A Water-Hydraulic Upper-Limb Assistive Exoskeleton System with Displacement Estimation

This paper describes the development of an angle-sensorless exoskeleton with a tap water-driven artificial muscle actuator. The artificial muscle actuator consisted of an elastic rubber tube reinforced by braided fiber. Such actuators are highly flexible, lightweight, and water-resistant, and thus are inherently safe even for operations in direct contact with humans. An estimation system for the displacement of the artificial muscle actuator based on the water flow rates detected by flowmeters was constructed for the water-hydraulic exoskeleton. In addition, estimators of the velocity and acceleration of the actuator based on the estimated displacement and the measured flow rates were derived and incorporated into the estimation system. With this system, our previous wearable upper-limb assistive exoskeleton prototype was converted into an angle-sensorless version with higher safety in wet conditions. Its assistive performance was evaluated through experiments with research participants. Experimental results demonstrated that muscle activity could be reduced, although an assistive control strategy was executed with the variables estimated, excluding force.

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A modified physical model of high-strength water hydraulic artificial muscles considering the effects of geometry and material properties

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406221999077 ◽

2021 ◽

pp. 095440622199907

Author(s):

Zengmeng Zhang ◽

Jinkai Che ◽

Peipei Liu ◽

Yunrui Jia ◽

Yongjun Gong

Keyword(s):

Physical Model ◽

Relative Error ◽

Wall Thickness ◽

Material Properties ◽

High Strength ◽

Artificial Muscles ◽

Operating Pressure ◽

Rubber Tube ◽

Contraction Ratio ◽

Water Hydraulic

Compared with pneumatic artificial muscles (PAMs), water hydraulic artificial muscles (WHAMs) have the advantages of high force/weight ratio, high stiffness, rapid response speed, large operating pressure range, low working noise, etc. Although the physical models of PAMs have been widely studied, the model of WHAMs still need to be researched for the different structure parameters and work conditions between PAMs and WHAMs. Therefore, the geometry and the material properties need to be considered in models, including the wall thickness of rubber tube, the geometry of ends, the elastic force of rubber tube, the elongation of fibers, and the friction among fiber strands. WHAMs with different wall thickness and fiber materials were manufactured, and static characteristic experiments were performed when the actuator is static and fixed on both ends, which reflects the relationship between contraction force and pressure under the different contraction ratio. The deviations between theoretical values and experimental results were analyzed to investigate the effect of each physical factor on the modified physical model accuracy at different operating pressures. The results show the relative error of the modified physical model was 7.1% and the relative error of the ideal model was 17.4%. When contraction ratio is below 10% and operating pressure is 4 MPa, the wall thickness of rubber tube was the strongest factor on the accuracy of modified model. When the WHAM contraction ratio from 3% to 20%, the relative error between the modified physical model and the experimental data was within ±10%. Considering the various physical factors, the accuracy of the modified physical model of WHAM is improved, which lays a foundation of non-linear control of the high-strength, tightly fiber-braided and thick-walled WHAMs.

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The Gas Permeability of Plasma Sprayed Ceramic Coatings

Thermal Spray 1997: Proceedings from the United Thermal Spray Conference ◽

10.31399/asm.cp.itsc1997p0483 ◽

1997 ◽

Author(s):

A.C. Fox ◽

T.W. Clyne

Keyword(s):

Gas Permeability ◽

Test Procedure ◽

Ceramic Coatings ◽

Hydrogen Gas ◽

Steady State Flow ◽

Flow Rates ◽

Specific Permeability ◽

Measured Flow ◽

Flow Through ◽

Plasma Sprayed

Abstract A simple test procedure, based on steady state flow through a membrane, has been developed for measurement of the gas permeability of specimens over a range of temperature. The reliability of this equipment has been verified by testing solid disks containing single perforations and comparing the measured flow rates with those expected on the basis of laminar flow. Coatings of yttria-stabilised zirconia have been produced by plasma spraying in vacuum and in air. The specific permeability of these coatings has been measured at temperatures ranging up to 600°C, using hydrogen gas. It has been found that permeability is increased for coatings produced with longer stand-off distances and at higher pressures. Porosity levels have been measured using densitometry and microstructural features have been examined using SEM. A model has been developed for prediction of the permeability from such microstructural features, based on percolation theory. Agreement between predicted and measured permeabilities is good, although it is clear that more comprehensive data are needed in order to validate the model systematically.

