Showing papers by "Shuuji Kajita published in 2008"

A pattern generator of humanoid robots walking on a rough terrain using a handrail

Abstract: This paper presents a biped humanoid robot that is able to walk on a rough terrain while touching a handrail. The contact wrench sum (CWS for short) is used as the criterion to judge if the contact between the robot and the environment is strongly stable under the sufficient friction assumption, where the contact points are not coplanar and the normal vectors at the points are not identical. It is confirmed that the proposed pattern generator can make the robot walk as desired in dynamics simulations and experiments, and the motions can be improved by a hand position control and using waist joints.

A friction based “twirl” for biped robots

Abstract: This paper presents preliminary results on generating turning motion of a humanoid robot by slipping the feet on the ground. We start by presenting the fact that such slip motion is used by humans based on actual human motion capture data, and show how this is necessary for sophisticated human-like motion. To generate the slip motion, we predict the amount of slip using the hypothesis that the turning motion is caused by the effect of minimizing the power generated by floor friction. Verification is conducted through both simulation and experiment with the humanoid robot HRP-2. A ldquotwirlrdquo utilizing both feet slip is successfully demonstrated.

Kinodynamic gait planning for full-body humanoid robots

Abstract: This paper proposes the kinodynamic gait planning for humanoid robots where both kinematics and dynamics of the system are considered. We can simultaneously plan both the foot-place and the whole-body motion taking the dynamical balance of the robot into consideration. As a dynamic constraint, we consider the differential equation of the robotpsilas CoG. To solve this constraint, we assume two walking pattern generators; the offline and the online ones. We randomly sample the configuration space to search for the path connecting the start and the goal configurations. When sampling the configuration space, three milestones are sequentially connected to the parent milestone. To show the effectiveness of the proposed methods, we show simulation and experimental results where the humanoid robot HRP-2 walks on several environments.

Motion Generation of Emergency Stop at Double Support Phase for Humanoid Robot by Pole Assignment

Abstract: A motion planner of emergency stop must make an operating humanoid robot to a stationary state from the emergency signal. It plays an important role in prevention of falling over because humanoid robots fall over easily. Immediately after the emergency signal, the emergency stop motion must be generated in real-time. We model a humanoid robot as a simple dynamic system consists of the ZMP (Zero-Moment Point) and the COG (Center of Gravity) as its states. The emergency stop motion is generated by a state feedback. We determine optimal feedback gains in terms of the initial conditions and the pole assignment. The proposed method realizes a reliable emergency stop with low computational cost. Furthermore, it can easily predict the possibility of the successful emergency stop at any time. The validity of the proposed method is confirmed by some experiments using humanoid robot HRP-2.