| 1. |
- Dankowicz, H., et al.
(författare)
-
Control of near-grazing dynamics in impact oscillators
- 2005
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Ingår i: Proceedings of the Royal Society. Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-5021 .- 1471-2946. ; 461:2063, s. 3365-3380
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Tidskriftsartikel (refereegranskat)abstract
- A method is presented for controlling the persistence of a local attractor near a grazing periodic trajectory in a piecewise smooth dynamical system in the presence of discontinuous jumps in the state associated with intersections with system discontiunities. In particular, it is shown that a discrete, linear feedback strategy may be employed to retain the existence of an attractor near the grazing trajectory, such that the deviation of the attractor from the grazing trajectory goes to zero as the system parameters approach those corresponding to grazing contact. The implementation relies on a local analysis of the near-grazing dynamics using the concept of discontinuity mappings. Numerical results are presented for a linear and a nonlinear oscillator.
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| 2. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
A Multi-Line Brush Based Tyre Model to Study the Rolling Resistance and Energy Loss
- 2015
-
Ingår i: Proceedings of 4th International Tyre Colloquium. - 9781844690329
-
Konferensbidrag (refereegranskat)abstract
- This study aim to develop a three dimensional multi-line brush based tyre model for investigating the rolling resistance and energy loss in tyres. The losses in the model are characterised by the external losses originated from the sliding phenomenon in the tyre contact patch, and the internal losses due to the tyre viscoelastic nature which is employed by a rubber model. The Extended Brush tyre Model (EBM) proposed in this work can be used to estimate the dissipated energy and the rolling resistance under different driving manoeuvres and wheel conditions. This paper focuses on the estimation of energy loss and in-plane rolling resistance.
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| 3. |
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| 4. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
Energy Efficiency Analyses of a Vehicle in Modal and Transient Driving Cycles including Longitudinal and Vertical Dynamics
- 2017
-
Ingår i: Transportation Research Part D. - : Elsevier. - 1361-9209 .- 1879-2340. ; 53, s. 263-275
-
Tidskriftsartikel (refereegranskat)abstract
- The growing concerns about the environmental issues caused by vehicles and a strive forbetter fuel economy, urge the legislators to introduce conservative regulations on vehicletesting and homologation procedures. To have accurate evaluations, driving cycles thatcan sufficiently describe the vehicles’ conditions experienced during driving is a prerequisite.In current driving cycles there are still some issues which are disregarded. The aim ofthe presented work is to study the contribution of chassis and vehicle dynamics settings ontyre rolling loss in comparison with the original assumptions made in the NEDC, FTP andHWFET driving cycles. A half-car model including a semi-physical explicit tyre model tosimulate the rolling loss is proposed. For the chosen vehicle and tyre characteristics,depending on the specific chassis settings and considered driving cycle, considerable differenceup to 7% was observed between the energy consumption of the proposed- and conventionalapproach. The current work aims to provide the legislators with a betterinsight into the real effects of chassis and vehicle dynamics during the certification processto further improve the test related procedures required for homologation such as generationof road load curves. I.e., the aim is not to provide a new homologation process, sincethere are also other effects such as road roughness and tyre temperature that need to beconsidered. The results are also of interest for the vehicle manufacturers for further considerationsduring test preparation as well as in the development phase in order to reduce theenvironmental impacts.
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| 5. |
- Davari, Mohammad Mehdi
(författare)
-
Exploiting over-actuation to reduce tyre energy losses in vehicle manoeuvres
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to environmental and economic challenges road vehicles need bettersolutions to reduce energy consumption. Improvement in tyre rolling e-ciency is one of the key enablers for lower energy consumption. The shifttowards electrication and intelligent driving creates new opportunities todevelop energy-ecient vehicles. For instant over-actuated vehicles whichenables dierent objectives such as safety, performance and energy e-ciency to be fullled during a manoeuvre. The objective of this thesis is todevelop a simulation environment to simulate the energy dissipated fromthe tyre in order to investigate the potential to controlling dierent chassisparameters to reduce rolling losses during driving.The rst part of the thesis is dedicated to develop a high-delity semi-physical non-linear tyre model called the Extended Brush Tyre Model(EBM) to be used for energy studies in vehicle dynamics simulations andlater answer whether it is reasonable to believe that there is any potentialto reduce the rolling loss, and thereby energy consumption, using over-actuation.In the second part of the thesis the benets of over-actuation are invest-igated to enable rolling loss reduction. A control strategy using camber-sideslip control (CSC) is proposed. The allocation problem is solved in the formof an optimisation problem using Dynamics Programming (DP) and ModelPredictive Control (MPC). Exploiting the function for a chosen vehicle ina simulation environment shows a signicant improvement of about 60% inrolling loss reduction while maintaining path tracking. Also by using thisfunction the tyre forces can be distributed more evenly while maintainingthe global force, which results in an increase in the available tyre forcesthat is especially benecial when driving at the limit. It is revealed thatoptimising the vehicle manoeuvre from an energy perspective is sometimesin con ict with the safety demand, thus the energy and safety criteria needto be considered simultaneously during optimisation.Finally, experimental studies using an over-actuated concept vehicleconrmed that the CSC function can reduce overall energy consumptionduring low velocity manoeuvres up to about 13%. By increasing the speed,the saving potential decreases but the contribution is nonetheless of signi-cance. The developed simulation environment, including the EBM, willenable future studies of dierent solutions using over-actuation to reducerolling losses in dierent types of vehicles and driving tasks.
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| 6. |
- Davari, Mohammad Mehdi, et al.
(författare)
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Extended Brush Tyre Model to Study Rolling Loss in Vehicle Dynamics Simulations
- 2017
-
Ingår i: International Journal of Vehicle Design. - : InderScience Publishers. - 0143-3369 .- 1741-5314. ; 73:4, s. 255-280
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a semi-physical tyre model that enables studies of rolling loss in combination with vehicle dynamic simulations. The proposed model, named extended brush tyre model (EBM), takes the effects of driving conditions, wheel alignment, and tyre materials into account. Compared to the basic brush tyre model, EBM includes multiple numbers of lines and bristles as well as integrated rubber elements into the bristles. The force and moment characteristics of the model are shown to have a good correlation with the Magic Formula tyre model and experimental data. The numerically estimated rolling resistance coefficients under different conditions are compared to findings in the literature, FE-simulations and experiments. The model can capture some aspects that are not covered by the available literature and experimental observations such as camber effect on rolling loss. EBM can be used as a platform for future studies of rolling loss optimisation using active chassis control.
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| 7. |
- Davari, Mohammad Mehdi, et al.
(författare)
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Investigating the potential of wheel corner modules in reducing rolling resistance of tires
- 2014
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Ingår i: FISITA 2014 World Automotive Congress - Proceedings. - : FISITA.
