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Optimal Engine Re-Start Strategy on a Mild Hybrid Powertrain by Means of Up-Front Modelling

Ford Werke GmbH-Harald Stoffels, Shan-An Kao, Michael Frenken
  • Technical Paper
  • 2019-24-0206
To be published on 2019-08-15 by SAE International in United States
The ability to switch off the internal combustion engine (ICE) during vehicle operation is a key functionality in hybrid powertrains to achieve low fuel economy. However, this can affect driveability, namely acceleration response when an ICE re-engagement due to a driver initiated torque demand is required. The ICE re-start as well as the speed and load synchronisation with the driveline and corresponding vehicle speed can lead to high response times. To avoid this issue, the operational range where the ICE can be switched off is often compromised, in turn sacrificing fuel economy. Based on a 48V off-axis P2 hybrid powertrain comprising a lay-shaft transmission we present an up-front simulation methodology that considers the relevant parameters of the ICE like air-path, turbocharger, friction, as well as the relevant mechanical and electrical parameters on the hybrid drive side, including a simplified multi-body approach to reflect the relevant vehicle and powertrain dynamics. Applying different ICE re-start strategies at different speeds and gears, the driveability of the ICE re-engagement was evaluated using a commercialized driveability evaluation tool. The objective…
 

Quantification of Linear Approximation Error for Model Predictive Control of Spark Ignited Turbocharged Engines

Rohit Koli
Clemson Univ-Daniel Egan
  • Technical Paper
  • 2019-24-0014
To be published on 2019-08-15 by SAE International in United States
Modern turbocharged spark-ignition engines are being equipped with an increasing number of control actuators to simultaneously meet fuel economy, emissions and performance targets. The response time variations between a given set of engine control actuators tends to be significant during transients and necessitate highly complex actuator scheduling routines. Model Predictive Control (MPC) algorithms have the potential to significantly reduce calibration and control tuning efforts as compared to current methodologies that are designed around integration of multiple single-input single-output sub-system controllers. MPC systems simultaneously generate all actuator responses by using a combination of current engine conditions and optimization of a control-oriented plant model. To achieve real-time control the engine model and optimization processes must be computationally efficient without sacrificing effectiveness. Most MPC systems intended for real-time control utilize a linearized model that can be quickly evaluated using a sub-optimal optimization methodology. Online linearization of the engine model is computationally expensive so it should be performed as infrequently as possible. Since engine dynamics are non-linear, a local linearity approximation error occurs during this process. This research presents…
 
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Driving Simulator Performance in Charcot-Marie-Tooth Disease Type 1A

SAE International Journal of Transportation Safety

University of Iowa Carver College of Medicine, USA-Nivedita U. Jerath, Nazan Aksan, Jeffrey D. Dawson, Michael E. Shy
University of Nebraska Medical Center, USA-Matthew Rizzo
  • Journal Article
  • 09-07-01-0003
Published 2019-05-10 by SAE International in United States
Introduction: This study evaluates driving ability in those with Charcot-Marie-Tooth Disease Type 1A, a hereditary peripheral neuropathy. Methods: Individuals with Charcot-Marie-Tooth Disease Type 1A (n = 18, age = 42 ± 7) and controls (n = 19; age = 35 ± 10) were evaluated in a driving simulator. The Charcot-Marie-Tooth Neuropathy Score version 2 was obtained for individuals. Rank Sum test and Spearman rank correlations were used for statistical analysis. Results: A 74% higher rate of lane departures and an 89% higher rate of lane deviations were seen in those with Charcot-Marie-Tooth Disease Type 1A than for controls (p = 0.005 and p < 0.001, respectively). Lane control variability was 10% higher for the individual group and correlated with the neuropathy score (rS = 0.518, p = 0.040), specifically sensory loss (rS = 0.710, p = 0.002) and pinprick sensation loss in the leg (rS = 0.490, p = 0.054). Discussion: Driving simulator assessment demonstrated more lane control errors in those with Charcot-Marie-Tooth Disease Type 1A, which correlated with lower extremity sensory loss. There was…
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Prediction and Control of Response Time of the Semitrailer Air Braking System

