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Alleviating the Magnetic Effects on Magnetometers using Vehicle Kinematics for Yaw Estimation for Autonomous Ground Vehicles

Michigan Technological University-Ahammad Basha Dudekula, Jeffrey D. Naber
  • Technical Paper
  • 2020-01-1025
To be published on 2020-04-14 by SAE International in United States
Autonomous vehicle operation is dependent upon accurate position estimation and thus a major concern of implementing the autonomous navigation is obtaining robust and accurate data from sensors. This is especially true, in case of Inertial Measurement Unit (IMU) sensor data. The IMU consists of a 3-axis gyro, 3-axis accelerometer, and 3-axis magnetometer. The IMU provides vehicle orientation in 3D space in terms of yaw, roll and pitch. Out of which, yaw is a major parameter to control the ground vehicle’s lateral position during navigation. The accelerometer is responsible for attitude (roll-pitch) estimates and magnetometer is responsible for yaw estimates. However, the magnetometer is prone to environmental magnetic disturbances which induce errors in the measurement. The present work focuses on alleviating magnetic disturbances for ground vehicles by fusing the vehicle kinematics information with IMU senor in an Extended Kalman filter (EKF) with the vehicle orientation represented using Quaternions. In addition, the error in rate measurements from gyro sensor gets accumulated as the time progress which results in drift in rate measurements and thus affecting the vehicle…
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Quantification of Clamp Loss and Subsequent Loosening of Automotive Hub-Knuckle Joints under Time-Varying Proving Ground Loading

FCA US LLC-Sandip Datta, Parag Nittur
  • Technical Paper
  • 2020-01-0181
To be published on 2020-04-14 by SAE International in United States
Threaded fasteners or bolted joints are used extensively in automotive assemblies. There are standard procedures to evaluate joint performance under block cycles or road loads. The deciding load case for such joint design is slippage analysis of the joint.There are studies done to evaluate the theoretical and experimental behavior of these joints. There are different ways of understanding the interaction between the bolt and the nut under different loading scenarios. However, none have provided a satisfactory method of quantifying bolt loosening or loss of clamp load under cyclic loading, where no slippage is observed.Under varying loads, initial relaxation of the joint is followed by a loss of clamping load. Below a critical value, complete loss of clamping load progresses very rapidly and this results in a loose joint. The loss of clamping load below the critical value happens at a transition stage when both elastic deformations of the bolt as well as external moments contribute to rapid loosening.This study provides an overall understanding of geometric parameters that contribute to sudden loss of clamping load and…
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Experimentation for Design Improvements for Coil Spring in the Independent Suspension

Automann Inc.-Viraj Dave
Kettering University-Yaomin Dong
  • Technical Paper
  • 2020-01-0503
To be published on 2020-04-14 by SAE International in United States
The objective of this project is to analyze potential design changes that can improve the performance of helical spring in an independent suspension. The performance of the helical spring was based upon the result measure of maximum value of stress acting on it and the amount displacement caused when the spring undergoes loading. The design changes in the spring were limited to coil cross section, spring diameter (constant & variable), pitch and length of the spring. The project was divided into Stage I & Stage II. For Stage I, using all the possible combinations of these design parameters, linear stress analysis was performed on different spring designs and their Stress and displacement results were evaluated. Based on the results, the spring designs were classified as over designed or under designed springs. Then in Stage II, it was checked if the under designed springs can be optimized and classified according to a relevant application of the vehicles (racing cars or luxurious cars).The driving factor for this project was the amount of research that has taken place…
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An Interval Analysis and Optimization Method for Generated Axial Force of Automotive Drive Shaft Systems

South China University of Technology-Huayuan Feng, Subhash Rakheja
  • Technical Paper
  • 2020-01-0918
To be published on 2020-04-14 by SAE International in United States
To study the generated axial force (GAF) of the drive shaft system more accurately and effectively, this paper introduces the interval uncertainty into the research focusing on the GAF. Firstly, an interval uncertainty model for calculating the GAF is proposed based on the Chebyshev polynomials and an analytical model of the GAF. The input torque, the articulation angle, the rotation angle of the drive shaft system, the pitch circle radius (PCR) of the tripod joint and the friction coefficient are regarded as interval variables. Secondly, the upper and lower bounds of the proposed GAF model under interval uncertainty parameters are calculated quickly with the vertex method. Then the interval uncertainty optimization of the GAF under uncertainty parameters is performed. The upper bound of the response interval of the GAF is taken as the optimization object. Finally, the proposed model is verified by experiments, while the interval uncertainty analysis and optimization of the GAF are carried out through a numerical example.
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SUV Kinematics during a Steer-Induced Rollover Resolved Using Consumer-Grade Video, Laser Scans and Match-Moving Techniques

