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Technical Paper

A New Sliding Mode Controller for Four-Wheel Anti-Lock Braking System (ABS)

2000-05-01
2000-01-1639
This paper presents a new method for finding slip control law of Anti-lock Braking System (ABS), based on sliding mode control method . A four wheel car model with seven degrees of freedom is considered. Slip of each wheel is controlled separately so that it remains in the desired range for every kind of road condition, and by tuning desired slip undesired yaw on miu-split surfaces is prevented.
Technical Paper

Variable Effort Steering for Vehicle Stability Enhancement Using an Electric Power Steering System

2000-03-06
2000-01-0817
This paper investigates a method for improving vehicle stability by incorporating feedback from a yaw rate sensor into an electric power steering system. Presently, vehicle stability enhancement techniques are an extension of antilock braking systems in aiding the driver during vehicle maneuvers. One of the contributors to loss of vehicle control is the reduction in tactile feedback from the steering handwheel when driving on wet or icy pavement. This paper presents research indicating that the use yaw rate feedback improves vehicle stability by increasing the amount of tactile feedback when driving under adverse road conditions.
Technical Paper

Electronic Braking System of EV And HEV---Integration of Regenerative Braking, Automatic Braking Force Control and ABS

2001-08-20
2001-01-2478
The desirable braking system of a land vehicle is that it can stop the vehicle or reduce the vehicle speed as quickly as possible, maintain the vehicle direction stable and recover kinetic energy of the vehicle as much as possible. In this paper, an electronically controlled braking system for EV and HEV has been proposed, which integrates regenerative braking, automatic control of the braking forces of front and rear wheels and wheels antilock function together. When failure occurs in the electric system, the braking system can function as a conventional man-actuated braking system. Control strategies for controlling the braking forces on front and rear wheels, regenerative braking and mechanical braking forces have been developed. The braking energy that can be potentially recovered in typical driving cycle has been calculated. The antilock performance of the braking system has been simulated.
Technical Paper

Development of HILS System for ABS ECU of Commercial Vehicles

2001-10-01
2001-01-3186
Antilock Brake System (ABS) is designed to prevent wheels from locking. Therefore ABS, regardless of road conditions, improves directional stability, shortens stopping distance, and enhances maneuvering during braking. Hardware In-the-Loop Simulation (HILS) is and effective tool for design, performance evaluation and test of vehicle subsystems such as ABS, active suspension, and steering systems. A fourteen degrees-of-freedom vehicle dynamics model is simulated in alpha-chip processor board. The proposed HILS system is tested by a basic ABS control algorithm. This paper describes a HILS model for an ABS/ASR application. Also the design and implementation of HILS system for development of the ABS ECU (Electronic Control Unit) for commercial vehicles are presented. The HILS system simulation results show that the proposed HILS system may be used to realistically test performance, stability, and reliability of vehicle.
Technical Paper

Semi-lock brake system utilizing load sensing proportioning valve and spring membrane

2000-06-12
2000-05-0233
Anti-lock braking system is a modern braking system which could significantly improve directional stability and reduce stopping distance of a car. However this system still is too complicated and expensive to use on every car because its use complicated and control system. In this research, without using an expensive control system a combination of load-sensing proportioning valve and spring membrane was used as a main component to develop the effect of anti-lock braking system. Based on vertical load applied on each tire, a load-sensing proportioning valve could control fluid pressure to the appropriate level to lock the wheel. On the other hand, a spring membrane could fluctuate pressure of brake fluid in order to develop the effect of anti-lock braking system. The result shows that load-sensing proportioning valve alone could control fluid pressure in order to reach equal time lock between front and rear wheels.
Technical Paper

A study of road identification for anti-lock brake systems equipped only with wheel speed sensors

2000-06-12
2000-05-0236
Anti-lock brake systems (ABS) are now widely accepted and used on more and more motor vehicles. With the consideration of low product cost and technologies currently available, standard ABS has only wheel speed sensors to detect wheel angular velocities, not enough to directly obtain wheel slip ratios needed by control unit, but to calculate reference slip ratios with measured wheel angular velocities and estimated vehicle speed. Therefore, the road friction coefficient, which dominates vehicle deceleration during severe braking, is an important parameter in estimating vehicle speed. This paper analyzed wheel acceleration responses in simulations of severe braking on different road surfaces, and selected a pair of specific points to mark the wheel acceleration curve under each certain operating condition, such as road surface, pedal-braking torque and wheel vertical load.
Technical Paper

MOTORCYCLE BRAKING AND ITS INFLUENCE ON SEVERITY OF INJURY

2001-06-04
2001-06-0168
At first glance there seems to be no correlation between braking and injuries, but an in-depth study of fatal motorcycle collisions reveals the cause of accident to be incorrect braking. Modern motorcycles have excellent brakes but the driver is often overtaxed in pre-accident situations. There is a great risk that even an experienced driver will overbrake the front wheel due to the stress situation. As an investigation of 613 motorcycle collisions with cars shows, the only solution to this problem is to equip motorcycles with antilock braking systems. The reconstruction and practical analysis of these cases and a collaboration with the University of Darmstadt showed the different braking parameters, reduced braking distance and increased stability. The study also demonstrates the influence of different motorcycle and driver movement during the impact with or without a fall after emergency braking. This has a direct effect on the type of injuries suffered.
Technical Paper

