Torque Parameters Research Articles

Photobiomodulation therapy is beneficial in reducing muscle fatigue in Brazilian jiu-jitsu athletes and physically active men

Photobiomodulation therapy (PBMT) applied prior to exercise may provide ergogenic effects by delaying the onset of fatigue. The Brazilian jiu-jitsu (BJJ) is a domain combat sport in which elbow flexors’ isometric contraction is commonly performed. This study was aimed at investigating the effects of PBMT on torque parameters in groups of BJJ athletes (n = 10) and physically active men (n = 10). The strength testing protocol was composed of elbow flexors’ maximal isometric voluntary contractions at 90°; treatment application (placebo or PBMT); fatigue protocol; and one elbow flexors’ maximal isometric voluntary contraction. Magnitude-based inference analyses were used to examine practical significance. BJJ athletes presented higher relative isometric peak torque values pre (ES = 0.92) and post (ES = 1.32) fatigue protocol than those observed in physically active men. Beneficial results were shown in the time to exhaustion (difference: 5.5 s, likely beneficial) and impulse during fatigue test (difference 271.1 N m s, possibly beneficial) for physically active men and in the impulse for BJJ athletes (difference 179.0 N m s, possibly beneficial) in favor of PBMT compared to placebo. The PBMT was efficient in delaying the onset of fatigue regardless of the individuals’ training level and could be suggested as an ergogenic factor to improve muscle performance.

Dependency of Head Impact Rotation on Head-Neck Positioning and Soft Tissue Forces.

Humans are susceptible to traumatic brain injuries from rapid head rotations that shear and stretch the brain tissue. Conversely, animals such as woodpeckers intentionally undergo repetitive head impacts without apparent injury. Here, we represent the head as the end effector of a rigid linkage cervical spine model to quantify how head angular accelerations are affected by the linkage positioning (head-neck configuration) and the soft tissue properties (muscles, ligaments, tendons). We developed a two-pivot manipulator model of the human cervical spine with passive torque elements to represent soft tissue forces. Passive torque parameters were fit against five human subjects undergoing mild laboratory head impacts with tensed and relaxed neck muscle activations. With this representation, we compared the effects of the linkage configuration dependent end-effector inertial properties and the soft tissue resistive forces on head impact rotation. Small changes in cervical spine positioning (<5 degrees) can drastically affect the resulting rotational head accelerations (>100%) following an impact by altering the effective end-effector inertia. Comparatively, adjusting the soft tissue torque elements from relaxed to tensed muscle activations had a smaller (<30%) effect on maximum rotational head accelerations. Extending our analysis to a woodpecker rigid linkage model, we postulate that woodpeckers experience relatively minimal head impact rotation due to the configuration of their skeletal anatomy. Cervical spine positioning dictates the head angular acceleration following an impact, rather than the soft tissue torque elements. This analysis quantifies the importance of head positioning prior to impact, and may help us to explain why other species are naturally more resilient to head impacts than humans.

A Study on Optimal Compensation Design for Meteorological Satellites in the Presence of Periodic Disturbance

Periodic disturbance may cause serious effects on the attitude of meteorological satellites, and the attenuation of periodic disturbance is required. In this paper, a fundamental study on the optimal design of constant compensations against known-law periodic disturbance for meteorological satellites is investigated. An analytical solution for the relationship between the frequency and amplitude ratios and the response of a typical second-order vibration system is firstly derived. The compensation and disturbance torques are determined according to practical engineering. The criteria for designing the optimal compensations are based on the analytical and simulation results. Then, the criteria are applied to a flexible spacecraft actuated by constant control torque in the presence of sustained periodic disturbance. The optimal compensation torque parameters for spacecraft are acquired based on former criteria. The compensate effectiveness of the optimal compensation torque is provided and compared with results of other selections in the frequency and amplitude ratio domain. Numerical simulation results and experimental results clearly demonstrate the good performance of proposed criteria. This work provides a significant reference for the vibration attenuation of meteorological satellites in the present of periodic disturbance.

Examination and implementation for direct torque controlled permanent magnet synchronous motor with space vector modulation

This study investigates the direct torque control strategy of permanent magnet synchronous motor with the space vector modulation, on account of large torque fluctuation and varied switching frequency of classic direct torque control strategy. The relationship among the terminal control voltages and the torque and stator flux of the permanent magnet synchronous motor is derived through the dynamic model of motor. Accordingly, the torque and the flux closed-loop feedback control structure are established, where the error signals are regulated by the proportional and integral controllers to generate output voltages. Furthermore, the parameters of the controllers are designed through explicitly analyzing the frequency domain models of the torque control loop and the flux control loop. The accurate calculation formula of control parameters, which has both explicit setting target and definite physical meaning, is obtained. Therefore, the design of torque and flux controller parameters becomes easy in the direct torque control with space vector modulation technology, and satisfactory flux and torque control can be acquired. Finally, simulation and experimental tests are demonstrated in support of the validity of the investigated scheme and the feasibility of the proposed controller parameter design.

