Criteria

Display:

Results

Viewing 211 to 240 of 9914
Technical Paper
2014-04-01
Guangzhong Xu, Nong Zhang
This paper presents the modeling and characteristic analysis of roll-plane and pitch-plane combined Hydraulically Interconnected Suspension (HIS) system. Vehicle dynamic analysis is carried out with four different configurations for comparison. They are: 1) vehicle with spring-damper only, 2) vehicle with roll-plane HIS, 3) vehicle with pitch-plane HIS and 4) vehicle with roll and pitch combined HIS. The modal analysis shows the unique modes-decoupling property of HIS system. The roll-plane HIS increases roll stiffness only without affecting other modes, and similarly pitch-plane HIS increases the pitch stiffness only with minimum influence on other modes. When roll and pitch plane HIS are integrated, the vehicle ride comfort and handling stability can be improved simultaneously without compromise. A detailed analysis and discussion of the results are provided to conclude the paper.
Technical Paper
2014-04-01
David H. Myszka, Jonathan Lauden, Patrick Joyce, Andrew Murray, Christoph Gillum
Automotive starting systems require substantial amounts of mechanical energy in a short period of time. Lead-acid batteries have historically provided that energy through a starter motor. Springs have been identified as an alternative energy storage medium and are well suited to engine-starting applications due to their ability to rapidly deliver substantial mechanical power and their long service life. This paper presents the development of a conceptual, spring-based starter. The focus of the study was to determine whether a spring of acceptable size could provide the required torque and rotational speed to start an automotive engine. Engine testing was performed on a representative 600 cc, inline 4-cylinder internal combustion engine to determine the required torque and engine speed during the starting cycle. An optimization was performed to identify an appropriate spring design, minimizing its size. Results predict that the test engine could be started by a torsional steel spring with a diameter and length of approximately 150 mm, similar in size, but lower weight than an electrical starting system of the engine.
Technical Paper
2014-04-01
Ankang Jin, Weiguo Zhang, Shihu Wang, Yu Yang, Yunqing Zhang
The suspension system of a heavy truck's driver seat plays an important role to reduce the vibrations transmitted to the seat occupant from the cab floor. Air-spring is widely used in the seat suspension system, for the reason that its spring rate is variable and it can make the seat suspension system keep constant ‘tuned’ frequency compared to the conventional coil spring. In this paper, vibration differential equation of air-spring system with auxiliary volume is derived, according to the theory of thermodynamic, hydrodynamics. The deformation-load static characteristic curves of air-spring is obtained, by using a numerical solution method. Then, the ADAMS model of the heavy truck's driver seat suspension system is built up, based on the structure of the seat and parameters of the air-spring and the shock-absorber. At last, the model is validated by comparing the simulation results and the test results, considering the seat acceleration PSD and RMS value.
Technical Paper
2014-04-01
Austin Gurley
Abstract Selection of springs and dampers is one of the most important considerations when finalizing a race car suspension design. It is also one of most complex due to the dynamic interaction of the vehicle with the ground. Current tuning methods for spring and dampers' effect on vehicle ride can be based on simplified dynamic models of the vehicle, such as the quarter-car model. While efficient computationally, the traditional quarter-car model does not account for the non-linear variation in grip seen by a fluctuating contact-patch. Both amplitude and frequency of suspension oscillation contribute to loss of tire grip. The method can be improved by incorporation of a dynamic tire model, though resulting in non-linear effects. An improved ‘rolling quarter-car’ model is created, which includes the effect of dynamic tire forces in the analysis of improved grip. Using typical Formula SAE race car, characteristics as a test case, a linearized dynamic model is made. The effect of suspension parameters on the dynamic tire forces produced are surveyed.
Technical Paper
2014-04-01
Chen Lv, Junzhi Zhang, Yutong Li, Ye Yuan
Abstract Regenerative braking, which can effectively improve vehicle's fuel economy by recuperating the kinetic energy during deceleration processes, has been applied in various types of electrified vehicle as one of its key technologies. To achieve high regeneration efficiency and also guarantee vehicle's brake safety, the regenerative brake should be coordinated with the mechanical brake. Therefore, the regenerative braking control performance can be significantly affected by the structure of mechanical braking system and the brake blending control strategy. By-wire brake system, which mechanically decouples the brake pedal from the hydraulic brake circuits, can make the braking force modulation more flexible. Moreover, its inherent characteristic of ‘pedal-decouple’ makes it well suited for the implementation in the cooperative regenerative braking control of electrified vehicles. With the aims of regeneration efficiency and braking performance, a regenerative braking control algorithm for electrified vehicles equipped with a brake-by-wire system is researched in this paper.
