Establishment and verification of a mechanical model for analyzing the forces acted on lower limb during walking

To analyze the stress state of lower limb accurately and simply during walking, a novel mechanical model of human lower limb is proposed. The upper body is treated as a lumped weight; the thigh, calf and foot are considered as three rigid rods; the ankle, knee and hip are simplified as the link joints between the lumped weight and rods; and the muscle forces are simplified as four unknown forces acting on the rods. Based on this model, the corresponding dynamics equations are derived to describe the movement of feet and legs. Using the kinematic and dynamic data collected by high-speed photography and plantar strainmeter, these equations are solved, and the stress state of lower limb is obtained. Moreover, the limb muscle potentials are measured by surface electromyography to verify the reliability of the present model. The results show that this model can reflect the stress state of knee and ankle with high biological fidelity, and provide guidelines to study the mechanism of human lower limb movement and develop lower limb sports equipment.