Experimentally identified models of McKibben soft actuators as primary movers and passive structures

2021 ◽  
pp. 1-37
Author(s):  
Gina Olson ◽  
Holly Manjarrez ◽  
Julie Adams ◽  
Yigit Menguc
Keyword(s):  
Empirical Relationships ◽  
Soft Robots ◽  
Trade Off ◽  
Future Design ◽  
Design Variation ◽  
Complete Set ◽  
Mckibben Actuators ◽  
Soft Actuators ◽  
Force Displacement ◽  
Actuation Strain

Abstract Soft robots join body and actuation, forming their structure from the same elements that induce motion. Soft actuators are commonly modeled or characterized as primary movers, but their second role as support structure introduces strain-pressure combinations outside of normal actuation. This manuscript examines a more complete set of possible strain-pressure combinations for McKibben actuators, including passive, or unpressurized, deformation, pressurized extension and compression of a pressurized actuator beyond the maximum actuation strain. Each region is investigated experimentally, and empirical force-displacement-pressure relationships are identified. Particular focus is placed on ensuring empirical relationships are consistent at boundaries between an actuator's strain-pressure regions. The presented methodology is applied to seven McKibben actuator designs, which span variations in wall thickness, enclosure material and actuator diameter. Empirical results demonstrate a trade-off between maximum contraction strain and force required to passively extend. The results also show that stiffer elastomers require an extreme increase in pressure to contract without a compensatory increase in maximum achieved force. Empirical force-displacement-pressure models were developed for each variant across all the studied strain-pressure regions, enabling future design variation studies for soft robots that use actuators as structures.

scholarly journals Dragonfly Inspired Smart Soft Robot

2020 ◽  
Author(s):  
Vardhman Kumar ◽  
Ung Hyun Ko ◽  
Yilong Zhou ◽  
Jiaul Hoque ◽  
Gaurav Arya ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Stimuli Responsive ◽  
Complex Environments ◽  
Soft Robots ◽  
Responsive Materials ◽  
Environmental Perturbations ◽  
Integration Strategies ◽  
Soft Actuators ◽  
Harsh Conditions

Recent advancements in soft robotics have led to the development of compliant robots that can exhibit complex motions driven by living cells(1, 2), chemical reactions(3), or electronics(4). Further innovations are however needed to create the next generation of soft robots that can carry out advanced functions beyond locomotion. Here we describe DraBot—a dragonfly-inspired, entirely soft, multifunctional robot that combines long-term locomotion over water surface with sensing, responding, and adaptation capabilities. By integrating soft actuators, stimuli-responsive materials, and microarchitectural features, we created a circuitry of pneumatic and microfluidic logic that enabled the robot to undergo user- and environment-controlled (pH) locomotion, including navigating hazardous (acidic) conditions. DraBot was also engineered to sense additional environmental perturbations (temperature) and detect and clean up chemicals (oil). The design, fabrication, and integration strategies demonstrated here pave a way for developing futuristic soft robots that can acclimatize and adapt to harsh conditions while carrying out complex tasks such as exploration, environmental remediation, and health care in complex environments.

Precharged Pneumatic Soft Actuators and Their Applications to Untethered Soft Robots

Soft Robotics ◽  
2018 ◽  
Vol 5 (5) ◽  
pp. 567-575 ◽  
Author(s):  
Yunquan Li ◽  
Yonghua Chen ◽  
Tao Ren ◽  
Yingtian Li ◽  
Shiu hong Choi
Keyword(s):  
Soft Robots ◽  
Soft Actuators

Thermally Driven Mechanical Actuators by Using Absorption/Desorption of Metal Hydrides: A Comprehensive Simulation

2004 ◽  
Author(s):  
George M. Lloyd ◽  
Kwang J. Kim ◽  
K. Xia ◽  
A. Razani ◽  
M. Shahinpoor
Keyword(s):  
Power Efficiency ◽  
Metal Hydrides ◽  
Input Power ◽  
Performance Bounds ◽  
Pneumatic Actuators ◽  
Advantages And Disadvantages ◽  
Simulation Strategy ◽  
Thermally Driven ◽  
Mckibben Actuators ◽  
Force Displacement

