Artificial Rubber Muscle Research Articles

Development and Application of Shape-Memory Polymer and Alloy Composite Sheets

The authors previously developed a flexible and multi-degree-of-freedom pneumatic artificial rubber muscle that uses shape-memory polymer (SMP) sheets with an embedded electrical heating wire. The bending direction and initial shape of the muscle can be changed by utilizing the large difference in the elastic modulus below and above the glass transition temperature, shape fixity, and shape recovery of SMPs. In this study, to improve performance, we propose a shape-memory composite (SMC) sheet that consists of SMP sheets with an embedded shape-memory alloy (SMA) wire used as an electric heating wire. The mechanical properties of the previously developed SMP sheets and the proposed SMC sheets are compared through shape recovery, bending, and tensile tests using prototypes. The motion of the artificial muscle with various samples attached is evaluated through an isometric test and bending angle measurements. The experimental results confirm that the use of the SMA wire improves the production reproducibility and shape recovery of the SMP sheets without degrading other mechanical properties or actuator performance.

Development of Pneumatic Artificial Rubber Muscle Using Segmented Shape-Memory Polymer Sheets

We have developed a pneumatic artificial rubber muscle using two shape-memory polymer (SMP) sheets. We attached the SMP sheets to a linear pneumatic artificial rubber muscle. Utilizing the large difference in the elastic modulus below and above the glass transition temperature, the shape fixity and shape recovery of SMPs, the bending direction and the initial shape can be changed. In this study, in order to increase the bending motion range, we developed a segmented SMP sheet with embedded electrical heating wires, and evaluated its mechanical properties using bending and tensile tests. Moreover, we attached such sheets to an artificial muscle and evaluated the bending motion. Bending tests showed that segmenting the SMP sheets greatly reduced their bending stiffness. In tensile tests at temperatures below the glass transition temperature, it was found that the artificial muscle with the attached sheet withstood high elongating loads without failure. Attachment of such segmented SMP sheets to an artificial muscle resulted in an increased bending angle. Through isotonic and isometric tests, we showed that the prototype actuator could bend in two directions.

Two-link Manipulator Driven by a Pair of Antagonistic Rubber Artificial Muscle

Pneumatic rubber artificial muscles have been extensively researched as a driving device capable of soft movements that are compatible with humans, and are expected to be applied to human friendly robots. However, it is difficult in principle to achieve high-precision positioning and high-rigidity position retention due to low stiffness and delayed response as a result of air compressibility. Normally, a 2-link manipulator requires 4 (2 pairs) artificial muscles, but here, by attaching two MR brakes to each axis and switching the drive shaft, a manipulator that controls a 2-link manipulator with 2 (1 pair) artificial muscles, is proposed.

Peristaltic Mixing Pump Based on Bowel Peristalsis Using Pneumatic Artificial Rubber Muscles and Prospects for Practical Applications

This letter proposes a peristaltic mixing pump based on bowel peristaltic motion driven by soft pneumatic actuators. Furthermore, various practical applications using the peristaltic mixing pump are introduced, such as mixing and conveying processes for solid rocket fuel production and lifting conveyance of excavated soil and sand during the construction process. First, the bowel peristaltic motion mechanism is introduced from the anatomical perspective. Next, the construction of the peristaltic mixing pump and its actuation mechanism are presented. Finally, the application and prospects of peristaltic mixing pumps are described.

Development of Variable Viscoelastic Joint Module Performance Evaluation and Proposal of Application Examples

With the diversification of robots, modularization of robots has been attracting attention. In our previous study, we developed a robot that mimics the principle of human joint drive using a straight-fiber-type pneumatic rubber artificial muscle (“artificial muscle”) and a magnetorheological fluid brake (“MR brake”). The variable viscoelastic joints have been modularized. Therefore, this paper evaluates the basic characteristics of the developed Joint Module, characterizes the variable viscoelastic joint, and compares it with existing modules. As basic characteristics, we confirmed that the Joint Module has a variable viscoelastic element by experimentally verifying the joint angle, stiffness, viscosity, and tracking performance of the generated torque to the command value. As a characteristic evaluation, we verified the change in motion and response to external disturbances due to differences in driving methods through simulations and experiments and proved the strength of the variable viscoelastic joint against external disturbances, which is a characteristic of variable viscoelastic joints. Based on the results of the basic characterization and the characterization of the variable viscoelastic drive joint, we discussed what kind of device the Joint Module is suitable to be applied to and clarified the position of the variable viscoelastic joint as an actuator system.

