| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- Islam, Manjurul, 1984, et al.
(författare)
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A comparative study of multi-trailer articulated heavy-vehicle models
- 2014
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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. ; , s. 1-29
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides valuable guidelines on the selection of dynamic vehicle models for control algorithm development, design optimization and linear stability analysis for multi-trailer articulated heavy vehicles with active safety systems. The validation of yaw-plane and yaw–roll models of a tractor–two-semitrailer combination using the TruckSim software package is presented in this paper. A linear four-degree-of-freedom yaw-plane model and a linear seven-degree-of-freedom yaw–roll model of the vehicle were generated, compared and evaluated. The linear models of the multi-trailer articulated heavy vehicle yield numerical simulation results which are validated by comparing with those obtained from the corresponding non-linear TruckSim model. This paper also includes eigenvalue and frequency-response analysis of the linear models to estimate the unstable motion modes and to predict the unique dynamic features of the multi-trailer articulated heavy vehicle in the frequency domain. A benchmark investigation of the models was performed to examine the fidelity, the complexity and the applicability of the linear models.
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| 5. |
- Kharrazi, Sogol, 1980, et al.
(författare)
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A generic controller for improving lateral performance of heavy vehicle combinations
- 2013
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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. ; 227:D5, s. 619-642
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Tidskriftsartikel (refereegranskat)abstract
- A generic controller for improving the lateral performance of heavy vehicle combinations by steering the axles of the towed units is proposed. The lateral performance of nine heavy vehicle combinations, including conventional combinations and existing and prospective longer combinations, are studied with and without the controller. The performance of the passive vehicles clearly indicates a need for improvements, which can be achieved by the proposed controller. The results obtained for controller verification in the frequency and time domains demonstrate that the controller reduces the yaw rate rearward amplification and off-tracking of all studied vehicles significantly, and diminishes trailer swings without reducing manoeuvrability. Furthermore, as a by-product, it moderately reduces the lateral acceleration rearward amplification. The improvements obtained by the proposed controller can promote the use of longer combination vehicles in traffic, which will result in a reduction of congestion, as well as substantial environmental and economic benefits.
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| 6. |
- Klomp, Matthijs, 1976, et al.
(författare)
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On optimal recovery from terminal understeer
- 2014
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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. ; 228:4, s. 412-425
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of terminal understeer and its mitigation via integrated brake control. The scenario considered is when a vehicle enters a curve at a speed that is too high for the tyre-road friction limits and an optimal combination of braking and cornering forces is required to slow the vehicle down and to negotiate the curve. Here, the driver commands a step steering input, from which a circular arc reference path is inferred. An optimal control problem is formulated with an objective to minimize the maximum off-tracking from the reference path, and two optimal control solutions are obtained. The first is an explicit analytical solution for a friction-limited particle; the second is a numerically derived open-loop brake control sequence for a nonlinear vehicle model. The particle solution is found to be a classical parabolic trajectory associated with a constant acceleration vector of the global mass center. The independent numerical optimization for the vehicle model is found to approximate closely the kinematics of the parabolic path reference strategy obtained for the particle. Using the parabolic path reference strategy, a closed-loop controller is formulated and verified against the solution from numerical optimization. The results are further compared with understeer mitigation by yaw control, and the parabolic path reference controller is found to give significant improvement over yaw control for this scenario.
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| 7. |
- Körning-Ljungberg, Jessica, et al.
