To simulate a six wheeled vehicle at the handling limit, a vehicle model with a brush tyre model is used in order to get physicallyreasonable simulation results during high combined slip conditions. Different vehicle configurations are considered, where frontwheel steering is combined with either second axle steering, rear wheel steering or individual wheel torque control. By applyingdifferent vehicle slip angles and thereby limiting the DOF of the vehicle model, the vehicle configurations are evaluated duringdifferent driving conditions similar to for example front wheel skidding and rear wheel skidding. The results show that by applyingindividual torque control to the front wheel steered vehicle, the performance is improved for all evaluated manoeuvres, and it is theonly method among the evaluated methods that significantly increases the achievable aligning torque during a rear wheel skid if thevehicle slip angle is larger than the maximum front wheel steering angle. Rear wheel steering, on the other hand, has negligibleeffect on the aligning torque during a rear wheel skid for the six-wheeler.
A method to measure terrain parameters and drawbar pull for a six-wheeled vehicle on sand is proposed,tested and evaluated. The method is developed in order to be able to validate previously proposedtire/terrain models that are developed to simulate the behaviour of a six-wheeled vehicle withelectric transmission on soft ground. Tests were performed at different tire pressures, and it is shownthat the drawbar pull is vastly improved at lower tire pressure. Since the tire/terrain model uses terrainparameters such as pressure–sinkage and shear stress–displacement relationships, the sand propertiesare measured with a Bevameter. Parameters in the pressure–sinkage relationship are estimated to fitthe measured data. Both external and internal shearing properties of the sand are measured using arubber coated shear ring and a shear ring with grousers, respectively. The measured shear behaviouris shown to agree reasonably well with shear curves of simple exponential form. This will be a basein the development of a strategy to get improved cross country characteristics of six-wheeled vehicleswith individually controlled electric transmission on soft ground.
A known problem of articulated vehicles is that snaking oscillations may occur at high speed. For ride comfort reasons, it is desirable to introduce suspended axles on articulated vehicles such as wheel loaders which are traditionally built without wheel suspension. This paper investigates how this may affect the snaking stability, by studying the vehicle dynamic behaviour of a multibody simulation model with and without suspension. Results show that an axle suspension may have a slightly destabilising effect, although the difference is small and can be offset by a stiffer or more damped steering system.
This paper describes the development and evaluation of an articulated frame steer testvehicle on a model-scale. Vehicles with articulated steering are known to exhibit unstable behaviour in the form of snaking or folding instabilities when operated at high speed, as previously studied using analytical models, simulations and full vehicle tests. The aim ofthis study is to design a scaled test vehicle that is able to reproduce unstable modes found in articulated vehicles. The model vehicle may provide greater insight than simulations, while avoiding the costs and hazards associated with full vehicle tests. The objective is also to investigate how well a linearised planar model and eigenvalue analysis can predict vehicle stability properties. Experimental and theoretical results have been critically analysed, and found to exhibit typical full vehicle behaviour. The linear mathematical model exhibited similar trends when compared to the scale model test results.
To build on existing research excellence and strength, KTH has defined five distinct research focus areas: Transport, Energy, Materials, Information and Communication Technology, and Medical and Biomedical Technology. Here, the KTH Transport Platform sets the scene for KTH’s present and future role in society within the transport area. A starting point is that KTH today possesses both broad and in-depth expertise within several key areas of transport research. The problems and challenges confronting future transport are however so complex that no player is able to solve them alone. Therefore, it is necessary to employ a multidisciplinary and a multi-stakeholder approach. On this background the aim is to establish a joint passion and a unique mechanism for holistic transport research, demonstration and innovation together with partners in research community, industry and public bodies. The five thematic research areas within the KTH Transport Platform are: The Holistic Transport System Approach,The Future Transportation Infrastructure,Innovative Vehicle Concepts, Transport in the Information Era and Policy and Institutional Frameworks. The mission of the KTH Transport Platform is to be an effective and efficient vehicle for delivering multidisciplinary research aiming for transport solutions servicing the society of tomorrow. The expected outcome is an increased success in large, complex research applications due to good knowledge about societal and industrial needs with a focus on innovation. To conclude, there is a need for an initiative with passion for joint transport innovation. Here the word “joint” stands for both multi-disciplinary and multi-stakeholder approaches, with all parties involved committed to these.
