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Research on Trajectory Planning for Four-wheel Steering Autonomous Vehicle with V2V Communication

Jilin University-Fangwu Ma, Yucheng Shen, Jiahong Nie, Xiyu Li, Yu Yang, Jiawei Wang, Guanpu Wu
  • Technical Paper
  • 2020-01-0114
To be published on 2020-04-14 by SAE International in United States
Lane-changing is a typical traffic scene effecting on road traffic with high request for reliability, robustness and driving comfort to improve the road safety and transportation efficiency. The development and application of connected autonomous vehicles with V2V communication provides more advanced control strategies to research of lane-changing. Meanwhile, Four-wheel steering is an effective way to improve flexibility of vehicle. The front and rear wheels rotate in opposite direction to reduce the turning radius to improve the servo agility operation at the low speed while those rotate in same direction to reduce the probability of the slip accident to improve the stability at the high speed. Hence, this paper established Ackerman front-wheel steering with proportional rear-wheel steering vehicle dynamic model and quasi real lane-changing scenes to analyze the motion constraints of the vehicles. Then, the polynomial function and Sin function were used for the lane-changing trajectory planning and the extended rectangular vehicle model was established to get vehicle collision avoidance condition. Vehicle comfort requirements and lane-changing efficiency were used as the optimization variables of optimization function.…
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Acoustic characteristics prediction and optimization of wheel resonators with arbitrary section

SAIC Motor Corporation Limited-Yimin Sun, Junlei Mao
Tongji University-Rong Guo, Tiantian Mi
  • Technical Paper
  • 2020-01-0917
To be published on 2020-04-14 by SAE International in United States
Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal simulation and test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics. Combing the transmission loss prediction theory and particle swarm algorithm, the structure parameters of the wheel resonator are optimized. A remarkable attenuation of tire cavity resonance can be observed through test results.
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An Experimental Methodology for Measuring Resistance Forces of Light-Duty Vehicles under Real-World Conditions and the Impact on Fuel Consumption

Aristotle University of Thessaloniki-Dimitrios Komnos, Leonidas Ntziachristos
European Commission Joint Research-Georgios Fontaras, Jelica Pavlovic, Biagio Ciuffo
  • Technical Paper
  • 2020-01-0383
To be published on 2020-04-14 by SAE International in United States
A key element of any vehicle-certification test is the use of representative values for the vehicle resistance forces. In most certification procedures, including the WLTP recently adopted by the EU, the latter is achieved mainly through coast down tests. Subsequently, the resistance values measured are used for setting up the chassis-dyno resistances applied during the laboratory measurements. These reference values are obtained under controlled conditions, while a series of corrections are applied to make the test procedure more repeatable and reproducible. In real driving, the reference road loads are influenced by a series of factors leading to a divergence between the certified fuel consumption values, and the real-world ones. An approach of calculating representative road loads during on-road tests can help to obtain a clearer view of vehicle efficiency and quickly validate the officially declared road loads. This approach is crucial also for validating simulations and achieving better estimates of the actual fuel consumption, a requirement introduced by the new policy adopted in the EU. In this direction, a series of on-road experiments were conducted,…
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Impact of Rim Orientation on Road Vehicles Aerodynamics Simulations

Graz University of Technology-Wolfgang von der Linden, Günter Brenn
Magna Steyr Fahrzeugtechnik AG & Co KG-Gernot Bukovnik
  • Technical Paper
  • 2020-01-0674
To be published on 2020-04-14 by SAE International in United States
Aerodynamic CFD simulations in the automotive industry based on the steady-state RANS (Reynolds-averaged Navier–Stokes) approach typically utilize approximate numerical methods to account for rotating wheels. In these methods, the computational mesh representing the rim geometry remains stationary, and the influence of the wheel rotation on the air flow is modelled. As the rims are considered only in one fixed rotational position (chosen arbitrarily in most cases), the effects of the rim orientation on the aerodynamic simulation results are disregarded and remain unquantified. This paper presents a numerical sensitivity study to examine the impact of the rim orientation position on the aerodynamic parameters of a detailed production vehicle. The simulations are based on the steady-state RANS approach. These investigations are carried out for three rim geometries, and for simulation cases with stationary and rotating wheels for comparison, where the Moving Wall (MW) and the Moving Reference Frame (MRF) methods, as well as combinations of the two approaches are used to model the wheel rotation. For the test vehicle, alterations in the flow field, and subsequently an…
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Facility for Complete Characterization of Suspension Kinematic and Compliance Properties of Wheeled Military Vehicles

SEA, Ltd.-Dale Andreatta, Gary Heydinger, Anmol Sidhu, Scott Zagorski
  • Technical Paper
  • 2020-01-0175
To be published on 2020-04-14 by SAE International in United States
As part of their ongoing efforts to model and predict vehicle dynamic behavior, the US Army’s Ground Vehicle Systems Center procured a facility in two phases. The facility is called the Suspension Parameter Identification and Evaluation Rig (SPIdER) and has a capacity covering all of the military’s wheeled vehicles, with vehicle weights to 100,000 lbs (45,400 kg), up to 150 inches wide, with any number of axles. The initial phase had the ability to measure bounce and roll kinematic and compliance properties. The SPIdER is the companion machine to the Vehicle Inertia Parameter Measuring Device (VIPER) which measures the inertia properties of vehicles of similar size. In 2015, the final phase of the SPIdER was completed. This phase includes ground plane wheel pad motion so that lateral, longitudinal, and aligning moment compliance and kinematic properties can be measured. These capabilities greatly enhance the SPIdER’s features, giving it the ability for making complete suspension and steering system kinematic and compliance measurements. Horizontal forces and aligning moments can be applied up to the limits of tire slip.…
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Parametric Study of Reduced Span Side Tapering on a Simplified Model with Wheels

