Low back pain is often suggested as a problem to be prevented. Focusing on workers, it is difficult to work while avoiding Back pain. For example, in an agriculture area, the burden on the body is large during crop harvesting and loading operations. At the factory, the same is true for the work of transporting heavy objects and the work of keeping the waist. In this study, we focus on nursing behavior. In nursing behavior overburden action is many shown, it is proposed as one of the reasons for having to leave the job. We have been focusing on corsets to reduce back pain and have developed pneumatic corsets that can switch compression force. By switching the compression force, it is possible to eliminate the need for attachment and detachment, and to avoid muscle loss due to continued wearing. In addition, it can be expected to follow the human's movement by air pressure. In conventional researches, effective results have been obtained in myogenic potential evaluation experiments using the basic structure. In this paper, we propose a basic experimental method to evaluate from the viewpoint of both mechanics and subjectivity for the miniaturization of the system for use in the nursing field and the optimization of the corset structure. In this paper, we propose a new corset structure for miniaturization of the system used in the nursing field, and evaluate it experimentally from both viewpoints of mechanics and subjectivity.

The McKibben artificial muscle, which is one of soft actuators and consists of a rubber tube and a sleeve of reinforcement fibers, has the features of flexibility and lightweight. For increasing the convenience of the McKibben artificial muscle, attaching the sensor function to the artificial muscle is required. However, general rigid sensors hinder the advantage of the McKibben artificial muscle. Therefore, smart artificial muscles integrated with sensors have been developed.

In this paper, we describe the fabrication method of artificial muscles having enameled wires forming coiled-shape and working as both reinforcement fibers for actuation and a displacement sensor. When the artificial muscle is driven, since the shape of the coil changes, the displacement of the artificial muscle can be estimated by measuring the inductance of the coil. The fabrication process of the smart artificial muscles using a braiding machine is proposed. By this fabrication process, it is possible to change the braiding angle of the reinforcement fibers, and both the contraction-type and the extension-type artificial muscles with the sensor function can be manufactured by the same process. In addition, on the contraction-type smart artificial muscle, for increasing the sensor output, magnetic fluid is used as the working fluid.

Magnetorheological fluids (MR Fluids) are suspensions which consist of soft magnetic particles and base liquid. By applying magnetic field, the particles make chain-like structure and rheological properties of the MR fluids show remarkable change. This characteristic is suitable for constructing control devises. In those devices, a MR fluids valve is one of promising devises. Because, the MR fluids valve can be controlled without mechanical mechanism, so the MR fluids valve has excellent reliability. In case of applying the MR fluids valve to controlling a hydraulic actuator, pressure (thrust) control is easy, but speed control is difficult. Because, the MR fluids have Bingham plastic characteristics, so pressure drop due to flow velocity is small compared to that due to yield shear stress. So, a rectangular pulse wave control based on pulse width modulation (PWM) control method taking account of yield shear stress of MR fluids and time constant of MR fluids valve is proposed and simultaneous control of speed and thrust of the hydraulic actuator with MR fluids valve is performed.