Hb. Schmiedmayer et J. Kastner, Parameters influencing the accuracy of the point of force application determined with piezoelectric force plates, J BIOMECHAN, 32(11), 1999, pp. 1237-1242
Errors up to +/- 30 mm in determining the point of force application with p
iezoelectric force plates have been reported in the literature (Kistler, 19
84. Multicomponent Measuring Force Plate for Biomechanics and Industry. Kis
tler, Switzerland; Bobbert and Schamhardt, 1990. Journal of Biomechanics 23
, 705-710; Sommer et al., 1997. Proceedings of the XVI th I.S.B. Congress).
To explain the main Factors influencing the systematic errors the force pl
ate system is modeled as a two-dimensional beam structure. By this model it
is strongly indicated that the cause for the errors in determining the poi
nt of force application are bending moments in the measurement posts. The m
ain parameters influencing the shape and magnitude of the error function ar
e the ratios between the bending stiffness of the plate and the bending and
compressive stiffnesses of the measurement posts. In the current design it
is therefore not possible to eliminate the cause for the errors by changin
g the constructive parameters. By comparing the error functions derived wit
h the beam model to the correction formulas given in the literature an impr
oved algorithm is proposed. This paper shall help biomechanists in understa
nding the basic concepts of determining the point of force application with
force plates and in constructing custom-made force plates for specific app
lications. (C) 1999 Elsevier Science Ltd. All rights reserved.