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SAE 2000 Automotive Dynamics & Stability Conference
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Effect of Heavy Vehicle Suspension Designs on Dynamic Road Loading – A Comparative Study

AmirKabir University of Technology-Mahyar Naraghi, Esmaeil Najaf zadeh
Published 2001-11-12 by SAE International in United States
In this paper road damage caused by heavy vehicles is studied. The effects of passive, semi-active and active suspension designs on dynamic road loading are compared. Attention is given to develop an accurate vehicle model with useful tandem suspension behavior. A nonlinear two-dimensional model of tractor-semitrailer is considered. The model includes nonlinear behavior of leaf spring and tandem suspension in the trailer axles. To obtain accurate results, a realistic road profile model is considered. The control scheme of the semi-active suspension system is based on the modified skyhook damper model. For the active suspension control system design, due to nonlinearity in the vehicle model, a linear quarter vehicle model is considered. Then linear quadratic optimal technique is employed to design the control law. Two road damage criteria were applied to assess the vehicle performance: The dynamic road stress factor and the 95th percentile dynamic loads. Simulation results of the vehicle model with the three suspension systems are presented. Based on the first criteria, road damage for semi-active and active suspensions compared with that of passive…
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Analysis of Vehicle Response Data Measured During Severe Maneuvers

S.E.A., Inc.-Gary J. Heydinger
TRC, Inc.-J. Gavin Howe
Published 2000-05-15 by SAE International in United States
During the past few years, the National Highway Traffic Safety Administration's (NHTSA) Vehicle Research and Test Center has generated a plethora of reliable vehicle test data during their efforts to study vehicle rollover propensity. This paper provides further analyses of a small selection of some of the data. The analyses provided here derive in part from the previous work, trying to answer some of the questions spawned by earlier analyses. The purpose of this paper is to introduce several new concepts to the study of vehicle roll stability and provide case studies using the results available from the NHTSA testing. Results from several severe maneuvers are studied in detail to gain understanding of vehicle response in these cases.
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Bosch ESP Systems: 5 Years of Experience

Robert Bosch G.m.b.H.-A. T. van Zanten
Published 2000-05-15 by SAE International in United States
Although the total number of car occupants involved in accidents in Germany has not significantly reduced during the past 10 years, the number of fatalities has steadily decreased. Most of the severe accidents result from a loss of control of the car. The problem of the driver losing control of his car will be explained. This problem is then used to formulate the goal for the vehicle dynamics control system ESP (Electronic Stability Program, also known as VDC). The approach chosen to reach this goal will then be shown. It will be shown that the vehicle slip angle is a crucial indicator for the maneuverability of the automobile. Since the complete vehicle state is not readily available, estimation algorithms are used to supply the control algorithms with sufficient information. With the automatic control of the slip angle the required yaw moment can be generated by individual wheel slip control. By using two examples it will be shown, that ESP can significantly improve vehicle handling in extreme maneuvers by automatically controlling the brakes and the engine.
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Design of Front Wheel Active Steering for Improved Vehicle Handling and Stability

North American Car Group, General Motors Corp.-Sanjay Singh
Published 2000-05-15 by SAE International in United States
Active steering has received lot of attention in the recent years because of the development of vehicle stability control systems and intelligent vehicle highway systems. Active steering systems allow for correction of the steer angle to achieve the desired vehicle yaw gain. The proposed system can be easily integrated with the vehicle stability control systems that use braking to control the vehicle yaw gain. The paper describes the concept of front wheel active steering system and the design techniques involved in order to achieve the desired performance from the system. The design techniques demonstrated in the paper do not address noise (gear rattles, motor noise, gear whine etc), electromagnetic compatibility and thermal issues related to DC motor and digital controller.
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A Model-Based Failsafe System for the Continental TEVES Electronic-Stability-Program (ESP)

Continental Teves AG & Co. oHG-H. Fennel
University of Applied Sciences Gelsenkirchen-E. L. Ding
Published 2000-05-15 by SAE International in United States
The Electronic Stability Program (ESP) is a vehicle dynamics control system that supports the driver in critical driving situations. A basic component integrated in the ESP-system is an on-line sensor monitoring system which is mainly used for detecting faults in sensors as early as possible so that an erroneous control or system malfunction can be prevented. Aim of this contribution is to present a model based sensor monitoring system for ESP that was developed, implemented, and is produced in large volumes by Continental Teves.
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Development of an Automotive Rollover Sensor

