Human's joint structure consists of ligaments, bones and muscles. This structure is strong to the load-stress applied to the joint. In this research, we propose a method as the engineering application of the mechanism of ligaments and bones. In the proposed method, a fiber-belt is used as a substitute of ligaments. Fibers have two types of states: a tensioned state and a relaxed state. We determined the condition under which the fiber generates tension, and realized joint restraint by multiple fibers. In the case that the center of rotation changes, the joint is constrained by using the fiber tensions and the joint surface reaction forces. We developed a rolling joint by the fiber constraint method. In the developed rolling joint has the changing rotational center position due to the rolling motion. Cycloid curves and trochoid curves are used for articular contact surface design. We confirmed that the rolling joints can be realized with the proposed fiber constraint method.
In this research, we examine about acceleration coupling with velocity on extended operational space of a kinetic redundant manipulator. The coupling with velocity appears as a translating a dynamic manipulability polyhedron. The extended operational space is consisted of operational space and redundant space. Redundant space is null space of operational space that is spanned by column vectors of the Jacobi matrix. We clarify translating the dynamic manipulability polyhedron by deriving basis vectors of translating vector and vertex vectors of dynamic manipulability polyhedron that are independent of velocity on the extended operational space. Appropriateness of the translation of dynamic manipulability polyhedron is confirmed by calculating the dynamic manipulability polyhedron with various velocities on simulation.
For the decommissioning of the Fukushima Daiichi Nuclear Power Station, the primary containment vessel (PCV) internal survey for fuel debris spreading has been needed. The survey has been implemented using remotely operated robots. Localization of the robots during their operation is necessary to adjust sensor positions. In this research, we propose a localization method which combines a stereo camera-based method for absolute localization and a periodic structure tracking method for relative localization. The position accuracy for proposed method was verified in a mock-up test field, and it was confirmed that the position accuracy satisfied the required accuracy of 30[mm].
A teleoperation system with a haptic device can present a reaction force generated when a robot contacts an environment. However, expressing an impact force resulting from tapping a hard object is difficult in a haptic device. There is a method of rendering a hard object by overlaying vibrations, but an index of hardness perception is necessary to determine the output of vibrations so as to be equivalent to the hardness perceived by the impact force. Therefore, in this study, based on previous studies, we propose an index of hardness perception using the bandpass filter that imitates the response characteristics of Pacinian corpuscles and the collision speed, and evaluated by the hardness rendering in a haptic device. As a result of experiments, we showed that there is a correlation between the hardness rendered by the haptic device and the proposed index of hardness perception. In addition, we showed a hardness rendering method using the index in a teleoperation system and examined the effect of the method. As a result, we confirmed that the hardness according to the index can be rendered in real time in a haptic device even if an object is unknown.