Tire Grip Research Articles

Passive vehicle suspensions employing inerters with multiple performance requirements

This paper investigates passive vehicle suspensions with inerters by considering multiple performance requirements including ride comfort, suspension deflection and tyre grip, where suspension deflection performance is novelly considered which is formulated as a part of objective functions and a constraint separately. Six suspension configurations are analyzed and the analytical solutions for each performance measure are derived. The conditions for each configuration to be strictly better than the simpler ones are obtained by presenting the analytical solutions of each configuration based on those of the simpler ones. Then, two stages of comparisons are given to show the performance limitations of suspension deflection for passive suspensions with inerters. In the first stage, it is shown that although the configurations with inerters can improve the mixed performance of ride comfort and tyre grip, the suspension deflection performance is significantly decreased simultaneously. In the second stage, it is shown that for passive suspensions with inerters, suspension deflection is the more basic limitation for both ride comfort and tyre grip performance by doing comparisons among mixed ride comfort and suspension deflection optimization, mixed ride comfort and tyre grip optimization, and mixed suspension deflection and tyre grip optimization. Finally, the problem of mixed ride comfort and tyre grip performance optimization with equal suspension deflection is investigated. The limitations of suspension deflection for each configuration are further highlighted.

Gradeability for Automobiles

The demand for transport has been growing rapidly and the footprints of roads have been widespread to areas which were previously inaccessible, especially hilly areas. Road inclinations are not always at zero. Vehicles should have the capability to take gradients even on full loads. The Gradeability of a vehicle is dependent on multiple factors such as the type of road surface, weight of the vehicle, tractive effort at the wheels, tire grip (at low speeds the aerodynamic drag is ignored). Since a vehicle should be ready to be driven on all types of terrains, tractive effort and tire grip become the deciding factors. This paper presents a method to determine the gradeability and enhance it to the required scale.

1B23 Verification and optimization of Formula SAE suspension employing Inerter mechanism(The 12th International Conference on Motion and Vibration Control)

In generally, a suspension system needs to be soft to insulate against road disturbances and hard to insulate against load disturbances. It cannot achieve with a traditional passive suspension that only considered to the stiffness and damper. On other hands, the formula cars need high tire grip on racing challenge by reducing rolling displacement at corner or double change lands with the simplest suspension dynamics system. In this study, the paper clarifies some issues related to suspension system with inerter to reduce displacement and rolling angle under impact from road disturbance on Formula SAE Car. In this paper, we integrate some kinds of suspension system with inerter on quarter-car and half-car models. We propose some new designs, which have some advantages for suspension system by improving dynamics. We optimize design of model based on the minimization of cost functions for roll dynamics, by reducing the displacement transfer and the energy consumed by the inerter. The base model is a passive suspension model then we carried out quarter-car and half-car model with different parameters; they show the benefit of the inerter in proposal suspension system. The advantage of research is integration a new mechanism, the inerter; this system can improve the vehicle oscillation.

Tyre–road grip coefficient assessment – Part II: online estimation using instrumented vehicle, extended Kalman filter, and neural network

The main objective of this work is to determine the limit of safe driving conditions by identifying the maximal friction coefficient in a real vehicle. The study will focus on finding a method to determine this limit before reaching the skid, which is valuable information in the context of traffic safety. Since it is not possible to measure the friction coefficient directly, it will be estimated using the appropriate tools in order to get the most accurate information. A real vehicle is instrumented to collect information of general kinematics and steering tie-rod forces. A real-time algorithm is developed to estimate forces and aligning torque in the tyres using an extended Kalman filter and neural networks techniques. The methodology is based on determining the aligning torque; this variable allows evaluation of the behaviour of the tyre. It transmits interesting information from the tyre–road contact and can be used to predict the maximal tyre grip and safety margin. The maximal grip coefficient is estimated according to a knowledge base, extracted from computer simulation of a high detailed three-dimensional model, using Adams® software. The proposed methodology is validated and applied to real driving conditions, in which maximal grip and safety margin are properly estimated.

