Torque Loss Research Articles

Biomechanical analysis of maxillary anterior teeth movements during different retracting methods with a lever arm miniscrew system in double-slot lingual brackets: A finite element method study.

The objective of the study was to find the most effective retracting method for the six maxillary anterior teeth with double-slot lingual brackets using a lever arm and miniscrew system. Six finite element models were constructed: (A) a ribbon-wise archwire with a lever arm; (B) a ribbon-wise archwire with a lever arm and a sectional edgewise archwire; (C) a ribbon-wise archwire and a sectional edgewise archwire with a lever arm; (D) an edgewise archwire with a lever arm; (E) an edgewise archwire with a lever arm and a sectional ribbon-wise archwire; and (F) an edgewise archwire and a sectional ribbon-wise archwire with a lever arm. Initial displacements of maxillary teeth driven by a 1.5N retraction force to the lever arm were analysed. In models B, C, E and F, anterior torque loss and inter-canine distance increases were significantly lower than that of the models without auxiliary archwires. In models C and F, the main archwire was less likely deformed. In models A, B and C, the displacement of canines in sagittal and vertical directions were less than in models D, E and F. The combination of edgewise and ribbon-wise archwires in double-slot lingual brackets effectively preserves the anterior arch shape. An edgewise archwire with lever arms on the auxiliary sectional ribbon-wise archwire is recommended for better performance in anterior teeth retraction.

Method of calculation of electromagnetic torque and energy losses of three-phase induction motors when powered by a regulated single-phase voltage

Introduction. Single-phase power supply of induction motors is used in public utilities, in microclimate control systems for remote agricultural consumers, in water supply and pipeline transport systems, etc. In practice, there is the use of induction motors with three-phase stator winding in the conditions of single-phase power supply. Starting and operating capacitors are used to enable their operation when powered by a single-phase network. Problem. There are many fairly accurate methods for calculating the characteristics of an induction motor in asymmetric, including single-phase, modes of operation, but they are based on differential equations, which does not allow to obtain analytical expressions for preliminary analysis and synthesis of such systems. Goal. The purpose of this article is to develop the analytical method of definition of electromagnetic torque and energy losses of voltage-regulated three-phase induction motors working according to the scheme of single-phase inclusion with the phase-shifting capacitor. Methodology. The method is based on the theory of symmetric components and analysis of replacement schemes of induction machine in motor and generator modes. Results. The analysis of the obtained data shows that at a constant value of the phase-shifting capacitor capacity induction motor working according to the scheme of single-phase inclusion has a minimum of losses at one value of slip at different values of supply voltage. Therefore, if you keep this slip constant when the load changes, you can achieve a mode of minimizing losses at a constant value of the capacity, optimal for this slip. This shows that the thyristor voltage regulator can be used as an energy-saving element under variable load, while the capacitance of the phase-shifting capacitor can remain constant when changing the load in a wide range provided that this slip is stabilized. Originality. The developed method allows to obtain analytical expressions for comparative analysis of electromagnetic torque and energy losses of three-phase induction motors powered by a single-phase network at different values of the capacity of the phase-shifting capacitor, supply voltage for different variants of schemes for including three-phase induction motors in a single-phase network. Practical value. Based on the developed analytical method, the optimal parameters of phase-shifting capacitors and rational schemes for including three-phase induction motors in a single-phase network can be determined.

Optimal Control of a PHEV Based on Backward-Looking Model Extended with Powertrain Transient Effects

The paper proposes a power flow control strategy for a P2 parallel plug-in hybrid electric vehicle (PHEV) which takes into account torque and power losses related to engine-on and gear shift transients. An extended backward-looking (EXT-BWD) model is proposed to account for the transient losses, while the control strategy combines a rule-based controller with an equivalent consumption minimization strategy. To describe the transient losses, the EXT-BWD model includes additional state variables related to engine on/off flag and gear ratio in the previous time step. To establish a performance benchmark for control strategy verification, a dynamic programming-based control variable optimization framework is established based on the EXT-BWD model. The proposed control strategy is demonstrated to improve the fuel efficiency and drivability compared to the original control strategy while retaining comparable computational efficiency.

