Torque Transducer Research Articles

Biomechanical loading on the upper extremity increases from single key tapping to directional tapping

Musculoskeletal disorders associated with computer use span the joints of the upper extremity. Computing typically involves tapping in multiple directions. Thus, we sought to describe the loading on the finger, wrist, elbow and shoulder joints in terms of kinematic and kinetic difference across single key switch tapping to directional tapping on multiple keys. An experiment with repeated measures design was conducted. Six subjects tapped with their right index finger on a stand-alone number keypad placed horizontally in three conditions: (1) on single key switch (the number key 5); (2) left and right on number key 4 and 6; (3) top and bottom on number key 8 and 2. A force–torque transducer underneath the keypad measured the fingertip force. An active-marker infrared motion analysis system measured the kinematics of the fingertip, hand, forearm, upper arm and torso. Joint moments for the metacarpophalangeal, wrist, elbow, and shoulder joints were estimated using inverse dynamics. Tapping in the top–bottom orientation introduced the largest biomechanical loading on the upper extremity especially for the proximal joint, followed by tapping in the left–right orientation, and the lowest loading was observed during single key switch tapping. Directional tapping on average increased the fingertip force, joint excursion, and peak-to-peak joint torque by 45%, 190% and 55%, respectively. Identifying the biomechanical loading patterns associated with these fundamental movements of keying improves the understanding of the risks of upper extremity musculoskeletal disorders for computer keyboard users.

Stability Studies of Torque Transducers

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Measurement of torsional moment: new standards open the path of innovation

The contemporary state of the very important field of torque measurement is considered. A description and results of studying a model device TSM/01 for reproducing torque are provided. On the basis of operation of this device there is a method for comparing measurements results for a reference torque transducer that is part of the TSM/01 and a verified (calibrated) transducer.

Detection of Precursors to Component Failure in a Spur Gear Drive-Train by Means of a Torque Transducer

In the wind energy industry, gearbox failures are among the most costly and the most frequent, adding significantly to the operation and maintenance costs over the life cycle of the turbine. Despite significant improvements in the understanding of gear loads and dynamics, even to the point of establishing international standards for design and specifications of wind turbine gearboxes, these components generally fall short of reaching their 20 year design life. In a significant number of gearbox failures, the primary bearing on the low speed shaft experiences faults in its operation, such as misalignment and movement on the mounts. To investigate the topic of gear health management, a fault detection approach is applied to a test bed involving a spur gear double-reduction transmission, outfitted with a torque transducer and triaxial accelerometers on the bearing cases. The test bed is not a wind turbine gearbox – the gear arrangement is different and the gears are smaller compared to that of a typical wind turbine gearbox – but it does serve to test the modeling and fault detection methods proposed in this paper. Both baseline and faulted measurements are taken from the experimental set-up for data analysis. It is shown that the torque sensor provides an early indication of fault precursors, such as misalignment and decreased lubrication, while also maintaining the capacity to identify mature faults, such as chipped and missing gear teeth. The measurements are analyzed using statistical based methods – the Mahalanobis distance and Parzen discriminant analysis. These features for fault detection are then characterized at various operating speeds for each of the geartrain conditions of interest. An analytical model is created from first principles for verification of results and for simulation of the free and forced dynamics of the system.

Performance of Free Rolling and Powered Tillage Discs

This research study was done in the soil dynamics laboratory of Faculty of Agricultural Engineering, Kasetsart University, Kamphaengsaen Campus, Thailand, to understand the benefits of driven tillage disc by an external power compared to the conventional free rolling tillage disc under controlled experimental conditions. Performance of free rolling and power operated standard concave tillage disc was evaluated in the soil bin with a sandy loam soil (USDA classification). The setup consisted of soil bin system and measurement system. Double extended octagonal ring (DEOR) transducer and torque transducer with slip ring were used for forces and torque measurements. Different disc angles and disc speeds were considered for the study. Soil failure patterns of both discs were also studied. Driving disc by an external power found to be significantly affecting performance of tillage disc. Draft force of the disc observed at disc angles of 23 o, 28 o and 33 o was reduced from 620 N, 860 N and 947 N to 188 N, 254 N and 360 N respectively when free rolling disc was replaced by powered disc. However it increased torque acting on disc driving shaft. Similar trend can be observed in other kinds of soils, however trend will be positioned up or down on Y-axis depending on respective soil strength properties. Moreover, powered disc provided continuous and smooth flow of furrow slice to the side. Consequently, powered disc was proved advantageous over free rolling disc in terms of smooth soil displacement, easy soil volume handling, better inversion of the furrow slice and reduced soil reactions. Moreover it provided better energy utilization.

