A Simplified Musculoskeletal Hip Model for Replicating the Natural Human Walking Behavior

Musculoskeletal models provide an alternative way to explore the function of muscles. The purpose of this study is to develop a simplified musculoskeletal hip model with lumped muscles to investigate the biomechanics and energetics of biological muscle groups during human walking. Our hip model is actuated by four active Hill-type muscle-tendon units (MTUs) and a passive torsional spring representing elastic tissues, the lumped muscle parameters of the model are derived from initial muscles within a group and optimized to make it output human-Iike profile of the joint moment. The coefficient of determination and root mean squared error (RMSE) are both used to validate the hip model. Our results show the coefficient and normalized RMSE related to body weight are both in the statistical acceptance range, which validate the ability of our model replicating human behaviors at the hip joint-level. The calculated muscle activation and total metabolic energy consumption of the hip MTUs also match the experimental data well, which further validate the performance of the model at a deeper muscle-level.