This paper presents state-of-the art within advanced vehicle dynamics of heavy trucks with the perspective of road safety. The most common accidents with heavy trucks involved are truck against passenger cars. Safety critical situations are for example loss of control (such as rollover and lateral stability) and a majority of these occur during speed when cornering. Other critical situations are avoidance manoeuvre and road edge recovery. The dynamic behaviour of heavy trucks have significant differences compared to passenger cars and as a consequence, successful application of vehicle dynamic functions for enhanced safety of trucks might differ from the functions in passenger cars. Here, the differences between vehicle dynamics of heavy trucks and passenger cars are clarified. Advanced vehicle dynamics solutions with the perspective of road safety of trucks are presented, beginning with the topic vehicle stability, followed by the steering system, the braking system and driver assistance systems that differ in some way from that of passenger cars as well.
A direct yaw moment control (DYC) for energy-efficiency and a DYC for stability of electric vehicles (EVs) are proposed. The DYC for energy-efficiency is active during non-safety-critical cornering manoeuvres to improve the energy-efficiency of EVs. The DYC for stability is active during safety-critical manoeuvres to keep the vehicle stable. A combination of the DYC for energy-efficiency and the DYC for stability is studied. A stability judgement based on the yaw rate and slip angle is designed for evaluating the criticality of the vehicle's working state. A switching principle for alternating between the DYC for energy-efficiency and the DYC for stability is designed. During non-safety-critical cornering manoeuvres, it is shown that the DYC for energy efficiency can save considerable percentage of energy compared to both equal torque driving and the DYC for stability. During cornering manoeuvres containing both non-safety-critical parts and safety-critical parts, the simulation results in this work show that the combination of the DYC for energy-efficiency and the DYC for stability can give 12% to 18% energy savings compared to the DYC for stability only for the vehicle and manoeuvres studied.
An active energy-efficient direct yaw moment control (DYC) for in-wheel motor electric vehicles taking motor efficiency maps into consideration is proposed in this paper. The potential contribution of DYC to energy saving during quasi-steady-state cornering is analysed. The study in this paper has produced promising results which show that DYC can be used to reduce the power consumption while satisfying the same cornering demand. A controller structure that includes a driver model and an offline torque distribution law during continuous driving and cornering is developed. For comparison, the power consumption of stability DYC is also analysed. Simulations for double lane change manoeuvres are performed and driving conditions either with a constant velocity or with longitudinal acceleration are designed to verify the effectiveness of the proposed controller in different driving situations. Under constant velocity cornering, since the total torque demand is not high, two rear wheels are engaged and during cornering it is beneficial to distribute more torque to one wheel to improve energy efficiency. In the simulated driving manoeuvres, up to 10% energy can be saved compared to other control methods. During acceleration in cornering, since the total torque demand is high, it is energy-efficient to use all the four in-wheel motors during cornering.
An active energy-efficient direct yaw moment control (DYC) for in-wheel motor electricvehicles taking motor efficiency maps into consideration is proposed in this paper. The potentialcontribution of DYC to energy saving during quasi-steady-state cornering is analysed. The study inthis paper has produced promising results which show that DYC can be used to reduce the powerconsumption while satisfying the same cornering demand. A controller structure that includes adriver model and an offline torque distribution law during continuous driving and cornering isdeveloped. For comparison, the power consumption of stability DYC is also analysed. Simulations fordouble lane change manoeuvres are performed and driving conditions either with a constant velocityor with longitudinal acceleration are designed to verify the effectiveness of the proposed controller indifferent driving situations. Under constant velocity cornering, since the total torque demand is nothigh, two rear wheels are engaged and during cornering it is beneficial to distribute more torque toone wheel to improve energy efficiency. In the simulated driving manoeuvres, up to 10% energy canbe saved compared to other control methods. During acceleration in cornering, since the total torquedemand is high, it is energy-efficient to use all the four in-wheel motors during cornering.
For sustainability reasons it is important to reduce energy consumption during driving. One contribution to energy savings is by using proper wheel torque distributions during manoeuvring. An active energy-efficient direct yaw moment control (DYC) for electric vehicles has previously been proposed by the authors, taking the motor efficiency map into consideration. The results show a potential for reduced energy losses during driving, but it might result in stability problems during safety-critical maneuvres. In this work, consequences on stability due to this proposed energy efficient DYC is explored. Also an approach combining DYC both energy-efficiency and stability is proposed. The simulation results show that for the studied case the combination of DYC for energy-efficiency and stability can have an potential to both keep the vehicle safe and save considerable percentage of energy during both non safety-critical and safety-critical driving manoeuvres.