Verification of Characteristics of McKibben Type Artificial Rubber Muscle Considering Material Properties of Muscle End Contact Surface

Verification of Characteristics of McKibben Type Artificial Rubber Muscle Considering Material Properties of Muscle End Contact Surface

Modeling the hysteresis characteristics of McKibben type artificial rubber muscle based on rubber physical characteristics

Modeling the hysteresis characteristics of McKibben type artificial rubber muscle based on rubber physical characteristics

Development of a Knee Joint Assistive Orthosis Using Pneumatic Rubber Artificial Muscles for Maintaining a Half-Sitting Posture

Development of a Knee Joint Assistive Orthosis Using Pneumatic Rubber Artificial Muscles for Maintaining a Half-Sitting Posture

平面リンク機構と空気圧ゴム人工筋肉を用いた歩行リハビリ装置の試作および評価

In Japan today, the aging of the population is progressing, and there is a concern that the number of elderly people who will have a trouble walking will increase. Rehabilitation of medical and welfare services are required to solve this problem, but it will be concerned to be difficult to deal with this problem due to a shortage of human resources and an increase in the number of elderly people. Therefore, there is a need to develop a walking rehabilitation device that can be handled by the elderly alone. Authors has been developing walking aids and rehabilitation devices using linkages. These devices do not require a control system or an external power source, and are designed with an emphasis on simplification and cost reduction of the devices. However, if it is designed with only a mechanism, the operation of the device may become unstable, which has been a problem. Therefore, authors aim to improve the stability of the device by newly using a pneumatic rubber artificial muscle as an actuator and assisting the operation of the mechanism. In this research, on the premise that a pneumatic rubber artificial muscle is used as an actuator, authors will develop a device that rehabilitates the interlocking movement of three leg joints with a one degree-of-freedom link mechanism. In this research, Authors will use an actual machine to evaluate whether the characteristics of the artificial muscle, such as flexibility, high output density, and contractile motion, are suitable for walking rehabilitation equipment.

Development of walking rehabilitation device using planar link mechanism and pneumatic rubber artificial muscle

In Japan today, the aging of the population is progressing, and there is a concern that the number of elderly people who will have a trouble walking will increase. Rehabilitation of medical and welfare services are required to solve this problem, but it will be concerned to be difficult to deal with this problem due to a shortage of human resources and an increase in the number of elderly people. Therefore, there is a need to develop a walking rehabilitation device that can be handled by the elderly alone. Authors has been developing walking aids and rehabilitation devices using linkages. These devices do not require a control system or an external power source, and are designed with an emphasis on simplification and cost reduction of the devices. However, if it is designed with only a mechanism, the operation of the device may become unstable, which has been a problem. Therefore, authors aim to improve the stability of the device by newly using a pneumatic rubber artificial muscle as an actuator and assisting the operation of the mechanism. In this research, on the premise that a pneumatic rubber artificial muscle is used as an actuator, authors will develop a device that rehabilitates the interlocking movement of three leg joints with a one degree-of-freedom link mechanism. The aim of this study is to verify whether the characteristics of artificial muscles such as flexibility, high output density, and contractile movement are suitable for walking rehabilitation equipment.

A Study on Development and Control of Antagonistic Muscle Joint Structure Using Pneumatic Rubber Artificial Muscle and Non-Circular Pulley

A Study on Development and Control of Antagonistic Muscle Joint Structure Using Pneumatic Rubber Artificial Muscle and Non-Circular Pulley

Characteristics of Pneumatic Artificial Rubber Muscle Using Two Shape-Memory Polymer Sheets

We have developed a pneumatic artificial rubber muscle having a bending direction that can be changed using two shape-memory polymer (SMP) sheets, the stiffness of which depends on the temperature. In the present study, we attached two SMP sheets with embedded electrical heating wires to both sides of a pneumatic artificial rubber muscle in order to realize multidirectional actuation and evaluated the basic characteristics of the artificial muscle. The actuator is based on the design of a conventional curved-type artificial rubber muscle. Since only a heated SMP sheet becomes soft, the rigid SMP sheet inhibits the extension of the side of the actuator. Therefore, bending motion can be induced when air is supplied to the internal bladder. By controlling the temperature of the SMP sheets, the bending direction of the prototype actuator could be changed. Namely, three kinds of motions, such as two-directional bending and axial extension, became possible. Moreover, we improved the manufacturing method and the structure of the artificial muscle, such as the stitching method and the SMP sheet thickness, and evaluated the characteristics of the two-directional bending and the axial extension motions of the prototype actuator. We also calculated the theoretical values and compared these values with the experimental results. Furthermore, we examined the application of the actuators to a robot hand. Using the two-directional motion of the actuator, the proposed robot hand can grasp either small or large objects. The experimental results conducted using this prototype confirm the feasibility of the newly proposed actuator.

Estimation for Characteristic of Short-Length McKibben Type Artificial Rubber Muscle Considering Initial Shape

Estimation for Characteristic of Short-Length McKibben Type Artificial Rubber Muscle Considering Initial Shape

Development of a robot hand based on the musculoskeletal system using pneumatic rubber artificial muscle

Development of a robot hand based on the musculoskeletal system using pneumatic rubber artificial muscle

Analysis of a New Artificial Muscle Type Dynamic Orthosis for Wrist Joint Disease Using a Three-dimensional Motion Analyzer.