Three-dimensional CFD simulation of the load rejection transient process considering regulating system

Both the flow patterns in hydraulic turbine and the governor regulating system of turbine-generator unit have great influence on the operation stability of units, but they were treated separately in previous studies. In this paper, the equation for regulating system is cooperated into the three-dimensional (3D) computational fluid dynamics (CFD) model of a hydraulic turbine, for attempting the simulation of the small disturbance transient processes in hydropower plants. The 15% load rejection transient process for a model pumped-storage system with a low specific-speed pump turbine is successfully simulated; reasonable torque, speed and other macro parameters are provided; the flow patterns inside the runner are analysed. The results show that the regulation characteristics of the small fluctuation are acceptable and accordant with practical experience, with the stability guaranteed and the attenuation of fluctuating parameters obvious. These verify the feasibility of using 3D CFD to simulate the load rejection transient process, and lay a foundation for further studying the starting stability of units.

One-dimensional univariate work simulation of turbocharged engine with restrictor before compressor inlet

All over the world, and in Russia, especially, the engineering sports competitions "Formula Student" are gaining popularity. Formula Student - is an international competition held among students of technical universities, in order to get practical knowledge in the process of developing and building a Formula student class racecar. When creating a car, you must adhere to strict technical regulations. So, one of the limitations is the maximum engine capacity - 710 cubic meters, which, in itself, implies the use of a motorcycle engine. A mandatory condition is the presence of a restrictive nozzle (restrictor) which have 20 mm diameter and placing in the inlet system. This causes many problems when designing engine intake systems. However, it allowed using various systems of pressurization of engines. The most common and effective is the installation of the turbocharger. This helps to solve the problem of insufficient amount of air that entering to the engine. Moreover, with the correct configuration of all components of the intake system in combination with the turbocharger, it is possible to achieve power and torque exceeding the standard engine without a restrictive nozzle. The article presents the data obtained in the course of a one-dimensional simulation of the KTM LC4 engine with a turbocharger and a restrictor in the intake manifold. The purpose of the work is to reduce the negative influence of the restrictor on the power and torque parameters of the KTM LC4 engine by using a turbocharger. In the course of the work, an analysis was made of gas-dynamic processes occurring in various parts of the engine intake system that affect its output values based on numerical studies. Because of the research, the dependences of the output parameters of the engine (maximum power and maximum torque) on the parameters, shapes and sizes of various components of the intake system with a turbocharger.

Probabilistic bolt load distribution analysis of composite single-lap multi-bolt joints considering random bolt-hole clearances and tightening torques

This paper presents a stochastic bolt load distribution analysis method of composite single-lap multi-bolt joints by using an improved three-stage spring-based method and Monte Carlo simulation. In the proposed method, the random properties of tightening torque, bolt-hole clearance, lamina properties and geometric parameters were involved. The allowable manufacturing tolerance band of parameters and clearance fit were considered, and a combining distribution function consisting of binomial distribution and normal distribution function was adopted for modeling the random tightening torque relaxation. To validate the proposed method, a set of composite single-lap three-bolt joints were designed and tested to achieve the stochastic bolt load distribution of the joint. Good agreements between the numerical and experimental stochastic bolt load distribution validated the proposed method. Furthermore, the probabilistic bolt load distributions of the three-bolt joints in four tightening torque conditions, including finger-tight, wrench torque, standard tightening torque and relaxation tightening torque, were investigated. It is found that tightening torque conditions and bolt-hole clearances have significant influences on the variation of the bolt load distribution, while the effects of other random parameters on the variation of the bolt load distribution are slight.

Correlation of upper limb joint load withsimultaneous throwing mechanics including acceleration parameters in amateur baseball pitchers.

