Display:

Results

Viewing 121 to 150 of 10236
2015-04-14
Journal Article
2015-01-1594
Johannes Edelmann, Massimiliano Gobbi, Giampiero Mastinu, Manfred Ploechl, Giorgio Previati
Abstract The friction estimation at the tire-ground contact is crucial for the active safety of vehicles. Friction estimation is a key problem of vehicle dynamics and the ultimate solution is still unknown. However the proposed approach, based on a simple idea and on a simple hardware, provides an actual solution. The idea is to compare the tire characteristic at a given friction (nominal characteristic) with the actual characteristic that the tire has while running. The comparison among these two characteristics (the nominal one and the actual one) gives the desired friction coefficient. The friction coefficient is expressed in vector form and a number of running parameters are identified. The mentioned comparison is an efficient but complex algorithm based on a mathematical formulation of the tire characteristic.
2015-04-14
Journal Article
2015-01-1597
Kazuto Yokoyama, Masahiro Iezawa, Hideyuki Tanaka, Keiichi Enoki
Abstract Mitsubishi Electric has developed a concept car “EMIRAI 2 xEV” that features an electric vehicle (EV) powertrain for safe, comfortable, eco-friendly driving experiences in the future. The vehicle was exhibited during the 2013 Tokyo Motor Show and the 2014 Automotive Engineering Exposition. The xEV is a four-wheel-drive EV with three motors: a water-cooled front motor and two air-cooled rear motors with integrated inverters. The rear wheels can be driven independently. The degrees of freedom of the actuation can realize improved maneuverability and safety. The vehicle is also equipped with an onboard charger with a built-in step down DC/DC converter, an EV control unit, a battery management unit, and electric power steering. All of the instruments are developed by Mitsubishi Electric. Motion control systems for the xEV have been developed based on our proprietary motor control technology.
2015-04-14
Journal Article
2015-01-1755
Atsushi Hirano
Abstract This paper studies various wheel stiffness configurations, with the aim of enhancing driving stability while minimizing the increase in weight associated with an increase in stiffness. Reinforcement was added to the wheel disk and the wheel rim of standard aluminum wheels for passenger vehicles in order to produce four wheels with different stiffness configurations. The effects of disk stiffness and rim stiffness on tire contact patch profiles and driving stability were quantitatively evaluated. From the results of tests with the four wheels, it was observed that disk stiffness and rim stiffness have differing effects on tire contact patch profiles, and on driving stability. Disk stiffness influences especially tire contact patch length, and tire contact patch length influences especially maneuverability in driving stability. Rim stiffness influences especially tire contact patch area, and tire contact patch area influences especially stability in driving stability.
2015-04-14
Technical Paper
2015-01-1414
Jitendra Shah, Mohamed Benmimoun
Abstract The focus of this paper is the threat assessment of perceived threat by drivers in collision avoidance situations. The understanding of the decision making process with regards to the initiation of a driver intervention is a crucial step to gain insight into driver's steering and braking behavior in case of an imminent threat (rear-end collision). Hence a study with various test subjects and a test vehicle has been conducted. The study has helped to understand how drivers behave in potential rear-end collision situations arising from the traffic situation (e.g. start of a traffic jam). This information is of major importance for designing autonomous collision avoidance systems and an important step towards autonomous driving. Autonomous driving in vehicles require system interventions to be initiated as early and safely as possible in order to avoid the collision and to avoid unstable vehicle dynamics situations.
2015-04-14
Technical Paper
2015-01-1410
Shotaro Odate, Kazuhiro Daido, Yosuke Mizutani
Abstract According to the North American National Automotive Sampling System Crashworthiness Data System (NASS/CDS), approximately one-half of all accidents during driving are of the secondary collision pattern in which the collision event involves the occurrence of secondary collision. Accidents involving impact to a stopped vehicle (chain-reaction collisions) have increased to approximately 3% of all accidents in North America, and although the rate of serious injury is low, cases have been reported of accidents in which cervical sprain occurs as an after-effect[1]. In order to mitigate these circumstances, research has been conducted on systems of automatic braking for collisions. These systems apply brakes automatically when a first collision has been detected in order to avoid or lessen a second collision. Research on automatic collision braking systems, however, has not examined the multiple collisions parked [1, 2].
