Instrumentation for Tractor Pitch and Roll Angle Measurement

Abstract

Angular displacement sensors were installed on an instrumented lawn and garden tractor to sense vehicle pitch and roll angle. Two small inclinometers were mounted at right angles to each other onto the tractor frame. The sensors were located above the rear axle. Rather than mechanical movement, the sensor detected the distribution of a dielectric liquid and inert gas pressed between two etched copper-plated discs. Capacitance variations, caused by the gravity-induced repositioning of the mixture, indicated angular displacement. A simple circuit for computer interfacing of the sensor was developed. Roll and pitch angle performance data were collected at differing speeds over a surveyed calibration course. The inexpensive inclinometers were slightly influenced by vehicle acceleration and deceleration, yet acceptable results were obtained for a desired application.