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Viewing 241 to 270 of 11068
2017-03-28
Journal Article
2017-01-1563
Abhijeet Behera, Murugan Sivalingam
Abstract Two and three wheeler vehicles are largely used in many developing and under developing countries because of their lower cost, better fuel economy and easy handling. Although, the construction of them is simpler than the four wheeler vehicle, they pose some problems related to instability. Wobbling is the main cause of instabilities in two wheeler and three wheeler vehicles. In this study, a mathematical model was proposed and developed to determine wobble instability of a two wheeler. Nonlinear equations were formulated by using kinematics and the D’Alembert’s principle with the help of multi body formalism. The non-linear equations found in the study were linearized with respect to rectilinear and upright motion, considering no rolling. It led to formation of matrix. The real part of the Eigen value of the matrix was found to be negative, implication of whose was an asymptotic stable motion.
2017-03-28
Technical Paper
2017-01-1590
Jyotishman Ghosh, Stéphane Foulard, Rafael Fietzek
Abstract A method for estimating the vehicle mass in real time is presented. Traditional mass estimation methods suffer due a lack of knowledge of the vehicle parameters, the road surface conditions and most importantly the effect of the vehicle transmission. To resolve these issues, a method independent of a vehicle model is utilized in conjunction with a drivetrain output torque observer to obtain the estimate of the vehicle mass. Simulations and experimental track tests indicate that the method is able to accurately estimate the vehicle mass with a relatively fast rate of convergence compared to traditional methods.
2017-03-28
Technical Paper
2017-01-1555
Mirosław Jan Gidlewski, Krystof JANKOWSKI, Andrzej MUSZYŃSKI, Dariusz ŻARDECKI
Abstract Lane change automation appears to be a fundamental problem of vehicle automated control, especially when the vehicle is driven at high speed. Selected relevant parts of the recent research project are reported in this paper, including literature review, the developed models and control systems, as well as crucial simulation results. In the project, two original models describing the dynamics of the controlled motion of the vehicle were used, verified during the road tests and in the laboratory environment. The first model - fully developed (multi-body, 3D, nonlinear) - was used in simulations as a virtual plant to be controlled. The second model - a simplified reference model of the lateral dynamics of the vehicle (single-body, 2D, linearized) - formed the basis for theoretical analysis, including the synthesis of the algorithm for automatic control. That algorithm was based on the optimal control theory.
2017-03-28
Technical Paper
2017-01-1483
Jia Mi, Lin Xu, Sijing Guo, Mohamed A. A. Abdelkareem, Lingshuai Meng
Abstract Systematic research on dynamic model, simulation analyses, prototype production and bench tests have been carried out in recent years on the most popular energy-harvesting shock absorbers-the mechanical motion rectifier (MMR), and the hydraulic-electromagnetic energy-regenerative shock absorber (HESA). This paper presents a novel application of the HESA into bogie system of railway vehicles. In order to study the differences of suspension performance and energy harvesting property between first suspension system and second suspension system of the application, simulation models are built in AMESim to make comparison studies on the different department suspensions caused by the nonlinear damping behaviors of the HESA. The simulation results show that the system can effectively reduce the impact between wheel and rail tracks, while maintaining good potential to recycle vibratory energy.
2017-03-28
Technical Paper
2017-01-1591
Haotian Cao, Xiaolin Song, Zhi Huang
Abstract Generally speaking, lateral steering control method which ensures a good performance in tracking quality and handle quality simultaneously for autonomous vehicle is a changeling task. In order to keep the vehicle to stay safe when facing with severe situations such as an emergency lane change, a switched MPC lateral steering controller, which is on the basis of the stability feature of the vehicle, is presented in this paper. First, a MPC steering controller based on the 3DOF nonlinear vehicle model is derived, a comparative study of different vehicle models for MPC prediction are made. It proves that the presented MPC controller based on 3DOF nonlinear vehicle model possesses an advantage of balancing the conflicts between the tracking quality and handling quality of the vehicle.