Development of a high-speed and low-torque loss two-way clutch

In this study, a two-way clutch mechanism using planetary gear meshing was proposed. The proposed mechanism allows low torque loss and high-speed rotation instead of a larger backlash compared to a roller type two-way clutch. The unique structure of this mechanism that makes such functionality possible comprises two independent planetary gears with variable distances between the axes. When the input shaft rotated, the planetary gears rotated at a distance. Torque is transmitted by the input shaft pushing directly on the output shaft, so losses on the tooth surface are small. As with gear reducers, high-speed rotation is possible. When the output shaft rotated, the two planetary gears engaged, and the shaft locked. A flat cam was used to switch between the above two states, so the overall structure was simple. The diameter, thickness, and weight of the developed prototype were 44 mm, 24 mm, and 78.8 g, respectively. We experimentally confirmed that the mechanism worked as expected. The theoretical locking limit torque was 1.16 Nm. The torque loss was 5 mNm at the static condition and less than 10 mNm at a high speed of 4000 rpm.

Effect of duplex treatment on the long-term stability of the abutment-implant interface by plasma nitriding and TiN coating

The purpose of this study was to evaluate the mechanical properties of abutments subjected to duplex treatment with arc plasma nitriding and physical vapor deposition (PVD) TiN coatings. The surface properties of abutments were analyzed. Then, the screw preload and microgap at the abutment-implant interface were measured. Screw loosening, abutment settlement, and abutment pullout force were tested before and after loading. The fatigue life of implant systems was compared. Finally, abutment surface wear and fatigue fracture surfaces were observed and analyzed. The results showed that duplex-treated abutment increased screw preload, interface contact area, loosening torque, and pullout force. Furthermore, the duplex-treated abutment exhibited good wear resistance and prolonged the fatigue life of implant systems. After cyclic loading, the screw torque loss rate decreased by 15.63 % and the abutment pullout force increased by 3 times. Therefore, duplex-treated abutments could effectively improve the long-term stability of the abutment-implant interface, which may be a suitable method for dental application.

Performance fatigability during isometric vs. concentric quadriceps fatiguing tasks in men and women

In the present study, we aimed to provide a robust comparison of the fatigability of the knee extensors following isometric (ISO) and concentric (CON) tasks. Twenty young adults (25 ± 4 yr, 10 women) randomly performed the ISO and CON quadriceps intermittent fatigue test, consisting of ten (5 s on/5-s off, ISO) or one-hundred (0.5-s on/0.5-s off, CON) contractions with 10 % increments per stage until exhaustion. Performance fatigability was quantified as maximal isometric (MVIC) and concentric (MVCC) torque loss. Voluntary activation and contractile function (peak-twitch) were investigated using peripheral nerve stimulation. Number of stages (6.2 ± 0.7 vs. 4.9 ± 0.8; P < 0.001) and torque-time integral (20,166 ± 7,821 vs. 11,285 ± 4,933 Nm.s; P < 0.001) were greater for ISO than CON. MVIC, MVCC and voluntary activation decreased similarly between sessions (P > 0.05) whereas peak-twitch amplitude decreased more for CON (P < 0.001). The number of contractions was similar across sexes (ISO: men = 62 ± 8, women = 61 ± 5; CON: men = 521 ± 67, women = 458 ± 76, P > 0.05). MVCC was more reduced in women for both sessions (all P < 0.05), while MVIC loss was similar between sexes. We concluded that, despite greater torque-time integral and duration for ISO, both sessions induced a similar performance fatigability at exhaustion. Contractile function was more altered in CON. Finally, sex-related difference in fatigability depends on the contraction mode used during testing.

