High Torque Research Articles

Design and shape optimization of interior permanent magnet synchronous machine based on hybrid cores

By designing stator teeth using grain-oriented sheets (GO) and other parts still with non-grain-oriented sheets (NGO), the electromagnetic performance of the interior permanent magnet synchronous machine (GO-IPMSM) can be improved greatly. As the stator core of the designed GO-IPMSM is a hybrid core that is composed of two different silicon sheets, both the electromagnetic and mechanical performances are affected by the stator joint shape between GO and NGO sheets. Meanwhile, with the adoption of GO, the torque ripple of GO-IPMSM is increased though the average torque is increased as well. For reducing the torque ripple, optimizing the rotor barrier shape is an effective way. In this paper, the piecewise linear interpolation method is employed for establishing the stator joint shape between GO and NGO sheets, and the polynomial method is proposed to establish the rotor barrier shape. Through the analysis, it can be seen that the stator joint shape plays a strong role in affecting the mechanical performance of the GO-IPMSM, while the effect on the electromagnetic performance is weak. The genetic algorithm is used to optimize the rotor barrier shape for achieving high average torque and low torque ripple. Lastly, a quick and accurate efficiency map calculation method based on the Kriging model is proposed for GO-IPMSM with less finite element method (FEM) samples are required.

Theory analyses and experimental study on starting torque and seal capacity of magnetic fluid seal using in low temperature

Magnetic fluid seal(MFS) is one of the most mature applications of magnetic fluid(MF) and is widely used in numerous fields. When applying the MFS at − 55 ℃(the low temperature), it will lead to a high initial torque situation and a noticeable seal capacity reduction. This situation results in sealing failure and impedes the normal device startup. In this study, we synthesized MF based on polyalpha-olefins-3.5 (PAO-3.5), demonstrating fluidity at − 55 ℃, a saturated magnetization of 46.7 kA/m, and stability exceeding 2 months. The low pour point of PAO-3.5 based MF positions them as a good material choice for MFS applications in low temperature. And a structure of field-controlled MFS to control the magnetic field in sealing gap was proposed. To emphasis the necessity of the control of magnetic field, empirical equations were employed to model the viscosity and yield stress of MF under varying magnetic field strengths and temperatures, explaining the impacts of these factors. And the starting torque of MFS in specific conditions can be predicted. Notably, the use of field-controlled MFS have decreases in starting torque during non-pressure-resistant scenario, pressure-resistant scenario and long-term use.

Asymmetric fin shape changes swimming dynamics of ancient marine reptiles’ soft robophysical models

Animals have evolved highly effective locomotion capabilities in terrestrial, aerial, and aquatic environments. Over life’s history, mass extinctions have wiped out unique animal species with specialized adaptations, leaving paleontologists to reconstruct their locomotion through fossil analysis. Despite advancements, little is known about how extinct megafauna, such as the Ichthyosauria one of the most successful lineages of marine reptiles, utilized their varied morphologies for swimming. Traditional robotics struggle to mimic extinct locomotion effectively, but the emerging soft robotics field offers a promising alternative to overcome this challenge. This paper aims to bridge this gap by studying Mixosaurus locomotion with soft robotics, combining material modeling and biomechanics in physical experimental validation. Combining a soft body with soft pneumatic actuators, the soft robotic platform described in this study investigates the correlation between asymmetrical fins and buoyancy by recreating the pitch torque generated by extinct swimming animals. We performed a comparative analysis of thrust and torque generated by Carthorhyncus, Utatsusaurus, Mixosaurus, Guizhouichthyosaurus, and Ophthalmosaurus tail fins in a flow tank. Experimental results suggest that the pitch torque on the torso generated by hypocercal fin shapes such as found in model systems of Guizhouichthyosaurus, Mixosaurus and Utatsusaurus produce distinct ventral body pitch effects able to mitigate the animal’s non-neutral buoyancy. This body pitch control effect is particularly pronounced in Guizhouichthyosaurus, which results suggest would have been able to generate high ventral pitch torque on the torso to compensate for its positive buoyancy. By contrast, homocercal fin shapes may not have been conducive for such buoyancy compensation, leaving torso pitch control to pectoral fins, for example. Across the range of the actuation frequencies of the caudal fins tested, resulted in oscillatory modes arising, which in turn can affect the for-aft thrust generated.

