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The twisted string actuator (TSA) has been extensively studied as an alternative to metallic gear reducers due to its low-cost, lightweight, compliance, and highly adjustable actuation characteristics. Owing to these advantages, TSAs were utilized to realize lightweight human-robot interactive robots requiring safe interaction, such as wearables and prosthetics, at a relatively low cost. However, because its force transmission ratio is almost proportional to the length of the string, the string of the conventional TSA must be elongated to achieve high force output. Thus, it is difficult to obtain high force capacity while maintaining a small size. To overcome this limitation, we propose a novel TSA based on parallel bundle-driven actuation to significantly reduce the length of the TSA while achieving high force output. Furthermore, in order to boost the proposed TSA performance, we also present a passive mechanism of an asymmetric behavior compensator. The experimental results show that the force transmission ratio of the proposed TSA is increased by 21%, compared with that of the conventional TSA. Consequently, the proposed TSA has a 44% higher torque capacity with a 37% shorter string than those of the conventional TSA.

The three‐phase permanent magnet synchronous motor (three‐phase PMSM) has gained much popularity in many applications due to its various advantages. In addition, due to the good fault tolerance, simple inverter circuit structure and high torque density, the six‐phase PMSM has better prospects than three‐phase PMSM in biomedical devices, electric vehicles and other fields with high reliability requirements. In this study, a six‐phase axial‐flux PMSM inherently without cogging torque is proposed to improve torque density, which equips the 60° phase‐belt toroidal winding (60°TW) and slotless stator core. Based on the same effective volume, permanent magnet material, power grade and the other major motor parameters, two six‐phase PMSMs with 30° phase‐belt toroidal winding (30°TW) and 60°TW are designed, respectively. The armature reaction field, air gap magnetic density, back‐electromotive force, output torque, loss characteristic and torque‐speed characteristic are compared by using three‐dimensional (3D) finite‐element models in detail. Finally, the experimental test is carried out using the prototype of three‐phase PMSM with 120° phase‐belt toroidal winding. The experimental results indirectly verify the feasibility of 60° phase‐belt toroidal winding and correctness of 3D FEM. The 3D FEM analysis results are presented to show that torque density of the proposed six‐phase PMSM with 60°TW is improved in comparison to the six‐phase PMSM with 30°TW. Index Terms—60° phase‐belt toroidal winding, axial flux, six‐phase permanent magnet synchronous motor, torque density

Purpose Voltage fluctuation (flicker) is a power quality disturbance that can produce several undesirable effects on industrial equipment. This paper aims to present the methodology and results of investigations undertaken to examine the speed and torque of an induction motor (IM) under voltage fluctuation conditions. Design/methodology/approach The IM response to different characteristics of voltage fluctuations is presented. It will be shown that under a special condition the IM torque can even reach two times the rated torque. To show how this occurs, a qualitative discussion is given on the motor response by linearized equations. Findings The small-signal analysis was used to determine the frequency which leads to maximum speed fluctuations. It was shown that, if the motor is excited with a modulation frequency (resonant frequency) which is one of its natural frequencies (modes), the mode will act as a fluctuating amplifier and greatly increase the amplitude of torque and speed fluctuations. Sensitivity analysis is also carried out to evaluate the influence of motor parameters on the resonance frequency. The results show that the resonance frequency is not affected at all by the changes in magnetizing reactance. This has been shown that magnetic saturation does not have any impact on the resonance frequency. The most effective parameters are rotor and stator resistances. Originality/value With the increasing popularity and use of arc furnace loads in the metallurgy industry and due to the wide application of large IMs in the industry, it is possible that the frequency of torque pulsation locates near a natural frequency and then will create an oscillation with a large magnitude, potentially leading to accelerated fatigue or severe damage of shaft. However, if this phenomenon occurs in industries, the resonance frequency must be filtered from the input voltage. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole IM are used to validate the accuracy of simulation results.

