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SAE International Journal of Vehicle Dynamics Stability and NVH
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Brake Squeal Prevention through Suspension Design and Adaptive Suspension

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Indian Institute of Technology Delhi, India-Shashank Saxena, Jayanta Kumar Dutt
  • Journal Article
  • 10-03-03-0011
Published 2019-09-03 by SAE International in United States
The brake squeal phenomenon has bothered automobile manufacturers for a long time. Although having no ill effects on the braking performance, the squeaky noise is often a nuisance and one of the major complaints of many customers. In order to design quality and noise-free automobiles, the brake squeal issue has to be permanently tackled. Many researchers have suggested shape optimization and additional damping of the disk as brake squeal control measures. Other methods proposed in the literature include the use of a different brake pad material or an anti-squeal paste. However, the effect of the type of brake pad suspension on brake squeal has not been studied. In this article, we demonstrate that the use of a 4-element viscoelastic support can prevent brake squeal for a vehicle speed of 5-200 kmph, which is the practical vehicle speed range. For a 2-element support, we have identified a suitable control parameter and proposed an efficient active control for squeal prevention based on that. A nondimensional analysis has been carried out so as to ensure that the results…
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Application of Optimal Control Method to Path Tracking Problem of Vehicle

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Weifang University, China-Yingjie Liu, Dawei Cui
  • Journal Article
  • 10-03-03-0014
Published 2019-08-26 by SAE International in United States
Path tracking is an essential stage for vehicle safety control. It is more newsworthy than ever in the automotive context and especially for autonomous vehicle. The study proposes an optimal control method for path tracking problem in inverse vehicle handling dynamics. The proposed method generates an expected trajectory which guarantees minimum clearance to the prescribed path by identifying the optimal steering torque input. Based on this purpose, the path tracking problem, which is treated as an optimal control problem, is then solved by local collocation method and mesh refinement. Finally, a real vehicle test is executed to verify the rationality of the proposed model and methodology. The results show that using control variables as a mesh refinement function can capture the dramatic changes in state variables, and the efficiency improvement is more significant as the number of the grid points increases. The study can help drivers easily identify safe lane-keeping trajectories and area.
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An Optical-Based Technique to Obtain Vibration Characteristics of Rotating Tires

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Kettering University, USA-Aakash Mange, Theresa Atkinson, Jennifer Bastiaan, Javad Baqersad
  • Journal Article
  • 10-03-03-0013
Published 2019-08-21 by SAE International in United States
The dynamic characteristics of tires are critical in the overall vibrations of vehicles because the tire-road interface is the only medium of energy transfer between the vehicle and the road surface. Obtaining the natural frequencies and mode shapes of the tire helps in improving the comfort of the passengers. The vibrational characteristics of structures are usually obtained by performing conventional impact hammer modal testing, in which the structure is excited with an impact hammer and the response of the structure under excitation is captured using accelerometers. However, this approach only provides the response of the structure at a few discrete locations, and it is challenging to use this procedure for rotating structures. Digital Image Correlation (DIC) helps in overcoming these challenges by providing the full-field response of the structure. Although there have been many experiments on tires, there are few published papers that investigate the full-field dynamics of rotating tires at high rotating speeds. In the current work, the Kettering University Formula SAE (FSAE) vehicle is loaded on a chassis dynamometer for the purpose of…
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Detection Method for Cavity Defects in Ballastless Track Structures of High-Speed Railways Based on Air-Coupled Ultrasonic Lamb Waves