On-board wet road surface identification using tyre/road noise and Support Vector Machines

Changes in weather have a major influence on driving safety. On wet pavement, tyre grip is reduced and drivers must adapt their driving style accordingly. The correct operation of this adaptation mechanism depends on the perception the driver has of the asphalt status. Due to certain effects, this perception does not always correspond with reality. To improve this perception, it is essential to inform the driver about the asphalt status, efficiently and as quickly as possible. This could be achieved by installing an asphalt status detection system on the vehicle itself. The system could display asphalt status information in the vehicle’s console, allowing drivers to adapt their driving style accordingly.In this paper we propose an asphalt status classification system based on real-time acoustic analysis of tyre/road noise. The proposed system uses a practical approach that allows it to be integrated into a real vehicle. We present the system architecture used to measure the noise and the signal processing algorithms used for the classification of the asphalt state. A practical implementation of the proposed system has been developed and tested. For this preliminary prototype, only wet and dry asphalt states have been covered. Obtained wet/dry classification results have been reported, showing very high success rates.

A Modular Race Tire Model Concerning Thermal and Transient Behavior using a Simple Contact Patch Description

ABSTRACT The potential of a race tire strongly depends on its thermal condition, the load distribution in its contact patch, and the variation of wheel load. The approach described in this paper uses a modular structure consisting of elementary blocks for thermodynamics, transient excitation, and load distribution in the contact patch. The model provides conclusive tire characteristics by adopting the fundamental parameters of a simple mathematical force description. This then allows an isolated parameterization and examination of each block in order to subsequently analyze particular influences on the full model. For the characterization of the load distribution in the contact patch depending on inflation pressure, camber, and the present force state, a mathematical description of measured pressure distribution is used. This affects the tire's grip as well as the heat input to its surface and its casing. In order to determine the thermal condition, one-dimensional partial differential equations at discrete rings over the tire width solve the balance of energy. The resulting surface and rubber temperatures are used to determine the friction coefficient and stiffness of the rubber. The tire's transient behavior is modeled by a state selective filtering, which distinguishes between the dynamics of wheel load and slip. Simulation results for the range of occurring states at dry conditions show a sufficient correlation between the tire model's output and measured tire forces while requiring only a simplified and descriptive set of parameters.

Tire grip identification based on strain information: Theory and simulations

A novel technique for the identification of the tire–road grip conditions is presented. This is based on the use of strain information inside the tire, from which relevant characteristics of the tire–road contact can be extracted also through a factor named area slip ratio. This process forms the basis of a technology for grip identification that requires a new model of the tire dynamics. The model permits to determine closed form analytical relationships between the measured strain and the area slip ratio. On this basis, a procedure that can extract the contact kinematic parameter from the time history of the internal strain of the rolling tire is presented. Numerical simulations offer the chance to validate the identification algorithm.

The influence of non-carcinogenic petroleum-based process oils on tire compounds’ performance

High aromatic oils which have been widely used as process oils in tire the industry contain high concentrations of polycyclic aromatic hydrocarbons (PAHs). These aromatic compounds (PAHs) have proved to be carcinogenic as well as posing a threat to the environment. Since the beginning of 2010, the use of high aromatic process oils has been banned under the EU regulation 1907/2007 commonly called REACH (registration, evaluation, authorization and restriction of chemicals). The so-called regulation has given rise to challenges to the oil and tire industries in replacing high aromatic process oils with safer alternatives. In the present work, four types of low aromatic petroleum-based process oils, namely mild and high-viscosity naphthenic oils (LNAP and HNAP), treated distillate aromatic extract (TDAE) and mildly extracted solvate (MES), were investigated and their effect on plasticization and durability properties of two different low and high oil-extended tire formulations were evaluated. The compatibility of oils with rubber was investigated as well. The results showed that a number of properties such as abrasion resistance and tire rolling resistance were improved by using non-carcinogenic oils, while tire grip properties were declined. Considering oil–rubber compatibility, TDAE and MES were found to be more compatible with rubbers.

Support Effects of the Haptic Throttle Grip by the Friction Circle on the Driving Wheel

Recently, there have been many reports about development of Human Machine Interface (HMI) which used a visual or auditory display to improve driver assist. For a motorcycle, it is suitable to use a haptic display for rider assist, since there are many disturbances in open-air situation such as sunshine and surrounding noise. Therefore, a test vehicle based on a large motorcycle equipped with the haptic throttle grip that is connected to a motor by gear, an original ECU to control the motor, and a lean angle sensor to calculate the lateral force of the motorcycle was developed. To inform surplus driving force warning, the throttle grip, a haptic display outputs additional return torque estimated by the friction circle and ellipse with the lateral force of the motorcycle. One of the purposes of this torque is that it informs the rider to decelerate when the motorcycle state of movement is around the limit of tire grip, and another purpose is that it leads to return the throttle grip to decelerate. For both purposes, the intuitive signal which adds return torque was selected to avoid misunderstanding. As the result of riding tests, all of the riders were able to recognize the signal and understood the request from the motorcycle. It became clear that this system was able to offer the information of surplus driving force warning, and to support the throttle grip operation. Language: en

