TORQUE ANALYSIS OF LOWER LIMB BASED ON UDWADIA–KALABA APPROACH AND INERTIAL SENSOR MOTION DETECTION

Abstract

This paper presents an explicit dynamic equation of motion of human unilateral lower limb based on Udwadia–Kalaba approach and conducts experiments to verify the practicability of the novel approach. A three-segment, planar model with two-degrees-of-freedom is derived to represent the lower limb when the hip and knee do the extension-flexion motion as the human body lies flat. We reframe the joint torque analysis of lower limb as a problem of constrained motion in analytical dynamics, in which the joint torque supplied by a human body is treated as constraint torque and the motion as the constraint. A Wearable Human Posture Detection System (WHPDS) based on MEMS inertial sensors is designed. The original angle curves of hip and knee joints are explicitly obtained by WHPDS and used to calculate the joint constraint torques. No auxiliary variables such as Lagrangian multipliers or pseudo-generalized speeds are used in the dynamic modeling or analysis. Analysis of human unilateral lower limb can be helpful in many fields such as rehabilitation therapy. It is beneficial for assessing effectiveness in rehabilitation therapy and selecting appropriate rehabilitation strategies.