Tire Test Rig Research Articles

Machine learning-driven intelligent tire wear detection system

Traditional methods detect wear by interpreting mathematical models and tire characteristics; however, these methods struggle to accurately reflect the actual rolling condition of the tire. In this study, we propose a machine learning-based tire wear detection module that can provide accurate results under tire test rig conditions. To develop this module, we designed three key components: integrated acceleration and PVDF sensors within the tire to capture vibration and deformation data; signal preprocessing algorithms to highlight multi-source signal differences under varying wear conditions; and deep learning algorithms to achieve precise tire wear grade identification. Experimental results demonstrate that, under different tire pressures, loads, speeds, and wear levels, the system can accurately identify tire wear grades with 99.99% accuracy by combining data from both sensors.

Tire Performance and Testing under Longitudinal and Combined Slip States: Induced vs Resultant Wheel-Related Slip

ABSTRACT Tires influence many overall vehicle characteristics, including safety, performance, comfort, and handling. Testing is needed to characterize tires for the selection of original equipment manufacturers submissions as well as for the development of other suspension and chassis components. The reality that tire responses are highly nonlinear and change significantly with temperature, wear, and surface pairing makes testing to adequately characterize tires for vehicle development difficult. Furthermore, achieving robust, repeatable braking and driving measurements is particularly challenging. Unlike cornering tests, the test rig input is directly opposed to the tire response vector. Moreover, using an estimated parameter (e.g., slip ratio) as a control value prohibits a clear distinction between the linear test rig input and the nonlinear tire response. In this paper, the influence of the wheel-related slip control on tire performance under longitudinal and combined slip conditions is investigated. Two different tire types are measured in a laboratory environment on an MTS Flat-Trac CT+ tire test rig. A variety of test procedures are used to consider the influence of slip and torque rates under different operating conditions (e.g., wheel loads). A recommendation is given for a low-wear and cost-efficient testing methodology for an improved assessment of tire longitudinal and combined slip characteristics by using a linear test rig input.

Identification of Characteristic Tire Parameters for the Virtual Steering System Design

ABSTRACT The virtual design of steering systems requires suitable premises for predicting realistic steering rack forces. This includes the proper tire used for the parking maneuver. It is important to select the tire from a portfolio that generates the highest rack forces at the vehicle, so that the electro-mechanical dimensioning of the steering system can be safeguarded for all tires of a vehicle. To avoid time-consuming and expensive full vehicle measurements, drilling torques of tires are measured on a Flat-Trac to determine the so-called worst-case tire. However, the determined drilling torques do not correlate with the measured rack forces. This work therefore investigates the suitability of a Kinematics & Compliance test rig converted to a tire test rig. First, it is investigated whether the wheel movements from the parking maneuver can be decomposed into their individual elements on the test bench. In addition, reproducibility studies are carried out and three different methods for determining the aligning torque under camber are presented. Furthermore, measurements for static and dynamic friction values, as well as stiffnesses and the contact patch, are integrated into the new measurement procedure. It becomes apparent that temperature and wear level of the tire play a major role in the reproducibility of the measurements. If the measurement procedure described in this paper is followed exactly, the scatter of the drilling torque can be reduced by up to 24% compared to the old procedure. For the dynamic and the static friction values, the scatter is reduced by about 17% and 22%, respectively. Stiffness scatter can be reduced by up to 16%. With the new measurement procedure, the worst-case tire can be reliably determined. The drilling torques correlate with the rack forces and the additional tire characteristics permit finer resolution. After evaluation and interpretation, recommendations for future developments are discussed.

The testing of pneumatic tyres for the interpretation of tyre behaviour for road/rail vehicles when operating on rails