Low‐speed and high‐torque direct‐drive permanent‐magnet motors have found wide applications primarily due to their outstanding performance characteristics. The special applications of these motors demand high reliability against the motor drive system, that is, the power system should have a certain level of fault tolerance. Therefore, the fault‐tolerant motor drive system has been the focus of research all over the world. Many fault‐tolerant motors can only deal with the open‐circuit fault of the winding or drive, and their capability of fault tolerance is substantially limited. When in operation, the short‐circuit fault caused by the ageing of winding insulation may result in more serious hazards than the open circuit in the winding. Such serious faults should be tolerated by the fault‐tolerant system. Moreover, the simpler maintenance or shutdown repair upon completion of fault‐tolerant operation of large‐sized fault‐tolerant motors should also be considered. Therefore, a permanent‐magnet fault‐tolerant motor with module combination stator (MCS‐PMFTSM) and unequal span winding is proposed. By changing the winding structure of the conventional motor the modular operation of the whole motor is achieved, which not only provides the motor with a high fault tolerance capacity but also reduces the downtime during repair and maintenance. In this work, the structure and operating principles of the MCS‐PMFTSM are described followed by the evaluation of the operation performances of the MCS‐PMFTSM under different fault conditions and various control strategies. The fault‐tolerant capacity of this new machine is then analysed, and the prototype is tested with a power of 12 kW and a rated speed of 100 r/min. Both theoretical analysis and test results demonstrate the outstanding operation performance and high fault tolerance of the motor.

Outer-rotor PM synchronous motor (OR-PMSM) with PM flux has shown to generate high torque and power densities. However, the round rotor used provides high iron loss and weight that affect their speed. This paper, addresses the problem using 24-stator and 14-segments flux switching machine (FSM) whose rotor is passive. Initially, performances of the designed motor such as cogging torque, harmonic distortion, average torque and power are analyzed. The initial design is optimized and the performances between initial and optimized OR-PMFSM designs are compared. The result shows OR-PMFSM has provided low cogging torque and low odd harmonic distortion to operate safely. The torque has increased to 48.81% from initial to optimize design of 240.5Nm and 469.8Nm. A comparative analysis of other motors for high torque such as OR-PMSM, OR-HEFSM and OR-FEFSM are presented. The proposed motor is capable to perform in high torque and high power conditions for automotive applications.

The ability to maintain an absolute, submaximal torque level during fatiguing contractions is controlled, in part, by the recruitment of larger motor units. These motor units are commonly identified based on greater action potential peak-to-peak amplitude values. It is unclear, however, if motor unit action potential (MUAP) amplitude values during low torque, fatiguing contractions reach similar levels as those observed during non-fatigued, high torque contractions. To establish a clearer understanding of motor unit control during fatigue, we compared MUAP amplitude during 50 and 80% maximum voluntary contraction (MVC) torque contractions and at the beginning, middle, and end of a 30% MVC fatigue protocol. Eleven untrained men (mean age = 24 years) performed isometric contractions at 50 and 80% MVC, followed by repeated contractions at 30% MVC. Surface electromyographic (EMG) signals were detected from the vastus lateralis and decomposed to quantify the peak-to-peak amplitude of individual MUAPs. A two-level multilevel model was estimated, allowing examination of simultaneous measures of MUAP amplitude within participants and controlling for the dependence between measures within participants. Results from the multilevel analyses suggested that there were not statistically significant differences in MUAP amplitude between 80% MVC and end fatigue. Separate repeated-measures analyses of variance indicated that there were not statistically significant mean differences in greatest MUAP or surface EMG amplitude between 80% MVC and end fatigue. MUAP and surface EMG amplitude values during a 30% MVC fatiguing protocol appear to be comparable to those observed during a non-fatigued 80% MVC condition.

The objective of this project is to vary the horse power and torque completely in motor bikes by using sprockets. Normally, sprockets can be manufactured based on the specifications of bike. This Project describes that the two sprockets with different dimensions used to vary the horse power and torque. Normally, the torque and Horse power can be defined as the ratio of output teeth to the input teeth. If the result value is between 2 and 2.5, then the Sprocket is designed for Purely Horse Power and when the result value is greater than 3, then it is surely produce high Torque. Whether the speed may be based on Horse Power or Torque. For Instance, if a 200 cc bike has a necessity to ride in a hills. The bike must be run in second or third gear. During second and third gear the engine needs more torque. A sprocket made for a horse power cannot produce sufficient torque to ride in a hills and fuel consumption is high. To overcome this problem, an input shaft which contains two sprockets of which one is purely for horse power and another one is purely for Torque. And the derailleur is introduced to shift the roller chain. Normally, Sprockets are made up of Cast Iron and Carbon Steels. In this work, instead of Cast Iron Sprocket, it is made up of 4140 Alloy Steel is used for Torque. A virtual model of Sprocket is designed by using CATIA 2018. Model is imported in ANSYS 15.0. The model has been analyzed and results have been recorded.

