Extended passive velocity field control with variable velocity fields for a kneed biped

In this paper, two aspects for task specification and control of biped walking robot, i.e. (i) realization of safe control against human beings and the outside environment by utilizing a passive velocity field controller (PVFC), and (ii) energy-effective gait design based on virtual passive dynamic walking, are studied and a new control method is derived based on them. In our previous work, we have given a method which satisfied the required properties and examined the validity by numerical simulations. In the method a single trajectory is realized; however, the walking behavior should be modified and adapted by its energy level and initial conditions. Based on the observations, we introduce multi-pattern walking using the virtual passive gait to realize more natural walking motion. The virtual passive gait is shown to require less control input than other methods which can generate a limit cycle automatically without any gait design, and we combine the virtual passive walk with PVFC to change its walking speed easily and effectively.