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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

Design of Front Wheel Active Steering for Improved Vehicle Handling and Stability

2000-05-15
2000-01-1619
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.
Technical Paper

Improved Heavy Vehicle Wheel Dynamics Model Using MATLAB/SIMULINK

1999-11-15
1999-01-3707
The accuracy of existing rotational wheel dynamics models has been found to be insufficient for heavy vehicle Antilock Braking System (ABS) and Electropneumatic Braking System (EBS) simulation, specifically when wheelspeeds are at or near zero but the vehicle speed is not. Control strategies specific to ABS and EBS, the low frequency response of pneumatic actuation, and the practice of using fewer modulators than braked wheels require that a vehicle model be able to handle lockedwheel scenarios accurately. Commercially available models have been found unsatisfactory in this regard, and technical literature has not been found to address this issue.
Technical Paper

New Traction-Optimized Front Axle Limited-Slip Differential for AWD All-Terrain-Vehicle

2000-03-06
2000-01-1155
An advancement in All-Terrain-Vehicle (ATV) traction control has entered the market place with the debut of the 1999 Bombardier Traxter. The basis for this is the progressive front axle limited-slip differential. The Visco Lok‚ differential provides a speed-sensing progressive traction-optimized characteristic for maximum off-road performance. This paper includes an overview of the vehicle driveline system, functional characteristics of the differential, and torque transfer requirements.
Technical Paper

Characterization of Emissions from Hybrid-Electric and Conventional Transit Buses

2000-06-19
2000-01-2011
Hybrid-electric transit buses offer benefits over conventional transit buses of comparable capacity. These benefits include reduced fuel consumption, reduced emissions and the utilization of smaller engines. Factors allowing for these benefits are the use of regenerative braking and reductions in engine transient operation through sophisticated power management systems. However, characterization of emissions from these buses represents new territory: the whole vehicle must be tested to estimate real world tailpipe emissions levels and fuel economy. The West Virginia University Transportable Heavy Duty Emissions Testing Laboratories were used to characterize emissions from diesel hybrid-electric powered as well as diesel and natural gas powered transit buses in Boston, MA and New York City.
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

OSEKtime: A Dependable Real-Time Fault-Tolerant Operating System and Communication Layer as an Enabling Technology for By-Wire Applications

2000-03-06
2000-01-1051
The new generation of drive-by-wire systems currently under development has demanding requirements on the electronic architecture. Functions such as brake-by-wire or steer-by-wire require continued operation even in the presence of component failures. The electronic architecture must therefore provide fault-tolerance and real-time response. This in turn requires the operating system and the communication layer to be predictable, dependable and composable. It is well known that this properties are best supported by a time-triggered approach. A consortium consisting of German and French car manufacturers and suppliers, which aims at becoming a working group within the OSEK/VDX initiative, the OSEKtime consortium, is currently defining a specification for a time-triggered operating system and a fault-tolerant communication layer.1 The operating system and the communication layer are based on applicable interfaces of the OSEK/VDX standard.
Technical Paper

Design Issues of the Switched Reluctance Motor Drive for Propulsion and Regenerative Braking in EV and HEV

2001-08-20
2001-01-2526
There is a growing interest in electric and hybrid electric vehicles (EV and HEV) due to their high efficiency and low emission. In EV and HEV, the characteristic of the traction motor is essential for the performance and efficiency of the EV and HEV. In this paper, the advantages of the extended constant power range characteristic of the traction motor for both propulsion and regenerative braking are analyzed. Simulation results are presented to verify the conclusions. Due to its several inherent advantages, especially its capability of having an extended constant power range, Switched Reluctance Motor (SRM) is proposed as the candidate of the traction motor in EV and HEV. The design methodology of SRM for achieving an extended constant power range and the control strategy of SRM for regenerative braking in EV and HEV are presented.
Technical Paper

Measuring Yaw Rate with Accelerometers

2001-08-20
2001-01-2535
This paper presents a new way of measuring yaw rate of the vehicle using two accelerometers. Measurement of yaw rate is inevitable for vehicle stability control systems for contemporary high performance sedans and automatic steering control systems for intelligent vehicles. Compared with accelerometers, the cost of rate gyros used to measure the yaw rate is significantly higher. As an economical software solution to replace the high-cost rate gyros with minimal additional hardware, an algorithm to obtain yaw rate using two accelerometers is proposed in this paper.
Technical Paper

