Running Trajectory Generation Including Gait Transition between Walking Based on the Time-Varying Linear Inverted Pendulum Mode

This paper presents a novel running trajectory generation method for humanoid robots based on the time-varying linear inverted pendulum mode (LIPM). Vertical motion of the CoM, which is crucial for both steady-state running and transitions between walking and running, can be generated by simply optimizing the stiffness parameter of the LIPM during each contact phase. Since our method is a natural extension of walking trajectory generation method based on the conventional LIPM, it is capable of realizing natural and seamless gait transition between walking and running. Moreover, since the proposed method makes use of closed-form solutions of the LIPM, it is more computationally efficient than existing methods based on time-discretization with a fixed time step. Several simulations are performed to evaluate the efficiency of our method.