SAE International Journal of Commercial Vehicles

Jiangsu University, China-Ren He, Chang Xu
  • Journal Article
  • 02-12-02-0011
Published 2019-05-09 by SAE International in United States
The response time of the air braking system is the main parameter affecting the longitudinal braking distance of vehicles. In this article, in order to predict and control the response time of the braking system of semitrailers, an AMESim model of the semitrailer braking system involving the relay emergency valve (REV) and chambers was established on the basis of analyzing systematically the working characteristics of the braking system in different braking stages: feedback braking, relay braking, and emergency braking. A semitrailer braking test bench including the brake test circuit and data acquisition system was built to verify the model with typical maneuver. For further evaluating the semitrailer braking response time, an experiment under different control pressures was carried out. Experimental results revealed the necessity of controlling the response time. As a result, a braking pressure compensation system was designed through adding intake and exhaust solenoid valves to the original braking system. A proportional-integral-derivative (PID) control strategy optimized by genetic algorithm (GA) was adopted to generate pulse width modulation (PWM) signals applied to the solenoid valves…
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Evaluation of Different ADAS Features in Vehicle Displays

University of Michigan-Abhishek Mosalikanti, Pranove Bandi, Sang-Hwan Kim
Published 2019-04-02 by SAE International in United States
The current study presents the results of an experiment on driver performance including reaction time, eye-attention movement, mental workload, and subjective preference when different features of Advanced Driver Assistance Systems (ADAS) warnings (Forward Collision Warning) are displayed, including different locations (HDD (Head-Down Display) vs HUD (Head-Up Display)), modality of warning (text vs. pictographic), and a new concept that provides a dynamic bird’s eye view for warnings.Sixteen drivers drove a high-fidelity driving simulator integrated with display prototypes of the features. Independent variables were displayed as modality, location, and dynamics of the warnings with driver performance as the dependent variable including driver reaction time to the warning, EORT (Eyes-Off-Road-Time) during braking after receiving the warning, workload and subject preference. The primary results were in line with previous research, validating previous claims of the superiority of HUD over HDD in warning delivery. It was also found that the text format of the warning yielded higher response rates along with lower workload, while most participants preferred the dynamic bird’s eye view layout.
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Automated Vehicle Disengagement Reaction Time Compared to Human Brake Reaction Time in Both Automobile and Motorcycle Operation

Dynamic Analysis Group LLC-Jeffrey T. Dinges, Nicholas J. Durisek
Published 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. The State of California autonomous vehicle testing regulations require every manufacturer authorized to test autonomous vehicles on public roads to submit an annual report summarizing disengagements. In early versions of the annual report, automated vehicle manufacturers were required to provide the time that it took for a human driver to take manual control of the vehicle when reporting vehicle disengagements. This study analyzes reported automated vehicle disengagement reaction times from 2015 through 2017 for various manufacturers that provided information to the California Department of Motor Vehicles while operating vehicles in autonomous mode. This study compares the reported automated vehicle operation disengagement reaction time to field literature in testing and experimentation on human brake reaction times for both automobile and motorcycle operation.
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Analysis of Driver’s Behavior under Following-Go Scenario

Tongji University, Shanghai, China-Lan Xia, Xichan Zhu, Zhixiong Ma
Published 2019-04-02 by SAE International in United States
The driver’s behavior under following-go scenario, which has been involved in little research so far, is an important part of the driver's following behavior. Analysis of driver's behaviour under following-go scenario is important for improving the performance and the adaptability of ACC (Adaptive Cruise Control) systems in urban traffic environment. In this paper driver’s behavior under following-go scenario in real traffic is studied based on naturalistic driving data. Starting reaction time and starting distance from the target vehicle are used to evaluate driver’s starting timing under following-go scenario. Starting acceleration is used to evaluate the effect of driver’s acceleration operation under following-go scenario. The naturalistic driving data collected in china is screened and classified and the following-go scenario is obtained. The driver’s behaviour parameters under following-go scenario are extracted and the statistical characteristics are obtained. Influence factors are analyzed with univariate ANOVA (Analysis of Variance) and regression analysis. The results show that the starting reaction time and the starting distance from the target vehicle approximately obey the lognormal probability distribution and the starting acceleration approximately…
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Optimization of Automotive Exhaust Sampling Parameters for Evaluation of After-Treatment Systems Using FTIR Exhaust Gas Analyzers