Residual strain effects on a non-contact magnetoelastic torque transducer

A non-contact magnetoelastic torque transducer consisting of a non-magnetic shaft with a portion of its length coated with a magnetostrictive material is studied. A phenomenological theory is developed for predicting the magnetic field of the transducer as a function of coating properties, residual strain, and applied torque. This theory takes into account stress-induced anisotropy and variations in magnetoelastic energy within the coating. The resulting model is used to investigate the effect of quiescent stress states on the sensitivity, hysteresis and linearity.

Development and Evaluation of Tractors and Tillage Implements Instrumentation System

Problem statement: Field machines contribute a major portion of the total cost of crop production. Proper selection and matching of farm machinery is essential in order to reduce the cost of crop production. Performance data for tractors and implements are, therefore, essential for farm machinery operators and manufacturers alike. The aim of this study was to develop and evaluate an instrumentation system for tractor and agricultural implements. Approach: An instrumentation system was developed and mounted on an MF 3090 tractor to measure and record data for the various performance parameters of the tractor and attached tillage implements. The system was designed to measure: drawbar pull, three-point linkage forces, rear and front wheel forces, PTO torque, ground speed, tillage depth, fuel consumption, engine speed and fluid temperatures. Results: The system performed well during the field operations and the results obtained showed that the accuracies of the transducers were acceptable. The wheel torque and weight transducers measured the torque and forces acting on the tractor wheels with high accuracy. The other transducers measured the vertical and the horizontal forces on mounted implements of categories II (40-100 hp) and III (80-225 hp). The field tests showed significant increase in the draft with increases in the depth and speed. A general regression equation to predict draft of the implements was developed. Conclusion: The system was capable of measuring the draft of primary tillage implements on sandy loam soils at various speeds and depths with high accuracy. The data was recorded, displayed and analyzes simultaneously.

A quantitative assessment of torque-transducer models for magnetoreception

Although ferrimagnetic material appears suitable as a basis of magnetic field perception in animals, it is not known by which mechanism magnetic particles may transduce the magnetic field into a nerve signal. Provided that magnetic particles have remanence or anisotropic magnetic susceptibility, an external magnetic field will exert a torque and may physically twist them. Several models of such biological magnetic-torque transducers on the basis of magnetite have been proposed in the literature. We analyse from first principles the conditions under which they are viable. Models based on biogenic single-domain magnetite prove both effective and efficient, irrespective of whether the magnetic structure is coupled to mechanosensitive ion channels or to an indirect transduction pathway that exploits the strayfield produced by the magnetic structure at different field orientations. On the other hand, torque-detector models that are based on magnetic multi-domain particles in the vestibular organs turn out to be ineffective. Also, we provide a generic classification scheme of torque transducers in terms of axial or polar output, within which we discuss the results from behavioural experiments conducted under altered field conditions or with pulsed fields. We find that the common assertion that a magnetoreceptor based on single-domain magnetite could not form the basis for an inclination compass does not always hold.

The influence of brake pads thermal conductivity on passenger car brake system efficiency

In phase of vehicle braking system designing, besides of mechanical characteristics, it is also necessary to take under consideration the system?s thermal features. This is because it is not enough just to achieve proper braking power, for the brake system to be effective but equally important thing is the dissipation of heat to the environment. Heat developed in the friction surfaces dissipate into the environment over the disk in one hand and through the brake linings and caliper, in the other. The striving is to make that greatest amount of heat to dissipate not threw the brake pads but threw disc. The experimental researching of heat transfer process taking place at vehicle brakes was made in the R&amp;D Center of ?Zastava automobili? car factory in order to increase the efficiency of brake system. The standard laboratory and road test procedures were used, according to factory quality regulations. The modern equipment such as thermo camera, thermo couples, torque transducers, signal amplifiers, optical speed measuring system and laptop computer were used. In this paper will be shown the part of the experimental researching, which refers to the thermal conductivity of brake pad friction linings.