For sustainability reasons it is important to reduce energyconsumption during driving. One contributionto energysavings is by AQ1using proper wheel torque distributions during manoeuvring. An activeenergy-efficient direct yaw moment control (DYC) for electric vehicleshas previously been proposed by the authors, taking the motor efficiencymap into consideration. The results show a potential for reduced energylosses during driving, but it might result in stabilityproblems duringsafety-critical maneuvres. In this work, consequences on stability dueto this proposed energy efficient DYC is explored. Also an approachcombining DYC both energy-efficiency and stability is proposed. Thesimulation results show that for the studied case the combination ofDYC for energy-efficiency and stability can have an potential to bothkeep the vehicle safe and save considerable percentage of energy duringboth non safety-critical and safety-critical driving manoeuvres.
This paper focuses on the use of camber control and torque vectoring in order to make future vehicles more energy efficient and thereby more environmentally friendly. The energy loss during steady state cornering including rolling resistance loss, aerodynamic loss, longitudinal slip loss and lateral slip loss, is formulated and studied. Camber control, torque vectoring control and a combination of both are compared. From the simulation results, it can be concluded that during steady state cornering, torque vectoring has a very small contribution to energy reduction while camber control can make a significant contribution to energy saving. By combining torque vectoring and camber control during steady state cornering, in theory up to 14% energy saving are found for certain cases.
Actively controlling the camber angle to improve energy efficiency has recently gained interest due to the importance of reducing energy consumption and the driveline electrification trend that makes cost-efficient implementation of actuators possible. To analyse how much energy that can be saved with camber control, the effect of changing the camber angles on the forces and moments of the tyre under different driving conditions should be considered. In this paper, Magic Formula tyre models for combined slip and camber are used for simulation of energy analysis. The components of power loss during cornering are formulated and used to explain the influence that camber angles have on the power loss. For the studied driving paths and the assumed driver model, the simulation results show that active camber control can have considerable influence on power loss during cornering. Different combinations of camber angles are simulated, and a camber control algorithm is proposed and verified in simulation. The results show that the camber controller has very promising application prospects for energy-efficient cornering.
This paper presents results on how to optimally negotiate two safety-critical vehicle maneuvers, depending on different set of actuators. The motives for this research has been to provide viable knowledge of limitations of vehicle control under the presence of preview sensors, such as radar, camera and navigation. Using tools available in the JModelica.org platform, an optimal path is found by optimising the sequence of actuator requests during the maneuver. Particular interest is paid on the optimal trade-off between braking and steering.
A failure-sensitive driver model has been developed in the research study presented in this paper. The model is based on measurements of human responses to dierent failure conditions inuencing the vehicle directional stability in a moving-base driving simulator. The measurements were made in a previous experimental study where test subjects were exposed to three sudden failure conditions that required adequate corrective measures to maintain the vehicle control and regain the planned trajectory. A common driver model and a failure-sensitive driver model have been compared, and results for the latter agree well with the measured data. The proposed failure-sensitive driver model is capable of maintaining the vehicle control and regaining the planned trajectory similarly to the way in which humans achieved this during a wheel hub motor failure in one of the rear wheels.
In this work, a fault-tolerant control strategy for an electric vehicle is developed and analysed for a wheel hub motor failure during a straight line driving manoeuvre. Based on the control allocation principle, an analytical approach is compared to an optimisation approach and both are investigated for their suitability to handle such failures. The analytical control allocation strategy has shown promising results similar to the optimal control allocation strategy. The improvements in vehicle stability and maintained desired path are also verified by experiments. The analytical approach is implemented in an experimental vehicle verifying the simulation results without driver in the loop. An experimental study including drivers is further conducted to analyse the influence of the control allocation strategy on the driver-vehicle interaction for the same manoeuvre. Further improvements for vehicle stability and lateral deviation are found for the driver study when an analytical control allocation strategy is included. The driver-vehicle interaction to a fault is improved strongly due to controller intervention. This fault-tolerant control strategy has shown promising results and its potential to improve traffic safety.
