| 1. |
- Andersson, Mats, et al.
(author)
-
Road Friction Estimation
- 2007
-
Reports (other academic/artistic)abstract
- This project is part of the Swedish IVSS program. The aim of IVSS is to stimulate research and development for the road safety of the future. Road conditions with low friction have been identified as a frequent cause of traffic accidents. Therefore, technology to automaticallydetect changes in road conditions and alert the driver or take proper actions with active driver support systems would be a key contribution to increased road safety.The aim of this project was to investigate the possibilities to estimate the tire to road friction.Three different approaches have been developed and evaluated, from concept to early prototypes in test vehicles. In the first method, the estimation of the coefficient of friction is based on the forces and torques that are produced at the front tires at cornering maneuvers.The second method is based on a physical model of the tire behavior and estimates road friction from information on the forces that are produced at straight driving. The third method is based on an optical sensor that classifies the road surface ahead of the vehicle.The three methods have been successfully evaluated in proving ground and public road tests in summer and winter conditions with different tires, and have been compared with reference measurements. The conclusion is that all three methods can be used for tire to road frictionestimation and are recommended for further development and industrialization.
|
|
| 2. |
- Bruzelius, Fredrik, et al.
(author)
-
Experimental Validation of the Brush Tire Model
- 2007
-
Conference paper (peer-reviewed)abstract
- The paper presents an experimental validation of the physically based brush-tire model towards the tire behavior in a number of different realistic conditions. Results are presented of measurements performed with summer, winter and studded tires on different road foundations such as wet and dry asphalt, basalt, snow and ice. The purpose behind the validation is to study the possibilities to use the brush model to estimate the friction coefficient from measurements or estimates of the longitudinal tire forces and tire slip. The article both validates the model agreement and investigates the sensitivity of the included tire parameters toward various factors that may change during normal run of the vehicle. The study has been performed within the Road Friction Estimation project that has been a part the IVSS-program financed by the Swedish government and a framework of automotive related companies. The measurements were conducted by VTI, the Swedish National Road and Transport Research Institute using the test truck BV12.
|
|
| 3. |
- Bruzelius, Fredrik, 1974-, et al.
(author)
-
Validation of a basic combined slip tyre model for use in friction estimation applications
- 2014
-
In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 228:13, s. 1622-1629
-
Journal article (peer-reviewed)abstract
- Tyre modelling is an important part of understanding and estimating the tyre-road friction. In this paper a basic steady-state tyre model for the combined-slip case is derived. The model is intended to be used in friction estimations applications, where the model complexity is of high priority. The model, described using only two parameters, is validated with measured data from various conditions and tyre types using mobile measurement equipment. The performance from the measurements suggests that only two parameters are sufficient for the combined-slip case.
|
|
| 4. |
- Gäfvert, Magnus, et al.
(author)
-
A Novel Semi-Empirical Tire Model for Combined Slips
- 2005
-
In: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 43:5, s. 351-384
-
Journal article (peer-reviewed)abstract
- A new tyre-force model for simultaneous braking and cornering is presented, which is based on combining existing empirical models for pure braking and cornering with brush-model tyre mechanics. The aim is to offer an easy-to-use, accurate model for vehicle-handling simulations. On a working tyre the contact patch between the tyre and the road is, in general, divided into an adhesion region where the rubber is gripping the road and a sliding region where the rubber slides on the road surface. The total force generated by the tyre is then composed of components from these two regions. The brush model describes this in a mechanical framework. The proposed model is based on a new method to extract adhesion and sliding forces from empirical pure-slip tyre models. These forces are then scaled to account for the combined-slip condition. The combined-slip self-aligning torque is also described. A particular feature of the model is the inclusion of velocity dependence, even if this is not explicitly present in the empirical pure-slip model. The approach is quite different from most previous combined-slip models, in that it is based on a rather detailed mechanical model in combination with empirical pure-slip models. The model is computationally sound and efficient and does not rely on any additional parameters that depend on combined-slip data for calibration. It can be used in combination with virtually any empirical pure-slip model and in this work the Magic Formula is used in examples. Results show good correspondence with experimental data.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Gäfvert, Magnus, et al.
