Stable running by leg force-modulated hip stiffness

Balancing the upper body as one of the main features in human locomotion is achieved by actuation of the compliant hip joints. Using leg force feedback to adjust the hip spring is presented as a new postural control technique. This method results in stable and robust running with the conceptual SLIP model which is extended by addition of a rigid trunk for upper body. Besides providing stability, this approach can represent the virtual pendulum (VP) concept which was observed in human/animal locomotion. Even more, the duality of this controller with virtual pendulum posture controller (VPPC) was mathematically shown. Such a mechanism could be also interpreted as a template for neuromuscular model.