Property Classification through Sensing
Capacitive Sensor Setup
Rabbit 2000
MIDN 1/C Nicholas A. Dadds
Advisor: Dr. Svetlana Avramov-Zamurovic
Co-Advisor: Dr. Kenneth A. Knowles
Weapons and Systems Engineering
IC
Cable
Temperature Sensor
Stanton 400.V3
Signal Conditioning Circuit
Stylus
MLX90247
Sensor
Roughness Sensor
Left GND
Left Signal
Aluminum Roughness Profile
5V
47k


V oscope
Material
AD7746
*Converts capacitive reading to digital info for Rabbit*
Capacitive Sensor Leads
PVC Roughness Profile
*Output signal is an analog voltage
C    d  const.
Lead Length
Dielectric constant of Material
Material Type Classification Based on
Capacitance
Material
Mean
Relative
Capacitance Uncertainty
[% Full
[ppm]
Scale]
Air
0.59597
7
Wood
0.59931
7
PVC
0.59705
7
Aluminum
0.5732
50
* In order to avoid contact between the
Aluminum material and the sensor a
sheet of paper was placed in between
the two for isolation*
Signal Conditioning Circuit
Internal Schematics
The dielectric constant in the capacitance equation
above varies depending on the type of material
placed around the sensor. Therefore, each
specific material type will produce a unique
capacitive result. Under stable conditions, when
calibrated for a specific set of materials this sensor
is capable of providing data useful in determining
what material is in the surrounding environment.
The plots shown above were obtained through the use of the Stanton
400.V3 Stylus. These plots show the general surface roughness of a given
material and when viewed in comparison we get an idea of how the two
surfaces relate to each other with respect to their roughness
characteristics. We are able to compare the mean voltage value produced
across a defined length of the material as well as the maximum peak
voltage value, and the frequency of occurrence. Currently the roughness
sensor is only connected so that it can obtain signals when moving to the
left. However, for future work we will connect the right signal as well as
design a device that will standardize the height and displacement of the
sensor for each measurement.
Wood Roughness Profile
Signal Conditioning Circuit
Roughness Sensor
Stylus
Left GND
Left Signal
Stanton 400.V3
5V
47k


V oscope
PVC Roughness Profile
Aluminum Roughness Profile
Wood Roughness Profile