On line estimation of rolling resistance for intelligent tires

The analysis of a rolling tire is a complex problem of nonlinear elasticity. Although in the technical literature some tire models have been presented, the phenomena involved in the tire rolling are far to be completely understood. In particular, small knowledge comes even from experimental direct observation of the rolling tire, in terms of dynamic contact patch, instantaneous dissipation due to rubber-road friction and hysteretic behavior of the tire structure, and instantaneous grip. This paper illustrates in details a new powerful technology that the research group has developed in the context of the project OPTYRE. A new wireless optical system based on Fiber Bragg Grating strain sensors permits a direct observation of the inner tire stress when rolling in real conditions on the road. From this information, following a new suitably developed tire model, it is possible to identify the instant area of the contact patch, the grip conditions as well the instant dissipation, which is the object of the present work

차량 환경간 통신과 타이어-노면 마찰계수 추정을 고려한 AEBS 알고리즘 개발

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2014. 8. 이경수.자동차 비상제동장치는 자동차 전방의 충돌이 임박했을 경우 자동적으로 브레이크를 작동 시키는 능동안전시스템이다. 기존의 AEBS 알고리즘은 충돌시간을 브레이크를 작동시키기 위한 지표로 사용하였다. 충돌시간은 전방차량과 자차량의 상대속도와 상대거리를 고려하는 지표이다. 본 연구에서는 자동차 비상제동장치와 타이어-노면 마찰 계수 추정을 결합하는 알고리즘에 대하여 제시하였다. 차량 동역학 기반의 타이어-노면 마찰계수 추정 방법을 적용하는 한편 이러한 방법의 한계를 고려하였다. 자동차 시스템은 차량 환경간 통신에 의한 정보와 일반적인 자동차의 센서 시스템을 가지고 있는 것으로 가정하였고 이를 통해서 데이터를 얻어서 추정기가 작동하는 것으로 가정하였다. 이러한 제어 알고리즘에 대하여 CARSIM과 MATLAB simulink를 이용하여 시뮬레이션을 수행하였다.The advanced emergency braking system(AEBS) is the active safety system to decelerate a car automatically when the forward collision is eminent. Conventional AEBS algorithm uses time-to-collision as an index to activate the brake. The time-to-collision considers the relative velocity and the clearance only. In this study, AEBS with tire-road friction coefficient estimation is presented. The vehicle dynamics based tire road friction estimation is applied and its limit is considered. The vehicle system has V2I information and nominal vehicle sensor system for tire-road friction coefficient estimation. CARSIM and MATLAB Simulink based simulation study was conducted.Contents Abstract I List of Figures V List of Tables VI Nomenclature Ⅶ Chapter 1. Introduction 1.1 Research Background 1.2 Research Overview Chapter 2. Tire-road Friction coefficient estimation 2.1 Previous research of tire-road Friction Coefficient Estimation 2.1.1 Tire deflection based friction coefficient estimation 2.1.2 Tire motion based friction coefficient estimation 2.1.3 Vehicle dynamics based friction coefficient estimation algorithm 2.2 Longitudinal stiffness estimation 2.3 Indirect Environmental Information For The Tire-road Friction Coefficient Chapter 3. AEBS control algorithm 3.1 Braking curve model 3.2 Control Algorithm of AEBS 3.2.1 Conventional algorithm of AEBS 3.2.2 Proposed algorithm of AEBS Chapter 4. Simulation Results Chapter 5. Conclusions Bibliography 초 록Maste