Extended nonlinear time-varying lugre-based friction model identification of robot manipulator with sliding mode control compensation approach

In this article, the values of torque loss due to the friction phenomenon in the robot joints are initially identified; then, by considering the lugre friction model and applying the nonlinear least-squares error-estimation method, a model for this phenomenon is presented. To make the studies more efficient, the general lugre friction model has been used in three forms for modeling the system’s friction that the first model was the general lugre model, and in the other two Extended models, the parameters are considered as time variables that are estimated online. It should be noted that the third model includes the nonlinear viscous term too. Then, by using the nonlinear sliding mode controller, which is a robust control against possible uncertainties in the system, the performance of the designed algorithms is examined. The results show the superiority of the identified models with time-varying parameters over the model with constant parameters. Finally, by the use of represented friction models, a more accurate model for this system has been introduced. Eventually, the results of the simulations have been tested on a 6R laboratory robot to prove the validation of the results with the proposed algorithm, and as it showed, the final friction model has performed better.

Third-Order Effects and Maxillary Incisor Control in Lingual Orthodontics – A Finite Element Study of a Ribbon Arch and Edgewise Straight Wire System

Introduction: The aim of the present study was to analyze the effects of retraction mechanics on torque control when retraction forces were applied on the maxillary anterior dentition in two distinct lingual appliance systems. Materials and Methods: A three-dimensional bilateral maxillary model was created where the first premolar extraction case was included. 150 g (1.47 N) of retraction force was applied on each side from canine (C) hook to molar for both edgewise straight wire system and ribbonarch appliances. Results: In the edgewise appliance, it was observed in the X-axis that there was less amount of tipping of the six anterior teeth of the canine and central incisor (CI) when compared with the lateral incisor (LI) at occlusal point. In the Y-axis, overall extrusion was observed. In the Z-axis, there was less lingual crown movement. In the ribbonarch appliance, it was observed in the X-axis that there was less tipping, prominently in the canine and CI than in the LI. In the Y-axis, overall extrusion was observed. In the Z-axis, there was less lingual crown movement, whereas the CI and canine showed less movement when compared with the LI. Conclusions: It was observed that there was greater torque loss and extrusion in the edgewise appliance along with greater maximum principal stress in the cervical half of the facial side in the periodontal ligament (PDL) and minimum principal stress on the cervical half of the palatal side in the PDL when compared with the ribbonarch appliance.

Three-dimensional finite element analysis of upper anterior teeth retraction and intrusion using clear aligners and mini-implants.

This study aimed to investigate the differences in treatment outcomes of upper anterior teeth retraction and intrusion with clear aligners and different types of elastics on mini-implants via the 3D finite element method. Cone-beam computed tomography (CBCT) was conducted to construct a 3D finite element model of maxillary bone, dentition, and clear aligners using Mimics, Geomagic, Solidworks, and Ansys. Four model groups were developed. Group 1 was the control group. Group 2 implanted a mini-implant between the upper second premolar and the upper first molar with a force of 0.98 N applied to the canine cut along the retracting direction for each side. Group 3 was based on Group 2, which implanted an additional mini-implant between the upper central incisors with a force of 0.98 N applied to the upper anterior teeth cuts. Group 4 was also based on Group 2, which implanted 2 additional mini-implants between the upper central and lateral incisors with a force of 0.56 N applied to the upper anterior teeth cuts for both sides. Anterior teeth torque changes, displacement patterns, and stress distributions were analyzed. Among all the experimental groups, the anterior teeth demonstrated intrusion and distal inclination, accompanied with varied degrees of torque loss. In Group 3, the maxillary and lateral incisors had the smallest sagittal coronal displacement. In Group 4, the intrusion values of the maxillary and lateral incisors were the largest among all the experimental groups. The maximum stress concentration in Group 2 was the most significant among all the experimental groups. Implanting the mini-implant between the central incisors for traction is conducive to torque control. By contrast, implanting the mini-implants between the central incisors and lateral incisors combined with vertical traction is conducive to simple intrusion, avoiding the "bowing effect" to a certain extent.

