Abstract :
Passive-dynamic-walking (PDW) had been noticeable in the research of biped walking robots. In this paper, using the concept of delayed feedback control (DFC), we provide control methods of quasi-passive-dynamic-walking, in which the actuators are used just only when the walking begins or disturbances come in. Concretely, at first, focusing on the contact phase of the swing leg with the ground, we propose "discrete-DFC based control method" which is very simple and do not require any reference trajectory. Secondly, expanding the above control method, we propose, "updating reference trajectory control method based on DFC", which uses (k-1)-th step\´s trajectory of the walking robot as k-th reference trajectory.