Statistical analysis of force distribution on the plantar foot during quiet stance

Alkan, Okan
In most of the posture studies, foot is considered as a single rigid body.However, recent works focused on multi-segmented kinematic foot models and ground reaction force distribution beneath the feet. This thesis presents a study on the role of the foot as a deformable body for controlling the human erect posture. A pressure-pad and a force platform were used in order to determine the distribution of ground reaction forces (GRF). Pressure distribution data beneath the feet of seven male and female right-handed subjects were analyzed. 180-second long quiet stance data was collected from the subjects during the eyes-closed and eyes-open conditions in three repetitions. Measurements from the data were computed in both time and frequency domains. The surface of the foot projected to the horizontal plane has been divided into three regions; heel region (talus and calcaneus bone included), medial longitudinal arc region (the navicular, the cuboid and three cuneiforms), and five metatarsal bones and phalanges region, respectively named as hind, mid, and front regions. In time domain, mean and the variance measurements were taken for the pressure distribution at each section of the both feet and cross correlation values of each possible combination of the three-foot regions. In frequency domain, auto and cross power spectral density estimations and coherence function between normal force distribution signals at each possible paired combination of the three-foot regions were computed. We have found that mutual interactions in between the predefined foot regions were different. Furthermore, we observed a particular load shifting behavior in time, especially between hind and modified front foot regions, which showed substantial differences with respect to gender and left versus right foot. A mathematical model for human erect posture has been developed where a deformable foot is used in order to drive and control the human inertial body mass. The parameters of the model were estimated by analyzing the experimental data.
Citation Formats
O. Alkan, “Statistical analysis of force distribution on the plantar foot during quiet stance,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.