2017-03-28
Technical Paper
2017-01-0347
Yat Sheng Kong, Dieter Schramm, M. Zaidi Omar, Sallehuddin Mohd. Haris, Shahrum Abdullah
This paper presents the study of a relationship between objective vertical vibration and coil spring fatigue life under different road excitation to shorten suspension design process. Current development processes of vehicle suspension systems consist of many different stages of analysis and time consuming. Through this vertical vibration and durability characterisation, the vehicle ISO weighted vertical accelerations were used to describe fatigue life of coil spring. Strain signals from various roads were measured using a data acquisition and then converted into acceleration signal. The acceleration signals were then used as input to multibody suspension model for forces time history on spring and acceleration signal of sprung mass extraction. The acceleration signals were then processed for ISO weighted indexes while the force time history was used for coil spring fatigue life prediction respectively.
2017-03-28
Technical Paper
2017-01-0066
Shogo Nakao, Akihiko Hyodo, Masaki Itabashi, Tomio Sakashita, Shingo Obara, Tetsuya Uno, Yasuo Sugure, Yoshinobu Fukano, Mitsuo Sasaki, Yoshihiro Miyazaki
This paper presents the “Virtual Failure Mode and Effects Analysis (vFMEA)” system, which is a high-fidelity electrical-failure-simulation platform, and applies it to the software verification of an electric power steering (EPS) system. The vFMEA system enables engineers to dynamically inject a drift fault into a circuit model of the electronic control unit (ECU) of an EPS system, to analyze system-level failure effects, and to verify software-implemented safety mechanisms, which consequently reduces both cost and time of development. The vFMEA system can verify test cases that cannot be verified using an actual ECU and can improve test coverage as well. It consists of a cycle-accurate microcontroller model with mass-production software implemented in binary format, analog and digital circuit models, mechanical models, and a state-triggered fault-injection mechanism.
2017-03-28
Technical Paper
2017-01-0056
Naveen Mohan, Martin Törngren, Sagar Behere
Abstract With the advent of ISO 26262 there is an increased emphasis on top-down design in the automotive industry. While the standard delivers a best practice framework and a reference safety lifecycle, it lacks detailed requirements for its various constituent phases. The lack of guidance becomes especially evident for the reuse of legacy components and subsystems, the most common scenario in the cost-sensitive automotive domain, leaving vehicle architects and safety engineers to rely on experience without methodological support for their decisions. This poses particular challenges in the industry which is currently undergoing many significant changes due to new features like connectivity, servitization, electrification and automation. In this paper we focus on automated driving where multiple subsystems, both new and legacy, need to coordinate to realize a safety-critical function.
2017-03-28
Technical Paper
2017-01-0239
Seth Bryan, Maria Guido, David Ostrowski, N. Khalid Ahmed
Abstract It is desirable to find methods to increase electric vehicle (EV) driving range and reduce performance variability of Plug-in Hybrid Electric Vehicles (PHEV). One strategy to improve EV range is to increase the charge power limit of the traction battery, which allows for more brake energy recovery. This paper applies Big Data technology to investigate how increasing the charge power limit could affect EV range in real world usage with respect to driving behavior. Big Data Drive (BDD) data collected from Ford employee vehicles in Michigan was analyzed to assess the impact of regenerative braking power on EV range. My Ford Mobile (MFM) data was also leveraged to find correlation to drivers nationwide based on brake score statistics. Estimated results show incremental improvements in EV range from increased charge power levels. Subsequently, this methodology and process could be applied to make future design decisions based on the dynamic nature of driving habits.
2017-03-28
Technical Paper
2017-01-1537
Ananya Bhardwaj
Abstract Improving brake cooling has commanded substantial research in the automotive sector, as safety remains paramount in vehicles of which brakes are a crucial component. To prevent problems like brake fade and brake judder, heat dissipation should be maximized from the brakes to limit increasing temperatures. This research is a CFD investigation into the impact of existing wheel center designs on brake cooling through increased cross flow through the wheel. The new study brings together the complete wheel and disc geometries in a single CFD study and directly measures the effect on brake cooling, by implementing more accurately modeled boundary conditions like moving ground to replicate real conditions correctly. It also quantifies the improvement in the cooling rate of the brake disc with a change in wheel design, unlike previous studies.
