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SAE International Journal of Passenger Cars Mechanical Systems
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Design and Testing of ABS for Electric Vehicles with Individually Controlled On-Board Motor Drives

SAE International Journal of Passenger Cars - Mechanical Systems

Flanders' DRIVE-Johan Theunissen, Karel Janssen
Ilmenau University of Technology-Valentin Ivanov, Barys Shyrokau, Dzmitry Savitski
  • Journal Article
  • 2014-01-9128
Published 2014-08-01 by SAE International in United States
The paper introduces the results of the development of anti-lock brake system (ABS) for full electric vehicle with individually controlled near-wheel motors. The braking functions in the target vehicle are realized with electro-hydraulic decoupled friction brake system and electric motors operating in a braking mode.The proposed ABS controller is based on the direct slip and velocity control and includes several main blocks for computing of predictive (feedforward) and reactive (feedback) brake torque, wheel slip observer, slip target adaptation, and the algorithm of brake blending between friction brakes and electric motors.The functionality of developed ABS has been investigated on the HIL test rig for straight-line braking manoeuvres on different surfaces with variation of initial velocity. The obtained experimental results have been compared with the operation of baseline algorithm of a hydraulic ABS and have demonstrated a marked effect in braking performance.
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Differences between Air-Dam Spoiler Performances in Wind Tunnel and On-Road Tests

SAE International Journal of Passenger Cars - Mechanical Systems

Honda R&D Co., Ltd.-Kensuke Koremoto, Munetsugu Kaneko
Suzuki Motor Corp.-Daichi Katoh, Yoshimitsu Hashizume
  • Journal Article
  • 2014-01-0609
Published 2014-04-01 by SAE International in United States
An air-dam spoiler is commonly used to reduce aerodynamic drag in production vehicles. However, it inexplicably tends to show different performances between wind tunnel and coast-down tests. Neither the reason nor the mechanism has been clarified.We previously reported that an air-dam spoiler contributed to a change in the wake structure behind a vehicle. In this study, to clarify the mechanism, we investigated the coefficient of aerodynamic drag CD reduction effect, wake structure, and underflow under different boundary layer conditions by conducting wind tunnel tests with a rolling road system and constant speed on-road tests.We found that the air-dam spoiler changed the wake structure by deceleration of the underflow under stationary floor conditions. Accordingly, the base pressure was recovered by approximately 30% and, the CD value reduction effect was approximately 10%. The ratio of the base pressure recovery to the CD value reduction effect was approximately 90%, suggesting that the main mechanism is the base pressure recovery produced by changing the wake structure. In contrast, the air-dam spoiler did not change the wake structure in on-…
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Influence of Active Suspension Preview Control on Vehicle Ride and Braking Performance

SAE International Journal of Passenger Cars - Mechanical Systems

IAE, TU Braunschweig-Mina M.S. Kaldas
South Valley University-Aref M.A. Soliman
  • Journal Article
  • 2014-01-0862
Published 2014-04-01 by SAE International in United States
The integrated control between the vehicle chassis subsystems (suspension, brake, and steering) became one of the most important aspects for current developments to improve the dynamics of the vehicles. Therefore, the aim of this study is to investigate the influence of the preview control of the active suspension on the vehicle ride and braking performance. The vehicle performance was examined theoretically using a longitudinal half vehicle model with four degrees of freedom considering the rotational motion of the tires. The active suspension system model, tire-road interface model and braking system model are included in the vehicle model.In order to study the influence of the preview control on the vehicle ride and braking performance, an active suspension system control algorithm employing the lock-ahead preview information and the wheel-base time delay based on the optimal control theory is derived. On the other hand, the ABS control algorithm is designed based on the slip-control strategy. The vehicle ride performance is evaluated in terms of discomfort and road holding, while the braking distance and time is considered as evaluation…
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Numerical Simulations of Flow around a Realistic Generic Car Model

