energy consumption (e.g. for certification purposes), estimation of greenhouse gas and pollutant emissions to selection of optimal vehicle powertrain configuration and design of its control strategy. In the case of electric vehicles, the driving cycles are also applied to determine effective vehicle range, battery life period, and charging management strategy. Nowadays, in most applications artificial certification driving cycles are used. As they do not represent realistic driving conditions, their application results in generally unreliable estimates and analyses. Therefore, recent research efforts have been directed towards development of statistically representative synthetic driving cycles derived from recorded GPS driving data. The state-of-the-art synthesis approach is based on Markov chains, typically including vehicle velocity and acceleration as Markov chain states. However, apart from the vehicle velocity and acceleration, a road slope and vehicle mass are also shown to significantly impact…
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Investigation of Transient Aerodynamic Effects on Public Highways in Comparison to Individual Driving Situations on a Test Site

FKFS-Felix Wittmeier, Andreas Wagner, Jochen Wiedemann
German Aerospace Center (DLR)-Henning Wilhelmi, Andreas Dillmann
  • Technical Paper
  • 2020-01-0670
To be published on 2020-04-14 by SAE International in United States
Natural wind, roadside obstacles, terrain roughness, and traffic can influence the incident flow of a vehicle driven on public roads. These on-road conditions differ from the idealized statistical steady-state flow environment utilized in CFD simulations and wind tunnel experiments. To understand these transient on-road conditions better, measurements were taken on a test site and on German Autobahn, resulting in the characterization of the transient aerodynamic effects around a vehicle. A compact car was equipped with a measurement system that is capable of determining the transient airflow around the vehicle and the vehicle’s actual driving state. This vehicle was driven several times on a fixed route to investigate different traffic densities on public highways in southern Germany. The tests were conducted under consistent weather conditions and average wind velocities of 2-5 m/s. During the tests the transient incident flow and pressure distribution on the vehicle surface were measured. With the same vehicle, individual driving situations were recreated on a test site. This paper presents a comparison of the aerodynamic characteristics measured by the vehicle during a…
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Vibration and Dynamic Analysis of Right-angle Geared Drives Considering the Influence of Gear-Shaft-Bearing Assembly Design

Marshall University-Xia Hua
  • Technical Paper
  • 2020-01-0415
To be published on 2020-04-14 by SAE International in United States
Dynamics of hypoid or spiral bevel gears like most high-speed precision gears employed in the powertrains of automobiles, commercial trucks, and off highway vehicles are significantly influenced by the design of the shafts and bearings. The finite element modeling approach is one of the useful methodologies applied to perform gear dynamic analysis. One of the major advantages of the finite element modeling approach is that it is able to account for the gear-shaft-bearing assembly design more accurately than other modeling approaches, for example, the lumped parameter modeling approach. In this paper, the finite element formulation, which can generally represent more complete characteristics of the gear-shaft-bearing assembly design, is employed to investigate how the key design changes of gear-shaft-bearing assembly influence the dynamics of spiral bevel gears. Accordingly, the underlying physics controlling these effects is also uncovered.