The effect of tire grip on learning driving skill and driving style: A driving simulator study

There is a need for training methods that improve the driving skill and driving style of novice drivers. Previous research in motor learning has shown that degrading the task conditions during practice can enhance long-term retention performance. Inspired by these findings, this study investigated the effects of the tire-road friction coefficient on learning a self-paced lane-keeping task in a driving simulator. A sample of 63 young and inexperienced drivers were divided into three groups, low grip (LG), normal grip (NG) and high grip (HG), who practiced driving with a friction coefficient of 0.45, 0.90, and 1.80, respectively. All groups drove six 8 min sessions on a road with curves in a rural environment: four practice sessions, an immediate retention session, and a delayed retention session on the next day. The two retention sessions were driven with normal-grip tires. The results show that LG drove with lower speed than NG during practice and retention. Transferring from the last practice session to the immediate retention session, LG's workload decreased, as measured with a secondary task, whereas HG's workload increased. During the immediate retention session, LG had less road departures than HG, but HG drove closer to the lane center in curves than the other two groups. HG reported elevated confidence during practice, but not in retention. In conclusion, this simulator-based study showed that practicing with low-grip tires resulted in lower driving speeds during retention tests, an effect which persisted overnight. These results have potential implications for the way drivers are trained.

Vibration suppression using two-terminal flywheel. Part II: application to vehicle passive suspension

The two-terminal flywheel introduced in Part I is suggested to be attached in parallel to the suspension strut whose vibration suppression performance improvement is accordingly investigated in this paper. The passenger comfort, tire grip and suspension deflection are respectively taken as the vibration suppression indices to design the optimal parameters of the proposed and conventional passive suspensions. The optimal single-objective performances of both suspensions arecompared to each other in actual dynamic parameter ranges. Due to the three conflicting and non-commensurable performance objectives, the Chebyshev goal programming approach is subsequently applied to find a multi-objective compromise for a design case. The non-ideal factors of the inverse screw transmission mechanism, which is modeled in Part I, are also taken into consideration to discuss the influence on the vibration suppression performance. The resultsshow that, owing to the presence of the two-terminal flywheel, the proposed suspension employing this novel component significantly outperforms the conventional one in terms of both passenger comfort and tire grip, with practically identical suspension deflection performance.

Analytical solutions for optimal ride comfort and tyre grip for passive vehicle suspensions

The paper derives analytical solutions for the global optimum of the ride comfort and tyre grip performance measures for a quarter-car vehicle model optimised both individually and in combination. The solutions are derived for six simple suspension networks comprising one or two springs, one damper and possibly one inerter. The solutions are functions of four vehicle parameters: the sprung mass, the unsprung mass, the tyre stiffness and the static stiffness, of the suspension.

左右独立駆動制御による前輪タイヤ余裕度向上(自動車・二輪車の運動と制御(1),OS2 交通・物流機械のダイナミクス(振動,制御を含む))

This paper investigates the improvement of front tire grip margin by using Direct Yaw-moment Control (DYC) which is designed from the viewpoint of tire force usage. The micro-scale electric vehicle 'NOVEL' is equipped with two in-wheel-motors at rear axle and their motor torques can be controlled independently to achieve the DYC. In this paper, the DYC, which control objective is determined as Neutral-Steer(NS) characteristics, is designed with the application of yaw moment following control. Finally, the effect of the DYC on improvement of front tire grip margin is proved by NOVEL on J-turn test.

The intelligent systems of automotive active safety

Abstract The subject of research is the idea of creation automobile systems of active safety basing on predictable use of potential possibilities of a wheel coupling with a road. Together with the generally accepted dependencies between the tire grip µ wheel slip, s, it is expedient to use potential µ-s-curves which can be deduced, having applied some postulates of the friction theory to the process of wheel-road interaction. In the work the basic dependencies for qualitative estimation of the specified components are given. As the result the concept of an intelligent system of active safety which is based on the control philosophy of predictable use of a tire grip is offered.