SAE International Journal of Passenger Cars - Mechanical Systems

Ecole Centrale de Nantes-Emmanuel Guilmineau
  • Journal Article
  • 2014-01-0607
Published 2014-04-01 by SAE International in United States
This paper focuses on the numerical simulations of flow around a realistic generic car model called the DrivAer body. This new open-source model is based on the geometries of two medium sized cars, the Audi A4 and the BMW 3 series, and possesses more representative car features as the well-known generic Ahmed body. In this paper, only the fastback geometry is investigated. The flow solver used is ISIS-CFD developed by CNRS and Ecole Centrale de Nantes. This solver is based on a finite-volume method, and two turbulence modelizations are used: the Explicit Algebraic Reynolds Stress Model (EARSM) and a Detached Eddy Simulation (DES). Two meshes are used. For one, the walls are described with a wall function and the mesh contains 19 million cells. This mesh is called “Mesh 1”. For the second mesh, a low-Reynolds number turbulence model for the walls is used. In this case, the mesh contains 39 million cells, and is called “Mesh 2”. For the simulation with the EARSM model, the drag coefficient is well predicted while the lift coefficient…
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Electromagnetics, Structural Harmonics and Acoustics Coupled Simulation on the Stator of an Electric Motor

SAE International Journal of Passenger Cars - Mechanical Systems

ANSYS Inc.-Mohamed Senousy, Paul Larsen, Peiran Ding
  • Journal Article
  • 2014-01-0933
Published 2014-04-01 by SAE International in United States
Electric motors and generators produce vibrations and noise associated with many physical mechanisms. In this study, we look at the vibrations and noise produced by the transient electromagnetic forces on the stator of a permanent magnet motor. In the first stage, electromagnetic simulation is carried out to calculate the forces per tooth segment of the stator. The harmonic orders of the electromagnetic forces are then calculated using Fourier analysis, and forces are mapped to the mechanical harmonic analysis of the second stage. As a third stage, the vibrations of the structure are used to drive the boundary of acoustic domain to predict the noise. Finally, optimization studies are made over the complete system to improve the motor design and reduce noise. A simulation environment (ANSYS Workbench) is used to integrate a seamless workflow.
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Experimental Comparison of the Aerodynamic Behavior of Fastback and Notchback DrivAer Models

SAE International Journal of Passenger Cars - Mechanical Systems

Technische Universität Berlin-Dirk Wieser, Hanns-Joachim Schmidt, Stefan Müller, Christoph Strangfeld, Christian Nayeri, Christian Paschereit
  • Journal Article
  • 2014-01-0613
Published 2014-04-01 by SAE International in United States
The experimental investigation was conducted with a 25%-scaled realistic car model called “DrivAer” mounted in a wind tunnel. This model includes geometric elements of a BMW 3 series and an Audi A4, accommodating modular, rear-end geometries so that it represents a generalized modern production car. The measurements were done with two different DrivAer rear end configurations (fastback and notchback) at varying side-wind conditions and a Reynolds number of up to Re=3.2·106. An array of more than 300 pressure ports distributed over the entire rear section measured the temporal pressure distribution. Additionally, extensive flow visualizations were conducted.The combination of flow visualization, and spatially and temporally resolved surface pressure measurements enables a deep insight into the flow field characteristics and underlying mechanisms. Moreover, static pressure fluctuations indicate regions with a high turbulence level due to flow separation and interaction between different vortical structures. A directional decomposition of the pressure coefficient is demonstrated and acts generally normal to the surface of the vehicle, in the drag and lift direction.
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Under-Hood Air Flow Evaluation of Pedestrian-Friendly Front-End Style Using CFD Simulation

SAE International Journal of Passenger Cars - Mechanical Systems

CAE Engineer, R&D Center of SAIPA-Kambiz Jahani, Sajjad Beigmoradi
  • Journal Article
  • 2014-01-0762
Published 2014-04-01 by SAE International in United States
The efficiency of the vehicle cooling system strongly depends on the air flow through the radiator core. The flow through the radiator core in turn depends on other panels that are in the vicinity of the radiator. In this study, the effect of geometrical change at vehicle front-end including the whole bonnet, grille and bumper area is investigated by means of Computational Fluid Dynamics (CFD). Numerical modeling is carried out by means of CAE tools. Simulations are performed for maximum power and maximum torque conditions, monitoring the mass flow rate through the radiator core and velocity contribution over the radiator face. To the velocity field of the airflow, the heat exchangers are represented as porous media and fan module is modeled utilizing Multiple Reference Frame (MRF) approach. The validity of the developed simulation capability is tested by successful comparison with the available experimental data for the base model at the given operating conditions. On studying the model with complete new front-end style, local modifications are applied incorporating adding airguide, flap and anti-recycler in order to…
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Preview Enhanced Rule-Optimized Fuzzy Logic Damper Controller