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Konferensbidrag (refereegranskat)abstract
- The improvement in tire rolling efficiency is one of the key elements to optimize the fuel economy and thereby reduce the vehicle emissions. Earlier efforts to reduce the rolling resistance have mainly been focusing on new materials in the tire compounds. The overall research aim of this study is to present the potentials of implementing innovative chassis concepts with the focus on Wheel Corner Modules (WCM) by describing the possibilities in affecting rolling resistance and relating them to previous research findings. The core idea of the concept is to actively control and actuate all degrees of freedom in the wheel i.e. implementing steering, suspension and propulsion functions into a unique module which can be implemented in each corner of the vehicle. Using this concept the limitations of traditional wheel kinematics can be resolved extensively. This article presents the first step towards creating a vehicle simulation model that can show how the WCM functionality can influence the rolling resistance. A model of loss is chosen after analysing the behaviour of a three different rubber models and then implemented into a brush tire model. An effective way, but less complicated compared to current methods, to introduce the loss into tire model is presented. In conventional suspensions, the design is compromising between for example safety, comfort and rolling resistance, etc. at all driving conditions. However, using the WCM, the possibility of achieving a better compromise between those objectives is possible.Finally, based on WCM functionalities a plausible control architecture is proposed.
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| 8. |
- Davari, Mohammad Mehdi, et al.
(författare)
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Investigating the Potential of Wheel Corner Modules in Reducing Rolling Resistance of Tyres
- 2014
-
Ingår i: Proceedings of FISITA "14 World Automotive Congress, Maastricht, Netherlands (2014).
-
Konferensbidrag (refereegranskat)abstract
- The improvement in tire rolling efficiency is one of the key elements to optimize the fuel economy and thereby reduce the vehicle emissions. Earlier efforts to reduce the rolling resistance have mainly been focusing on new materials in the tire compounds. The overall research aim of this study is to present the potentials ofimplementing innovative chassis concepts with the focus on Wheel Corner Modules (WCM) by describing thepossibilities in affecting rolling resistance and relating them to previous research findings. The core idea of theconcept is to actively control and actuate all degrees of freedom in the wheel i.e. implementing steering,suspension and propulsion functions into a unique module which can be implemented in each corner of the vehicle. Using this concept the limitations of traditional wheel kinematics can be resolved extensively. This article presents the first step towards creating a vehicle simulation model that can show how the WCM functionality can influence the rolling resistance. A model of loss is chosen after analysing the behaviour of three different rubber models and then implemented into a brush tire model. An effective way, but less complicatedcompared to current methods, to introduce the loss into tire model is presented. In conventional suspensions, thedesign is compromising between for example safety, comfort and rolling resistance, etc. at all drivingconditions. However, using the WCM, the possibility of achieving a better compromise between those objectivesis possible. Finally, based on WCM functionalities a plausible control architecture is proposed.
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| 9. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
Rolling loss analysis of combined camber and slip angle control
- 2016
-
Konferensbidrag (refereegranskat)abstract
- The objective of this work is to present a new functionality of over-actuated systems, such as Wheel Corner Modules, to reduce the rolling loss in vehicles. The findings are based on numerical simulations using a bicycle model coupled with a newly proposed tyre model which is capable of simulating the tyre losses during vehicle motions. The results show that for the considered vehicle in the considered manoeuvre the rolling loss can be reduced about 25–40% by proper control of camber and slip angle combinations, while still maintaining the vehicle performance.
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| 10. |
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| 11. |
- Edrén, Johannes, 1983-, et al.
(författare)
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Energy efficient cornering using over-actuation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This work deals with utilisation of active steering and propulsion on individual wheels in order to improve a vehicle’s energy efficiency during a double lane change manoeuvre at moderate speeds. Through numerical optimization, solutions have been found for how wheel steering angles and propulsion torques should be used in order to minimise the energy consumed by the vehicle travelling through the manoeuvre. The results show that, for the studied vehicle, the cornering resistance can be reduced by 10% compared to a standard vehicle configuration. Based on the optimization study, simplified algorithms to control wheel steering angles and propulsion torques that are more energy efficient are proposed. These algorithms are evaluated in a simulation study that includes a path tracking driver model and an energy efficiency improvement of 6-9% based on a combined rear axle steering and torque vectoring control during cornering is found. The results indicate that in order to improve energy efficiency for a vehicle driving in a non-safety-critical situation the force distribution should be shifted towards the front wheels.
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| 12. |
- Edrén, Johannes, et al.
(författare)
-
Energy efficient cornering using over-actuation
- 2019
-
Ingår i: Mechatronics (Oxford). - : Elsevier Ltd. - 0957-4158 .- 1873-4006. ; 59, s. 69-81
-
Tidskriftsartikel (refereegranskat)abstract
- This work deals with utilisation of active steering and propulsion on individual wheels in order to improve a vehicle's energy efficiency during a double lane change manoeuvre at moderate speeds. Through numerical optimisation, solutions have been found for how wheel steering angles and propulsion torques should be used in order to minimise the energy consumed by the vehicle travelling through the manoeuvre. The results show that, for the studied vehicle, the energy consumption due to cornering resistance can be reduced by approximately 10% compared to a standard vehicle configuration. Based on the optimisation study, simplified algorithms to control wheel steering angles and propulsion torques that results in more energy efficient cornering are proposed. These algorithms are evaluated in a simulation study that includes a path tracking driver model. Based on a combined rear axle steering and torque vectoring control an improvement of 6–8% of the energy consumption due to cornering was found. The results indicate that in order to improve energy efficiency for a vehicle driving in a non-safety-critical cornering situation the force distribution should be shifted towards the front wheels.
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| 13. |
- Edrén, Johannes, 1983-
(författare)
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Exploring force allocation control of over actuated vehicles
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the concern for environmental changes and diminishing oil resources grows more and more, the trend of new vehicle concepts now includes full electric or partly electric propulsion systems. The introduction of electric power sources enables more advanced motion control systems due to electrification of the vehicle's actuators, such as individual wheel steering and in wheel hub motors. This can enable a control methodology that uses different chassis control strategies into a system that will be able to fully utilise the vehicle. Due to this, future vehicles can be more optimised with respect to energy consumption, performance and active safety. Force allocation control is a method that distributes the wheel forces to produce the desired response of the vehicle. In order to evaluate if this methodology can be implemented in future series production vehicles, the aim of this work is to explore how force allocation control can be utilised in a real vehicle to improve vehicle dynamics and safety. In order to evaluate different approaches for generic vehicle motion control by optimization, modelling and simulation in combination with real vehicle experiments will be needed to fully understand the more complex system, especially when actuator dynamics and limitations are considered. The use of a scale prototype vehicle represents a compromise between development cost, efficiency and accuracy, as it allows realistic experiments without the cost and complexity of full vehicle test. Moreover since the vehicle is unmanned it allows studies of at-the-limit situations, without the safety risks in full vehicle experiments. A small scale prototype vehicle (Hjulia) has been built and equipped with autonomous corner module functionality that enables individual control of all wheels. A cost effective force allocation control approach has been implemented and evaluated on the prototype vehicle, as well as in vehicle simulation. Results show improvement of stopping distance and vehicle stability of a vehicle during split-m braking. The aspects of vehicle dynamic scaling are also discussed and evaluated, as it is important to know how the control implementation of small scale prototype vehicles compares with full size vehicles. It is shown that there is good comparison between vehicles of different scales, if the vertical gravitational acceleration is adjusted for. In Hjulia, gravity compensation is solved by adding a specific lifting rig. Studies of vehicles considering optimal path tracking and available actuators are also made to evaluate control solutions of evasive manoeuvres at low and high friction surfaces. Results show differences in how the forces are distributed among the wheels, even though the resulting global forces on the vehicle are approximated to be scaled by friction. Also it is shown that actuator limitations are critical in at-the-limit situations, such as an obstacle avoidance manoeuvre. As a consequence these results will provide good insights to what type of control approach to choose to handle a safety critical situation, depending on available actuators. The built prototype vehicle with implemented force allocation control has shown to be a useful tool to investigate the potential of control approaches, and it will be used for future research in exploring the benefits of force allocation control.