고속 모터의 토크 리플 및 효율 개선을 위한 고정자 구조에 대한 연구

Recently, the demand for electric motors for high-speed operation is increasing due to the development of hydrogen vehicles using fuel cells as well as electric vehicles. In particular, the Air Blower Motor is receiving a lot of attention as an electric motor for hydrogen vehicles, and there is a need for performance improvement research on high-power, high-speed machines. In this paper, a coreless model with stator tooth removed was studied and designed to design a high-performance, high-speed motor. The purpose of this study was to increase the specific power of the motor by reducing the core usage and improve the efficiency by reducing the loss by improving the iron loss. It was verified that the torque ripple and loss of the coreless model were improved through the Finite Elements Method (FEM).

Finite element analysis of tie wings rotation: A new phenomenon in orthodontic bracket-archwire contact assembly during simulated torque.

In orthodontics, the torque generated forces from the rectangular archwires refine the teeth position. Literature shows only linear deformation in brackets during torqueing. The objective of this study was to evaluate a new phenomenon of tie wings rotation, an angular deformation in Stainless Steel (SS) brackets with SS and Beta-Titanium (β-Ti) archwires at various angles of twist. Maxillary central incisor SS 0.457 mm × 0.635 mm and 0.558 mm × 0.711 mm brackets, SS and β-Ti archwires of 0.431 mm × 0.635 mm and 0.533 mm × 0.635 mm sizes were used. Finite element analysis was performed in various bracket-archwire assemblies for simulated torque. Palatal root torque was applied and the gingival tie wings rotation was measured at selected points, from 5° to 30° angles of twist. The tie wings rotation for 30° twist with SS 0.533 mm × 0.635 mm archwire in 0.558 mm bracket ranged from 1.32° to 2.55° and with SS 0.431 mm × 0.635 mm archwire in 0.457 mm bracket from 0.71° to 1.73°. Similarly, with β-Ti 0.533 mm × 0.635 mm archwire in 0.558 mm bracket and β-Ti 0.431 mm × 0.635 mm archwire in 0.457 mm bracket, the tie wings rotation ranged from 0.73° to 1.38° and 0.39° to 0.93° respectively. The tie wings rotation were present in all the FE models. Higher archwire size, stiffness, and angles of twist showed increased rotation. Thus, clinicians should be aware of this tie wings rotation during torqueing as an additional factor for torque loss.

The impact of submaximal fatiguing exercises on the ability to generate and sustain the maximal voluntary contraction.

Neuromuscular fatigability is a failure to produce or maintain a required torque, and commonly quantified with the decrease of maximal torque production during a few seconds-long maximal voluntary contraction (MVC). The literature shows that the MVC reduction after exercises with different torque-time integral (TTI), is often similar. However, it was shown that after a fatiguing exercise, the decline in the capacity to sustain the maximal voluntary contraction for 1 min (MVC1-MIN) differs from the decrease in the capacity to perform a brief-MVC, suggesting that this latter can only partially assess neuromuscular fatigability. This study aims to highlight the relevance of using a sustained MVC to further explore the neuromuscular alterations induced by fatiguing exercises with different TTI. We used two contraction intensities (i.e., 20% and 40% MVC) to modulate the TTI, and two exercise modalities [i.e., voluntary (VOL) and electrical induced (NMES)], since the letter are known to be more fatiguing for a given TTI. Thirteen subjects performed a plantar-flexors MVC1-MIN before and after the fatiguing exercises. A similar MVC loss was obtained for the two exercise intensities despite a greater TTI at 40% MVC, regardless of the contraction modality. On the other hand, the torque loss during MVC1-MIN was significantly greater after the 40% compared to 20% MVC exercise. These findings are crucial because they demonstrate that maximal torque production and sustainability are two complementary features of neuromuscular fatigability. Hence, MVC1-MIN assessing simultaneously both capacities is essential to provide a more detailed description of neuromuscular fatigability.