High insertion torque versus regular insertion torque: early crestal bone changes on dental implants in relation to primary stability—a retrospective clinical study

The aim of the presented retrospective study was to evaluate the early crestal bone changes around an implant type designed for high primary stability. A total number of 111 implants placed clinically were evaluated regarding insertion torque, bone density, implant stability quotient (ISQ) and early crestal bone loss from standardized digital radiographs. The implants were allocated in two groups: the „regular torque “ group contained all implants that achieved less than 50 Ncm as final insertion torque (n = 63) and the „high torque“ group contained the implants that achieved 50–80 Ncm (n = 48). To avoid possible damage either to the implant´s inner connection or to the bone by application of excessive force, a limit of 80 Ncm was set for all surgeries. All implants underwent submerged healing for three months. ISQ measurements and standardized digital radiographs were taken at day of insertion and at day of second stage surgery. The bone loss was measured on the mesial and distal aspect of the implant. The data evaluation showed the following results: Mean bone loss was 0.27 ± 0.30 mm for the high torque group and 0.24 ± 0.27 mm for the regular torque group. The difference was not statistically significant (p = 0.552). In the two groups, no complications nor implant loss occurred. For the evaluated implant type, there was no significant difference in crestal bone changes and complication rate between high and regular insertion torque in the early healing period.Graphical

Nonlinear optimal control for robotic exoskeletons with electropneumatic actuators

Nonlinear optimal control for robotic exoskeletons with electropneumatic actuators

Selective recruitment of the triceps surae muscles in plantar flexion assessed by diffusion weighted magnetic resonance imaging

Introduction: The triceps surae muscles, including medial and lateral gastrocnemius (MG, LG) and soleus (SOL), play a major role in supporting walking activities. Up to now, the potential selective recruitment of the muscles in walking of different intensities has not been investigated quantitatively. Such knowledge and its in vivo assessment would enable precise monitoring of subject’s performance in therapy. In this study, we measured apparent diffusion coeffcient (ADC) in the muscles of healthy subjects after plantar flexion of different intensities, and hypothesized that the different muscles would be selectively recruited in the exercises. Methods: 8 subjects were recruited. In a 3T MRI, subject performed straight-leg plantar flexion with load of 15 lbs for 3 minutes (moderate intensity), and the same exercise with load of 30 lbs until exhaustion (high intensity). Before and after each exercise, DWI of the right calf was performed: b values 0, 400 s/mm2, TE 70 ms, TR 4000 ms, 12 directions. In post-processing, ADC (unit: 10−6 mm2/s) was averaged for MG, LG and SOL. Results: In MG, ADC of 1580±12.3 before exercise increased to 1910±18.8 (p<0.01) and 2010±13.5 (p<0.01) after the moderate-and the high-intensity exercise, respectively. In LG, ADC of 1600±11.8 before exercise increased to 1900±14.8 (p<0.01) after the moderate-intensity exercise, and stayed stable at 1940±27.8 (P=0.30) after the high-intensity one. In SOL, ADC remained stable after the moderate-intensity exercise (from 1660±80.2 to 1660±11.5, P=0.26), and significantly increased to 1790±25.1 (p<0.01) after the high-intensity exercise. Discussion: The findings with MG and LG agree with expectation that muscle is more water-diffused with increased exercise intensity, and the association diminishes as exercise intensity increases. The higher ADC in MG than in LG at high intensity may be attributed to how the two heads attach to the Achilles tendon differently. The more linear attachment of MG to the tendon could enable higher effciency in achieving high torque. Attaching to tibia and fibula, SOL is not supposed to support straight-leg plantar flexion, as verified in its response after the moderate-intensity exercise. Surprisingly, SOL’s ADC increased after the high-intensity exercise. Besides the increased cardiac output as a possible cause, anatomical features of SOL may enable it to truly assist the exercise. First, similar to MG, SOL attaches to the Achilles tendon linearly, making its torque transfer effcient. Second, with more slow-twitch fibers than gastrocnemius, SOL’s activation is more economical in prolonged exercise. In conclusion, this study provided evidence that the triceps surae muscles are selectively recruited in straight-leg plantar flexion of different intensities, presumably to achieve maximal metabolic effciency. This work was supported by National NSF of China (#82171924, JLZ). No conflicts of interest, financial or otherwise, are declared by the authors. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Experimental study of motor cycle performance with exhaust manifold using torque expansion chamber

