A Study on Anthropomorphic Robot Hand Simulation Driven by SMA Wire Using Segment Control

2007 ◽  
Vol 345-346 ◽  
pp. 1249-1252 ◽  
Author(s):  
Kyoung Rae Cha ◽  
Gwang Ho Kim ◽  
Ju Hwan Kim ◽  
Sang Hwa Jeong
Keyword(s):  
Energy Density ◽  
Dynamic Characteristics ◽  
Weight Ratio ◽  
Artificial Muscle ◽  
Robotic Systems ◽  
Robotic Hand ◽  
Electromechanical Actuators ◽  
New Approach ◽  
And Control ◽  
Thermal States

In recent years, as the robot technology is developed, the researches on the artificial muscle actuator that enables robot to move dexterously like biological organ become active. Actuators are one of the key technologies underpinning robotics. Particularly breakthroughs of power-to-weight ratio or energy-density in actuator technology have significant impacts upon the design and the control of robotic systems. The widely used materials for artificial muscle are the shape memory alloy and electro-active polymer. These actuators have the higher energy density than the electromechanical actuators such as the electric motor. However, there are some drawbacks because these actuators have the hysteretic dynamic characteristics. In this paper, the segment control for reducing the hysteresis of SMA is proposed and the simulation of an anthropomorphic robotic hand is performed using ADAMS. A new approach to design and control of SMA actuators is presented. SMA wire is divided into many segments and their thermal states are controlled individually in a binary manner(ON/OFF). The basic experiment for evaluating the dynamic characteristics of SMA wire actuator is performed.

scholarly journals CONTROL NOVEL MODEL OF KNEE CPM DEVICE

2009 ◽  
Vol 12 (4) ◽  
pp. 18-29
Author(s):  
Thanh Diep Cong Tu
Keyword(s):  
Weight Ratio ◽  
Artificial Muscle ◽  
Network Control ◽  
Continuous Passive Motion ◽  
The Novel ◽  
Highly Nonlinear ◽  
Cord Injury ◽  
And Control ◽  
Novel Model ◽  
Interesting Alternative

In recent years, CPM - Continuous Passive Motion has been proved to be one of the most effective therapeutic methods for patients who have problems with motion such as spinal cord injury, ankle and knee injury, parkinson and so on. Many commercial CPM devices are found in market but all of them use motors as the main actuators. The lack of human compliance of electric actuators, which are commonly used in these machines, makes them potentially harmful to patients. An interesting alternative, to electric actuators for medical purposes, particularly promising for rehabilitation, is a pneumatic artificial muscle (PAM) actuator because of its high power/weight ratio and compliance properties. However, the highly nonlinear and hysteresis of PAM make it the challenging for design and control. In this study, a PID compensation using neural network control is studied to improve the control performance of the novel model of Knee CPM device.

Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part One—Design Process

2011 ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Tad Driver ◽  
Xiangrong Shen
Keyword(s):  
Controller Design ◽  
Artificial Muscle ◽  
The Other ◽  
Robotic Systems ◽  
Pneumatic Artificial Muscle ◽  
Actuation System ◽  
Torque Curve ◽  
System Part ◽  
New Feature ◽  
And Control

This paper describes the design and control of a compact and flexible pneumatic artificial muscle (PAM) actuation system for bio-robotic systems. The entire paper is divided into two parts, with the first part covering the mechanism design and the second part covering the corresponding controller design. This novel system presented in this part incorporates two new features, including a variable-radius pulley based PAM actuation mechanism, and a spring-return mechanism to replace the PAM in the “weak” direction. With the pulley radius as a function of the joint angle, this new feature enables the designer to freely modulate the shape of the torque curve, and thus achieves a significantly higher flexibility than the traditional configuration. The other new feature, the spring-return mechanism, is inspired by the fact that a large number of bio-robotic systems require a significantly larger torque in one direction than the other.