This paper describes a programme of tyre tests using a purpose built tyre test rig designed specifically to investigate the behaviour of tyres that are used with Road-Rail Vehicles (RRVs). These vehicles are used extensively by the rail industry to support the maintenance of existing rail lines and new construction works. In many cases, using a vehicle that can only operate on the road, or a rail engine that can only operate on tracks will not provide a suitable or effective solution for the task in hand. RRVs are able to operate on both roads and rail, and as such provide a very flexible solution to the rail industry. When operating on the road, RRVs use pneumatic tyres to control their motion and act to all intent and purpose as a normal road vehicle. When operating on rail lines RRVs use a combination of the pneumatic tyres and standard steel rail wheels to control their motion. The rail wheels maintain the directional stability on the track and the pneumatic tyres provide the tractive force to drive and brake the vehicle. Unlike standard road or rail vehicles, there is to date no predictive engineering practice that allows the use of computer simulation to design and optimise the performance of RRVs when they are operating on rails. Computer tools, such as multi-body systems (MBS) analysis are used extensively to design both road and rail vehicles. For road vehicles a tyre model is needed to represent the behaviour in the contact patch between the tyre and the road. For rail vehicles a model is needed to represent the contact force between the train wheel and the track. In both these applications the behaviour is well understood and over the last half century mathematical models have been developed that allow accurate and useful simulation to support the design of new vehicles and trains. In contrast, RRVs have evolved essentially as modifications to standard road vehicles. While the base vehicle may be very well designed to perform on the road, the performance on rail is based on experience and some testing. There is no up-front science involved in designing a RRV to perform effectively during this very important phase of its operation. In order to develop an accurate model to predict RRV performance on rails it is clear that a model of the behaviour of the tyre when in contact with the rail is needed. To date, no such model exists and additionally the testing needed to generate data that could be used to develop a model has never been carried out. The work described here addresses this with the design and build of a unique test rig that can be used to test tyres on rails for a range of operating conditions, and produce a set of initial results that provide a framework for a future tyre/rail model. The paper concludes with a review of the behaviour measured and provides new insights into how well tyres perform on rails and also where the behaviour differs from the well understood behaviour of tyres operating on roads. The important behaviours that would provide the main parameters for a new empirical tyre model are also identified and discussed.

Enhancing Hierarchical Multiscale Off-Road Mobility Model by Neural Network Surrogate Model

Abstract A hierarchical multiscale off-road mobility model is enhanced through the development of an artificial neural network (ANN) surrogate model that captures the complex material behavior of deformable terrain. By exploiting the learning capability of neural networks, the incremental stress and strain relationship of granular terrain is predicted by the ANN representative volume elements (RVE) at various states of the stress and strain. A systematic training procedure for ANN RVEs is developed with a virtual tire test rig model for producing training data from the discrete-element (DE) RVEs without relying on computationally intensive full vehicle simulations on deformable terrain. The ANN surrogate RVEs are then integrated into the hierarchical multiscale computational framework as a lower-scale model with the scalable parallel computing capability, while the macroscale terrain deformation is described by the finite element (FE) approach. It is demonstrated with several numerical examples that off-road vehicle mobility performances predicted by the proposed FE-ANN multiscale terrain model are in good agreement with those of the FE-DE multiscale model while achieving a substantial computational time reduction. The accuracy and robustness of the ANN RVE for fine-grain sand terrain are discussed for scenarios not considered in training datasets. Furthermore, a drawbar pull test simulation is presented with the ANN RVE developed with data in the cornering scenario and validated against the full-scale vehicle test data. The numerical results confirm the predictive ability of the FE-ANN multiscale terrain model for off-road mobility simulations.

Full-field strain measurements of the inside of an agricultural tyre using digital image correlation

This paper investigates strain measured on the inside of an agricultural tyre with large tread-blocks during a series of static tests using a novel measuring system. The full field strain measurements may be used in the development of a tyre which is capable of estimating tyre forces from strain measurements. The strain measurement system makes use of a calibrated stereo camera system on a mechanical stabilizing system that keeps the cameras pointed at the inside surface of the tyre in contact with the road while the wheel rotates. A static tyre test rig is used to displace the road surface relative to the tyre in the vertical and longitudinal direction. The large tread-blocks caused strain concentrations on the inner surface as the tyre deforms to comply with the road surface. Vertical and longitudinal tests each produce unique strain patterns in the contact patch region. Relationships between the applied forces and strain measurements were developed and showed that these relationships are near linear with R2 values above 0.97. The strain measurements also show that the location where strain gauges, for single point strain measurements, are placed inside the tyre is very important on large lugged tyres.

Influence of camber angle on tire tread behavior by an on-board strain-based system for intelligent tires

Tires are a key sub-system of vehicles that have a big responsibility in comfort, fuel consumption and traffic safety. Nevertheless, current tires are just passive rubber elements which do not contribute actively to improve the driving experience or the vehicle safety. The lack of information that tires provide during driving is the main reason to develop an intelligent tire, which could provide useful information to other systems and become an active safety system. In this paper, an experimental tire strain-based system is used to measure tire tread deformation by means of strain gauges. Tests under different working conditions such as vertical load or slip angle considering a certain camber angle have been carried out using an indoor tire test rig. The results prove that the camber angle has a significant effect on strain signal, so it should be considered for tire working conditions estimation purposes.