Advanced Motorcycle Brake Systems - Recent Results

1983-02-01
830153
Results of an evaluation of possible advanced brake components and systems for motorcycles are reviewed. Potential improved conventional brake components included: friction materials aimed at improving wet brake performance; and components affecting brake system feel properties. A prototype all-mechanical antilock brake system was evaluated. Results showed improvements in performance may be realized via all three of these areas, based on prototype results that might apply to future designs.
Technical Paper

Performance of Antilock Brakes with Simplified Control Technique

1983-02-01
830484
The four-wheel controlling antilock brake system is considered as an effective safety device because of its capability to help a driver to maintain vehicle stability and steerability during panic braking even on a slippery road surface. This report deal with a simplified control technique which simultaneously controls right and left wheels on each front or rear axle. Both front wheels are controlled in response to a signal from the front wheel with the least slip, while both rear wheels are controlled in response to a signal from the rear wheel that has the greatest slip. A series of tests proved that this technique ensures vehicle steering ability even during panic braking. On a gravel and other rough roads, this system provided shorter stopping distance compared to other four-wheel antilock systems. It has been generally assumed that stopping distance extension on such roads is only one disadvantage of the four-wheel antilock brake system.
Technical Paper

An Analytical Approach to Antilock Brake System Design

1984-02-01
840249
An analytical method applicable to design and development of antilock brake systems is described. Dynamic components of antilock systems --- including vehicle, sensor, and modulator--are examined using nonlinear feedback control techniques. An overall design approach is illustrated via an example involving a motorcycle front brake and typical pneumatic modulator. A computer simulation is used to generate time and frequency responses of system components. These data are used to identify the preferred feedback structure. Results show that a stable antilock limit cycle can exist for wheel angular acceleration feedback, among other possibilities. Overall the method and results can provide additional insight into detailed requirements for antilock components and systems, and may hold potential for reducing development time and costs.
Technical Paper

Results from NHTSA's Experimental Examination of Selected Maneuvers that may Induce On-Road Untripped, Light Vehicle Rollover

2001-03-05
2001-01-0131
This paper summarizes the results of test maneuvers devised to measure on-road, untripped, rollover propensity. Complete findings from this research are contained in [1]. Twelve test vehicles, representing a wide range of vehicle types and classes were used. Three vehicles from each of four categories: passenger cars, light trucks, vans, and sport utility vehicles, were tested. The vehicles were tested with vehicle characterization and untripped rollover propensity maneuvers. The vehicle characterization maneuvers were designed to determine fundamental vehicle handling properties while the untripped rollover propensity maneuvers were designed to produce two-wheel lift for vehicles with relatively higher rollover propensity potential. The vehicle characterization maneuvers were Pulse Steer, Sinusoidal Sweep, Slowly Increasing Steer, and Slowly Increasing Speed. The rollover propensity maneuvers were J-Turn, J-Turn with Pulse Braking, Fishhook #1 and #2, and Resonant Steer.
Technical Paper

An Overview of the National Highway Traffic Safety Administration’s Light Vehicle Antilock Brake Systems Research Program

1999-03-01
1999-01-1286
This paper presents an overview of currently ongoing research by the National Highway Traffic Safety Administration (NHTSA) in the area of light vehicle (passenger cars and light trucks) Antilock Brake Systems (ABS). This paper serves as a lead-in to other papers that will be presented during this session. Several statistical crash data studies have found there to be little or no net safety benefit from the implementation of four-wheel ABS on passenger automobiles. Typically, these studies have found ABS to be associated with: 1. A statistically significant decrease in multi-vehicle crashes. 2. A statistically significant decrease in fatal pedestrian strikes. 3. A statistically significant increase in single-vehicle road departure crashes. The safety disbenefit due to the third finding approximately cancels the safety benefits from the first two findings.
Technical Paper

A Comprehensive Light Vehicle Antilock Brake System Test Track Performance Evaluation

1999-03-01
1999-01-1287
To determine if situations and/or conditions exist in which ABS-equipped vehicles do not perform as well as those without ABS, the braking performance of nine passenger vehicles was observed over a comprehensive array of driving conditions. For most maneuvers, on most surfaces, ABS-assisted stops yielded distances shorter than those made with the ABS disabled. The one exception was on loose gravel where stopping distances increased by an average of 27.2 percent overall. Additionally, the vehicular stability observed during testing was almost always superior with ABS. For the cases in which instability was observed, ABS was not deemed responsible for its occurrence.
Technical Paper