ABSTRACTObjectives:Recently, the dart-throwing motion (DTM) has attracted attention as a functional direction of wrist joint motion. Consequently, we devised a new artificial muscle-type dynamic orthosis (Dynamic Traction Splint by Artificial Muscle, DTSaM) to reproduce DTM. This study analyzed the automatic motion of the wrist joint using a three-dimensional motion analysis system to assess how closely the DTSaM replicates DTM.Methods:The DTSaM orthosis incorporates two McKibben-type rubber artificial muscles, and measurements were performed using image analysis software and a three-dimensional motion analysis system. The wrist radial angle (WRA) was defined as the angle between the line connecting the head of the index finger metacarpal to the radial styloid process and the line connecting the radial styloid process to the lateral epicondyle of the humerus. WRAs were investigated from 60° of palmar flexion to 60° of dorsiflexion.Results:For dorsiflexion, comparisons of radial deviation and wrist ulnar angle (WUA) between the motion obtained using the DTSaM orthosis and active DTM showed a significant difference (P <0.05) at 30° and 60°, respectively. For palmar flexion, the same comparison showed a significant difference for both the ulnar and radial deviations (30°, P <0.05; and 60°, P <0.01, respectively). Furthermore, WUA showed a significant difference at 50° (P <0.05). Intraclass correlation coefficient analyses yielded good reliability with an average value of ≥0.8.Conclusion:The DTSaM orthosis produces a motion similar to the DTM. It is hoped that the use of the DTSaM orthosis will help to shorten the treatment period for patients with wrist disease.

Development of components in icosahedral self-distortion robot using bending pneumatic rubber artificial muscles. And robot driving experiments.

Development of components in icosahedral self-distortion robot using bending pneumatic rubber artificial muscles. And robot driving experiments.

Development and control of cord-like manipulator using bending type pneumatic rubber artificial muscles

Development and control of cord-like manipulator using bending type pneumatic rubber artificial muscles

A Sliding Mode Controller Using an LS-SVM Model for a Water-Hydraulic Artificial Rubber Muscle

We describe a sliding mode controller design for an artificial rubber muscle driven by tap-water pressure. The hysteretic characteristics of this water-hydraulic artificial rubber muscle (WARM) often deteriorate its control accuracy. To cope with this complicated hysteresis, a modeling approach based on the least squares support vector machine (LS-SVM) with nonlinear kernel functions is first applied to a WARM. By employing this LS-SVM-based WARM model, a sliding mode controller is then derived for the WARM drive system. We verify the control performance of the proposed controller and compare its tracking accuracy with our previously developed controller through experiments.

Exploring solutions to assist finger rehabilitation with flexibility

Motivated by the need to help those people whose hands and fingers are incapacitated due to injuries or birth defects, the curved-type pneumatic artificial rubber muscle is discussed in this paper, which is shown to be more flexible and convient than traditional motor-driven soft robotic devices for hand rehabilitation and assistance if designed correctly. When people are injured, their finger joints become stiff and not be able to fully flex. Thus, an assisting device is needed. Machine-based hand exoskeleton for rehabilitation uses hardware and hard components, which carries the risk of furthering the injuries when the exoskeleton breaks or exceeds its driving capacity. In comparison, air-pneumatics driven hand rehabilitation device composed of flexible air muscle not only curves smoother, but also weighs lighter and can be designed as a carry-on, providing safety, utility, and comfortability. Several experiments and researches were run to determine the best structure and air-pressure to suit such purposes. Instead of the traditional button-pressing panel, Neuron-Muscular Transmission (NMT) - a detectable chemical signal - is used to activate the inflation and deflation of the device, therefore making the device thought-driven. In the end, Flexible Pneumatic System (FPS) is created to improve hand rehabilitation and supportive exoskeleton devices.

Twisted Rubber Variable-Stiffness Artificial Muscles.

Variable-stiffness artificial muscles are important in many applications including running and hopping robots, human–robot interaction, and active suspension systems. Previously used technologies include pneumatic muscles, layer and granular jamming, series elastic actuators, and shape memory polymers. All these are limited in terms of cost, complexity, the need for fluid power supplies, or controllability. In this article, we present a new concept for variable-stiffness artificial muscles (the twisted rubber artificial muscle, TRAM) made from twisted rubber cord that overcomes these limitations. Rubber cord is inexpensive, readily available, and inherently compliant. When an extended piece of rubber cord is twisted, the tensile force it exerts is reduced and its stiffness is altered. This behavior makes twisted rubber ideal for use as an artificial muscle, because its output force and natural stiffness are both controllable by varying twist angle. We investigate the behavior of four types of rubber cord and evaluate which type of rubber allows for the greatest reversible reduction in average stiffness (fluoroelastomer [FKM standard] rubber, 56.42% reduction) and initial stiffness (silicone rubber, 92.62%). Tensile force and stiffness can be further altered by increasing the twist angle of the artificial muscle beyond a threshold angle, which initiates nonlinear buckling behavior. This, however, can cause plastic deformation of the artificial muscle. Using a single TRAM, we show how the equilibrium position and natural frequency of a system can be simultaneously altered by controlling twist angle. We further demonstrate independent position and stiffness control of a functional robotic arm system using an antagonistic pair of TRAMs. TRAMs are ready for immediate inclusion in a wide range of robotic systems.