An experimental study for analyzing static stability using two load cell methods

Abstract

This paper reports on the design, fabrication, and performance evaluation of a two load cell based force plate that can measure static stability. The force plate was manufactured using conventional machine tools for substantially lower cost than commercially available units. To achieve these attributes, the force plate embodied two octagonal load cells that were instrumented with conventiona1 strain gauges. The mechanical design of load cell was tested in ANSYS 10.0 and the mounting of strain gauge on the octagonal ring made as per ANSYS result Strain gauge signals were amplified by simple signal conditioning circuits with a low component count. The four strain gauge output after amplification and filtered, interfacing to personal computer through data acquisition LAB JACK card. The factors of stability evaluated were: sway velocity, AP range, R.M.S. distance, Mean Distance, Sway Area, Mean power frequency, the dependence on vision as indicated by ratio of eye open and eye close values. The simulation results in ANSYS showed that the maximum deflection in a load cell was less than 0.154 mm when a load of 1000 N applied vertically. The preliminary clinical results tested with normal subjects demonstrated that the two load cell force plate provides similar output in comparison to conventional force plate.