Passive stabilization of the trunk in walking

Abstract

In bipedal walking the trunk stabilization is an important control task, as the trunk can be described as an unstable inverted pen- dulum connected on a moving hip. A strategy to stabilize the trunk is to apply a hip torque such that the trunk is transferred to a virtual hang- ing pendulum. This concept generates hip torques, which could partially be exerted by elastic structures. In this simulation study, we test if hip springs could facilitate trunk stabilization. With moderate hip spring stiness and a short free motion around midstance, the springs reveal best robustness. The reductionist model formulation allows to reveal the function of mono-articular muscles surrounding the hip.