This paper presents a method to create fish-like robots with tensegrity systems and describes a prototype modeled on the body shape of the rainbow trout with a length of 400 mm and a mass of 102 g that is driven by a waterproof servomotor. The structure of the tensegrity robot consists of rigid body segments and elastic cables that represent bone/tissue and muscles of fish, respectively. This structural configuration employing the tensegrity class 2 is much simpler than other tensegrity-based underwater robots. It also allows the tuning of the mechanical stiffness, which is often said to be an important factor in fish swimming. In our robot, the body stiffness can be tuned by changing the cross-section of the cables and their pre-stretch ratio. We characterize the robot in terms of body stiffness, swimming speed, and thrust force while varying the body stiffness i.e., the cross-section of the elastic cables. The results show that the body stiffness of the robot can be designed to approximate that of the real fish and modulate its performance characteristics. The measured swimming speed of the robot is 0.23 m/s (0.58 BL/s), which is comparable to other fish robots of the same type. Strouhal number of the robot 0.54 is close to that of the natural counterpart, suggesting that the presented method is an effective engineering approach to realize the swimming characteristics of real fish.

We propose a novel adsorption pad for wall climbing robot and irregular surface object using capillary force and water sealing. We call this adsorption pad as Super Wet Adsorption pad. The SWA pad has a porous part and a capillary part. The porous part is made by salt reaching method. When the SWA pad adsorbs to the wall which some sand and dust are attached, water comes from the porous part to avoid vacuum breaking. The capillary part is connected to the porous part to supply and stock the water. In this paper, we show the design of the porous part and the capillary part, fabrication process of each parts, and perform the evaluation experiment of the capillary force and adsorption of uneven surfaces, demonstration of wall climbing robot and adsorption of irregular surface foods.

Division of Labor Control is advanced function for distributed autonomous robotic systems. Many studies focussing division of labor control inspired biological phenomenon have been reported. However, the optimality is not discussed because decentralized control is typically complicated. In this study, we propose the division of labor control method for robot group that enable adaptively select whether homogeneous state or heterogeneous state against working conditions and address the optimality by mathematical analysis. To evaluate the effectiveness of the proposed method, the computer simulations are carried out and we confirm that robot group implemented the proposed method inevitably organize the division of labor state with group performance improvement.

This paper proposes a control method of vehicle cooperative behavior in an intersection and junction without infrastructures such as a signal system, a road-vehicle communication system, and so on. The vehicle cooperative behavior enables vehicles to pass through an intersection one by one or to interflow at junction one by one without vehicle collision like a weaving and zipping manner. These behaviors are achieved by generating a special-temporal pattern of a reaction diffusion system, where a mutual communication between vehicles is realized only by TVC device. The mutual communication between vehicles can be expressed in the diffusion system of a certain morphogen so that only simple broadcasting communication could be enough for vehicle communication. Van der Pol model is used as one of the reaction diffusion system. Finally, the proposed algorithm for vehicle cooperative behavior is experimentally verified using actual autonomous mobile robots.