This paper presents a systematic approach to generate walking primitive databases for anthropomorphic 3D–bipeds allowing step length adaptation, direction changes and stepping over obstacles. The individual walking primitives are derived by optimal control techniques. Zero moment point (ZMP) and friction conditions at the feet ensuring postural stability of the biped, as well as bounds on the j...

In this paper, we extend state of the art Model Predictive Control (MPC) approaches to generate safe bipedal walking on slippery surfaces. In this setting, we formulate walking as a trade off between realizing a desired walking velocity and preserving robust foot-ground contact (slippage and tipover avoidance). Exploiting this formulation inside MPC, we show that safe walking on various terrain...

The postural stability of bipedal robots is investigated in perspective of foot-rotation during locomotion. With foot already rotated, the biped is modeled as an underactuated kinematic structure. The stability of such biped robots is analyzed by introducing the concept of rotational stability. The rotational stability investigates whether a biped would lead to a flat-foot posture or the biped ...

This paper newly considers the ZMP(Zero Moment Point) of a humanoid robot under arm/leg coordination. By considering the infinitesimal displacement and the moment acting on the convex hull of the supporting points, we show that our method for determining the region of ZMP can be applicable to several cases of the arm/leg coordination tasks. We first express two kinds of ZMPs for such coordinati...

In this paper, we solve the gait planning problem by using the Flexible LIP model, which has been shown to be more realistic w.r.t. the LIP for cost-effective or compliant biped robots for gait generation. We extend a stable inversion approach to obtain bounded Center of Mass (CoM) reference trajectories and show several advantages compared to preview control: avoidance of numerical integration...

We developed a novel rapid mobile robot with zero-moment point (ZMP) stabilization. Most mobile robots cannot move quickly due to their high center of mass and narrow ground contact area. The higher center of mass makes it easier for the mobile robot to tip over. To stabilize mobile robots, we designed a multi-degreeof-freedom inverted pendulum to control the ZMP of mobile robots. Using a feed-...

This work studied biped walking with single (one-leg) support and balance control using reinforcement learning. The proposed Q-learning algorithm makes a robot learn to walk without any previous knowledge of dynamics model. This balance control with single support shifts the Zero Moment Point (ZMP) of the robot to a stable region over walking sequences by means of learned gestures. Hence, the p...

A novel method of Zero-Moment-Point (ZMP) compensation is proposed to improve the stability of locomotion of a biped, which is subjected to disturbances. A compensating torque is injected into the ankle-joint of the foot of the robot to improve stability. The value of the compensating torque is computed from the reading of the force sensors located at the four corners of each foot. The effectiv...

Stability of bipedal locomotion is analyzed using a model of a planar biped written in the framework of systems with unilateral constraints. Based on this model, two different stable walking gaits are derived: one which fulfills the widely used criterion of the Zero Moment Point (ZMP) and another one violating this criterion. Both gaits are determined using systematic model-based designs. The m...