2015-04-14
Technical Paper
2015-01-1237
Xiaoming Chen, Jeff L. Conklin, Robert M. Carpenter, Jeff Wallace, Cynthia Flanigan, David A. Wagner, Vijitha Kiridena, Stephane Betrancourt, Jason Logsdon
Abstract The Multi Material Lightweight Vehicle (MMLV) developed by Magna International and Ford Motor Company is a result of a US Department of Energy project DE-EE0005574. The project demonstrates the lightweighting potential of a five passenger sedan, while maintaining vehicle performance and occupant safety. Prototype vehicles were manufactured and limited full vehicle testing was conducted. The Mach-I vehicle design, comprised of commercially available materials and production processes, achieved a 364kg (23.5%) full vehicle mass reduction, enabling the application of a 1.0-liter three-cylinder engine resulting in a significant environmental benefits and fuel consumption reduction. As part of this project, several automotive chassis components were selected for development and evaluation on the MMLV C/D segment passenger sedan.
2015-04-14
Technical Paper
2015-01-1417
Jeffrey Muttart
Abstract Controlled studies identified several factors that influence drivers' swerving when responding to in an emergency situation. Specifically, driver age, time-to-contact, amplitude of the steering action (steer within lane or swerving into the next lane), distraction, fatigue, natural lighting and available buffer space were identified as factors that influence steering behaviors. The goal of the current research was to identify the extent to which each factor changed swerving performances of drivers who were faced with a crash or near crash. Results from crashes and near crashes were obtained from the InSight (SHRP-2) naturalistic driving study. The results from the controlled studies and the results from the naturalistic driving research were consistent in many ways. Drivers engaged in a visual-manual secondary task were much younger than were the drivers who had no distracting secondary task.
2015-04-14
Technical Paper
2015-01-1345
Srinivas Kurna, Arpit Mathur, Sandeep Sharma
Abstract In commercial vehicle, Leaf Spring design is an important milestone during product design and development. Leaf springs are the most popular designs having multiple leaves in contact with each other and show hysteresis behavior when loaded and unloaded. Commonly used methods for evaluation of leaf spring strength like endurance trials on field and Rig testing are time consuming and costly. On the other hand, virtual testing methods for strength and stiffness evaluation give useful information early in the design cycle and save considerable time and cost. They give flexibility to evaluate multiple design options and accommodate any design change early in development cycle. A study has been done in Volvo-Eicher to correlate Rig result with Finite Element Analysis (FEA) simulation result of Multi-stage Suspension Leaf Spring, entirely through Finite Element Analysis route.
2015-04-14
Technical Paper
2015-01-1118
Fengyu Liu, Li Chen, Jian Yao, Jianlong Zhang, Chengliang Yin, Dongxu Li, Chunhao Lee, Ying Huang
Abstract Dry dual clutch transmission (DCT) has played an important role in the high performance applications as well as low-cost market sectors in Asia, with a potential as the future mainstream transmission technology due to its high mechanical efficiency and driving comfort. Control system simplification and cost reduction has been critical in making dry DCT more competitive against other transmission technologies. Specifically, DCT clutch actuation system is a key component with a great potential for cost-saving as well as performance improvement. In this paper, a new motor driven clutch actuator with a force-aid lever has been proposed. A spring is added to assist clutch apply that can effectively reduce the motor size and energy consumption. The goal of this paper is to investigate the feasibility of this new clutch actuator, and the force-aid lever actuator's principle, physical structure design, and validation results are discussed in details.
2015-04-14
Journal Article
2015-01-0314
Junyung Lee, Beomjun Kim, Jongsang Seo, Kyongsu Yi, Jihyun Yoon, Bongchul Ko
Abstract This paper presents an automated driving control algorithm for the control of an autonomous vehicle. In order to develop a highly automated driving control algorithm, one of the research issues is to determine a safe driving envelope with the consideration of probable risks. While human drivers maneuver the vehicle, they determine appropriate steering angle and acceleration based on the predictable trajectories of the surrounding vehicles. Therefore, not only current states of surrounding vehicles but also predictable behaviors of that should be considered in determining a safe driving envelope. Then, in order to guarantee safety to the possible change of traffic situation surrounding the subject vehicle during a finite time-horizon, the safe driving envelope over a finite prediction horizon is defined in consideration of probabilistic prediction of future positions of surrounding vehicles.
