Front Tire Research Articles

Multi-Objective Optimization of Vehicle Suspension Parameters Considering Various Road Classes

Abstract Vehicle suspension optimization for various road classes travelled at different velocities is performed. Road excitation is modeled using a first order shaping filter. A half-car model is adopted to simulate the vehicle’s vertical dynamics. The excitation time delay between the rear and the front tire is modeled using Pade approximation. Suspension parameters are optimized using a random search method with respect to “comfort” and “sporty driving” considering the design constraints of the suspension and road holding and maximum suspension travel constraints. Optimal suspension parameters suitable for various road classes and vehicle velocities have been chosen.

Identification of Linear Tire Cornering Stiffness Using Subspace Methods

In this paper, subspace identification methods are proposed to estimate the linear tire cornering stiffness, which are only based on the road tests data without any prior knowledge. This kind of data-driven method has strong robustness. In order to validate the feasibility and effectiveness of the algorithms, a series of standard road tests are carried out. Comparing with different subspace algorithms used in road tests, it can be concluded that the front tire cornering stiffness can be estimated accurately by the N4SID and CCA methods when the double lane change test data are taken into analysis.

Cooperative regenerative braking control for front-wheel-drive hybrid electric vehicle based on adaptive regenerative brake torque optimization using under-steer index

In this study, cooperative regenerative braking control of front-wheel-drive hybrid electric vehicle is proposed to recover optimal braking energy while guaranteeing the vehicle lateral stability. In front-wheel-drive hybrid electric vehicle, excessive regenerative braking for recuperation of the maximum braking energy can cause under-steer problem. This is due to the fact that the resultant lateral force on front tire saturates and starts to decrease. Therefore, cost function with constraints is newly defined to determine optimum distribution of brake torques including the regenerative brake torque for improving the braking energy recovery as well as the vehicle lateral stability. This cost function includes trade-off relation of two objectives. The physical meaning of first objective of cost function is to maximize the regenerative brake torque for improving the fuel economy and that of second objective is to increase the mechanical-friction brake torques at rear wheels rather than regenerative brake torque at front wheels for preventing front tire saturation. And weighting factor in cost function is also proposed as a function of under-steer index representing current state of the vehicle lateral motion in order to generalize the constrained optimization problem including both normal and severe cornering situation. For example, as the vehicle approaches its handling limits, adaptation of weighting factor is possible to prioritize front tire saturation over increasing the recuperation of braking energy for driver safety and vehicle lateral stability. Finally, computer simulation of closed loop driver-vehicle system based on Carsim™ performed to verify the effectiveness of adaptation method in proposed controller and the vehicle performance of the proposed controller in comparison with the conventional controller for only considering the vehicle lateral stability. Simulation results indicate that the proposed controller improved the performance of braking energy recovery as well as guaranteed the vehicle lateral stability similar to the conventional controller.

PERFORMANCE AIDING OF MOTORCYCLES USING HYBRID TECHNOLOGY

Rising fuel prices is a major issue faced by the vehicle owners today. Electric vehicles has been introduced in the market but they have not been successful due to various problems like low power output, long charging time, unreliability etc. We hope to solve these problems by the application of hybrid technology. We are designing a hybrid conversion kit which can be implemented on factory made motorcycles for improving their efficiency and performance. Designing a hybrid motorcycle and bringing it into the market can be difficult, but designing a conversion kit, which can be fitted on any motorcycle (old or new), has a higher opportunity in the market. In this kit, we are including a Brushless DC Motor which can be fitted inside the front tyre. We are also designing a user-friendly interface which allows the user to select the modes of operation which are : Engine only, Motor only or both the motor and engine(hybrid). The microcontroller in the kit senses the variables in the system and decides on the mode of running as per the predefined criteria. This kit allows the user to obtain all the characteristics of both the electric motor and the internal-combustion engine. The power output and the efficiency of the vehicle can be considerably increased using this technology.

How driving wheels of front-loaded tractor interact with the terrain depending on tire pressures

This paper analyzes peculiarities of wheel interaction with the terrain for 4WD tractors working with front-mounted loaders. When tractor wheels are loaded by a vertical forces that do not correspond to the specified proportions, deformations of front and rear tires also do not correspond to the specified proportions, and this leads to a kinematic discrepancy because of change in ratio between driving wheels’ rolling radiuses. In case of kinematic discrepancy, wheel slip/skid is taking place. In the paper test results are presented, how driving wheels’ slip/skid of 4WD tractors with front-mounted loaders depend on the vertical loads acting on the wheels and their tire inflation pressures. It was determined that there are dependences on relation between front and rear tire pressures, which allow avoiding wheel slip/skid for the 4WD tractor with front-mounted loader that runs without a load and transports loads. By preparing a tractor for work with front-mounted loader, it is advisable for operator to select a set of tires that would ensure the lead of front wheels lesser compared to the lead that is commonly used for traction works. In this case, the operator creates conditions for wheels’ interaction with the terrain without slip/skid at higher inflation pressures in the front tires.