Horiba Ltd.-Jorge E. Lamas, Kenji Hara, Yuichi Mori
Published 2019-04-02 by SAE International in United States
Understanding the chemical reactions taking place in the engine and after-treatment systems is indispensable for minimizing harmful emissions in automotive exhaust gas. Real time gas analyzers for engine exhaust play a vital role for developing mathematical models and evaluating new after-treatment technologies. Gas analyzers using Fourier Transform Infrared Spectroscopy (FTIR) offer the advantage of continuous non-destructive simultaneous multicomponent analysis of a single gas stream. The ability of such analyzers to detect concentration fluctuations in the sample gas depends on a balance between its sample gas replacement rate and data sampling frequency. Increasing the sampling frequency is useful for detecting rapid concentration fluctuations, provided that the sample gas replacement rate is fast enough. This is commonly achieved by increasing the sample flow rate. However, such approach could be difficult during catalyst evaluation where the sample flow rate that may be extracted is limited. Recent developments in sample cell geometry and gas sampling method have improved gas replacement rate in HORIBA’s FTIR exhaust gas analyzers, without the need to increase sample flow rate. The response time and…
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Driver Behavior in Left Turn across Path from Opposite Direction Crash and near Crash Events from SHRP2 Naturalistic Driving

Crash Safety Research-Swaroop Dinakar, Jeffrey Muttart
Published 2019-04-02 by SAE International in United States
The turn-across-path from opposite-direction [LTAP-OD] crash type contributes to one of the major fatal crash types in young drivers. Drivers responses in police reportable and severe crashes and near crashes involving an LTAP-OD scenario were evaluated from query of the Second Strategic Highway Research Program [SHRP-2]. This research examined the responses of through drivers. 122 such events were analyzed to extract driver braking behavior, secondary tasks, age, and perception-response times. All measures of through driver variables were compared with respect to turning driver behavior. The study aimed to identify the trigger event for drivers to respond to the left turning vehicle. Time to contact was a significant factor which affected driver response times. Drivers responded significantly faster when subjected to shorter time to contact events compared to longer ones. Other short time to contact events included when the turning vehicle did not stop before entering the intersection, or when the turning vehicle was visible for a short duration. Driver factors such as age, gender or secondary task engagement did not significantly influence response times.
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Effect of Circumferential Magnetic Field on Braking Performance of a Direct Vane Magnetorheological Fluid Retarder

Wuhan University of Technology-Jianjie Kuang, Gangfeng Tan, Yishi Wang, Xingmang Zheng, Shiping Huang, ZhiQiang Liu, Xuexun Guo
  • Technical Paper
  • 2019-01-0342
Published 2019-04-02 by SAE International in United States
The hydraulic retarder used in commercial vehicles can provide hydraulic damping to generate braking torque, reducing the pressure of the braking system on the slope section and increasing the safety. In this paper, the magnetorheological fluid with fast magnetic field reflection characteristics is used to increase the response speed of the hydraulic retarder, which can effectively reduce the response time of the hydraulic retarder. In this paper, the influence of the change of circumferential magnetic field on the braking torque of the magnetorheological fluid retarder is studied. This paper analyzed the internal flow characteristics and braking mechanism of the hydraulic retarder based on the traditional hydraulic retarder, established the mathematical model of the magnetorheological hydraulic retarder which based on the straight blade structure ,and studied the variation of the braking torque of the magnetorheological fluid retarder when the rotational speed changed under the condition of no magnetic field .Then based on the Bingham model, the relationship between the braking torque of the magnetorheological fluid retarder with the intensity of the circumferential magnetic field is analyzed…
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