Development of Flexible Spherical Actuator Controlled by Low-Cost Servo Valve and Embedded Controller

AbstractA wearable actuator needs to be flexible so as not to injure the human body. 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, we propose and test a flexible spherical actuator using the novel flexible pneumatic cylinders. The simple spherical actuator consists of two ring-shaped flexible pneumatic cylinders. They are intersected at right angle and are fixed on the base. The low-cost control system using the tested quasi-servo valves and an embedded controller (micro-computer) was also developed. The spherical actuator was also improved so as to suppress the vibration in control and to increase the stiffness of the actuator by changing the structure of the actuator. In addition, by using the quasi-servo valve controlled by the superior embedded controller, the flow rate of supply and exhaust could be controlled independently. As a result, the control performance could be improved using the improved spherical actuator and the quasi-servo valves controlled by the embedded controller with compensational method for exhaust

Mathematical and intelligent modeling of electropneumatic servo actuator systems

The pneumatic actuator represents the main force control operator in many industrial applications, where its static and dynamic characteristics play an important role in the overall behavior of the control system. Therefore, obtaining of accurate approach for modeling the pneumatic actuator is of prime interest to control system designers. In this paper a different methodologies for deriving and simulating the model of the pneumatic servo actuators controlled with proportional valves are presented. The model includes cylinder dynamics, payload motion, friction and valve characteristics

A Review of Smart Materials in Tactile Actuators for Information Delivery

As the largest organ in the human body, the skin provides the important sensory channel for humans to receive external stimulations based on touch. By the information perceived through touch, people can feel and guess the properties of objects, like weight, temperature, textures, and motion, etc. In fact, those properties are nerve stimuli to our brain received by different kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can stimulate these receptors and cause different information to be conveyed through the nerves. Technologies for actuators to provide mechanical, electrical or thermal stimuli have been developed. These include static or vibrational actuation, electrostatic stimulation, focused ultrasound, and more. Smart materials, such as piezoelectric materials, carbon nanotubes, and shape memory alloys, play important roles in providing actuation for tactile sensation. This paper aims to review the background biological knowledge of human tactile sensing, to give an understanding of how we sense and interact with the world through the sense of touch, as well as the conventional and state-of-the-art technologies of tactile actuators for tactile feedback delivery