Development and control of flexible spherical actuator using flexible pneumatic cylinders

The purpose of our study is to develop a flexible and lightweight actuator which can be safe enough to be attached to the human body, and to apply it to a flexible mechanism and rehabilitation device. New types of flexible pneumatic actuator that can be used even if the actuator is deformed by external force have been developed in our previous studies. In this paper, a flexible spherical actuator using the novel flexible pneumatic cylinders is proposed and tested. The simple-structured spherical actuator consists of two ring-shaped flexible pneumatic cylinders. They are intersected at right angle and are fixed on the base. The control system using the quasi-servo valves developed in our previous study and a micro-computer is also developed. In addition, the spherical actuator is improved so as to suppress the vibration in control and to increase the stiffness of the actuator by changing the structure of the actuator. As a result, a large working area of the actuator could be obtained using the tested simple-structured spherical actuator. The control performance could be improved using the improved actuator and the improved control method.