Mechanical properties and marginal fit of prefabricated versus customized dental implant abutments: A comparative study.

Dental implant abutments play an important role in the health and aesthetics of soft and hard tissues around implants. To compare mechanical properties and marginal fit of prefabricated and customized dental implant abutments and provide references to evaluate the relationship between abutment choice and clinical indications. Titanium abutments were randomly divided into prefabricated and customized abutments. Static and dynamic loads were applied according to ISO14801:2016. Mechanical properties, including fracture strength, fatigue strength, rotational torque value, and torque loss rate, were measured. The biological properties of the implant abutments were assessed using an internal marginal fit. The samples were sliced, and the internal marginal fit was examined using a scanning electron microscope before and after cyclic loading. The length of the tight contact was calculated at the level of the conical connection, lower internal connection, and screw threads. Microleakage was evaluated by immersing the samples in 1% methylene blue and measuring the absorbance. The fracture strengths of the prefabricated abutments were greater than those of the customized abutments before and after cyclic loading. The average fatigue strengths of the prefabricated and customized abutments were 350 and 300 N, respectively. The removal torque loss of the customized abutments was significantly greater than that of the prefabricated abutments. Significant differences were found in conical connection before loading, while the screw threads showed substantial differences between the two groups after loading. Microleakage in the customized abutments was significantly higher than that in the prefabricated abutments before and after loading. Prefabricated abutments showed superior mechanical and biological properties compared with customized abutments in vitro, suggesting a greater risk of mechanical and biological complications occurring with the use of customized abutments. This study provides a reference for the clinical selection of implant abutments.

Development of Transaxle Fluid for Electrification Vehicles: Design of Novel Additive Formulation

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;To achieve carbon neutrality by reducing carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) emissions, vehicles with an internal combustion engine have started to be replaced by electrification vehicles such as hybrid electric vehicles (HEVs), plug-in HEVs (PHEVs), and battery EVs (BEVs) worldwide, which have motors in their transaxles (T/As). Reducing transmission torque loss in the transaxles is effective to reduce CO&lt;sub&gt;2&lt;/sub&gt; emissions, and lowering the viscosity of lubrication fluids in T/As is a promising method for reducing churning and drag loss. However, lowering viscosity generally leads to thin oil films and makes the lubrication condition severe, resulting in worse anti-fatigue and anti-seizure performance. To deal with these issues, we made improvements on the additive formulation of fluid, such as the addition of an oil-film-forming polymer, chemical structure change of calcium detergents, and an increase of anti-wear additives including phosphorus and sulfur. As a result, we succeeded in developing a novel fluid with greater lubricity than a conventional automatic transmission fluid (ATF), despite the fact that the viscosity of the new fluid was lowered by around 50% compared with that of the ATF. In addition, the electrical insulating and anti-foaming performance of this fluid, which are required for T/A fluid in electrification vehicles, were equal to or greater than those of the ATF. The fuel economy in the Toyota Hybrid System (THS) was improved by 1.0% and more compared with the ATF because of the significant viscosity decrease in the developed fluid. This fluid will be widely used for HEVs, PHEVs, BEVs, and fuel cell electric vehicles (FCEVs) and can contribute to the realization of a carbon-neutral society.&lt;/div&gt;&lt;/div&gt;

Five-Phase Hybrid Single-/Double-Layer Fractional Slot-Winding PMSM for Torque Improvement Under Third Harmonic Current Injection Condition

A 60-slot/22-pole five-phase machine with hybrid single-/double-layer fractional slot winding is proposed to improve torque under third harmonic current injection condition. Design process of the proposed machine includes two steps of first combining two sets of 20-slot/22-pole machine windings and then shortening coil-pitch. Due to the special structure of the proposed machine, torque-contributing space harmonics in magnetomotive force (MMF) are improved, and redundant space harmonic in MMF which causes high eddy current loss in permanent magnets is suppressed. The proposed machine is evaluated under two modes of third harmonic current injection, namely constant rms and peak harmonic injection. Compared with 20-slot/22-pole machine, the proposed machine achieves higher torque and lower losses under both third harmonic current injection conditions. Besides, the performance of the proposed machine when injecting only the first or third harmonic current is also analyzed.

