Torque Parameters Research Articles

Nonholonomic dynamics of drill string bit whirling in a deep bore-hole

This article studies the problem of wirl vibrations of a rotating drill string bit under conditions of its friction interaction with the bore-hole bottom surface at the wandering contact point. The mechanism of the bit spinning and rolling without sliding on the rigid surface has been analyzed. To study the wirl vibrations, the methods of nonholonomic mechanics are used. As an example, spherical bit whirling on spherical bore-hole bottom is considered. The kinematic inducement of the rotating bit motion without sliding is shown to be the main cause of its stability loss. The detailed study of the bit whirling revealed three types of its stable and unstable motions associated with direct and inverse rolling as well as pure spinning. It is found that the most detectable influence on dynamics of the system and its stability is exerted by the overall stiffness of the drill string tube, which depends on parameters of compressive axial force and torque and diminishes as their critical values are approached.

Time Course of Neuromuscular Adaptations to Knee Extensor Eccentric Training

This study investigated the chronology of neural and morphological adaptations to knee extensor eccentric training and their contribution to strength gains in isometric, concentric and eccentric muscle actions. 20 male healthy subjects performed a 12-week eccentric training program on an isokinetic dynamometer, and neuromuscular evaluations of knee extensors were performed every 4 weeks. After 12 training weeks, significant increases were observed for: isometric (24%), concentric (15%) and eccentric (29%) torques; isometric (29%) and eccentric (33%) electromyographic activity; muscle thickness (10%) and anatomical cross-sectional area (19%). Eccentric and isometric torques increased progressively until the end of the program. Concentric torque and muscle mass parameters increased until the eighth training week, but did not change from this point to the twelfth training week. Eccentric and isometric activation increased at 4 and 8 training weeks, respectively, while no change was found in concentric activation. These results suggest that: 1) the relative increment in concentric strength was minor and does not relate to neural effects; 2) eccentric and isometric strength gains up to 8 training weeks are explained by the increased neural activation and muscle mass, whereas the increments in the last 4 training weeks seem to be associated with other mechanisms.

Possibility of intrinsic muscle contractile properties in force summation and postactivation potentiation as indices of maximal muscle strength and muscle fatigue

We investigated whether intrinsic muscle contractile properties in force summation and postactivation potentiation (PAP) can be used as indices of maximal muscle strength and muscle fatigue. Twelve men participated in this study. The maximum voluntary contraction torque (MVC), torque evoked by several stimulations in the tibialis anterior (TA) muscle, force summation parameters, and PAP were evaluated with the progression of fatigue. The force summation parameters were evaluated with respect to responses of single, double, and triple stimulations. The percent decreases in the evoked torque parameters with or without PAP were greater than those during MVC. Force summation parameters were significantly related to MVC and fatigue resistance. Intrinsic muscle contractile properties with or without PAP in the TA overestimate fatigue during MVC. However, force summation parameters can be used as indices of maximal muscle strength with or without fatigue and fatigue resistance capacity.

An Improved Torque Feed-forward Control with Observer-based Inertia Identification in PMSM Drives

This paper is concerned with speed tracking control problem for permanent-magnet synchronous drives (PMSM) in the presence of an variable load torque and unknown model parameters. The disturbance of speed control caused by inaccuracy of model parameters has been investigated. A load torque observer has been proposed to observe the load torque and estimate the disturbance caused by inaccuracy of model parameters. Both inertia and friction coefficient are identified in gradient descent approach. The stability condition of the observer has also been studied. Furthermore an improved feed-forward control has been introduced to reduce the speed track error. The proposed control strategy has been verified by both simulation and experimental results

High Dynamic Performance of Interior Permanent Magnet Synchronous Motor Drives Based on Feed-forward Load Torque Compensator

This article presents an improvement in the dynamic performance of interior permanent magnet synchronous motor drives by using a feed-forward load torque compensator along with a proportional-integral speed controller. In such a case, the load torque estimator compensates the speed control by setting a feed-forward torque value through the q-axis current reference value, so that the machine speed can reach the reference speed very fast. The experimental and simulation results indicate that the proposed control technique improves the interior permanent magnet synchronous motor speed performance in terms of tracking precision and travel time. Moreover, the performance of an interior permanent magnet synchronous motor drive system using a conventional proportional-integral controller is compared with the proposed controller. The results show that the proposed proportional-integral controller with a feed-forward load torque compensator has achieved superior performance compared to those of the conventional one. An acceptable speed response under load torque variations and parameter uncertainty is found.

