Analysis of motion of body center during human stair gait using force plate

This paper reports the kinematic characteristics of the mass center of the entire human body while ascending and descending stairs, using large force plates which can measure both three-dimensional force components between the feet and the stair and the point of application of the force, Kinematic characteristics in terms of the velocity and the displacement of the body center in the three-dimensional space can be obtained by numerical integration of the force components with respect to time after proper calibration of measured data. For the calibrations, two methods were use: the first one compensates the measured force according to the sensitivity of the force plates due to their size were large; the second one tunes integration constants to avoid drifting features in integrated data. The following results are obtained: our new method, i.e., obtaining kinematic characteristics for stair gait using force plates, gives reliable results in the three orthogonal directions in space; characteristics in the sagittal and the vertical directions change depending on gait cadence; characteristics in the lateral direction are similar to those observed in level walking.