Dynamical analyses of humanoid's walking by visual lifting stabilization based on event-driven state transition

Abstract

Biped locomotion created by a controller based on Zero-Moment Point [ZMP] known as reliable control method looks different from human's walking on the view point that ZMP-based walking does not include falling state. However, the walking control that does not depend on ZMP is vulnerable to turnover. Therefore, keeping the event-driven walking of dynamical motion stable is important issue for realization of human-like natural walking. In this paper, walking model of humanoid including slipping, bumping, surface-contacting and point-contacting of foot is discussed, and its dynamical equation is derived by Newton-Euler method. Then, we propose walking stabilizer named "Visual Lifting Stabilization" strategy to enhance standing robustness and prevent the robot from falling down. Simulation results indicate that this strategy helps stabilize pose and bipedal walking even though ZMP is not kept inside convex hull of supporting area.

Walking analyses of a humanoid by visual-lifting approach

“…A condition that heel of supporting-foot detaches from the ground in Fig. 4 (I), (III), (III'), (V), to (II), (IV), (IV'), (VI) was discussed in [26].…”

“…In these gaits, contacting patterns make the dimension of state variables change and they change constraint conditions VIce versa. Detail explanation is described in [26]. …”

Dynamic Reconfiguration Manipulability analyses of humanoid bipedal walking

“…Our model represents rigid whole body-feet including toe, torso, arms and bodyhaving 18 degree-of-freedom. Detail explanation of this model is omitted, which is described in [9].…”

A first step of humanoid's walking by two degree-of-freedom generalized predictive control combined with Visual Lifting Stabilization

“…5 is Jacobian matrix of the head pose against joint angles including q 1 , q 2 , q 3 , q 4 , q 9 , q 10 , q 11 , q 18 , and K p means proportional gain similar to impedance control. We use this input to compensate the falling motions caused by gravity or dangerous slipping motion happened unpredictably during walking states [21]. Notice that the input torque for non-holonomic joint like joint-1 (toe of supporting-foot), τ h1 in τ h (t) in Eq.…”