| 1. |
- Albinsson, Anton, 1989, et al.
(författare)
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Design of tyre force excitation for tyre–road friction estimation
- 2017
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 55:2, s. 208-230
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the current tyre–road friction coefficient is essential for future autonomous vehicles. The environmental conditions, and the tyre–road friction in particular, determine both the braking distance and the maximum cornering velocity and thus set the boundaries for the vehicle. Tyre–road friction is difficult to estimate during normal driving due to low levels of tyre force excitation. This problem can be solved by using active tyre force excitation. A torque is added to one or several wheels in the purpose of estimating the tyre–road friction coefficient. Active tyre force excitation provides the opportunity to design the tyre force excitation freely. This study investigates how the tyre force should be applied to minimise the error of the tyre–road friction estimate. The performance of different excitation strategies was found to be dependent on both tyre model choice and noise level. Furthermore, the advantage with using tyre models with more parameters decreased when noise was added to the force and slip ratio.
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| 2. |
- Albinsson, Anton, 1989, et al.
(författare)
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Estimation of the inertial parameters of vehicles with electric propulsion
- 2015
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Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; , s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- More accurate information about the basic vehicle parameters can improve the dynamic control functions of a vehicle. Methods for online estimation of the mass, the rolling resistance, the aerodynamic drag coefficient, the yaw inertia and the longitudinal position of the centre of gravity of an electric hybrid vehicle is therefore proposed. The estimators use the standard vehicle sensor set and the estimate of the electric motor torque. No additional sensors are hence required and no assumptions are made regarding the tyre or the vehicle characteristics. Consequently, all information about the vehicle is available to the estimator.The estimators are evaluated using both simulations and experiments. Estimations of the mass, the rolling resistance and the aerodynamic drag coefficient are based on a recursive least-squares method with multiple forgetting factors. The mass estimate converged to within 3% of the measured vehicle mass for the test cases with sufficient excitation that were evaluated. Two methods to estimate the longitudinal position of the centre of gravity and the yaw inertia are also proposed. The first method is based on the equations of motion and was found to be sensitive to the measurement and parameter errors. The second method is based on the estimated mass and seat-belt indicators.This estimator is more robust and reduces the estimation error in comparison with that obtained by assuming static parameters. The results show that the proposed method improves the estimations of the inertial parameters. Hence, it enables online non-linear tyre force estimators and tyre-model-based tyre–road friction estimators to be used in production vehicles.
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| 3. |
- Albinsson, Anton, 1989, et al.
(författare)
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Evaluation of vehicle-based tyre testing methods
- 2019
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Ingår i: Proceedings of the Institution of Mechanical Engineers. Part D, Transport engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:1, s. 4-17
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Tidskriftsartikel (refereegranskat)abstract
- The demand for reduced development time and cost for passenger cars increases the strive to replace physical testing with simulations. This leads to requirements on the accuracy of the simulation models used in the development process. The tyres, the only components transferring forces from the road to the vehicle, are a challenge from a modelling and parameterization perspective. Tests are typically performed on flat belt tyre testing machines. Flat belt machines offers repeatable and reliable measurements. However, differences between the real world road surface and the flat belt can be expected. Hence, when using a tyre model based on flat belt measurements in full vehicle simulations, differences between the simulations and real prototype testing can be expected as well. Vehicle-based tyre testing can complement flat belt measurements by allowing reparameterization of tyre models to a new road surface. This paper describes an experimental vehicle-based tyre testing approach that aims to parameterize force and moment tyre models compatible with the standard tyre interface. Full-vehicle tests are performed, and the results are compared to measurements from a mobile tyre testing rig on the same surface and to measurements on a flat belt machine. The results show that it is feasible to measure the inputs and outputs to the standard tyre interface on a flat road surface with the used experimental setup. The flat belt surface and the surface on the test track show similar characteristics. The maximum lateral force is sensitive to the chosen manoeuvres, likely due to temperature differences and to vibrations at large slip angles. For tyre models that do not model these effects, it is vital to test the tyres in a manoeuvre that creates comparable conditions for the tyres as the manoeuvre in which the tyre model will be used.
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| 4. |
- Albinsson, Anton, 1989, et al.
(författare)
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Friction utilization for tyre-road friction estimation on snow: an experimental study
- 2017
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Ingår i: 13th International Symposium on Advanced Vehicle Control, AVEC'16. - 9781315265285 ; , s. 541-546
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Konferensbidrag (refereegranskat)abstract
- Friction estimation using effect-based approaches are challenging during normal driving due to the large tyre excitation needed for an accurate estimate. The required excitation level varies for different tyres, road surfaces, road conditions and tyre models used in the estimator. Previous research has investigated the required friction utilization on different surfaces but due to the small sample sizes it is hard to draw any general conclusions. This paper investigates the tyre excitation required to estimate the tyre-road friction coefficient with a generic estimator for 76 different tyres on snow for five different tyre models and for different levels of measurement noise.
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| 5. |
- Albinsson, Anton, 1989, et al.
