Flexible Artificial Muscle Actuator Using Coiled Shape Memory Alloy Wires

The suction dynamics of axial piston pumps become more critical if the pump is to be used at high speeds. In order to prevent air-release and cavitation from occurring within the pump it is necessary to pressurise the pump inlet. As the speed of a pump increases so will the required boost pressure, due to the extra losses incurred through the suction line and portplate at the higher flowrates. However, the lack of data regarding axial piston pump behaviour at high speeds creates problems for the system designer in telecting suitable boost conditions and for the pump designer in selecting the portplate configuration that is required to reduce fluid-borne-noise levels. This paper discusses the suction performance of piston pumps, and presents experimental and simulation results exploring the behaviour of a high-speed axial-piston pump. Different air-release and cavitation models that are suitable for simulation studies are investigated

The suction dynamics of positive displacement axial piston pumps

A McKibben artificial muscle consisting of a rubber tube and a mesh sleeve made from fibers is a promising actuator as an artificial muscle because of its high power, low weight, and flexibility. However, an external pressure sensor or an expensive electro/pneumatic regulator is generally required to control the pneumatic pressure to drive the actuator. A novel smart McKibben-type artificial muscle with a pressure-sensing function has been proposed and developed in this study. One fiber on the sleeve of the actuator is converted from a normal to a conductive material. The applied pressure is estimated by observing the electrical resistance of the conductive fiber. Therefore, the fiber works as both a sensor and an actuator element. The fabrication process of the smart artificial muscle is established in this report, and the basic characteristics are clarified. Moreover, a compact driving control system of the smart artificial muscle, which uses a small rotary pump without external sensors, electro/pneumatic regulator, or valves, is proposed.

New concept and fundamental experiments of a smart pneumatic artificial muscle with a conductive fiber

This study presents the design of a pneumatic artificial muscle with integrated soft optical sensing for estimation of muscle contraction length and contraction force. Each optical sensor uses an l...

Optical Sensor-Embedded Pneumatic Artificial Muscle for Position and Force Estimation.

Pneumatic artificial muscles (PAMs) are one of the most famous linear actuators in bio-inspired robotics. They can generate relatively high linear force considering their form factors and weights. Furthermore, PAMs are inexpensive compared with traditional electromagnetic actuators (e.g. DC motors) and also inherently light and compliant. In robotics applications, however, they typically require external sensing mechanisms due to their nonlinear behaviors, which may make the entire mechanical system bulky and complicated, limiting their use in simple systems. This study presents the design and fabrication of a low-cost McKibben-type PAM with a self-contained displacement and force sensing capability that does not require any external sensing elements. The proposed PAM can detect axial contraction force and displacement at the same time. In this study, the design of a traditional McKibben muscle was modified to include an inductive coil surrounding the muscle fibers. Then, a thin, soft silicone layer was coated outside of the muscle to protect and hold the sensing coil on the actuator. This novel design measures coil inductance change to determine the contraction force and the displacement. The process can be applied to a variety of existing McKibben actuator designs without significantly changing the rigidity of the actuator while minimizing the device's footprint.

Design of a bio-inspired pneumatic artificial muscle with self-contained sensing

Development of Smart Inner Diameter Sensor for Position Control of Mckibben Artificial Muscle

Today, a welfare pneumatic equipment to support a nursing care and to execute a rehabilitation for the elderly and the disabled are actively studied and developed by many researchers. The total weight of a wearable device increases according to the degree of freedom of the device. In this study, we proposed and tested a flexible extension type actuator with longer displacement. The maximum displacement of about 270 mm (235%) can be obtained. Using the actuator, the flexible robot arm was developed. As a result, we confirmed that the robot arm is able to extend straight and bend in any directions. An analytical model of the arm was proposed to predict the attitude of the arm. To control the actuator, the quasi-servo valve with built-in driving circuit using an embedded controller was also proposed and tested. In addition, the portable rehabilitation device using the robot arm, three quasi-servo valves and three displacement sensors was developed.

Development of portable rehabilitation device using flexible extension type soft actuator with built-in small-sized quasi-servo valve and displacement sensor

In a pneumatic driving system, a servo valve is most expensive equipment compared with pneumatic actuators. In a wearable driving system, the mass and size of a valve also becomes serious concern. The purpose of this study is to reduce the burden of the user by using a small and light-weight quasi-servo valve that consists of inexpensive on/off valves and an embedded controller. The relation between input duty ratio and output flow rate of the valve is nonlinear. In the previous study, a pressure control type quasi-servo valve using a pressure transducer was also developed. However, the cost of the valve was increased. In this paper, to develop a lower-cost valve with good controllability, the flow rate control type quasi-servo valve by compensating the input duty-ratio of the valve is proposed and tested. The performance of the tested valve was also investigated. As a result, the valve can generate the proportional output flow rate according to the input voltage.

Masataka Yoneda

Papers

Development of Smart Inner Diameter Sensor for Position Control of Mckibben Artificial Muscle

Development of portable rehabilitation device using flexible extension type soft actuator with built-in small-sized quasi-servo valve and displacement sensor

Development of Flow Rate Control Type Quasi-Servo Valve Using Small-Sized On/Off Valves

Development of Low-cost Intelligent Wearable Motion Sensing Device Using Embedded Controller