(författare)
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Psychological effects of combined noise and whole body vibration : a review and avenues for future research
- 2010
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Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - 0954-4070 .- 2041-2991. ; 224:D10, s. 1289-1302
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Tidskriftsartikel (refereegranskat)abstract
- Vehicle drivers are often exposed to noise, whole-body vibrations (WBV) and mental loads, but the knowledge of how combined effects from multiple environmental stressors affect mental load is sparse. Studies have shown that the effect of one factor may be different than the effect of two factors presented together. For example, negative combined effects have been found when people perform mental tasks (e.g., Sommer and Harris, 1973; Harris and Schoenberger, 1980), as well as in subjective ratings (e.g., Ljungberg, Neely, Lundström, 2004). Although some of the studies investigating the combined effects of noise and WBV suffer from low ecological validity and few have investigated the possible effects on higher cognitive functions. Applying methods well-known to be sensitive to sound exposures by using serial recall tasks (e.g., Jones, Madden & Miles, 1992) as well as methods developed in the studies of noise after-effects (e.g., Glass & Singer, 1972) may be a way to continue the research field of combined effects of noise and WBV
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| 8. |
- Lindström, Mikael, et al.
(författare)
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A study of combustion and emission formation characteristics during production engine transients using optical diagnostics
- 2011
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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. ; 225:D9, s. 1290-1303
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Tidskriftsartikel (refereegranskat)abstract
- In order to identify some of the special combustion and emission formation phenomena that occur in a turbocharged heavy-duty diesel engine during transient operation, the transient strategy of a production engine has been characterized at four different engine speeds. From each transient some points have been selected for further investigation by recreating these load points as steady-state points in a single-cylinder engine. This allows the emissions to be measured with a high degree of accuracy. An endoscope which makes it possible to evaluate flame temperatures was used in both engines. An empirically derived method of calculating nitric oxide (NO) formation from a combination of measured flame temperature, calculated gas temperature, and heat release rate has been developed and applied. This provides an increased understanding of combustion and emission formation phenomena during transient operation. An optical engine was also used to provide a full combustion chamber view for some of the operating points, and a specially developed software was used to calculate temperature distributions based on high-speed camera colour information. The NO formation formula was applied on these images, which resulted in spatially resolved NO formation distributions.
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| 9. |
- Lundström, Andreas, 1980, et al.
(författare)
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Modelling of urea gas phase thermolysis and theoretical details on urea evaporation
- 2011
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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. ; 225:10, s. 1392-1398
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Tidskriftsartikel (refereegranskat)abstract
- A model study of droplet decomposition of a urea–water solution (UWS) for selective catalytic reduction applications (SCR) has been undertaken. A new vapour pressure equation for urea has been adopted to predict the rate of urea evaporation. The vapour pressure above liquid urea is obtained by extrapolating the vapour pressure above solid urea. Gas phase decomposition of urea into ammonia and isocyanic acid is further assumed to be fast, dictating the boundary conditions for the evaporation process. The rate of UWS evaporation is compared to recently published data and shows good agreement. A set of Antoine parameters was fitted to the derived vapour pressure to facilitate future simulations.
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| 10. |
- Miller, Jonathan, et al.
(författare)
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Designing and testing an advanced pneumatic braking system for heavy vehicles
- 2013
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 227:8, s. 1715-1729
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Tidskriftsartikel (refereegranskat)abstract
- Heavy goods vehicles exhibit poor braking performance in emergency situations when compared to other vehicles. Part of the problem is caused by sluggish pneumatic brake actuators, which limit the control bandwidth of their antilock braking systems. In addition, heuristic control algorithms are used that do not achieve the maximum braking force throughout the stop. In this article, a novel braking system is introduced for pneumatically braked heavy goods vehicles. The conventional brake actuators are improved by placing high-bandwidth, binary-actuated valves directly on the brake chambers. A made-for-purpose valve is described. It achieves a switching delay of 3–4 ms in tests, which is an order of magnitude faster than solenoids in conventional anti-lock braking systems. The heuristic braking control algorithms are replaced with a wheel slip regulator based on sliding mode control. The combined actuator and slip controller are shown to reduce stopping distances on smooth and rough, high friction (μ = 0.9) surfaces by 10% and 27% respectively in hardware-in-the-loop tests compared with conventional ABS. On smooth and rough, low friction (μ = 0.2) surfaces, stopping distances are reduced by 23% and 25%, respectively. Moreover, the overall air reservoir size required on a heavy goods vehicle is governed by its air usage during an anti-lock braking stop on a low friction, smooth surface. The 37% reduction in air usage observed in hardware-in-the-loop tests on this surface therefore represents the potential reduction in reservoir size that could be achieved by the new system.