Vehicle Sideslip Angle EKF Estimator based on Nonlinear Vehicle Dynamics Model and Stochastic Tire Forces Modeling

This paper presents the extended Kalman filter-based sideslip angle estimator design using nonlinear 5DoF single-track vehicle dynamics model with stochastic modeling of tire forces. Lumped front and rear tire forces have been modeled as first order random walk state variables. The proposed estimator is primarily designed for vehicle sideslip angle estimation ; however it can also be used for estimation of tire forces and cornering stiffness. This estimator design does not rely on linearization of the tire force characteristics and it is robust against the variations of tire parameters and does not require the information on coefficient of friction. The estimator performance has been first analyzed by means of computer simulations using the 10DOF two-track vehicle dynamics model and underlying magic formula tire model, and then validated by running the estimator algorithm off-line on the experimental data sets recorded on the test vehicle.

Driver steering model for closed-loop steering function analysis

In this paper, a two level preview driver steering control model for the use in numerical vehicle dynamics simulation is introduced. The proposed model is composed of cascaded control loops: The outer loop is the path following layer based on potential field framework. The inner loop tries to capture the driver's physical behaviour. The proposed driver model allows easy implementation of different driving situations to simulate a wide range of different driver types, moods and vehicle types. The expediency of the proposed driver model is shown with the help of developed driver steering assist (DSA) function integrated with a conventional series production (Electric Power steering System with rack assist servo unit) system. With the help of the DSA assist function, the driver is prevented from over saturating the front tyre forces and loss of stability and controllability during cornering. The simulation results show different driver reactions caused by the change in the parameters or properties of the proposed driver model if the DSA assist function is activated. Thus, the proposed driver model is useful for the advanced driver steering and vehicle stability assist function evaluation in the early stage of vehicle dynamics handling and stability evaluation.

Estimate Lateral Tire Force Based on Yaw Moment without Using Tire Model

This paper demonstrates the implementation of a model-based vehicle estimator, which can be used for lateral tire force estimation without using any highly nonlinear tire-road friction models. The lateral tire force estimation scheme has been designed, and it consists of the following three steps: the yaw moment estimation based on a disturbance observer, the sum of the lateral tire force of two front tires and two rear tires estimation based on a least-square method, and individual lateral tire force estimation based on a heuristic method. The proposed estimator is evaluated under two typical driving conditions and the estimation values are compared with simulator data from CarSim and experimental data provided by GM. Results to date indicate that this is an effective approach, which is considered to be of potential benefit to the automotive industry.

The influence of the tire inflation on pull properties of agriculture tractors

Agricultural tractors are robust and versatile machines, which must comply with the basic requirements of users under various conditions. The main requirements include economical and reliable operation and high performance. Fuel economy could be improved using multiple methods, for example a well trained operator, adequate farming conditions and optimal tire inflation. Tractor tires transmit engine power to the surface and as such they are crucial to tractor operation. In the first part of the field measurement, all tires were inflated to 180kPa, while in the second part of the field measurements the tire pressure was set to 75kPa in front tires and to 65 kPa in rear tires. The results of the field measurement of the John Deere 6920S tractor with different tire inflation shows that pull performance increased by 9.9% and wheel slip decreased by 9.7%.

STUDY ON THE VERTICAL STIFFNESS AND DAMPING COEFFICIENT OF TRACTOR TIRE USING SEMI-EMPIRICAL MODEL

An experiment was conducted to determine the vertical stiffness and damping characteristics of tractor tires for the aim of simulation and design of the tractor suspension system. Three kinds of tractor tires were selected to measure vertical stiffness and damping coefficient by using Free-Vibration Logarithm Decay Method at five levels of tire inflation pressures and two tire loads. The results show that, for all kinds of tire, the stiffness was linearly increased by increasing tire inflation pressure whereas the damping coefficient decreased when tire inflation pressure increased. The stiffness and damping coefficient of tractor tires also depend on the tire size, the structure of tires as front tire or rear tire. Additionally, the damping coefficient shows the increasing trend while the increase in tire stiffness is not clear by increasing tire load. The results also reveal that the appropriate distribution of tire load, tire inflation pressure and tire size can change significantly the tire stiffness and damping coefficient to control tractor vibration. Keywords: Tire stiffness; Damping coefficient; Tractor tire; Tire inflation pressure.