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Flow Control by Pulso Width Modulation

Measurement and Control ◽

10.1177/002029407200500402 ◽

1972 ◽

Vol 5 (4) ◽

pp. 142-146

Author(s):

M S Beck ◽

N E Gough ◽

J N Smithies

Keyword(s):

Cross Correlation ◽

Pulse Width Modulation ◽

Correlation Method ◽

Temperature Fluctuations ◽

Flow Rates ◽

Start Up ◽

On Line ◽

Measured Flow ◽

Novel Method ◽

Modulation Control

A novel method of controlling the flow rates of fluids has been devised which is particularly suitable for highly erosive fluids and slurries. The width of pulses in a pulse train actuating an on-off valve is modulated according to the error between the desired and measured flow rates and thus the ratio of the total times the valve spends in its ‘on’ and ‘off’ states is varied. The method has been tested with an on-line computer which was used to measure the flow rate of water by a cross-correlation method to determine the transit time of temperature fluctuations between two thermocouples in the pipe, and to implement the pulse width modulation control. Satisfactory results have been obtained for start-up, set-point changes and load disturbances for flow rates in the turbulent region (Re > 3 600). Future development includes the use of a fluidic diverter as the on-off device.

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Development of Wearable Master-slave Upper Limb Training Device Using Pneumatic Artificial Muscle

Transactions of the Society of Instrument and Control Engineers ◽

10.9746/sicetr.49.166 ◽

2013 ◽

Vol 49 (1) ◽

pp. 166-175 ◽

Cited By ~ 1

Author(s):

Daisuke SASAKI ◽

Toshiro NORITSUGU ◽

Masahiro TAKAIWA

Keyword(s):

Upper Limb ◽

Artificial Muscle ◽

Pneumatic Artificial Muscle ◽

Training Device

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Versatile water hydraulic motor driven by tap water

Proceedings. 2000 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2000) (Cat. No.00CH37113) ◽

10.1109/iros.2000.895256 ◽

2002 ◽

Cited By ~ 3

Author(s):

H. Tsukagoshi ◽

S. Nozaki ◽

A. Kitagawa

Keyword(s):

Tap Water ◽

Hydraulic Motor ◽

Water Hydraulic

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Analysis and Simulation on Drive Characteristic of High-Strength Water Hydraulic Artificial Muscle

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.889-890.488 ◽

2014 ◽

Vol 889-890 ◽

pp. 488-492

Author(s):

Zeng Meng Zhang ◽

Jiao Yi Hou ◽

Zheng Wen Sun ◽

Yong Jun Gong ◽

Jian Miao

Keyword(s):

Flow Rate ◽

Control Valve ◽

Artificial Muscle ◽

High Strength ◽

Hydraulic Control ◽

Hydraulic Circuit ◽

Water Hydraulic ◽

The Difference ◽

Hydraulic Valves ◽

Load Mass

Driving processes and characteristics are different between the water hydraulic artificial muscle and pneumatic artificial muscle due to the difference of work media employed in muscles. An appropriative hydraulic circuit was designed to control the pressure of the water hydraulic artificial muscle and the performance of this system was analyzed. An AMESim model of the control system was built and the dynamic characteristics are analyzed with various parameters of the hydraulic circuit and various loads by simulation. The results show that the performance of the water hydraulic control valve should agree with the dimension of the water hydraulic artificial muscle. The rated flow rate of the water hydraulic valves can be selected increasingly while the load mass is low. Meanwhile, the overshoot is generated and enlarged along with the increases of the flow rate and load mass. These contribute to the improvements of designs and researches on control systems of water hydraulic artificial muscles.

