Determination of Road Load Coefficients with Smartphone Accelerometers

Günter Bischof; Felix Mayrhofer; Domenic Mönnich; Christian J. Steinmann

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Conference: 2023 ASEE Annual Conference & Exposition
Location: Baltimore , Maryland
Publication Date: June 25, 2023
Start Date: June 25, 2023
End Date: June 28, 2023
Conference Session: Student Projects in Physics Education, Engineering Physics and Physics Division (EP2D) Technical Session 2
Tagged Division: Engineering Physics and Physics Division (EP2D)
Page Count: 16
DOI: 10.18260/1-2--43015
Permanent URL: https://peer.asee.org/43015
Download Count: 108

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Paper Authors

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Günter Bischof Joanneum University of Applied Sciences, Austria

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Günter Bischof is currently an associate professor at Joanneum University of Applied Sciences and teaches engineering and applied mathematics.

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Felix Mayrhofer Joanneum University of Applied Sciences, Austria

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Felix Mayrhofer is currently studying Automotive Engineering at the University of Applied Sciences Joanneum Graz. When he has finished his studies, he wants to work as an Vehicle Dynamics Engineer.

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Domenic Mönnich Joanneum University of Applied Sciences, Austria

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Domenic Mönnich is currently studying Automotive Engineering at the University of Applied Sciences Joanneum Graz. After completion of his studies, he aspires to work in the field of research and development.

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Christian J. Steinmann Joanneum University of Applied Sciences, Austria

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Christian Steinmann has an engineer degree in mathematics from the Technical University Graz, where he focused on software quality and software development process assessment and improvement. He is manager of HM&S IT-Consulting and provides services for SPiCE/ISO 15504 and CMMI for development as a SEI-certified instructor. He performed more than 100 process assessments in software development departments for different companies in the finance, insurance, research, automotive, and automation sector. Currently, his main occupation is a consulting project for process improvement for safety related embedded software development for an automobile manufacturer. On Fridays, he is teaching computer science introductory and programming courses at Joanneum University of Applied Sciences in Graz, Austria.

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Abstract

Due to the integrated sensors, smartphone owners carry not only handy communication tools but also fully-fledged data acquisition and measurement systems in miniature form in their pockets. The measured data can be transferred quickly and easily to laptops or desktop PCs, where they are then available for further processing. Consequently, smartphones can enrich physics and engineering education in many ways, as they enable low-threshold access to physical measurement methods. In order to make use of this possibility, undergraduate student research projects with measuring tasks were initiated. One of them was the determination of the rolling and aerodynamic drag coefficients of model vehicles by using the accelerometers of their smartphones. The coastdown technique should be used, in which the vehicle is accelerated to a specified speed, shifted into neutral and allowed to decelerate freely. The time rate of change of its velocity is proportional to the total resistive force, which is assumed to consist of a speed-independent rolling resistance and an air resistance proportional to the square of the vehicle's speed. A smartphone attached to the model vehicle provides the time-dependent acceleration data, which is usually noisy and needs to be smoothed. The vehicle velocity, on the other hand, can be obtained from the acceleration data by numerical integration. By plotting the vehicle acceleration on the abscissa and the velocity square on the ordinate in a coordinate system for the coasting process, a straight line can be fitted. From the slope of this straight line, the aerodynamic drag coefficient can be derived, and its intersection with the ordinate provides information on the rolling resistance coefficient. Three teams of three or four students each worked simultaneously and competitively on that project. They independently conducted experiments and developed computer programs for the visualization of the data and evaluation of the measurements. In this paper, the theoretical background, the approach to the problem and the outcome of the undergraduate student projects are presented and discussed.

Citation
Format

Bischof, G., & Mayrhofer, F., & Mönnich, D., & Steinmann, C. J. (2023, June), Determination of Road Load Coefficients with Smartphone Accelerometers Paper presented at 2023 ASEE Annual Conference & Exposition, Baltimore , Maryland. 10.18260/1-2--43015

TY - CPAPER
AB - Due to the integrated sensors, smartphone owners carry not only handy communication tools but also fully-fledged data acquisition and measurement systems in miniature form in their pockets. The measured data can be transferred quickly and easily to laptops or desktop PCs, where they are then available for further processing. Consequently, smartphones can enrich physics and engineering education in many ways, as they enable low-threshold access to physical measurement methods.
In order to make use of this possibility, undergraduate student research projects with measuring tasks were initiated. One of them was the determination of the rolling and aerodynamic drag coefficients of model vehicles by using the accelerometers of their smartphones. The coastdown technique should be used, in which the vehicle is accelerated to a specified speed, shifted into neutral and allowed to decelerate freely. The time rate of change of its velocity is proportional to the total resistive force, which is assumed to consist of a speed-independent rolling resistance and an air resistance proportional to the square of the vehicle&#39;s speed.
A smartphone attached to the model vehicle provides the time-dependent acceleration data, which is usually noisy and needs to be smoothed. The vehicle velocity, on the other hand, can be obtained from the acceleration data by numerical integration. By plotting the vehicle acceleration on the abscissa and the velocity square on the ordinate in a coordinate system for the coasting process, a straight line can be fitted. From the slope of this straight line, the aerodynamic drag coefficient can be derived, and its intersection with the ordinate provides information on the rolling resistance coefficient.
Three teams of three or four students each worked simultaneously and competitively on that project. They independently conducted experiments and developed computer programs for the visualization of the data and evaluation of the measurements. In this paper, the theoretical background, the approach to the problem and the outcome of the undergraduate student projects are presented and discussed.

AU - Günter Bischof
AU - Felix Mayrhofer
AU - Domenic Mönnich
AU - Christian J. Steinmann
CY - Baltimore , Maryland
DA - 2023/06/25
PB - ASEE Conferences
TI - Determination of Road Load Coefficients with Smartphone Accelerometers
UR - https://peer.asee.org/43015
DO - 10.18260/1-2--43015
ER -