Analysis of human abnormal walking using zero moment joint: required compensatory actions

Area of Science:

• Biomechanics
• Human Gait Analysis
• Robotics

Background:

• Understanding human locomotion is crucial for diagnosing and treating gait abnormalities.
• Diseased joints significantly impact walking patterns, necessitating advanced simulation models.
• Existing models may not fully capture the complex compensatory mechanisms in abnormal walking.

Purpose of the Study:

• To develop and present a multi-body dynamic model capable of simulating both normal and abnormal human walking.
• To investigate the effects of a diseased joint, modeled as a zero moment joint (ZMJ), on gait characteristics.
• To analyze compensatory strategies employed by the body to overcome the loss of joint function.

Main Methods:

• Development of a multi-body dynamic simulation model.
• Introduction of a zero moment joint (ZMJ) to represent a diseased joint, capable of force transmission but not moment generation.
• Simulation of walking with ZMJ at different lower limb joints (hip and knee).

Main Results:

• The model successfully simulated normal and abnormal walking patterns.
• A ZMJ at the hip joint led to pronounced abnormal gait characteristics, hindering realistic walking simulation.
• A ZMJ at the knee joint allowed for more realistic walking simulations compared to the hip ZMJ.

Conclusions:

• The multi-body model provides a valuable tool for studying human gait abnormalities.
• The location of the diseased joint (hip vs. knee) significantly influences the severity and manifestation of abnormal walking.
• The ZMJ concept effectively represents an extreme case of joint dysfunction, highlighting the importance of joint moment generation in locomotion.