A fault classification method is proposed which has been applied to an electric vehicle. Potential faults in the different subsystems that can affect the vehicle directional stability were collected in a failure mode and effect analysis. Similar driveline faults were grouped together if they resembled each other with respect to their influence on the vehicle dynamic behaviour. The faults were physically modelled in a simulation environment before they were induced in a detailed vehicle model under normal driving conditions. A special focus was placed on faults in the driveline of electric vehicles employing in-wheel motors of the permanent magnet type. Several failures caused by mechanical and other faults were analysed as well. The fault classification method consists of a controllability ranking developed according to the functional safety standard ISO 26262. The controllability of a fault was determined with three parameters covering the influence of the longitudinal, lateral and yaw motion of the vehicle. The simulation results were analysed and the faults were classified according to their controllability using the proposed method. It was shown that the controllability decreased specifically with increasing lateral acceleration and increasing speed. The results for the electric driveline faults show that this trend cannot be generalised for all the faults, as the controllability deteriorated for some faults during manoeuvres with low lateral acceleration and low speed. The proposed method is generic and can be applied to various other types of road vehicles and faults.
Electric powertrain faults that could occur during normal driving can affect the dynamic behaviour of the vehicle and might result in significant course deviations. The severity depends both on the characteristics of the fault itself as well as on how sensitive the vehicle reacts to this type of fault. In this work, a sensitivity study is conducted on the effects of vehicle design parameters, such as geometries and tyre characteristics, and fault characteristics. The vehicle specifications are based on three different parameter sets representing a small city car, a medium-sized sedan and a large passenger car. The evaluation criteria cover the main motions of the vehicle, i.e. longitudinal velocity difference, lateral offset and side slip angle on the rear axle as indicator of the directional stability. A design of experiments approach is applied and the influence on the course deviation is analysed for each studied parameter separately and for all first order combinations. Vehicle parameters of high sensitivity have been found for each criterion. The mass factor is highly relevant for all three motions, while the additional factors wheel base, track width, yaw inertia and vehicle velocity are mainly influencing the lateral and the yaw motion. Changes in the tyre parameters are in general less significant than the vehicle parameters. Among the tyre parameters, the stiffness factor of the tyres on the rear axle has the major influence resulting in a reduction of the course deviation for a stiffer tyre. The fault amplitude is an important fault parameter, together with the fault starting gradient and number of wheels with fault. In this study, it was found that a larger vehicle representing a SUV is more sensitive to these types of faults. To conclude, the result of an electric powertrain fault can cause significant course deviations for all three vehicle types studied.
This paper presents a fault handling strategy for electric vehicles with in-wheel motors. The ap-plied control algorithm is based on tyre-force allocation. One complex tyre-force allocation meth-od, which requires non-linear optimization, as well as a simpler tyre force allocation method are developed and applied. A comparison between them is conducted and evaluated against a standard reference vehicle with an Electronic Stability Control (ESC) algorithm. The faults in consideration are electrical faults that can arise in in-wheel motors of permanent-magnet type. The results show for both tyre-force allocation methods an improved re-allocation after a severe fault and thus re-sults in an improved state trajectory recovery. Thereby the proposed fault handling strategy be-comes an important component to improve system dependability and secure vehicle safety.
This research work studies the impact of single wheel hub motor failures on the dynamic behaviour of electric vehicles and the corresponding driver reactions. An experimental study in a moving-base driving simulator is conducted to analyse the influence of single wheel hub motor failures for motorway speeds. Driver reaction times are derived from the measured data and discussed in their experimental context. The failure is rated objectively on the dynamic behaviour of the vehicle and compared to the subjective evaluation. Findings indicate that critical traffic situations impairing traffic safety can occur for motorway speeds. Clear counteractions by the drivers had to be taken.
This research work studies the impact of single wheel hub motor failures on the dynamic behaviour of electric vehicles and the corresponding driver reactions. An experimental study in a moving-base driving simulator is conducted to analyse the inuence of single wheel hub motor failures for motorway speeds. Driver reaction times are derived from the measured data and discussed in their experimental context. The failure is rated objectively on the dynamic behaviour of the vehicle and compared to the subjective evaluation. Findings indicate that critical trac situations impairing trac safety can occur for motorway speeds. Clear counteractions by the drivers had to be taken.
An experimental field study investigating the impact of single wheel hub motor failures on the dynamic behavior of a vehicle and the corresponding driver reaction is presented in this work. The experiment is performed at urban speeds on a closed off test track. The single wheel hub motor failure is emulated with an auxiliary brake system in a modified electric vehicle. Driver reaction times are derived from the measured data and discussed in their experimental context. The failure is rated and evaluated objectively based on the dynamic behavior of the vehicle. Findings indicate that driver reactions are more apparent for the accelerator pedal compared to the steering wheel response. The controllability evaluation of the vehicle behavior shows that no critical traffic situation occurs for the tested failure conditions. However, even small deviations of the vehicle can impair traffic safety, specifically for other traffic participants like bicyclist and pedestrians.