(author)
-
Implementation and Application of a Semi-Empirical Tire-Model in Multi-Body Simulation of Vehicle Handling
- 2006
-
Conference paper (peer-reviewed)abstract
- This paper describes the implementation and application of a previously published semi-empirical tire-model in a multi-body modeling and simulation environment for vehicle dynamics analysis. The multi-body modeling environment is based on acausal equation descriptions expressed in the high-level language Modelica. This paradigm for modeling is particularly useful for the semi-empirical model. Examples illustrate model characteristics and typical usage
|
|
| 8. |
- Svendenius, Jacob, et al.
(author)
-
A Brush-Model Based Semi-Empirical Tire-Model for Combined Slips
- 2004
-
In: SAE Technical Papers 2004-01-1064. - 0148-7191.
-
Conference paper (other academic/artistic)abstract
- This paper presents a new method to derive the tire forces for simultaneous braking and cornering, by combining empirical models for pure braking and cornering using brush-model tire mechanics. The method is aimed at simulation of vehicle handling, and is of intermediate complexity such that it may be implemented and calibratedby the end user. The brush model states that the contact patch between the tire and the road is divided into an adhesion region where the rubber is gripping the road and a sliding region where the rubber slides on the road surface. The total force generated by the tire is then composed of components from these two regions. In the proposed method the adhesion and the sliding forces are extracted from anempirical pure-slip tire model and then scaled to account for the combined-slip condition. The combined-slip self-aligning torque is described likewise. The separation of the adhesive and sliding forces makes it possible to let the sliding force depend on the relative velocity between the tire and the road. This introduces a velocity dependence in the model, even though this is not explicitly present inthe pure-slip model. The approach is quite different from most previous combined-slip models, in that it is based on a rather detailed mechanical model in combination with empirical pure-slip models. The model is computationally sound and efficient and does not rely on any additional parameters that depend on combined-slip data for calibration. It can be used in combination with virtually any empirical pure-slip model and in this work the Magic Formula is used in examples. Results show good correspondence with experimental data.
|
|
| 9. |
- Svendenius, Jacob, et al.
(author)
-
A Semi-Empirical Tire-Model for Transient Combined-Slip Forces
- 2006
-
In: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:2, s. 189-208
-
Conference paper (other academic/artistic)abstract
- This paper presents a semi-empirical combined-slip tiremodel including transient behavior. The method relies on theassumption that the transient behavior is a result from the dynamicdeformation of the tire carcass and that the interaction between thelateral and longitudinal slip and forces can be explained by thedeformation of the rubber treads. The deformation of the tire carcassmakes the tread slip deviate from the wheel-rim motion in a way thatmay be described by differential equations. A method based onbrush-model tire mechanics is used to construct the combined-slipforces as nonlinearscalings of corresponding pure-slip forces.
|
|
| 10. |
- Svendenius, Jacob, et al.
(author)
-
A Semi-Empirical Tire-Model Including the Effects of Camber
- 2004
-
Reports (other academic/artistic)abstract
- This report presents the addition of camber to a previously published semi-empirical tire model by the same authors. The model combines empirical models for pure braking, cornering and cambering to a model for simultaneous braking, cornering and cambering. It is based on brush-model tire mechanics and aims to offer an easy-to-use accurate model for vehicle handling-simulations. The proposed model is a method to extract and rescale the adhesion and sliding forces from empirical pure-slip tire models to account for the combined-slip condition. The combined-slip self-aligning torque is described likewise. Cambering affects the natural path of the tire carcass on the road surface and deforms the threads to produce an additional force in the lateral direction. Thereby, the proportions of the sliding and adhesive forces changes. The model is computationally sound and efficient and does not rely on any additional parameters that depend on combined-slip data for calibration. It can be used in combination with virtually any empirical pure-slip model. The report also contains a validation of the combined slip behavior towards measurement data from a Jeep Cherokee equipped with Goodyear-wrangler tires.
|
|
