Thin McKibben Muscles Research Articles

A Soft Crawling Robot That Can Self-Repair Material Removal and Deep Lengthwise Cuts, Actuated by Thin McKibben Muscles

A Soft Crawling Robot That Can Self-Repair Material Removal and Deep Lengthwise Cuts, Actuated by Thin McKibben Muscles

Funabot-Suit: A bio-inspired and McKibben muscle-actuated suit for natural kinesthetic perception

In recent years, there has been extensive utilization of actuators driven by artificial muscles in wearable devices. However, the muscle distribution configurations of most wearable devices have been specifically designed and are difficult to generalize. Consequently, wearable devices that allow direct installation of actuators onto existing clothing are better suited for a wider range of application scenarios. This letter presents the development and evaluation of Funabot-Suit, a human muscle configuration inspired wearable assist device that employs McKibben artificial muscles to induce natural kinesthetic perception in the wearer’s torso. By integrating thin McKibben muscles into an existing motion capture suit, the Funabot-Suit is capable of generating four fundamental motions: forward and backward bending, and left and right twisting. The suit’s performance was assessed through experiments involving three subjects who wore the suit while standing and seated, with the subjects reporting the direction of their kinesthetic perception. The subjects also rated the perceived ease of kinesthetic perception direction on a five-point scale. Our results demonstrate that the Funabot-Suit successfully induces kinesthetic perceptions for the wearer, with a one hundred percent detection ratio for accurate responses in the command direction across all subjects and positions. We observed variations in the sensitivity of left–right and up-down sensations, which can be attributed to the positioning of artificial muscles and individual differences.

Active textile: woven-cloth-like mechanisms consist of thin McKibben actuators

ABSTRACT Pneumatic artificial muscles have some advantages. Especially, the flexibility of artificial muscles contributes to compose novel mechanisms. Authors succeeded in manufacturing novel soft mechanisms that are composed of only woven artificial muscles and strings. We called this mechanism active textile. The structure is uniformed with woven artificial muscles; nevertheless, the forms and movements of mechanisms are diverse. We aim to establish a design method for these active textiles. We reported that deformations of active textiles are changed by woven structures. In addition to that, wefts' characteristics such as cross-sectional shape, bending stiffness and elasticity determine the characteristic of a textile. Deformations of active textiles are caused by the contraction and the expansion of thin McKibben muscles. In this paper, authors focus on the contraction and curvature deformation of the active textile due to the drive of the artificial muscles.We fabricated active textiles with different wefts and different weave structures.Contraction and bending deformations of active textiles in the warp and weft directions are assumed geometrically. In addition, we verified the validity by experiments.

Switching Model Predictive Control for Thin McKibben Muscle Servo Actuator

Dynamic characteristics and control of thin McKibben muscle (TMM) have not yet been fully investigated, especially on the translational antagonistic pair system. Therefore, the objective of this study is to propose a Switching Model Predictive Control (SMPC) based on a Piecewise Affine (PWA) system model to control a translational antagonistic-pair TMM servo actuator. A novel configuration enables the servo actuator to achieve a position control of 40 mm within a small footprint. The result shows that the feedback system gives minimal steady-state errors when tracking staircase and setpoint references ranging from 0 to 3.5 cm. The controller also produces better transient and steady-state responses than our previously developed Gain-scheduled Proportional–Integral–Derivative (GSPID) controller. The evidence from this study suggests that a predictive control for a TMM servo actuator is feasible.

Simple Neural Network Compact Form Model-Free Adaptive Controller for Thin McKibben Muscle System

This paper proposes a simple neural network compact form model-free adaptive controller (NNCFMFAC) for a single thin McKibben muscle (TMM) system. The main contribution of this work is the simplification of the current neural network (NN) based compact form model-free adaptive controller (CFMFAC), which requires only two adaptive weights. This is achieved by designing a NN topology specifically to enhance the CFMFAC response. The prominent control parameters of the CFMFAC are combined and one adaptive weight is used for self-tuning, while the second adaptive weight is used to minimize the offset at each operating point. Hence the issues of redundant adaptive weights in complex neuro based CFMFACs and slow response of the CFMFAC are significantly addressed. The idea is proven in three ways: analytically, simulation on a nonlinear system and experiments on a TMM platform. Experimental results demonstrate the superiority of the proposed method over the conventional CFMFAC is confirmed by a 76% improvement in the convergence speed and a 60% reduction in root mean square error (RMSE). It is envisaged that the proposed controller can be very useful for TMM driven applications as it is model independent, has fast response, high tracking accuracy, and minimal complexity.