SAE International Journal of Passenger Cars - Mechanical Systems

IAE, TU Braunschweig-Mina Kaldas, Kemal Caliskan, Roman Henze, Ferit Küçükay
  • Journal Article
  • 2014-01-0868
Published 2014-04-01 by SAE International in United States
New developments in road profile measurement systems and in semi-active damper technology promote the application of preview control strategies to vehicle suspension systems. This paper details a new semi-active suspension control approach in which a rule-optimized Fuzzy Logic controller is enhanced through preview capability. The proposed approach utilizes an optimization process for obtaining the optimum membership functions and the optimum rule-base of the preview enhanced Fuzzy Logic controller. The preview enhanced Fuzzy Logic controller uses the feedforward road input information and the feedback vehicle state information as the controller inputs. An eleven degree of freedom full vehicle model, which is validated through laboratory tests performed on a hydraulic four-poster shaker, is used for the controller synthesis. The cost function including both ride comfort and road holding performance of the full vehicle is minimized through a discrete optimization process utilizing Genetic Algorithm (GA). The preview distance is also considered as a design parameter during the optimization process. The performance of the preview enhanced rule-optimized Fuzzy Logic controller is evaluated by using a measured stochastic road profile…
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Location-Aware Adaptive Vehicle Dynamics System: Brake Modulation

SAE International Journal of Passenger Cars - Mechanical Systems

Virginia Tech-Sukhwan Cho, Rebecca Anne Bandy, John Ferris
Volkswagen Group of America, Inc.-Joerg Schlinkheider, Marc Wimmershoff
  • Journal Article
  • 2014-01-0079
Published 2014-04-01 by SAE International in United States
A Location-Aware Adaptive Vehicle Dynamics System (LAAVDS) is developed to assist the driver in maintaining vehicle handling capabilities through various driving maneuvers. An integral part of this System is an Intervention Strategy that uses a novel measure of handling capability, the Performance Margin, to assess the need to intervene. Through this strategy, the driver's commands are modulated to affect desired changes to the Performance Margin in a manner that is minimally intrusive to the driver's control authority. Real-time implementation requires the development of computationally efficient predictive vehicle models. This work develops one means to alter the future vehicle states: modulating the driver's brake commands. This control strategy must be considered in relationship to changes in the throttle commands. Three key elements of this strategy are developed in this work. An algorithm is developed to determine when to switch from a throttle-only control strategy to a braking strategy. A linearized brake model is developed to estimate the required brake modulation to affect the desired changes in longitudinal force. These predicted changes to the brake commands are…
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A Copula-Based Approach for Model Bias Characterization

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Motor Co.-Yan Fu, Ren-Jye Yang
University of Michigan-Zhimin Xi, Pan Hao
  • Journal Article
  • 2014-01-0735
Published 2014-04-01 by SAE International in United States
Available methodologies for model bias identification are mainly regression-based approaches, such as Gaussian process, Bayesian inference-based models and so on. Accuracy and efficiency of these methodologies may degrade for characterizing the model bias when more system inputs are considered in the prediction model due to the curse of dimensionality for regression-based approaches. This paper proposes a copula-based approach for model bias identification without suffering the curse of dimensionality. The main idea is to build general statistical relationships between the model bias and the model prediction including all system inputs using copulas so that possible model bias distributions can be effectively identified at any new design configurations of the system. Two engineering case studies whose dimensionalities range from medium to high will be employed to demonstrate the effectiveness of the copula-based approach.
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