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Unsettled Issues in Balancing Virtual, Closed-Course, and Public-Road Testing of Automated Driving Systems

Silicon Valley Mobility-Sven Beiker
  • Research Report
  • EPR2019011
To be published on 2019-12-20 by SAE International in United States
This SAE EDGE™ Research Report identifies key unsettled issues of interest to the automotive industry regarding the challenges of determining the optimal balance for testing automated driving systems (ADS). Three main issues are outlined that merit immediate interest: First, determining what kind of testing an ADS needs before it is ready to go on the road; Second, the current, optimal, and realistic balance of simulation testing and real-world testing; Third, the challenges of sharing data in the industry. SAE EDGE™ Research Reports are preliminary investigations of new technologies. The three technical issues identified in this report need to be discussed in greater depth with the aims of, first, clarifying the scope of the industry-wide alignment needed, second, prioritizing the issues requiring resolution, and, third, creating a plan to generate the necessary frameworks, practices, and protocols. NOTE: SAE EDGE™ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies of interest to the mobility industry. The goal of SAE EDGE™ Research Reports is to stimulate discussion and work in the…
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Unsettled Issues in Determining Appropriate Modeling Fidelity for Automated Driving Systems Simulation

Silicon Valley Mobility-Sven Beiker
  • Research Report
  • EPR2019007
Published 2019-12-06 by SAE International in United States
This SAE EDGE™ Research Report identifies key unsettled issues of interest to the automotive industry regarding the challenges of achieving optimal model fidelity for developing, validating, and verifying vehicles capable of automated driving. Three main issues are outlined that merit immediate interest:First, assuring that simulation models represent their real-world counterparts, how to quantify simulation model fidelity, and how to assess system risk.Second, developing a universal simulation model interface and language for verifying, simulating, and calibrating automated driving sensors.Third, characterizing and determining the different requirements for sensor, vehicle, environment, and human driver models.SAE EDGE™ Research Reports are preliminary investigations of new technologies. The three technical issues identified in this report need to be discussed in greater depth with the aims of, first, clarifying the scope of the industry-wide alignment needed; second, prioritizing the issues requiring resolution; and, third, creating a plan to generate the necessary frameworks, practices, and protocols.NOTE: SAE EDGE™ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies of interest to the mobility industry. The goal of…
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Modelling and Simulation of Vehicle Suspension System with Variable Stiffness Using Quasi-zero Stiffness Mechanism

SAE International Journal of Vehicle Dynamics, Stability, and NVH

University of Petroleum and Energy Studies, India-Mohit Saini
  • Journal Article
  • 10-04-01-0003
Published 2019-12-02 by SAE International in United States
The dynamics and comfort of a vehicle closely depends on the stiffness of its suspension system. The suspension system of a vehicle always had to trade-off between comfort and performance of a vehicle; since for comfort a softer suspension is preferred which in turn decreases the aerodynamics and cornering performance and increases the ride height of the vehicle; whereas in stiffer suspension the ride height can be lowered, but forces due to bumps are transferred all the way up to the drivers cabin. This article aims to design a vehicle suspension model with variable stiffness using quasi-zero stiffness (QZS) mechanism and study its force-displacement characteristics and minimize the fundamental stiffness of the suspension system. The model developed uses the principle of negative stiffness to achieve low stiffness for the softer suspension system. The mechanism designed comprises of a pushrod suspension system with three parallel springs attached to one end of the rocker arm, one primary coil spring is mounted perpendicular to the rocker arm and the other two secondary plate springs are attached to the…
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Electronic Differential Control of Rear-Wheel Independent-Drive Electric Vehicle

