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A common issue with many commercial rehabilitative exoskeletons and orthoses are that they can be prohibitively expensive for an average individual to afford without additional financial support. Due to this a user may have limited to the usage of such devices within set rehabilitation sessions as opposed to a continual usage. The purpose of this review is therefore to find which actuator implementations would be most suitable for a simplistic, low-cost powered orthoses capable of assisting those with pathologic gait disorders by collating literature from Web of Science, Scopus, and Grey Literature. In this systematic review paper 127 papers were selected from these databases via the PRISMA guidelines, with the financial costs of 25 actuators discovered with 11 distinct actuator groups identified. The review paper will consider a variety of actuator implementations used in existing lower-limb exoskeletons that are specifically designed for the purpose of rehabilitating or aiding those with conditions inhibiting natural movement abilities, such as electric motors, hydraulics, pneumatics, cable-driven actuators, and compliant actuators. Key attributes such as technical simplicity, financial cost, power efficiency, size limitations, accuracy, and reliability are compared for all actuator groups. Statistical findings show that rotary electric motors (which are the most common actuator type within collated literature) and compliant actuators (such as elastic and springs) would be the most suitable actuators for a low-cost implementation. From these results, a possible actuator design will be proposed making use of both rotary electric motors and compliant actuators. [ABSTRACT FROM AUTHOR]

The paper describes the design and testing of a new magnetorheological elastomer (MRE)-based actuator to reduce rotor vibrations. The core component of the actuator is a smart elastomer with the stiffness control through an external magnetic field; the support stiffness of the rotor can be adjusted to provide the suppression of the vibration when the rotor crosses the critical speed. We perform here a series of analysis related to the different functions of the components, the magnetic circuit and heat transfer to design the MRE actuator. A prototype of the MRE actuator has also been developed, and the generation of the magnetic field of the actuator and the rotor vibration suppression effect have been verified through experiments. The experimental results show that the MRE-based actuator provides a significant vibration reduction of the over-critical speed of the rotor when an external magnetic field is controlled via voltage. [ABSTRACT FROM AUTHOR]

This paper aims to present an effective fault diagnosis method-based detection for sensors, actuators, and system faults in a wind turbine machine. The proposed detection method is based on physical and analytical redundancy of sensors and actuators to generate the appropriate residuals between all measured variables. In this work, a crisp logic technique is used as classifier to investigate the main parts of the process including actuator and sensor faults. Using this logical procedure, we can detect different faults in blade pitch positions, drive train, and generator with converter for a wind turbine system. The obtained simulation results show the ability of this diagnosis method to identify faults effectively in the principal sub-systems of the studied wind turbine. [ABSTRACT FROM AUTHOR]

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Many temperature indicators or sensors show color changes for materials used in food and medical fields. However, they are not helpful for a color-blind person or children who lack judgment. In this paper, we introduce simply fabricated and more useful low-temperature indicator (~30 °C) for devices that actuates using paraffin-infiltrated multi-walled carbon nanotube (MWCNT) coiled yarn. The density difference of MWCNT yarn provides large strain (~330 %) when heat causes the melted polymer to move. Furthermore, the MWCNT yarn decreases the melting point of paraffin. These properties allow control of the actuating temperature. In addition, mechanical strength was enhanced by MWCNT than previously reported temperature-responsive actuators based on shape memory polymers. This simply fabricated temperature indicator can be applied in latching devices for medical and biological fields. [ABSTRACT FROM AUTHOR]

This paper presents the control strategy of a new type of mechanical actuator used to help in measuring hole surface parameter. The actuator can carry up to a load of 26 kg during measurement. Often, the measurement unit's attitude is misaligned due to the force acting on it. Actuator is used in order to control the misalignment of such system during measurement. In this research, the complete measurement system consists of a servo motor, a laser diode, a laser interferometer, an optical system, as well as an integrated computer system. The main purpose of this research is to develop the new type of actuator which can control the attitude (position and inclination) of a measurement probe. The experimental results show that it is possible to carry mechanically the loads up to 26 kg of the measurement probe during measurement of deep surface. In this paper, the developed actuator's control strategy has been discussed widely in order to measure the surface parameter successfully. [ABSTRACT FROM AUTHOR]

A Nitinol hydraulic bellows actuator for the application in minimally invasive surgeries (MIS) has been designed and manufactured. Such application required the actuator to be elastically deformable. This paper explains how the actuator geometry is optimized for large deformations and shows the feasibility of an actuator manufactured by selective laser melting (SLM). Four different shapes were virtually tested using finite element analyses (FEA). Furthermore, multiple samples of the bellows actuator with a U-shaped deformation zone were simulated and manufactured. A test rig was developed to measure deformation and achievable force. Physical tests showed a sufficient performance of the actuator for typical applications in minimal invasive surgery. Technical challenges and potential solutions on the current state of development are discussed. [ABSTRACT FROM AUTHOR]