Metal hydrides have been investigated for use in a number of applications, such as heat regenerators, thermal compressors, and hydrogen storage. McKibben actuators are pneumatic actuators that have unique characteristics, such as biomimeticity (having force/deflection characteristics similar to natural muscles), compactness, high force-to-mass ratios, and moreover are lubricationless, noiseless, soft actuating, and environmentally benign. Actuators with these characteristics are ideal for many industrial, space, defense, robotic, and biomedical applications. The combination of metal hydride technology with McKibben actuators builds on the advantages of both technologies, while mitigating the deficiencies of each. In this paper, we report results from a comprehensive simulation strategy for a LaNi4.3Al0.7 based McKibben actuator. The simulations are able to predict and characterize the performance bounds of the actuator in terms of actuator time/thermal input, power/efficiency and force/displacement diagrams. The advantages and disadvantages of the design are discussed from these perspectives.

Realistic and Highly Functional Pediatric Externally Powered Prosthetic Hand Using Pneumatic Soft Actuators

2020 ◽  
Vol 32 (5) ◽  
pp. 1034-1043
Author(s):  
Hironari Taniguchi ◽  
Nobuo Takemoto ◽  
Ren Yakami ◽  
Shuichi Wakimoto ◽  
Takero Oshikawa ◽  
...  
Keyword(s):  
Body Image ◽  
Acrylonitrile Butadiene Styrene ◽  
Human Hand ◽  
Prosthetic Hand ◽  
Early Age ◽  
Flexible Joint ◽  
Human Arm ◽  
Mckibben Actuators ◽  
Soft Actuators ◽  
Butadiene Styrene

It is known that introducing a pediatric externally powered prosthetic hand from an early age has certain merits such as the recovery of body image. However, this process is not popular in Japan. The high cost and technological problems of the hand have resulted in difficulty in its popularization. The pediatric prosthetic hand must be lighter and smaller than the adult one. Furthermore, parents of users prefer a prosthetic hand, such as a human arm and hand. We developed a prosthetic hand that demonstrates certain functionalities and appearances similar to a real human hand. The prosthetic hand consists of miniature McKibben actuators and is manufactured from acrylonitrile-butadiene-styrene resin and covered by a silicon glove. It has flexible joint structures and can grasp objects of various shapes. In this paper, we present a prototype of the pediatric prosthetic hand and the results of gripping experiments, bending and extension of finger experiments, and user tests.

scholarly journals Review of machine learning methods in soft robotics

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246102
Author(s):  
Daekyum Kim ◽  
Sang-Hun Kim ◽  
Taekyoung Kim ◽  
Brian Byunghyun Kang ◽  
Minhyuk Lee ◽  
...  
Keyword(s):  
Machine Learning ◽  
Soft Materials ◽  
Research Field ◽  
Machine Learning Techniques ◽  
Learning Approaches ◽  
Learning Methods ◽  
Soft Robots ◽  
Machine Learning Methods ◽  
Wearable Robots ◽  
Soft Actuators

Soft robots have been extensively researched due to their flexible, deformable, and adaptive characteristics. However, compared to rigid robots, soft robots have issues in modeling, calibration, and control in that the innate characteristics of the soft materials can cause complex behaviors due to non-linearity and hysteresis. To overcome these limitations, recent studies have applied various approaches based on machine learning. This paper presents existing machine learning techniques in the soft robotic fields and categorizes the implementation of machine learning approaches in different soft robotic applications, which include soft sensors, soft actuators, and applications such as soft wearable robots. An analysis of the trends of different machine learning approaches with respect to different types of soft robot applications is presented; in addition to the current limitations in the research field, followed by a summary of the existing machine learning methods for soft robots.