MEA Forensic Engineers & Scientists-Cole R. Young, David J. King, Gunter P. Siegmund
  • Technical Paper
  • 2020-01-0642
To be published on 2020-04-14 by SAE International in United States
Rollover crashes are complex events that generate motions in all six degrees of freedom (6DOF). Directly quantifying the angular rotations from video can be difficult and vehicle orientation as a function of time is often not reported for staged rollover crashes. Our goal was to evaluate the ability of using a match-moving technique and consumer-grade video cameras to quantify the roll, pitch and yaw angles and angular velocities of a rollover crash. We staged a steer-induced rollover of an SUV at 106 km/h. The vehicle was fitted with tri-axial accelerometers and angular rate sensors, and five consumer-grade video cameras (2 on tripods, 2 on drones, 1 handheld, ~30 fps) captured the event. Roll, pitch and yaw angles were determined from the video using specialized software. We then compared the vehicle orientation angles from the video data to the integrated angular rate data measured by onboard sensors, and also compared the angular rates from the differentiated video data to the angular rates measured directly by the sensors. We found that both methods of measuring the 3D…
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new

Residual Aligning Moment Test

Highway Tire Committee
  • Ground Vehicle Standard
  • J1988_202003
  • Current
Published 2020-03-11 by SAE International in United States
This SAE Recommended Practice describes the determination of tire pull force properties for an uninclined tire (SAE J670e) on a laboratory flat surface tire force and moment machine. It is suitable for accurately determining pull forces and residual aligning moments for passenger and light-truck tires. These properties are important determinants of vehicle trim (See section 2.1.2). They describe steady-state, free-rolling pull effects ascribable to tires. The test method described in this document is suitable for comparative evaluation of tires for research and development purposes. The method is also suitable for modeling when followed carefully.
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On Shedding Frequency and Aerodynamic Characteristics of a Rotating Wire-Wrapped Cylinder

California State University-Long Beach-Hamid R. Rahai, Jeremy Bonifacio, Assma Begum, Komal Gada
  • Technical Paper
  • 2020-01-0028
Published 2020-03-10 by SAE International in United States
Numerical and experimental investigations of shedding frequency of rotating smooth and wire-wrapped cylinders, placed in steady flow have been performed. The freestream mean velocity was 10 m/sec. and for the numerical investigations, the smooth cylinder diameter was 5 cm, which corresponds to an approximate Reynolds number based on cylinder’s diameter of 3.2x104. The wire-wrapped cylinder had a wire diameter of 5 mm and the ratios of pitch spacing to the cylinder diameter, p/D, was 1.0. The cylinder length to diameter ratio was 20. The rotation rates (λ) were 0.5 and 2.0. To obtain the shedding frequency, numerical probes were placed at 3D downstream, 0.5 D above the centerline, and at 0.5D, spaced along the spanwise direction and the shedding frequencies were obtained from spectra of the axial velocity. Results indicate that the lift for the wire-wrapped cylinder is nearly 150% of that of the smooth cylinder, however, it has a higher drag force. Details of the flow indicate wire-wrapping reduces spanwise coherency and increases the phase angle of vortices, resulting in increased lift. Experimental results…
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Measurement Uncertainty and Consumer Risk

E-25 General Standards for Aerospace and Propulsion Systems
  • Aerospace Standard
  • AIR6553
  • Current
Published 2020-02-03 by SAE International in United States
This document addresses measurement uncertainty and consumer risk as they relate to AS8879 thread inspection. It describes the rationale, theory and methodology used to generate the technical content of the AS5870. The document describes how to calculate measurement consumer risk. It documents all of the calculation methods which industry employs today to calculate what is commonly called measurement uncertainty (Appendices A, B, C, D, E and F). These, in turn, are used to calculate measurement uncertainty ratios which are required inputs to calculate measurement consumer risk. Users of this document can apply the information described herein for the evaluation of the capability of their measurements based on the measurement consumer risk. It involves the analysis of the measurement (product) distribution and biases of both the product and measurement system distributions. It protects the consumer from the worst case distribution results.
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Thread Inspection Practices

E-25 General Standards for Aerospace and Propulsion Systems
  • Aerospace Standard
  • AS5870
  • Current
Published 2020-02-03 by SAE International in United States
This document addresses AS8879 thread inspection issues relating to selection, usage and capability of gages. It addresses the selection of calibrated measurement gages, the need for defined quality metrics, the methodology of determining the appropriate guardband factors, and the minimum inspection requirements for single element pitch diameter gages. Users of this document shall apply the information described herein for the evaluation of the capability of their measurements based on the measurement consumer risk. It involves the analysis of the measurement (product) distribution and biases of both the product and measurement system distributions. It protects the consumer from the worst case distribution results. A whitepaper has been developed to provide supporting documentation and the rationale used in the development of this standard. This whitepaper will be published by the SAE as an Aerospace Information Report (AIR6553). This document recommends the use of ASME B1.2 “Gages and Gaging for Unified Inch Screw Threads” or IFI 301 “Gage Calibration Requirements and Procedures for Thread Gages” as guides for establishing the minimum calibration requirements for all types of thread…
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Pinpointing Consumption “Sweet Spot” Makes Formation Flight More Fuel-Efficient

  • Magazine Article
  • TBMG-35825
Published 2020-01-01 by Tech Briefs Media Group in United States

Formation flying — when one aircraft flies behind another — reduces drag and results in improved fuel consumption in the trailing vehicle; however, no sensor currently exists that directly measures drag. Instead, pilots rely on fuel flow measurements or induced aircraft moments — roll, pitch, and yaw — to estimate the best location within a leading vehicle's wave vortex. Fuel flow alone is a lagging drag estimate, which leads to inaccurate estimates. Aircraft moments alone also do not sufficiently indicate the best location for the trailing aircraft.