2017-03-28
Technical Paper
2017-01-1481
Kyung-bok Lee, Sanghyuk Lee, Namyoung Kim, Bong Soo Kim, Tae soo Chi, Do young Kim
Abstract Conventional EPS (Electric Power Steering) systems are operated by one type of steering tuning map set by steering test drivers before being released to customers. That is, the steering efforts can't change in many different driving conditions such as road conditions (low mu, high mu and unpaved roads) or some specific driving conditions (sudden stopping, entering into EPS failure modes and full accelerating). Those conditions can't give drivers consistent steering efforts. This paper approached the new concept technology detecting those conditions by using vehicle and EPS sensors such as tire wheel speeds, vehicle speed, steering angle, steering torque, steering speed and so on. After detecting those conditions and judging what the best steering efforts for safe vehicle driving are, EPS systems automatically can be changed with the steering friction level and selection of steering optimized mapping on several conditions.
2017-03-28
Journal Article
2017-01-1482
Jens Dornhege, Simon Nolden, Martin Mayer
Abstract The layout of a vehicle steering system has to resolve a compromise. While it is important for lateral vehicle control to feel steering torque feedback of lateral tire to ground interaction, disturbing forces shall not be present in the feedback steering torque. These disturbing forces result from road irregularities, wheel rotor imbalance, suspension asymmetry caused by production tolerances, wear or impacts, and additional vehicle internal forces, e.g. the steered wheels also driven by the engine or braked. In general these disturbances are reduced by an optimization of the suspension geometry to decrease the impact of the unintended forces on the steering system. The remaining disturbance is controlled to an acceptable level via force feedback sensitivity calibration of the steering system, what in return influences the intended driver sensitivity to feel lateral tire forces.
2017-03-28
Technical Paper
2017-01-1490
Silvia Faria Iombriller
Abstract The air suspension development and its applications have becoming increasingly relevant for commercial vehicles to provide dynamic ride comfort to driver and reduce the load impact onto driver and or cargo. This paper shows the analysis and application of an air suspension system for commercial tractor vehicles and its dynamic influence. A special focus was given to pneumatic actuation system, responsible for leveling and control of suspension´s stiffness under different conditions of usage, laden and unladed. The project was conducted starting with the vehicle dynamic performance analysis, evaluating the pneumatic suspension circuit modifications in order to obtain vehicle dynamic behavior improvement, ensuring directional stability under different maneuvering conditions.
2017-03-28
Technical Paper
2017-01-1494
Weinan Tao, Bingzhao Gao, Hongqing Chu, Mengjian Tian, Hong Chen
Abstract The steer-by-wire system has been widely studied due to many advantages such as good controllability. In the system, the steering column is cancelled and the driver can't feel the feedback torque (also called steering feeling) coming from the ground. Therefore a steering feeling feedback system is needed. In this paper, we propose a simple method to calculate desired feedback torque based on a nonlinear 2DOF vehicle model. The vehicle model contains the nonlinearity of tire. So that the proposed method is also appropriate for big acceleration conditions. Besides that, the properties of steering system such as friction and stiffness are also taken into consideration. As for conventional steering system, driver can only feel part of the feedback torque due to the power assist system. In order to provide steering feeling similar to conventional steering system, a weighting function is proposed to compensate the influence of power assist system.
2017-03-28
Technical Paper
2017-01-1488
Srinivas Kurna, Ruchik Tank, Riddhish Pathak
Abstract The job of a suspension system is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to act as a cushioning device ensuring the comfort of the driver & passengers. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. Almost all heavy duty vehicles use inverted type suspension system which is also called as bogie type suspension system. The design of this type of suspension is a complex and difficult science which has evolved over many years. It was recognized very early in the development of suspensions that the interface between vehicle body and wheel needed some sort of cushioning system to reduce the vibration felt as the vehicle moved along. This was already part of road coach design and took the form of leaf (laminated) steel springs mounted on the axles, upon which the vehicle body rested.
