Estimation of ground reaction forces for a biomechanical model of human motion

This study aims to build a biomechanical model of the human body's lower extremity and to estimate ground reaction forces by utilising this model. For this purpose, the linked-segment rigid body model of the lower extremity (BMMS) was built in MATLAB/Simulink. The contact forces between the model's feet and ground were modelled using Simscape/Multibody libraries. In the experimental part of the study, a participant's squat, walking and free-fall landing movements were recorded using the VICON optical motion capture system. The kinematic variables were calculated using the Nexus CGM2 model, and a Kistler force plate was used to measure the ground reaction forces during the motions. The ground-contact parameters of BMMS were optimised for the inverse dynamics simulation of the motions. The estimated frictional (FFE) and ground reaction forces (GRFE) were compared to the frictional (FFM) and ground reaction forces (GRFM) measured and recorded via the force plate. In the last stage of the study, the lower extremity musculoskeletal system (BMOS) was built in the OpenSim simulation environment following the same modelling principles as BMMS. The joint torques obtained via the inverse dynamics simulations performed in both MATLAB and OpenSim were calculated for the walking motion of the participant. The study's findings showed that BMMS is consistently accurate in estimating GRFM with less than 6% error and strong linear correlation but incapable of estimating the FFM. The trend in joint torque behaviours, calculated via simulations of BMMS and BMOS, showed similarity but not parallel in magnitude. BMMS is considered a helpful tool in the dynamic simulation of human movement when sufficient development is made in its biomechanical properties and ground-contact model.