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Development of an Analytical Method for Rear Differential Gear Whine Noise Utilizing Principal Component Contribution by OTPA and CAE

Toyota Motor Corp.-Miho Nakatsuka, Tetsuya Miwa
Osaka Institute of Technology-Junji Yoshida
Published 2019-06-05 by SAE International in United States
The progress of vehicle electrification has reduced engine noise and the improvement of rear differential gear whine noise has become more important for customer satisfaction. Rear differential gear whine noise is a result of the vibration generated by the transmission error of the gears transmitted to the cabin from various paths. As several components have a contribution, identifying key paths to develop an effective countermeasure becomes time consuming.Operational transfer path analysis (OTPA) is one of the TPA methods to determine the main path and contributing part using only the operational data. However, in cases where many reference points are set on the same frame or body, the contribution becomes similar because of high correlation between the reference data set. As a result, finding the main transfer path becomes difficult. To overcome this issue, the principal component (PC) contribution obtained from the correlated reference signals was established by modifying the OTPA process. Through this process, important vibration behavior of the target structure can be obtained as the high contributing PC mode. In this paper, this approach…
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Effects of the Feature Extraction from Road Surface Image for Road Induced Noise Prediction Using Artificial Intelligence

Toyota Motor Corp.-Shunsuke Nakamura, Masashi Komada, Keisuke Ishizaki
Gifu University-Yuichi Matsumura, Kojiro Matsushita
Published 2019-06-05 by SAE International in United States
Next generation vehicles driven by motor such as electric vehicles and fuel cell vehicles have no engine noise. Therefore the balance of interior noise is different from the vehicles driven by conventional combustion engine. In particular, road induced noise tends to be conspicuous in the low to middle vehicle speed range, therefore, technological development to reduce it is important task. The purpose of this research is to predict the road induced noise from the signals of sensors adopted for automatic driving for utilizing the prediction result as a reference signal to reduce road induced noise by active noise control (ANC). Using the monocular camera which is one of the simplest image sensors, the road induced noise is predicted from the road surface image ahead of the vehicle by machine learning. The effects to extract features (Histograms of Oriented Gradients (HOG) feature, autoencoder feature, Convolutional Neural Network (CNN) feature) from road surface images are evaluated by visualization result of t-SNE. From the features acquired by the above method, the frequency characteristics of the road induced noise…
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Machine Learning Based Technology for Reducing Engine Starting Vibration of Hybrid Vehicles

Toyota Motor Corp.-Kento Shimode, Keisuke Ishizaki, Masashi Komada
Published 2019-06-05 by SAE International in United States
Engine starting vibration of hybrid vehicle with Toyota hybrid system has variations even in the same vehicle, and a large vibration that occurs rarely may cause stress to the passengers. The contribution analysis based on the vibration theory and statistical analysis has been done, but the primary factor of the rare large vibration has not been clarified because the number of factors is enormous. From this background, we apply machine learning that can reproduce multivariate and complicated relationships to analysis of variation factors of engine starting vibration. Variations in magnitude of the exciting force such as motor torque for starting the engine and in-cylinder pressure of the engine and timing of these forces are considered as factors of the variations. In addition, there are also nonlinear factors such as backlash of gears as a factor of variations. For the variation factor analysis, it is difficult to measure the physical quantities mentioned above from experiments, because of the high time load of installing measuring sensors and lack of measurement technology for some factors. On the other…
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Determine 24 GHz and 77 GHz Radar Characteristics of Surrogate Grass

Toyota Motor Corp.-Rini Sherony
Indiana University; Purdue University-Jun Lin, Stanley Chien, Qiang Yi, Yaobin Chen
Published 2019-04-02 by SAE International in United States
Road Departure Mitigation System (RDMS) is a new feature in vehicle active safety systems. It may not rely only on the lane marking for road edge detection, but other roadside objects This paper discusses the radar aspect of the RDMS testing on roads with grass road edges. Since the grass color may be different at different test sites and in different seasons, testing of RDMS with real grass road edge has the repeatability issue over time and locations. A solution is to develop surrogate grass that has the same characteristics of the representative real grass. Radar can be used in RDMS to identify road edges. The surrogate grass should be similar to representative real grass in color, LIDAR characteristics, and Radar characteristics. This paper provides the 24 GHz and 77 GHz radar characteristic specifications of surrogate grass.
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Application of Dynamic Mode Decomposition to Influence the Driving Stability of Road Vehicles

Toyota Motor Corp.-Yusuke Nakae, Hiroshi Tanaka
Altair Engineering-Daiki Matsumoto, Christoph Niedermeier
Published 2019-04-02 by SAE International in United States
The recent growth of available computational resources has enabled the automotive industry to utilize unsteady Computational Fluid Dynamics (CFD) for their product development on a regular basis. Over the past years, it has been confirmed that unsteady CFD can accurately simulate the transient flow field around complex geometries. Concerning the aerodynamic properties of road vehicles, the detailed analysis of the transient flow field can help to improve the driving stability. Until now, however, there haven’t been many investigations that successfully identified a specific transient phenomenon from a simulated flow field corresponding to driving stability. This is because the unsteady flow field around a vehicle consists of various time and length scales and is therefore too complex to be analyzed with the same strategies as for steady state results. Dynamic Mode Decomposition (DMD) extracts the coherent structures from complex, transient flow fields, which can help to identify certain target phenomena. However, one issue in the practical application of DMD is the difficulty to find a connection between a computed mode and an actual aerodynamic effect on…
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Effect of High RON Fuels on Engine Thermal Efficiency and Greenhouse Gas Emissions