2017-03-28
Technical Paper
2017-01-1225
Jayaraman Krishnasamy, Martin Hosek
Abstract An advanced electric motor with hybrid-field topology has been developed for automotive traction applications. Departing from the conventional radial- and axial-field designs, the hybrid-field motor features three-dimensional magnetic flux paths, which are enabled by a novel isotropic soft magnetic material produced by a unique additive-manufacturing process based on spray forming. The motor is expected to offer an unprecedented combination of high power output, compact size, low weight and energy efficiency, achieving more than two times higher power density than state-of-the-art high-performance traction motors.
2017-03-28
Technical Paper
2017-01-1556
Jianbo Lu, Li Xu, Daniel Eisele, Stephen Samuel, Matthew Rupp, Levasseur Tellis
Abstract This paper presents an advanced yaw stability control system that uses a sensor set including an inertial measurement unit to sense the 6 degrees-of-freedom motions of a vehicle. The full degree of the inertial measurement unit improves and enhances the vehicle motion state estimation over the one in the traditional electronic stability controls. The addition of vehicle state estimation leads to the performance refinement of vehicle stability control that can improve performance in certain situations. The paper provides both detailed system description and test results showing the effectiveness of the system.
2017-03-28
Journal Article
2017-01-1558
Jose Velazquez Alcantar, Francis Assadian, Ming Kuang
Abstract Hybrid Electric Vehicles (HEV) offer improved fuel efficiency compared to their conventional counterparts at the expense of adding complexity and at times, reduced total power. As a result, HEV generally lack the dynamic performance that customers enjoy. To address this issue, the paper presents a HEV with eAWD capabilities via the use of a torque vectoring electric rear axle drive (TVeRAD) unit to power the rear axle. The addition of TVeRAD to a front wheel drive HEV improves the total power output. To further improve the handling characteristics of the vehicle, the TVeRAD unit allows for wheel torque vectoring at the rear axle. A bond graph model of the proposed drivetrain model is developed and used in co-simulation with CarSim. The paper proposes a control system which utilizes tire force optimization to allocate control to each tire. The optimization algorithm is used to obtain optimal tire force targets to at each tire such that the targets avoid tire saturation.
2017-03-28
Technical Paper
2017-01-1560
Wei Liu, Lu Xiong, Bo Leng, Haolan Meng, Renxie Zhang
Abstract In this paper, a novel method is proposed to establish the vehicle yaw stability criterion based on the sideslip angle-yaw rate (β-r) phase plane method. First, nonlinear two degrees of freedom vehicle analysis model is established by adopting the Magic Formula of nonlinear tire model. Then, according to the model in the Matlab/Simulink environment, the β-r phase plane is gained. Emphatically, the effects of different driving conditions (front wheels steering angle, road adhesion coefficient and speed) on the stability boundaries of the phase plane are analyzed. Through a large number of simulation analysis, results show that there are two types of phase plane: curve stability region and diamond stability region, and the judgment method of the vehicle stability domain type under different driving conditions is solved.
2017-03-28
Technical Paper
2017-01-1571
Kevin McLaughlin, Jonah Shapiro, HyungJu Kwon
Abstract An approach to electric steering control and tuning is developed using vehicle dynamics and quantitative steering objectives. The steering objective chosen is the torque vs. lateral acceleration target for the driver termed the “steering gain”. Two parameters are derived using vehicle dynamics that substantially determine driver feel: the vehicle’s “manual gain” (total steering torque divided by lateral acceleration) and the vehicle’s lateral acceleration gain (lateral acceleration divided by steering angle). Lateral acceleration gain is a well-known quantity in the literature but “manual gain” is a nonstandard point of view for steering control systems. The total gain inside the controller is the loop gain; generally, the higher the loop gain, the better the controller rejects unwanted effects such as friction. For a typical torque-input electric steering topology, it is shown that the relationship between loop gain and steering gain is unique.