2015-04-14
Journal Article
2015-01-1599
Bo Leng, Lu Xiong, Chi Jin, Jun Liu, Zhuoping Yu
Abstract For an electric vehicle driven by four in-wheel motors, the torque of each wheel can be controlled precisely and independently. A closed-loop control method of differential drive assisted steering (DDAS) has been proposed to improve vehicle steering properties based on those advantages. With consideration of acceleration requirement, a three dimensional characteristic curve that indicates the relation between torque and angle of the steering wheel at different vehicle speeds was designed as a basis of the control system. In order to deal with the saturation of motor's output torque under certain conditions, an anti-windup PI control algorithm was designed. Simulations and vehicle tests, including pivot steering test, lemniscate test and central steering test were carried out to verify the performance of the DDAS in steering portability and road feeling.
2015-04-14
Journal Article
2015-01-0432
Xingxing Feng, Jinglai Wu, Yunqing Zhang, Ming Jiang
Abstract The optimization of vehicle suspension kinematic/compliance characteristics is of significant importance in the chassis development. Practical suspension system contains many uncertainties which may result from poorly known or variable parameters or from uncertain inputs. However, in most suspension optimization processes these uncertainties are not accounted for. This study explores the use of Chebyshev polynomials to model complex nonlinear suspension systems with interval uncertainties. In the suspension model, several kinematic and compliance characteristics are considered as objectives to be optimized. Suspension bushing characteristics are considered as design variables as well as uncertain parameters. A high-order response surface model using the zeros of Chebyshev polynomials as sampling points is established to approximate the suspension kinematic/compliance model.
2015-04-14
Journal Article
2015-01-0489
Jason Rogers
Abstract A 3D-and-Excel-based predictive tool was developed to determine trunk spring movement for preventing recurrence of a noise problem. While effective, the tool could not completely explain measured results on the completed body unit (CBU). Since design data is used as the input, it was hypothesized that the difference between predicted and actual results was related to tolerance variation on the actual vehicle. Using Siemens® Variation Analysis software, the CBU was built and simulated virtually with tolerances using a Monte Carlo model. The study found that the hypothesis was correct; tolerance variation was fully responsible for the differences. In addition, the study also allowed accurate prediction of failure rates.
2015-04-14
Journal Article
2015-01-0518
Hirokuni Fuchigami
Abstract In this research, a new wire material made using surface-reforming heat treatment was developed in order to enhance the corrosion fatigue resistance of suspension springs. The aim of surface reforming is to improve hydrogen embrittlement characteristics through grain refinement and to improve crack propagation resistance by partial softening of hardness. The grain refinement method used an α'→γ reversed transformation by rapid short-term heating in repeated induction heating and quenching (R-IHQ) to refine the crystal grain size of SAE 9254 steel spring wire to 4 μm or less. In order to simultaneously improve the fatigue crack propagation characteristics, the possibility of reducing the hardness immediately below the spring surface layer was also examined. By applying contour hardening in the second IHQ cycle, a heat affected zone (HAZ) is obtained immediately below the surface.
2015-04-14
Journal Article
2015-01-0622
H. Metered, A. Elsawaf, T. Vampola, Z. Sika
Abstract Proportional integral derivative (PID) control technique is the most common control algorithm applied in various engineering applications. Also, particle swarm optimization (PSO) is extensively applied in various optimization problems. This paper introduces an investigation into the use of a PSO algorithm to tune the PID controller for a semi-active vehicle suspension system incorporating magnetorheological (MR) damper to improve the ride comfort and vehicle stability. The proposed suspension system consists of a system controller that determine the desired damping force using a PID controller tuned using PSO, and a continuous state damper controller that estimate the command voltage that is required to track the desired damping force. The PSO technique is applied to solve the nonlinear optimization problem to find the PID controller gains by identifying the optimal problem solution through cooperation and competition among the individuals of a swarm.