The Motorcycle performance can be improved by modifying the intake manifold and exhaust manifold. In this research, the exhaust manifold was modified using a Torque Expansion Chamber (TEC), namely adding a tube to the exhaust manifold with a certain geometry and dimensions so that the heat carried by the exhaust gas is retained and does not directly escape through the exhaust. This test aims to determine the performance of a motorbike with a modified exhaust manifold by adding 250 mm tubular TEC. TEC installation with placement at 40%, 50%, and 60% of the exhaust manifold length. Engine performance including torque, power and specific fuel consumption is measured using the Dyno Test. The research results show that the use of the Torque Expansion Chamber has an effect on motorbike performance. Highest torque with 50% TEC placement and 60% TEC placement at 5000 rpm. Highest power with 50% TEC placement and 60% TEC placement at 6000 rpm to 6500 rpm. Lowest specific fuel consumption with 50% TEC placement at 6000 rpm

Torque Calculation and Dynamical Response in Halbach Array Coaxial Magnetic Gears through a Novel Analytical 2D Model

Coaxial magnetic gears have piqued the interest of researchers due to their numerous benefits over mechanical gears. These include reduced noise and vibration, enhanced efficiency, lower maintenance costs, and improved backdrivability. However, their adoption in industry has been limited by drawbacks like lower torque density and slippage at high torque levels. This work presents an analytical 2D model to compute the magnetic potential in Halbach array coaxial magnetic gears for every rotational angle, geometry configuration, and magnet specifications. This model calculates the induced torques and torque ripple in both rotors using the Maxwell Stress Tensor. The results were confirmed through Finite Element Analysis (FEA). Unlike FEA, this analytical model directly produces harmonics values, leading to faster computational times as it avoids torque calculations at each time step. In a case study, a standard coaxial magnetic gear was compared to one with a Halbach array, revealing a 14.3% improvement in torque density and a minor reduction in harmonics that cause torque ripple. Additionally, a case study was conducted to examine slippage in both standard and Halbach array gears during transient operations. The Halbach array coaxial magnetic gear demonstrated a 13.5% lower transmission error than its standard counterpart.

Improving Speed Characteristics of High-Torque-Density Motors for Physical Human–Robot Interaction Using an Independent Three-Phase Winding Structure

Recently, due to the decrease in labor force, increase in labor costs, and the desire for improved quality of life, research on robots has been actively conducted to address these issues. However, it is currently difficult to find robots that physically interact with humans. The reason is that the actuators of robots do not have a high torque density on their own. To solve this problem, high-torque-density motors, such as proprioceptive actuators, are being researched. However, the torque density is still insufficient for physical interaction with humans, so a motor with higher torque density has been developed. However, high-torque-density motors have the disadvantage of lower speed characteristics due to increased Back EMF levels. Therefore, to address the deterioration of speed characteristics in the developed motor, we applied the independent three-phase winding structure to improve the speed characteristics. Consequently, through comparison with the Y-Connection and D-Connection, we propose the most suitable winding structure for high-torque-density motors intended for physical interaction with humans.

