A Wearable Soft Fabric Sleeve for Upper Limb Augmentation

Soft actuators (SAs) have been used in many compliant robotic structure and wearable devices, due to their safe interaction with the wearers. Despite advances, the capability of current SAs is limited by scalability, high hysteresis, and slow responses. In this paper, a new class of soft, scalable, and high-aspect ratio fiber-reinforced hydraulic SAs is introduced. The new SA uses a simple fabrication process of insertion where a hollow elastic rubber tube is directly inserted into a constrained hollow coil, eliminating the need for the manual wrapping of an inextensible fiber around a long elastic structure. To provide high adaptation to the user skin for wearable applications, the new SAs are integrated into flexible fabrics to form a wearable fabric sleeve. To monitor the SA elongation, a soft liquid metal-based fabric piezoresistive sensor is also developed. To capture the nonlinear hysteresis of the SA, a novel asymmetric hysteresis model which only requires five model parameters in its structure is developed and experimentally validated. The new SAs-driven wearable robotic sleeve is scalable, highly flexible, and lightweight. It can also produce a large amount of force of around 23 N per muscle at around 30% elongation, to provide useful assistance to the human upper limbs. Experimental results show that the soft fabric sleeve can augment a user’s performance when working against a load, evidenced by a significant reduction on the muscular effort, as monitored by electromyogram (EMG) signals. The performance of the developed SAs, soft fabric sleeve, soft liquid metal fabric sensor, and nonlinear hysteresis model reveal that they can effectively modulate the level of assistance for the wearer. The new technologies obtained from this work can be potentially implemented in emerging assistive applications, such as rehabilitation, defense, and industry.

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Thermomechanically active electrodes power work-dense soft actuators

Soft Matter ◽

10.1039/d0sm01399d ◽

2021 ◽

Author(s):

Angel Martinez ◽

Arul Clement ◽

Junfeng Gao ◽

Julia Kocherzat ◽

Mohsen Tabrizi ◽

...

Keyword(s):

Liquid Crystal ◽

Liquid Metal ◽

Chain Extender ◽

Design Work ◽

Liquid Crystal Elastomers ◽

Soft Actuators ◽

Dense Liquid

The effect of chain extender structure and composition on the properties of liquid crystal elastomers (LCE) is presented. Compositions are optimized to design work-dense liquid metal LCE composites that are operated with 100 mW power.

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A Family of Loss Distributions with an Application to the Vehicle Insurance Loss Data

Pakistan Journal of Statistics and Operation Research ◽

10.18187/pjsor.v15i3.2995 ◽

2019 ◽

pp. 731-744 ◽

Cited By ~ 1

Author(s):

Zubair Ahmad Ahmad ◽

Eisa Mahmoudi Mahmoudi ◽

G. G. Hamedani

Keyword(s):

Maximum Likelihood ◽

Financial Risk ◽

Maximum Likelihood Estimates ◽

Model Parameters ◽

Data Set ◽

Loss Model ◽

New Class ◽

Proposed Model ◽

Loss Distributions ◽

Loss Data

Actuaries are often in search of nding an adequate loss model in the scenario of actuarial and financial risk management problems. In this work, we propose a new approach to obtain a new class of loss distributions. A special sub-model of the proposed family, called the Weibull-loss model isconsidered in detail. Some mathematical properties are derived and maximum likelihood estimates of the model parameters are obtained. Certain characterizations of the proposed family are also provided. A simulation study is done to evaluate the performance of the maximum likelihood estimators. Finally, an application of the proposed model to the vehicle insurance loss data set is presented.

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A Bio-inspired Robotic Fish Fin with Mechanosensation Using Conductive Liquid-Metal-Infused Soft Actuators

2019 IEEE 9th Annual International Conference on CYBER Technology in Automation, Control, and Intelligent Systems (CYBER) ◽

10.1109/cyber46603.2019.9066766 ◽

2019 ◽

Author(s):

Zemin Liu ◽

Wenguang Sun ◽

Ziyu Ren ◽

Kainan Hu ◽

Tianmiao Wang ◽

...

