As ordinary dual-axis driving mechanisms in X–Y directions, for example, commercially available X–Y stages with ball screws are familiar. However, such driving mechanisms have two stages, namely both upper and lower linear actuators, the latter of which must generate sufficient thrust to carry large weights, including that of the upper actuator mechanism, which has hampered efforts to achieve suitably fast and smooth driving motion due to the inertial force effect. It is also difficult to achieve a small and slimline driving mechanism with such overlapping two-stage structure. In these ordinary two-stage driving mechanisms, the motion of the X–Y stage can be disturbed by the cords of the upper actuator. In this research, we have considered the abovementioned problems, and propose a new omnidirectional driving gear mechanism that enhances its driving area from the normal X–Y plane to convex and concave curved surfaces respectively, and even various combinations of both. The smoothness of basic omnidirectional motion and effectiveness of the driving method of this proposed omnidirectional driving gear mechanism have been confirmed with several experiments involving our setups.
This paper proposes a virtual prosthetic hand (VH) and a virtual training system for controlling of electromyogram (EMG) prosthetic hands in virtual reality environment. The VH has human skin-like texture with 22 joints, and can realize a wide variety of human hand movements controlling each joint angle. Trainees can control it by using EMG signals and 3D position and posture measured from his or her forearm, and can perform training such as holding and moving virtual objects by controlling the VH voluntarily. In this paper, virtual box and block test (BBT) was developed as an example for operation training of the prosthetic hand. Experiments were conducted on five healthy subjects for five days. Manipulation ability of subjects were evaluated using seven indices calculated from the measured EMG signals and 3D position and posture during performing the virtual BBTs. Comparing the evaluated indices of the first and last days, four out of the seven indices show a significant difference at the 0.1% level, and one out of the seven at the 1% level. The results lead us to conclude that the proposed system could be used for operation training of EMG prosthetic hands.
In recent years, the social network has attracted attention as the system which causes the innovation, and various studies for researchers' networks have been carried out. This paper conducts social network analysis for a researchers' social network based on co-authorship in papers in the journal of RSJ. We investigate the 1,912 papers published from 1983 to 2010, which include 2,736 authors (nodes of the network) and 6,531 co-authorship (edges of the network). The network turns out to have general features as a complex network, such as scale-free structure, small-world structure, and cluster structure. We extract 710 core members from the network and analyze various centrality among them to show that some researchers demonstrate more importance in the network than their degrees. We also apply cluster analysis to the network to find 27 clusters in which researchers have close relationship, and give a coarse-grained representation of the clusters to clarify the adjacency among them.
Wall-climbing robots having holonomic and omni-directional mobility would enhance the manipulation performance of the mounted arm and enable it to execute various tasks on the surface of large structures. This study focuses on the wall-climbing robots having permanent magnet attractive units to stick to the surface of iron structure such as atomic reactors and discuss the development of a specific holonomic and omni-directional wall-climbing mechanisms. Basic driving mechanism of the wall-climbing robot is based on our former invention named Omni Disk which consists of multiple rollers attached to one side of a rotating disk and having a mechanism to direct the rollers to the same direction. We firstly discuss about the mechanical improvements of the Omni Disk to make it lightweight and low cost. We next discusses about four types of methods to attach permanent magnets to the wall-climbing robot and generates attractive force on the iron wall and select the best type based on the motion experiments about the constructed models. As the result of these considerations, we developed a holonomic and omni-directional wall-climbing robot named Vmax III which consists of three Omni Disks having permanent magnet at their center having the function to change the magnetic attractive force. By using the Vmax III, we studied about the relation among the magnetic attractive force of three Omni Disks, posture of the Vmax III and inclination angle of the iron wall and clarified the optimized distribution of the magnetic attractive force of the Omni Disks in different inclination of the iron wall.
In this study, psychological experiments are conducted to investigate human avoidance action characteristics in a phase where harm almost reaches human eyes in a human-robot coexistence system. A situation is set up in which the sharp end-effector tip of a robot suddenly approaches the eyes of a participant sitting in front of the robot. In the analysis of the experimental results, the avoidance reaction time is defined as the time interval from when the end effector begins to approach the participant's eyes until when the participant begins to move the head for avoiding the harm due to the end-effector tip. The results suggest that the avoidance reaction time does not depend on the type of work being performed but on the initial distance between the human's eyes and the approaching object.
In tissue engineering, it is important to manipulate cells quickly, so that we can construct 3D cell structure including blood pipe before it results in necrosis. In this paper, we newly propose the geometrically-constrained cell manipulation where the cell manipulation is achieved in 1D micro channel instead of 3D free space. The key idea is that cell motion with originally six degrees of freedom (d.o.f) in free space is constrained to one d.o.f by pushing cell into a channel. This manipulation scheme contributes to drastically reducing the manipulation time. Focusing on the positioning of cell in the micro channel, we confirmed that the position control is stable due to enough viscous force between cell and wall of the channel. The experimental system is precisely explained together with the manipulation algorithm. By using the developed system, we succeeded in cell positioning with 1[μm] resolution in average and with the maximum speed of 36.4[&mu ;m/s], by utilizing a high speed vision system, piezoelectric actuator (PZT), and polydimethylsiloxane (PDMS) chip including the micro channel whose diameter is slightly less than the cell to be handled.