Patientenzufriedenheit und Muskelkraft nach Knietotalendoprothese in Abhängigkeit vom Body-Mass-Index

In a monocentric study, we investigated patient satisfaction, clinical outcome and isokinetic muscle torque in dependence on the body mass index (BMI) in the mid-term outcome after total knee arthroplasty. A group-matched study with two groups (each 40 knee arthroplasties in 40 patients) with a normal body mass index (BMI 20-25) and above 25 was conducted. The groups were matched for sex, diagnosis and age. Satisfaction, HSS score and isokinetic torque parameters with the Cybex 340 system were measured. There were no differences in the demographic data except for BMI. The HSS score was significantly lower in the overweight group (p = 0.04). Also there were more patients with an HSS score below 60 (bad result) in the group with the higher BMI (0 vs. 9, p = 0.002). Only one patient was not satisfied in the normal weight group, whereas 9 patients in the group BMI > 25 were not satisfied (p = 0.014). No differences between the groups could be found in maximum torque, work and power. The patient satisfaction was much lower in patients with BMI higher than 25. There were no differences between the groups in isokinetic torque parameters.

Plasma Treatment Maintains Surface Energy of the Implant Surface and Enhances Osseointegration

The surface energy of the implant surface has an impact on osseointegration. In this study, 2 surfaces: nonwashed resorbable blasting media (NWRBM; control) and Ar-based nonthermal plasma 30 days (Plasma 30 days; experimental), were investigated with a focus on the surface energy. The surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and the chemistry by X-ray photoelectron spectroscopy (XPS). Five adult beagle dogs received 8 implants (n = 2 per surface, per tibia). After 2 weeks, the animals were euthanized, and half of the implants (n = 20) were removal torqued and the other half were histologically processed (n = 20). The bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated on the histologic sections. The XPS analysis showed peaks of C, Ca, O, and P for the control and experimental surfaces. While no significant difference was observed for BIC parameter (P > 0.75), a higher level for torque (P < 0.02) and BAFO parameter (P < 0.01) was observed for the experimental group. The surface elemental chemistry was modified by the plasma and lasted for 30 days after treatment resulting in improved biomechanical fixation and bone formation at 2 weeks compared to the control group.

Deadbeat direct torque control for permanent magnet synchronous motors using particle swarm optimisation

A robust torque, flux and speed controllers design method for Permanent Magnet Synchronous Motor (PMSM) drive is introduced in this paper. A simple algorithm is illustrated to adjust the parameters of torque, flux and speed controllers. This mini–max optimisation problem is solved using Particle Swarm Optimisation approach (PSO). The solution thus attained is global optimal and robust. The proposed technique discards common problems in conventional Direct Torque Control (DTC) including; torque ripples, resistance change effect, low speed and integration drift. Also it is represented by fast tracking capability, deadbeat responses, and robust to load disturbances and low speed operation. Simulation and experimental results verify the expediency and viability of the proposed technique.

Robust nonlinear receding-horizon control of induction motors

Nonlinear robust receding-horizon control is designed and applied to fifth-order model of induction motor in cascade structure. The controller is based on a finite horizon continuous time minimization of the predicted tracking errors and no online optimization is needed. The initial system is decomposed into two sub-systems (mechanical and electromagnetic sub-systems) in cascade form. An integral action is incorporated in external loop to increase the robustness of the controller with respect to unknown time-varying load torque and mechanical parameters uncertainties. The control uses only measurement of the rotor speed and stator currents. The rotor flux is estimated by Kalman filter. The proposed nonlinear controller permits to achieve asymptotic speed and flux tracking in presence of mechanical parameters uncertainties, unknown variable load torque and resistances variations. In addition, it assures asymptotic decoupling of the speed and flux subsystems. The controller is applied, via simulation, to a benchmark example.

The effects of triceps surae fatigue on the torque and electromyographic parameters in athletes compared with non-athletes

The common description of muscular fatigue is the failure of muscle in maintaining a target force. Even in sustained contraction, when muscle force is held at a stable level, physiological, biomechanical and electromyographic changes can occur. The purpose of this study is to compare the effects of triceps surae (TS) fatigue on the torque, falling slope and electromyographic (EMG) parameters between athletes and non-athletes. Nineteen healthy women (10 non-athletes and 9 basketball players) participated in this study. After warm-up, subjects performed one maximum voluntary contraction (MVC) followed by fatigue test including sustained maximum isometric contraction of TS until the peak torque (PT) decreased to 50% of maximum value. Immediately after the test, subjects were asked to perform one MVC; then, root mean square (RMS), median frequency (MDF), median frequency slope (MDF slope), PT, falling slope (FSL) and the amount of pain were measured. In both groups shift of MDF slope to negative values, significant decrease of MDF and RMS occurred at the end of the fatigue test (P < 0.05). Immediately after the test, PT decreased significantly in both groups (P < 0.05), however, decrease of FSL was significant in non-athletes (P < 0.05) but not in athletes. After fatigue test, increase in Pain was significant in both groups (P < 0.05). Before fatigue test, at the end, and immediately after the test, MDF of non-athletes was more than athletes. There was no significant difference in RMS between the two groups. Our findings suggest that TS fatigue affects EMG parameters, PT and pain in athletes and non-athletes similarly.