2015-04-14
Journal Article
2015-01-0632
Xiang Liu, Jie Zhang, Jingshan Zhao
Abstract Suspension plays an essential role in vehicle's handling stability and riding comfort. This paper discusses a novel suspension that has the capacity to trace a straight line in theory. Therefore it is called rectilinear suspension. So the alignment parameters are invariable during jounce and rebound if the elasticity of suspension components is ignored. According to the structure characteristics of the rectilinear suspension, it is suitable to mount on the rear axle. To evaluate its performance, the dynamics model is established through ADAMS. Moreover, a comparison of the rectilinear suspension with the twin-trapezoidal link suspension is carried out. Further, the K&C test results show that the alignment parameters of the rectilinear suspension are almost invariable compared with MacPherson suspension.
2015-04-14
Journal Article
2015-01-0642
Per Hyldahl, Sebastian Andersen, Sebastian Mikkelsen, Ole Balling
Abstract This study concerns the modeling of the stabilizer bar in a car suspension. This is a crucial and difficult task if its non-linear behavior should be captured correctly. In this study, the modeling of a stabilizer bar is done using beam finite elements based on the absolute nodal coordinate formulation (ANCF). An ANCF beam element is reviewed and its implementation in a multibody dynamics framework is explained. The specific element is chosen since it is assumed to be appropriate for modeling stabilizer bars. To test the feasibility of using the chosen ANCF beam element for modeling stabilizer bars, several numerical studies have been performed. These include eigenfrequency and static analyzes where results obtained using ANCF beam elements are compared with results obtained using other methods.
2015-04-14
Journal Article
2015-01-0643
Dzmitry Savitski, Kristian Hoepping, Valentin Ivanov, Klaus Augsburg
Abstract The presented study demonstrates results of experimental investigations of the anti-lock braking system (ABS) performance under variation of tire inflation pressure. This research is motivated by the fact that the changes in tire inflation pressure during the vehicle operation can distinctly affect peak value of friction coefficient, stiffness and other tire characteristics, which are influencing on the ABS performance. In particular, alteration of tire parameters can cause distortion of the ABS functions resulting in increase of the braking distance. The study is based on experimental tests performed for continuous ABS control algorithm, which was implemented to the full electric vehicle with four individual on-board electric motors. All straight-line braking tests are performed on the low-friction surface where wheels are more tended to lock.
2015-04-14
Journal Article
2015-01-0645
Jian Zhao, Jin Zhang, Bing Zhu
Abstract The longitudinal dynamics control is an essential task of vehicle dynamics control. In present, it is usually applied by adjusting the slip ratio of driving wheels to achieve satisfactory performances both in stability and accelerating ability. In order to improve its performances, the coordination of different subsystems such as engine, transmission and braking system has to be considered. In addition, the proposed algorithms usually adopt the threshold methods based on less road condition information for simpleness and quick response, which cannot achieve optimal performance on various road conditions. In this paper, an integrated longitudinal vehicle dynamics control algorithm with tire/road friction estimation was proposed. First, a road identification algorithm was designed to estimate tire forces of driving wheels and the friction coefficient by the method of Kalman Filter and Recursive Least Squares (RLS).
2015-04-14
Journal Article
2015-01-0649
Liangyao Yu, Shuhao Huo, WenWei Xuan, Lei Zuo
Abstract Conventional viscous shock absorbers, in parallel with suspension springs, passively dissipate the excitation energy from road irregularity into heat waste, to reduce the transferred vibration which causes the discomfort of passengers. Energy-harvesting shock absorbers, which have the potential of conversion of kinetic energy into electric power, have been proposed as semi-active suspension to achieve better balance between the energy consumption and suspension performance. Because of the high energy density of the rotary shock absorber, a rotational energy-harvesting shock absorber with mechanical motion rectifier (MMR) is used in this paper. This paper presents the assessment of vehicle dynamic performance with the proposed energy-harvesting shock absorber in braking process. Moreover, a PI controller is proposed to attenuate the negative effect due to the pitch motion.