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Shanghai University of Engineering and Technology, China-Zhu Wenfa, Shao Wei, Chen Xingjie, Meng Xiangzhen
Shanghai University, China-Zhang Haiyan
  • Journal Article
  • 10-03-02-0010
Published 2019-07-02 by SAE International in United States
This study proposes a method for the rapid detection and location of cavity defects in ballastless track structures of high-speed railways in service. First, the propagation of air-coupled ultrasonic Lamb waves in the ballastless track structure is studied. Theoretical calculation results show that the ultrasonic Lamb wave group velocity of the A2 mode in the track plate is 4000 m/s. Then, the excitation and reception methods of the air-coupled ultrasound are studied. Theoretical and experimental results show that the A2 mode Lamb wave can be generated by the 3.8° oblique incidence of the ballastless track structure. Finally, an experimental system for air-coupled ultrasonic testing is constructed. A pair of air-coupled ultrasonic probes is used to provide excitation and reception Lamb wave signals at an inclined angle of 3.8°, 20 mm away from the surface of the track plate, and 40 mm/step along the scanning direction. Experimental data indicate that interaction between the Lamb wave and cavity conforms to the energy leakage principle, and the amplitude of the Lamb wave increases with the increase in cavity…
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Impact of Dynamic Characteristics of Wheel-Rail Coupling on Rail Corrugation

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Shanghai University of Engineering Science, China-Xiaogang Gao, Anbin Wang, Xiaohan Gu, Wei Li
  • Journal Article
  • 10-03-02-0009
Published 2019-07-02 by SAE International in United States
To gain a better understanding of the characteristics of corrugation, including the development and propagation of corrugation, and impact of vehicle and track dynamics, a computational model was established, taking into account the nonlinearity of vehicle-track coupling. The model assumes a fixed train speed of 300 km/h and accounts for vertical interaction force components and rail wear effect. Site measurements were used to validate the numerical model. Computational results show that (1) Wheel polygonalisation corresponding to excitation frequency of 545-572 Hz was mainly attributed to track irregularity and uneven stiffness of under-rail supports, which in turn leads to vibration modes of the bogie and axle system in the frequency range of 500-600 Hz, aggregating wheel wear. (2) The peak response frequency of rail of the non-ballasted track coincides with the excitation frequency of wheel-rail coupling; the resonance results in larger wear amplitude of the rail. The track lateral pinned-pinned frequency at 540 Hz contributes to the propagation of rail corrugation. (3) With wheel-rail contact friction coefficient of 0.3, simulation results of track lateral pinned-pinned frequency…
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Development, Testing, and Assessment of a Kinematic Path-Following Model for Towing Vehicle Systems

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Mississippi State University, USA-Yucheng Liu, Dennison Iacomini, Brandon Powell, James Gafford, John Ball, Jian Shi
U.S. Army ERDC, USA-Collin Davenport
  • Journal Article
  • 10-03-01-0005
Published 2019-01-07 by SAE International in United States
A kinematic path-following model is developed based on an existing modeling framework established by the authors [1, 2] for prediction of the paths of towing vehicle systems. The presented path-following model determines the path of the towing vehicle using the vehicle’s speed and acceleration data collected by an inertial measurement unit (IMU). An Ackerman steering model was presented to calculate instantaneous directional angles and radii for each towed vehicle based on its geometric data and steering angle. In that model the off-tracking effect is properly captured. A 1:4 scale model for a towing vehicle system was built to test the developed steering model, and it was found that the angles and radii of the towing vehicle and each towed unit calculated using the Ackerman steering model agreed very well with those measured from the scale model. A hitch back model was then developed based on the steering model to simulate the continuous motion of the towing vehicle system and precisely follow its path. An algorithm was developed based on the hitch back model and programmed…
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Study of Riding Assist Control Enabling Self-Standing in Stationary State

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Honda R&D Co., Ltd., Japan-Makoto Araki, Kazushi Akimoto, Toru Takenaka
  • Journal Article
  • 10-03-01-0004
Published 2018-12-04 by SAE International in United States
In motorcycles, when they are traveling at medium to high speed, the roll stability is usually maintained by the restoration force generated by self-steering effect. However, when the vehicle is stationary or traveling in low speed, sufficient restoring force does not occur because some of the forces, such as centrifugal force, become small. In our study, we aimed at prototyping a motorcycle having a roll stability realized by a steering control when the vehicle is stationary or traveling in low speed. When we considered a mathematical control model to be applied, general models of four-degree-of-freedom had a critical inconvenience that the formulae include nonlinear second derivatives making them excessively complicated for deriving a practically applicable control method. Accordingly, we originally constructed a new control model which has equivalent two point masses (upper and lower from the vehicle’s center of gravity). With this model, the formula can be easily converted into mathematical expressions applicable for the actual control. From this model, we found that if the trail length has a negative value, only by steering control,…
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Tire Side Force Characteristics with the Coupling Effect of Vertical Load and Inflation Pressure