The main limitation of magnetic gears is their relatively low torque density. Therefore, a novel structured high torque density magnetic-geared permanent magnet (MGPM) machine, which combines the advantages of a conventional MGPM machine and magnetic gear to enhance the torque considerably and achieve low-speed high-torque operation, is proposed in this study. However, there are different structures for increasing torque of a machine. Therefore, in order to demonstrate the advantages of the proposed structure, it is compared with other structures, using the finite element method. Moreover, the proposed MGPM machine can transmit an additional 42.3% of torque density when compared with the conventional MGPM machine of the same size.

The design and the theory of calculation of the rocker oscillatory mechanism are presented, which provides an increase in more than 2 times the oscillation range of the oscillating shaft in comparison with the known oscillating mechanisms. The device allows to significantly increase the effectiveness of a high-torque non-frictiontype variator: it increases the variation range, reduces the cost of the design and reduces the metal consumption of the variator. Keywords: adjustable oscillating mechanism, cam non-friction high-torque variator mr.bvp1944@mail.ru

Introduction: Insertion torque imposes a direct effect on the stability of implants. Some studies suggest that high torque has resulted in bone necrosis while some suggest no impact on bone with high torque, the literature regarding insertion torque relationship to changes in bone is sparse. Purpose: The rationale of this article is to critically evaluate the available scientific data on influence of insertion torque on implant success. Materials and Methods: A Medline and manual search was done to recognize studies that are concerned with insertion torque related implant success rates from 1970 to 2017. The articles taken in this study includes data on insertion torque such as primary stability, bone quality and quantity, implant design and changes in bone related to high or low torque. Results: The 28 included studies contains one randomized controlled trial, 12 prospective studies and 10 retrospective studies. Conclusion: Insertion torque leads to primary stability of implants which ultimately contributes to implant success. Keywords: Insertion torque, Primary stability, Bone density, Implant success.

The use of direct-drive machines in renewable and industrial applications is increasing at a rapid rate. Transverse flux machines (TFMs) are ideally suited for direct-drive applications due to their high torque density. This article presents a comprehensive review of permanent magnet (PM) TFMs for direct-drive applications. It introduces TFMs and their operating principle and reviews the different types of TFMs proposed in the literature. TFMs are categorized by the number of stator sides, types of stator cores, and magnet arrangement in the rotor. The review covers different design topologies, materials used for manufacturing, structural and thermal analyses, modeling, design optimization, and cogging torque minimization in TFMs. The article also examines various applications and comparisons for TFMs presented in the literature.

The authors built a prototype motor with NANOMET stator cores. NANOMET is one of the several nanocrystalline soft magnetic alloys [see ref. 1]. Motor iron loss and other characteristics were compared with 35A360 (Japanese Industrial Standards), which is one of the widely used conventional electromagnetic steel sheet, and the effectiveness of the new material is shown. This study describes the method to build NANOMET stator cores, and presents the evaluation results of the prototype motor.

Powered knee exoskeletons aim to assist individuals with lower limb impairments by providing power and torque at the joint level. However, if the anatomical and exoskeleton joints are not perfectly aligned, the exoskeleton assistance may result in spurious forces and torques transferred to the user’s limb. These spurious forces and torques can then generate undesired loads on the user’s joint and shear stress on the user’s skin, causing pain and ultimately undermining the exoskeleton assistance. To address this issue, we propose a novel powered knee exoskeleton with a self-aligning mechanism using a prismatic-revolute-revolute (PRR) configuration. The proposed self-aligning mechanism weighs 190 g (i.e., 5.3% of the total exoskeleton weight) and can transmit up to 120 Nm of torque at the knee joint (i.e., biological peak torque for a 50th percentile male climbing stairs). Our experiments show that during assisted sit-to-stand transfers the peaks of the spurious torques and forces are below 0.5 Nm and 5 N, respectively, even if misalignments are intentionally added between the user and the exoskeleton. This study supports the use of self-aligning mechanisms in powered exoskeletons.