OPTYRE—Real time estimation of rolling resistance for intelligent tyres

The study of the rolling tyre is a problem framed in the general context of nonlinear elasticity. The dynamics of the related phenomena is still an open topic, even though few examples and models of tyres can be found in the technical literature. The interest in the dissipation effects associated with the rolling motion is justified by their importance in fuel-saving and in the context of an eco-friendly design. However, a general lack of knowledge characterizes the phenomenon, since not even direct experience on the rolling tyre can reveal the insights of the correlated different dissipation effects, as the friction between the rubber and the road, the contact kinematics and dynamics, the tyre hysteretic behaviour and the grip. A new technology, based on fibre Bragg grating strain sensors and conceived within the OPTYRE project, is illustrated for the specific investigation of the tyre dissipation related phenomena. The remarkable power of this wireless optical system stands in the chance of directly accessing the behaviour of the inner tyre in terms of stresses when a real-condition-rolling is experimentally observed. The ad hoc developed tyre model has allowed the identification of the instant grip conditions, of the area of the contact patch and allows the estimation of the instant dissipated power, which is the focus of this paper

Online and Offline Identification of Tyre Model Parameters

The accelerating development of active safety system and autonomous vehicles put higher requirements on both environmental sensing and vehicle state estimation as well as virtual verification of these systems. The tyres are relevant in this context due to the considerable influence of the tyres on the vehicle motion and the performance boundaries set by the tyres. All forces that the driver use to control the vehicle are generated in the contact patch between the tyre and the road on a normal passenger car. Hence, the performance limits imposed by the tyres should ideally be considered in the active safety systems and in self-driving vehicles. Due to tyres influence on the vehicle motions, they are some of the key components that must be accurately modelled to correlate complete vehicle simulations models with physical testing.This thesis investigates the possibility to estimate the tyre-road friction coefficient during normal driving using active tyre force excitation, i.e. online identification of tyre model parameters. The thesis also investigates the possibility to scale tyre Force and Moment (F&M) models for complete vehicle simulations from indoor tests to real road surfaces using vehicle-based tyre testing, i.e. offline identification of tyre model parameters.For online identification of tyre model parameters, the focus has been on how to perform tyre force excitation to maximize the information about the tyre-road friction coefficient. Furthermore, the required excitation level, as a ratio of the maximum tyre-road friction coefficient, for different road surfaces and tyre models have been evaluated for a larger number of passenger car tyres. The thesis shows the feasibility and benefits of using active tyre force excitations and illustrates its benefits when estimating the tyre-road friction coefficient by identifying nonlinear tyre model parameters. The method shows promising results by offering tyre-road friction estimates when demanded by the driver or an on-board system. This system can also be combined with other tyre-road friction estimates to offer a continuous tyre-road friction estimate, e.g. through car-to-car communication.For offline identification of tyre model parameters, the focus was put on rescaling tyre models from indoor testing to a real-world road surface using vehicle-based tyre testing. Sensors were fitted to the vehicle to measure all inputs and outputs of the Pacejka 2002 tyre model. Furthermore, testing was performed on both different road surfaces and using different manoeuvres for tyre model identification. The effect on the complete vehicle behaviour in simulation when using tyre models based on different manoeuvres and road surfaces was investigated. The results show the importance of using a road surface and manoeuvre that are representative for the road surface and manoeuvre in which the vehicle will be evaluated. The sensitivity to different manoeuvres are mainly related to the changes in tyre properties with tyre surface temperature and the lack of temperature effects in the tyre model. The method shows promising results as an efficient way to rescale tyre models to a new road surface

Analyse der Realnutzung von Elektrofahrzeugen in kommerziellen Flotten zur Definition einer bedarfsgerechten Fahrzeugauslegung

Auf Basis einer Naturalistic Driving Studie mit Elektrofahrzeugen in kommerzieller Nutzung wird eine detaillierte Analyse der Mobilität vorgenommen und daraus eine empirisch begründete bedarfsgerechte Fahrzeugauslegung abgeleitet, die sich auf den Kern der Nutzeranforderungen konzentriert und statistische Ausreißer zu Gunsten einer sparsameren Auslegung ausschließt. Weiterhin werden Realfahrzyklen für Elektrofahrzeuge erarbeitet und das Marktpotential dieser Fahrzeugspezifikation abgeschätzt