Errors up to ±30 mm in determining the COP with piezoelectric force plates have been reported in the literature. To compensate for these errors, correction formulas were proposed, based on measurements with single point loads. In this paper, it will be shown that the errors in the COP depend on the load distribution. Two examples are presented: (1) simulated balance study, and (2) different pressure patterns during walking. Accurate corrections can only be made for forces distributed over a small area. Errors are expected to be overcompensated if there are only a few pressure peaks separated by large distances. These errors can be as large as the statistical errors 5.8±3.7mm after compensation. For certain situations, it is probably better not to use correction formulas. [S0148-0731(00)01005-0]

1.
Kistler, 1993, Multicomponent Measuring Force Plate for Biomechanics Type 9287A (Operating Instructions), Kistler, Switzerland.
2.
Nigg, B. M., and Herzog, W., eds., 1994, Biomechanics of the Musculo-Skeletal System, Wiley, New York.
3.
Bobbert
,
M. F.
, and
Schamhardt
,
H. C.
,
1990
, “
Accuracy of Determining the Point of Force Application With Piezoelectric Force Plates
,”
J. Biomech.
,
23
, pp.
705
710
.
4.
Sommer, R., Kohler, D., and Calame, C., 1997, “Center of Pressure (COP) Enhancement in Piezoelectric Force Plates,” Proc. XVIth I.S.B. Congress, Tokyo, p. 18.
5.
Winter, D. A., 1995, A.B.C. (Anatomy, Biomechanics and Control) of Balance During Standing and Walking, Waterloo Biomechanics, Waterloo.
6.
Schmiedmayer
,
H.-B.
, and
Kastner
,
J.
,
1999
, “
Parameters Influencing the Accuracy of the Point of Force Application Determined With Piezoelectric Force Plates
,”
J. Biomech.
,
32
, pp.
1237
1242
.
7.
Praxmarer, N. L., 1996, “Simulation of the Plantar Pressure Distribution for Insole Design,” Ph.D. thesis, Technische Universita¨t Wien, Vienna, Austria.
8.
McCaw
,
S. T.
, and
DeVita
,
P.
,
1995
, “
Errors in Alignment of Center of Pressure and Foot Coordinates Affect Predicted Lower Extremity Torques
,”
J. Biomech.
,
28
, pp.
985
988
.
9.
Johnson, K. L., 1984, Contact Mechanics, Cambridge University Press, Cambridge.
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