In this paper a method is introduced which models the resulting motor torque and current dynamics directly from the flux linkages. With the introduced method to process the flux linkage characteristics it is sufficient to calculate half of an electrical period to receive all information for modelling the system’s behaviour, even for both long and short flux path mutual coupling. The model is validated by 2D finite

With evolution of Electric drives design for electric vehicles, key aspects such as control, dynamic performance, efficiency and weight-torque ratio are some of the key parameters considered for optimization. Of these, torque to weight ratio is pivotal. As a typical traction load requires high starting torque and low torque during high speed, direct motor coupling may result in oversizing of motor or motor insufficient to drive desired load. Thus to optimize weight, size, cost and torque to weight ratio of an electric drive, gear system is used that provides high torque at standstill to start and accelerate the vehicle and high speed with required torque once the vehicle is set in motion. In this paper we aim to demonstrate Two-gear-Electric vehicle driven using induction motor with V/F control where it will be apparent how use of gear box optimises electric drive rating and related parameters.

In this article, a novel exterior-rotor multiple teeth enhanced-torque switched reluctance motor (SRM) is proposed, which exploits permanent magnets (PMs) inside the end teeth of the neighboring stator poles. First, the topology of the proposed motor, namely PM-SRM, is introduced and its working principle is illustrated. Then, based on the magnetic equivalent circuit (MEC) of the motor, it is proven that the PMs contribute to increase the air-gap flux density and regulate the stator poles flux density. As a result, the output torque of the motor is increased as well. The electromagnetic analyses of the proposed PM-SRM are performed using 3-D finite-element analysis. To validate the improved performance of the proposed PM-SRM, it is compared with its PMless counterpart and a classical 12/10-pole SRM in terms of the output torque and power, losses, and efficiency. It is shown that the proposed motor outperforms the two compared motors in terms of the output power and torque, and efficiency. Finally, a prototype of the motor is fabricated and tested to evaluate the predicted results. Both simulation and experimental results demonstrate the high torque and power production capability of the proposed PM-SRM.

Recently, a motor for an in-wheel system—which is advantageous when applied to electric vehicles and self-driving systems—has received much attention. In this paper, we propose an analysis and design method that can be used for an in-wheel motor. In-wheel motors require high torque density and a compact form factor to be wheel-mounted. To meet these requirements, an axial flux permanent magnet motor is proposed for the in-wheel system. The end-winding length of the coil is a key factor to be considered in this design. Hence, we propose a novel method to study the end-winding length. Due to the structural characteristics of an axial flux permanent magnet motor, a three-dimensional finite element analysis, which requires much time and expense, is essential. To solve this problem, we propose a novel analytical method combined with finite element analysis to mitigate the time and cost factors in the development of the axial flux permanent magnet motor. The magnetic saturation and the slot opening effect, which are considered during the analysis and design phase, are extremely difficult to analyze due to their nonlinearity. Therefore, a novel analytical method and algorithm, which can consider nonlinear effects, such as the magnetic saturation and slot opening, is proposed. The usefulness of the proposed analysis and design method and the axial flux permanent magnet motor for an in-wheel system were verified via 3D finite element analysis using a commercial simulation tool (JMAG).

A high gear ratio flux switching permanent magnet machine (HFSPM) was proposed to improve the torque performance in flux switching permanent magnet machine (FSPM). Conventional FSPMs address flux bypass issue when designed with a high gear ratio. The HFSPM adopts a dual rotor structure to overcome this flux bypass issue. First, the cause and effect of flux bypass issue was discussed using a magnetic equivalent circuit (MEC). Further, the process of overcoming the flux bypass issue using dual rotor structure was discussed. An alternative HFSPM, consequent pole HFSPM (CP-HFSPM), was proposed to enhance torque performance. The CP-HFSPM was optimized for high torque performance and proper power factor.

With an increase in the share of old and low-yield wells and for the efficient exploitation of fields, it is necessary to include low-capacity formations into production. There are many wells where sidetracking and hydraulic fracturing are difficult due to the close proximity of the gas cap and underlying water caused by geological and technological reasons, and the use of existing secondary drilling-in technologies is not effective due to the extensive colmatated zone or annular circulation. Relevance of radial drilling technologies is growing, which allows drilling-in of the formation with a network of extended channels to establish high-quality hydraulic communication between the formation and the well without affecting the permeability of the formation. In contrast to radial drilling technologies using hydraulic washing, technical system (TS) «Perfobur» uses small-sized screw downhole motors (SDM) and rock cutting tools for channel construction. For efficient milling of production casing and destruction of rock, the hydraulic downhole motor must have high torque, and for the possibility of drilling with a high rate of angle gain, it must have short power section. Existing Russian and foreign SDM have limited number of standard sizes and do not meet the requirements specified for the development of the downhole module of TS «Perfobur». The paper discusses the development of universal small-sized sectional screw downhole motors for milling casing strings and drilling a network of branched channels of super-small diameter and radius of curvature as a part of the TS «Perfobur». Methodology proposed in the article for selecting optimal configuration of the SDM power sections allows constructing small-sized sectional downhole motor that meets the technical requirements and has improved characteristics compared to standard SDM.