Torque value evaluated by ultrasonic technique during polymer melting process

The torque profile during the melting process of low-density polyethylene (LDPE) pellets in an internal mixer has been estimated by ultrasound. Improved factor analysis was utilized to evaluate the relationship between torque and ultrasonic parameters and to rebuild the torque profile. The estimated torque value had an agreement with the measured data within 11%, which means that the presented ultrasonic measurement contained the same information as the torque measurement, namely viscosity. Therefore, the presented ultrasonic technique and evaluating method might be an optional approach to diagnose the melting process of polymer in the internal mixer and estimate the torque profile.

Fractional-Slot Concentrated-Winding Axial-Flux Permanent-Magnet Machine With Core-Wound Coils

This paper presents the design, finite-element analysis (FEA), and experimental verification of a single-stator double-rotor fractional-slot concentrated-winding axial-flux permanent-magnet machine with core-wound coils. The advantages that are obtained by adopting such coil construction in terms of shorter end-winding connections higher fill factor, and mechanical robustness of the magnetic structure are highlighted. Machine performances both at no load and at rated load are analyzed through static FEA, and a simple index is introduced to compare induced losses in the permanent magnets for various machine configurations. Time-stepped transient FEA is used to validate the index. The construction and experimental testing of a full-scale prototype is described to confirm the expected performances and to characterize the prototype in terms of losses (both at no-load and in loaded conditions), cogging torque, and main machine parameters.

Direct dynamic imaging of non-adiabatic spin torque effects

Spin-transfer torques offer great promise for the development of spin-based devices. The effects of spin-transfer torques are typically analysed in terms of adiabatic and non-adiabatic contributions. Currently, a comprehensive interpretation of the non-adiabatic term remains elusive, with suggestions that it may arise from universal effects related to dissipation processes in spin dynamics, while other studies indicate a strong influence from the symmetry of magnetization gradients. Here we show that enhanced magnetic imaging under dynamic excitation can be used to differentiate between non-adiabatic spin-torque and extraneous influences. We combine Lorentz microscopy with gigahertz excitations to map the orbit of a magnetic vortex core with <5 nm resolution. Imaging of the gyrotropic motion reveals subtle changes in the ellipticity, amplitude and tilt of the orbit as the vortex is driven through resonance, providing a robust method to determine the non-adiabatic spin torque parameter β=0.15±0.02 with unprecedented precision, independent of external effects.

First-principles calculation of the nonadiabatic spin transfer torque in Ni and Fe

The magnetization dynamics of a ferromagnet subjected to an electrical current are described by an extension of the Landau-Lifshitz-Gilbert equation that contains two additional terms, the adiabatic and nonadiabatic spin-transfer torques. First-principles calculations of the nonadiabatic spin-transfer torque parameter $\ensuremath{\beta}$ for bcc iron and fcc nickel show that $\ensuremath{\beta}$ is related to and typically of the same order as $\ensuremath{\alpha}$, the damping constant, but is distinct from it. Calculations as a function of the ratio of spin-dependent scattering rates show that (1) the minimum of the damping constant as a function of scattering rate does not change significantly, and (2) when the polarization of the current approaches zero, $\ensuremath{\beta}$ can become large but the implied domain-wall velocity does not.

Poor Information Analysis of Rolling Bearing Friction Torque Characteristic Parameter Based on Phase Space

The friction torque of rolling bearings belongs to an information poor system with unknown probability distributions and trends. This counteracts dynamical assessment for the characteristics of the rolling bearing friction torque as a time series. For this reason, the chaos theory is employed to recover the original dynamic characteristics of a friction torque time series by means of the phase space reconstruction theory. The dynamical Bayesian probability density function of the characteristic parameters of the friction torque is constructed by the information poor theory based on the phase space. The method for point estimation, interval estimation, and trend estimation of the characteristic parameters is proposed in this paper. The investigation shows that the error between the calculated result and the experimental result is very small.

