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SAE International Journal of Vehicle Dynamics Stability and NVH
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Development of an Empirical Spring Aid Model for Automotive Applications

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Kongsberg Automotive-Domingo Beltran
  • Journal Article
  • 10-02-02-0006
Published 2018-05-10 by SAE International in United States
Spring aids are used to provide additional stiffness at the end of bump travel, preventing metal to metal contact. Commonly they are represented by nonlinear stiffness depending on displacement; however the main drawback of this approach is that it does not show any hysteretic behavior, hence they do not produce realistic force predictions differentiating between loading and unloading and energy absorbed is not calculated. Although introducing damping as a function of velocity generates some hysteresis, it does not generate realistic results for quasi-static and dynamic events; and measured data proves that velocity does not have a significant influence in the width of the loop. An empiric model can be build combining nonlinear stiffness and viscous damping, as a function of velocity, and also adding an additional term accounting for structural damping. This structural damping, implemented similar to a friction element, is nonlinear depending on displacement and velocity; and it is capable of representing realistically the hysteresis present in the component behavior. The three terms work in parallel, stiffness and structural damping capture the amplitude dependency…
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A Robust Wheel Slip Control Design with Radius Dynamics Observer for EV

SAE International Journal of Vehicle Dynamics, Stability, and NVH

University of Saida-Kada Hartani, Mohamed Khalfaoui, Abdelkader Merah, Norediene Aouadj
  • Journal Article
  • 10-02-02-0009
Published 2018-06-18 by SAE International in United States
In order to improve the safety and dynamic performance of electric vehicles equipped with four in-wheel electric motors, and prevent the wheels from locking or slipping when braking or accelerating, a new longitudinal control strategy which combines ASR traction and ABS braking control is proposed using an observation algorithm of effective radius for four wheel of electric vehicle. Using the electric motor torques as the unique actuator signal sources, this combined ASR/ABS can act as acceleration slip regulation (ASR) by preventing the wheels from slipping during acceleration and as an antilock braking system (ABS) by preventing the wheels from getting locked during braking. A variation of effective radius of the wheel’s tire can have an incidence on the longitudinal and lateral control. Moreover, the wheel effective radius observer based on high order sliding mode approach using the information of the electric motor torques and the angular velocities is used in the combined ASR/ABS systems. First, adjusting the motor torque and based on Fuzzy logic control, the acceleration slip regulation (ASR) is designed to maintain the…
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Design of Adjustable Road Feeling Performance for Steering-by-Wire System

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Concordia University-Bin Li
Jilin University-Hongyu Zheng, Jian Zhou
  • Journal Article
  • 10-02-02-0008
Published 2018-06-18 by SAE International in United States
Since steering-by-wire (SBW) system decouples mechanical linkages between front tires and the steering wheel, the road feeling characteristics of SBW system can be designed flexibly to improve the driving experience. In this article, a road feeling system with adjustable performance is proposed based on integrating the elements of the steering wheel module and the steering actuator module of SBW system. In this system, the road feeling torque consists of a main toque and a tuning torque, which are deduced by parametric method. The main torque is to feed back the tire dynamics and road properties to the driver intuitively, and the tuning torque is designed as a compensation of the main torque to tune the road feeling performance. The parameters in the formula of road feeling torque are selected properly and the driver can get the preferred road feeling performance by tuning these parameters in the formula. Next, to obtain the desired road feeling characteristics for different drivers, the sensitivity of formula parameters is analyzed quantitatively according to objective evaluation indices for on-center handling. Then,…
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Active Suspension: Future Lessons from The Past

SAE International Journal of Vehicle Dynamics, Stability, and NVH

ZF Commercial Vehicle Technology-Daniel Eugene Williams
  • Journal Article
  • 10-02-02-0010
Published 2018-06-18 by SAE International in United States
Active suspension was a topic of great research interest near the end of last century. Ultimately broad bandwidth active systems were found to be too expensive in terms of both energy and financial cost. This past work, developing the ultimate vehicle suspension, has relevance for today’s vehicle designers working on more efficient and effective suspension systems for practical vehicles. From a control theorist’s perspective, it provides an interesting case study in the use of “practical” knowledge to allow “better” performance than predicted by theoretically optimal linear controllers. A brief history of active suspension will be introduced. Peter Wright, David Williams, and others at Lotus developed their Lotus modal control concept. In a parallel effort, Dean Karnopp presented the notion of inertial (Skyhook) damping. These concepts will be compared, the combination of these two distinctly different efforts will be discussed, and eventual vehicle results presented. Most of the contemporary literature treated active suspension as a theoretical vibration isolation problem, but handling improvements from active suspension were even more impressive. Handling and actual hardware considerations motivated a…
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Filled Rubber Isolator’s Constitutive Model and Application to Vehicle Multi-Body System Simulation: A Literature Review

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Ebco, Inc.-Peijun Xu
Huazhong University of Science and Technology-Xingxing Feng, Yunqing Zhang
  • Journal Article
  • 10-02-02-0007
Published 2018-06-05 by SAE International in United States
Rubber elements present highly nonlinear mechanical properties affected by frequency and amplitude of excitation, prestrain and temperature, etc. Finite element (FE) models and lumped parameter models can be distinguished in the development of constitutive models of rubbers. Based on the concept of overlay model, different kinds of viscoelastic, or frequency-dependent models, and elastoplastic/friction, or amplitude-dependent models, are compared in terms of their modelling approach, parameters identification process and applications. Prestrain-dependent models and temperature-dependent thermo-mechanical models are also reviewed, including some special models which are not based on the concept of the overlay model. Experimental and computational studies of cylindrical bushings subjected to coupled deformation modes are analyzed and discussed. It is the hope that this literature review work can help clarify and guide the future research and development direction about rubber constitutive modelling.
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