SAE International Journal of Vehicle Dynamics, Stability, and NVH

China-Hang Yun
Jiangsu University, China-Ren He
  • Journal Article
  • 10-04-01-0004
Published 2019-12-02 by SAE International in United States
To track desired slip ratios and desired longitudinal speeds at the centers of driving wheels in the curve, this article proposes a hierarchical structured electronic differential control (EDC) of rear-wheel independent-drive electric vehicle (EV). In the high-level control, a fuzzy algorithm-based coefficient is computed according to the driver’s emotional intention of acceleration. The fuzzy algorithm-based coefficient is used to correct the desired driving torque of vehicle transmitting to the medium-level control. In the medium-level control, an optimization algorithm is developed to allocate the desired torques with requirement of as much accurate yaw moment as possible by the desired driving torque of the vehicle and yaw moment. And the desired longitudinal speeds at the centers of the rear left and right wheels are corrected twice, respectively, by Ackermann steering principle, considering the slip angle of the wheel and yaw moment. Based on the desired torques and desired longitudinal speeds at the centers of the rear left and right wheels from the medium-level control, desired slip ratios and desired angular speeds of the rear left and right…
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Stall Mitigation and Lift Enhancement of NACA 0012 with Triangle-Shaped Surface Protrusion at a Reynolds Number of 105

SAE International Journal of Aerospace

University of Petroleum and Energy Studies, India-Aslesha Bodavula, Rajesh Yadav, Ugur Guven
  • Journal Article
  • 01-12-02-0007
Published 2019-11-22 by SAE International in United States
Transient numerical simulations are conducted over a NACA 0012 airfoil with triangular protrusions at a Reynolds number (Re) of 100000 using the γ-Reθ transition Shear Stress Transport (SST) turbulence model. Protrusions of heights 0.5%c, 1%c, and 2%c are placed at one of the three locations, viz, the leading edge (LE), 5%c on the suction surface, and 5%c on the pressure surface, while the angle of attack (AOA) is varied between 0° and 20°. Results obtained from the time-averaged solution of the unsteady Navier-Stokes equation indicate that the smaller protrusion placed at 5%c on the suction surface improves the post-stall lift coefficient by up to 59%, without altering the pre-stall characteristics. The improvement in time-averaged lift coefficients comes with enhanced flow unsteadiness due to vigorous vortex shedding. For a given protrusion height, the vortex shedding frequency decreases as the AOA is increased, while the amplitude of fluctuations in lift coefficient increases as the protrusion height is increased or as the AOA is increased. Nevertheless, mitigation of static stall phenomena is observed for most configurations investigated, and…
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To establish the correlation in between Computer Aided Engineering & physical testing of automotive parts returnable case (Stacktainer).

International Centre for Automotive Technology-Ashish Singh
  • Technical Paper
  • 2019-28-2569
Published 2019-11-21 by SAE International in United States
Automotive returnable cases (Stacktainers) are being used to transport the automotive parts through surface & seaways. No automotive manufacturer wants to spend money on woods, paper & cardboard again and again, it`s better to pay once for robust & reusable cases. these provide better protection to parts from its manufacturing to assembly line of vehicle. While transporting, any kind of crack or failure of returnable cases may lead to loss of money, human & time. To ensure the safety, these pallets have to be validated for vibrations coming from surface irregularities, sea waves & load due to stacking of cases one above other. The objective of this study is to establish a correlation in between the physical testing & simulation in Computer added Engineering (CAE) of automotive returnable case (Stacktainers). There are different types of tests considered to validate the returnable case, rough road evaluation, Multi-axial Vibration & strength evaluation. After conducting the physical test & CAE simulation, a correlation & confidence level up to 90% is established.
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A Machine Learning based Multi-objective Multidisciplinary Design Optimization (MMDO) for Lightweighting the Automotive Structures

