So Shimooka

Estimation of Pressure Control Performance in Low-Cost Quasi-Servo Valve Using Embedded Controller

In our previous study, a small-sized and light-weight pressure control type quasi-servo valve was developed to reduce the burden of the user in a power-assisted system. The valve consists of inexpensive on/off control valves and embedded controller. In this study, the pressure control performances using four kinds of control scheme were investigated and compared by experiment and simulation. The frequencies up to 5 Hz were applied to the tested pressure control system. As an index of control performance, we used the mean absolute error. As a result, the sliding mode controller gave smaller error on the whole and PD controller gave the good performance in the higher frequency. It was confirmed that the introducing the dead zone to a control input and the lowering the supply pressure were effective to suppress the impulsive pressure change.

Analytical Model of Pipe Inspection Robot Using Flexible Pneumatic Cylinder

A pipe inspection robot is useful to reduce the inspection cost. In our previous study, a novel pipe inspection robot using a flexible pneumatic cylinder that can be driven even if it bends has been proposed and tested. The built-in pneumatic driving system using a tiny embedded controller and small-sized valves have also been proposed and tested to decrease the mass of the robot for increasing inspection area. In this chapter, in order to find out the optimal driving pattern and length of the robot, an analytical model of the pipe inspection robot is proposed. The model consists of two on/off control valves and a sliding mechanism which is composed of a flexible pneumatic cylinder.

Development of Tetrahedral Type Rehabilitation Device Using Flexible Pneumatic Actuators

Rehabilitation devices help to recover physical ability of patients. This study aims to develop a home rehabilitation device which can be safe to use while patients are holding it by hands. In the previous study, as a portable rehabilitation device, the flexible spherical actuator that was able to give motions to patients while handling it was developed. The device can give rehabilitation motion for upper limb by only changing the relative position of patient’s hands. However, the tested device cannot give absolute position for hands for rehabilitation of shoulders. In this study, we aim to develop a low-cost and simple home rehabilitation device for shoulder that can change absolute position of the device. In this paper, to realize position change of the flexible spherical actuator, the development of a tetrahedral type rehabilitation device using extension type flexible pneumatic actuators is described. The construction and the operating principle of the tested device is also described. The attitude control using the tested device and an embedded controller is also carried out. As a result, it can be confirmed that the absolute position of the object can trace the desired coordinate relatively well. 

Improvement of a Pneumatic Control Valve with Self-Holding Function

The purpose of this study is to develop a small-sized, lightweight and low-cost control valve with low energy consumption and to apply it to the assistive system. We have developed some control valves; a tiny on/off valve using a vibration motor, and an on/off valve with self-holding function. We have also proposed and tested the digital servo valve with self-holding function using permanent magnets and a small-sized servo motor. In this paper, in order to improve the valve, an analytical model of the digital servo valve is proposed. And the simulated results by using the analytical model and identified parameters were compared with the experimental results. Then, the improved digital servo valve was designed based on the calculated results and tested. As a result, we realized the digital servo valve that can control the flow rate more precisely while maintaining its volume and weight compared with the previous valve. As an application of the improved valve, a position control system of rubber artificial muscle was built and the position control was performed successfully.

Analysis and Simulation of Small-Sized Quasi-servo Valve Using Tiny On/Off Control Valve

Today, the care and welfare pneumatic equipment to support a nursing care and a self-reliance of the elderly and the disabled are actively researched and developed by many researchers. These wearable devices require many servo valves for multidegrees of freedom and precise control performance of the wearable actuator. The total weight of the wearable devices increases according to the degree of freedom. In our previous study, a small-sized and lightweight pressure control-type quasi-servo valve was developed t. The valve consists of two on/off control valves and an embedded controller. In this study, the quasi-servo valve composing of much smaller-sized (40 % in mass, 42 % in volume) on/off valves is proposed and tested. The analytical model of the tested valve is proposed and the system parameters are identified. As the result of the comparison between experimental results and simulated, it was confirmed that the proposed analytical model and the identified system parameters were valid.