Journal articles on the topic 'Force-Position Transducer'
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Cormie, Prue, Jeffrey M. McBride, and Grant O. McCaulley. "Validation of Power Measurement Techniques in Dynamic Lower Body Resistance Exercises." Journal of Applied Biomechanics 23, no. 2 (May 2007): 103–18. http://dx.doi.org/10.1123/jab.23.2.103.
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The objective of this study was to investigate the validity of power measurement techniques utilizing various kinematic and kinetic devices during the jump squat (JS), squat (S) and power clean (PC). Ten Division I male athletes were assessed for power output across various intensities: 0, 12, 27, 42, 56, 71, and 85% of one repetition maximum strength (1RM) in the JS and S and 30, 40, 50, 60, 70, 80, and 90% of 1RM in the PC. During the execution of each lift, six different data collection systems were utilized; (1) one linear position transducer (1-LPT); (2) one linear position transducer with the system mass representing the force (1-LPT+MASS); (3) two linear position transducers (2-LPT); (4) the force plate (FP); (5) one linear position transducer and a force plate (1-LPT+FP); (6) two linear position transducers and a force place (2-LPT+FP). Kinetic and kinematic variables calculated using the six methodologies were compared. Vertical power, force, and velocity differed significantly between 2-LPT+FP and 1-LPT, 1-LPT+MASS, 2-LPT, and FP methodologies across various intensities throughout the JS, S, and PC. These differences affected the load–power relationship and resulted in the transfer of the optimal load to a number of different intensities. This examination clearly indicates that data collection and analysis procedures influence the power output calculated as well as the load–power relationship of dynamic lower body movements.
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Huang, Yi Cheng, and Kun Yang Li. "Numerical Simulation and Experimental Study on Bonding Tool Design of Thermosonic Transducer for Flip-Chip Bonding." Applied Mechanics and Materials 157-158 (February 2012): 1670–73. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.1670.
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In this paper, the study for the bonding tool position of ultrasonic transducers for thermosonic Flip-Chip LED bonding is presented. Improving the efficiency of ultrasonic transducers plays an important role in the bonding process. To obtain the actual movement of ultrasonic transducer, finite element method ATILA was employed to get more detailed information. To verify the reliability of simulation results, the impedance characteristic and resonance frequency of the transducer mechanical system have been measured using a LCR meter. Moreover, different mounting position of bonding tool on the transducer was studied. Use ATILA to find the best tool position, and vibration amplitude of the tool was measured by Laser Doppeler Vibrometer. Experimental bonding results are verified by in-house shear force test bed.
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Evreinov, Grigori, and Roope Raisamo. "One-directional position-sensitive force transducer based on EMFi." Sensors and Actuators A: Physical 123-124 (September 2005): 204–9. http://dx.doi.org/10.1016/j.sna.2005.02.011.
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Martin, K. F., and H. Lockman. "Force Sensing in Magnitude, Direction, and Position." Journal of Dynamic Systems, Measurement, and Control 109, no. 3 (September 1, 1987): 286–90. http://dx.doi.org/10.1115/1.3143856.
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A sensing device is described which measures the magnitude, direction, and position of force in the plane of the sensor. The basic sensing method is by strain gauge bridges, the outputs of which are amplified and fed via Analogue to Digital (A/D) converters to a microcomputer for calculation of the force characteristics. The transducer system is shown to be capable of measuring quasi static forces; experimental measurements confirming the feasibility of the device. Further research work is planned to improve the accuracy of the system and to ascertain and improve its capability of measuring dynamic forces.
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Pontiff, Mattie E., Li Li, and Noelle G. Moreau. "Reliability and Validity of Three Clinical Methods to Measure Lower Extremity Muscle Power." International Journal of Kinesiology and Sports Science 9, no. 1 (January 31, 2020): 1. http://dx.doi.org/10.7575/aiac.ijkss.v.9n.1p.1.
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Background: Lower extremity muscle power is critical for daily activities and athletic performance in clinical populations. Objective: The purpose of this study was to determine the reliability and validity of 3 clinically feasible methods to measure lower extremity muscle power during a leg press. Methods: Ten of 26 subjects performed 2 sessions of 5 submaximal leg presses separated by 3-7 days in this repeated-measures cross-sectional design; the remaining performed 1 test session. Power was calculated independently for each method [simple video, linear position transducer, and accelerometer] and compared to the reference force plate. Test-retest reliability was evaluated using intraclass correlation coefficients (ICC). Pearson’s correlation coefficient (r), Bland-Altman plots with 95% limits of agreement (LOA), and mean bias percentages (%) were used to determine relative and absolute validity. Results: Power measures were reliable for all methods (ICC=.97-.99). All were highly correlated with the force plate (r=.96-.98). Mean bias was -0.8% (LOA: -16.57% to 14.98%) (video), -13.21% (LOA: -23.81% to -2.61%) (position transducer) compared to the force plate. Proportional bias was observed for accelerometry. Conclusion: All methods were reliable and highly correlated with the force plate. Only the video and position transducer demonstrated absolute validity. The position transducer was the most feasible method because of its simplicity and accuracy in measuring power.
