Effect of Soil Particle Size on the Accuracy of Tactile Pressure Sensors
Karim Kootahi, Anthony Kwan Leung
Abstract
This paper investigates the effects of soil particle size on the measurement accuracy of single-point type tactile pressure sensors when used for measuring soil contact stresses. Sensors with two different diameters (Dsens) are integrated into an oedometer cell. Granular materials with a wide range of particle diameters (D50) and angularities (from rounded to irregular shaped) are evaluated, resulting in a wide range of ratios of Dsens/D50 from 2.6 to 105.8. The test results show that the soil particle size significantly affects and exponentially correlates with the measurement accuracy of the sensor. A threshold Dsens/D50 of 10.5 is identified for the sensor, beyond which the error is less than 5%. It is also shown that even for ratios of Dsens/D50 as large as 40, an error of approximately 2% can be observed, which is intrinsic to the sensor.