In-situ verification of accuracy, precision and resolution of force and balance platforms

It is common practice in laboratories to check for accuracy, precision and resolution of instrumentation before using it inresearch. For force platforms used in gait analysis and balance measures, most of these verifications are done in staticconditions, i.e., applying known weights in known locations on the surface of the instrument, measuring what the output is,and comparing it with what it should be. However, this is not a realistic simulation of a subject standing on the instrument,as the Center of Pressure (CoP) varies continuously over time and covers a good portion of the area of support. Otherauthors have proposed a device to assess how well a force platform measures a time-changing CoP trace by comparing themathematically known, spiral-shaped trace generated by a rotating mass with what is measured by the force platform.Changing mass and rotation speed allows evaluation of a wide range of frequencies and areas of support. In this paper, thedifferent in-situ verification techniques most commonly mentioned in the literature were investigated from a theoreticalpoint of view and then compared using commercially available balance platforms, to assess their ability to verify accuracyand resolution of force platforms.