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| 11. |
- Tajadura, Ana, 1979, et al.
(författare)
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Whole-body vibration influences on sound localization in the median plane
- 2010
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 224:10, s. 1311-1320
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates human multisensory perception of sound and vibration, highlighting its potential impact in the design of novel user interfaces, including those used in the automobile industry. Specifically, the present study investigates whether frontback sound localization could be altered by concurrent whole-body vibration. Previous research has shown that, when auditory and tactile stimuli are presented synchronously but from different positions, the perceived location of the auditory event is mislocalized of the tactile stimulus. Here, sounds were presented at the front or the back of participants, in isolation, or together with vibrations. Participants made a three-alternative forced choice regarding their perceived location of the sounds.Results indicate that front-back sound localization was affected by the presence of concurrent vibrations, which biased the localization of front sounds towards the partipants' rear space. Since the perceived location of events modulates the perceivers' understanding and involvement in these events, the possibility of manipulating the location of sound events using vibrations has a potential for the design of multisensory interfaces such as those included in automotive applications, where it is strongly needed to capture the attention of drivers, to provide navigational information, and to reduce sensory load.
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| 12. |
- Tornehed, P., et al.
(författare)
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Lubricant ash particles in diesel engine exhaust. Literature review and modelling study
- 2011
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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. ; 225:D8, s. 1055-1066
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Forskningsöversikt (refereegranskat)abstract
- Reducing particulate emissions from diesel engines has been a concern in recent decades. The increasing use of diesel particulate filters (DPFs) has highlighted the importance of predicting ash emissions from lubricant, since ash accumulates in DPFs. Ash accumulation will increase the pressure drop across the filter, and thereby also the fuel consumption, eventually necessitating filter cleaning or replacement. This paper examines the ash transfer rate, calculated as accumulated ash divided by calculated ash consumption (oil consumption times oil ash content). Three times 500 hours of ash accumulation testing was performed on a Scania heavy-duty diesel engine; in addition, the relevant literature was reviewed. The main results of the study are: (a) the main contributor to ash particulate emissions is lubricant ash; (b) the oil ash transfer rate was found to be oil specific; testing indicated transfer rates of 38-59 per cent; (c) the slight increase in ash transfer rate when reducing the engine load indicated that the load might be dependent on the oil ash transfer rate, although the effect was clearly lower than that of the changing oil.
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| 13. |
- Wahlström, Johan, et al.
(författare)
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Modelling diesel engines with a variable-geometry turbocharger and exhaust gas recirculation by optimization of model parameters for capturing non-linear system dynamics
- 2011
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Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Journals online. - 0954-4070 .- 2041-2991. ; 225:7, s. 960-986
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Tidskriftsartikel (refereegranskat)abstract
- A mean-value model of a diesel engine with a variable-geometry turbocharger (VGT) and exhaust gas recirculation (EGR) is developed, parameterized, and validated. The intended model applications are system analysis, simulation, and development of model-based control systems. The goal is to construct a model that describes the gas flow dynamics including the dynamics in the manifold pressures, turbocharger, EGR, and actuators with few states in order to obtain short simulation times. An investigation of model complexity and descriptive capabilities is performed, resulting in a model that has only eight states. A Simulink implementation including a complete set of parameters of the model are available for download. To tune and validate the model, stationary and dynamic measurements have been performed in an engine laboratory. All the model parameters are estimated automatically using weighted least-squares optimization and it is shown that it is important to tune both the submodels and the complete model and not only the submodels or not only the complete model. In static and dynamic validations of the entire model, it is shown that the mean relative errors are 5.8 per cent or lower for all measured variables. The validations also show that the proposed model captures the system properties that are important for control design, i.e. a non-minimum phase behaviour in the channel EGR valve to the intake manifold pressure and a non-minimum phase behaviour, an overshoot, and a sign reversal in the VGT to the compressor mass flow channel, as well as couplings between channels.