Keyword(s):

Liquid Metal ◽

Robotic Fish ◽

Conductive Liquid ◽

Soft Actuators

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The quantification of type-2 prudence in asset allocation by the trustees of a retirement fund

Annals of Actuarial Science ◽

10.1017/s1748499516000026 ◽

2016 ◽

Vol 10 (2) ◽

pp. 169-202

Author(s):

Robert J. Thomson ◽

Taryn L. Reddy

Keyword(s):

Risk Aversion ◽

Asset Allocation ◽

Weighted Average ◽

Expected Utility Theory ◽

Model Parameters ◽

Defined Benefit ◽

Defined Contribution ◽

New Class ◽

Retirement Funds

AbstractIn this paper, consideration is given to the normative use of expected-utility theory for the purposes of asset allocation by the trustees of retirement funds. A distinction is drawn between “type-1 prudence”, which relates to deliberate conservatism on the part of actuaries in the setting of assumptions and the determination of model parameters, and “type-2 prudence”, which relates to the risk aversion of the trustees. The intention of the research was to quantify type-2 prudence for the purposes of asset allocation, both for defined-contribution (DC) and defined-benefit (DB) funds. The authors propose new definitions of the objective variables used as the argument of the utility function: one for DC funds and another for DB funds. A new class of utility functions, referred to as the “weighted average relative risk aversion” class is proposed. Practicalities of implementation are discussed. Illustrative results of the application of the method are presented, and it is shown that the proposed approach resolves the paradox of counter-intuitive results found in the literature regarding the sensitivity of the optimal asset allocation to the funding level of a DB fund.

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A Force Control Joint for Robot–Environment Contact Application

Journal of Mechanisms and Robotics ◽

10.1115/1.4043043 ◽

2019 ◽

Vol 11 (3) ◽

Cited By ~ 1

Author(s):

Qilong Wang ◽

Wei Wang ◽

Xilun Ding ◽

Chao Yun

Keyword(s):

Force Control ◽

Model Simulation ◽

Industrial Robot ◽

Artificial Muscle ◽

Hysteresis Model ◽

Link Length ◽

Nonlinear Hysteresis ◽

The Difference ◽

Parallel Configuration ◽

Improved Accuracy

Accurate and robust force control is still a great challenge for robot–environment contact applications, such as in situ repair, polishing, and assembly. To tackle this problem, this paper proposes a force control joint with a parallel configuration, including two identical four-bar linkages driven by linear springs to push up the output end of the joint, and a parallel-connected pneumatic artificial muscle (PAM) to pull down its output end. In the new design, the link length of the linkages will be optimized to make the difference between the profile of the linkage and that of PAM constant within the limits of the joint given the force–displacement profile of PAM at a certain level of its input pressure. Furthermore, PAM's nonlinear hysteresis effect, which is believed to limit the accuracy of the joint's force control, will be represented by a new dynamics model that is to be developed from the classical Bouc–Wen (BW) hysteresis model. Simulation tests are then conducted to reveal that the adoption of the PAM hysteresis model yields improved accuracy of force control, and a series of curve trajectory tracking experiments are performed on a six-joint universal industrial robot to verify that the parallel force control joint is capable to enhance force control accuracy for robot contact applications.

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A New Extended-F Family: Properties and Applications to Lifetime Data

Journal of Mathematics ◽

10.1155/2020/5498638 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Saima K. Khosa ◽

Ahmed Z. Afify ◽

Zubair Ahmad ◽

Mi Zichuan ◽

Saddam Hussain ◽

...

Keyword(s):

Maximum Likelihood ◽

Maximum Likelihood Estimators ◽

Real Data ◽

Model Parameters ◽

Additional Parameter ◽

Alpha Power ◽

New Approach ◽

New Class ◽

Mathematical Properties ◽

Extended Weibull Distribution

In this article, a new approach is used to introduce an additional parameter to a continuous class of distributions. The new class is referred to as a new extended-F family of distributions. The new extended-Weibull distribution, as a special submodel of this family, is discussed. General expressions for some mathematical properties of the proposed family are derived, and maximum likelihood estimators of the model parameters are obtained. Furthermore, a simulation study is provided to evaluate the validity of the maximum likelihood estimators. Finally, the flexibility of the proposed method is illustrated via two applications to real data, and the comparison is made with the Weibull and some of its well-known extensions such as Marshall–Olkin Weibull, alpha power-transformed Weibull, and Kumaraswamy Weibull distributions.

