Effect of applied-force misalignments on rolling resistance measurements using the force method

This study investigated the influence of force-application misalignments on measurements of rolling resistance in wheels using the force method. A theoretical model was developed to predict measurement errors caused by angular deviations between the load-cell axis and the normal direction of the rolling surface, as well as by horizontal axle offset during measurements on a cylindrical surface. The model was experimentally evaluated by measuring the rolling resistance coefficient of roller-ski wheels on both a flat treadmill rolling surface and a cylindrical rolling surface. The results demonstrated that force-based rolling-resistance measurements are sensitive to small geometric misalignments. Angular deviations affected measurements on both flat and cylindrical rolling surfaces, whereas horizontal axle offset affected measurements on the cylindrical rolling surface. The experimentally measured rolling-resistance coefficients showed good agreement with the corresponding values predicted by the theoretical model across all tested conditions. This indicates that the model adequately captures the dominant effects of applied-force misalignment on measurement errors. The findings highlight the importance of accurate force-transducer alignment and wheel positioning in rolling-resistance measurements when using the force method. Overall, the proposed theoretical model provides a practical tool for predicting and correcting alignment-induced measurement errors in laboratory-based rolling-resistance testing.