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| 14. |
- Westlund, Anders, et al.
(författare)
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A one-dimensional model for heat release rate and emission formation in diesel engines based on correlations for entrainment rate, lift-off length and ignition delay : Validation for transient conditions
- 2012
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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. ; 226:D9, s. 1243-1258
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Tidskriftsartikel (refereegranskat)abstract
- A simplified one-dimensional model for combustion and emission formation in diesel engines has been developed in a project where the long-term objective is to predict the emissions during transient operation. The models are intended to be used as a tool for pre-development of after-treatment systems and for offline calibration of engine controls. These applications imply that the final model must be both computationally inexpensive and comprehensive. The model is based on a correlation for the air entrainment rate which is applied to a discretized injection event. On this, the combustion rate and the emission formation rate are imposed with simple models. In this publication, the model is validated for the targeted conditions and transient operation. The model is based on a previously presented model which was evaluated for steady state conditions. The model presented here has been modified to address the shortcomings that were identified in the previous evaluation. The model was able to predict the heat release rate and the emissions of nitrogen oxide ( NO) and soot with reasonable accuracy and also the requirement regarding the computational time was met. The average time for simulation of one engine cycle was approximately 3 s on a standard laptop.
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| 15. |
- Yang, Derong, 1985, et al.
(författare)
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Optimized brake-based control of path lateral deviation for mitigation of secondary collisions
- 2011
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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. ; 225:D12, s. 1587-1604
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers brake-based lateral control of a passenger vehicle, for reducing secondary collision risk following an initial impact in a traffic accident. Since secondary collisions are associated with deviations from the original travel path, the control problem is formulated via brake control sequences that minimize lateral path deviation. Optimal sequences are found not to conform to any simple control mode; sometimes all brakes are released, sometimes all wheels are locked, or the brakes may be applied in differential mode. In general, the optimal strategy combines several such actuation modes, and analysis shows it is related to the utilization of instantaneous vehicle force and moment capacity, indicating that a closed-loop control strategy may be developed based on the real-time estimation of tyre force limits during the post-impact event. Yaw motion control is related to response discontinuity and multiple equilibria found in the optimal response - a small change in initial yaw velocity generates large changes in the ensuing vehicle motion and thus in the aimed equilibrium point of the vehicle's orientation. Overall it is found that braking control strongly influences the post-impact path of the impacted vehicle, and may therefore form the basis of a practical system for avoiding secondary collisions in future traffic accidents.
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| 16. |
- Ye, X., et al.
(författare)
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Design and implementation of a real-time power management strategy for a parallel hybrid electric bus
- 2014
-
Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070.
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Tidskriftsartikel (refereegranskat)abstract
- A real-time energy management strategy derived from an equivalent consumption minimization strategy for a parallel hybrid electric bus is introduced. Although an equivalent consumption minimization strategy is a near-optimal control strategy for the power management problems of hybrid electric vehicles, the computation cost and the driveability requirements are still barriers for it to be directly implemented on real-time controllers. This paper analyses the controller characteristics of the equivalent consumption minimization strategy based on the Willans line model for an internal-combustion engine and an electric motor. A two-step method is proposed to simplify and approximate the standard equivalent consumption minimization strategy controller. The strategy for the proposed controller, which is calledthe Willans line–equivalent consumption minimization strategy, can reduce the computation cost of optimization and can guarantee near-optimum fuel economy, while improving the vehicle driveability. The proposed controller is then validated by offline simulation and an onboard bench test. A backward simulation is conducted to test the fuel economy performance of the controller simplified from the two steps, together with dynamic programming and an equivalent consumption minimization strategy based on look-up tables. Then the controller is tuned by a high-fidelity forward simulationto explore the trade-off between the fuel economy and the driveability. Finally, a bench test with real powertrain components is presented to illustrate the effectiveness of the proposed methodology.
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