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Improvement of Tightening Reliability of Bolted Joints Using Elliptical Confidence Limit in Calibrated Wrench Method

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe, Satoshi Kobayashi
  • Technical Paper
  • 2020-01-0218
To be published on 2020-04-14 by SAE International in United States
The calibrated wrench method is used in the tightening of bolts in manufacturing industries in the case of a large amount of tightening work. It is important to apply a large initial clamping force to ensure tightening reliability and prevent self-loosening, fatigue breakage, and so forth. In this method, the clamping force of bolted joints is controlled using a torque wrench. However, since the clamping force is indirectly applied by a wrench, it varies greatly in the case of a large amount of tightening in a factory. Therefore, the calibrated wrench method is not so accurate from the viewpoint of clamping force control. It is conventionally thought that the distribution of the clamping force has the shape of a rhombus. When tightening torque and clamping force are considered to be two independent random variables, the clamping force is distributed within an elliptical confidence limit. Here, we show that the distribution of equivalent stress also has an elliptical confidence limit. Considering the permitted limit for working load stress on a bolted joint, the elliptical distribution has…
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A Development of the purge controller design based on H2 concentration estimator in Fuel Cell Electric Vehicle

Hyundai Motor Group-Soonwoo Kwon, Joonyong Lee, Soonill Jeon
  • Technical Paper
  • 2020-01-0854
To be published on 2020-04-14 by SAE International in United States
The optimal control of anode H2 concentration in fuel cell is the key performance parameter for efficiency and durability of the FCEV. Due to the immaturity of the H2 concentration sensor, the anode H2 concentration estimator has been developed based on the knowledge of physical laws. Modeling simplification of plumbing and duct in H2 supply system causes estimation error depending on the driving cycle and environment condition, but proper design of calibration parameters can make the error within reasonable range. In this paper, mathematical model of H2 concentration estimator is proposed and the effectiveness of purge controller based on the estimator is demonstrated.
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Model-Based Calibration of an Automotive Climate Control System

BMW AG-Gerrit Lassahn, Kang Qiu
TU Munich-Patrick Jahn
  • Technical Paper
  • 2020-01-1253
To be published on 2020-04-14 by SAE International in United States
In modern cars the control of heating, ventilation and air-conditioning (HVAC) systems is oftentimes realized by means of a cascade of gain scheduling controllers. The calibration of this control cascade is a complicated and strenuous, hence expensive process. To establish a model based calibration process, a fast executing and accurate model of the HVAC system is required. This paper describes a novel approach for the modelling of an automotive HVAC system. The model consists of a black box model trained with experimental data from a self-developed measurement setup. It is capable to predict the temperature and mass flow of the air entering the vehicle cabin at the different outlets. The measurement setup is based on a combination of temperature and velocity sensors. A measurement fault analysis is conducted to validate the accuracy of the measurement system. As the data collection is done under fluctuating ambient conditions, an extensive analysis of the impact of different ambient conditions on the HVAC unit is performed and incorporated into correction models that account for the different ambient conditions. Different…
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An Experimental Methodology for Measuring Resistance Forces of Light-Duty Vehicles under Real-World Conditions and the Impact on Fuel Consumption

Aristotle University of Thessaloniki-Dimitrios Komnos, Leonidas Ntziachristos
European Commission Joint Research-Georgios Fontaras, Jelica Pavlovic, Biagio Ciuffo
  • Technical Paper
  • 2020-01-0383
To be published on 2020-04-14 by SAE International in United States
A vital element of any vehicle-certification test is the use of representative values for the vehicle resistance forces. In most certification procedures, including the WLTP recently adopted by the EU, the latter is achieved mainly through coast down tests. Subsequently, the resistance values measured are used for setting up the chassis-dyno resistances applied during the laboratory measurements. These reference values are obtained under controlled conditions, while a series of corrections are applied to make the test procedure more repeatable and reproducible. In real driving, the actual vehicle road loads are influenced by a series of factors leading to a divergence between the certified fuel consumption values, and the real-world ones. An approach of calculating representative road loads during on-road tests can help to obtain a more unobstructed view of vehicle efficiency and, when needed, confirm the officially declared road loads. This approach is also essential for validating simulations and achieving better estimates of the actual fuel consumption, a requirement introduced by the new policy adopted in the EU. In this study, a series of on-road…
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Joint Calibration of Dual LiDARs and Camera Using a Circular Chessboard