2017-03-28
Technical Paper
2017-01-1575
Andrei Keller, Sergei Aliukov, Vladislav Anchukov
Abstract Trucks are one of the most common modes of transport and they are operated in various road conditions. As a rule, all-wheel drive trucks are equipped with special systems and mechanisms to improve their off-road capability and overall efficiency. The usage of blocked mechanisms for power distribution is one of the most popular and effective ways to improve the off-road vehicle performance. However, the lock of differential may adversely affect the stability and control of vehicle because of the unobvious redistribution of reactions acting on wheels, which consequently leads to poor performance and safety properties. Problems of rational distribution of power in transmissions of all-wheel drive vehicles, as well as research in the field of improving directional stability and active safety systems are among the priorities in modern automotive industry.
2017-03-28
Journal Article
2017-01-1569
Amro Elhefnawy, Alhossein sharaf, Hossam Ragheb, Shawky Hegazy
Abstract This paper presents an advanced control system, which integrates three fuzzy logic controllers namely; Direct Yaw-moment Control (DYC), Active Roll-moment Control (ARC) and Active Front Steering (AFS) to enhance vehicle cornering and overturning stability. Based on a well-developed and validated fourteen degree of freedom (DOF) full vehicle model with non-linear tire characteristics, a reference 3-DOF yaw-roll plane vehicle model is introduced to control yaw rate, sideslip angle, and roll angle of the vehicle body. The control actions of both direct yaw and active roll moments are performed by generating differential braking moments across the front wheels, while the control action of the active steering is performed by modifying the steering wheel angle. Different standard cornering tests are conducted in MATLAB / Simulink environment such as J-turn, fishhook and lane change maneuvers.
2017-03-28
Technical Paper
2017-01-1579
Liang-kuang Chen, Chien-An Chen
Abstract The development of an integrated controller for a 4WS/4WD electric bus is investigated. The front wheel steering angle is assumed to be controlled by the human driver. The vehicle is controlled by the rear wheel steering and the yaw moment that can be generated by the differential torque/brake control on each wheel. The high speed cornering is used as the testing scenario to validate the designed controller. Due to the highly nonlinear and the multiple-input and multiple-output nature, the control design is separated into different stages using the hierarchical layer control concept. The longitudinal speed is controlled using a PI controller together with a rule-based speed modification. The other two control inputs, namely the rear wheel steering and the DYC moment, are then designed using the state-dependent Riccati equation method. The designed controllers are evaluated using computer simulations first, and the simulations showed promising results.
2017-03-28
Technical Paper
2017-01-1581
Jianbo Lu, Hassen Hammoud, Todd Clark, Otto Hofmann, Mohsen Lakehal-ayat, Shweta Farmer, Jason Shomsky, Roland Schaefer
Abstract This paper presents two brake control functions which are initiated when there is an impact force applied to a host vehicle. The impact force is generated due to the host vehicle being collided with or by another vehicle or object. The first function - called the post-impact braking assist - initiates emergency brake assistance if the driver is braking during or right after the collision. The second function - called the post-impact braking - initiates autonomous braking up to the level of the anti-lock-brake system if the driver is not braking during or right after the collision. Both functions intend to enhance the current driver assistance features such as emergency brake assistance, electronic stability control, anti-brake-lock system, collision mitigation system, etc.
2017-03-28
Technical Paper
2017-01-1585
Renxie Zhang, Lu Xiong, Zhuoping Yu, Wei Liu
Abstract A dynamic controller is designed for unmanned skid-steering vehicle. The vehicle speed is controlled through driving torque of engine to achieve the desired vehicle speed and the steering is controlled through hydraulic braking on each side of the vehicle to achieve the desired yaw rate. Contrary to the common approaches by considering non-holonomic constraints, tire slip and saturation of actuators torque influencing the driving and braking are considered, based on the analysis of vehicle dynamic model and nonlinear tire model. Hence, with conditional integrators, the dynamic controller overcoming integral saturation is designed to ensure the accurate tracking for desired signals under influence of tire forces and constraint of actuators. In addition, the exponential kind filter is utilized to enhance the ability of smoothing noise of wheel speed. To perform small radius cornering maneuvers, a dynamic control strategy for steering when vehicle speed is zero is also designed.
