Tire Force Estimation in Off-Road Vehicles Using Suspension Strain and Deflection Measurements

Abstract

This thesis develops and analyzes the improvement of tire force estimation and analysis using strain gauge sensors and displacement sensors mounted on the suspension of an all-terrain vehicle. Vehicle dynamic models are developed and validated against simulation data acquired from commercially available CarSIM vehicle simulation software. Improved measurements of the vehicle provide more accurate model parameters used in simulation of the test platform. These improved models are then compared against real data collected from the Prowler All-Terrain Vehicle, a fully instrumented ATV. Suspension force measurement techniques, including strain gauges mounted to the a-arm linkages and deflection potentiometers mounted to the coil-spring assembly were developed and installed onto the testbed. A method for analyzing these force measurements and a methodology to decouple the forces at the tire contact patch into vertical, lateral, and longitudinal components is developed. Results show that this measurement technique is a viable and relatively low-cost method to augment dynamic tire force knowledge in unmanned vehicle systems. Finally, a discussion on the benefits and drawbacks of using this type of sensing method is presented, as well as potential applications of this work.