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Design and Experimental Validation of a Metacomposite Made of an Array of Piezopatches Shunted on Negative Capacitance Circuits for Vibroacoustic Control

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Integrated System Design and Implementation ◽

10.1115/smasis2013-3182 ◽

2013 ◽

Author(s):

F. Tateo ◽

M. Collet ◽

M. Ouisse ◽

M. N. Ichchou ◽

K. A. Cunefare

Keyword(s):

New Technologies ◽

Control Method ◽

Low Frequency ◽

Elastic Solid ◽

Numerical Approach ◽

Anomalous Behavior ◽

Phononic Crystals ◽

Underlying Structure ◽

Negative Capacitance ◽

New Class

In the last few decades, researchers have given a lot of attention to new engineered materials with the purpose of developing new technologies and devices such as mechanical filters, low frequency sound and vibration isolators, and acoustic waveguides. For instance, elastic phononic crystals may come to mind. They are materials with elastic or fluid inclusions inside a matrix made of an elastic solid. The anomalous behavior in phononic crystals arises from interference of waves propagating within an inhomogeneous material. The inclusions inside the matrix cause strong modifications of scattering properties. However, the application of phononic crystals is still limited to sonic frequencies. In fact, band gaps can be generated only when the acoustic wavelength is comparable to the distance between the inclusion. In order to overcome this limitation, a new class of metamaterial has been proposed: meta composite. This new class of material can modify the dynamics of the underlying structure using a bidimensional array of electromechanical transducers, which are composed by piezo patches connected to a synthetic negative capacitance. In this study, an application of the Floquet-Bloch theorem for vibroacoustic power flow optimization will be presented. In the context of periodically distributed, damped 2D mechanical systems, this numerical approach allows one to compute the multimodal waves dispersion curves into the entire first Brillouin zone. This approach also permits optimization of the piezoelectric shunting electrical impedance, which controls energy diffusion into the proposed semiactive distributed set of cells. Experiments performed on the examined structure illustrates the effectiveness of the proposed control method. The experiment requires a rectangular metallic plate equipped with seventyfive piezopatches, controlled independently by electronic circuits. More specifically, the out-of-plane displacements and the averaged kinetic energy of the controlled plate are compared in two different cases (control system on/off). The resulting data clearly show how this proposed technique is able to dampen and selectively reflect the incident waves.

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Soft Planar Actuator using Pneumatic-Rubber Balls

Journal of Robotics and Mechatronics ◽

10.20965/jrm.2000.p0254 ◽

2000 ◽

Vol 12 (3) ◽

pp. 254-260 ◽

Cited By ~ 5

Author(s):

Toshiro Noritsugu ◽

◽

Daijyu Kaneshiro ◽

Takashi Inoue

Keyword(s):

Elastic Deformation ◽

Silicone Rubber ◽

Control Method ◽

Fundamental Principle ◽

Compressed Air ◽

Rubber Tube ◽

Carrier System ◽

Soft Actuator ◽

System A ◽

Soft Actuators

The manipulation of fragile and shapeless objects requires an actuator with enough flexibility and safety not to injure manipulated objects. To cope with such requirements, soft actuators have been developed, most of which utilize elastic deformation of a rubber tube or balloon caused by compressed air pressure. Such a pneumatic rubber actuator is expected to be effectively used as a flexible and friendly soft actuator in various fields. In this study, to realize a flexible pneumatic carrier system, a soft planar actuator using rubber balls has been developed assuming that the actuator directly contacts carried objects. This paper describes a fundamental principle of operation, a control method and experimental results. Additionally, a small sized soft planar actuator made of silicone rubber is described. The results show the effectiveness of the proposed actuator mechanism.

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