Motor unit buckling in variable recruitment fluidic artificial muscle bundles: implications and mitigations

2022 ◽  
Author(s):  
Nicholas Mazzoleni ◽  
Jeong Yong Kim ◽  
Matthew Bryant
Keyword(s):  
Energy Density ◽  
Weight Ratio ◽  
Artificial Muscle ◽  
Motor Units ◽  
Mitigation Strategy ◽  
Force Output ◽  
Operational Life ◽  
Resistive Forces ◽  
Variable Recruitment ◽  
Fixed End

Abstract Fluidic artificial muscles (FAMs) are a popular actuation choice due to their compliant nature and high force-to-weight ratio. Variable recruitment is a bio-inspired actuation strategy in which multiple FAMs are combined into motor units that can be pressurized sequentially according to load demand. In a traditional ‘fixed-end’ variable recruitment FAM bundle, inactive units and activated units that are past free strain will compress and buckle outward, resulting in resistive forces that reduce overall bundle force output, increase spatial envelope, and reduce operational life. This paper investigates the use of inextensible tendons as a mitigation strategy for preventing resistive forces and outward buckling of inactive and submaximally activated motor units in a variable recruitment FAM bundle. A traditional analytical fixed-end variable recruitment FAM bundle model is modified to account for tendons, and the force-strain spaces of the two configurations are compared while keeping the overall bundle length constant. Actuation efficiency for the two configurations is compared for two different cases: one case in which the radii of all FAMs within the bundle are equivalent, and one case in which the bundles are sized to consume the same amount of working fluidvolume at maximum contraction. Efficiency benefits can be found for either configuration for different locations within their shared force-strain space, so depending on the loading requirements, one configuration may be more efficient than the other. Additionally, a study is performed to quantify the increase in spatial envelope caused by the outward buckling of inactive or low-pressure motor units. It was found that at full activation of recruitment states 1, 2, and 3, the tendoned configuration has a significantly higher volumetric energy density than the fixed-end configuration, indicating that the tendoned configuration has more actuation potential for a given spatial envelope. Overall, the results show that using a resistive force mitigation strategy such as tendons can completely eliminate resistive forces, increase volumetric energy density, and increase system efficiency for certain loading cases. Thus, there is a compelling case to be made for the use of tendoned FAMs in variable recruitment bundles.

Experimental Characterization and Control of Miniaturized Pneumatic Artificial Muscle

2014 ◽  
Vol 8 (4) ◽  
Author(s):  
Shanthanu Chakravarthy ◽  
K. Aditya ◽  
Ashitava Ghosal
Keyword(s):  
Experimental Data ◽  
Applied Pressure ◽  
Weight Ratio ◽  
Artificial Muscle ◽  
Good Choice ◽  
Outer Diameter ◽  
Pneumatic Muscle ◽  
Surgical Tools ◽  
Contraction Ratio ◽  
And Control

Robotic surgical tools used in minimally invasive surgeries (MIS) require miniaturized and reliable actuators for precise positioning and control of the end-effector. Miniature pneumatic artificial muscles (MPAMs) are a good choice due to their inert nature, high force to weight ratio, and fast actuation. In this paper, we present the development of miniaturized braided pneumatic muscles with an outer diameter of ∼1.2 mm, a high contraction ratio of about 18%, and capable of providing a pull force in excess of 4 N at a supply pressure of 0.8 MPa. We present the details of the developed experimental setup, experimental data on contraction and force as a function of applied pressure, and characterization of the MPAM. We also present a simple kinematics and experimental data based model of the braided pneumatic muscle and show that the model predicts contraction in length to within 20% of the measured value. Finally, a robust controller for the MPAMs is developed and validated with experiments and it is shown that the MPAMs have a time constant of ∼10 ms thereby making them suitable for actuating endoscopic and robotic surgical tools.