Study on Performance Improvement through Reducing Axial Force of Ferrite Double-Layer Spoke-Type Permanent Magnet Synchronous Motor with Core Skew

Recently, due to the price fluctuation and supply instability of rare earth mineral resources, there has been a lot of development of electric motors using non-rare-earth permanent magnets. As a result, motors using Dy-free permanent magnets and ferrite permanent magnets are being researched, and, in particular, ferrite permanent magnets often utilize spoke-type structures, which are magnetic flux concentrators, to compensate for their low coercivity and residual flux density. However, in general, spoke-type PMSMs do not use much reluctance torque, so double-layer spoke-type PMSMs have been studied for their more efficient design. Unlike general spoke-type PMSMs, double-layer spoke-type PMSMs can utilize high reluctance torque by increasing the difference between d-axis and q-axis reluctance. However, as the difference in magnetic resistance increases, vibration and noise are generated, which adversely affects the mechanical part and shortens the life of the motor. Although this problem seemed to be solved by applying core skew in the previous study, it was confirmed that the axial force caused by the axial leakage flux occurred in the maximum torque per ampere (MTPA) control section and the torque ripple was increased. Therefore, in this paper, a model that can apply symmetrical core skew and reduce axial force is proposed. First, the causes of the axial force generated in previous studies were analyzed. Based on the analysis of these causes, a new symmetrical core skew structure was proposed, and its justification was verified through FEA.

Influence of Vertical Load, Inflation Pressure, and Driving Speed on the Emission of Tire–Road Particulate Matter and Its Size Distribution

As fleet electrification progresses, vehicles are continuously becoming heavier, while the used electric motors, with their high torques, enable longitudinal dynamics to be maintained or even increased. This raises the question of what effect electric vehicles have on the emission of tire–road particulate matter (PM). To answer this question, investigations were carried out in this study on a tire internal drum test bench with real road surfaces. In addition to the vertical load, the tire inflation pressure and the driving speed were varied. PM emissions were recorded in real time, resulting in emission factors (emission per kilometer driven) for different load conditions. This allows statements to be made about both the effect on the total emission and on the particle size distribution. It was shown that the PM emission increases linearly with the vertical load at constant longitudinal dynamics. If the tire inflation pressure is increased, the emission also increases linearly, and the increases in emission are equally large for both influences. A clear influence of the driving speed on the emission factor could not be determined. With regard to the particle size distribution, the following correlations were found: higher vertical load and higher tire inflation pressure result in a larger mean particle diameter, while a higher driving speed reduces it. Thus, this study contributes to a better understanding of the expected changes in tire-road PM emissions as a result of electrification.

Robust Combined Adaptive Passivity-Based Control for Induction Motors

The need for industrial and commercial machinery to maintain high torque while accurately following a variable angular speed is increasing. To meet this demand, induction motors (IMs) are commonly used with variable speed drives (VSDs) that employ a field-oriented control (FOC) scheme. Over the last thirty years, IMs have been replacing independent connection direct current motors due to their cost-effectiveness, reduced maintenance needs, and increased efficiency. However, IMs and VSDs exhibit nonlinear behavior, uncertainties, and disturbances. This paper proposes a robust combined adaptive passivity-based control (CAPBC) for this class of nonlinear systems that applies to angular rotor speed and stator current regulation inside an FOC scheme for IMs’ VSDs. It uses general Lyapunov-based design energy functions and adaptive laws with σ-modification to assure robustness after combining control and monitoring variables. Lyapunov’s second method and the Barbalat Lemma prove that the control and identification error tends to be zero over time. Moreover, comparative experimental results with a standard proportional–integral controller (PIC) and direct APBC show the proposed CAPBC’s effectiveness and robustness under normal and changing conditions.

Development of a Three-Finger Adaptive Robotic Gripper to Assist Activities of Daily Living.