Isokinetic Knee Joint Evaluation in Track and Field Events

The purpose of this study was to evaluate maximal torque of the knee flexors and extensors, flexor/extensor ratios, and maximal torque differences between the 2 lower extremities in young track and field athletes. Forty male track and field athletes 13-17 years old and 20 male nonathletes of the same age participated in the study. Athletes were divided into 4 groups according to their age and event (12 runners and 10 jumpers 13-15 years old, 12 runners and 6 jumpers 16-17 years old) and nonathletes into 2 groups of the same age. Maximal torque evaluation of knee flexors and extensors was performed on an isokinetic dynamometer at 60°·s(-1). At the age of 16-17 years, jumpers exhibited higher strength values at extension than did runners and nonathletes, whereas at the age of 13-15 years, no significant differences were found between events. Younger athletes were weaker than older athletes at flexion. Runners and jumpers were stronger than nonathletes in all relative peak torque parameters. Nonathletes exhibited a higher flexor/extensor ratio compared with runners and jumpers. Strength imbalance in athletes was found between the 2 lower extremities in knee flexors and extensors and also at flexor/extensor ratio of the same extremity. Young track and field athletes exhibit strength imbalances that could reduce their athletic performance, and specific strength training for the weak extremity may be needed.

Age-related changes in cardio-respiratory responses and muscular performance following an Olympic triathlon in well-trained triathletes

The aim of the present study was to compare the maximal isometric torque and cardio-respiratory parameters in well-trained young and master triathletes prior to and following an Olympic distance triathlon. One day before and 24 h following the event, participants performed three maximum voluntary isometric knee extensions and flexions and an incremental running test on a treadmill to determine the maximal isometric torque, maximal oxygen uptake VO(2max), speed at VO(2max) (vVO(2)max), speed at ventilatory thresholds (VT1 and VT2) and submaximal running economy. Prior to the event VO(2max), vVO(2)max, speed at ventilatory thresholds and running economy were significantly lower in master athletes, but maximal voluntary torque was similar between the groups. 24 h following the race, a similar significant decrease in VO(2max) (-3.1% in masters, and -6.2% in young, p < 0.05), and vVO(2)max (-9.5% in masters, and -5.6% in young, p < 0.05) was observed in both the groups. The speed at VT2 significantly decreased only in master athletes (-8.3%, p < 0.05), while no change was recorded in maximal voluntary torque or submaximal running economy following the event. The results indicate that for well-trained subjects, the overall relative exercise intensity during an Olympic distance triathlon and the fatigue 24 h following the event seem to be independent of age.

Energy-Efficient of Non-Invasive Motor for On-Line Monitoring System Based on Reasoning Model

This paper mainly introduces the development process of energy-efficient of non-invasive motor for on-line monitoring system based on reasoning model. In addition, the function , composition and commissioning of shis system is introduced. In this system, in order to collect and analyze status recording of the motor running, operating parameters of motor speed, torque and power factor, efficiency are estimated on-line by using motor stator current signal feature analysis technology. In the paper, air-gap torque method is used to non-invasive electromotor for efficiency computation. The designing process of software for On-line monitoring system is shown as: Firstly, monitor motor’s operating parameters on-line, then, motor energy management is supported by the analysis of monitoring recording. At the same time, construct communication network for motor monitoring by using wireless communication technology about efficiency curve of industry motor. This system has the advantages of monitoring precision, easy installation, low costs, especially suitable for monitoring and energy management of efficiency for small and medium-sized motor, and it has been used widely in industrial production.

Self organizing fuzzy sliding mode controller for the position control of a permanent magnet synchronous motor drive

In this paper, a self organizing fuzzy sliding mode controller (SOFSMC) which emulates the fuzzy controller with gain auto-tuning is proposed for a permanent magnet synchronous motor (PMSM) drive. The proposed controller is used for the position control of the PMSM drive. The performance and robustness of the control system is tested for nonlinear motor load torque disturbance and parameter variations. It has a novel gain self organizing strategy in response to the transient or tracking responses requirement. To illustrate the performance of the proposed controller, the simulation studies are presented separately for the SOFSMC and the fuzzy controller with gain auto-tuning. The results are compared with each other and discussed in detail. Simulation results showing the effectiveness of the proposed control system are confirmed under the different position changes.

The usage of CAN-Bus messages for engine power determination

Determination of the actual power of tractor's engine in the operation can be done by calculation which requires the use of a range of parameters such as coefficient of rolling resistance, mechanical efficiency, the moments of inertia, etc. Their values are usually tabulated and therefore the engine power cannot be determine without simplifying. Another solution is to use the actual engine torque message from the CAN-Bus, which brings a specific value of the actual torque. The aim is to use the current torque to calculate the engine power in the deployment of tractor's set in transport operation. The results show that at a uniform movement of the flat section the engine power reached 73 kW. When driving uphill, the value of the actual power reached from 130 to 150 kW depending on the selected gear. Using the actual parameters of torque makes possible to identify the known full speed characteristics of the current engine without the need for assembly demanding measurement techniques.