A 3D Template Model for Healthy and Impaired Walking

Several modeling studies, which address neuromuscular control in impaired unperturbed gaits, were performed to predict human strategies to cope with lateral asymmetries in the body. Experimental studies show different step length and stance time relations between limbs in walking of stroke patients. By extension of a bipedal SLIP (spring-loaded inverted pendulum) based model and the corresponding controllers to 3D space, we focus on different features of the pathologic gaits. The introduced model is based on an extension of the FMCH (force modulated compliant hip) and VBLA (velocity based leg adjustment) model to 3D space. With the proposed model, asymmetric leg and control parameters can result in similar gait patterns as observed in experiments. These parameters comprise hip stiffness and rest angles in FMCH models and the tuning parameter of VBLA for foot placement. It is shown that asymmetries in muscle properties (e.g. stiffness) and leg adjustment can play an important role in generating pathologic gaits.