Final report on the torque key comparison CCM.T-K1.1: Measurand torque: 0 N m, 500 N m, 1000 N m

The purpose of the CIPM subsequent bilateral comparison CCM.T-K1.1 was to link another participant, namely the National Physical Laboratory of India (NPLI), to the CCM.T-K1 torque key comparison.The measuring capabilities up to 1000 N m of dead-weight torque standard machines with supported lever were investigated. The pilot laboratory was the same in both comparisons – it was the Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany). The same two very stable torque transducers with well-known properties were used as travelling standards. The measurements at the participating laboratory were carried out in May 2007. According to the technical protocol, torque steps of 500 N m and 1000 N m had to be measured both in clockwise and anticlockwise directions. Corrections had to be applied to the results reported by the participants, taking into account the use of different amplifiers, the creep (due to different loading times of the machines) and the environmental conditions in the laboratories (temperature and relative humidity of the ambient air).The results of the pilot laboratory in this bilateral comparison are in very good agreement with the same results obtained in the CCM.T-K1 comparison. For each of the transducers, the two torque steps and both senses of direction of the torque vector, the key comparison reference value of the CCM.T-K1 was taken, and the degrees of equivalence of NPLI were calculated with respect to these values. The agreement between the results is very good. The smallest expanded relative uncertainty of the machine stated by the participant is 1 × 10−4. The results of the comparison support this uncertainty statement.Main text.To reach the main text of this paper, click on Final Report.Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Final report on the torque comparison EURAMET.M.T-S1: Measurand torque: 1 N m, 5 N m, 10 N m, 50 N m, 200 N m, 500 N m and 1000 N m

The purpose of the EURAMET supplementary bilateral comparison EURAMET.M.T-S1 was to compare the capabilities of reference-type static torque measuring machines. The pilot laboratory was the Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany); the other participant was the Egyptian national metrology institute NIS.Four very stable torque transducers with well-known properties and measuring ranges of 5 N m, 10 N m, 200 N m and 1000 N m were used as travelling standards. The measurements at the participating laboratories were carried out between May and August 2008. According to the technical protocol, two torque steps, corresponding to 100% (all transducers) and 50% (10 N m, 1000 N m), 40% (200 N m) or 20% (5 N m) of the transducer's capacity, had to be measured both in clockwise and anticlockwise directions. Corrections were applied to the results reported by the participants taking into account the use of different amplifiers and the environmental conditions in the laboratories (temperature and relative humidity of the ambient air).For each of the transducers, the two torque steps and both senses of direction of the torque vector, a comparison reference value was calculated.The agreement between the results is very good. The smallest expanded relative uncertainty of the machines stated by the participants is 2 × 10−4 for machines with horizontal axis. The results of the comparison support this uncertainty statement. The 5 N m transducer showed deviating results in the 100% step for clockwise torque, whereas the results for anticlockwise torque are also in good agreement. The reason for this deviation is probably caused by an unstable transducer or an erroneous measurement.Main text.To reach the main text of this paper, click on Final Report.Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

“Negative” Hysteresis in Magnetoelastic Torque Transducers

Unusual manifestations of magnetomechanical hysteresis often observed in magnetoelastic torque transducers are described. Characterized by a remanent field at zero torque having a polarity opposite to that at the torque peak, this hysteretic effect is shown to be of magnetic origin and hypothesized to reflect axial magnetization of unpolarized material radially inward of the circumferentially polarized band. The retained portion of this magnetization at zero torque is shown both by analysis and experimental results with an electromagnetic simulator to be a source of magnetic field having opposite polarity to that present at the previous torque peak. When this field becomes larger than the normal positive remanent field it appears as negative hysteresis.

Torque traceability examination of calibration laboratories in Korea

Torque is a physical quantity that is related to fastening bolt in various industry fields of assembling. The quality of assembling procedure is highly dependent on the accurate torque control. For the accurate torque measurement and control of torque, each torque transducer in industries should be calibrated using qualified torque calibration system. In Korea, there are 14 calibration laboratories for the torque measuring device. They have their own torque calibration system. Some of them are using deadweight torque calibration machine and the others have unsupported torque generating system using torque arm and masses. To check the reliability of the torque calibration laboratories, a series of round robin measurement was performed by the Korean National Measurement Institute, Korea Research Institute of Standards and Science (KRISS). This paper deals with the round robin measurement to check the traceability in torque in Korea. Two torque transfer standards each having 200 Nm capacity were used for the measurement. Measured value as well as the measured uncertainty of each laboratory was compared with those of KRISS.