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| 14. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
Implementation and evaluation of force allocation control of a down-scaled prototype vehicle with wheel corner modules
- 2013
-
Ingår i: International Journal of Vehicle Systems Modelling and Testing. - 1745-6436. ; 8:4, s. 335-363
-
Tidskriftsartikel (refereegranskat)abstract
- The implementation of wheel corner modules on vehicles creates new possibilities of controlling wheel forces through the utilisation of multiple actuators and wheel motors. Thereby new solutions for improved handling and safety can be developed. In this paper, the control architecture and the implementation of wheel slip and chassis controllers on a down-scaled prototype vehicle are presented and analysed. A simple, cost-effective force allocation algorithm is described, implemented and evaluated in simulations and experiments. Straight line braking tests were performed for the three different controller settings individual anti-lock brakes (ABS), yaw-torque-compensated ABS and force allocation using both wheel torque and steering angle control at each wheel. The results show that force allocation is possible to use in a real vehicle, and will enhance the performance and stability even at a very basic level, utilising very few sensors with only the actual braking forces as feedback to the chassis controller.
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| 15. |
- Edrén, Johannes, 1983-
(författare)
-
Motion modelling and control strategies of over-actuated vehicles
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the growing concern for environmental change and uncertain oil resources, the development of new vehicle concepts will in many cases include full or partial electric propulsion. The introduction of more advanced powertrains enables vehicles that can be controlled with a variety of electric actuators, such as wheel hub motors and individual steering. With these actuators, the chassis can be enabled to adjust its properties depending on the driving situation.Manoeuvring of the vehicle, using for example electric propulsion, braking, suspension, steering and camber control may also allow a variety of combinations which, if properly utilised, can increase the outer limits of vehicle performance and safety. The fact that the vehicle has a greater number of actuators than required to control a certain number of degrees of freedom is called over-actuation. Since there is a great need for energy optimised vehicles, energy efficient control is also required. For this reason, this work is about the allocation of wheel forces can improve safety, performance and energy efficiency in future electrified vehicles in different driving situations.Studies of optimally controlled vehicles show that performance, safety and efficiency can be improved by utilising available actuators in over-actuated vehicles. Path tracking and optimal actuator control signals are evaluated in evasive manoeuvres at low and high friction surfaces. The results show how the forces are distributed differently among the wheels, even though the resulting global forces on the vehicle are similar. Optimal control of camber angles and active suspension show that vehicle performance and safety can be greatly improved. The limits of tyre forces can be increased and better utilised in a way that a passive system is unable to achieve. Actuator performance is also shown to be important, however even low actuator performance is shown to be sufficient to improve vehicle performance considerably. Energy efficiency is also improved as unnecessary vehicle motions are minimised during normal driving and wheel forces are used in a better way.Simplified algorithms to control available actuators, such as wheel angles, vertical actuation and propulsion torques, have been developed, based on the analysis of the results of the optimisation studies. Analyses of the impact of these simplifications have been made. For the cases studied, it has been shown that it is possible to get significantly better performance at reasonable levels of actuator performance and control complexity. This helps to simplify the introduction of this technology in electrified vehicles.Control allocation is a method that distributes the wheel forces to produce the desired response of the vehicle. Simplified control allocation algorithms are proposed that allocate wheel forces in a way that resembles the behaviour of the optimisation solutions. To be able to evaluate the applicability of this methodology for implementation in vehicles, a small-scale prototype vehicle with force allocation control possibilities has been designed and built. The vehicle is equipped with autonomous corner module functionality that enables individual control of all wheels regarding steering, camber, propulsion/braking and vertical loads. Straight-line braking tests show that force allocation can be used in a real vehicle and will enhance performance and stability even at a very basic level, using few sensors with only the actual braking forces as feedback.In summary, this work has contributed to a better understanding of how the allocation of wheel forces can improve vehicle safety, performance and energy efficiency. Moreover, it has contributed to increased understanding of how vehicle motions should be modelled and simulated, and how control strategies for over-actuated vehicles can be made more suitable for implementation in future electrified vehicles.
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| 16. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
The developement of a down-scaled over-actuated vehicle equipped with autonomous corner module functionality
- 2010
-
Ingår i: FISITA Proceedings 2010, paper F2010B056.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the development of a functional down-scaled prototype of a passenger car with capability to control steering, wheel torques, wheel loads and camber individually. The adopted chassis technology is based on a modularised platform, referred to as Autonomous corner modules (ACM), which simplifies the re-use of components at the four corners of the vehicle and between different vehicles.This work gives an insight in the design of the vehicle and the selection of electrical actuators and sensors to provide all ACM functions. Since a part of the implemented chassis components do not admit to be scaled down at the same level, necessary design modifications are suggested. The problems of scaling, meaning that a down-scaled prototype cannot fully emulate a full-scaled vehicle’s all functions simultaneously, are a great disadvantage of down scaling. For example is gravity one desired parameter that is hard to physically scale down.In order to evaluate the behaviour of the down-scaled prototype, it is of high importance to establish the characteristics of the developed vehicle and its subsystems. In particular, tyre design is considered as complex. For this reason, different ideas of methods to confirm tyre characteristics are proposed.Also the paper presents the initial process of developing the prototype vehicle that is later to be used in vehicle dynamics research.
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| 17. |
- Edrén, Johannes, et al.
(författare)
-
Utilisation of optimisation solutions to control active suspension for decreased braking distance
- 2015
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:2, s. 256-273
-
Tidskriftsartikel (refereegranskat)abstract
- This work deals with how to utilise active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimisation, solutions have been found as regards how active suspension should be controlled and coordinated with friction brakes to shorten the braking distance. The results show that, for the studied vehicle, the braking distance can be shortened by more than 1 m when braking from 100 km/h. The applicability of these results is studied by investigating the approach for different vehicle speeds and actuator stroke limitations. It is shown that substantial improvements in the braking distance can also be found for lower velocities, and that the actuator strokes are an important parameter. To investigate the potential of implementing these findings in a real vehicle, a validated detailed vehicle model equipped with active struts is analysed. Simplified control laws, appropriate for on-board implementation and based on knowledge of the optimised solution, are proposed and evaluated. The results show that substantial improvements of the braking ability, and thus safety, can be made using this simplified approach. Particle model simulations have been made to explain the underlying physical mechanisms and limitations of the approach. These results provide valuable guidance on how active suspension can be used to achieve significant improvements in vehicle performance with reasonable complexity and energy consumption.