Toyota Motor Corp.-Nozomi Yokoo, Koichi Nakata
ExxonMobil Fuels and Lubricants Co.-Abdelhadi Sahnoune
Published 2019-04-02 by SAE International in United States
Historically, greenhouse gas (GHG) emissions standards for vehicles have focused on tailpipe emissions. However, sound environmental policy requires a more holistic well-to-wheels (WTW) assessment that includes both production of the fuel and its use in the vehicle. The present research explores the net change in WTW GHG emissions associated with moving from regular octane (RO) to high octane (HO) gasoline. It considers both potential increases in refinery emissions from producing HO fuel and potential reductions in vehicle emissions through the use of fuel-efficient engines optimized for such fuel. Three refinery configurations of varying complexity and reforming capacity were studied. A set of simulations covering different levels of HO gasoline production were run for each refinery configuration. Two engine designs were considered: one which could take little advantage of higher octane fuel to increase efficiency, and one which could be adjusted further to take advantage of the higher octane. WTW GHG emissions were analyzed within a life cycle analysis framework, where the upstream emissions of raw material and utility inputs to the refinery were added to…
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Has Electronic Stability Control Reduced Rollover Crashes?

Toyota Motor Corp.-Rini Sherony
Virginia Tech-Luke Riexinger, Hampton Gabler
Published 2019-04-02 by SAE International in United States
Vehicle rollovers are one of the more severe crash modes in the US - accounting for 32% of all passenger vehicle occupant fatalities annually. One design enhancement to help prevent rollovers is Electronic Stability Control (ESC) which can reduce loss of control and thus has great promise to enhance vehicle safety. The objectives of this research were (1) to estimate the effectiveness of ESC in reducing the number of rollover crashes and (2) to identify cases in which ESC did not prevent the rollover to potentially advance additional ESC development.All passenger vehicles and light trucks and vans that experienced a rollover from 2006 to 2015 in the National Automotive Sampling System Crashworthiness Database System (NASS/CDS) were analyzed. Each rollover was assigned a crash scenario based on the crash type, pre-crash maneuver, and pre-crash events. The Insurance Institute for Highway Safety ESC availability database was matched to each NASS/CDS case vehicle by the vehicle make, model, and model year. ESC effectiveness was computed using the quasi-induced exposure method.From 2006-2015, control loss was a factor in 29.7%…
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Color and Height Characteristics of Surrogate Grass for the Evaluation of Vehicle Road Departure Mitigation Systems

Toyota Motor Corp.-Rini Sherony
Indiana University; Purdue University-Qiang Yi, Dan Shen, Jun Lin, Stanley Chien, Lingxi Li, Yaobin Chen
Published 2019-04-02 by SAE International in United States
In recent years Road Departure Mitigation Systems (RDMS) is introduced to the market for avoiding roadway departure collisions. To support the performance testing of the RDMS, the most commonly seen road edge, grass, is studied in this paper for the development of standard surrogate grass. This paper proposes a method for defining the resembling grass color and height features due to significant variations of grass appearances in different seasons, temperatures and environments. Randomly selected Google Street View images with grass road edges are gathered and analyzed. Image processing techniques are deployed to obtain the grass color distributions. The height of the grass is determined by referencing the gathered images with measured grass heights. The representative colors and heights of grass are derived as the specifications of surrogate grass for the standard evaluation of RDMS.
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Long-Term Evolution of Straight Crossing Path Crash Occurrence in the U.S. Fleet: The Potential of Intersection Active Safety Systems

Toyota Motor Corp.-Rini Sherony
Virginia Tech-Max Bareiss, H. Gabler
Published 2019-04-02 by SAE International in United States
Intersection collisions currently account for approximately one-fifth of all crashes and one-sixth of all fatal crashes in the United States. One promising method of mitigating these crashes and fatalities is to develop and install Intersection Advanced Driver Assistance Systems (I-ADAS) on vehicles. When an intersection crash is imminent, the I-ADAS system can either warn the driver or apply automated braking. The potential safety benefit of I-ADAS has been previously examined based on real-world cases drawn from the National Motor Vehicle Crash Causation Survey (NMVCCS). However, these studies made the idealized assumption of full installation in all vehicles of a future fleet. The objective of this work was to predict the reduction in Straight Crossing Path (SCP) crashes due to I-ADAS systems in the United States over time. The proportion of new vehicles with I-ADAS was modeled using Highway Loss Data Institute (HLDI) fleet penetration predictions. The number of potential SCP conflicts was modeled as increasing year over year due to a predicted increase in Vehicle Miles Traveled (VMT) each year. Finally, the combined effect of…
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Development of an Emergency Stop Assist System

Toyota Motor Corp.-Kazuhiro Morimoto, Masato Takagi, Takashi Oda
Tri-AD-Masaki Takano, Naoki Nishimura
Published 2019-04-02 by SAE International in United States
Social concern with traffic accidents caused by driver’s medical emergencies has been growing for the last several years. In Japan, the government issued technical guidelines in June 2016 to promote systems that deal with such accidents. Based on those guidelines, the Emergency Stop Assist system was manufactured in October 2017 to help reduce such accidents. This article first describes its purpose and core design, then presents an overview of the system, and finally discusses its effectiveness.
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