Using motion analysis data for foot-floor contact detection

A simple, fast and straightforward method was developed for automatically deriving foot-floor contact information from tracking motion analysis system markers attached to the shoes of the subjects. The method was based on an accurate calibration of the motion analysis system prior to the experiments and a trivial off-line threshold-based algorithm using dedicated foot-attached marker positions and velocities as inputs. The main purpose of the method was to obtain the results almost instantaneously. The accuracy was poorer when compared with the classic, man-assisted and time-consuming methods, but the average error was less than 0.1 s compared with the force plate or pressure insole/foot switch-based methods. The method eliminates the need for foot switches when a motion analysis system is already being used. As encumbrance is reduced for the subjects, the method is also applicable to pathological gait patterns.