Traceability of torque transducers under rotating and dynamic operating conditions

Torque transducers in industrial applications are usually used under dynamic and rotating operating conditions. The present article provides a survey of state-of-the-art studies which describe methods for providing traceability of torque measurements under such operating conditions. The method of investigating the effects of rotation is a comparison of measurements of torque in a rotating shaft train gained simultaneously with two different methods. The first method is using a rotating torque transducer, the second one is with a cradle-mounted absorption dynamometer. The method for investigating the effects of dynamic torque is based on experiments with periodic torque but only minimal rotational motion. Torque is generated by a rotary exciter which forces a setup with a torque transducer and some auxiliary components into a periodic rotary motion. The torque measurement provided by the torque transducer is compared to a reference torque. The reference torque is gained by accurately measuring the angular acceleration of the rotation in conjunction with a priori knowledge of the mass moment of inertia. The developments on the periodic dynamic torque have been performed by the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. The investigations on rotating torque transducers have been performed by Hottinger Baldwin Messtechnik (HBM), Germany, a manufacturer of torque transducers with a wide experience in torque calibration.

Combustion stability analysis during engine stop and restart in a hybrid powertrain

A cycle-resolved analysis system was designed with the specified measurement instruments to investigate the characteristics of combustion stability in a mild gasoline hybrid powertrain. A Fast Response Flame Ionization Detector (FFID), cylinder pressure transducer and engine torque transducer were used to observe both the engine-out THC emissions and engine performance during a brief moment of engine restart. This research aimed to improve combustion stability and was performed by varying the battery State Of Charge (SOC), injection duration and ignition timing. The results indicate that engine combustion tends to be more stable with longer fuel injection durations and advanced ignition timing, while the effect of the battery SOC is negligible. Also, peculiar differences in the catalyst conversion efficiency at the front and rear of the catalyst during engine restart and deceleration were revealed, with the degree of HC oxidation being the suspected cause. This study not only analyzed the engine control and engine-out total hydrocarbon (THC) emission characteristics, but also implemented control strategies that allowed for combustion stability during engine stop and restart operation.

Mental techniques during manual stretching in spasticity — a pilot randomized controlled trial

Objective: To evaluate the feasibility and effects of using motor imagery during therapeutic stretching in individuals with spasticity. Design: Randomized single-blind controlled pilot trial. Setting: Chronic day care unit, neurological rehabilitation unit and in the community. Subjects: Eleven individuals with spasticity in the arm requiring stretching as part of their normal routine. Interventions: In addition to their normal stretching routine, subjects in the experimental group received motor imagery during their stretches (n = 6). The control group received progressive muscle relaxation during their stretches (n = 5). The dose varied between 8 and 56 sessions over eight weeks. Main measures: Resistance to passive movement, measured with a torque transducer, passive range of movement, measured with an electro-goniometer, Modified Ashworth Scale (MAS) and level of discomfort during the MAS were assessed at baseline and after eight weeks by an independent assessor. These measures were recorded before and after a stretch intervention on both assessments. Results: Participants, therapists and carers tolerated the techniques well. Compliance was variable and adherence was good. Mixed ANOVA showed no difference over time and no difference between the motor imagery and progressive muscle relaxation group on the primary and secondary outcome measures (P>0.05). Conclusions: It is feasible to use motor imagery during therapeutic stretching. Statistical power was low due to the large variability in the population and the small sample size. Post-hoc sample size calculation suggests that future studies of this subject should include at least 54 participants per group. Further research is warranted.