Delphi Automotive Systems-Ed Wallner, Jan Schiffmann
Published 2000-05-01 by SAE International in United States
It is estimated that in the United States, nearly one quarter of all fatal automobile accidents involve a vehicle rollover. [1] In order to reduce fatalities and serious injuries, it is desirable to develop a sensing system that can detect an imminent rollover condition with sufficient time to activate occupant safety protection devices. The goals of a Rollover Sensing Module (RSM) are; 1To accurately estimate vehicle roll and pitch angles2To reliably predict in a timely manner an imminent rollover3To eliminate false activation of safety devices4To function properly during airborne conditions5To be as autonomous as possible, not requiring information from other vehicle subsystems.
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Development of Active-Traction Control System

Aisin Seiki Co., Ltd.-Tosimi Ishikawa
Toyota Motor Corp.-Kazushi Hosomi, Akira Nagae, Shinsuke Yamamoto, Yosuke Takahira, Masamichi Koizumi
Published 2000-05-01 by SAE International in United States
Active-TRAC (A-TRAC) is the system for off-road 4WD vehicles. This system consists of independent four wheel brake control system and engine torque control system. This system applies the brake to any spinning wheel, and sends torque to the other wheels with grip. Therefore, the vehicle gets strong LSD(Limited Slip Differential) effect, and it has the same traction performance as a center and rear differential locked vehicle. Because the vehicle with A-TRAC does not have a differential locking mechanism, it no longer has the phenomenon of tight corner braking, and it frees a driver from operating the differential locking system. Therefore anyone can easily enjoy off-road driving with A-TRAC.
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MRA Vehicle Dynamics Simulation-Matlab®/Simulink®

Milliken Research Associates, Inc.-Edward M. Kasprzak, Douglas L. Milliken
Published 2000-05-01 by SAE International in United States
Milliken Research Associates has developed a new simulation tool, named Vehicle Dynamics Simulation-Matlab/Simulink (VD-M/S). Produced for the government's Variable Dynamic Testbed Vehicle (VDTV), VD-M/S is an 18 degree-of-freedom simulation programmed in the Matlab/Simulink environment. It contains a detailed non-linear tire model, kinematic and compliance effects, aerodynamic loadings, etc. as do MRA's other simulation programs. Unique to VD-M/S is its development from Day One as a simulation catered to the inclusion and exploration of active systems within the vehicle.
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Using μ Feedforward for Vehicle Stability Enhancement

University of California-Taehyun Shim, Donald Margolis
Published 2000-05-01 by SAE International in United States
Vehicle stability augmentation has been refined over many years, and currently there are commercial systems that control right/left braking and throttle to create vehicles that remain controlled when road conditions are very poor. These systems typically use yaw rate and lateral acceleration in their control philosophy. The tire/road friction coefficient, μ, has a significant role in vehicle longitudinal and lateral control, and there has been associated efforts to measure or estimate the road surface condition to provide additional information for the stability augmentation system.In this paper, a differential braking control strategy using yaw rate feedback, coupled with μ feedforward is introduced for a vehicle cornering on different μ roads. A nonlinear 4-wheel car model is developed. A desired yaw rate is calculated from the reference model based on the driver steering input. It is shown that knowledge of μ offers significant improvement of the vehicle desired trajectory over that of a yaw rate controller alone. Uncertainties and time delay in estimating μ are shown to still yield a system that is superior to using no…
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Dynamics Simulation Research on Rigid-Elastic Coupling System of Car Suspension

Jilin University of Technology-Yi Lin, Wenzhang Zhan, Yan Liu, Xin Zhong
Published 2000-05-01 by SAE International in United States
In modern car, to reduce car deadweight, lightweight technology is widely used; and to improve comfortable and handling performance, many rubber bushings installed between car body and suspension. These parts have difference characteristics during car running at high speed comparing these at static state.Accounting the suspension performance has a decisive influence on a car, the flexible parts should be taken into account in the suspension/steering system simulation model. As a deviant phenomenon, the steering wheel shimmy affects the suspension's dynamic characteristics greatly. To analysis this abnormal running state, the front wheel bounce tracks were figured out by using different front suspension model. The flexible parts installed in suspension are idealized respectively as rigid poles, flexible beams or forces, hence, the rigid suspension analytical model and the rigid-elastic suspension model analytical were built respectively.In this paper, suspension dynamic performance and flexible parts' influence were suggested to analyze, and the sensitivity analyses are suggested to reduce the steering wheel high frequency shimmy. The ADAMS” program is used to simulate the test condition in sensitivity analysis and to…
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