Collection
2014-04-01
This technical paper collection focuses on new theory, formulation and modeling of amplitude-, frequency- and temperature-dependent nonlinear components/systems such as rubber and hydraulic mounts or bushings, shock absorbers, and any joint friction/damping; dynamic characterization through lab and field testing; Linearization methodology; Model validation, application, and sensitivity analysis in vehicle system/subsystem simulations; Nonlinear system identification, modeling, and application in testing accuracy improvement, etc.
Collection
2014-04-01
This technical paper collection is focused on vehicle dynamics and controls using modeling and simulation, and experimental analysis of passenger cars, heavy trucks, and wheeled military vehicles. The papers address active and passive safety systems to mitigate rollover, yaw instability and braking issues; driving simulators and hardware-in-the-loop systems; suspension kinematics and compliance, steering dynamics, advanced active suspension technologies; and tire force and moment mechanics.
Collection
2014-04-01
This technical paper collection presents papers on steering and suspension related topics as it applies to ground vehicles. Papers for this session address new approaches as well as advances in application of steering, suspension related technologies.
Technical Paper
2014-04-01
Lee Carr, Dan Barnes, Jennifer Crimeni
Abstract Prior to the widespread implementation of ABS brake technology in light vehicles, driver training often included instruction to “pump the brakes” to avoid locking the wheels. Many driver education programs now recommend maintaining high brake pedal force and relying on ABS. It is sometimes asserted that drivers desiring to stop a vehicle quickly still “pump the brakes”. Investigators sought to understand whether drivers desiring to decelerate quickly pump the brakes, especially in a way that may deplete the vacuum stored in a vehicle's brake booster if so equipped, or whether they apply the brakes in a manner corresponding to their desired deceleration. The National Highway Traffic Safety Administration (NHTSA) conducted a testing program to examine driver braking behavior in crash avoidance maneuvers. The data for those 245 test runs were reanalyzed, assessing patterns of brake pedal force application to determine whether pedal force variation was sufficient in magnitude and duration to reflect driver intent.
Technical Paper
2014-04-01
Masashi Terada, Takashi Kondo, Yukihiro Kunitake, Kunitomo Miyahara
Abstract In automobile development, steering vibrations caused by engine excitation force and suspension vibration input from the road surface are a problem. The conventional method of reducing vibrations and thereby securing marketability has been to dispose a dynamic damper inside the steering wheel. The resonance frequency of a steering system varies for each vehicle developed (as a result of the vehicle size, the arrangement of the stiff members of the vehicle body, and the like). As a result, the individual values of dynamic dampers that are used with vehicles must be adjusted for each developed vehicle type. To address this problem, we have developed a new structure in which, rather than using a conventional dynamic damper, we disposed a floating bush on the Supplemental Restraint System (SRS) module attachment section and used the SRS module itself as the weight for the dynamic damper. In this structure, the dynamic damper weight is approximately eight times greater than the conventional weight, the vibration reduction effect is enhanced, and the effective frequency range is widened.
Technical Paper
2014-04-01
Meng Huang
A disc-pad system is established to study impacts of surface topography on brake squeal from the perspective of statistical analysis. Firstly, surface topographies of brake disc and pad are precisely measured on the scale of micron and are statistically analyzed with a three-dimensional evaluation system. Secondly, the finite element model of brake disc and pad without surface topographies is created and verified through component free modal tests. Thereby the valid brake squeal model for complex modal analysis is built with ABAQUS. An effective method is developed to apply interface topographies to the smooth contact model, which consequently establishes sixty brake squeal models with topographies. Thirdly, impacts of surface topography on brake squeal are studied through comparison and statistical analysis of prediction results with and without topographies. The analysis manifest that topography amplitudes and evaluation index deviations of brake pad far exceed those of the disc, indicating the surface of brake pad is relatively much rougher.
