Study on Human Ankle Joint Biomechanical Dynamics During Upright Standing ‘Sandbag-Disturbance’ Push-Recovery

摘要

The ankle joint biomechanical dynamics plays an important role in the balance of the human body, especially under the small disturbance. In this paper, ankle joint biomechanical dynamics and muscle reflex control are investigated. Soleus(SOL), gastrocnemius(GAS) and tibialis anterior(TA) are selected to record the surface electromyography for analysis. Ankle joint angle is recorded by an encoder. The pressure insole records the foot pressure and the ankle joint torque is calculated using the data. The disturbance is exerted by a sandbag released at different height to hit backs of subjects. The experimental condition is controlled so that subjects pay no attention to the disturbance for upright standing balance. Seven subjects participate in the experiment. The experimental results indicate that there is no significant differences among muscle activation levels for different level disturbances. The linearity between the SOL activation and ankle joint torque is high. The joint angle and the torque also have high linearity. Considering that muscle reflex has the function of regulating muscle stiffness, the ankle joint seems to maintain ‘stiffness’ within a small variation to resist limited range external disturbance.