SAE International Journal of Vehicle Dynamics, Stability, and NVH

China Automotive Technology and Research Center Co., Ltd., China-Fei Li
GAC Automotive Engineering Institute, China-Chao Yang
  • Journal Article
  • 10-03-01-0002
Published 2018-11-09 by SAE International in United States
The tire vertical load and inflation pressure have great influence on tire steady- and non-steady-state characteristics and, consequently, on the vehicle handling and stability. The objective of this article is to reveal the coupling effect of tire vertical load and inflation pressure on tire characteristics and then introduce an improved UniTire side force model including such coupling effect through experimental and theoretical analysis. First, the influence of the tire vertical load and inflation pressure on the tire characteristics is presented through experimental analysis. Second, the theoretical tire cornering stiffness and lateral relaxation length model are introduced to study the underlying mechanism of the coupling effect. Then, an improved UniTire side force model including the coupling effect of tire vertical load and inflation pressure is derived. Finally, the proposed improved UniTire side force model is validated through tire steady-state and transient data. The coupling effect of tire vertical load and inflation pressure on tire cornering stiffness and lateral relaxation length is decided by the variation of the half length of tire contact patch and the carcass…
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A Heavy Tractor Semi-Trailer Stability Control Strategy Based on Electronic Pneumatic Braking System HIL Test

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Aptiv PLC, USA-Bin Li
State Key Laboratory of Automotive Simulation and Control, Jilin University, China-Hongyu Zheng, Yangyang Miao
  • Journal Article
  • 10-03-03-0016
Published 2019-10-15 by SAE International in United States
Aiming to improve the handling performance of heavy tractor semi-trailer during turning or changing lanes at high speed, a hierarchical structure controller is proposed and a hardware-in-the-loop (HIL) test bench of the electronic pneumatic braking system is developed to validate the proposed controller. In the upper controller, a Kalman filter observer based on the heavy tractor semi-trailer dynamic model is used to estimate the yaw rates and sideslip angles of the tractor and trailer. Simultaneously, a sliding mode direct yaw moment controller is developed, which takes the estimated yaw rates and sideslip angles and the reference values calculated by the three-degrees-of-freedom dynamic model of the heavy tractor semi-trailer as the control inputs. In the lower controller, the additional yaw moments of tractor and trailer are transformed into corresponding wheel braking forces according to the current steering characteristics. The HIL test bench of the electronic pneumatic braking system is built to verify the effectiveness of the strategy. Double lane-change maneuver, sinusoidal maneuver, and J-turn maneuver are selected as handling and stability test conditions. The LabView real-time…
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Nonlinear Iterative Optimization Process for Multichannel Remote Parameter Control

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Meng Li, Yong Zhang
  • Journal Article
  • 10-03-03-0015
Published 2019-10-14 by SAE International in United States
In this article, compared with traditional Remote Parameter Control (RPC), the iterative process is improved based on linear transfer function (TF) estimation of the nonlinear dynamic system. In the improved RPC, the iteration coefficient is designed according to the convergence condition of the nonlinear iterative process, so that the convergence level, convergence speed, and iteration stability could be improved. The difference between the traditional and the improved RPC iterative process is discussed, the RPC iterative process of the nonlinear system is analyzed, and channel decoupling for Multi-Input Multi-Output (MIMO) system based on eigen-decomposition of the system TF and linear TF estimation is introduced. It assumes that the eigenvector matrix of the system TF remains the same, and the linear TF in the iterative process is estimated and updated, which is used for iterative calculation. The method for iteration coefficient is designed according to the nonlinear system convergence condition of the iterative process. The whole theory is verified on a two-channel electrohydraulic servo system and a lightweight motorcycle. The optimization strategy can be used not only…