Technical Paper
2014-04-01
Takehito Shiraishi, Yasuo Shimizu
In the automobile industries, weight reduction has been investigated to improve fuel efficiency together with reduction of CO2 emission. In such circumstance, it becomes necessity to make an electric power steering (EPS) more compact and lightweight. In this study, we aimed to have a smaller and lighter EPS gear size by focusing on an impact load caused at steering end. In order to increase the shock absorption energy without increase of stopper bush size, we propose new theory of impact energy absorption by not only spring function but also friction, and a new stopper bush was designed on the basis of the theory. The profile of the new stopper bush is cylinder form with wedge-shaped grooves, and when the new stopper bush is compressed by the end of rack and the gear housing at steering end, it enables to expand the external diameter and produce friction. In this study, we considered the durability in the proposed profile. In particular, the theoretical study was made on the effect due to sliding from the standpoint of the contact pressure and the sliding distance, and durability testing was carried out to check for the durability of the performance after predetermined operation time.
Technical Paper
2014-04-01
Shinichi Nishizawa, Takahiro Nakamura, Kazuo Furukawa, Senri Moriyama, Ryuichi Sato
In McPherson strut applications for automotive suspension systems, the desired coil spring reaction force vector (FLP: force line position) that minimizes damper friction and king pin moment is typically determined by Statics/Kinematics calculations. There is not a device available on the open market today which can mimic the coil spring reaction force vector within the suspension system. Such a programmable coil spring reaction force vector generator, named “Universal Spring”, was developed in 2003 (USPG2003), and was then improved in 2013 (USPG2013) from the standpoint of accuracy, durability and reliability. The device is actuated by six hydraulic cylinders constructing a Stewart platform type parallel mechanism. Accuracy of FLP generated by USPG2013 is 1.1mm at maximum in ϕ80mm area around strut axis. Using this modified device, the relationship between the spring reaction force vector and damper friction, as well as spring reaction force vector and king pin moment, can be experimentally studied to confirm vehicle characteristics without actually producing any prototype coil springs.
Technical Paper
2014-04-01
Amir Khajepour, Ankur Agrawal
A control algorithm is developed for active/semi-active suspensions which can provide more comfort and better handling simultaneously. A weighting parameter is tuned online which is derived from two components - slow and fast adaptation to assign weights to comfort and handling. After establishing through simulations that the proposed adaptive control algorithm can demonstrate a performance better than some controllers in prior-art, it is implemented on an actual vehicle (Cadillac STS) which is equipped with MR dampers and several sensors. The vehicle is tested on smooth and rough roads and over speed bumps.
Technical Paper
2014-04-01
Yosuke Tanaka, Yasuo Shimizu
This paper will discuss the stress reduction of the worm wheel for an electric power steering (EPS) system. The research discussed in this paper focused on the worm wheel, the EPS component that determines the maximum diameter of the system. If the stress of the worm wheel could be reduced without increasing in size, it would be possible to reduce the size of the worm wheel and EPS system. In order to reduce the stress of the worm wheel, the conventional design method has extended the line-of-action toward outside of the worm wheel to increase the contact ratio of the gears and these method lead to an increase in the outer diameter. In order to address this issue, past research proposes the basic concept to extend line-of-action toward the inside of the worm wheel. And this new meshing theory was named MUB (Meshing Under Base-circle) theory. In this paper, characteristics of meshing of the gear formed by MUB theory are determined in more detail. After that, an example of design guideline of the worm gear profile based on MUB theory is explained.
Technical Paper
2014-04-01
Sangzhi Zhu, Haiping Du, Nong Zhang, Lifu Wang
In this paper, a more sophisticated mathematical linear model for a roll-plane active hydraulically interconnected suspension (HIS) system was developed. Model parameters tuning were then carried out, which resulted in a model that is capable of producing rather accurate estimation of the system, with significant improvements over models built previously. For the verification of the new model, two simulations and corresponding experiments are conducted. Data comparisons between the simulations and experiments show high consistent responses of the model and the real system, which validated the robustness and accuracy of the new mathematical model. In this process, the characteristics of the pressure response and the rise time inside the actuators have been revealed due to the presence of the flow.