Fault-tolerant vehicle design is an emerging inter-disciplinary research domain, which is of increasedimportance due to the electrification of automotive systems. The goal of fault-tolerant systems is to handleoccuring faults under operational condition and enable the driver to get to a safe stop. This paperpresents results from an extended survey on fault-tolerant vehicle design. It aims to provide a holisticview on the fault-tolerant aspects of a vehicular system. An overview of fault-tolerant systems in generaland their design premises is given as well as the specific aspects related to automotive applications. Thepaper highlights recent and prospective development of vehicle motion control with integrated chassiscontrol and passive and active fault-tolerant control. Also, fault detection and diagnosis methods arebriefly described. The shift on control level of vehicles will be accompanied by basic structural changeswithin the network architecture. Control architecture as well as communication protocols and topologiesare adapted to comply with the electrified automotive systems. Finally, the role of regulations andinternational standardization to enable fault-tolerant vehicle design is taken into consideration.
Fault-tolerant vehicle design is an emerging inter-disciplinary research domain, which is of increased importance due to the electrification of automotive systems. The goal of fault-tolerant systems is to handle occuring faults under operational condition and enable the driver to get to a safe stop. This paper presents results from an extended survey on fault-tolerant vehicle design. It aims to provide a holistic view on the fault-tolerant aspects of a vehicular system. An overview of fault-tolerant systems in general and their design premises is given as well as the specific aspects related to automotive applications. The paper highlights recent and prospective development of vehicle motion control with integrated chassis control and passive and active fault-tolerant control. Also, fault detection and diagnosis methods are briefly described. The shift on control level of vehicles will be accompanied by basic structural changes within the network architecture. Control architecture as well as communication protocols and topologies are adapted to comply with the electrified automotive systems. Finally, the role of regulations and international standardization to enable fault-tolerant vehicle design is taken into consideration.
Three fault-tolerant control strategies for electric vehicles with wheel hub motors are presented and compared, which are all based on the control allocation principle. The main objective is to maintain the directional stability of the vehicle in case of a component failure during high speed manoeuvres. Two simplified strategies that are suited for on-board implementation are derived and compared to an optimal control allocation strategy and a reference vehicle with a basic electronic stability control system. The occurring faults are considered to be in the electric high-voltage system that can arise in wheel hub motors. All three control allocation strategies show improved re-allocation of traction forces after a severe fault, and hence an improved directional stability. However, the performance of both simplified algorithms shows limitations in case of force demands outside the capabilities of the respective actuator. This work shows that vehicle safety is increased by the proposed fault-tolerant control strategies.
Ground vehicles are sensitive to crosswinds, affecting aerodynamic and handling performance, and in some cases safety. Therefore it is important to be able to predict vehicle performance when exposed to crosswinds. The aim of the work presented in this paper is to assess the order of the model complexity in order to capture the vehicle behaviour during a transient crosswind event, regarding the interaction of the aerodynamic forces and the vehicle dynamic response. That is, the necessity to perform a full dynamic coupling instead of a static coupling to capture the vehicle performance both with respect to aerodynamics and the vehicle dynamics as is done today. The model used in the computations is based on the Ground Transportation System (GTS) model, which is simulated to run on a road passing a crosswind passage. The aerodynamic computations are performed using Detached Eddy Simulation (DES) coupled to a bicycle model for the vehicle dynamics. Here, two degrees of freedom are considered, that is, lateral translation and yaw motion. The change of the vehicle position in the aerodynamic domain is enabled through the use of the overset mesh technique. The results show that the full dynamic coupling is needed for large yaw angles of the vehicle, where the static coupling over-predicts the aerodynamic loads and in turn the vehicle motion.
In this paper we assess the order of model complexity needed to capture a vehicle behaviour during a transient crosswind event, regarding the interaction of the aerodynamic loads and the vehicle dynamic response. The necessity to perform a full dynamic coupling, including feedback in real-time, instead of a static coupling to capture the vehicle performance both with respect to aerodynamics and the vehicle dynamics is evaluated. The computations are performed for a simplified bus model that is exposed to a transient crosswind. The aerodynamic loads are obtained using Detached Eddy Simulation (DES) with the overset mesh technique coupled to a single-track model for the vehicle dynamics including a driver model with three sets of controller parameters to obtain a realistic scenario. Two degrees of freedom are handled by the vehicle dynamics model; lateral translation and yaw motion. The results show that the full dynamic coupling is needed for large yaw angles of the vehicle, where the static coupling over-predicts the aerodynamic loads and in turn the vehicle motion.
