Prediction of ground reaction forces and moments during various activities of daily living

http://www.bgu.ac.il/~rriemer/papers/Riemer%20at%20el%202008%20Uncertainties%20in%20inverse%20dynamics%20solutions%20A%20comprehensive.pdf

Uncertainties in inverse dynamics solutions: a comprehensive analysis and an application to gait.

A simple method for calibrating force plates and force treadmills using an instrumented pole

This work takes part in the project of development of an anthropomorphic biped robot, Bip. The technological construction has been completed and the robot has performed some slow static walks. The next stage is the implementation of fast and dynamic walking gaits, in other words anthropomorphic gaits. The robot feet have been designed with a three-axes force-moment sensor for reconstructing the center of pressure-zero moment point. To study and test these feet, the idea is simple: the experimental setup consists of a human walker wearing the Bip feet as shoes, a force-plate and a motion analysis system. The purpose is double. The first one is aimed at comparing the contact pressure forces reconstructed with the Bip sensor feet, with the data recorded by the force-plate. The second one consists in determining the influence of (relatively) heavy and rigid metallic shoes on the gait of a human walker. If these feet were proving to be a handicap for efficient and elegant human walking gaits, how could it be any different for the robot Bip? Fortunately the analysis shows that they do not really handicap the walker.

Gait analysis of a human walker wearing robot feet as shoes

Do strain gauge force platforms need in situ correction

Parameters influencing the accuracy of the point of force application determined with piezoelectric force plates

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 +/- 3.7 mm) after compensation. For certain situations, it is probably better not to use correction formulas.

Josef Kastner

Papers

Parameters influencing the accuracy of the point of force application determined with piezoelectric force plates

Enhancements in the accuracy of the center of pressure (COP) determined with piezoelectric force plates are dependent on the load distribution.