[Purpose] The purpose of this study was to provide information regarding the knowledge of mechanical principles related to the load applied to the shoulder and elbow during the pitching motion. [Subjects and Methods] The three-dimensional kinematics of body segments were measured in 19 amateur baseball players with a VICON motion capture system. The correlation between maximum shoulder internal torque, maximum elbow varus torque, and simultaneous kinematic parameters including joint angular acceleration and ball acceleration was investigated. [Results] Peak shoulder internal rotation torque and elbow varus torque averaged 31 Nm and 26 Nm, respectively. Ball acceleration had the strongest influence on shoulder internal rotational torque (standardized partial regression coefficient 0.69). During previous maximum external rotation (pre-MER), the main cause parameter of elbow varus torque was shoulder horizontal adduction velocity (r=0.672). On the other hand, after MER (post-MER), the main cause was ball acceleration (r=0.745). [Conclusion] Results of our study suggest that one of the main mechanical principles of joint load during the baseball pitching motion may be the ‘inertia’ yielded on the segment distal to the certain joint.

Research on Anti-saturation Feedback Control Method for UAV Avionics System

UAV avionics system is prone to saturation distortion under unsteady conditions, so anti-saturation control is needed. A control method of UAV avionics system based on anti-saturation feedback compensation is proposed. The anti-saturation control process of UAV avionics system is a multi-objective optimization process with multi-variables. The constrained parameter model of UAV avionics system control is constructed. Electromagnetic loss, torque, output power and other parameters are taken as constraint indexes, the original control information of UAV avionics system is treated with self-stabilization, the equivalent control circuit is designed, and the magnetic resonance transmission mode of avionics system is analyzed. An anti-saturation feedback tracking control method is used for steady-state control of the output voltage of the avionics system. The error compensation function is constructed to adjust the output adaptive parameters of the avionics system and the static anti-saturation compensator is constructed to compensate the power gain. The yaw error and the output steady-state error of the avionics system are reduced. The simulation results show that the proposed method has better output stability, lower output error, better real-time performance and better linear auto-disturbance rejection control performance.

Generalized Proportional Integral Observer-Based Robust Finite Control Set Predictive Current Control for Induction Motor Systems with Time-Varying Disturbances

During the past few years, finite control set predictive current control (PCC) method has attracted more and more attention in research and industry applications. However, PCC method could be improved by considering two points. First, the current reference used in the cost function of PCC control scheme is usually produced by a proportional and integration speed controller. Confront with load torque and time-varying system parameters, it is a better solution to design a disturbance estimation based feed-forward compensated controller. In this way, the current reference could be generated faster and more accurate. Second, the PCC method is model-based method which means the accuracy of the model parameters are essential. In real system, time-varying parameters existed almost always. This paper investigates a generalized proportional integral observer based PCC approach for dealing with load torque disturbance, time-varying parameter uncertainties. The effectiveness of the proposed method has also been confirmed by simulation and a lab-constructed experimental prototype.

Influence of Drilling Parameters on Torque during Drilling of GFRP Composites Using Response Surface Methodology

Polymer based composites have marked their valuable presence in the area of aerospace, defense and automotive industry. Components made of composite, are assembled to main structure by fastener, which require accurate, precise high quality holes to be drilled. Drilling the hole in composite with accuracy require control over various processes parameters viz., speed, feed, drill bit size and thickens of specimen. TRIAC VMC machining center is used to drill the hole and to relate the cutting and machining parameters on the torque. MINITAB 14 software is used to analyze the collected data. As a function of cutting and specimen parameters this method could be useful for predicting torque parameters. The purpose of this work is to investigate the effect of drilling parameters to get low torque value. Results show that thickness of specimen and drill bit size are significant parameters influencing the torque and spindle speed and feed rate have least influence and overlaid plot indicates a feasible and low region of torque is observed for medium to large sized drill bits for the range of spindle speed selected. Response surface contour plots indicate the sensitivity of the drill size and specimen thickness to the torque.

Assessment of Elbow Torque and Other Parameters During the Pitching Motion: Comparison of Fastball, Curveball, and Change-up

To assess the precision of a new wearable device in detecting medial elbow torque during the pitching motion in competitive baseball pitchers and to determine the differences in torque across pitch types and thrower demographic characteristics. High school and collegiate baseball pitchers were recruited from August 1, 2016, to January 31, 2017, through direct request by athletic trainers and coaches. Body dimensions and throwing arm measurements of the participants were collected. The sensor was positioned directly over the medial elbow and pitchers were instructed to throw 8 fastballs, 8 curveballs, and 8 change-ups in a standard, randomized sequence. The sensor reported elbow torque, arm speed, arm slot, and shoulder rotation, whereas a radar gun measured peak ball velocity. Precision was calculated by measuring outlier rate, and mixed model regression analysis was performed to detect differences in throwing biomechanics among pitch types. In total, 37 competitive baseball pitchers were included in the study. The device had a precision of 96.9% for fastballs, 96.9% for curveballs, and 97.9% for change-ups. The device was sensitive enough to distinguish pitches according to elbow torque, arm speed, arm slot, and shoulder rotation. Fastballs caused the greatest relative torque across the medial elbow (average= 45.56Nm), compared with change-ups (43.77Nm; P= .006) and curveballs (43.83Nm; P= .01). Ball velocity contributed most to medial elbow torque (P= .003), followed by elbow circumference (P= .021), where smaller elbow circumference predicted greater medial elbow torque. The sensor is a precise and reproducible device for measuring torque across the medial elbow, as well as additional parameters of arm speed, arm slot, and shoulder rotation. Torque was significantly relatively higher in fastballs than curveballs and change-ups. Level III, comparative study.

