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Technical Paper

A Driving Simulator Using Microprocessors

1988-03-01
871156
An inexpensive driving simulation system with sufficient fidelity has been developed. The system produces motion cues of four degrees of freedom, visual and auditory cues, and control feel on the steering wheel. This paper describes the features of this newly developed system and gives examples that demonstrate its effectiveness. The motion cues provided in this system are yaw, heave, and lateral and fore/aft accelerations. The lateral and fore/aft accelerations are simulated by tilting the simulator compartment. A computer-processed road image is given through a CRT monitor. The restoring torque of the steering wheel is produced by an electrical servosystem via a coil spring. Cruising sound is given in order to improve speed perception. Since the system uses digital computers, the vehicle characteristics are altered easily by merely rewriting the software. This enables us to simulate special vehicle dynamics such as front & rear wheel steering.
Technical Paper

A Study on the Performance of Guideway Bus Steering Control System

1988-03-01
871231
In this paper a computer simulation study on the effects of steering parameters on lateral dynamics of the guideway bus to contribute to a development practice of designing optimum steering control system are dealt with. A stability limit of vehicle lateral motion is analyzed and an emphasis is laid on the effects of moment of inertia of a conventional steering wheel and lateral elasticity of the guide rail which have proven to reduce the critical vehicle speed. It is pointed out conclusively that a normal bus equipped with additional simple guidance equipments can be guided smoothly on a simple guideway at adequately high vehicle speed.
Technical Paper

Fundamental Physics Behind New Suspension Concept for Automobiles

2000-05-01
2000-01-1647
The Transverse Leaf suspension with Superior Roll Axis is a new suspension concept for automobiles. It enables the load transfer during a turn to be more evenly redistributed between the two wheels on the same axle thus optimizing its tires lateral force capabilities. The TLSRA concept is made up of a single transverse leaf spring linking the middle of the sprung mass to the outer end of 2 transverse suspension arms per axle. Those transverse arms are mounted close to the middle of the sprung mass with their attachment points located above the mass centroïd. Each wheel assembly is mounted directly onto the free end of its respective suspension arm. Because body roll is now counteracting vertical load transfer during transient and permanent operating conditions, this suspension enables designers to keep spring stiffness low without compromising road handling.
Technical Paper

An Automatic Vehicle Controller for Stability and Handling Tests

2000-05-01
2000-01-1627
An automatic vehicle controller (AVC) which was specified, designed, fabricated, installed and used on a variety of vehicles, including automobiles, light trucks, and sport utility vehicles is described. The AVC controls the vehicle's steering, and input waveforms of virtually any type or complexity can be specified from computer files containing steering wheel angle commands as functions of time. Also, algorithms which use motion sensor feedback in the steering control logic can be programmed. Throttle and brake controls can also be provided.
Technical Paper

Elimination of Roll, Squat, and Dive Through Biased Suspension Response

2000-05-01
2000-01-1632
Conventionally sprung vehicles are subject to rolling and pitching of the sprung load as the vehicle corners and accelerates, respectively. Designs which incorporate active elements seek to control these movements, frequently resulting in compromised performance or reduced fuel economy. This paper considers the possible replacement of conventional springs, shocks, and anti-sway bars with specified fluid spring components. The fluid spring components offer biased response to dynamic load variations in the following manner: provide support of the sprung load equal to the magnitude of the load at each moment, and either compressing readily to absorb upward forces originating in the wheel assembly which exceed the magnitude of the load at that moment, or extending rapidly to provide support equal to the magnitude of the load at that moment, in the event the wheel assembly tracks through a hole.
Technical Paper

Dynamics Simulation Research on Rigid-Elastic Coupling System of Car Suspension

2000-05-01
2000-01-1622
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.
Technical Paper

NEWPED - A Stealth Auxiliary Engine in a Bicycle with Very Low Noise, Low Pollutant Emission and Good Fuel Economy

1999-09-28
1999-01-3280
The development history of a 30cc 2-stroke engine power unit in the covered rear wheel for retrofit into standard bicycle chassis. The rear wheel acts as cooling fan for the air cooled long stroke engine with catalyst exhaust system, autochoke carburetor, autolube oil pump, electric start and inertia start, single speed automatic transmission and 7 speed hub final drive. The space in the rear wheel contains intake air filter, exhaust system, fuel tank, oil tank and engine with drive train, the complete engine being only 94mm wide. The complete covered power unit is nearly undetectable as the rear wheel covers resemble road racing bicycles. There is very low stationary and pass-by noise (64 db[A]), no exhaust gas opacity or smell, very low vibration level and very good fuel economy up to 133 km/l.
Technical Paper