A model and comparison of 4-wheel-drive fixed-chassis tractor rollover during Phase I

A general model to predict quasi-static articulated tractor instability on a slope has been derived using kineto-static modelling. Under simplifying assumptions, it is possible to model fixed-chassis tractors and, in particular, include the effect of front axle-wheel mass. The model is therefore used in this paper to investigate the effect of front body mass on tractor stability and behaviour during Phase I rollover. The results are of particular relevance to four-wheel-drive (4WD) tractors. The change in potential energy for fixed-chassis tractors during Phase I rollover is also evaluated. The effects of mass partitioning are displayed graphically. It is shown that the stability of a tractor depends on the position of the centre of gravity (COG) of the main (posterior) body. For tractors with massive front wheels, tyres and beam axles, this COG is likely not to be the same as that found from the standard COG methods currently adopted. • Parametric model of tractor rollover initiation for tractors with front mass. • Mass partition properties of tractors important for stability calculation. • Model predicts effect of front mass is significant in terms of stability. • Application of brakes to all wheels potentially reduces full rollover likelihood.

DESEMPENHO OPERACIONAL DE UM TRATOR AGRÍCOLA EM FUNÇÃO DA LASTRAGEM, PRESSÃO DE INFLAÇÃO E DESGASTE DO PNEU

Objetivou-se com o presente trabalho avaliar o desempenho operacional de um trator agrícola operando com pneus novos e desgastados em três condições de lastragem e três pressões de inflação dos pneus. O experimento foi realizado na unidade experimental pertencente ao Departamento de Zootecnia da Universidade Federal de Lavras, apresentando teor de água do solo de 25,6% e 14,97 T ha-1 de matéria seca no momento da realização dos testes. Utilizou-se um trator 4x2 TDA, com potência de 65,62 kW (88 HP) no motor. Os pneus foram do tipo R1, com as seguintes características: diagonal (dianteiros: 12.4-24; traseiros: 18.4-30), sendo que, a altura média das garras dos pneus novos foi de 30 e 35 mm para os pneus dianteiros e traseiros respectivamente, enquanto os pneus desgastados as garras mediram 18 mm e 4,5 mm, respectivamente. O delineamento experimental foi de blocos casualizados, em esquema fatorial 2x3x3, com 18 tratamentos e 3 repetições. Os resultados evidenciaram vantagens para o trator quando equipado com pneus novos. A patinagem foi maior quando usado pneus novos devido ao aumento da força e potência na barra de tração.

도로 기하구조에 따른 차량 Microphone 위치별 소음 영향 분석

PURPOSES: The purpose of study is to understand the characteristic of driving noise from the front and rear tire for effective active noise cancellation application. METHODS : As literature review, noise measurement methods were reviewed. Noise measurement conducted at three kind of section by road slope using CPX(Close Proximity Method). Noise data was compared by total sound pressure level and 1/3 octave band frequency sound pressure level. Also, each section was compared by T-test using SPSS. RESULTS : In the case of the uphill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low and high frequency band. In the case of high slope section of Sangsaek-Ri, the sound pressure level of the front tire was higher than that of the rear tire in high frequency. Also, in the case of the downhill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low frequency band. However, the sound pressure levels of both the front and rear tires were approximately the same in the high slope section of Sangsaek-Ri. The result of T-test showed that total sound pressures of the front and rear tires were not different from each other in the case of high slope and high speed. CONCLUSIONS: Road slope was not an important variable for effective active noise cancellation.

Energetic efficiency of an agricultural tractor in function of tire inflation pressure

The tire inflation pressure, among other factors, determines the efficiency in which a tractor can exert traction. It was studied the effect of using two tire inflation pressures, 110.4 kPa in the front and rear wheels, 124.2 kPa in the front wheel and 138 kPa in the rear wheels, the energetic efficiency of an agricultural tractor of 147 kW of engine power, in the displacement speed of 6.0 km.h-1, on track with firm surface, with the tractor engine speed of 2000 rpm. For each condition of the tire pressure, the tested tractor was subjected to constant forces in the drawbar of 45 kN and 50 kN, covering 30 meters. It was used a randomized complete block with a 2x2 factorial arrangement (tire pressure and drawbar power) with four replications, totaling 16 experimental units. Data were subjected to analysis of variance, using the Tukey test at 5% probability for comparison averages. The lowest hourly and specific fuel consumption, the lowest slippage of the wheelsets and the highest efficiency in the drawbar was obtained with the tire inflation pressure of 110.4 kPa in the front and rear tires of the tractor, highlighting that lower pressures improve energetic and operational performance of the tractor.