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| 18. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
Utilization of optimization solutions to control active suspension for decreased braking distance
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This work deals with how to utilize active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimization, solutions have been found to how active suspension should be controlled and coordinated with friction brakes to shorten the braking distance. The results show that, for the studied vehicle, the braking distance can be shortened by more than 1 m when braking from 100 km/h. The applicability of these results is studied by investigating the approach for different vehicle speeds and actuator stroke limitations. It is shown that substantial improvements in the braking distance can also be found for lower velocities, and that the actuator strokes are an important parameter. To investigate the potential of implementing these findings in a real vehicle, a validated detailed vehicle model equipped with active struts is analysed. Simplified control laws, appropriate for on-board implementation and based on knowledge of the optimized solution, are proposed and evaluated. The results show that substantial improvements of the braking ability, and thus safety, can be made using this simplified approach. Particle model simulations have been made to explain the underlying physics and limitations of the approach. These results provide valuable guidance on how active suspension can be used to achieve significant improvements in vehicle performance with reasonable complexity and energy consumption.
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| 19. |
- Edrén, Johannes, 1983-, et al.
(författare)
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Utilization of Vertical Loads by Optimization for Integrated Vehicle Control
- 2012
-
Ingår i: Proceedings of AVEC12, 11th Symposium on Advanced Vehicle Control, September 9-12, Seoul, Korea, 2012..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents results on how to optimally utilise vertical loading on individual wheels in order to improve vehicle performance during limit handling. Numerical optimisation has been used to find solutions on how the active suspension should be controlled and coordinated together with friction brakes and electric power assisted steering (EPAS). Firstly, it is investigated whether the brake distance can be shortened. Secondly, the performance during an evasive manoeuvre is investigated. The result shows that brake distance can be improved by at least 0.5 m and the speed through the evasive manoeuvre by roughly 1 km/h for the studied vehicle. Quick actuators is shown to give even better performance. These results provide guidance on how active suspension can be used to give significant improvements in vehicle performance.
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| 20. |
- Favre, Tristan, et al.
(författare)
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Static coupling between detached-eddy simulations and vehicle dynamic simulations of a generic road vehicle model with different rear configurations in unsteady crosswind
- 2016
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Ingår i: International Journal of Vehicle Design. - : INDERSCIENCE ENTERPRISES LTD. - 0143-3369 .- 1741-5314. ; 72:4, s. 332-353
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, aerodynamic loads of a generic car model obtained from advanced computational fluid dynamics (CFD) simulations are coupled to a vehicle dynamics model to enable the assessment of the on-road response. The influence of four rear configurations is studied. The different configurations yield large differences in yaw moments and side forces, which in turn result in considerable discrepancies in lateral displacements as well as yaw rates. From the simulations, it is seen that through balancing the location of the centre of pressure, the stiffness of the suspension bushings and the cornering stiffness of the tyres, it is possible to obtain stable vehicles in strong crosswind conditions for all four rear designs. The results show that monitoring the location of the aerodynamic centre of pressure with respect to the centre of gravity and the neutral steer point is essential for the possibility of designing stable vehicles in transient crosswind.
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| 21. |
- Harell Poznic, Pia, et al.
(författare)
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Experimental evaluation of nonlinear dynamics and coupled motions in a pantograph
- 2010
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Ingår i: Proceedings of the ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Vol 1, Pts A and B. - NEW YORK : AMER SOC MECHANICAL ENGINEERS. ; , s. 619-626
-
Konferensbidrag (refereegranskat)abstract
- Continuous electric power supply, which is transferred from the contact wire to the train through a pantograph mechanism, is a necessity for a train to function satisfactory. Since various sources of nonlinearities are present, such as friction in the pantograph suspensions and impacts in the subsystems and at the excitation, there is a possibility of nonlinear dynamic behaviour. The aim of this work is to experimentally investigate the dynamic behaviour of a commercial pantograph to verify if nonlinear behaviour and coupling effects can occur. A test rig has been built that has the ability to simulate both the horizontal and vertical excitation generated by the contact wire. Measurements have been performed for sinusoidal input signals both in horizontal and vertical directions. Harmonic and subharmonic motions as well as irregular behaviour are shown to exist in the system. The results show that the pantograph's rotational degree of freedom, friction in the suspension systems and the nonlinear stiffness play an important role for the dynamic behaviour of the system and are therefore crucial to include when creating mathematical models of the system.
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| 22. |
- Hvitfeldt, Henrik, et al.
(författare)
-
Driver gaze model for motion cueing yaw feedback optimisation
- 2023
-
Ingår i: 28th Symposium on Dynamics of Vehicles on Roads and Tracks.
-
Konferensbidrag (refereegranskat)abstract
- Driving simulators are increasingly important in vehicle development, benefiting from hardware and motion cueing algorithm (MCA) advancements. However, current state-of-the-art MCAs are optimising with regards to a vehicle fixed vestibular system, ignoring active and passive head movements during manoeuvres. Research shows that drivers actively move their heads to focus their gaze and passively stabilising it during involuntary trunk movements, resulting in significant differences between vehicle and head yaw angles. Humans isolate trunk and head movement in the range of 0.1-1.0 Hz, suggesting neck-driven gaze stabilisation. This behaviour is not accounted for in current MCAs, warranting an investigation. This study develops a driver gaze model to enhance motion cueing strategies and compares it to existing methods. Findings indicate significant discrepancies between vehicle and estimated head yaw rate in winter testing with high slip angles, and that omitting vestibular models and separating the slip angle in the yaw feedback improves the motion cueing with regards to induced head movements. Further, the results shows that there is a clear relationship between motion cueing, visual feedback, and induced driver head movement. In conclusion, driver gaze models can improve motion cueing strategies in driving simulators, and thus the study highlights the need for considering driver gaze behaviour and provides insights for tuning and optimising MCAs.
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| 23. |
- Hvitfeldt, Henrik, et al.
(författare)
-
Enhancing perception of vehicle motion by objective positioning of the longitudinal axis of rotation in driving simulators
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry is heading towards a more objective approach to vehicle testing, but subjective evaluation is still an important part of the development process. Subjective evaluation in physical testing has environmental implications and is dependent on ambient conditions. A more repeatable, faster, safer, and more cost-effective tool for subjective evaluation is to use moving base driving simulators. The motion cueing algorithms (MCA) maps the movement of the vehicle into the limited space of the simulator. The choice of reference point, i.e., where on the vehicle to sample the motion to feed to the MCA and the alignment of the axis of rotation of the simulator cabin is still an open topic. This paper investigates the choice of reference point and corresponding simulator longitudinal axis of rotation in roll using two methods. The first method uses a linearised model of the combined system of vehicle, simulator, and vestibular models. The second method, to position the cabin longitudinal axis of rotation, is based on offline optimisation. The linear model can capture important characteristics of the specific forces and rotations that are fed to the driver through the motion cueing algorithms and offers a method to objectively analyse and potentially tune the motion cueing. The analysis is further complemented with a subjective evaluation of corresponding settings. The results from the linear model, the offline optimisation and the subjective evaluation shows that a reference point at the driver’s head has a clear advantage over the full frequency range compared to a reference point in the chassis roll axis and that the positioning of the cabin longitudinal axis of rotation has a significant effect on the perceived vehicle characteristics.
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| 24. |
- Hvitfeldt, Henrik, et al.