2015-04-14
Journal Article
2015-01-0651
Mustafa Ali Arat, Saied Taheri, Edward Holweg
The road profile has been shown to have significant effects on various vehicle conditions including ride, handling, fatigue or even energy efficiency; as a result it has become a variable of interest in the design and control of numerous vehicle parts. In this study, an integrated state estimation algorithm is proposed that can provide continuous information on road elevation and profile variations, primarily to be used in active suspension controls. A novel tire instrumentation technology (smart tire) is adopted together with a sensor couple of wheel attached accelerometer and suspension deflection sensor as observer inputs. The algorithm utilizes an adaptive Kalman filter (AKF) structure that provides the sprung and unsprung mass displacements to a sliding-mode differentiator, which then yields to the estimation of road elevations and the corresponding road profile along with the quarter car states.
2015-04-14
Journal Article
2015-01-0655
Francesco Calabrese, Manfred Baecker, Carlos Galbally, Axel Gallrein
Abstract Currently used tire models have shown a certain lack of accuracy in some advanced handling applications. This lack of accuracy is believed to be partly due to thermal effects. In reality, the tire rubber temperature is not constant during the normal operating conditions and it's really well known that the tire friction coefficient strongly depends on the temperature level. The temperature generation, propagation and evolution are the result of a dynamic energy equilibrium between phenomena of different natures. Various mechanisms create a non-uniform temperature distribution in various parts of the tire structure: heat is generated in zones with large cyclic deformations due to the energy dissipated from the rubber strains and in the sliding part of the contact patch due to friction. The rubber cools down because the heat energy transferred to the air (internally and externally) and to the asphalt in the stick zone of the contact patch.
2015-04-14
Journal Article
2015-01-0656
Amir Soltani, Francis Assadian
Abstract A new control strategy for wheel slip control, considering the complete dynamics of the electro-hydraulic brake (EHB) system, is developed and experimentally validated in Cranfield University's HiL system. The control system is based on closed loop shaping Youla-parameterization method. The plant model is linearized about the nominal operating point, a Youla parameter is defined for all stabilizing feedback controller and control performance is achieved by employing closed loop shaping technique. The stability and performance of the controller are investigated in frequency and time domain, and verified by experiments using real EHB smart actuator fitted into the HiL system with driver in the loop.
2015-04-14
Journal Article
2015-01-0665
Yongchang Du, Yujian Wang, Pu Gao, Yingping Lv
Abstract Modelling of disc in brake squeal analysis is complicated because of the rotation of disc and the sliding contact between disc and pads. Many analytical or analytical numerical combined modeling methods have been developed considering the disc brake vibration and squeal as a moving load problem. Yet in the most common used complex eigenvalue analysis method, the moving load nature normally has been ignored. In this paper, a new modelling method for rotating disc from the point of view of modal is presented. First finite element model of stationary disc is built and modal parameters are calculated. Then the dynamic response of rotating disc which is excited and observed at spatial fixed positions is studied. The frequency response function is derived through space and time transformations. The equivalent modal parameter is extracted and expressed as the function of rotation speed and original stationary status modal parameters.
2015-04-14
Journal Article
2015-01-0668
Yongchang Du, Pu Gao, Yujian Wang, Yingping Lv
Abstract The study and prevention of unstable vibration is a challenging task for vehicle industry. Improving predicting accuracy of braking squeal model is of great concern. Closed-loop coupling disc brake model is widely used in complex eigenvalue analysis and further analysis. The coupling stiffness of disc rotor and pads is one of the most important parameters in the model. But in most studies the stiffness is calculated by simple static force-deformation simulation. In this paper, a closed-loop coupling disc brake model is built. Initial values of coupling stiffness are estimated from static calculation. Experiment modal analysis of stationary disc brake system with brake line pressure and brake torques applied is conducted. Then an optimization process is initiated to minimize the differences between modal frequencies predicted by the stationary model and those from test. Thus model parameters more close to reality are found.