On-Surface Radical Oligomerisation: A New Approach to STM Tip-Induced Reactions

2018 ◽  
Author(s):  
Gaolei Zhan ◽  
Younes Makoudi ◽  
Judicael Jeannoutot ◽  
Simon Lamare ◽  
Michel Féron ◽  
...  
Keyword(s):  
Sample Surface ◽  
Scanning Tunnelling Microscope ◽  
Transfer Event ◽  
New Approach ◽  
The Past ◽  
Organic Nanostructures ◽  
Scanning Tunnelling ◽  
New Strategy ◽  
Surface Fabrication ◽  
And Control

Over the past decade, on-surface fabrication of organic nanostructures has been widely investigated for the development of molecular electronic devices, nanomachines, and new materials. Here, we introduce a new strategy to obtain alkyl oligomers in a controlled manner using on-surface radical oligomerisations that are triggered by the electrons/holes between the sample surface and the tip of a scanning tunnelling microscope. The resulting radical-mediated mechanism is substantiated by a detailed theoretical study. This electron transfer event only occurs when <i>V</i><sub>s</sub> < -3 V or <i>V</i><sub>s</sub> > + 3 V and allows access to reactive radical species under exceptionally mild conditions. This transfer can effectively ‘switch on’ a sequence leading to formation of oligomers of defined size distribution due to the on-surface confinement of reactive species. Our approach enables new ways to initiate and control radical oligomerisations with tunnelling electrons, leading to molecularly precise nanofabrication.

Electrostatic bellow muscle actuators and energy harvesters that stack up

2021 ◽  
Vol 6 (51) ◽  
pp. eaaz5796
Author(s):  
I. D. Sîrbu ◽  
G. Moretti ◽  
G. Bortolotti ◽  
M. Bolignari ◽  
S. Diré ◽  
...  
Keyword(s):  
High Performance ◽  
High Reliability ◽  
Low Cost ◽  
Artificial Muscle ◽  
Pressure Head ◽  
Robotic Systems ◽  
Maximum Pressure ◽  
Term Operation ◽  
Energy Harvesters ◽  
Out Of Plane

Future robotic systems will be pervasive technologies operating autonomously in unknown spaces that are shared with humans. Such complex interactions make it compulsory for them to be lightweight, soft, and efficient in a way to guarantee safety, robustness, and long-term operation. Such a set of qualities can be achieved using soft multipurpose systems that combine, integrate, and commute between conventional electromechanical and fluidic drives, as well as harvest energy during inactive actuation phases for increased energy efficiency. Here, we present an electrostatic actuator made of thin films and liquid dielectrics combined with rigid polymeric stiffening elements to form a circular electrostatic bellow muscle (EBM) unit capable of out-of-plane contraction. These units are easy to manufacture and can be arranged in arrays and stacks, which can be used as a contractile artificial muscle, as a pump for fluid-driven soft robots, or as an energy harvester. As an artificial muscle, EBMs of 20 to 40 millimeters in diameter can exert forces of up to 6 newtons, lift loads over a hundred times their own weight, and reach contractions of over 40% with strain rates over 1200% per second, with a bandwidth over 10 hertz. As a pump driver, these EBMs produce flow rates of up to 0.63 liters per minute and maximum pressure head of 6 kilopascals, whereas as generator, they reach a conversion efficiency close to 20%. The compact shape, low cost, simple assembling procedure, high reliability, and large contractions make the EBM a promising technology for high-performance robotic systems.

Considerations on Designing Artificial Muscle Working at High Pressure

2012 ◽  
Vol 268-270 ◽  
pp. 1457-1463
Author(s):  
Li Chao Wang ◽  
Xiao Dong Wang
Keyword(s):  
High Pressure ◽  
Material Properties ◽  
Weight Ratio ◽  
Artificial Muscle ◽  
Force Output ◽  
Compact Structure ◽  
Small Power ◽  
Small Force ◽  
Working Principle ◽  
Contraction Angle

Artificial muscle is a new style of actuator with novel working principle, which owns the advantages of compact structure, high power-to-weight ratio, compliance and easy application. Pneumatic artificial muscle (PAM) is usually used in robotics, medical auxiliaries and other small force output occasions nowadays. However, it suffers problems of small power, hysteresis and poor repeatability. A kind of artificial muscle working at high pressure was researched. Different muscle styles are compared and MicKibben structure is selected while fluid media is determined. Furthermore, factors of geometry and material properties, which limit the ultimate pressure, are analyzed. Formulas and simulations verify the influence of limitation and help to calculate key parameters of 18MPa artificial muscle. Data show that it is possible in theory to design high pressure artificial muscle by overall consideration of initial diameter, initial contraction angle and material properties, initial length only influent the stroke.

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