MEASUREMENT OF GROUND SLOPE AND ASPECT USING TWO INCLINOMETERS AND GPS

Abstract

Slope and aspect are two important topographic attributes affecting crop production. In order to quantitativelydescribe the influence of slope and aspect, two electronic inclinometers and a GPS (Global Positioning System) receiverwere installed on two combines and a tractor to measure ground slope and aspect under actual field working conditions. Acomputerized data acquisition system was used to sample angle data and position information. The general case of a vehiclemoving on ground having both direct and cross slopes was examined and algorithms were developed to calculate groundslope and aspect based on the angles measured by the inclinometers and the position data from GPS. Field tests showed thesystem performed well under severe conditions. A comparison between the calculated slope and aspect values and thosederived from a contour map showed that the procedures and algorithms presented in this article were correct and accurate.