(författare)
-
Motion cueing for winter test conditions
- 2022
-
Ingår i: IAVSD 2021. - Cham : Springer Science and Business Media Deutschland GmbH. ; , s. 888-901
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the tuning of motion cues in dynamic driving simulators for EPAS (Electronic power assisted steering) tuning in winter conditions. The study investigates the differences in frequency content of the vehicle states yaw rate and lateral acceleration between dry and winter EPAS tuning. Based on the results from this investigation, which shows an increased spectral density of low frequency content in both yaw rate and lateral acceleration, coordinated tilt is added to the motion cueing, to give the driver low frequency lateral acceleration feedback. The tilt coordination filter is tuned using offline optimisation based on logged data. The resulting MCA is evaluated objectively using a linear model of a driving simulator and subjectively through driving around a winter test track with six test drivers. The test is conducted using a pairwise comparison of two different settings, one setting without and another with added tilt coordination. Objective metrics shows reduction in lateral false cues, increased correlation between actual vehicle acceleration and simulator acceleration and an increased spectral density below 0.30 Hz. The pairwise comparison and the commentary feedback shows potential in adding tilt coordination with more drivers favouring tilt coordination, however statistical significance cannot be reached due to the low number of drivers.
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| 25. |
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| 26. |
- Hvitfeldt, Henrik, et al.
(författare)
-
Optimisation of roll axis position in a moving base driving simulator to minimise false cues
- 2021
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Ingår i: Actes (IFSTTAR). - : Driving Simulation Association. ; , s. 189-190
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a method to minimise false cues and reduce phase lag by positioning the roll axis objectively based on offline optimisation. It shows that a nonfiltered roll feedback signal could be used to reduce phase lag in the simulator and the subjective assessments indicate that the reduction of phase lag and false cues could improve the perceived fidelity of the simulator.
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| 27. |
- Hyttinen, Jukka, et al.
(författare)
-
A semi-physical thermodynamic non-stationary rolling resistance model with nonlinear viscoelasticity
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Rolling resistance dictates a large part of the energy consumption of trucks. Therefore, it is necessary to have a sound understanding of the parameters affecting rolling resistance. This article proposes a semi-physical thermodynamic tyre rolling resistance model, which captures the essential properties of rolling resistance, such as non-stationary changes due to temperature effects and the strain amplitude dependency of the viscous properties. In addition, the model includes cooling effects from the surroundings. Both tyre temperature and rolling resistance are obtained simultaneously in the simulation model for each time step. The nonlinear viscoelasticity in rubber is modelled using a Bergström-Boyce model, where the viscous creep function is scaled with temperature changes. The cooling of the tyre is considered with both convective and radiative cooling. Finally, the article explains different material parameters and their physical meaning. Additionally, examples of how the model could be used in parameter studies are presented.
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| 28. |
- Hyttinen, Jukka, et al.
(författare)
-
A semi-physical thermodynamic transient rolling resistance model with nonlinear viscoelasticity
- 2023
-
Ingår i: Mechanics of time-dependant materials. - : Springer Nature. - 1385-2000 .- 1573-2738.
-
Tidskriftsartikel (refereegranskat)abstract
- Rolling resistance dictates a large part of the energy consumption of trucks. Therefore, it is necessary to have a sound understanding of the parameters affecting rolling resistance. This article proposes a semi-physical thermodynamic tyre rolling resistance model, which captures the essential properties of rolling resistance, such as transient changes due to temperature effects and the strain-amplitude dependency of the viscous properties. In addition, the model includes cooling effects from the surroundings. Both tyre temperature and rolling resistance are obtained simultaneously in the simulation model for each time step. The nonlinear viscoelasticity in rubber is modelled using the Bergström–Boyce model, where the viscous creep function is scaled with temperature changes. The cooling of the tyre is considered with both convective and radiative cooling. Moreover, the article explains different material parameters and their physical meaning. Additionally, examples of how the model could be used in parameter studies are presented.
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| 29. |
- Hyttinen, Jukka, et al.
(författare)
-
Constitutive rubber model suitable for rolling resistance simulations of truck tyres
- 2022
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991.
-
Tidskriftsartikel (refereegranskat)abstract
- Tyres are a vital vehicle component forming an interface between a vehicle and the road, enabling the generation of braking, steering and traction forces. However, they also generate rolling resistance which researchers have tried to minimise through the years for environmental and economic reasons. Despite numerous attempts to model rolling resistance of tyres there still does not seem to exist a simple, flexible and accepted way of modelling rolling resistance in the time domain as well as parametrising models in an easy and accessible way. This study explores a simple and intuitive way of parametrising a hyperviscoplastic parallel rheological framework. In the experimental part of this study, rubber samples with various amounts of carbon black filler are extracted from a truck tyre section and tested using dynamic mechanical analysis. The test data was used to parametrise the material model. The model consists of Mooney-Rivlin hyperelasticity, 40 Prony elements and 8 perfectly plastic elements with Ogden hyperelasticity. The paper introduces a method to obtain a large number of parameters using only six tuneable parameters, which simplifies the tuning of the model drastically. The parametrised model is suitable for tyre rolling resistance simulations with frequency and strain amplitude dependency of the storage and loss modulus. A wide range of strain amplitudes and frequencies can be covered with the proposed method and it is possible to achieve a good fit for the storage and loss modulus values with the benefit of only a few tuneable parameters. Additional Prony or plastic networks do not increase the amount of tuneable parameters. Moreover, the method can be used to parametrise the material using manual iterations which is generally not possible for a parallel rheological framework with such a large amount of parameters.
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| 30. |
- Hyttinen, Jukka, et al.
(författare)
-
Development and analysis of an on-road torque measurement device for trucks
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Rolling resistance and aerodynamic losses cause a significant part of a truck's energy consumption. Therefore there is an interest from both vehicle manufacturers and regulators to measure these losses to understand, quantify and reduce the energy consumption of vehicles. On-road measurements are particularly interesting because it enables testing in various ambient conditions and road surfaces with vehicles in service.Objective: Common driving loss measurement devices require unique instrumented measurement wheels, which hinders effective measurements of multiple tyre sets or measurements of vehicles in service. For this purpose, the objective is to develop a novel load-sensing device for measuring braking or driving torque.Methods: The strength of the measurement device is calculated using finite element methods, and the output signal is simulated using virtual strain gauge simulations. In addition to the signal simulation, the device is calibrated using a torsional test rig.Results: The simulation results confirm that the device fulfils the strength requirements and is able to resolve low torque levels. The output signal is simulated for the novel cascaded multi-Wheatstone bridge using the strains extracted from the finite element analysis. The simulations and measurements show that the measurement signal is linear and not sensitive to other load directions. The device is tested on a truck, and the effort of mounting the device is comparable to a regular tyre change.Conclusions: A novel driving loss measurement device design is presented with an innovative positioning of strain gauges decoupling the parasitic loads from the driving loss measurements. The design allows on-road testing using conventional wheels without requiring special measurement wheels or instrumentation of drive shafts, enabling more affordable and accurate measurements.
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| 31. |
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| 32. |
- Hyttinen, Jukka, et al.
(författare)
-
Do heat-insulated wheelhouses affect truck tyre temperature and rolling resistance?
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Due to legislations introduced to prevent global warming, vehicle manufacturers must find new ways to reduce CO2 emissions. This paper explores a way to reduce rolling resistance by heat insulating and covering a truck's wheelhouse. The rolling resistance of a truck tyre was measured at +5 °C ambient temperature for consecutive speed steps in a climate wind tunnel with and without heat insulation. The study showed that by encapsulating and insulating the wheelhouse, already generated strain-induced heat could be kept in the tyre, consequently producing a lower rolling resistance. During the tests, the tyre shoulder temperature was monitored along with the tyre pressure. When the wheelhouses were encapsulated, a significant reduction in rolling resistance and an increase in tyre pressure and temperature were measured at all evaluated speed levels.
