Uncertainty evaluation of a method for the functional reach test evaluation by means of monte-carlo simulation

The Functional Reach Test (FRT) is a simple, portable, clinically accepted tool that is used to measure semi-static balance. In a recent study, video recordings and software elaborationshave beenperformed by a computerized system to determinethe FRT objectively (computerized FRT, cFRT):here an in-depthstudy on the measuring error of the above system is proposed.Main uncertainty sources identifiedare (a) geometrical errorsdue to the alignment of the camera calibration plane with the real motion plane, (b) the difference in depth between the above planes, (c) the image aberration due to the lens that compress the pixels and (d) the software error in position estimation using a template matching algorithm. The uncertainty evaluation is performed by means Monte CarloSimulationsand results suggest that both the depth error and the barrel distortion are the more relevant source of error, althoughthe aberration can be corrected by one of the many algorithms available in literature. Results can be useful to define a measurement protocol to improve the performances of thesystem for a better clinical effectiveness.