THE INTELLIGENT SYSTEMS OF AUTOMOTIVE ACTIVE SAFETY

The subject of research is the idea of creation automobile systems of active safety basing on predictable use of potential possibilities of a wheel coupling with a road. Together with the generally accepted dependencies between the tire grip µ wheel slip, s, it is expedient to use potential µ-s-curves which can be deduced, having applied some postulates of the friction theory to the process of wheel-road interaction. In the work the basic dependencies for qualitative estimation of the specified components are given. As the result the concept of an intelligent system of active safety which is based on the control philosophy of predictable use of a tire grip is offered.

A New Carbon Black-Rubber Coupling Agent to Improve Wet Grip and Rolling Resistance of Tires

Abstract The compound p-aminobenzenesulfonyl azide was developed as a new type of carbon black to rubber coupling agent. Its addition to rubber compounds increases resilience and moduli while reducing abrasion loss. The behavior of this coupling agent is confirmed by the dynamic mechanical response of the vulcanizates—the rubber Tg is shifted to higher temperatures. Rubber compositions containing this coupling agent may be used in tire treads to reduce rolling resistance and improve wet skid resistance. These attributes were estimated from dynamic property measurements.

AVTOTEXNİKİ EKSPERTİZADA İSTİFADƏ OLUNAN ƏSAS İLKİN GÖSTƏRİCİLƏRİN (PARAMETRLƏRİN) TƏKLİF OLUNAN TƏSNİFATI

Abstract. In the production of autotechnical expertise in cases of traffic accidents, it often becomes necessary to select the technical parameters (indicators) used in the calculations. For the correct selection and determination of the value of technical parameters, it is necessary to compile lists of them (the most frequently used ones) and classify the factors influencing them, when choosing their value from appropriate sources. We believe that the proposed classification of the mentioned indicators (parameters) would provide appropriate help to students studying in relevant specialties in higher schools and young specialists who started working in the field of auto-technical expertise in terms of their study and correct application. Keywords: autotechnical expertise, technical parameters, road surface, deceleration, tire grip coefficient

Interface study of rubber-ice friction

To further understanding of road tyre grip on icy roads, laboratory equipment has been developed to study the contact interface formed between rubber and ice. It became clear that rubber can adhere well to cold ice but, on ice near its melting point, adhesion and friction are lost. The evidence presented here suggests that this loss is determined more by the properties of the ice than by the properties of the rubber.

Rubber-ice friction and vehicle handling

Motorists are aware of the low friction of rubber on ice, but they may not know that the colder the ice the less slippery it becomes. Any improvements in tyre grip to ice are welcome both for safety and the ability to move on an incline. To assist in the design of winter tyres MRPRA have for many years been skid testing tyres of novel rubber compounding and making laboratory studies of the mechanism of rubber-ice friction.

Tire to Wet Road Friction at High Speeds

Abstract The general problem of loss of tire grip on wet road surfaces is discussed. The initial section of the paper covers a description of testing techniques employed for the investigations reported. These include both road and indoor rig techniques developed to study limiting tire braking and cornering properties under a wide range of operating conditions. The level of friction between a tire and a wet road is primarily related to the ability to remove a water film from the ground contact area. The contact area is considered to be separated into three effective zones. Initially the ‘bulk’ of the film is displaced leaving a thin residual film to be penetrated at, or absorbed from, the interface before substantially dry contact can be established. The size of this dry area, at the rear of the contact zone, has an overriding control on the level of available friction and depends on the time occupied in displacing the water film in the frontal zones. An increase in the peripheral speed of the tire reduces the time available for water displacement and effectively shortens the area of actual ground contact. In the limiting condition the vertical load on the tire becomes entirely supported on the water film and the condition of aquaplaning exists. The requirements for this condition to occur are briefly discussed. Tread pattern and road surface design are shown to exert a considerable influence on the rate of water displacement from the contact area and hence on the relative sizes of the water supported zones. The forces developed in the dry zone at the rear of the ground contact depend on the frictional characteristics of the tread material. A section of the paper considers the wide scale effects of tread pattern, tread material, and road surface characteristics and discusses the nature of the interactions between these three variables. Some results of recent studies related to different types of tread pattern, specific pattern design features, and the effect of tire casing construction are included and future potential development of the tire contribution is reviewed.