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| 33. |
- Hyttinen, Jukka, et al.
(författare)
-
Effect of Ambient and Tyre Temperature on Truck Tyre Rolling Resistance
- 2022
-
Ingår i: International Journal of Automotive Technology. - : Springer Nature. - 1229-9138 .- 1976-3832.
-
Tidskriftsartikel (refereegranskat)abstract
- Rolling resistance is consuming a large portion of the generated powertrain torque and thus have a substantial effect on truck energy consumption and greenhouse gas emissions. EU labelling of tyres mandates the manufacturers to measure rolling resistance at +25 °C ambient temperature after stabilised rolling resistance has been established. This is a convenient way of comparing rolling resistance but disregards aspects such as transient rolling resistance and influence of the ambient temperature. For many purposes, such as dimensioning batteries for electric vehicles, this value is not representative enough to give a good understanding of the rolling resistance. In this article, the rolling resistance of a truck tyre was measured at different ambient temperatures (-30 to +25 °C) in a climate wind tunnel and a considerable tyre and ambient temperature dependency on rolling resistance was found. The investigation shows that the temperature inside the tyre shoulder has a good correlation with rolling resistance. Measurements with spraying water on tyres were conducted showing a considerable increase in rolling resistance due to higher cooling effect. Driving range simulations of a long haulage battery-electric truck have been conducted with temperature-dependent rolling and aerodynamic resistance, showing a significant decrease in driving range at decreasing temperature.
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| 34. |
- Hyttinen, Jukka, et al.
(författare)
-
Estimating Tire Pressure Based on Different Tire Temperature Measurement Points
- 2024
-
Ingår i: Automotive Technical Papers, WONLYAUTO 2024. - : SAE International.
-
Konferensbidrag (refereegranskat)abstract
- Knowing the tire pressure during driving is essential since it affects multiple tire properties such as rolling resistance, uneven wear, and how prone the tire is to tire bursts. Tire temperature and cavity pressure are closely tied to each other; a change in tire temperature will cause an alteration in tire cavity pressure. This article gives insights into which tire temperature measurement position is representative enough to estimate pressure changes inside the tire, and whether the pressure changes can be assumed to be nearly isochoric. Climate wind tunnel and road measurements were conducted where tire pressure and temperature at the tire inner liner, the tire shoulder, and the tread surface were monitored. The measurements show that tires do not have a uniform temperature distribution. The ideal gas law is used to estimate the tire pressure from the measured temperatures. The results indicate that of the compared temperature points, the inner liner temperature is the most accurate for estimating tire pressure changes (average error 0.63%), and the pressure changes during driving are nearly isochoric. This conclusion can be drawn because the ratio between inner liner temperature and tire pressure is nearly constant, and the pressure can be simulated well using the isochoric gas law.
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| 35. |
- Hyttinen, Jukka, et al.
(författare)
-
Estimating tyre pressure based on different tyre temperature measurement points
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Knowing the tyre pressure during driving is essential since it affects multiple tyre properties such as rolling resistance, uneven wear, and how prone the tyre is to tyre bursts. Tyre temperature and cavity pressure are closely tied to each other; a change in tyre temperature will cause an alteration in tyre cavity pressure. This article gives insights into which tyre temperature measurement position is representative enough to estimate pressure changes inside the tyre, and whether the pressure changes can be assumed to be nearly isochoric. Climate wind tunnel and road measurements were conducted where tyre pressure and temperature at the tyre inner-liner, the tyre shoulder, and the tread surface were monitored. The measurements show that tyres do not have a uniform temperature distribution. The ideal gas law is used to estimate the tyre pressure from the measured temperatures. The results indicate that of the compared temperature points, the inner-liner temperature is the most accurate for estimating tyre pressure changes (average error 0.63 %), and the pressure changes during driving are nearly isochoric. This conclusion can be drawn because the ratio between inner-liner temperature and tyre pressure is nearly constant, and the pressure can be simulated well using the isochoric gas law.
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| 36. |
- Hyttinen, Jukka, et al.
(författare)
-
Finite element truck tyre rolling resistance simulation using a viscoplastic parallel rheological framework
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A vehicle’s energy consumption is significantly affected by a resisting force created by the tyres. This resisting force, called rolling resistance, is an essential factor in the energy consumption of trucks, not only in terms of operational costs but also in terms of the range of electric trucks or other vehicles that run on sustainable energy sources. This article presents a method for calculating truck tyre rolling resistance in finite element software (MSC Marc). With the help of X-ray, 3D, and CT scanning, a representative tyre model is obtained. A viscoplastic model with separate viscoelastic and plastic parts is used to model rubber. The rolling resistance coefficient is obtained using two different methods: calculating it from the nodal contact forces at the contact patch and from contact body forces. Both methods produced comparable results, showing that the constitutive model produces realistic simulation results and, therefore, is suitable for rolling resistance simulations.
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| 37. |
- Hyttinen, Jukka
(författare)
-
Modelling and experimental testing of truck tyre rolling resistance
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Truck transport offers a versatile way to ship goods in regional, long haulage and urban applications. However, the heavy truck sector accounts for 6 % of total greenhouse gas emissions in the European Union. Therefore, there is a need for a substantial reduction of these emissions to secure the sustainability of Earth for future generations. A key parameter to be considered is rolling resistance, which is the source of approximately half of truck energy consumption.This thesis aims to provide knowledge and insights about rolling resistance simulations and testing, as well as contribute to a better understanding of parameters affecting rolling resistance. Tests in a climate wind tunnel and on the road were conducted at various speeds and a wide range of ambient temperatures (-30 to +25 °C), providing measurement results that are generally unavailable. The measurements show a considerable increase in the stabilised and non-stationary rolling resistance with lower tyre and ambient temperatures. Furthermore, a way to reduce tyre cooling is suggested in order to increase tyre temperature and thereby reduce rolling resistance. Another key result of this thesis is the design of an on-road driving loss device, which enables quick and convenient validation of energy consumption simulations by retaining the standard interface between the rim and axle while measuring required driving torque during on-road testing. Three different simulation models of varying complexity are proposed to simulate rolling resistance: (I) a phenomenological real-time capable rolling resistance estimation model that utilises time-temperature-superposition and a variable thermal inertia temperature model; (II) a semi-physical thermodynamic tyre rolling resistance model with a temperature-dependent nonlinear viscoelastic model that can be used in different parameter studies, such as to analyse the effect of tyre cooling on tyre temperature and rolling resistance; and (III) a finite element simulation model with a hyperviscoplastic PRF rubber model for detailed structural analyses. Furthermore, a convenient method for parametrising a complicated PRF rubber model utilising reduced material parameters was developed and parametrised against measurement data. The reduced material constants simplify the parametrisation, allowing the model to be parametrised with only manual iterations, which is generally not possible. Electric vehicles, such as trucks, passenger cars and electrically assisted bicycles, suffer from a reduced driving range at cold temperatures. Increasing the understanding of the influence of rolling resistance on range aspects can help accelerate the adoption of battery-electric trucks and other vehicles that use sustainable energy sources. Therefore, a driving range simulation of a battery-electric truck was conducted where the truck tyre rolling and aerodynamic resistance were varied with ambient temperature, showing a considerable decrease in driving range at cold temperatures. The experiments, simulations and the developed measurement device contribute to an increased understanding of rolling resistance and the factors affecting it. These insights are an essential part of developing future resource-efficient vehicles and transport systems where, e.g., transport flow can be optimised by taking into account rolling resistance, aerodynamic resistance and other essential factors.
