Development of an instrumented blade system for mapping soil mechanical resistance represented as a second-order polynomial

An instrumented blade system for mapping soil mechanical resistance on-the-go was developed. The system consists of a cutting edge that transfers the load from cutting through soil media to a vertical shank equipped with an array of strain gage bridges. The resulting force is transferred between the cutting edge and the blade at three distinct locations and the soil mechanical resistance profile is modeled as a second-order polynomial. The geometry of the blade was determined using an optimization procedure minimizing the total error associated with potential strain gage noise. The instrument was built and calibrated using a set of known point loads. It was found that signal adjustment was needed in order to account for the mechanical transfer of force through the cutting edge. This adjustment was applied using a set of coefficients found through a multiple linear regression. Coefficients of determination, R-2, for regressions between adjusted and theoretical second-order profiles were greater than 0.99. Results of field evaluation and discussion on the potential applicability of the system developed will be presented in a follow-up publication. (C) 2006 Elsevier B.V.. All rights reserved.