Jaguar Land Rover-Adrian Gaylard
Loughborough University-Max Varney, Martin Passmore, Ryan Swakeen
  • Technical Paper
  • 2020-01-0680
To be published on 2020-04-14 by SAE International in United States
Sports Utility Vehicles (SUVs) often have blunt rear end geometries for design aesthetics and practicality, however, such vehicles are potentially high drag. The application of tapering; typically applied to an entire edge of the base of the geometry is widely reported as a means of reducing drag, but in many cases this is not practical on real vehicles. In this study side tapers are applied to only part of the side edge of a simplified automotive geometry, to show the effects of practical implementations of tapers. The paper reports on a parametric study undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor model equipped with wheels. The aerodynamic effect of implementing partial side edge tapers is assessed from a full height taper to a 25% taper in both an upper and lower body configuration. These were investigated using force and moment coefficients, pressure measurements and planar particle image velocimetry (PIV). These geometries showed that the drag reductions are maximised with a 50% span, generating a vertically symmetric wake and less taper drag…
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Effect of Flange radius and width on the Fatigue Life of wheel hub under Cornering Loads

Mahindra & Mahindra Ltd.-Srikrishna Koduri, Durgaprasad Mohapatra, Suhas Kangde
  • Technical Paper
  • 2020-01-1232
To be published on 2020-04-14 by SAE International in United States
Automotive Wheel Hub is a safety critical component. Integrated Wheel hub design is improved from 1st generation to 3rd generation to meet the durability targets with less weight. Lateral loading is critical parameter for designing wheel hub. Cornering test is performed at vehicle level to evaluate wheel hub. Cornering test has combination of three types of tracks. In Wheel hub design, flange radius and flange width are two important design parameters to meet the durability life for cornering loads. We have considered the combination of different flange radius and flange width to understand the effect of these two parameters on wheel hub fatigue life. These three-wheel hubs are tested till failure and life scatter is plotted. Strain data is acquired at flange radius on wheel hub for all cornering test tracks. Using Wheel Force Transducers (WFT), Forces and moments are acquired at wheel center for all cornering test tracks. Duty cycle is derived from measured loads. FE model of Wheel end simulation contains Wheel hub, Wheel rim, Knuckle, drive shaft and wheel nut. FE Analysis…
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Bicycle Braking Performance Testing and Analysis

Momentum Engineering Corp.-Nicholas Famiglietti, Benjamin Nguyen, Edward Fatzinger, Jon Landerville
  • Technical Paper
  • 2020-01-0876
To be published on 2020-04-14 by SAE International in United States
The goal of this study was to determine the braking capabilities of different bicycle types, with different brake setups and applications. A variety of bicycles, including a mountain bike, beach cruiser, BMX bike, road bike, and commuter bike were used to perform brake-to-stop tests. Prior to brake testing, the bicycles were fully inspected, prepped, and documented. Details of the bicycles’ make, model, tires, wheels, brake setup, suspension setup, and preexisting damage were photographed and recorded. The standardized brake testing procedure consisted of rear only brake application and both front and rear brake application. In order to maintain brake application consistency, a single rider performed all series of the skid/brake tests at the same location, on dry asphalt. The tests were performed at an initial velocity of 9 – 20 mph. For each test, the rider accelerated to the test speed and applied maximum braking effort while maintaining a natural upright position to reduce lean. The tests were performed on a painted grid for visibility purposed in measuring skid lengths and post-test video analysis. The bicycle…
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Automotive Wheel Metamodeling using Response Surface Methodology (RSM) Technique

FCA Engineering India Pvt. Ltd.-Gurumoorthy S, Muthukumar Arunachalam, Sundaravadivelu Mohan
FCA US LLC-Thomas Oery
  • Technical Paper
  • 2020-01-1234
To be published on 2020-04-14 by SAE International in United States
Computational cost plays a major role in the performance of scientific and engineering simulation. This in turn makes the virtual validation process complex and time consuming. In the simulation process, achievement of appropriate level of accurate models as close as physical testing is the root for increase in the computational cost. During preliminary phase of product development, it is difficult to identify the appropriate size, shape and other parameters of the component and they will undergo several modifications in concept and other stages. An approximation model called metamodel or surrogate model has developed for reducing these effects and minimizing the computational cost. Metamodel can be used in the place of actual simulation models. Metamodel can be an algorithm or a mathematical relation representing the relations between input and output parameters. The scope of this paper is to generate approximate models (metamodels) for the automotive wheel with help of response surface methodology (RSM) using Isight commercial tool and to arrive at the optimum shape, size and weight of the wheels by considering all necessary loading conditions.…
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Predication & Correlation of Bearing Preload With Rotational Torque In Wheel End Bearing System

VE Commercial Vehicles, Ltd.-Suchit Sharma, Prasad S. Warwandkar
  • Technical Paper
  • 2020-01-0951
To be published on 2020-04-14 by SAE International in United States
Wheel end bearing is one of the critical components of the vehicle as it shares the loads & wheels rotate on it.In wheel end ,taper roller bearings are used .This would help to withstand both vertical & lateral loads imparted during cornering. Also taper roller bearings are used in pair of two so that overall impact of lateral forces during straight running would be nullified. In wheel end bearing systems, 02 bearings are kept at distance w.r.t to each other based on position of load line & would share the total portion of load accordingly. Also life of bearings is dependent on whether the bearings are packaged & operating in play or preload. This paper focuses on various aspects of bearings life & how it vary with respect to Play & Preload. Also a methodology is developed to measure the overall preload of bearing system. Two different bearing systems one with distance piece & second without distance piece is considered. Stiffness of bearings & distance piece are measured out at different loads. Considering these stiffness,…