Technical Paper
2014-04-01
Christian Angrick, Sebastiaan van Putten, Günther Prokop
In investigation and development of road tires within passenger car development, temperature dependency of tire characteristics is often neglected. This research however explicitly focuses on investigation and identification of temperature dependency of tire characteristics and its interaction with other inner tire states. To this extent, a novel method using a thermographic camera for measurement of both tire core and surface temperature is used. On the basis of these measurements, the dependency of cornering stiffness, relaxation length and lateral coefficient of friction on either core or surface temperature is presented. Moreover, the effect of tire core temperature on inner pressure is investigated. By choice of appropriate operating conditions, the effects of temperature and inner pressure on tire characteristics is investigated separately. A mechanical-analytical analysis forms the basis for derivation of the relationship between material attributes and tire characteristics. Material measurements of a sample taken from the tire under investigation are performed utilizing a hydropulser test rig.
Technical Paper
2014-04-01
Sukhwan Cho, Rebecca Anne Bandy, John Ferris, Joerg Schlinkheider, Marc Wimmershoff
A Location-Aware Adaptive Vehicle Dynamics System (LAAVDS) is developed to assist the driver in maintaining vehicle handling capabilities through various driving maneuvers. An integral part of this System is an Intervention Strategy that uses a novel measure of handling capability, the Performance Margin, to assess the need to intervene. Through this strategy, the driver's commands are modulated to affect desired changes to the Performance Margin in a manner that is minimally intrusive to the driver's control authority. Real-time implementation requires the development of computationally efficient predictive vehicle models. This work develops one means to alter the future vehicle states: modulating the driver's brake commands. This control strategy must be considered in relationship to changes in the throttle commands. Three key elements of this strategy are developed in this work. An algorithm is developed to determine when to switch from a throttle-only control strategy to a braking strategy.
Technical Paper
2014-04-01
Masashi Tsushima, Eiichi Kitahara, Taichi Shiiba, Takumi Motosugi
The adoption of the electronic controlled steering systems with new technologies has been extended in recent years. They have interactions with other complex vehicle subsystems and it is a hard task for the vehicle developer to find the best solution from huge number of the combination of parameter settings with track tests. In order to improve the efficiency of the steering system development, the authors had developed a steering bench test method for steering system using a Hardware-In-the-Loop Simulation (HILS). In the steering HILS system, vehicle dynamics simulation and the tie rod axial force calculation are required at the same time in the real-time simulation environment. The accuracy of the tie rod axial force calculation is one of the key factors to reproduce the vehicle driving condition. But the calculation cannot be realized by a commercial software for the vehicle dynamics simulation. A multibody kinematics model of strut suspension was developed for the tie rod axial force calculation.
Technical Paper
2014-04-01
Andrew Pennycott, Leonardo De Novellis, Aldo Sorniotti, Patrick Gruber
The combination of continuously-acting high level controllers and control allocation techniques allows various driving modes to be made available to the driver. The driving modes modify the fundamental vehicle performance characteristics including the understeer characteristic and also enable varying emphasis to be placed on aspects such as tire slip and energy efficiency. In this study, control and wheel torque allocation techniques are used to produce three driving modes. Using simulation of an empirically validated model that incorporates the dynamics of the electric powertrains, the vehicle performance, longitudinal slip and power utilization during straight-ahead driving and cornering maneuvers under the different driving modes are compared. The three driving modes enable significant changes to the vehicle behavior to be induced, allowing the responsiveness of the car to the steering wheel inputs and the lateral acceleration limits to be varied according to the selected driving mode.
Technical Paper
2014-04-01
Haohua Hong, Lifu Wang, Minyi Zheng, Nong Zhang
This paper employs the motion-mode energy method (MEM) to investigate the effects of a roll-plane hydraulically interconnected suspension (HIS) system on vehicle body-wheel motion-mode energy distribution. A roll-plane HIS system can directly provide stiffness and damping to vehicle roll motion-mode, in addition to spring and shock absorbers in each wheel station. A four degree-of-freedom (DOF) roll-plane half-car model is employed for this study, which contains four body-wheel motion-modes, including body bounce mode, body roll mode, wheel bounce mode and wheel roll mode. For a half-car model, its dynamic energy contained in the relative motions between its body and wheels is a sum of the energy of these four motion-modes. Numerical examples and full-car experiments are used to illustrate the concept of the effects of HIS on motion-mode energy distribution. The obtained simulation results show that the installed HIS system is able to reduce the energy level in the body-dominated roll motion-mode, and it has negligible effect in the bounce mode.