(författare)
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Identification of tyre characteristics using active force excitation
- 2016
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Ingår i: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015. - : CRC Press. - 9781138028852 ; , s. 501-510
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Konferensbidrag (refereegranskat)abstract
- Knowledge of the maximum tyre-road friction coefficient can improve active safety systems by defining actuator boundaries and adaptable intervention thresholds. Estimation of the coefficient of friction based on tyre response measurements requires large level of force excitation. Under normal driving conditions, manoeuvres with large tyre utilizations are rare. This study investigates a method where wheel torques with opposite signs are applied to the front and rear axle simultaneously. This procedure allows for an intervention with large tyre excitations without disturbing the motion of the vehicle. The intervention is evaluated in simulations and experiments. Further, a method is proposed which does not require measurement of the vehicle longitudinal velocity. The results show that it is possible to estimate the current friction coefficient with the proposed method, although the assumption made in the proposed method makes the friction estimate sensitive to measurement noise on the wheel speed signal.
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| 6. |
- Albinsson, Anton, 1989
(författare)
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Online and Offline Identification of Tyre Model Parameters
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 7. |
- Albinsson, Anton, 1989
(författare)
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Online State Estimation in Electrified Vehicles Linked to Vehicle Dynamics
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electric vehicles have the potential to significantly reduce energy consumption and emissions for personal and commercial road transport and number of electric vehicles is likely to increase in the future due to stricter emission legislations. In order to accelerate market penetration, the competiveness of electric vehicles should increase in comparison to conventional vehicles. Active safety is an area where electric vehicle have a possible advantage over conventional vehicle and that could reduce the number of fatalities and injuries in road traffic accidents. However, the performance of active safety systems today is limited by the knowledge of vehicle state estimates and vehicle parameters, e.g. vehicle speed and the tyre-road friction coefficient. This thesis investigates the potential benefits of using the electric motor as a sensing element to improve state and parameter estimations and thereby also active safety systems. In particular, accurate torque estimation provided by electric propulsion is utilized as an additional source of information. The possibility of using active tyre force excitation for the estimation of the tyre-road friction coefficient is also investigated. The results show that there is a potential to improve the longitudinal and, in some situations, the lateral tyre force estimation using electric motors. However, the estimates are sensitive to errors in the inertial parameters. A method for estimating the vehicle inertial parameters was therefore proposed. The estimate of the vehicle mass converged to within 3% of the measured value for the evaluated test cases. However, the estimation of the longitudinal centre of gravity position and the yaw inertia of the vehicle is sensitive to measurement errors and disturbances. This is mainly due to the weak link between lateral and longitudinal dynamics in normal driving conditions. An alternative method using the seat belt indicators was therefore proposed. This method improves the estimates of these parameters on average when compared to assuming default values. A method to estimate the tyre-road friction coefficient with active tyre force excitation was also proposed. This method enables the estimation of the tyre-road friction coefficient when demanded from an active safety system. Electric motors offer several advantages for active tyre force excitation. The fast response and the ability to apply both positive and negative torque can improve the slip control of the wheels, which is crucial for vehicle stability during the intervention.In summary, the improved wheel torque estimation has the potential to improve the tyre force estimation in both the longitudinal direction directly and in the lateral direction through improved inertial parameter estimation. Furthermore, the electric motor as an actuator provides further opportunities during active tyre force excitation.
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| 8. |
- Albinsson, Anton, 1989, et al.
(författare)
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Required friction utilization for friction estimation on wet asphalt, an experimental study
- 2018
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Ingår i: The Dynamics of Vehicles on Roads and Tracks. - : CRC Press/Balkema. - 9781138035713 ; 1, s. 407-412
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Konferensbidrag (refereegranskat)abstract
- Real-time information about the friction coefficient between the tyre and the road can be used to improve active safety systems and is an enabler for autonomous vehicles. Large tyre force excitation is normally required to obtain an accurate friction estimate. This paper quantifies this requirement for four different tyre models on wet salted asphalt at water freezing temperatures. Cost functions and different tyre models are evaluated and the results are compared to a previous study performed for snow conditions. The suitability of commonly used tyre models for friction estimation on snow and wet asphalt has thus been investigated.
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| 9. |
- Albinsson, Anton, 1989, et al.
(författare)
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Scaling tire models to different road surfaces using an external IMU and K&C measurements
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Accurate simulation models are required for virtual verification of vehicle dynamics and chassis control functions. The force and moment characteristics of tires depend on the road surface. To achieve good simulation and testing correlation accuracy, an accurate tire model that is representative for the actual road surface is required. This study investigates a cost-efficient method to scale Pacejka 2002 models, based on flat belt measurements, to a real road surface using simple instrumentation and static measurements of a test vehicle. The feasibility of the method is illustrated using measurements, where the propagation of measurement error to model error is investigated.
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| 10. |
- Albinsson, Anton, 1989, et al.
(författare)
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Tire Force Estimation Utilizing Wheel Torque Measurements and Validation in Simulations and Experiments
- 2014
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Ingår i: 12th International Symposium on Advanced Vehicle Control (AVEC '14), Tokyo Japan. ; , s. 294-299
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Konferensbidrag (refereegranskat)abstract
- This study investigates a new tire force estimator based on the recursive least square (RLS) method. Tire force estimation with known driving wheel torque is studied and compared to the case with torque estimation from the internal combustion engine. This is motivated by a future scenario with electric propulsion, which reasonably gives improved wheel torque estimations. Sensitivity to vehicle parameters and challenges with individual lateral tire force estimation are also investigated. The results, experimental and simulation data, show good performance and potential for tire force estimation using the RLS method.
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