Torque movement of the upper anterior teeth using a clear aligner in cases of extraction: a finite element study

BackgroundClear aligner treatment has become popular over recent years. It is necessary to identify methods by which we could avoid the bowing effect in extractions with clear aligner. The present study was to identify the appropriate method to design torque movement involving the upper anterior teeth of extraction cases, in order to maintain or improve the axis and torque of the upper anterior teeth with a clear aligner during movement and closure of the extraction space.ResultsAs the height of the power ridge increased, the rotation angle of the upper central incisor in the sagittal direction decreased gradually and the location of the rotation center changed significantly; the rotation center moved in the apical direction and then changed to the crown side. The highest von-Mises stress of the upper central incisor root, periodontal ligaments, and alveolar bone, showed little change as the power ridge height increased. When the axial inclination of the upper central incisor was normal (U1-SN = 105°), the tendency of movement for the upper central incisor approached translation with a power ridge height of 0.7 mm (corresponding distorted angle: 5.8415). When the axial inclination of the upper central incisor was oversized (U1-SN = 110°), the axial inclination of the upper central incisor reduced to normal following completion of the anterior segment retraction with a power ridge of 0.4 mm (corresponding distorted angle: 3.4265).ConclusionAnalysis indicates that pure palatal tipping movement of the upper anterior teeth is generated without torque control, thus resulting in the bowing effect. The required torque control of the upper anterior teeth with oversize axial inclination is weaker than that of the upper anterior teeth with normal axial inclination because limited torque loss is expected for oversize axial inclination teeth. Variation sensitivity of the rotation center should be considered carefully due to biological problems when designing translation of the upper anterior teeth with normal axial inclination.

Settling effect of abutment and torque loss in different types of abutment after cyclic loading.

This study aimed to evaluate and compare the settling effect of implant-abutment assembly and the torque loss before and after cyclic loading in three types of abutments. Thirty internal hexagon fixtures were randomly divided into three groups (n=10). Group A used original abutments, group B used pre-machined cast abutments, and group C used compatible abutments. In addition, the abutment morse taper angle was measured using an image measuring instrument. Removal torque values (RTVs) were recorded using a digital torque meter before and after cyclic loading. All samples were tested in a universal testing machine with a vertical load between 0 and 250 N for 100 000 cycles of 10 Hz. The settling effect was measured after cyclic loading. Paired t test was performed for intragroup analysis of removal torque loss before and after cycling and one-way ANOVA. Subsequently, Tukey's honestly significant difference test was used for intergroup comparison (α=0.05). The paired t-test showed signi⁃ficant differences in the intragroup RTVs before and after cycling (P<0.001). ANOVA showed significant differences in the mean of removal torque loss after cycling (P=0.009), the abutment morse taper angle (P<0.001), and the settling values (P=0.01) among different groups. However, no significant difference was found between compatible abutments and pre-machined cast abutments. The screw removal torque was significantly reduced for all groups in this study after cyclic loading. Differences could be found in the internal accuracy of implant-abutment assembly among different groups. Within the limitations of this study, the results showed the original abutments exhibited lower percentages of torque reduction after cyclic loading than the casting abutments and the compatible abutments.

Appropriateness of indirect markers of muscle damage following lower limbs eccentric-biased exercises: A systematic review with meta-analysis.