Shape Recognition of a Tensegrity With Soft Sensor Threads and Artificial Muscles Using a Recurrent Neural Network

This letter proposes a novel method to accomplish shape recognition by utilizing a tensegrity structure with a soft sensor via a recurrent neural network (RNN). The combination of soft tensegrity and soft sensors make it capable of recognizing the deformation to reflect the shape of its surroundings. As the first step to this goal, we build a three-bar tensegrity prism with nine separate soft sensors in which the resistance value of the sensors changes with length variation. The prism is actuated by thin McKibben muscles and deforms when the pressure inside a muscle. The positions of the six nodes in the prism are obtained using a motion-capture system. The measured resistance and position data are used as training data for the RNN to build a prediction model that can reflect the shape variation during the period of deformation of the tensegrity. If several prisms are connected, they can be used with this approach to recognize the shape of a three-dimensional environment that is difficult to observe directly.

Flexible Pneumatic Bending Actuator for a Robotic Tongue

There are not many physical models of oral and laryngeal systems for human speech movement in both computer simulators and mechanical simulators. In particular, there is no robot tongue mechanism that completely reproduces the deformation motion of the human tongue. The human tongue is an aggregate of muscles devoid of a skeleton. It only possesses a small hyoid. The purpose of this study is to develop a flexible actuator without a rigid link, aiming at the development of a tongue mechanism for a mechanical speech robot. We propose a flexible pneumatic bending actuator using thin McKibben muscles and a soft body formed by a silicone resin. We have verified its mechanical characteristics and described a control method for displacement and curvature. The elasticity/compliance of the silicone resin forming the soft body of this actuator was quantified by tensile tests. The oscillation parameters were identified, and it is suggested that the dynamic model can be described by a spring-mass-damper system. Assuming an arc-shaped deformation model, a simultaneous control system for the arc length and curvature was constructed and its effectiveness was confirmed.

Segmentation of a Soft Body and its Bending Performance using Thin McKibben Muscle

In recent years, soft actuator has been extensively developed in robotic research. This type of robot is expected to work with human with its flexible and adaptable advantage. The actuator material is soft, light, safe and high compliant. Due to these factors, soft McKibben is of interest as an actuator for this research for bending application. This paper introduces a variant bending analysis of a soft body manipulated using soft McKibben actuators. A series of 1.80 mm width with the length of 120.0 mm McKibben actuator is used to control the bending motion. The design consists of four McKibben actuators arranged in parallel and compacted in a soft body. The bending behavior was evaluated using an experimental test with a variety of pneumatic input pressure and length section on the actuator. The experiment showed that the bending angle was influenced by the segmentation length of the actuator, where the segmentation length and increased input pressure also allow more bending on the actuator. The actuator with lot of section gave more bending response compared to the actuator with lesser section. With the performance exhibited from this study, McKibben actuator can be applied in a wider use for continuum manipulator.

A Compact McKibben Muscle Based Bending Actuator for Close-to-Body Application in Assistive Wearable Robots

In this letter we demonstrate a pneumatic bending actuator for upper-limb assistive wearable robots which uses thin McKibben muscles in combination with a flexure strip. The actuator features both active soft actuation and passive gravity support, and in terms of force transmission bridges the gap between the classic rigid type actuators and the emerging soft actuator technologies. Its flexure strip leverages the high-force low-displacement properties of McKibben muscles towards a large rotational range of motion and reduces localized forces at the attachments. We explain the synthesis method by which these actuators can be obtained and optimized for high specific moment output. Physical specimens of three optimized actuator designs are built and tested on a dedicated experimental setup, verifying the computational models. Furthermore, a proof-of-concept upper-limb assistive wearable robot is presented to illustrate a practical application of this actuator and its potential for close-to-body alignment. We found that based on our currently available components actuators can be built which, given a width of 80 mm, are able to produce a moment exceeding 4 Nm at an arm elevation of 90 deg.

A Wearable Multi Direction Ankle Exercise Device for DVT Prevention Using Thin McKibben Muscles

A Wearable Multi Direction Ankle Exercise Device for DVT Prevention Using Thin McKibben Muscles

Prototype of Fitting Mechanism for Assist suits with Thin Mckibben Muscles

Prototype of Fitting Mechanism for Assist suits with Thin Mckibben Muscles

Modeling and Measurement of Extension Torque of Rehabilitation Gloves Using Thin McKibben Muscles

Modeling and Measurement of Extension Torque of Rehabilitation Gloves Using Thin McKibben Muscles

Recurrent Braiding of Thin McKibben Muscles to Overcome Their Limitation of Contraction.

