Using the pattern of the peristaltic movement of an earthworm, a microrobot was developed for traveling in a tube using a magnetic fluid. In this microrobot, a cell equivalent to a segment of the earthworm is composed of a natural rubber tube into which a water-based magnetic fluid is sealed up. The cells are connected with rod-like elastic bodies of natural rubber. It was confirmed that this robot can travel in an acrylic tube (inner diameter: 12 mm, outer diameter: 14 mm) by providing a shifting magnetic field from the exterior. This article will describe how our microrobot is propelled, the mechanism of its propulsion, and the analytical results of the propulsive force.

Piezoelements used in robotics require large elasticity and extensibility to be installed in an artificial robot skin. However, the piezoelements used until recently are vulnerable to large forces because of the thin solid materials employed. To resolve this issue, we utilized a natural rubber and applied our proposed new method of aiding with magnetic and electric fields as well as filling with magnetic compound fluid (MCF) and doping. We have verified the piezoproperties of the resulting MCF rubber. The effect of the created magnetic clusters is featured in a new two types of multilayered structures of the piezoelement. By measuring the piezoelectricity response to pressure, the synergetic effects of the magnetic clusters, the doping and the electric polymerization on the piezoelectric effect were clarified. In addition, by examining the relation between the piezoelectricity and the piezoresistivity created in the MCF piezo element, we propose a hybrid piezoelement.

This article describes a mathematical model of a pneumatic artificial muscle reinforced by straight fibers. The pneumatic artificial muscle is lightweight and high power. In addition, it is possible for it to emit exhaust into the atmosphere because the transmission medium of its energy is air, and it needs neither a tank nor maintenance like hydraulic equipment. In addition, safety to a person and the environment is high because the base of the actuator is a soft polymeric material even if damage to the artificial muscle is caused. On the other hand, because the device is composed of a thin film cylinder, and is easily influenced by outside power for the conversion of the volume change in rubber into physical contraction axially, and its passive character is strong, precise positional control is difficult. However, the living thing that has a verbose degree of freedom enables minute motion and walking, etc. by skillfully adjusting to avoid impedance, because it understands its own muscular characteristic beforehand. Similarly, it is thought that the precise positional control is possible by understanding the characteristics of an artificial muscle beforehand. In this research, it is assumed that the expansion shape of the pneumatic artificial muscle that we developed from the pressure distribution is equivalent to the centenary curve, and its model is based on dynamic balance. The result shows the effectiveness of control of an artificial muscle that uses highly accurate calculations and models.