Technical Paper
2014-04-01
Narayanan Kidambi, R. L. Harne, Yuji Fujii, Gregory M. Pietron, K. W. Wang
Dynamic vehicle loads play critical roles for automotive controls including battery management, transmission shift scheduling, distance-to-empty predictions, and various active safety systems. Accurate real-time estimation of vehicle loads such as those due to vehicle mass and road grade can thus improve safety, efficiency, and performance. While several estimation methods have been proposed in literature, none have seen widespread adoption in current vehicle technologies despite their potential to significantly improve automotive controls. To understand and bridge the gap between research development and wider adoption of real-time load estimation, this paper assesses the accuracy and performance of four estimation methods that predict vehicle mass and/or road grade. These include recursive least squares (RLS) with multiple forgetting factors; extended Kalman filtering (EKF); a dynamic grade observer (DGO); and a method developed by this research: parallel mass and grade (PMG) estimation using a longitudinal accelerometer.
Technical Paper
2014-04-01
Scott Varnhagen, Donald Margolis
The use of electric motors to independently control the torque of two or four wheels of a vehicle has the potential to significantly improve safety and handling. One virtue of electric motors is that their output torque can be accurately estimated. Using this known output torque, longitudinal tire force and coefficient of friction can be estimated via a controller output observer. This observer works by constructing a model of wheel dynamics, with longitudinal tire force as an unknown input quantity. A known wheel torque is input to the physical and modeled system and the resulting measured and predicted wheel speeds are compared. The error between the measured and predicted wheel speed is driven towards zero by a robust feedback controller. This controller modulates an estimate of longitudinal tire force used as an input by the wheel dynamics model. The resulting estimate of longitudinal tire force quickly converges towards the actual value with minimal computational expense. Using this estimate, a methodology for controlling tire slip ratio is presented.
Technical Paper
2014-04-01
Jianmin Dang, Hui Chen, Bolin Gao, Qi Li, Minhao Li, Takeshi Watanabe, Ryouhei Hayama, Liming Lou, Shirou Nakano
To overcome the shortcomings of subjective evaluation, there have been several studies to examine the correlations between subjective and objective evaluations of on-center steering feel, and some useful results are obtained. However, it is still not clear how to design the steering characteristic based on the correlations. In this paper, we propose a methodology of identifying the optimal on-center steering force characteristic based on the correlations between subjective and objective evaluations. Firstly, significant correlations between subjective and objective evaluations regarding on-center steering feel are established and verified. These verified correlations are then used to design the steering force characteristic. With desired ratings of the subjective evaluation items set as optimization goals, the ideal values of objective evaluation indices are obtained by use of an optimal design method. At last, the optimal steering force characteristic is designed based on the ideal objective indices.
Technical Paper
2014-04-01
Tao Sun, Yuping He, Jing Ren
To date, various control strategies based on linear vehicle models have been researched and developed for improving lateral stability of car-trailer (CT) systems. Is a linear-model-based controller applicable to active safety systems for CT systems under emergency operating conditions, such as an evasive maneuver at high lateral accelerations? In order to answer the question, the applicability of an active trailer differential braking (ATDB) controller designed using a linear CT model is tested and evaluated, while the controller being applied to a CT system represented by a linear and a nonlinear CT model. The current research leads to the following insightful findings: the ATDB controller designed using the linear model can effectively improve the lateral stability of CT systems under regular evasive maneuvers at low lateral accelerations, but the controller is not applicable to CT active safety systems under emergency evasive maneuvers at high lateral accelerations. The insightful findings resulted from the paper will provide valuable design guidelines for the development of active safety systems for CT systems.
Technical Paper
2014-04-01
Mario Hrgetic, Josko Deur, Vladimir Ivanovic, Eric Tseng
Abstract This paper presents the extended Kalman filter-based sideslip angle estimator design using a nonlinear 5DoF single-track vehicle dynamics model with stochastic modeling of tire forces. Lumped front and rear tire forces have been modeled as first-order random walk state variables. The proposed estimator is primarily designed for vehicle sideslip angle estimation; however it can also be used for estimation of tire forces and cornering stiffness. This estimator design does not rely on linearization of the tire force characteristics, it is robust against the variations of the tire parameters, and does not require the information on coefficient of friction. The estimator performance has been first analyzed by means of computer simulations using the 10DoF two-track vehicle dynamics model and underlying magic formula tire model, and then experimentally validated by using data sets recorded on a test vehicle.