2015-04-14
Journal Article
2015-01-0667
Kei Ichikawa
Abstract Cabin quietness is one of the important factors for product marketability. In particular, the importance of reducing road noise is increasing in recent years. Methods that reduce acoustic sensitivity as well as those that reduce the force transferred from the suspension to the body (the suspension transfer force) are used as means of reducing road noise. Reduction of the compliance of the body suspension mounting points has been widely used as a method of reducing acoustic sensitivity. However, there were cases where even though this method reduced acoustic sensitivity, road noise did not decrease. This mechanism remained unclear. This study focused on the suspension transfer force and analyzed this mechanism of change using the transfer function synthesis method. The results showed that the balance between the body's suspension mounting points, suspension bush, and suspension arm-tip compliance is an important factor influencing the change in suspension transfer force.
2015-04-14
Journal Article
2015-01-1309
Hyunggyung Kim
Abstract This Study describes about the development of new concept' rear wheel guards for the reduction of Road Noise in the passenger vehicles. The new wheel guards are proposed by various frequency chamber concept and different textile layers concept. Two wheel guards were verified by small cabin resonance and vehicle tests. Through new developing process without vehicle test, Result of road noise will be expected if this concepts and materials of wheel guard are applied into automotive vehicle. As this concept consider tire radiation noise frequency and multilayers sound control multilayers, 2 concepts reduced road noise from 0.5 to 1.0dB. The proposed method of part reverberant absorption is similar to results of vehicle tests by part absorption index. Furthermore, optimization of frequency band in wheel guards will reduce more 0.5 dB noises.
2015-04-14
Journal Article
2015-01-1314
Max Sardou, Patricia Djomseu
Abstract SARDOU SAS has developed highly stressed composites parts for 35 years. SARDOU SAS and QUALITY INDUSTRIAL PRODUCT invented composite coils springs in 2002. Developing composite coils springs, we have faced a big challenge, how to increase the short life expectancy of this highly stressed structure? We have identified that the weak point, in composite coils springs, is its epoxy matrix. In fact, during heavy loading, the matrix undergoes micro cracks. Then, during fatigue, micro cracks propagate and merge, transforming the matrix into a fine powder. The composite coil suspension springs, using, classic epoxy, where ruined after only 100,000 cycles in the best cases. The fact to integrate “functionalized silica aggregates”, in the matrix, enable the springs to exceed 1,000,000 cycles, with the same spring design. In addition, the spring stiffness has increased by 6% and the thermal set has reduced by 1.6%.
2015-04-14
Journal Article
2015-01-1505
Ibrahim A. Badiru
Abstract Vehicle steering wheel pull is a condition experienced by customers where a constant torque at the steering wheel is required to maintain a straight path. Steering wheel pull may be accompanied by the secondary effects of steering wheel angle misalignment and vehicle thrust angle “dog-tracking.” EPS pull compensation is a feature that can automatically compensate vehicle steering wheel pull. This paper examines customer benefits, operating principles, effectiveness, and robustness of EPS pull compensation in vehicles. Vehicle road test data indicate EPS can correct a severe vehicle steering wheel pull. Using fundamental physics equations, an analysis tool is derived to support further investigation of steering wheel angle misalignment and vehicle thrust angle. The final section presents a designed experiment revealing parameters most influencing vehicle robustness to chassis and road characteristics.
2015-04-14
Journal Article
2015-01-1506
Bastian Scheurich, Tilo Koch, Michael Frey, Frank Gauterin
Abstract Today, body vibration energy of passenger cars gets dissipated by linear working shock absorbers. A new approach substitutes the damper of a passenger car by a cardanic gimbaled flywheel mass. The constructive design leads to a rotary damper in which the vertical movement of the wheel carrier leads to revolution of the rotational axis of the flywheel. In this arrangement, the occurring precession moments are used to control damping moments and to store vibrational energy. Different damper characteristics are achieved by different induced precession. From almost zero torque output to high torque output, this damper has a huge spread. Next to the basic principal, in this paper an integration in the chassis, including a constructive proposal is shown. A conflict with high torque and high angular velocity leads to a special design. Moreover concepts to deal with all vehicle situations like yawing, rolling and pitching are shown.
Viewing 121 to 150 of 10236

Filter