Human leg adjustment in perturbed hopping

Robots can help to demonstrate and prove concepts on human locomotion such as concepts based on springlike leg behavior. Hopping is a fundamental requirement for run-ning in two basic functions: bouncing and balancing. In addition, for robust hopping against perturbations, swing-ing the leg in flight/swing phase is observed. These three elements need to be integrated for stable/robust locomotion in bipeds. Unlike running [1] and walking [2], stable hop-ping cannot be achieved with a fixed angle of attack with respect to the ground. So, finding an appropriate leg direc-tion during the flight phase is needed for stable hopping in place. In this study, different methods of leg adjustment dur-ing swing phase are compared both in simulation with SLIP (Spring Loaded Inverted Pendulum) model and in human experiment. Because of the lack of space and since we re-ported the simulation results previously [3], in this paper, it is just reported with a few sentences. Our presented method called VBLA (Velocity Based Leg Adjustment) shows better performance in modeling and is also closer to what humans do.