Precision Analysis and Recommended Test Procedures for Mobility Measurements Made with an Instrumented Vehicle

This report addresses the precision of mobility measurements made using an instrumented vehicle. Systematic errors were documented and new techniques established to eliminate or minimize these errors. An increase in the precision and accuracy of mobility measurements will allow the successful pursuit of new research efforts of concern to cold regions mobility, such as the resistance measurements of trailing tires and terrain resistance on shallow snow or winter soils. Systematic errors due to calibration methods, temperature, vehicle speed and weight distribution were observed and quantified. Based on these results, suggested techniques to eliminate or minimize these errors and improve precision are as follows. 1 The method of calibration air, static or rolling should be chosen based on the objective of the experiment. Calibrating the vehicle while it is rolling yields the most consistent results from test to test however, a static calibration is needed to measure the total resistance of the vehicle running gear. 2 Because of the wide range of temperatures considered in cold regions testing and the temperature sensitivity of the equipment, the vehicle and all equipment should be operating and temperatures stabilized before vehicle calibration and testing begins. If the weather changes significantly during the course of the tests, it should be noted and the vehicle should be recalibrated.