Modeling, Analysis, and Function Extension of the McKibben Hydraulic Artificial Muscles

2020 ◽  
Author(s):  
Siqing Chen ◽  
He Xu
Keyword(s):  
High Pressure ◽  
Theoretical Analysis ◽  
Artificial Muscle ◽  
Design Parameters ◽  
Artificial Muscles ◽  
Soft Robots ◽  
The Law ◽  
Soft Actuators ◽  
The Impact ◽  
The Relationship

Abstract Compared with rigid robots, flexible robots have soft and extensible bodies enforcing their abilities to absorb shock and vibration, hence reducing the impact of probable collisions. Due to their high adaptability and minimally invasive features, soft robots are used in various fields. The McKibben hydraulic artificial muscles are the most popular soft actuator because of the controllability of hydraulic actuator and high force to weight ratio. When its deformation reaches a certain level, the actuators can be stopped automatically without any other braking mechanism. The research of McKibben hydraulic artificial muscles is beneficial to the theoretical analysis of soft actuators in the mechanical system. The design of soft actuators with different deformations promotes the development of soft robots. In this paper, a static modeling of the McKibben hydraulic artificial muscles is established, and its correctness is verified by theoretical analysis and experiment. In this model, the deformation mechanism of the artificial muscle and the law of output force is put forward. The relationship between muscle pressure, load, deformation, and muscle design parameters is presented through the mechanical analysis of the braid, elastic tube, and sealed-end. The law of the muscle deformation with high pressure is predicted. The reason for the muscle’s tiny elongation with extremely high pressure is found through the analysis of the relationship between the angle of the braid, the length of single braided thread, and the pressure. With the increase of pressure, the angle of the braid tends to a fixed value. As the stress of braided thread increases, so does its length. The length changes obviously when the stress is extremely enormous. The angle of the braid and the length of the braided thread control the deformation of artificial muscles, resulting in a slight lengthening with extreme high pressure. Under normal pressure, the length of the braided wire is negligible, so that the entire muscle becomes shorter. According to the modeling and theoretical analysis, a new McKibben hydraulic artificial muscle that can elongate under normal rising pressure is designed. This artificial muscle can grow longer with pressure increases, eventually reaching its maximum length. During this time, its diameter barely changes. Its access pressure is higher than that of conventional elongated artificial muscles. Through experiments, the relationship between the muscle deformation, pressure, and load still conform to this theoretical model. This model can be used for the control of soft actuators and the design of new soft robots. This extensional McKibben hydraulic artificial muscles and the conventional McKibben hydraulic artificial muscles can be used in the bilateral control of soft robots.

scholarly journals Contactless Manipulation of Soft Robots

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3065 ◽  
Author(s):  
Kim ◽  
Park ◽  
Won ◽  
Jeon ◽  
Wie
Keyword(s):  
Recent Progress ◽  
Polymeric Materials ◽  
Anisotropic Materials ◽  
Robotic Systems ◽  
Soft Robots ◽  
Mechanical Joints ◽  
Potential Applications ◽  
Soft Actuators ◽  
External Stimuli ◽  
The Given

In recent years, jointless soft robots have demonstrated various curvilinear motions unlike conventional robotic systems requiring complex mechanical joints and electrical design principles. The materials employed to construct soft robots are mainly programmable anisotropic polymeric materials to achieve contactless manipulation of miniaturized and lightweight soft robots through their anisotropic strain responsivity to external stimuli. Although reviews on soft actuators are extensive, those on untethered soft robots are scant. In this study, we focus on the recent progress in the manipulation of untethered soft robots upon receiving external stimuli such as magnetic fields, light, humidity, and organic solvents. For each external stimulus, we provide an overview of the working principles along with the characteristics of programmable anisotropic materials and polymeric composites used in soft robotic systems. In addition, potential applications for untethered soft robots are discussed based on the physicochemical properties of programmable anisotropic materials for the given external stimuli.

TRADE-OFF BETWEEN COMPUTATION TIME AND NUMBER OF RULES FOR FUZZY MINING FROM QUANTITATIVE DATA

2001 ◽  
Vol 09 (05) ◽  
pp. 587-604 ◽  
Author(s):  
TZUNG-PEI HONG ◽  
CHAN-SHENG KUO ◽  
SHENG-CHAI CHI
Keyword(s):  
Data Mining ◽  
Computation Time ◽  
Data Mining Algorithm ◽  
Trade Off ◽  
Fuzzy Association Rules ◽  
Data Mining Algorithms ◽  
Mining Algorithm ◽  
Linguistic Term ◽  
Complete Set ◽  
Mining Algorithms

