Effects of foot modelling on the human ankle kinematics and dynamics

• Effects of foot modelling assumptions on ankle kinematics and dynamics were studied.
• An interpolated function capable of predicting ankle flexion axis was proposed.
• Number of segments of the foot model does not have effects on the ankle joint torque.
• Ankle power can be affected by the foot segmentation and dimension of the foot model.

In this study, effects of some of the foot modelling assumptions on the ankle kinematics and dynamics are investigated based on the experimental data. For the kinematics analysis, the appropriateness of the stationary axis of rotation of the human ankle flexion is examined. Moreover, an interpolated function which is capable of predicting the directional changes of this axis is proposed. For the dynamics analysis, two main modelling assumptions of the number of the foot segments and the dimension of the foot model are the subject of the study. To this end, the ankle joint torque and power are selected as the comparison indicators and inverse dynamics analyses are carried out. The analyses show that the number of segments of the foot model does not have a considerable effect on the calculated ankle joint torque. On the other hand, the calculated ankle power is highly affected by both of the segmentation and the dimension of the foot model.