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Capacitive Sensing Accelerometer
  • Max Miller,
  • Tristan Anderson
Max Miller
University of New Hampshire
Author Profile
Tristan Anderson
University of New Hampshire

Abstract

For our final project in PHYS605, Tristan Anderson and I have built an electro-mechanical accelerometer utilizing technics outlined in at PDF released by Maxim Integrated \cite{dadafshar2014}. The approach utilizes capacitance sensing and kinematics to translate arbitrary changes in the devices' sensed capacitance to the acceleration the device is experiencing at a given time. Our device is a one-dimensional accelerometer which utilizes two capacitance sensors, an Arduino  Duemilanove, a known mass charged plate in an oscillating system made using non-conductive foam, and housing made of PVC. The creation is broken into two stages, with the first being the initial testing and prototyping of the circuit, code, and mechanical systems outline and the second being the creation of a prototype electro-mechanical, large-scale accelerometer implementing machined parts and materials. All code utilized can be found in the Code section \ref{512015}. The primary package utilized for the capacitance sensing is CapacitiveSensor \cite{capacitivesensor} , a standard library which allows for the measuring of charge-time between two GPIO pins on the Arduino. Any additional code was written by myself, including a web server written in Go which allows for us to actively monitor and log the accelerometers behavior. The source code is in the Code section under \ref{843961}, as well as in the listed GitHub repository. The largest assumtion we took in the creation and testing of this device was that the foam provided behaved inline with Hooke's Law, having oscillations in the form:
 \(F\ =\ -kx\)
This assumtion is needed to fomulate our equation for acceleration of the known mass.