Methodology for the Safe and Economical Fatigue Design of Components in ABS/ETC Braking Systems Under Variable Amplitude Loadings

1999-03-01
1999-01-0366
The paper presents first how load spectra of antilock brake and electronic traction control systems (ABS/ETC) are obtained from braking pressure simulation in special test benches for particular vehicles of different customers. Subsequently, the measures for the derivation of a test spectrum under consideration of a reasonable test time reduction are described. Finally, the experimental and numerical procedures for fatigue life and safety assessments of the ABC/ETC hydraulic housings are presented.
Technical Paper

A Front Rail Design for Efficient Crush Energy Absorption

1995-10-31
1995-20-0016
Although there was a safety awareness from the earliest days of the automobile, systematic approaches to designing for safety became more widespread after 1950 when large numbers of vehicles came into use in both the United States and Europe, and governments in both continents undertook a widespread highway development. Industry response to safety objectives and also to government regulation has produced a large number of safety enhancing engineering developments, including radial tires, disc brakes, anti-lock brakes, improved vehicle lighting systems, better highway sign support poles, padded instrument panels, better windshield retention systems, collapsible hood structures, accident sensitive fuel pump shut-off valves, and other items. A significant development was the design of the energy absorbing front structures.
Technical Paper

Emerging Trends in Automotive Power Semiconductor Systems

1999-03-01
1999-01-0160
The increased worldwide demand for improved engine performance, emission control, diagnostics, safety, comfort and quality of drive is causing explosive growth in the amount of power semiconductors in automotive electronic systems. Discrete power semiconductors such as MOSFETs have been used for several years now in auxiliary functions like air bags, anti-lock brakes, seat belt pre-tensioners, engine management systems and so on. These are now considered standard features in many cars today. As the price and performance of power semiconductors improves, more and more sophisticated systems are being developed. New technologies in packaging are enabling the integration and modularisation of complete functions, further reducing overall systems size and cost, and increasing performance, reliability and usability.
Technical Paper

Experimental Approach for Evaluating Tire Characteristics and ABS Performance

2000-03-06
2000-01-0110
Chassis control systems, including ABS, traction control and vehicle stability control, utilize the available tire forces to improve vehicle acceleration, deceleration, handling and stability for active safety. Thus, it can be very beneficial to evaluate the tire force characteristics on actual road surfaces and use this information in the chassis control systems. In this paper, the research activities on evaluating the tire force characteristics and the performance of chassis control systems are introduced. The test procedure described for measuring the tire force characteristics on actual road surfaces using a test vehicle is relatively easy. The brake and side force characteristics are shown from the experimental data. The tire force characteristics during ABS braking were measured on various road surfaces. ABS performance is discussed based on the measured tire force characteristics.
Technical Paper

A New Dynamometer Test Rig to Develop Drive Lines for All-Wheel Driven Vehicles

1988-11-01
881736
To develop drivelines for four-wheel driven vehicles, the design for a new drive line test cell had to address the following key issues: Overall reduction in development time through reduction in testing time, quality improvement of test data and the ability to simulate road tests in the dynamometer cell. The paper first lists the major tasks to be performed by the test rig. In addition to driveline endurance tests, component interaction during operation is to be investigated for a wide variety of simulated driving conditions. The driveline is to be correctly loaded dynamically during acceleration and deceleration to test behavior under transient conditions. Tests typical for all wheel driven vehicles are to include variations in torque distribution between axles during rapid loading changes as experienced by a spinning wheel, engagement and disengagement of the 4-wheel drive, cornering etc.
Technical Paper

Antilock Brake System (M-ABS) Based on the Friction Coefficient Between the Wheel and the Road Surface

1990-02-01
900207
The conventional antilock brake systems (ABS) control the braking action according to the slip ratio between the wheel and road surface. We are developing another concept of ABS which is controlled based on the wheel-to-road surface friction coefficient. In this system the wheel speed sensors are not required but the friction coefficient detectors are provided. This system controls the brake fluid pressure in such a manner that the brake will always be applied at or near the maximum friction coefficient. As the results of the examination for verification it was found that our ABS functions as ABS preventing locking up of the wheels during braking process.
Technical Paper

The Design of Speed and Position Sensors in Conjunction with Bearings in Automotive Applications

1990-02-01
900206
The proliferation of electronic controls in automobiles has spurred developments in RPM and rotational position sensors and their packaging. The authors have developed custom packages of sensor systems for use in several automobile applications (Anti-lock Braking Systems (ABS), automatic transmissions, steering columns and ignition systems). These packages are characterized by (in their preferred configuration) “zero speed” capabilities, high resolution (100's of signals), digital output, -40°C to +150°C continuous temperature service, EMI, voltage spike and reverse voltage tolerance. The attainment of consistently high resolution and accurate signals is attributed to (1) the integration of sensors with bearings, (2) the development of state-of-the-art magnetization procedures in combination with optimal magnet materials and (3) the development of a general design model. All described designs have been tested for conformance with performance specifications.
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