Prediction of Close-Proximity Tire-Road Noise from Tire Cavity Noise measurements using a statistical approach

Noise due to the contact between the tire and the road is taking more and more importance in the development of cars, tires, and road coverings. This noise influences the comfort perception of the driver and the living quality of the surrounding people and has to be taken into account during the tire development. A recent study from the Danish Ministry of Infrastructure and Environment estimated that a reduction of the Tire-Road Noise of 6 dB(A) between 2009 and 2020 could save 11 billion euros yearly by reducing the number of annoyed peopled by 13 million and the number of sleep disturbed people by 6 million.Nowadays, several methods are used to quantify the noise of a rolling tire. All of them are, however, cost- and time-expensive, lack mobility, and are dependent on the surrounding weather and operating conditions. With a self-developed measurement system, it is now possible to predict the emitted Tire-Road Noise by measuring the noise inside the tire cavity.In this study, reproducible measurements were realized on a tire test bench, where the Tire Cavity Noise and the exterior Tire-Road Noise were simultaneously recorded. The influence of many parameters, such as the driving speed, tire load, inflation pressure, and tire cavity air temperature, on the cavity noise were studied. In the end, a correlation between the Tire Cavity Noise and the exterior Tire-Road Noise was found with a prediction quality of 1.4 dB(A).This study is a first step towards reducing the time and the costs needed for standard acoustic measurements for tire homologation or for assessing the acoustic quality of different road surfaces. Our measurement method is namely not influenced by the surrounding buildings and can be used without any interference in the flowing traffic. The costs for the needed hardware are also negligible compared to the conventional exterior noise measurement systems. However, the transferability of the results on the tire test rig to field measurements still has to be checked and will be done in a future study.

Sophisticated but quite simple contact calculation for handling tire models

Handling tire models like Pacejka (Tire and Vehicle Dynamics, 3rd edn., Elsevier, Amsterdam, 2012) or TMeasy (Rill in Proc. of the XV Int. Symp. on Dynamic Problems of Mechanics, Buzios, RJ, Brazil, 2013) consider the contact patch as one coherent plane. As a consequence, the irregularities of a rough road profile must be approximated by an appropriate local road plane that serves as an effective road plane in order to calculate the geometric contact point and the corresponding contact velocities. The Pacejka/SWIFT tire model employs a road enveloping model that generates the effective height and slope by elliptical cams. TMeasy just uses four representative road points for that purpose. In addition, TMeasy replaces the geometric contact point by the static contact point and shifts it finally to the dynamic contact point that represents the point where the contact forces are applied. In doing so, a rather sophisticated but still simple contact calculation is possible. Simulations obtained with a virtual tire test rig and fully nonlinear three-dimensional multibody system models of a motor-scooter and a passenger car demonstrate the potential of this contact approach.

Modeling of Contact Patch in Dual-Chamber Pneumatic Tires

ABSTRACT This study presents an investigation of the inner tire surface strain measurement by using piezoelectric polymer transducers adhered on the inner liner of the tire, acting as strain sensors in both conventional and dual-chamber tires. The piezoelectric elements generate electrical charges when strain is applied. The inner liner tire strain can be found from the generated charge. A wireless data logger was employed to measure and transmit the measured signals from the piezoelectric elements to a PC to store and display the readout signals in real time. The strain data can be used as a monitoring system to recognize tire-loading conditions (e.g., traction, braking, and cornering) in smart tire technology. Finite element simulations, using ABAQUS, were employed to estimate tire deformation patterns in both conventional and dual-chamber tires for pure rolling and steady-state cornering conditions for different inflation pressures to simulate on-road and off-road riding tire performances and to compare with the experimental results obtained from both the piezoelectric transducers and tire test rig.

A Strain-Based Method to Detect Tires' Loss of Grip and Estimate Lateral Friction Coefficient from Experimental Data by Fuzzy Logic for Intelligent Tire Development.

Tires are a key sub-system of vehicles that have a big responsibility for comfort, fuel consumption and traffic safety. However, current tires are just passive rubber elements which do not contribute actively to improve the driving experience or vehicle safety. The lack of information from the tire during driving gives cause for developing an intelligent tire. Therefore, the aim of the intelligent tire is to monitor tire working conditions in real-time, providing useful information to other systems and becoming an active system. In this paper, tire tread deformation is measured to provide a strong experimental base with different experiments and test results by means of a tire fitted with sensors. Tests under different working conditions such as vertical load or slip angle have been carried out with an indoor tire test rig. The experimental data analysis shows the strong relation that exists between lateral force and the maximum tensile and compressive strain peaks when the tire is not working at the limit of grip. In the last section, an estimation system from experimental data has been developed and implemented in Simulink to show the potential of strain sensors for developing intelligent tire systems, obtaining as major results a signal to detect tire’s loss of grip and estimations of the lateral friction coefficient.