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| 38. |
- Hyttinen, Jukka, et al.
(författare)
-
Simulation of a truck tyre using a viscoplastic constitutive rubber model
- 2022
-
Ingår i: IAVSD 2021. - Cham : Springer Science and Business Media Deutschland GmbH. ; , s. 1005-1014
-
Konferensbidrag (refereegranskat)abstract
- Tyres are a vital component for handling and load carrying while also contributing to the operating cost and environmental impact. The innovations in tyre design are driven by the need to reduce greenhouse gases and to make a better compromise between conflicting tyre properties. To accurately simulate tyres and to make these compromises a representative rubber model needs to be incorporated with strain amplitude dependency for the storage and loss modulus (the Fletcher-Gent effect). Prony series is a commonly used viscoelastic model in tyre simulations but it does not take into account the Fletcher-Gent effect and e.g. possible nonlinearities due to axle load variations are not feasible to simulate. The Fletcher-Gent effect can be modelled using parallel rheological framework (PRF), which can consist of any combination of parallel material models. Nonlinear viscoelastic models have strain amplitude dependency for the storage modulus but single nonlinear parameters lose their clarity in a PRF. Another approach is to combine a linear viscoelastic model with plasticity as is done in this article. Here, an FE truck tyre is developed and used with a viscoplastic PRF model that utilises Prony series with Mooney-Rivlin hyperelasticity and multiple plastic networks. The benefit of this combination is that the strain amplitude and frequency dependency of the storage and loss modulus are separated, which makes parameter studies simpler. The article shows that an FE truck tyre with a viscoplastic PRF model can be used in different simulations to study e.g. steady-state rolling, footprint, vertical stiffness and longitudinal tyre forces.
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| 39. |
- Hyttinen, Jukka
(författare)
-
Truck tyre rolling resistance : Experimental testing and constitutive modelling of tyres
- 2022
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Global warming sets a high demand to reduce the CO2 emissions of vehicles. In the European Union heavy-duty road transports account for 6 % of the total greenhouse gases and one of the main factors affecting these emissions is related to the rolling resistance of tyres. The optimal usage of tyres is an important part of solving these challenges, thereby it is important to understand the parameters affecting rolling resistance and the different compromises coupled to them. These compromises could be analysed using computational and experimental methods. To set out the groundwork necessary to minimise the energy consumption of trucks and assess the different parameters affecting tyre behaviour, the following studies have been conducted during this thesis. A framework to model and parametrise truck tyre rubber has been developed for finite element simulations. The presented parallel rheological material model utilises Mooney-Rivlin hyperelasticity, Prony series viscoelasticity, and perfectly plastic networks. A method to reduce tuneable parameters of the model, which significantly simplifies possible parameter studies, is presented. The model has been parametrised using test data from dynamic mechanical analysis of samples from a long haulage heavy truck tyre, and shows a good agreement with the test data. To test the suitability of the modelling technique for tyre simulations, the constitutive model is used in various tyre simulations using the arbitrary Lagrangian-Eulerian method. The material modelling technique is shown to work for static force-deflection as well as dynamic simulations estimating longitudinal force build-up with varying slip levels. Additionally, the modelling technique captures the uneven contact pressure in steady-state rolling, which indicates that the model could also be used in rolling resistance simulations. To study the change of ambient temperature on rolling resistance using experimental methods, a climate wind tunnel is used where the rolling resistance is quantified using a measurement drum. Tests were conducted between -30 °C and +25 °C, and a considerable ambient temperature dependency on rolling resistance was found. Moreover, temperature measurement inside a tyre shoulder is a good indicator for rolling resistance in a broad range of ambient temperatures. Finally, battery-electric long haulage truck driving range calculations are also conducted with varying rolling resistance and air density at different temperatures, showing a significant decrease of driving range with decreasing ambient temperature.
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| 40. |
- Hyttinen, Jukka, et al.
(författare)
-
Truck tyre transient rolling resistance and temperature at varying vehicle velocities : Measurements and simulations
- 2023
-
Ingår i: Polymer testing. - : Elsevier BV. - 0142-9418 .- 1873-2348. ; 122
-
Tidskriftsartikel (refereegranskat)abstract
- Rolling resistance is causing a significant part of the energy consumption in truck applications, especially at lowspeed levels. To be able to better estimate the energy consumption or remaining driving range, the truck tyre rolling resistance must be understood well. Temperature is a vital parameter for rolling resistance estimations. This article shows truck tyre rolling resistance and temperature measurements in a climate wind tunnel and simulations of tyre temperature and rolling resistance. During the climate wind tunnel tests, tyre temperature at the shoulder and tread was measured. In addition, on-road driving was conducted with inner-liner infrared temperature measurements. Tyre temperature simulations were conducted using a thermal tyre model with speed-variable thermal inertia. The comparison of tyre temperature simulations with measured inner-liner and shoulder temperatures showed good agreement with the test data. The rolling resistance was simulated using the principle of time-temperature superposition, and a master curve for rolling resistance and a curve for tyre temperature shift were constructed. These curves were used to simulate rolling resistance at a wide range of speed levels with good agreement to the experimental results. The investigation showed that the tyre shoulder temperature is a better indicator of rolling resistance than infrared measurements from the tyre tread.
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| 41. |
- Jerrelind, Jenny, et al.
(författare)
-
A global control strategy for efficient control of a Braille impact hammer
- 2006
-
Ingår i: Journal of Vibration and Acoustics-Transactions of the ASME. - : American Society of Mechanical Engineers. - 1048-9002 .- 1528-8927. ; 128:2, s. 184-189
-
Tidskriftsartikel (refereegranskat)abstract
- A combined control scheme relying on feedback-based local control in the vicinity of periodic system responses and global control based on a coarse-grained approximation to the nonlinear dynamics is developed to achieve a desirable dynamical behavior of a Braille printer impact hammer The proposed control methodology introduces discrete changes in the position of a system discontinuity at opportune moments during the hammer motion while the hammer is away from the discontinuity, thereby exploiting the recurrent contacts with the discontinuity to achieve the desired changes in the transient dynamics. It is argued that, as the changes in the position of the discontinuity affect the motion only indirectly through changes in the timing and state at the subsequent contact, the control actuation can be applied over an interval of time during the free-flight motion as long as it is completed prior to contact. A forced, piecewise smooth, single-degree-of freedom model of a Braille impact hammer is used to illustrate the methodology and to yield representative numerical results.
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| 42. |
- Jerrelind, Jenny, et al.
(författare)
-
Braille printer Dynamics
- 1999
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Ingår i: Proceedings of the ASME Design Engineering Technical Conferences.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 43. |
- Jerrelind, Jenny, 1974-, et al.
