| 1. |
- Albinsson, Anton, 1989, et al.
(författare)
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Estimation of the inertial parameters of vehicles with electric propulsion
- 2016
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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. ; 230:9, s. 1155-1172
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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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| 2. |
- 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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| 3. |
- Albinsson, Anton, 1989, et al.
(författare)
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Validation of vehicle-based tyre testing methods
- 2019
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:1, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- The development process for passenger cars is both time- and resource-consuming. Full vehicle testing is an extensive part of the development process that consumes large amount of resources, especially within the field of vehicle dynamics and active safety. By replacing physical testing with complete vehicle simulations, both the development time and cost can potentially be reduced. This requires accurate simulation models that represent the real vehicle. One major chal- lenge with full vehicle simulation models is the representation of tyres in terms of force and moment generation. The force and moment generation of the tyres is affected by both operating conditions and road surface. Vehicle-based tyre testing offers a fast and efficient way to rescale force and moment tyre models to different road surfaces, in this study the Pacejka 2002 model. The resulting tyre model is sensitive to both the operating conditions during testing and the road surface used. This study investigates the influence of the slip angle sweep rate and road surface on the lateral tyre force characteristics of the fitted tyre model. Tyre models fitted to different manoeuvres are compared and the influence on the full vehicle behaviour is investigated in IPG Carmaker. The results show that by using the wrong road surface, the resulting tyre model can end up outside the tolerances specified by the ISO standard for vehicle simulation model verifi- cation in steady-state cornering. The use of Pacejka 2002 models parameterized in a steady-state manoeuvre to simulate the vehicle behaviour in sine-with-dwell manoeuvres is also discussed.
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| 4. |
- Anistratov, Pavel, et al.
(författare)
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Lane-deviation penalty formulation and analysis for autonomous vehicle avoidance maneuvers
- 2021
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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. ; 235:12, s. 3036-3050
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Tidskriftsartikel (refereegranskat)abstract
- Autonomous vehicles hold promise for increased vehicle and traffic safety, and there are several developments in the field where one example is an avoidance maneuver. There it is dangerous for the vehicle to be in the opposing lane, but it is safe to drive in the original lane again after the obstacle. To capture this basic observation, a lane-deviation penalty (LDP) objective function is devised. Based on this objective function, a formulation is developed utilizing optimal all-wheel braking and steering at the limit of road–tire friction. This method is evaluated for a double lane-change scenario by computing the resulting behavior for several interesting cases, where parameters of the emergency situation such as the initial speed of the vehicle and the size and placement of the obstacle are varied, and it performs well. A comparison with maneuvers obtained by minimum-time and other lateral-penalty objective functions shows that the use of the considered penalty function decreases the time that the vehicle spends in the opposing lane.
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| 5. |
- Berglund, Kim, et al.
(författare)
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Prediction of driveline vibrations caused by ageing the limited slip coupling
- 2016
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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. ; 230:12, s. 1687-1698
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Tidskriftsartikel (refereegranskat)abstract
- The prediction of the wet-clutch service life still remains a challenge for scientists and engineers. Previous research has shown the significance of the wet-clutch friction characteristics on the driveline dynamics. To avoid driveline vibrations an increasing friction coefficient with increasing sliding speed is desirable. Consequently, prediction of the occurrence of driveline vibrations relies on a detailed knowledge of how the friction characteristics are affected by wet-clutch degradation, as well as an understanding of the driveline dynamics. Wet clutches are used in both automatic transmissions and all-wheel-drive systems in cars, where they are referred to as limited slip couplings by manufacturers. Wet clutches used in automatic transmissions are subjected to high slip levels, but for very limited time periods. In all-wheel-drive systems, where the limited slip coupling can be used to control the torque transfer to, for example, the rear wheels, the slip levels are low but continuous. Most wet-clutch research has been performed for clutches in automatic transmissions and not for clutches used in all-wheel-drive systems. Thus, a simulation model was developed to evaluate how different operating conditions of the limited slip coupling influence degradation of the friction characteristics and the tendencies towards driveline vibrations. First, the changes in the friction characteristics with the time of ageing are simulated. The friction characteristics after ageing are used as the input to a simplified driveline model, which is used to evaluate the occurrence of vibrations. It is shown how the developed simulation model can be used as an efficient tool for engineers. The developed simulation model can be used to predict how the operating conditions for the limited slip coupling influence degradation of the friction characteristics.
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| 6. |
- Boyraz Baykas, Pinar, 1981, et al.