2017-03-28
Technical Paper
2017-01-1176
Hafiz S. Khafagy
Abstract Auto stop-start (Engine stop-start, ESS) has become a widely used feature to reduce fuel consumption and CO2 emissions particularly in congested cities. Typically, vehicles equipped with such systems include two DC power sources that are coupled in parallel: a primary and a secondary power source. The primary power source supplies energy to the starter to crank the engine, while the secondary power source supplies energy to the rest of the vehicle electric loads. During an auto-stop event, a controllable switch decouples the two power sources. Moreover, operating current, voltage and the State of Charge (SOC) are monitored to ensure enough energy for the next auto-start event. When any of these operating parameters are below the threshold values, the controllable switch opens to isolate the two batteries and then the engine is automatically started.
2017-03-28
Technical Paper
2017-01-1427
Daniel Koch, Gray Beauchamp, David Pentecost
Abstract Tire disablement events can cause a drag force that slows a vehicle. In this study, the magnitude of the deceleration was measured for different phases of 29 high speed tire tread separation and air loss tests. These deceleration rates can assist in reconstructing the speed of a vehicle involved in an accident following a tire disablement.
2017-03-28
Technical Paper
2017-01-0459
Salah H. R. Ali, Badr S. N. Azzam, T. A. Osman, A. M. Moustafa
Abstract The frictional composite is an important material in braking system for automotive, trucks or heavy-duty vehicles. In this paper, a proposed frictional composite material has been developed to achieve the ISO requirements for heavy-duty vehicle brakes. This new frictional material has been fabricated with various compositions. Tribological, chemical, mechanical, thermal conductivity and acoustic noise level tests have measure its performance compared to other two commercial samples under certain operating conditions. Surface characteristics of selected samples have been performed using white light optical microscopy (WLOM) in 2D images to insure the material homogeneity. Additionally, surface roughness analyses using atomic force microscopy (AFM) into 2D and 3D images before and after frictional operation have been investigated.
2017-03-28
Technical Paper
2017-01-1405
Tzu-Sung Wu
Abstract Autonomous Emergency Braking Systems (AEBS) usually contain radar, (stereo) camera and/or LiDAR-based technology to identify potential collision partners ahead of the car, such that to warn the driver or automatically brake to avoid or mitigate a crash. The advantage of camera is less cost: however, is inevitable to face the defects of cameras in AEBS, that is, the image recognition cannot perform good accuracy in the poor or over-exposure light condition. Therefore, the compensation of other sensors is of importance. Motivated by the improvement of false detection, we propose a Pedestrian-and-Vehicle Recognition (PVR) algorithm based on radar to apply to AEBS. The PVR employs the radar cross section (RCS) and standard deviation of width of obstacle to determine whether a threshold value of RCS and standard deviation of width of the pedestrian and vehicle is crossed, and to identity that the objective is a pedestrian or vehicle, respectively.
2017-03-28
Journal Article
2017-01-1573
Andreas Carlitz, Sebastien Allibert, Thomas Schmitz, Axel Engels
Abstract A twistbeam is a very cost effective rear suspension architecture which has drawbacks compared to an independent rear suspension. One drawback is the lateral compliance during cornering compromising the handling of the vehicle. Common solutions to correct this issue are complex reinforcements or an additional Watts linkage. However, these solutions drive high cost and additional weight. The challenge was to find a solution which reduces the gap to the functional performance of a multilink rear suspension. Due to the bush attachment, the set-up of a twistbeam is always a compromise between ride comfort and vehicle dynamics. The more comfort is desired the softer the bushings will be, resulting in less agility and slower vehicle response. The target was to determine a way to separate ride comfort and dynamic agility. A solution was found using a special set of springs working as a dynamic anti-compliance mechanism.
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