A significant number of individuals in the United States use assistive devices to enhance their mobility, and a considerable portion of those who depend on such aids require assistance from another individual in performing daily living activities. The introduction of robotic grippers has emerged as a transformative intervention, significantly contributing to the cultivation of independence. However, there are few grippers in the fields, which help with mimicking human hand-like movements (mostly grasping and pinching, with adoptive force control) to grasp and carry objects. Additionally, the data are not available even on how many Activities of Daily Living (ADL) objects they can handle. The goal of the research is to offer a new three-fingered gripper for daily living assistance, which can both grasp and pinch with adaptive force, enabling the capabilities of handling wide-ranging ADL objects with a minimal footprint. It is designed to handle 90 selective essential ADL objects of different shapes (cylindrical, irregular, rectangular, and round), sizes, weights, and textures (smooth, rough, bumpy, and rubbery). The gripper boasts a meticulously engineered yet simple design, facilitating seamless manufacturing through 3D printing technology without compromising its operational efficacy. The gripper extends its functionality beyond conventional grasping, featuring the capability to pinch (such as holding a credit card) and securely hold lightweight objects. Moreover, the gripper is adaptable to grasping various objects with different shapes and weights with controlled forces. In evaluation, the developed gripper went through rigorous load tests and usability tests. The results demonstrated that the users picked and placed 75 objects out of 90 daily objects. The gripper held and manipulated objects with dimensions from 25 mm to 80 mm and up to 2.9 kg. For heavy-weight objects (like books) where the centroid is far apart from the grasping areas, it is difficult to hold them due to high torque. However, objects' textures have no significant effect on grasping performance. Users perceived the simplicity of the gripper. Further investigation is required to assess the utility and longevity of grippers. This study contributes to developing assistive robots designed to enhance object manipulation, thereby improving individuals' independence and overall quality of life.

Review On Evolution and Development of Electric Road Roller

The evolution and development of electric road rollers mark a significant advancement in the construction machinery industry, driven by the imperative of sustainable infrastructure development. This paper provides a comprehensive overview of the historical progression, technological innovations, and current trends shaping electric road rollers. Beginning with the early developments of steam-powered and diesel-driven road rollers, the transition towards electric propulsion systems is traced, highlighting the environmental benefits and operational efficiencies offered by electric models. An electric-applied road roller vehicle represents a sustainable and innovative solution for the construction industry. This eco-friendly equipment utilizes electric power to propel the roller, reducing carbon emissions and noise pollution compared to traditional fossil fuel-powered counterparts. The vehicle's design incorporates advanced technology, such as gear chain mechanism to maximize energy efficiency and extend battery life. With its quiet operation and reduced environmental impact, the electric road roller vehicle demonstrates a promising step towards greener construction practices, contributing to a cleaner and more sustainable future. Top of Form Keywords— Electric Road Roller, Battery, High torque dc motor, propulsion system, gear assembly, etc.

Design and Control Performance Optimization of Variable Structure Hydrostatic Drive Systems for Wheel Loaders

The traditional loader drive system is based on the hydraulic torque converter as the key component, and its gear is shifted through the coordination of the clutch and gearbox, which greatly increases power loss and operator fatigue. To address the above problem, a variable-structure hydrostatic drive system is proposed. This system adopts a closed-loop design and adjusts the displacement of the pump and dual motors to follow the throttle opening of the vehicle, achieving automatic gear shifting and smooth speed regulation. It can also automatically change the system structure according to the vehicle’s speed, meeting the vehicle’s demand for rapid switching output of high torque and high speed. At the same time, in the displacement matching control process, an adaptive sliding mode control scheme based on radial basis function neural network compensation is proposed. This scheme designs an adaptive hyperparameter update strategy according to the characteristics of the system to effectively compensate for changes in uncertain factors. Experimental results show that, compared to traditional drive systems, this system has the characteristics of simple operation, smooth speed regulation, and high fuel economy.

Development of High-Temperature Permanent Magnet Synchronous Motor for Autonomous Robotic Navigation: A Design and Finite Element Analysis Approach

The traditional industrial robots come with the prime mover, i.e. Electric Motors (EM) which ranges from a few hundred too few kilo watts of power ratings. However, for autonomous robotic navigation systems, we require motors which are light weighted with the aspect of high torque and power density. This aspect is very critical, when the EMs in robotic navigations are subjected to harsh high temperature survival conditions, where the sustainability of the performance metrics of the electromagnetic system of the EMs degrade with the prevailing high temperature conditions. Hence, this research work address and formulate the design methodology to develop a 630 W High Temperature PMSM (HTPMSM) in the aspect of high torque and power density, which can be used for the autonomous robotic navigation systems under high temperature survival conditions of 200°C. Two types of rotor configurations i.e. the Surface Permanent Magnet type (SPM) and the Interior Permanent Magnet type (IPM) of HTPMSM are examined for its optimal electromagnetic metrics under the temperature conditions of 200°C. The 630 W HTPMSM is designed to deliver the rated torque of 2 Nm within the volumetric & diametric constraints of D x L which comes at 80 x 70 mm at the rated speed of 3000 rpm with the survival temperature of 200°C with the target efficiency of greater than 90%. The FEM based results are validated through the hardware prototypes for both SPM and IPM types, and the results confirm the effectiveness of the proposed design methodology of HTPMSM for sustainable autonomous robotic navigation applications.

