title: Evaluation of a force plate system for measuring center of pressure in railroad ballast.
abstract: Traditional biomechanical analyses have focused primarily on the human gait across hard, flat surfaces and provide little information about human locomotion as a function of work environment or terrain. The purpose of this study was evaluation of a force plate system for measure of center of pressure (COP) in railroad ballast by comparing its accuracy across three surface conditions (hard surface, mainline ballast and walking ballast) with two configurations (level and 7° cross-slope). Custom walkways and an isolation fixture were developed to rigidly attach a force plate beneath ballast surfaces to collect the COP. The difference in COP location (ΔCOPx, y, z) between the force plate system and a calibration system (motion capture derived) were compared using repeated-measures analysis of variance. Results indicate that the effects of surface condition and configuration were not significant for ΔCOPx, y, z and no differences were found among the three surface conditions during pairwise comparison, though ΔCOPx, y, z were different between the center and corners of the force plate in ballasts for both level and cross-slope configurations. The system presented in this study demonstrates the feasibility of measuring the COP by using an isolation-fixture force plate to expand the scope of biomechanical studies on ballast surfaces that are level or cross-slope.
authors.affiliation: School of Medical Imaging, Xuzhou Medical College, Xuzhou, PR China; Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
authors.forename: Hang
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA. Electronic address: a.merryweather@utah.edu.
authors.forename: Andrew
authors.initials: A
authors.lastname: Merryweather
authors.affiliation: Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Bloswick
mesh_terms: D001696:Biomechanical Phenomena; D002138:Calibration; D004867:Equipment Design / Q000379:methods*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008124:Locomotion; D011312:Pressure; D011890:Railroads / Q000379:methods*; D013499:Surface Properties; D016138:Walking / Q000502:physiology*
keywords: Center of pressure; Force plate; Instrumentation validity; Railroad ballast