Fully three-dimensional vehicle dynamics over rough pavement

Simplified vehicle models are usually employed when studying the dynamic effects of road traffic: quarter-car, one-dimensional vertical and two-dimensional longitudinal models are the most common. Furthermore, when complete three-dimensional vehicles are modelled, the differences between the road roughness under the four wheels at each time instant that arise from the time lag between front and rear tyres and from the difference between the profiles under left and right tyres are frequently neglected. The influence of employing simplified models and neglecting those differences has been analysed by means of a three-dimensional truck model. If simple models are utilized or differences between the four wheels are not considered, accelerations in the vehicle body are overestimated, which may lead to an incorrect evaluation of the passengers' comfort. It has also been found that the vertical dynamic load applied by a tyre to the pavement depends not only on the profile under that wheel but also on the profile under the other wheels, mainly under the one on the same axle.

Characterization of non-exhaust coarse and fine particles from on-road driving and laboratory measurements

We investigated the physical and chemical properties of non-exhaust coarse and fine particles generated by on-road driving and in a laboratory setting using a mobile sampling system. The on-road driving and laboratory measurements performed under constant speed driving revealed that particles produced by tire wear had a size distribution in the range of 2–3μm, while roadway particles (RWPs) measured behind the front tire during on-road driving largely comprised crustal materials such as road surface wear particles and road dust as well as tire wear particles (TWPs). The mode diameters of particles obtained from on-road driving under cornering conditions were similar to those obtained under constant speed conditions, but with higher concentrations of crustal elements. Under braking conditions, the particulate matter (PM) concentrations of brake wear particles (BWPs) sampled near the brake pad increased significantly and were much higher than the concentration of RWPs during deceleration, indicating that BWPs are one of the main sources of non-exhaust emissions. In addition, BWPs observed from on-road and laboratory measurements had a broader PM size range (1–10μm) than RWPs. Size-segregated chemical analysis of PM samples indicated that the concentrations of Fe and Ca were highest in the coarse fraction emitted under constant speed and cornering conditions, while Fe, Ba, and Ti were most abundant in the fine fraction emitted during braking events.

Instantaneous Estimation of Road Friction based on Front Tire SAT using Kalman Filter

Instantaneous Estimation of Road Friction based on Front Tire SAT using Kalman Filter

GORDON BELOT. Geometric Possibility. Oxford and New York: Oxford University Press, 2011. ISBN 978-0-19-959532-7. Pp. x + 219

How are we to understand the truth conditions for claims about space-time geometry, e.g., that a cyclist's front tire is trailing the rear tire of another cyclist by 10 cm, or that both cyclists are accelerating as they go downhill? A substantivalist regards the truth or falsity of such claims as underwritten by geometrical relations among the regions of space-time occupied by the tires at different times. Yet do we need to treat these claims as parasitic on structural properties of space-time? A relationalist argues that we only need the geometrical relations among bodies, but then owes us an account of the truth conditions for geometrical claims to replace the substantivalist's. Belot's aim, partially inspired by Leibniz, is to ‘retool the substantivalist truth conditions so that they demand not that certain patterns of geometric relations be (un)instantiated by actual material points, but rather that the instantiation of such patterns be geometrically (im)possible’ (p. 4). The bulk of the book is devoted to a clever and engaging exploration of different ways to flesh out this idea of ‘geometric possibility’, taken as a distinctive kind of modality.

2304 ステアリング捩り剛性が車両の操縦性に及ぼす影響の一考察(OS2-1 交通・物流システムのダイナミクス,OS2 交通・物流システムのダイナミクス,オーガナイズド・セッション(OS))

We focused on the fact that the ease of driving is enhanced by EPS stiffness, theoretically considered the influence by torsional rigidity from a steering angle(steering wheel) to front wheel angle(front tires). As a result, it turned out that a front wheel angle was determined by not only to a steering angle but also the influence of the dynamic state of vehicles, and it was intercepted the influence of the dynamic state of vehicle by making steering torsional rigidity into high torsional rigidity. Next, the simulation was performed about the control performance of vehicle at the time of a disturbance input, and the validity of the theoretical verification was confirmed. Finally, the torsional rigidity range for high torsional rigidity steering utilization was defined.

Design and simulation of the sliding mode controller for the vehicle blow-out process control

During vehicle driving process, the tyre security is very important, but the blow-out is inevitable sometimes, so it is very necessary to control the vehicle stability in order to avoid serious traffic accidents caused by the blowout. In this paper, with the tyre brush model and the seven degree of freedom vehicle model, the vehicle driving system model is modelled, and the front and rear tyres blow-out process was simulated and analysed. The results show that the vehicle will become unstable after the blow-out. In order to ensure the vehicle back to the stable range, the sliding mode controller is designed with the differential braking method, and the yaw rate is controlled by adjusting the braking torque at the opposite side of the blow-out tyre. With simulation, the sliding mode controller can guarantee the vehicle stability, shorten the braking distance and realise the safety brake during the tyre blow-out process.