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The Impact Detector Project: Mechanical and Electrical Worlds Collide

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2020 ASEE Virtual Annual Conference Content Access


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Publication Date

June 22, 2020

Start Date

June 22, 2020

End Date

June 26, 2021

Conference Session

Instrumentation Division Technical Session 2

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Dale H. Litwhiler Pennsylvania State University, Berks Campus

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Dale H. Litwhiler is an Associate Professor at Penn State, Berks Campus in Reading, PA. He received his B.S. from Penn State University, M.S. from Syracuse University, and Ph.D. from Lehigh University all in electrical engineering. Prior to beginning his academic career, he worked with IBM Federal Systems and Lockheed Martin Commercial Space Systems as a hardware and software design engineer. He is also a registered professional engineer and an instrument-rated private pilot.

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Mechanical engineering students at ______________ University were tasked with designing and fabricating an impact detector to meet a detailed specification. The device was intended to be similar to that used to trigger the inflation of automobile airbags. The project was part of a third-year instrumentation and measurement theory course and was implemented to provide the students with exposure to mechanical and electrical design, fabrication, test, and documentation techniques and methods. Students worked in teams of two or three members. The device specification provided detailed electrical, mechanical, and physical requirements for the impact detector. A major requirement was the range of accelerations that must trigger the device and the range that must not cause the device to trigger. An acceleration greater than 35g for a duration of 1ms or longer must cause the device to trigger. Any duration of acceleration with an amplitude less than 25g must be ignored by the detector. Detector output for acceleration profiles between these two conditions is not defined. The detector output is a voltage pulse (logic high) with a nominal duration of one second when an appropriate impact event occurs. Otherwise, the output of the detector should be zero (logic low). Another important requirement of the detector is that it must fit inside a prescribed enclosure (1.25” x 1.25” x 1.10”). The enclosure is mounted to an impact sled for testing. The sled also contains a reference accelerometer to measure the actual profile of the impact during device testing. The sled is struck horizontally with a spring-loaded rod like that found in a pinball machine to launch the ball into play. The teams must develop a detailed test procedure to document the compliance of their design with the specification. Faculty and staff developed custom test apparatus for the project. Dynamic test data was captured with a USB data acquisition unit and LabVIEW software. This paper describes the lessons learned by the students and faculty during the project. Examples of impact detectors designed by the students are presented. The custom test apparatus and software are also presented and discussed.

Litwhiler, D. H. (2020, June), The Impact Detector Project: Mechanical and Electrical Worlds Collide Paper presented at 2020 ASEE Virtual Annual Conference Content Access, Virtual On line . 10.18260/1-2--35327

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