A Biophysical Mechanosensor Model for T-Cell Receptor Signaling

T-cells (cytolytic, helper and others) are vital components in adaptive mammalian immune defense systems. T-cell receptor (TCR) signaling which follows recognition of a peptide antigen bound to an MHC molecule (pMHC) on an antigen presenting cell (APC) is critical for T-cell activation, differentiation, and proliferation. For decades, the mechanism for TCR signaling across the T-cell membrane by this multi-subunit receptor has remained a mystery. Based on our recently obtained structural data on stimulatory and non-stimulatory anti-TCR antibodies and their binding footprint to TCR components obtained by NMR, we present here a simple but all-inclusive “dynamic torque transducer” model for TCR signaling. Extracellular mechanical torque can result in quaternary structure changes between the pMHC-binding TCR alpha/beta chains and the non-convalently linked CD3 chains within the TCR complex, triggering downstream signaling via ITAMs in the CD3 cytoplasmic tails. In this process, the pMHC behaves as a detachable effort arm of this complex-lever system; its binding is determined by the specificity of an individual TCR but is not sufficient to mediate signal transduction per se. An external torque is additionally required to provide the energy for this signaling. Such a torque can be generated either via a shear force or vertical pressure between the opposing APC and T cell membranes. The former “bind-and-tug” mode may be responsible for initial signaling during T-cell scanning of APCs, while the latter “bind-and-bend” mode is responsible for sustained signaling inside immune-synapses during T-cell activation. Our model can also explain T-cell signaling mediated by antibody or multimeric pMHC cross-linking. This mechanism of converting mechanical energy to a biochemical signal, mediated and controlled by a detachable interface, may be generally applicable in other cell-cell signaling systems both within and outside of the immune system.

Final report on the torque key comparison CCM.T-K1.Measurand torque: 0 N m, 500 N m, 1000 N m

The purpose of the CIPM comparison CCM.T-K1 was to compare the measuring capabilities up to 1000 N m of deadweight torque standard machines with supported lever in national metrology institutes. Eight institutes participated, with the Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany) acting as pilot laboratory. Two very stable torque transducers with well-known properties were used as travelling standards. The circulation of these transducers started June 2005 and ended in July 2006. According to the technical protocol, torque steps of 500 N m and 1000 N m had to be measured both in clockwise and anticlockwise directions. Corrections had to be applied to the results reported by the participants taking into account the use of different amplifiers, the creep (due to different loading times of the machines) and the environmental conditions in the laboratories (temperature and relative humidity of the ambient air). For each of the transducers, the two torque steps and both senses of direction of the torque vector, a key comparison reference value was calculated.With one exception at anticlockwise torque, the agreement between the results is very good. The smallest expanded relative uncertainty of the machines stated by the participants is 2 × 10-5 both for machines with horizontal or vertical axis. The results of the comparison support these uncertainty statements. One participant had problems with anticlockwise torque. These results were not used for the calculation of the corresponding reference values.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Jar-opening challenges. Part 1: An apparatus for assessing hand and finger torques and forces in a jar-opening activity

A simulated jar apparatus was developed to record hand kinetics and torque contribution of a digit during jar-opening activities. The design of the apparatus, namely a jar body and a lid, is similar to a commercial jam jar that is regularly seen in daily living. One six-axis force-torque transducer and a torque cell were mounted inside the jar lid to detect the external force exerted from the digit and fixed on to the jar body to record the overall torque generated by the hand and wrist respectively. The applications of the apparatus were used to test the twisting torque of the hand and to measure the applied forces of the digit, which are both important factors in opening a jar. The contribution of each digit relative to the total twisting torque of the hand could be obtained via the apparatus. The intraclass correlation coefficient of the repeated measurements of the obtained forces and moments for different counterweights was approximately 0.96-1.00, which indicates that the reliability of the measured components of the apparatus is high. The high coefficient of determination (r2 > 0.99) indicates high accuracy of prediction of the measured values with respect to the expected loads. The validation outcomes support the design rationale and actual body part of the simulated jar. In addition, understanding the contribution of a single digit in opening a jar was also achieved via the apparatus and model.

Analysis of a non-contact magnetoelastic torque transducer

Results are presented for the performance of a magnetoelastic torque transducer that converts a torque-induced strain in a non-magnetic shaft into changes in a measurable magnetic field. The magnetic field is generated by a thin magnetostrictive layer that is coated onto the circumference of the shaft. The layer is magnetized and has an initial residual strain. The magnetization within the layer rotates in response to changes in the strain which occur when the shaft is torqued. The magnetic field produced by the layer changes with the magnetization and this can be sensed by a magnetometer to monitor the torque on the shaft. In this paper, a phenomenological theory is developed for predicting the performance of the transducer. The theory can be used to predict the magnetic field distribution of the transducer as a function of the physical properties of the magnetic coating, its residual strain, and the applied torque. It enables rapid parametric analysis of transducer performance, which is useful for the development and optimization of novel non-contact torque sensors.