Tongji University-Zhenwen Deng, Lu Xiong, Dong Yin, Fengwu Shan
  • Technical Paper
  • 2020-01-0098
To be published on 2020-04-14 by SAE International in United States
Environmental perception is a crucial subsystem in autonomous vehicles. In order to build safe and efficient traffic transportation, several researches have been proposed to build accurate, robust and real-time perception systems. Camera and LiDAR are widely equipped on autonomous self-driving cars and developed with many algorithms in recent years. The fusion system of camera and LiDAR provides state-of the-art methods for environmental perception due to the defects of single vehicular sensor. Extrinsic parameter calibration is able to align the coordinate systems of sensors and has been drawing enormous attention. However, differ from spatial alignment of two sensors’ data, joint calibration of multi-sensors (more than two sensors) should balance the degree of alignment between each two sensors. In this paper, we assemble a test platform which is made up of dual LiDARs and one monocular camera and use the same sensing hardware architecture as intelligent sweeper designed by our laboratory. Meanwhile, we propose the related joint calibration method using a circular chessboard. The center of circular chessboard is respectively detected in camera image to get pixel…
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Model-Based Design of a Hybrid Powertrain Architecture with Connected and Automated Technologies for Fuel Economy Improvements

Center For Automotive Research-Kristina Kuwabara, Jacqueline Karl-DeFrain
Center for Automotive Research-Mahaveer Kantilal Satra
  • Technical Paper
  • 2020-01-1438
To be published on 2020-04-14 by SAE International in United States
Simulation-based design of connected and automated hybrid-electric vehicles is a challenging problem. The design space is large, the systems are complex, and the influence of connected and autonomous technology on the process is a new area of research. The Ohio State University EcoCAR Mobility Challenge team developed a comprehensive design and simulation approach as a solution. This paper covers the detailed simulation work conducted after initial design space reduction was performed to arrive at a P0-P4 hybrid vehicle with a gasoline engine. Two simulation environments were deployed in this strategy, each with unique advantages. The first was Autonomie, which is a commercial software tool that is well-validated through peer-reviewed studies. This allowed the team to evaluate a wide range of components in a robust simulation framework. To ensure consistent evaluation between potential architectures, the team paired Autonomie with a particle swarm optimizer to automatically calibrate the hybrid supervisory control and achieve near optimal control calibrations. The team also utilized a dynamic programming model environment to evaluate the fuel economy impact of connected and autonomous systems…
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Quantifying Retroreflective Materials using Digital Imagery

JS Forensic Consulting, LLC-Jeffrey Suway
Momenta, LLC-Anthony Cornetto
  • Technical Paper
  • 2020-01-0570
To be published on 2020-04-14 by SAE International in United States
Retroreflection occurs when a light ray incident on a surface is reflected back towards the light source. The performance of a retroreflective material is of interest to accident reconstructionist, human factors professionals, lighting professionals, and roadway design professionals. The retroreflective effect of a material can be defined by the coefficient of retroreflection, which is a function of the light’s entrance angle and the viewer’s observation angle. The coefficient of retroreflection of a material is typically measured in a laboratory environment or in the field with a retroreflectometer. Often the material in question cannot be taken to a laboratory for testing and commercially available portable retroreflectometers are limited to entrance angles of 45 degrees or less and may be cost prohibitive in some cases. This paper presents a methodology to capture images of a retroreflective material at entrance angles between -90 degrees and 90 degrees and observations angles between 0.2 degrees and 1.2 degrees. The process of calibrating the camera and the light source is presented and the coefficient of retroreflection is calculated from the images…
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Pressure Tracking Control of Electro-Mechanical Brake Booster System

