Disclosed are several examples of a ground reaction force sensor for an article having an upper force plate for contacting the article, a lower force plate for contacting the ground, a vertical load cell disposed between the plates for measuring the force acting on the cell in a direction that is substantially perpendicular to the surface, a horizontal load cell disposed between the plates for measuring the force acting on the cell in a direction that is substantially parallel to the surface, and with the load cells being mounted between the plates in a configuration that is substantially insensitive to off-axis forces imposed on them for improved load cell measurement accuracies. Various other features and benefits are provided.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT.
 This invention was made with government support under Contract No. DE-AC05-000822725 awarded by the U.S. Department of Energy. The government has certain rights in the invention.