2026-09-19T11:37:00Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/926842022-01-13T07:54:05Zcom_1721.1_7582com_1721.1_7581col_1721.1_131024
Warren P. Seering.
Whittemore, Samuel Tileston
Massachusetts Institute of Technology. Department of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
2015-01-05T20:05:37Z
2015-01-05T20:05:37Z
2014
2014
http://hdl.handle.net/1721.1/92684
898211484
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 42).
Snow penetrometers create a specific application for a force sensor with specifications that are over achieved at great cost when using traditional load cells. A moderately priced, compact force sensor suitable for this application does not exist, and numerous force-sensing technologies were investigated, from spring and displacement transducer combinations, to strain gauges mounted on plastics, to pressure transducers. The high dynamic range, linearity, and electrical simplicity of low-cost piezo-resistive pressure sensors lent well to rapidly developing a working design on a small budget. Preliminary prototypes show promising results where the natural frequency requirement is 60% above the target specification at wn = 10497 rad/s +/- 92 rad/s. The sensor is nearly ideally damped with damping ratio, [zeta] = .43 +/- .04. A linear model results in acceptable hysteretic error for mid and upper range force values, but the sensor performs inaccurately below 2.8 N (greater than 20% error). While the sensor's performance isn't perfect for all criteria, snowpack simulation tests suggest that the sensor's shortcomings are acceptable for the targeted application of measuring relative snow hardness.
by Samuel Tileston Whittemore.
S.B.
42 pages
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Mechanical Engineering.
Development and testing of an application specific force sensor for snowpack assessment
Thesis
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<Abstract>Snow penetrometers create a specific application for a force sensor with specifications that are over achieved at great cost when using traditional load cells. A moderately priced, compact force sensor suitable for this application does not exist, and numerous force-sensing technologies were investigated, from spring and displacement transducer combinations, to strain gauges mounted on plastics, to pressure transducers. The high dynamic range, linearity, and electrical simplicity of low-cost piezo-resistive pressure sensors lent well to rapidly developing a working design on a small budget. Preliminary prototypes show promising results where the natural frequency requirement is 60% above the target specification at wn = 10497 rad/s +/- 92 rad/s. The sensor is nearly ideally damped with damping ratio, [zeta] = .43 +/- .04. A linear model results in acceptable hysteretic error for mid and upper range force values, but the sensor performs inaccurately below 2.8 N (greater than 20% error). While the sensor's performance isn't perfect for all criteria, snowpack simulation tests suggest that the sensor's shortcomings are acceptable for the targeted application of measuring relative snow hardness.</Abstract>
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