Influence of human induced floor vibrations on the measurement precision of force plates in a biomechanics laboratory

In gait analysis laboratories the ground reaction force time histories of the footfall of persons are usually measured using a force plate. The accelerations of the floor, in which the force plate is embedded, have to be limited, as they may influence the accuracy of the force measurements. For the numerical simulation of vibrations induced by humans in gait analysis laboratories, loading scenarios are defined. They include continuous motions of persons (walking, running) as well as jumps, typical for biomechanical investigations on athletes. Criteria for the assessment of the measuring error provoked by floor vibrations are given. As example a floor designed to accommodate a force platform in a biomechanical laboratory of the University Hospital in Tubingen, Germany, has been investigated for footfall induced vibrations. The numerical simulation by a finite element analysis has been validated by field measurements. As a result, the measuring error of the force plate installed in the laboratory is obtained for diverse scenarios.