A Strain-Based Method to Estimate Slip Angle and Tire Working Conditions for Intelligent Tires Using Fuzzy Logic.

Tires equipped with sensors, the so-called “intelligent tires”, can provide vital information for control systems, drivers and external users. In this research, tire dynamic strain characteristics in cornering conditions are collected and analysed in relation to the variation of tire working conditions, such as inflation pressure, rolling speed, vertical load and slip angle. An experimental tire strain-based prototype and an indoor tire test rig are used to demonstrate the suitability of strain sensors to establish relations between strain data and lateral force. The results of experiments show that strain values drop sharply when lateral force is decreasing, which can be used to predict tire slip conditions. As a first approach to estimate some tire working conditions, such as the slip angle and vertical load, a fuzzy logic method has been developed. The simulation and test results confirm the feasibility of strain sensors and the proposed computational model to solve the non-linearity characteristics of the tires’ parameters and turn tires into a source of useful information.

Tyre model development using co-simulation technique for helicopter ground operation

This paper describes the development of a new aircraft tyre model applied using a co-simulation approach for the multibody dynamic simulation of helicopter ground vehicle dynamics. The new tyre model is presented using a point follower approach that makes a novel contribution to this area by uniquely combining elements of two existing tyre models used by the aircraft industry, namely the NASA R64 model developed by Smiley and Horne and the Engineering Sciences Data Unit (ESDU) Mitchell tyre model. Before the tyre model was used with a full helicopter model, a virtual tyre test rig was used to examine the tyre and to predict the tyre forces and moments for a range of tyre states. The paper concludes by describing the successful application of the new tyre model with a full helicopter model and the simulation of representative landing, take-off and runway taxiing manoeuvres. The predictive capability of the model is demonstrated to show the open-loop ground vehicle dynamics response of the helicopter and also the ground load predictive capability for the distribution of loads through the tyres, wheels and landing gears.

Discrete mass tyre model for ride investigation over uneven rigid terrain

The goal of this study is to develop a tyre model able to capture the vertical tyre dynamic behaviour while traversing over an uneven rigid surface. The proposed tyre model takes advantage of modelling the wheel-tyre assembly as a multi body dynamic system in order to investigate the tyre ride behaviour over such terrain. Several experiments are conducted for the tyre model parameter identification and the tyre model validation with an indoor quarter car tyre test rig and an outdoor portable tyre trailer test rig. The selected scenarios are simulated by using the discrete mass tyre model with the tyre parameters obtained from the experiments. The simulation results of the selected scenarios are presented and compared with the experimental data.

Kinematic Analysis of Tire Test Rig for Mechanical Properties

The test rig of the A-frame which is used more at home and abroad is carried out kinematic analysis. The offsets of slip angle,camber angle and the tire trace center are discovered when the test rig is in the composite posture of slip angle and camber angle. The offset formula is deduced by the method of space analytic geometry based on the tire coordinate system defined in ISO.The results showed that each offset can't be ignored in a large complex attitude angle. In order to effectively solve the phenomenon,a novel structure of six degrees of freedom(DOF) tire test rig is proposed. The length of six electric cylinders is calculated when the new test rig is in different postures by the Euler angles of rotation method. The control precision of attitude angle of the tire is analyzed and six DOF platform electric cylinders are space rearranged. The results showed that each physical quantity is with no offset when the new structure six DOF tire test rig is in the composite posture and the tire posture can be arbitrarily controlled. As the same time,a new program of six power cylinder arrangement improves the control precision of tire attitude angle.