Modeling and simulation of longitudinal dynamics coupled with clutch engagement dynamics for ground vehicles

During the engagement of the dry clutch in automotive transmissions, clutch judder may occur. Vehicle suspension and engine mounts couple the torsional and longitudinal models, leading to oscillations of the vehicle body that are perceived by the driver as poor driving quality. This paper presents an effective formulation for the modeling and simulation of longitudinal dynamics and powertrain torsional dynamics of the vehicle based on non-smooth dynamics of multibody systems. In doing so friction forces between wheels and the road surface are modeled along with friction torque in the clutch using Coulomb’s friction law. First, bilateral constraint equations of the system are derived in Cartesian coordinates and the dynamical equations of the system are developed using the Lagrange multiplier technique. Complementary formulations are proposed to determine the state transitions from stick to slip between wheels and road surface and from the clutch. An event-driven scheme is used to represent state transition problem, which is solved as a linear complementarity problem (LCP), with Baumgarte’s stabilization method applied to reduce constraint drift. Finally, the numerical results demonstrate that the modeling technique is effective in simulating the vehicle dynamics. Using this method stick-slip transitions between driving wheel and the road surface and from the clutch, as a form of clutch judder, are demonstrated to occur periodically for certain values of the parameters of input torque from engine, and static and dynamic friction characteristics of tire/ground contact patch and clutch discs.

Neuromuscular recovery in ACL reconstruction with Bone-Tendon-Patellar-Bone and Semitendinosus-Gracilis autograft.

Several different types of grafts have been used in ACL rupture. The purpose of the study was to compare the recovery of lower limbs muscle strength and proprioception in athletes, who underwent ACL reconstruction with Bone-Patellar-Tendon-Bone (BPTB) versus semitendinosus and gracilis(HS) autografts. We enrolled 30 male amateur athletes. Each patient was evaluated by isokinetic test, triaxial accelerometer test and balance test with stabilometric platform. Isokinetic test evaluated quadriceps and hamstrings Peak Torque. Accelerometer test evaluated squat jump test (SJT) and stiffness test (ST). The recording on the balance platform was performed with open and closed eyes and evaluated medio-lateral and anterior-posterior pathways. 30 patients were selected (15 in group BPTB and 15 in group HS). In SJT we noticed a statistically significant difference in height of jump in the involved side in favour of Group BPTB (p=0.037) and not significant difference in the other parameters. In the ST, we did not observe significant statistical differences in the parameters of the test. The stabilometric platform data and isokinetic peak torque parameters did not show a significant difference. Little high quality researches are available to help determine when patients can safely return to full activity and sport. Included evaluation criteria were a combination of factors regarding knee motion, muscles strength and neuromuscular function. In our study, despite a not full recovery of explosive strength in HS group , the balance and the other parameters after one year are comparable between the two graft. In our findings there isn't clinical difference between the two grafts. We suggest that the evaluation of explosive strength and proprioception are the priority parameters in neuromuscular recovery after ACL reconstruction.

Design and Implementation of Disturbance Compensation-Based Enhanced Robust Finite Control Set Predictive Torque Control for Induction Motor Systems

Finite-control-set-based predictive torque control (PTC) method has received more and more attention in recent years due to its fast torque response. However, it also has two drawbacks that could be improved. First, the torque reference in the cost function of the existing PTC method is generated by the proportional-integral speed controller, so torque reference's generation rate is not fast and its accuracy is low especially when the load torque is given suddenly and inertia value is varying. In addition, the variable prediction of the traditional PTC method depends on the system model, which also has the problem of parameter uncertainties. This paper investigates a disturbance observer (DOB)-based PTC approach for induction motor systems subject to load torque disturbances, parameter uncertainties, and time delays. Not only does the speed loop adopt a DOB-based feed-forward compensation method for improving the system disturbance rejection ability and robustness, but the flux, current, and torque predictions are also improved by using this technique. The simulation and experimental results verified the effectiveness of the proposed method.