This study presents a novel idea of rebraiding thin McKibben muscles to overcome their limitation of contraction. The thin McKibben muscles, presented in the authors' previous work, have the flexibility that allows them to be braided. According to the experimental results of our previous research, the original single muscles have a contracting ratio of 28%, and the corresponding value for the muscles braided once is 37%. In this research, we achieved 41% contraction of thin McKibben muscles by braiding twice. The contraction ratio increases if the muscles are braided more. They will then overcome their limitation of contraction. In this report, several prototypes of muscles with different braiding times are designed, fabricated, modeled, and tested. As a result, the increase in the contraction ratio was confirmed from both a theoretical and an experimental point of view; the results were promising. We believe that recurrent-braided thin McKibben muscles will considerably help improve and develop various soft robotic applications in cases where a high contraction ratio is required.

Fabrication of “18 Weave” Muscles and Their Application to Soft Power Support Suit for Upper Limbs Using Thin McKibben Muscle

In this letter, we propose a novel active weave named “18 Weave” using a thin McKibben muscle and report on the application to a prototype soft power support suit for the upper limb. The active weave utilizes the flexibility of the thin McKibben muscle, which is used for warps and wefts. From the proposed structure, we confirmed that a 19.4% additional displacement is achieved compared to a single artificial muscle. The flexible and lightweight assistance suit can be realized with the active weave that has advantages of flexibility and shape adaptability. We confirmed the compliance and fatigue alleviation effect of the suit. Measurements of the myopotentials confirmed significant decreases in the activities of the anterior deltoid, posterior deltoid, biceps brachii, and triceps brachii muscles in their integrated electromyogram (iEMG).

Active Textile Braided in Three Strands with Thin McKibben Muscle.

This article presents an active textile braided in three strands with thin McKibben muscle. The fabrication of a textile using thin McKibben muscle as thread can be accomplished using a unique braiding method, developed in this study, to provide an active textile that shrinks along the transverse surface direction. This textile-type actuator is suitable as a type of soft robotic actuator for application in wearable robots and musculoskeletal robots because it is extremely lightweight, flexible, and easily applied to robot structures. In this article, the design and characteristics of a braided muscle in three strands, acting as the basic component of an active textile, as well as the design and static characteristics of the active textile, are presented. In addition, theoretical models are proposed for the active textile, and their theoretical characteristics are accordingly derived. The static characteristics of active textiles woven using various design parameters were then evaluated through experiments and modeling. The active textiles were found, both theoretically and experimentally, to provide a greater contraction ratio than a single muscle strand.

Prototype of Hand Rehabilitation Glove with Thin McKibben Muscles

Prototype of Hand Rehabilitation Glove with Thin McKibben Muscles

Recurrent Braiding of Thin McKibben Muscles to Improve Their Contracting Abilities

Recurrent Braiding of Thin McKibben Muscles to Improve Their Contracting Abilities

Braiding Thin McKibben Muscles to Enhance Their Contracting Abilities

This letter presents a novel concept of braiding thin McKibben muscles to improve their contracting ability compared to original muscles. Whereas a single original muscle and the conventional bundled muscle had a contracting ratio of 28%, braiding the muscles realized a contracting ratio of 37%. We designed, fabricated, and tested several prototypes with different braiding parameters, and demonstrated their effects both theoretically and experimentally. The results were promising and we believe that thin braided McKibben muscles will facilitate the development of novel musculoskeletal robots and be useful in various applications requiring soft robotic abilities.

Attempt of Barrier-Free Fashion by “Moving Clothes” with Thin Mckibben Muscle

Attempt of Barrier-Free Fashion by “Moving Clothes” with Thin Mckibben Muscle

Design of thin McKibben muscle and multifilament structure

Current McKibben muscles are usually 10–40mm in diameter, which makes them very stiff during contraction and difficult to deform rendering them unsuitable for dense mounting with shape adaptability in small spaces. In this research, to solve these problems, our group has developed the thinnest McKibben muscle reported until now. Bundling the muscles results in a multifilament muscle of the desired shape and flexibility. This paper reports the design of the thin McKibben muscle and the multifilament muscle and their static characteristics. In addition, we propose two theoretical models of multifilament muscles and derive their theoretical characteristics. The static characteristics of multifilament muscles with various design parameters have been evaluated through experiments and modeling. As a result, the greater contraction ratio of the multifilament muscles compared to that of the single muscle was demonstrated both theoretically and experimentally.