Abstract-Principal mechanisms of passive dynamic walking are studied from the mechanical energy point of view, and novel gait generation and control methods based on passive dynamic walking are proposed. First, a unified property of passive dynamic walking is derived, which shows that the walking system's mechanical energy increases proportionally with respect to the position of the system's center of mass. This yields an interesting indeterminate equation that determines the relation between the system's control torques and its center of mass. By solving this indeterminate equation for the control torque, active dynamic walking on a level can then be realized. In addition, the applications to the robust energy referenced control are discussed. The effectiveness and control performances of the proposed methods have been investigated through numerical simulations.
This paper proposes a novel energy-based control law for biped robots based on an analysis of passive dynamic walking. Firstly we discuss the essence of dynamic walking wing a passive walker on a gentle slope. In the second, we propose a simple and effective control law which imitates the energy behavior in evev cycle considering the ZMP condition and other factors of the active walker. The control strategy is formed by the feature of mechanical energy dissipation and restoration. By the eflect of the proposed method, the robot can exhibit natural and reasonable walk on a level ground without any gait design in advance. The validity of the proposed method is examined by numerical simulations and experiments.
Restoration of mechanical energy dissipating on impact at the ground is necessary for sustainable gait generation. Parametric excitation is one approach to restore the mechanical energy. Asano et al. ("Parametric excitation mechanisms for dynamic bipedal walking," IEEE International Conference on Robotics and Automation (2005) pp. 611-617.) applied parametric excitation to a biped robot with telescopic-legs, in which up-and-down motion restores total mechanical energy like playing on the swing. In this paper, parametric excitation principle is applied to a kneed biped robot with only knee actuation and it is shown that the robot walks successively without hip actuation. We also examine influences of several parameters and reference trajectory on walking performance.
It has been shown that a simplest walker with suitable parameter choice can walk down a gentle slope without any control forces and generate its steady walking pattern utilizing gravity effect automatically. O n the floor, however, the robot cannot exhibit passive walk, so any application methods of passive walk to active walker o n the horizontal floor has not been studied yet. Based o n the observation, in this paper we introduce "virtual passive dynamic walking" with virtual gravity field which acts as a driving force f o r the biped robot. The robot can walk on the floor without any control torque except virtual gravity effect. Since the modified gravity field seems t o be very close to real condition, the generated walking pattern seems to be natural. Further, multi-pattern walking w.r.t. energy level is proposed. With the proposed above method, safety and energy-effective control of biped walking robot can be realized.
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