Robust piezoelectric composites for energy harvesting in high-strain environments

High-strain environments, such as are found in automobile tires, provide deformation energy that can be harvested using piezoelectric materials, for instance, for powering electronics such as wireless sensors. Despite numerous efforts, none of the present devices easily satisfy the stringent operating and lifetime requirements for use inside a car tire, such as mechanical (accelerations of up to 3000 m/s2) and thermal requirements (temperatures of −40°C to 120°C), often leading to complex and costly solutions. Polymer–piezoelectric ceramic composite properties can be designed to fulfill the operating requirements. Furthermore, these materials are suitable for low-cost mass production and easy integration in the tire itself. Composite materials with increased output can be manufactured using the dielectrophoretic processing technique, which causes the alignment of the piezoelectric particles inside the polymer matrix, to obtain materials with adequate flexibility combined with a high energy density. In this study, we present the design, synthesis, and integration of novel composite material foils in automobile tires. The advantage of these dielectrophoretically structured composite materials is demonstrated and their output is compared to conventional piezoelectric composites. Furthermore, the charge signal output of a number of foil-based prototypes tested using an automobile tire test rig is evaluated and discussed with respect to energy harvesting performance.

Estimation of Tire-Road Friction Coefficient Using a Novel Wireless Piezoelectric Tire Sensor

A tire-road friction coefficient estimation approach is proposed which makes use of the uncoupled lateral deflection profile of the tire carcass measured from inside the tire through the entire contact patch. The unique design of the developed wireless piezoelectric sensor enables the decoupling of the lateral carcass deformations from the radial and tangential deformations. The estimation of the tire-road friction coefficient depends on the estimation of slip angle, lateral tire force, aligning moment, and the use of a brush model. The tire slip angle is estimated as the slope of the lateral deflection curve at the leading edge of the contact patch. The portion of the deflection profile measured in the contact patch is assumed to be a superposition of three types of lateral carcass deformations, namely, shift, yaw, and bend. The force and moment acting on the tire are obtained by using the coefficients of a parabolic function which approximates the deflection profile inside the contact patch and whose terms represent each type of deformation. The estimated force, moment, and slip angle variables are then plugged into the brush model to estimate the tire-road friction coefficient. A specially constructed tire test rig is used to experimentally evaluate the performance of the developed estimation approach and the tire sensor. Experimental results show that the developed sensor can provide good estimation of both slip angle and tire-road friction coefficient.

A novel wireless piezoelectric tire sensor for the estimation of slip angle

This paper introduces a simple approach for the analysis of tire deformation and proposes a new piezoelectric tire sensor for physically meaningful measurements of tire deformations. Tire deformation measurements in the contact patch can be used for the estimation of slip angle, tire forces, slip ratio and tire–road friction coefficient. The specific case of a wireless tire deformation sensor for the estimation of slip angle is taken up in this paper. A sensor in which lateral sidewall deformation can be decoupled from radial deformation is designed. The slope of the lateral deflection curve in the contact patch is used to calculate slip angle. A specially constructed tire test rig is used to experimentally evaluate the performance of the developed sensor. Results show that the developed sensor can accurately estimate slip angles up to values of 5°.

On-board estimation of dynamic tyre forces from optically measured tyre carcass deflections

Active safety systems would benefit from accurate information on tyre forces. A special sensor module has been developed for research purposes to study real-time tyre force estimation from tyre carcass displacements. The forces can be measured in vertical, lateral and longitudinal directions. The sensor measures tyre carcass movement with respect to the rim and transmits the data wirelessly to the chassis. The raw data is analysed and tyre force information is available on a CAN-bus. The sensor is calibrated in a tyre test rig and proving ground measurement results are presented. The lateral and longitudinal force estimates are accurate when compared with the vehicle accelerations, but the vertical force is difficult to estimate during heavy braking manoeuvres.

Parameter identification for LMS CDTire

This paper discusses the parameter identification procedure for the LMS comfort and durability tyre (LMS CDTire) model. CDTire is a family of three models (namely CDTire 20, CDTire 30 and CDTire 40) based on a macroscopic physical description of tyres, which is a compromise between scope of applicability and speed. The ‘macroscopic description’ implies that the actual model contains elements representing, for example, the ‘belt’, but not individual cords of the belt layers. Therefore, model parameters such as the belt bending stiffness essentially have to be determined by testing the whole tyre in a number of different ways instead of assembling mechanical properties of all the individual elements of a tyre such as cord stiffness. The considered tests are standard tyre tests that can be performed by most tyre test facilities. The parameter identification process is explained in a generic way with exemplary focus on one specific identification subtask, as the complete process description would go beyond the scope of this article. Furthermore, some of the strategic decisions made in the build-up of the parameter identification process are highlighted. Together with a more involved discussion on some numerical aspects of the tyre test rig simulations, the choice of optimization algorithms is explained. The technical discussion is complemented with some results obtained with this parameter identification procedure on a 205/55 R16 non-commercial passenger car tyre.