Development Experience with Steer-by-Wire

2001-08-20
2001-01-2479
Recent advances in dependable embedded system technology, as well as continuing demand for improved handling and passive and active safety improvements, have led vehicle manufacturers and suppliers to actively pursue development programs in computer-controlled, by-wire subsystems. These subsystems include steer-by-wire and brake-by-wire, and are composed of mechanically de-coupled sets of actuators and controllers connected through multiplexed, in-vehicle computer networks; there is no mechanical link to the driver. This paper addresses fundamental benefits and issues of steer-by-wire, especially those related to automated vehicle control and steering feel quality as perceived by the driver.
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

Simulation of Energy Conversion in Advanced Automotive Vehicles

2001-10-01
2001-01-3341
Propulsion systems for future advanced automotive vehicles have to be optimised for maximum fuel conversion efficiency. In such a case, hybrid electric propulsion system seems to be most useful, due to the following facts: Hybrid Electric Vehicle (HEV) has energy storage (secondary energy source) which allows decreasing required peak value of power from the prime mover, that is the Internal Combustion Engine (ICE); energy boosting allows to decrease ICE's or Fuel Cells' (FC) size and mass considerably; because of the limited range of ICE operation area, maximum fuel conversion efficiency can be achieved after optimization; emissions can be reduced - ICE never idles; application of a direct electromechanical drive with the DC/AC commutator motor or the motorized and generatorized wheels (M&GW) enables an advanced automotive vehicle to ride with regenerative braking.
Technical Paper

Electric Vehicle Propulsion System Prototype Based on Fuel Cell and Switched Reluctance Motor - Generator

2001-03-05
2001-01-3889
This paper shows some aspects of the development of a fuel cell based propulsion system prototype for electric vehicles. A switched reluctance motor/generator - SRM/G - with 3 phases, 6 stator poles and 4 rotor poles is connected to the DC link bus through an asymmetric half-bridge converter which is fed by a PEM (Proton Exchange Membrane) fuel cell. The control functions of this drive are performed by a 8 bit microcontroller. This system allows the studies of the motoring, generating and regenerative braking operations aiming the development of the necessary knowledge to design propulsion systems for several kinds of vehicles.
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

Robust Vehicle Stability Controller based on Multiple Sliding Mode Control

2001-03-05
2001-01-1060
Vehicle stability control system can enhance the vehicle stability and handling in the emergency situations through the control of traction and braking forces at the individual wheels. Because this system needs to handle the nonlinear and complex vehicle dynamics, the controller is required to have the robustness and the simple structure for practical applications in order to achieve the desired performance. This paper proposes a new controller based on the multiple sliding mode control theory for vehicle stability control system to satisfy these requirements. The proposed controller for the lateral motion makes use of both the sideslip angle and the yaw rate. It brings the vehicle sideslip angle and the yaw rate close to the desired ones so that the vehicle dynamics becomes stable and the vehicle traces the desired course even in limit cornering.
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

Design of Observer for Vehicle Stability Control System

2000-06-12
2000-05-0230
Vehicle stability control system is a new idea which can enhance the vehicle stability and handling in the emergency situation. This system requires of the yaw rate, side slip angle, and road friction in order to control the traction force and the braking force at the individual wheels. This paper proposes an observer for vehicle stability control system. This observer consisted of the state observer for vehicle motion identification and the road condition estimator for the identification of the road friction coefficient. The state observer uses 2 degree-of-freedom bicycle model with the Dugoff tire and estimates the system variables based on the Kalman filter. The road condition estimator uses the same vehicle model and identifies the tire-road friction based on the recursive least square method. Both estimators make use of each other information.
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

ADM A NEW DRIVE-TRAIN MANAGEMENT

2000-06-12
2000-05-0389
The new drive-train system Automatic Drive-Train Management (ADM) controls all traction systems present in a vehicle. Applications include the all wheel drive feature in transfer cases and differential locks in axles. Compared to manually operated or automated traction control systems ADM has the advantage of transferring 100 percent of the torque automatically. The range of application for the ADM system would be a 4×2 truck tractor to a 6×6 off-road vehicle. A key feature of the ADM system is the synchronized engagement of gears in a two-speed transfer case while the vehicle is moving.
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