(författare)
-
Contributions of vehicle dynamics to the energy efficient operation of road and rail vehicles
- 2021
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 59:7, s. 1114-1147
-
Tidskriftsartikel (refereegranskat)abstract
- This review addresses efforts made within the field of vehicle dynamics to contribute to the energy efficient operation of road and rail vehicles. Selected investigations of the research community to develop technology solutions to reduce energy consumption are presented. The study explores the impact and potential of relatively mature technologies such as regenerative braking, but also recent research directions that are seeking to develop solutions such as regenerative suspensions, a concept common to both transport modes. Specifically for road vehicles, the study includes rear wheel steering, camber control and torque vectoring, and for rail vehicles active steering and light-weighting. Operationally, there would appear to be great potential for rail vehicles in the wider adoption of connected driver advisory systems, and automatic train control systems, including the application of machine learning techniques to optimise train speed trajectories across a route. Similarly, for road vehicles, predictive and cooperative eco-driving strategies show potential for significant energy savings for connected autonomous vehicles.
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| 44. |
- Jerrelind, Jenny, 1974-
(författare)
-
Design and Control of Products Including Parts with Impacts
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today's product development process should be rapid andcost-efficient, and should result in innovative and reliableproducts. A crucial factor is the dynamic behaviour of theproduct. This thesis focuses on theoretical, numerical andexperimental approaches to achieve a comprehensiveunderstanding of dynamical phenomena occurring in nonlinearproducts, especially in products with parts that includeimpacts. The aim is to show the usefulness of nonlineartheories to better understand and optimise the dynamicbehaviour of products and thereby account for nonlinearphenomena already in the product development process. This is achieved through an investigation of researchefforts in the field of nonlinear dynamics; identification ofimportant research directions; a study on the effect ofcouplings between nonlinear parts; a detailed study on thedynamic behaviour of a product component; investigations oflow-cost strategies for controlling the dynamics of a nonlinearsystem; and the design and implementation of experimentalset-ups of two studied products. The investigation of research efforts shows that nonlinearparts are frequently included in products. Most common areparts that are nonlinear due to impacts and friction. Twoimportant areas are identified; to study coupling effectsbetween nonlinear subsystems and to study how nonlinearanalysis can be used to improve existing designs. Considering the studied products; a pantograph on a trainand a Braille printer, it can be concluded that thecharacteristics of a part can largely affect the dynamicbehaviour of the product. Typical nonlinear behaviour, such ascoexisting solutions and irregular motions, do occur. Theanalysis of the pan- tograph motion shows important aspects toconsider in the modelling process; coupling effects. In thecase of the Braille printer it is shown possible to create alow-cost control, by taking advantage of an existingdiscontinuity, to achieve a desired motion. Altogether, this work contributes to improved understandingof the be- haviour of nonlinear parts in products, especiallythose including impacts, pro- viding greater knowledge aboutaspects to consider in the design process. Keywords:Nonlinear Dynamics, Impacts, Discontinuities,Subsystems, Chaos, Irregular Behaviour, Printer Dynamics,Suspensions, Coupled Systems, Control.
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| 45. |
- Jerrelind, Jenny, et al.
(författare)
-
Effects of non-linear wheel suspension bushing on vehicle response
- 2012
-
Ingår i: Proceedings of the ASME Design Engineering Technical Conferences And Computers And Information In Engineering Conference, Vol 6. - : ASME Press. - 9780791845059 ; , s. 615-622
-
Konferensbidrag (refereegranskat)abstract
- This work presents an analysis of the effects of non-linear characteristics of a top mount bushing in the wheel suspension of a vehicle when evaluating vehicle characteristics such as comfort and handling. The investigation is performed by comparing simulation results from a quarter car model when using a non-linear bushing model and an approximated linear bushing model. It is revealed when analysing the results that there are differences in the response when comparing measures such as sprung mass acceleration, rattle space ratio and tyre-ground contact force. The conclusion is that the more detailed bushing model mainly affects the acceleration levels especially at high frequencies where the linear model underestimates the acceleration. The rattle space ratio and tyre-ground contact force are also affected but not to the same extent.
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| 46. |
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| 47. |
- Jerrelind, Jenny, et al.
(författare)
-
Exploring active camber to enhance vehicle performance and safety
- 2013
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study is to evaluate optimal active camber strategies for improvement of vehicle performance and safety during limit handling. Numerical optimisation is used to find solutions on how the active camber should be controlled and coordinated in cooperation with individual braking and front axle steering. Based on the characteristics of a multi-line brush tyre model, a Simple Magic Formula description is developed where camber dependency, load sensitivity and first order speed dependent relaxation dynamics are included. The vehicle is analysed during an evasive manoeuvre when the vehicle is running at the limit. It is evident from the results that active camber control can improve safety and performance during an avoidance manoeuvre.
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| 48. |
- Jerrelind, Jenny, et al.
(författare)
-
Low-Cost Control of Impact Hammer Performance
- 2003
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Ingår i: ASME Conference Proceedings. - : ASME Press. ; , s. 1547-1554
-
Konferensbidrag (refereegranskat)abstract
- This paper considers the dependence of the performance of a Braille printer impact hammer on system parameters, specifically the lag time between subsequent current pulses and the location of a back stop constraining the oscillations of the hammer core. Here, the goal is to improve the printer speed while maintaining readability of the Braille type and preventing tears in the paper. Based on observations of the limit sets for the hammer-core dynamics, a low-cost feedback control algorithm is proposed for affecting the stability of otherwise unstable periodic oscillations with more desirable operating characteristics.
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| 49. |
- Jerrelind, Jenny, et al.
(författare)
-
Nonlinear dynamic behaviour of coupled suspension systems
- 2003
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Ingår i: Meccanica (Milano. Print). - : Springer. - 0025-6455 .- 1572-9648. ; 38:1, s. 43-59
-
Tidskriftsartikel (refereegranskat)abstract
- A two degrees of freedom model of two coupled suspension systems characterised by piecewise linear stiffness has been studied. The system, representing a pantograph current collector head, is shown to be sensitive to changes in excitation and system parameters, possessing chaotic, periodic and quasiperiodic behaviour. The coupled system has a more irregular behaviour with larger motions than the uncoupled suspension system, indicating that the response from the uncoupled suspension system cannot be used as a worst case measure. Since small changes in system parameters and excitation affect the results drastically then wear and mounting as well as actual operating conditions are crucial factors for the system behaviour.
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| 50. |
- Jerrelind, Jenny, et al.
(författare)
-
Nonlinear dynamics of parts in engineering systems
- 2000
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Ingår i: Chaos, Solitons & Fractals. - : Elsevier. - 0960-0779 .- 1873-2887. ; 11:15, s. 2413-2428
-
Tidskriftsartikel (refereegranskat)abstract
- By definition, chaotic vibrations arise from nonlinear deterministic physical systems or non-random differential or difference equations. In numerous engineering systems there exist nonlinearities which might affect the dynamic behaviour of the system. The objectives in this work are to summarise previous work on nonlinear dynamics of engineering parts and products and to investigate if research on how nonlinear parts can effect the total behaviour of the products have been performed. It is found that common nonlinear parts are machine elements such as gears, bearings, brakes and suspension systems. The most studied part in a product is of impact hammer type. The products are ordinary products, from searing machines, drilling machines and printers to railway vehicles. In order to be able to design reliable products the methodology should be further developed to enable use by engineers. One can conclude that the effect of nonlinear parts on the total system behaviour is still a fairly uninvestigated area.
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