The aim of this review was to (1) characterize the time-course of markers of exercise-induced muscle damage (EIMD) based on the level of maximal voluntary contraction torque loss at 24-48h post-exercise (MVCloss24-48h), (2) identify factors (e.g., exercise and population characteristics) affecting the level of MVCloss24-48h, and (3) evaluate the appropriateness of EIMD markers as indicators of MVCloss24-48h. Magnitude of change of each EIMD markers was normalized using the standardized mean differences method to compare the results from different studies. Time-course of EIMD markers were characterized according to three levels of MVCloss24-48h based on a clustering analysis of the 141 studies included. Association between MVCloss24-48h levels and participant´s characteristics or exercise type/modalities were assessed. Meta-regressions were performed to investigate the associations between MVCloss24-48h and EIMD markers changes at <6h, 24h, 48h, 72h and >96h after exercise. Time-course of EIMD markers recovery differs between levels of MVCloss24-48h. Training status and exercise type/modality were associated with MVCloss24-48h level (p<0.05). MVCloss24-48h was correlated to changes in myoglobin concentration (<6h), jump height (24h) and range of motion (48h) (p<0.001). As the exercise could differently affect markers as function of the EIMD severity (i.e., MVCloss24-48h levels), different markers should be used as function of the timing of measurement. Mb concentration should be used during the first hours after the exercise (<6h), whereas jump height (24h) and range of motion (48h) could be used as surrogate for maximal voluntary contraction later. Moreover, training status and exercise type/modality could influence the magnitude of MVCloss24-48h.

Users Maintain Task Accuracy and Gait Characteristics During Missed Exoskeleton Actuations Through Adaptations In Joint Kinematics.

In operational settings, lower-limb active exoskeletons may experience errors, where an actuation that should be present is missed. These missed actuations may impact users' trust in the system and the adapted human-exoskeleton coordination strategies. In this study, we introduced pseudorandom catch trials, in which an assistive exoskeleton torque was not applied, to understand the immediate responses to missed actuations and how users' internal models to an exoskeleton adapt upon repeated exposure to missed actuations. Participants (N = 15) were instructed to complete a stepping task while wearing a bilateral powered ankle exoskeleton. Human-exoskeleton coordination and trust were inferred from task performance (step accuracy), step characteristics (step length and width), and joint kinematics at selected peak locations of the lower limb. Step characteristics and task accuracy were not impacted by the loss of exoskeleton torque as hip flexion was modulated to support completing the stepping task during catch trials, which supports an impacted human-exoskeleton coordination. Reductions in ankle plantarflexion during catch trials suggest user adaptation to the exoskeleton. Trust was not impacted by catch trials, as there were no significant differences in task performance or gait characteristics between earlier and later strides. Understanding the interactions between human-exoskeleton coordination, task accuracy, and step characteristics will support development of exoskeleton controllers for non-ideal operational settings.

Investigation of PM Loss in Spoke-Type Permanent Magnet Vernier Motors With Different Stator Topologies for In-Wheel Direct Drive

In this article, the permanent magnet (PM) loss in spoke-type permanent magnet vernier motors (ST-PMVM) with different stator topologies is investigated and compared for in-wheel direct drive. First, four ST-PMVM with split-pole and open-slot stators are designed for the in-wheel limited requirements. Besides, based on the PM loss model, the dominant influences of both slot and subharmonics on PM loss are highlighted. Then, the quantitative contributions of the air-gap magnetic field harmonics on torque and PM loss are investigated, which embodies the inherent characteristic of larger PM loss in PMVM. Furthermore, the stator tooth parameters, the slot opening width, and auxiliary slot depth on torque and PM loss are described, and then a parameter titled as the slot opening ratio is introduced to evaluate the relationship of various slot opening width combinations. It shows that there exists an irreconcilable contradiction between the torque and PM loss in PMVM, especially in split-pole types. Finally, a prototype was manufactured, and the theoretical results and finite-element analysis results match well with the experimental results.