(författare)
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Multi-sensor Driver Drowsiness Monitoring
- 2008
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 222:11, s. 2041-2062
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Tidskriftsartikel (refereegranskat)abstract
- A system for driver drowsiness monitoring is proposed, using multi-sensor dataacquisition and investigating two decision-making algorithms, namely a fuzzy inference system(FIS) and an artificial neural network (ANN), to predict the drowsiness level of the driver.Drowsiness indicator signals are selected allowing non-intrusive measurements. The experi-mental set-up of a driver-drowsiness-monitoring system is designed on the basis of the sought-after indicator signals. These selected signals are the eye closure via pupil area measurement,gaze vector and head motion acquired by a monocular computer vision system, steering wheelangle, vehicle speed, and force applied to the steering wheel by the driver. It is believed that, byfusing these signals, driver drowsiness can be detected and drowsiness level can be predicted.For validation of this hypothesis, 30 subjects, in normal and sleep-deprived conditions, areinvolved in a standard highway simulation for 1.5 h, giving a data set of 30 pairs. For designing afeature space to be used in decision making, several metrics are derived using histograms andentropies of the signals. An FIS and an ANN are used for decision making on the drowsinesslevel. To construct the rule base of the FIS, two different methods are employed and comparedin terms of performance: first, linguistic rules from experimental studies in literature and,second, mathematically extracted rules by fuzzy subtractive clustering. The drowsiness levelsbelonging to each session are determined by the participants before and after the experiment,and videos of their faces are assessed to obtain the ground truth output for training thesystems. The FIS is able to predict correctly 98 per cent of determined drowsiness states(training set) and 89 per cent of previously unknown test set states, while the ANN has a correctclassification rate of 90 per cent for the test data. No significant difference is observed betweenthe FIS and the ANN; however, the FIS might be considered better since the rule base can beimproved on the basis of new observations.
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| 7. |
- Bruzelius, Fredrik, 1974-, et al.
(författare)
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Validation of a basic combined slip tyre model for use in friction estimation applications
- 2014
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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. ; 228:13, s. 1622-1629
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Tidskriftsartikel (refereegranskat)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.
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| 8. |
- Fatima, Nowshir, et al.
(författare)
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Water contamination effect in wet clutch system
- 2013
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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. ; 227:3, s. 376-389
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Tidskriftsartikel (refereegranskat)abstract
- Water contamination in wet clutch systems can be a problem since both torque characteristics and wear resistance can be influenced by water presence. The present paper reveals the effect of externally added water on the wet clutch frictional performance. Commercially available standard paper based friction plates and steel separator plates lubricated in commercially available automatic transmission fluid were investigated in a recently developed automated test rig implementing a well confined experimental approach. Frictional response was observed for three different situations with different water amount and water exposure time. There is observed undesirable friction increase with increasing water amount in the system. The rate of increase in friction coefficient does not linearly depend on the amount of added water and this is a noticeable outcome from the common possible water contamination effects like change in lubricant viscosity, inadequate additive performance and weakening of friction material. The more reduced separator plates’ surface roughness (Ra) in a water contaminated clutch system compared to an uncontaminated one can be a reason for the change in friction. It is also shown that different water exposure time has no large impact on the change in friction level and separator plate’s roughness.
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| 9. |
- Franzke, Randi, 1989, et al.
(författare)
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Experimental investigation of the air flow in a simplified underhood environment
- 2022
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 236:10-11, s. 2272 -2282
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a simplified underhood environment is proposed to investigate the air flow distribution in a vehicle-like set-up and provide high quality measurement data that can be used for the validation of Computational Fluid Dynamic methods. The rig can be equipped with two types of front openings representative for electrified vehicles. Furthermore, it is possible to install differently shaped blockages downstream of the fan to imitate large underhood components. The distance between the blockages and the fan can be varied in longitudinal and lateral direction. The measurements are performed with Laser Doppler Anemometry at a fixed distance downstream of the fan. The results show that the lack of an upper grille opening in the configuration for a battery electric vehicle has a notable impact on the flow field in the reference case without any downstream blockage. However, the differences in the flow field between the two front designs become less when a downstream obstruction is present. The longitudinal and lateral position of the blockages have have a minor impact on the flow field compared to the shape of the obstacle itself.
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| 10. |
- Genell, Anders, 1974, et al.
(författare)
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Multi-sensory congruence in vehicle sound quality assessment: effects of vibration and irrelevant emotional primes on affective reactions and evaluations of product sounds
- 2010
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 224:D10, s. 1303-1310
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Tidskriftsartikel (refereegranskat)abstract
- A listening test was performed where a group of professional truck drivers were asked to rate their impressions of binaurally recorded interior truck sound of different levels, while subjected to different vibration levels in the steering wheel and in the foot rest of a truck simulator. The hypothesis was that, if the sound and vibrations had the same relative levels as the original environment inside a real truck cabin, the emotional reactions would not be as negative as if either of the modalities was significantly increased relative to the other. The results indicate some support for this hypothesis. In addition, the effects of irrelevant emotional primes on sound quality assessment were studied. The results are discussed in relation to multi-modal theories of emotional sound design for vehicle interiors.
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