Semi‐flooded cooling for high torque density modular permanent magnet machines

AbstractThe authors investigate a semi‐flooded cooling technology for modular permanent magnet machines using flux gaps (FGs) in alternate stator teeth for extra cooling channels. The investigated machine is separated into stationary and rotational components by a polyether ether ketone sleeve. Liquid is directed into the stationary component to achieve a significant temperature reduction, at the same time, avoiding the liquid leakage into the rotating component that will cause an increase in friction losses. The FGs in the modular machine increase the contact area between coolant and machine components, resulting in better cooling efficiency. Furthermore, the FGs contribute to reduced pressure loss by minimising system flow resistance. The influence of the FG width on improving machine cooling efficiency, lowering machine temperature, and reducing pressure losses is delved. Additionally, the investigation considers the impact of inlet and outlet areas to reveal the influences stemming from fluid expansions and contractions in these regions. Computational fluid dynamics (CFD) modelling is employed to simulate the cooling performances of the investigated machines. In addition, the flow network analysis has also been employed to help understand the fluid behaviour within machines. A series of tests have been carried out to validate the CFD modelling.

Investigation of torque and sensitivity analysis of a two-phase hybrid stepper motor

Abstract Stepper motors are extensively used in various automated systems, notably hybrid stepper motors (HSMs), renowned for their high torque density. Optimizing and improving their performance and torque density is highly beneficial. The first step in motor optimization is to perform a sensitivity analysis to identify the parameters most significantly affecting motor performance and torque density. Using Ansys Maxwell, a finite element method (FEM) software, we modeled and analyzed a commercially available HSM. After validating the computer model’s accuracy, we investigated the motor’s sensitivity to various parameters and discussed their effects on performance. Our findings highlight the significance of parameters such as air gap, magnet diameter, wire-turn numbers in the coils, and the shapes of the rotor and stator teeth in influencing HSM sensitivity—conversely, factors like magnet height and stator pole thickness exhibit negligible impact on motor performance.

AVIOANE ELECTRICE: PROVOCĂRI, OPORTUNITĂȚI, REALIZĂRI, TENDINȚE ACTUALE, PERSPECTIVE DE VIITOR

Electric vehicles are widely used in various transportation applications: automobiles, buses, ships, trains, unmanned aircraft vehicles (UAV), and airplanes. Rising greenhouse gas emissions and the risk of fossil fuel depletion have driven the transition to electric transport, which the European Union aims to reduce substantially by 2035 through renewable energies. In air transport, this transition is more difficult, especially due to the weight of the equipment on board. Without exception, they all use the energy stored in batteries to drive electric motors. In recent years, various hybrid drive systems have developed in aviation, systems based on fuel cells and environmentally friendly energy sources par excellence. Their main advantages are high efficiency, lightweight, modularity, and lack of moving parts. When fueled with hydrogen, they do not produce greenhouse gases, the only reaction products being water and heat. Axial magnetic flux motors have replaced the classic radial magnetic flux electric motors with low weight and volume, efficiency, power, and high torque previously developed for electric vehicles with in-wheel motors and are used without modification. This paper presents an overview of the main problems raised by electric propulsion of aircraft. Also, important achievements and development trends in the field are presented. Finally, a light, electrically powered aircraft configuration is proposed with a hybrid energy source composed of the hydrogen fuel cell, LiIon Polymer battery, and axial magnetic flux motor.

Gear Ratio Combination Analysis and Optimization for High Torque Density of Dual Magnetic Gear

Gear Ratio Combination Analysis and Optimization for High Torque Density of Dual Magnetic Gear