Analysis of Automotive Handling Based on Tire Cornering Properties in Non-Steady State Conditions

1999-11-15
1999-01-3758
Non-steady state (NSS) tire cornering properties show obvious differences from steady state (SS) tire cornering properties. A two-DOF automobile model with steer angle as an input is established based on the known NSS tire model considering complex carcass deformation. The tire model can certainly be applied to modelling of a multi-DOF automobile system. The frequency responses of lateral acceleration and yaw rate are then derived. An evaluation index, amplitude-frequency characteristic of relative error (AFCRE), is used to analyze the influences of NSS front wheels (FW) and/or rear wheels (RW) on automotive handling. The influences of NSS FW are much greater than those of NSS RW only on automotive handling. The established automobile model can also be applied to other similar studies of vehicle dynamics.
Technical Paper

Differential Torque Steering for Future Combat Vehicles

1999-11-15
1999-01-3740
This paper discusses the evolution of skid steer systems, and takes a new look at the advantages and implications of designing future ground combat vehicles with all non-steerable wheels. The traditional “skid steer” designation of such vehicles is dropped in favor of the more descriptive phrase “differential torque steer” vehicle. The possible advantages of such systems for combat vehicle application are presented along with a synopsis of various past modeling, simulation, and vehicle hardware efforts to evaluate skid steer systems. A comprehensive vehicle modeling effort for a differential torque steer system is then presented. Two independent implementations of the model are presented along with model verification and validation results. Finally the model is used to evaluate potential turning performance for a 4×4 vehicle with differential torque steer.
Technical Paper

Optimal Mass and Geometric Parameters in Multi-Wheel Drive Trucks for Improved Transport and Fuel Efficiency

1999-11-15
1999-01-3733
To develop better performing vehicles, for ground transportation, it is necessary to improve the theory in vehicle dynamics for choosing suitable mass and geometric parameters for highway as well as for off road trucks. A new approach is required for choosing such optimal mass and geometric parameters. The present paper is devoted to this problem. A new method for synthesis of mass and geometric parameters is introduced here. The method allows us to synthesize the parameters in such way as to provide a vehicle with the best transport efficiency under various road surface conditions. Constraints such as limitations on these parameters, vehicle running modes, mass and geometric parameters are included in the model. Furthermore other constraints for vehicle running abilities which are dependent on mass and geometric parameters, as well as an algorithm for synthesizing mass and geometric parameters are also included in the paper for pre-optimization process.
Technical Paper

A New EPS Control Strategy to Improve Steering Wheel Returnability

2000-03-06
2000-01-0815
This paper proposes a new Electric Power Steering (EPS) control strategy that enables improvement to steering-wheel returnability. Using a conventional EPS controller, frictional loss torque in the steering mechanism reduces steering-wheel returnability, which drivers occasionally perceive as unpleasant. This phenomena occurs in any EPS system regardless of motor type or mounting location. To improve steering-wheel returnability for EPS-equipped vehicles, we developed a new control strategy based on estimation of alignment torque generated by tires and road surfaces. This proposed control strategy requires no supplemental sensors like steering-wheel angle or motor-angle sensors. We experimented with this proposed control algorithm using a test vehicle and confirmed that it enables improved steering wheel returnability and also better on-center feeling.
Technical Paper

Presentation of Flow Field Investigation by PIV on a Full-Scale Car in the Pininfarina Wind Tunnel

2000-03-06
2000-01-0870
Particle Image Velocimetry (PIV) is a recent measuring technique, which has been used up to now mainly by University Laboratories in small-scale wind tunnels and by Aeronautical Research Centers in small and large facilities. Its use in full-scale automotive testing is not common. It is not so easy, often rather difficult, due to a number of problems, sometimes of practical nature, sometime caused by technology limitations. This paper reports the results of some tests, carried out by CIRA (Centro Italiano Ricerche Aerospaziali) in the Pininfarina wind tunnel on a full-scale car, in the frame of the European Thematic Network “PIVNET”. A description of the test set up, of the instrumentation used for these tests, as well as an analysis of the advantages provided by this technique and of its present limitations, are reported. During the tests, in order to outline the potential of this measuring technique, some specific areas of the car flow field, have been investigated.
Technical Paper

Air Bag Parameter Study with Out-Of-Position Small Female Test Devices

2000-06-19
2000-01-2204
The development of the Advanced Restraint System has lead to an innovative way in which we evaluate the systems effect on the occupant. This paper presents some initial investigation into the driver airbag system that consists of an inflator, cushion fold, tear seam pattern, and offset of the airbag cover to steering wheel rim plane. An initial DOE is reviewed to establish significant parameters and to identify equations for further investigation.
Technical Paper