Measurement methods to determine the rolling resistance of tyres during different operation conditions are essential in the work towards more energy efficient vehicles. One of the influential parameters is the tyre temperature distribution, which has a large impact on the rolling resistance. Today, the standardised test procedure to measure rolling resistance is steady-state measurement on drums. However, the steady-state temperature on a drum is not the same as the temperature during ordinary driving conditions. The aim of this work is to develop a measuring method that enables to set a desired measurement temperature, which would create the possibility to study the relationship between tyre temperature and rolling resistance in more detail. The measurement method was developed by the use of a flat track equipment but should be applicable to other rolling resistance measurement equipment such as drums. The resulting method gives a repeatable tyre temperature and rolling resistance and can be used for measurements on tyres heated to a chosen measurement temperature.
Reducing the rolling resistance for future vehicle designs creates a possibility to reduce the fuel consumption and make the future vehicles more economical and ecological. For electric vehicles it is also an enabler to increase their driving range per charge. When optimising for reduced rolling resistance, contradictory requirements such as force generation for maintaining safety and performance need to be considered. Furthermore, it is important to include both the effects of road surface and vehicle, to avoid sub-optimisation regarding only the tyres. A cross-functional conflict on the component level is well known, in form of energy consumption versus wet grip (traffic safety). On the system level, different wheel settings to optimise energy consumption conflicts with vehicle dynamical properties related to traffic safety, such as stability or steer response. The long term vision of the work presented is to create tools for more energy efficient vehicles by reducing the rolling resistance during driving. The first part is to establish a credible measurement method for rolling resistance on road under controlled conditions (lab environment). Today’s existing measurement methods on rolling resistance under laboratory conditions commonly utilise a rotating drum, whose curved surface affects the results. Therefore, rolling resistance influence of vehicle settings such as camber or toe angles is difficult to assess using standard methods, and there is a need for measurements using a more realistic contact patch, which would need a flat surface. The existing unique tyre testing facility at the Swedish National Road and Transport Research Institute, VTI, is used as a base for developing the new rolling resistance set-up. The tyre test facility is today used to determine tyre characteristics such as brake and steering forces. The method to measure rolling resistance with this equipment under highly controlled conditions is under development, and some preliminary results are presented.
For at least 50 years, the interest in understanding and reducing the rolling resistance of pneumatic tyres has been growing. This interest is driven by the need to reduce vehicle fuel consumption and CO2-emissions, for environmental and economic reasons. The amount of rolling resistance generated depends on the vehicle type, tyre properties and operating conditions. The main objective of this literature review is to provide an overview of the most influential operating conditions with respect to rolling resistance, their effects and their connection to different measurement techniques. The examined operating conditions are the inflation pressure, the temperature, the curvature of the test surface, the load, road surface, speed, torque, slip angle and camber angle. In addition, the definition of rolling resistance is investigated, which shows lack of harmony in the literature. There are important areas where little research can be found and where further research would be valuable. Examples of such areas are effects of the torque, slip angle and camber angle on rolling resistance, thorough comparison between flat-surface and drum measurements, effects of temperature difference between laboratory measurements and actual driving on rolling resistance and evaluation of Unrau’s formula for temperature correction of rolling resistance measurements.
While there are many tyre and vehicle dependent factors that affect the rollingresistance, the road properties play also an influential role in the overall resistance on the vehicle.The aim of this study is to develop amodel that can estimate the effect of road roughness on rollingresistance of tyres where both the texture-dependent and independent factors are contributing tooverall rolling resistance. In this paper, a method based on the self-affine fractal surfaces is usedto model realistic road characteristics in order to couple it with a brush based tyre model to beable to study the influence of road roughness on tyre rolling resistance. The simulation resultssuggest that the rolling resistance increases with increased RMS-value and both the macro- andthe micro-texture have an influence on the rolling resistance while the macro-texture effect is moreinfluential. The results of this paper can be related to the estimation of fuel economy on differentroad textures, from macro-texture to micro-texture and further optimisation of road surfaces.