Calculation of a force effect from muscle action to a quaternion-based musculoskeletal model

TL;DR

This paper develops a mathematical framework for modeling muscle forces in quaternion-based musculoskeletal simulations, overcoming limitations of Euler angles like gimbal lock, and demonstrates its application on a 3D double-pendulum system.

Contribution

It introduces a novel method for estimating muscle torques in quaternion-based models and transforms muscle moment arms from Euler angles to quaternions, enhancing dynamic modeling capabilities.

Findings

Effective quaternion-based muscle torque estimation demonstrated on a double-pendulum system.

Transformation of muscle moment arms from Euler angles to quaternions shown to be feasible.

Method advantageous for complex joint kinematics like the shoulder.

Abstract

Euler angle representation in biomechanical analysis allows straightforward description of joints rotations. However, application of Euler angles could be limited due to singularity called gimbal lock. Quaternions offer an alternative way to describe rotations but they have been mostly avoided in biomechanics as they are complex and not inherently intuitive, specifically in dynamic models actuated by muscles. This study introduces a mathematical framework for describing muscle actions in dynamic quaternion-based musculoskeletal simulations. The proposed method estimates muscle torques in quaternion-based musculoskeletal model. Its application is shown on three-dimensional double-pendulum system actuated by muscle elements. Furthermore, transformation of muscle moment arms obtained from muscle paths based on Euler angles into quaternions description is presented. The proposed method is advantageous for dynamic modeling of musculoskeletal models with complex kinematics and large range of motion like the shoulder joint.