The use of active prostheses for lower limb replacement brings new challenges like power optimization, energy efficiency and autonomy. The use of series and parallel elasticity is often explored to reduce the necessary motor power but this does not necessarily have a positive influence on the energy consumption of the prosthesis. This paper presents the experiments performed with the variable compliance actuator used in an active ankle prosthesis and the electromechanical model of this actuator. The results show that the measurements can be matched using the model, and this model can thus be used to optimize the energy efficiency of the actuator. Simulations show that the electrical efficiency can be increased by 10% compared to parameters selected by an optimization method that only takes mechanical properties into account. [ABSTRACT FROM AUTHOR]

For elderly and physically disabled people, support systems that assist their active daily life are as important as appropriate rehabilitation. We have designed a rotational meshing actuator for a life support system based on a mobile robot. The present paper explains the basic concept of the actuator and its design details. The actuator comprises a motor-controlled active mechanism mated with a passive mechanism. The trident pin on top of the active mechanism engages with a similar pin on top of the passive mechanism, transmitting the rotational motion between the mechanisms. The rotation transmission characteristics of the actuator were experimentally investigated using an actuator prototype. Finally, the developed actuator was mounted on a mobile robot, and its practical feasibility was confirmed by a window curtaining experiment. [ABSTRACT FROM AUTHOR]

In this paper, a new voltage induction synchronous electrostatic motor (VISE motor) is introduced, and its performance is analyzed using analytical modeling. In the proposed motor, compared to similar size electrostatic motors, the power is significantly improved by using active electrodes on both rotor and stator. Besides, the rotor's electrodes are charged indirectly (via induction electrodes supplied on both the rotor and stator) to eliminate the undesirable wiring system. This leads to the remarkable features of the new design, including the simplicity, compactness, and light weight despite the feasibility of providing contactless rotor. In order to investigate the performance, the approach of the capacitance coefficient matrix has been used in which the coefficients are numerically calculated using the finite element method. In addition, the induced voltages and torque equation of motor are analytically derived and verified using the fabricated prototype and experimental setup. Kinetics, design, and fabrication process of a prototype are presented, and some performance parameters of motor such as ripple, maximum speed, and synchronousness are experimentally examined. To improve the performance and smoothness of motor rotation, the skew design for rotor electrodes is used and evaluated by both modeling and experiments. There is an excellent agreement between the experimental observations and analytical results, both indicating the considerable improvement in the motor power. [ABSTRACT FROM AUTHOR]

This paper introduces an adapted high-speed high pressure torsion (HS-HPT) method of severe plastic deformation applied for obtaining shape memory alloy (SMA) active elements with revolution symmetry, able to develop axial displacement/force. Billets with circular crown forms were cut from Fe-28Mn-6Si-5Cr (mass%) SMA ingots and, by means of HS-HPT technology, were directly turned into modules, with truncated cone shell configurations. This process was performed, during time intervals of seconds, under the effect of high pressure (up to 1 GPa) cumulated with high rotation speed (hundreds of rotations per minute) applied on the active surfaces of sintered-carbide anvils, specially designed for this purpose. Due to pressure and friction, generated by rotation, the entire sample volume is heated and simultaneously deformed to final shape. During the process, microstructure fragmentation occurred enabling to obtain (ultra)fine grains and nanocrystalline areas, in spite of the heat developed by friction, which was removed by conduction at the contact surface between sample and anvils, before the occurrence of any recrystallization phenomena. When compressed between flat surfaces, the truncated cone modules developed a superelastic-like response, unique among Fe -Mn-Si base SMAs and, when heated in compressed state, they were able to develop either axial strokes or recovery forces by either free or constrained recovery shape memory effect (SME), respectively. By means of optical (OM) and scanning electron microscopy (SEM) marked structural changes caused by HT-HPT were revealed, along with fine and ultrafine crystalline grains. The presence of stress-induced ε-hexagonal close-packed ( hcp) martensite, together with nanocrystalline areas were confirmed by x-ray diffraction. [ABSTRACT FROM AUTHOR]

A medical cyber-physical system (MCPS) combines intelligent medical devices with a network. Nowadays, MCPS is extensively used in the healthcare system. While sharing patient data into MCPS, data security and privacy are significant challenges in healthcare as most of the devices suffer from data leaking, data manipulation, data forgery, denial of service attacks, etc. In this work, a reputation-based blockchain framework has been proposed to ensure patient data security while preserving privacy. A detailed security analysis discusses the possible attacks and the countermeasures of the attacks. The result and performance analysis of the proposed framework show low latency in data sharing and high throughput with an increasing number of users in the network. The calculated results established that the average latency time is reduced to (46–50%) while throughput is increased by (44–50%) as the number of users increases. [ABSTRACT FROM AUTHOR]