An Evaluation of Vehicle Steering Arrangement with Dexterity Measures of Virtual Human

2001-06-26
2001-01-2109
Four ellipsoid-type dexterity analyses, which have been popular in the field of robotics, were applied to evaluate vehicle driver's steering arrangement. The Human was modeled as three-dimensional rigid bodies. Their length and inertia properties were based on anthropometric data. The newly defined measures were introduced as an effective radius of each ellipsoid along the steering direction, divided by a degree of agreement between the principal axes of the ellipsoid and those of the steering wheel. Sensitivity analyses were done with regard to the steering wheel location in a vertical plane and inclination, and seat back angle. Measures from dynamic dexterity ellipsoids, in particular the measure based on kinetic energy, nearly correspond to the traditional region of steering wheel arrangement from subjective judgement. Optimum inclination angle depending on seat back angle was calculated for three different sizes of drivers with the measures from dynamic dexterity ellipsoids.
Technical Paper

Frequency Domain Sensitivity Analysis of Yaw Rate and Lateral Acceleration Response of Front Wheel Steering Vehicles

2001-01-10
2001-26-0035
A vehicle's lateral performance and handling characteristics are most important while negotiating a turn. In this paper sensitivity analysis of lateral acceleration and yaw rate for front wheel steering vehicles is carried out in the frequency domain using the first order standard and first order logarithmic sensitivity functions. A simple two degree of freedom model is used for deriving amplitude ratio and phase angle for both yaw rate and lateral acceleration. Vehicle mass, yaw moment of inertia, front and rear tire cornering stiffnesses and distance from the front axle to the centre of gravity are the design variables considered. This study predicts that the strongest parameter is the location of the centre of gravity and the weakest parameters are mass and yaw moment of inertia.
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

Fatigue Strength of a Rim Model with FEM Using a New Approximation Technique

2001-10-01
2001-01-3339
In this study, a domestic wheel rim model has been modeled using FEM in order to calculate its fatigue strength. In other words, a different approximation algorithm has been developed to obtain service life of the rim. The effects of dynamic and static loads on the rim have been calculated and included to the FEM analysis. As a new approximation technique, during the service life of a vehicle under dynamic loads arising from the road conditions as taking into account, load spectrum has been constituted. In the design spectrum that has been utilized in our calculations, instead of using straight good road conditions, other fifty percent of forces that have been corresponding lifetime of the vehicle, accepted as hundred percent of dynamic and static forces caused by bad road conditions acting on the rim. As a result of this study, the calculated results have been compared to the experimental data taken from literature review.
Technical Paper

About Interrelation Between the Tire Grip Properties and the Wheel Sliding

2001-10-01
2001-01-3338
The investigation is concerned with dependencies between a friction coefficient of the tire with a road, μ, and wheel slip, s. The analysis of μ-s-dependencies is given in the paper. The conventional approach to their presentation contains some discordance with real physical processes. On the basis of the external friction theory it is possible to offer another concept of potential μ-s-curves. The potential μ-s-curve is a function of the deformative, adhesion and transverse components of tire grip, the absolute slip velocity and the road reaction. Over the interrelation character of the given components it is possible to evaluate a current road-operational situation. In addition the recommendations for practical use of the potential μ-s-dependencies for the Systems of Active Safety are given.
Technical Paper

Aviation Safety Training - A Failure In Motion

2001-09-11
2001-01-2635
What was always referred to as pilot error or human error is now considered to be an error by the organization that trained (or failed to train) the operator or front-line person. Although mistakes due to human error will never be completely eradicated, every attempt must be made to reduce these errors to their lowest possible number. Unfortunately, changing human behavior is difficult at best. The typical aviation safety training program does not use all available strategies to make these needed changes in behavior. Even one small omission can dramatically reduce the effectiveness of a training program. Instead of cranking out hour after hour of traditional lecture-type training, changes must be made in methodology and techniques. The training wheel is continually cranked, but whether it does any good is usually “hoped for” and guessed at. Aviation safety training is, for so much time and effort, a failure in motion.
Technical Paper

Fatigue Technology in Vehicle Development

2001-03-05
2001-01-4081
Modern approaches to durability assurance in ground vehicle design are reviewed in the context of recent developments in computer-based analytical and experimental tools for use by designers and development engineers. Examples, using an automotive wheel assembly, are presented to illustrate the application of fatigue analysis in product development. Major challenges associated with the linking of various design tools into integrated networks appropriately configured for industrial problem solving are discussed along with an assessment of the potential benefits to be gained from such integration.
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