Recently, the in-wheel switched reluctance motor (IWSRM) has become one of the competitive in-wheel motors (IWMs) because of its advantages of low cost, high torque density, integrated configuration, direct drivetrain system, and efficient power transfer (Oksuztepe in IEEE Transactions on Vehicular Technology 66:4706–4715, 2017; Lin et al. in IEEE Transactions on Transportation Electrification 1:348–356, 2015). However, the use of IWMs including IWSRM, can undoubtedly increase the vehicle unsprung mass, causing vertical vibration and ride comfort problems of electric vehicles (EVs) (Li et al. in Mech Syst Signal Process 116:545–565, 2019).

Background A non-invasive method has recently been introduced to remove osseo-integrated palatal implants by using the implantation ratchet which is designed to screw in or unscrew the implants. Although a proof of concept has been published, the torque involved to successfully explant have not been investigated so far. The aim of this study was to assess the removal torque required to explant osseo-integrated and orthodontically utilized palatal implants, and to identify potentially influencing variables. Materials and method Thirty-one consecutive patients (15 females, 16 males; mean age 24.1 ±7.4 years) with fully osseo-integrated and previously orthodontically loaded palatal implants (Orthosystem®: diameter 4.1mm/length 4.2mm/sandblasted with large grits (SLA) surface) were randomly assigned to either clockwise or counter-clockwise non-invasive explantation. The respective explantation tool with an electric torque control was placed on the abutment connection of the implant and secured by an occlusal screw. The primary outcome studied was maximal removal torque (MRT) needed to detach the implant from its socket which was recorded individually together with other potentially influencing secondary outcomes (gender, age, orthodontic loading time, use of local anaesthetics). Student’s t-test was used to contrast MRT difference for the gender, type of suprastructure, use of local anaesthetics, and rotational direction. Spearman correlations was used to investigate associations between MRT and patient’s age or duration loading time. Results Average MRT (148.6 ± 63.2N/cm) using ratchet as a non-invasive removal method of palatal implant was considered safe. The triangular head fractured of palatal implant at a torque level of 300.1 Ncm. Significantly higher explantation were recorded for male patients compared to female patients (182.0 ± 63.0 Ncm vs 112.8 ± 40.8 Ncm; P=0.001). On the other side, the mean removal torque for palatal removal in clockwise direction was non-significantly different (158.3 ± 58.6 Ncm) compared to counter-clockwise direction (139.4 ± 67.9 Ncm). Neither patient’s age (p=0.324) nor loading time (p=0.214) were significantly correlated with removal torque values. Conclusions Pertinent literature on this subject is practically non-existent, as orthodontics is presumably the only discipline where implant removal represents a treatment success. Mean MRT for successful palatal implant removal was 148.6±63.2Ncm, but a large spectrum was observed (minimum 31.5Ncm, maximum 272.8Ncm). This obvious heterogeneity underlines the importance to investigate possible influencing factors. The safe and simple non-invasive method for palatal implant removal necessitates moderate, but not high torque MRTs, independently of the torque direction. The necessary MRT seems clearly influenced by gender, but less so by patient’s age or loading time.

The price fluctuation and the unstable supply chain of rare-earth permanent magnet (PM) have posed potential risks for further application of rare-earth PM motors. To alleviate the consumption of rare-earth PM material, a less-rare-earth PM brushless motor with two types of PM materials is proposed in this paper. The key of this motor is that the rare-earth PM is purposely combined with a non-rare-earth ferrite PM, forming the hybrid PM excitation. To design the proposed motor efficiently, a multi-objective stratified optimization strategy is proposed, where the selected five optimization objectives of output torque, PM cost, cogging torque, torque ripple, and efficiency are divided into two levels. Then, different optimization methods are skillfully combined to meet the specific design requirements. The corresponding electromagnetic performances are analyzed and compared with the baseline rare-earth PM brushless motor. Finally, several experiments of the two motors are carried out for evaluation. Both theoretical analysis and experimental results verify the feasibility and validity of the proposed motor and the optimization method.