An Inverse Dynamic Approach for Quantitative Muscle Force Estimation during Human Standing-Up Process

Abstract

As it is inconvenient to directly measure tension forces of muscles attaching on limbs, an inverse dynamic approach for quantitative muscle force estimation during human standing-up process was developed. In the standing-up experiment, a rehabilitation robot was used for offering assistance and measuring dynamic parameters of body segments. Ground reaction force (GRF) and center of pressure (COP) of human body, rotational motions of trunk, thigh and shank were real-time measured by the sensors of the robot system. Meanwhile, the AnyBody Modeling System was adopted for calculating muscle forces of lower limbs. In AnyBody Modeling System, a musculoskeletal model composed of thigh, shank, foot, four joints and fifteen muscles was developed. The GRF, COP and motion data measured with sensors were imported into the model, and then the tension forces of muscles of lower limb were calculated through an inverse dynamics method. Furthermore for the validation of the rehabilitation experiment, the activation levels of muscles were also directly measured by an electromyography (EMG) system, and the calculated AnyBody results matched the measured EMG results. Therefore, this muscle force estimation approach appears to be practical for determining muscle forces in the musculoskeletal analysis of human limbs.