Jilin University-Weihong Yang, Jian Wu, Rui He, Bing Zhu, Jian Zhao, Zhicheng Chen
  • Technical Paper
  • 2020-01-0211
To be published on 2020-04-14 by SAE International in United States
The Electro-Mechanical Brake Booster system (EMBB) is a kind of novel braking booster system, which integrates active braking, regenerative braking, and other functions. It usually composes of a servo motor and the transmission mechanism. EMBB can greatly meet the development needs of vehicle intelligentization and electrification. During active braking, EMBB is required to respond quickly to the braking request and track the target pressure accurately. However, due to the highly nonlinearity of the hydraulic system and EMBB, traditional control algorithms especially for PID algorithm do not work well for pressure control. And a large amount of calibration work is required when applying PID algorithms to pressure control in engineering. In this paper, a fuzzy adaptive PI pressure control algorithm based on feed-forward is proposed to a novel self-designed EMBB mechanism, which is utilized to overcome the nonlinear pressure control problem when EMBB is in active braking and improve the control effect of PID algorithm. First, the structure of the EMBB system used in the paper and its working principle is presented. Second, this paper designs…
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High resolution global NOx sub-model for embedded system application with low calibration effort

Exothermia GmbH-Konstantinos Michos
Technische Hochschule Nuernberg-Georgios Bikas, Peter Weigand, Marina Brilz
  • Technical Paper
  • 2020-01-0246
To be published on 2020-04-14 by SAE International in United States
The starting point is a global model of NOx formation for stoichiometric and lean combustion of hydrocarbons developed on the basis of a single non-linear algebraic equation. The latter is the analytical solution of a system of differential equations describing the main kinetic reaction schemes of NOx formation. These take into account the thermal (Zeldovich) and the N2O reaction paths. The model has been validated in another study and proved to be suitable, on the one hand to be embedded in 1D and 3D simulation platforms, on the other hand for direct data evaluation and post-processing of engine testbench data. The non-linear algebraic equation for the calculation of the NOx concentration requires a numerical iterative solution method. This makes the model less attractive for a real-time application based on crank angle resolved information. However, its implementation on embedded systems for "in-situ" and "in memory" analysis of engine process data, or even its application as a virtual sensor, is of great importance due to its global nature and low calibration effort. Beside robustness, fast running times…
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Virtual Development of Injector Spray Targeting by Coupling 3D-CFD Simulations with Optical Investigations

FKFS-Marco Chiodi
University of Stuttgart-Antonino Vacca, Simon Hummel, Karsten Müller, Marc Reichenbacher, Michael Bargende
  • Technical Paper
  • 2020-01-1157
To be published on 2020-04-14 by SAE International in United States
Further improvements of internal combustion engines to reduce fuel consumption and to face future legislation constraints are strictly related to the study of mixture formation. The reason for that is the desire to supply the engine with homogeneous charge, towards the direction of a global stoichiometric blend in the combustion chamber. Fuel evaporation and thus mixture quality mostly depend on injector atomization features and charge motion within the cylinder. 3D-CFD simulations offer great potential to study not only injector atomization quality but also the evaporation behavior. Nevertheless coupling optical measurements and simulations for injector analysis is an open discussion because of the large number of influencing parameters and interactions affecting the fuel injection’s reproducibility. For this purpose, detailed numerical investigations are used to describe the injection phenomena. These intensive calculations are not advisable considering CFD virtual engine development. It is rather reasonable to find a methodology for a numerical characterization of the fuel injection process that takes into account both macroscopic and microscopic spray properties and to integrate these models into the complete engine simulations.…