Data mining is the process of extracting desirable knowledge or interesting patterns from existing databases for specific purposes. Most conventional data-mining algorithms identify the relationships among transactions using binary values. Transactions with quantitative values are however commonly seen in real-world applications. We proposed a fuzzy mining algorithm by which each attribute used only the linguistic term with the maximum cardinality int he mining process. The number of items was thus the same as that of the original attributes, making the processing time reduced. The fuzzy association rules derived in this way are not complete. This paper thus modifies it and proposes a new fuzzy data-mining algorithm for extrating interesting knowledge from transactions stored as quantitative values. The proposed algorithm can derive a more complete set of rules but with more computation time than the method proposed. Trade-off thus exists between the computation time and the completeness of rules. Choosing an appropriate learning method thus depends on the requirement of the application domains.

scholarly journals Underwater Crawling Robot With Hydraulic Soft Actuators

2021 ◽  
Vol 8 ◽  
Author(s):  
Qinlin Tan ◽  
Yishan Chen ◽  
Jianhui Liu ◽  
Kehan Zou ◽  
Juan Yi ◽  
...  
Keyword(s):  
Weight Ratio ◽  
Vital Role ◽  
Soft Robots ◽  
Actuation System ◽  
Structural Rigidity ◽  
Hybrid Mechanism ◽  
Peristaltic Pumps ◽  
Motion Range ◽  
Soft Actuators ◽  
Leg Design

Benthic operation plays a vital role in underwater applications, where crawling robots have advantages compared with turbine-based underwater vehicles, in locomotion accuracy, actuation efficiency, current resistance, and in carrying more payloads. On the other hand, soft robots are quickly trending in underwater robotic design, with their naturally sealed body structure and intrinsic compliance both desirable for the highly unstructured and corrosive underwater environment. However, the limitations resulting directly from the inherent compliance, in structural rigidity, actuation precision, and limited force exertion capability, have also restricted soft robots in underwater applications. To date soft robots are adopted mainly as grippers and manipulators for atraumatic sampling, rather than as locomotion platforms. In this work, we present a soft-robotic approach to designing underwater crawling robots, with three main innovations: 1) using rigid structural components to strategically reinforce the otherwise omni-directionally flexible soft actuators, drastically increasing their loading capability and actuation precision; 2) proposing a rigid–soft hybrid multi-joint leg design, with quasi-linear motion range and force exertion, while maintaining excellent passive impact compliance by exploiting the inherent flexibility of soft actuators; 3) developing a novel valve-free hydraulic actuation system with peristaltic pumps, achieving a compact, lightweight, and untethered underwater crawling robot prototype with a 5:1 payload-to-weight ratio and multi-gait capability. The prototype was tested for design verification and showcasing the advantages of the proposed hybrid mechanism and actuation approach.

scholarly journals One Soft Step: Bio-Inspired Artificial Muscle Mechanisms for Space Applications

2022 ◽  
Vol 8 ◽  
Author(s):  
Joseph Ashby ◽  
Samuel Rosset ◽  
E.-F. Markus Henke ◽  
Iain A. Anderson
Keyword(s):  
Outer Space ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Space Applications ◽  
Soft Robots ◽  
Deformable Bodies ◽  
Low Mass ◽  
Soft Actuators ◽  
The Cost ◽  
High Work

Soft robots, devices with deformable bodies and powered by soft actuators, may fill a hitherto unexplored niche in outer space. All space-bound payloads are heavily limited in terms of mass and volume, due to the cost of launch and the size of spacecraft. Being constructed from stretchable materials allows many possibilities for compacting soft robots for launch and later deploying into a much larger volume, through folding, rolling, and inflation. This morphability can also be beneficial for adapting to operation in different environments, providing versatility, and robustness. To be truly soft, a robot must be powered by soft actuators. Dielectric elastomer transducers (DETs) offer many advantages as artificial muscles. They are lightweight, have a high work density, and are capable of artificial proprioception. Taking inspiration from nature, in particular the starfish podia, we present here bio-inspired inflatable DET actuators powering low-mass robots capable of performing complex motion that can be compacted to a fraction of their operating size.

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