Robust control of mode transition for a single-motor full hybrid electric vehicle

The single-motor full hybrid electric vehicle tends to suffer drivability and excessive clutch wear issues during the mode transition from electric driving to hybrid driving because the single motor must simultaneously propel the vehicle and divert torque via clutch engagement to start the engine. In this study, a novel four-phase compound robust control method consisting of the feedforward–feedback technology and the robust compensation approach is proposed to address these problems during the mode transition. The whole mode transition process was divided into four consecutive phases according to the operating status of engine and clutch. In each phase, a nominal controller based on the feedforward–linear quadratic regulator feedback technology is first designed for the nominal linear model to guarantee a desired control performance. And then, the nonlinear uncertain part of the engine/clutch torque and the vehicle resistant torque as well as the model parameter uncertainties are all considered as equivalent disturbances, and a robust compensator is introduced to suppress the effect of equivalent disturbances. Simulation is performed to validate the effectiveness of the proposed control method. The results show that the four-phase compound robust control method can achieve better vehicle drivability and minimize clutch wear during the mode transition from electric driving to hybrid driving even in the presence of various torque disturbances and parameter uncertainties.

Effects of Mat Pilates on hip and knee isokinetic torque parameters in elderly women

This study aimed to analyze the effects of Mat Pilates on isokinetic torque of the lower limbs in elderly women. Fourteen elderly women (Age 62 ± 3 yr) participated in 12 weeks of Mat Pilates training (60-min sessions, 3 times per week). Repetitions increased every 4 weeks and the difficulty of exercises progressed from beginner to intermediate and advanced. Peak torque was assessed before (week ‐4 and week 0, considered as a control period) and after 6 and 12 weeks of a periodized Mat Pilates intervention. The results showed significant improvements (p < 0.05) in concentric and eccentric peak torque of knee flexors muscles, hip flexor and extensor muscles after 12 weeks. Mechanical work showed significant improvement (p < 0.05) for knee extensor muscles during eccentric contractions after week 12, for hip extensor muscles during concentric contractions week 12, and for flexor muscles during concentric and eccentric contractions after week 12. We conclude that the periodization of Mat Pilates induced significant improvements in multiple isokinetic torque parameters.

A 3-axis torsion quasi-zero-stiffness-based sensor system for angular vibration measurement

In this paper, a novel 3-axis torsion quasi-zero-stiffness (TQZS)-based sensor system is proposed for absolute rotation measurement in vibration systems. Analysis on the applied torque and structural parameters shows that the proposed mechanism with two concentric spheres connected by six symmetry distributed springs could approximately achieve TQZS features in three rotational degrees of freedom simultaneously, thus a remarkable torsional vibration measurement performance can be guaranteed. Although due to high stiffness, the mechanism also has high anti-interference ability about force or vibration in translational directions. Mathematical modeling and numerical simulations are carried out to show the effectiveness of the proposed 3-axis sensor system in different base vibrations. In consideration of its feasibility and high performance, it can be foreseen that the proposed TQZS-based sensor will get more and more implementations in various engineering practices with torsional vibration measurements.

The magnetic driver in rotating wave energy converters

In rotating wave energy converters, the traditional contact seal cannot completely prevent water leakage problems. In this study, the magnetic driver was introduced to replace the traditional contact seal in rotating wave energy converters, aiming to achieve absolute waterproof sealing and long-term running of the equipment. The equivalent magnetic charge theory and the finite element method were adopted to analyze the influence of magnetic driver parameters on its transmitted torque. The correlations between transmitted torque and different parameters were deduced from theoretical calculations and simulation results. The magnetic driver serves to improve the performance of transmission mechanism and promote the development of rotating wave energy converters, and the outcome of this research will guide the design of magnetic drivers suitable for rotating wave energy converters.

Multilevel inverter with space vector modulation: intelligence direct torque control of induction motor

An Intelligence direct torque control (DTC) of induction motor using multilevel inverter with space vector modulation (SVM) is proposed in this study. The novelty of the proposed intelligence technique is an artificial neural network (ANN), which is utilised for the DTC of the induction motor. Here, ANN has been trained by using the target parameters such as reference quadrature and direct axis voltage with the corresponding input parameters change in motor torque and flux. The change in motor torque and flux parameters are identified by using the multilevel inverter output voltage and current. The back propagation process is used for the training process of the ANN. By using the ANN outputs, the SVM technique develops the control pulses for the multilevel inverter. Then the proposed intelligence technique is implemented in the MATLAB/simulink platform and the effectiveness is analysed by comparing with the different case studies and different methods. The comparison results demonstrate the superiority of the proposed approach and confirm its potential to solve the problem.