Mahindra and Mahindra, Ltd.-Ranga Srinivas Gunti
  • Technical Paper
  • 2019-28-2424
Published 2019-11-21 by SAE International in United States
The present work involves Machine Learning (ML) based Multi-objective Multidisciplinary Design Optimization (MMDO) for lightweighting the automotive structures. The challenge in deployment of MMDO algorithms in solving real-world automotive structural design problems is the enormous time involved in solving full vehicle finite element models that involve large number of design variables and multiple performance constraints pertaining to vehicle dynamics, durability, crash and NVH domains. With the availability of powerful workstations and using the advanced Computer Aided Engineering (CAE) tools, it has become possible to generate huge sets of simulation data pertaining to multiple domains. In the present work, lightweigting of the vehicle structure is achieved, considered the vehicular hardpoint locations and the gages of the vehicle structures as the design variables and performance parameters pertaining to vehicle dynamics, structural durability, front-end intrusions during an IIHS offset impact test and the modal frequencies of few critical structural members as the constraint variables. Artificial Neural Networks (ANN) based algorithms were used for developing the predictive models of various performance parameters. The predictive models were then used to…
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Ride-Comfort Analysis for Commercial Truck Using MATLAB Simulink

ARAI Academy-Sarnab Debnath
Automotive Research Association of India-Mohammad Rafiq Agrewale
  • Technical Paper
  • 2019-28-2428
Published 2019-11-21 by SAE International in United States
Ride Comfort forms a core design aspect for suspension and is to be considered as primary requirement for vehicle performance in terms of drivability and uptime of passenger. Maintaining a balance between ride comfort and handling poses a major challenge to finalize the suspension specifications. The objective of this project it to perform ride- comfort analysis for a commercial truck using MATLAB Simulink. First, benchmarking was carried out on a 4x2 commercial truck and the physical parameters were obtained. Further, a mathematical model is developed using MATLAB Simulink R2015a and acceleration- time data is collected. An experimentation was carried out on the truck at speeds of 20 kmph, 30 kmph, 40 kmph and 50 kmph over a single hump to obtain actual acceleration time domain data. The model is then correlated with actual test over a single hump. This is followed by running the vehicle on Class A, B & C road profiles to account for random vibrations. Similarly, a simulation is done on MATLAB Simulink and a correlation is established between simulated and actual…
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Body Structure Strength Of Sleeper Coaches During Rollover Test As Per AIS 119

International Centre for Automotive Technology-Gopal Singh Rathore
  • Technical Paper
  • 2019-28-2567
Published 2019-11-21 by SAE International in United States
Bus passenger safety has always been a concern considering various impacts like side impact, front impact, rollover etc. happening in real life scenarios. Various standards have been formulated for simulating these conditions and with respect to rollover, standards like ECE-R66 are being used to understand the superstructure strength. In India, we have AIS-052 (bus body code) and AIS-031 specific for bus rollover testing. AIS-119 has been published for rollover testing of sleeper coaches with modifications in the survival space creation in sleeper coaches for berths. With physical testing being more expensive, CAE simulations are being considered as vital option which also helps in design modification in a lesser time. This paper discusses the scope of numerical simulation of sleeper coach rollover using an explicit dynamic solver RADIOSS to understand the structure deformations, survival space clearances/intrusions. The paper will describe the procedure for the numerical simulation starting from the CAD development, geometry clean up, meshing techniques, element formulations, CG measurement, input deck set up till the post processing of results. In order to validate the numerical…
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Multi body dynamic simulation of tyre traction trailer

International Centre for Automotive Technology-Gopal Singh Rathore
  • Technical Paper
  • 2019-28-2430
Published 2019-11-21 by SAE International in United States
Tyre Traction Trailer is a device designed to find the Peak Brake co-efficient of C2 and C3 tyre as per ECE R117. The trailer is towed by the truck and is braked suddenly to evaluate braking co-efficient of specimen tyre. It is a single wheel trailer equipped with load cell to capture tire loads (Normal and longitudinal)while braking. Traction Trailer is modelled in MSC Adams and rigid body simulation is carried out for static stability of the system. Dynamic simulations were performed to understand locking of wheels during braking. Body frame was further modelled as flex body to perform structural analysis of the frame. The paper contains stress and deformation plots of trailer Structure under various loading conditions, change in Centre of gravity, weight transfer and forces on springs during braking and cornering, plots of tractive and normal load on tyre during braking.