The 10th International Workshop on Piezoelectric Materials and Applications in Actuators (IWPMA) was held at the Gottfried Wilhelm Leibniz Universität Hannover from 14 July until 18 July 2013. This conference marked a milestone in the history of this series of symposia where distinguished scientists from all over the world come together and present their latest research work in the field of piezoelectric materials and piezoelectric actuators. [ABSTRACT FROM AUTHOR]

Traditional exoskeletons have made considerable contributions to people in terms of providing wearable assistance and rehabilitation. However, exoskeletons still have some disadvantages, such as being heavy, bulky, stiff, noisy, and having a fixed center of rotation that can be a burden on elders and patients with weakened muscles. Conversely, artificial muscles based on soft, smart materials possess the attributes of being lightweight, compact, highly flexible, and have mute actuation, for which they are considered to be the most similar to natural muscles. Among these materials, dielectric elastomer (DE) and polyvinyl chloride (PVC) gel exhibit considerable actuation strain, high actuation stress, high response speed, and long life span, which give them great potential for application in wearable assistance and rehabilitation. Unfortunately, there is very little research on the application of these two materials in these fields. In this review, we first introduce the working principles of the DE and PVC gel separately. Next, we summarize the DE materials and the preparation of PVC gel. Then, we review the electrodes and self-sensing systems of the two materials. Lastly, we present the initial applications of these two materials for wearable assistance and rehabilitation. [ABSTRACT FROM AUTHOR]

The time-dependent electro-viscoelastic performance of a circular dielectric elastomer (DE) membrane actuator containing an inclusion is investigated in the context of the nonlinear theory for viscoelastic dielectrics. The membrane, a key part of the actuator, is centrally attached to a rigid inclusion of the radius a, and then connected to a fixed rigid ring of the radius b. When subject to a pressure and a voltage, the membrane inflates into an out-of-plane shape and undergoes an inhomogeneous large deformation. The governing equations for the large deformation are derived by means of non-equilibrium thermodynamics, and viscoelasticity of the membrane is characterized by a rheological spring-dashpot model. In the simulation, effects of the pressure, the voltage, and design parameters on the electromechanical viscoelastic behaviors of the membrane are investigated. Evolutions of the considered variables and profiles of the deformed membrane are obtained numerically and illustrated graphically. The results show that electromechanical loadings and design parameters significantly influence the electro-viscoelastic behaviors of the membrane. The design parameters can be tailored to improve the performance of the membrane. The approach may provide guidelines in designing and optimizing such DE devices. [ABSTRACT FROM AUTHOR]

This work aims at the experimental characterization and modeling validation of shape memory alloy (SMA) Negator springs. According to the classic engineering books on springs, a Negator spring is a spiral spring made of strip of metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbor. The main feature of a Negator springs is the nearly constant force displacement behavior in the unwinding of the strip. Moreover the stroke is very long, theoretically infinite, as it depends only on the length of the initial strip. A Negator spring made in SMA is built and experimentally tested to demonstrate the feasibility of this actuator. The shape memory Negator spring behavior can be modeled with an analytical procedure, which is in good agreement with the experimental test and can be used for design purposes. In both cases, the material is modeled as elastic in austenitic range, while an exponential continuum law is used to describe the martensitic behavior. The experimental results confirms the applicability of this kind of geometry to the shape memory alloy actuators, and the analytical model is confirmed to be a powerful design tool to dimension and predict the spring behavior both in martensitic and austenitic range. [ABSTRACT FROM AUTHOR]

Children suffering from autism spectrum disorder are often reported to encounter sleeping disorder several causes such as hypersensitivity as result of irregular brain and muscle functions. Disturbance in sleep affects not only their health but also daytime activities including the risk of other cognitive and behavioral impairments. Such hindrance in sleep have been demonstrated to treat therapeutically by measures like application of deep pressure touch and full body vibration which can be beneficially integrated into the sleeping environment such as on the textile-based platform around the bed. With such a vision, this pilot design project aimed to develop a smart textile based sleeping bag incorporated with sensors to detect awakening stage of the child and thereby actuating stimuli for assuaging the child to fall asleep. To serve the purpose, a micro-controllable body movement detection sensor, based on conductive yarns connected to a vibrating motor was prosperously embedded at the interior of the sleeping bag along with weighted slots to exert deep touch and soothing sensation in the form of wearable technology. [ABSTRACT FROM AUTHOR]