Development and evaluation of new simple mechanisms for shock absorption of the ankle

Abstract

Diverse types of high-precision body modeling have been proposed to improve the efficiency of rehabilitation work and exercise in sports and other activities. In this study, a simple below-knee model of the body was created. First, the moment of inertia around the ankle was calculated, and the center of gravity position on the sole of the foot, which is decided by the body inclination, the ball of the thumb, and the reaction force on the heel, was used as the basic model. Based on this basic model, the force acting on the center of gravity of the body was calculated as a first-order lagging element, and it was found that in order to reduce the ankle torque, it is not necessary to increase the proportional gain of the force output per body displacement (how much force can be produced), but to reduce the time constant T In order to reduce the ankle torque, it was observed that making the time constant T small (how fast the force can be generated) is a major factor. When the spring-damper system was added to the model as well as the force generation mechanism, it was found that increasing the damper coefficient was also effective in reducing the ankle torque. Increasing the damper coefficient means how quickly a large force can be generated when an impact is applied. In other words, to reduce the burden on the ankle, it is effective to have a flexible body with the agility to produce quick and large forces.

Keywords

• Knee
• Ankle
• Ankle torque
• Mathematical model
• Body factors