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Effect of Activating Device on the Properties of Tap Water

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.178.86 ◽

2010 ◽

Vol 178 ◽

pp. 86-91 ◽

Cited By ~ 3

Author(s):

Dong Mei Zhang ◽

Jin Sheng Liang ◽

Yan Ding ◽

Can Li

Keyword(s):

Surface Tension ◽

Water Clusters ◽

Ph Value ◽

Tap Water ◽

Far Infrared ◽

Zinc Alloy ◽

17O Nmr ◽

Flow Rates ◽

Copper Zinc ◽

Functional Ceramic

Effect of activating device on the property of tap water was studied by surface tensiometer and pH meter. The results showed that the surface tension of tap water activated by the device reduced and pH value increased. The variations of surface tension and pH value are connected with flow rates. The larger flow rate, the less variation of surface tension and pH value when at the same cycle time, however, the more variation of surface tension and pH value when at the same activating time. Activated by the device, 17O NMR half width of tap water reduced from 70.79Hz at the inlet to 60.87Hz at the outlet. Reduction of surface tension were caused by hydrogen bonds in water clusters which were weakened or broken by far-infrared radiation of functional ceramic ball and galvanic cell action of copper-zinc alloy. Increment of pH value were caused by H+ in water exchanging with metal cations on surface of far-infrared ceramic balls and dissolved oxygen getting electron and forming OH-1 with the function of copper-zinc alloy.

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A Device for Measuring Thin Fluid Flow Depth Over an Inclined Open Rectangular Channel

Journal of Fluids Engineering ◽

10.1115/1.3153362 ◽

2009 ◽

Vol 131 (10) ◽

Cited By ~ 3

Author(s):

A. K. Majumder

Keyword(s):

Fluid Flow ◽

Flow Behavior ◽

Rectangular Channel ◽

Flow Characteristics ◽

Operating Conditions ◽

Multiple Point ◽

Flow Depth ◽

Flow Rates ◽

Law Of The Wall ◽

Measured Flow

Accurate knowledge of the fluid flow depth over an inclined rectangular open channel is of obvious value in the modeling of flow characteristics over that channel. Understanding of this type of fluid flow behavior is of immense importance to the mineral processing fraternity as a large number of separators work on this principle. Therefore, a multiple point computer-controlled depth gauge was developed to measure water flow depths at various flow rates ranging from 0.81 l/s to 2.26 l/s over an inclined (17.5 deg) rectangular channel (2400 mm long and 370 mm wide). This paper describes the details about the device and the data acquisition procedure. An attempt has also been made to predict the measured flow depths at various operating conditions by using a modified form of the conventional law of the wall model. An overall relative error of 4.23% between the measured and the predicted flow depths at various flow rates establishes the validity of the model.

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Posture Control Considering Joint Stiffness of a Robotic Arm Driven by Rubberless Artificial Muscle

International Journal of Automation Technology ◽

10.20965/ijat.2016.p0503 ◽

2016 ◽

Vol 10 (4) ◽

pp. 503-510 ◽

Cited By ~ 1

Author(s):

Naoki Saito ◽

◽

Toshiyuki Satoh ◽

Keyword(s):

Joint Angle ◽

Joint Stiffness ◽

Mathematical Expression ◽

Artificial Muscle ◽

Good Control ◽

Robotic Arm ◽

Rubber Tube ◽

Robotic Arms ◽

Control Scheme ◽

The Relationship

This paper describes a joint angle control considering the passive joint stiffness of robotic arms driven by rubberless artificial muscle (RLAM), which is a pneumatic actuator. The contraction mechanism of RLAM is the same as that of the McKibben artificial muscle. Unlike the McKibben artificial muscle, RLAM is constructed using an airbag made of a nonelastic material instead of a rubber tube.The objective of this study is to realize a soft contact movement of robotic arms by applying the passive compliance characteristics of RLAMs. In this study, we derive a mathematical expression for the relationship between the output of an RLAM and the joint stiffness of a robotic arm. In addition, we suggest a control scheme for each RLAM. We confirm the validity of these suggestions experimentally. From the result, we observe a good control performance of the joint angle. A robotic arm moves smoothly according to the force added from outside by setting the passive stiffness of the arm.

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