Technical Paper
2014-04-01
Ibrahim A. Badiru
The automotive industry is one of the most competitive enterprises in the world. Customers face an ever-expanding number of entries in each market segment vying for their business. Sales price, brand image, marketing, etc. all play a role in purchase decisions, but the factor distinguishing products that consistently perform in the market place is the ability to satisfy the customer. Steering character plays a critical role in the customer driving experience and can be one of the most heavily debated topics during a new vehicle program. The proliferation of EPS steering systems now allows engineers to calibrate steering feel to almost any desired specification. This raises a key question: What subjective & objective characteristics satisfy customers in a particular market segment? Answering this question requires continued research to develop objective metrics correlated to subjective steering attributes and increased understanding of customer preferences for objective performance parameters.
Technical Paper
2014-04-01
Jeremy Kolansky, Amandeep Singh, Jill Goryca
Ride control of military vehicles is challenging due to varied terrain and mission requirements such as operating weight. Achieving top speeds on rough terrain is typically considered a key performance parameter, which is always constrained by ride discomfort. Many military vehicles using passive suspensions suffer with compromised performance due to single tuning solution. To further stretch the performance domain to achieving higher speeds on rough roads, semi-active suspensions may offer a wide range of damping possibilities under varying conditions. In this paper, various semi-active control strategies are examined, and improvements have been made, particularly, to the acceleration-driven damper (ADD) strategy to make the approach more robust for varying operating conditions. A seven degrees of freedom ride model and a quarter-car model were developed that were excited by a random road process input modeled using an auto-regressive time series model. The proposed strategy shows promise as a cost-effective solution to improve the ride of a military vehicle over multiple stochastic terrains considering variation in operating weight.
Technical Paper
2014-04-01
Toshiya Hirose, Masato Gokan, Nobuyo Kasuga, Toichi Sawada
Collision avoidance systems for rear-end collisions have been researched and developed. It is necessary to activate collision warnings and automatic braking systems with appropriate timing determined by a monitoring system of a driver's braking action. Although there are various systems to monitor driving behavior, this study aims to create a monitoring system using a driver model. This study was intended to construct a model of a driver's braking action with the Time Delay Neural Network (TDNN). An experimental scenario focuses on rear-end collisions on a highway, such as the driver of a host vehicle controlling the brake to avoid a collision into a leading vehicle in a stationary condition caused by a traffic jam. In order to examine the accuracy of the TDNN model, this study used four parameters: the number of learning, the number of neurons in the hidden layer, the sampling time with 0.01 second as a minimum value, and the number of the delay time. In addition, this study made a comparative review of the TDNN model and the Neural Network (NN) model to examine the accuracy of the TDNN model.
Technical Paper
2014-04-01
Alexey Vdovin, Lennart Lofdahl, Simone Sebben
There are a number of numerical and experimental studies of the aerodynamic performance of wheels that have been published. They show that wheels and wheel-housing flows are responsible for a substantial part of the total aerodynamic drag on passenger vehicles. Previous investigations have also shown that aerodynamic resistance moment acting on rotating wheels, sometimes referred to as ventilation resistance or ventilation torque is a significant contributor to the total aerodynamic resistance of the vehicle; therefore it should not be neglected when designing the wheel-housing area. This work presents a numerical study of the wheel ventilation resistance moment and factors that affect it, using computational fluid dynamics (CFD). It is demonstrated how pressure and shear forces acting on different rotating parts of the wheel affect the ventilation torque. It is also shown how a simple change of rim design can lead to a significant decrease in power consumption of the vehicle. A way of introducing ventilation torque into the driving resistance equation is discussed.
Viewing 211 to 240 of 9914

Filter

  • Article
    321
  • Book
    59
  • Collection
    22
  • Magazine
    702
  • Technical Paper
    7402
  • Standard
    1408
  • Article
    1408