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Robots must have similar mechanical impedance characteristics to humans in order to make safe and efficient contact. This impedance requirement applies not only to the surface but also to the actuation mechanisms. The objective of this research is to develop inherently flexible actuator by realizing backdrivability. A class of hydraulic actuation called electro-hydrostatic actuator was applied to...
Contact-free estimation of the human somatosensory information is an essential skill for robots working in daily environments. The main objective of this paper is to develop a method for estimating muscle tensions without any sensors attached to the body. Muscle tension is an important information for evaluating physical load during motions. Existing approaches utilizing optimization techniques and/or...
The inertial parameters are important to generate motion patterns for humanoid robots. Conventional identification methods can be used to estimate these parameters; however they required the joint torque estimates that can be obtained by modeling of the transmission or by direct measurements. To overcome that issue we have recently developed a new method to estimate the inertial parameters of legged...
This paper deals with the imitation of human motions by a humanoid robot based on marker point measurements from a 3D motion capture system. For imitating the humanpsilas motion, we propose a Cartesian control approach in which a set of control points on the humanoid is selected and the robot is virtually connected to the measured marker points via translational springs. The forces according to these...
When simulating and controlling robot dynamics it is necessary to know the inertial parameters and the joint dynamics accurately. As these parameters are usually not provided by manufacturers, identification is then an essential step in robotics. In addition with the up coming wide-spreading of humanoid robots in the society the identification of humanoid dynamics has became mandatory to insure safety...
This paper presents a dynamics simulator that can handle complex robotic systems including position-controlled joints and closed kinematic chains. We first extend our prevous algorithm for linear-time forward dynamics algorithm to handle closed kinematic chains. The extended algorithm is formally presented for the first time. We then present another extension that allows position-controlled joints,...
Recently, many researchers on humanoid robotics are interested in quasi-passive-dynamic walking (quasi-PDW) which is similar to human walking. It is desirable that control parameters in quasi-PDW are automatically adjusted because robots often suffer from changes in their physical parameters and the surrounding environment. Reinforcement learning (RL) can be a key technology to this adaptability,...
This paper proposes a computational method of contact forces working between multibody system and environment in forward dynamics based on both the microbody-deformation model and macro contact model. The combination of them simultaneously prevents the simulation from excess penetration in micro contact model and chattering in macro contact model. The difficulty lies on how to absorb the difference...
Due to specialists doctors demand of quantifying some indicators to be used during examination, an original painless solution to estimate in-vivo the human joint passive rigidity is proposed and applied to the elbow joint. It is based on the use of a musculo-skeletal dynamics computation and a linear modelling of the human elbow joint dynamics. Movements acquisition is performed in a motion capture...
This paper discusses walking control of Theta, an innovative humanoid walking robot equipped with a double spherical hip joint and a knee joint switchable between active and passive operation mode, which has been developed at the University of Tokyo. The walking generator and controller are presented, including some implementation aspects. It is based on the inverted pendulum approach with the innovative...
The goal of the works presented in this paper is to study the feasibility of the in-vivo estimation of the musculo-tendon dynamics using an original approach. Contrarily to usual literature in this field the Hill-Stroeve based model parameters are estimated, and not only some global parameters with little physiological meaning. This estimation is based on the computation of the inverse kinematics...
This paper presents an online dynamical retouch method of referential motion patterns for humanoid robots. It converts transition sequences of desired posture and supporting state which are rough in terms of both time and space to a set of smooth piecewise functions applicable to actual robots with dynamical constraints taken into account. It is based on boundary condition relaxation method, and has...
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