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Hartansky, Rene, Martin Mierka, Vladimir Jancarik, Mikulas Bittera, Jan Halgos, Michal Dzuris, Jakub Krchnak, Jaroslav Hricko, and Robert Andok. "Towards a MEMS Force Sensor via the Electromagnetic Principle." Sensors 23, no. 3 (January 21, 2023): 1241. http://dx.doi.org/10.3390/s23031241.
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Force measurement is a science discipline that experiences significant progress with the introduction of new materials and evaluation methods. Many different sensor types, working on different principles, have been developed and reviewed and have found use in medicine as well as many other industries. New trends and demands require a size reduction and simple applicability, with the use of, for example, micro electromechanical systems (MEMS). For purposes of this study, the initial MEMS body is supplemented by its scaled version. Force measurement in this study works on the force to time-delay conversion principle. A compact compliant mechanical body (CCMB) with an embedded parallel resonant circuit (PRC) acting as a transducer realizes the conversion. Depending on the resonant frequency of the transducer (CCMB or MEMS), we have measured the applied force based on the reverse influence of the transducer on the surrounding EM field. The analysis shows that the transducer’s resonant frequency has a detectable reverse influence on the voltage-controlled oscillator (VCO) DC supply current. The force influencing the transducer is determined by the DC supply current ripple position during the VCO frequency sweep. The study presents the method proposal and mathematical analysis, as well as its function verification by simulation and prototype measurements. The proposed principle was validated on a CCMB prototype capable of measuring forces up to ∼2.5 N at a sampling frequency of ∼23 kHz, while the measured time-delay ranges from 14.5 µs to 27.4 µs.
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Lee, Chang Hoon, Beom Hoon Park, Young Hun Kim, Hyeong Geun Jo, and Kwan Kyu Park. "Particle Manipulation in 2D Space Using a Capacitive Micromachined Ultrasonic Transducer." Micromachines 13, no. 4 (March 29, 2022): 534. http://dx.doi.org/10.3390/mi13040534.
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Ultrasonic particle manipulation is a noncontact method for controlling microscale objects, such as cells or microparticles, using an acoustic field. In this study, a 2D array of capacitive micromachined ultrasonic transducers (CMUTs), placed horizontally in immersion, generated ultrasonic waves in the vertical direction, and the oil’s surface increased due to the radiation force of the ultrasonic waves. In addition, the radiation force directly exerted a force on a floating particle. By measuring the movement of the reflected laser light by the moving oil surface, the height of the oil’s surface deformed by the acoustic radiation force (ARF) was measured. The ARF made a floating particle, as well as the oil’s surface, move. The particle moved radially away from the surface position above the transducer, and its velocity was determined by its position on the fluid’s surface. When a single channel was operated, it moved 0.4 mm at an average speed of 90 μm/s, and when two adjacent channels were operated, it moved 1.2 mm at a speed of 272 μm/s. The particles moved in any direction on the surface of the oil by controlling the actuation channel using an electrical switch.
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Harman, E., H. G. Knuttgen, and P. Frykman. "Automated data collection and processing for a cycle ergometer." Journal of Applied Physiology 62, no. 2 (February 1, 1987): 831–36. http://dx.doi.org/10.1152/jappl.1987.62.2.831.
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A system is described for collection and processing of data from a cycle ergometer. Cycle pedals, specially made to withstand the extremely high forces exerted during maximal power cycling, contain transducers to measure pedal angle relative to the crank and foot forces both perpendicular and parallel to the pedal surface. An additional transducer monitors crank position. Output signals are conditioned, amplified, digitized by a 12-bit analog-to-digital converter, fed into a computer at 100 Hz/channel, and mathematically smoothed to attenuate noise. For each sample interval, foot force components perpendicular and parallel to the crank arm are calculated. Power generated on each crank revolution is determined from transducer information. Computer graphics display pedaling parameters vs. crank angle in both rectangular and circular format. Data files containing variables descriptive of pedaling force curves are produced to enable computerized statistical analysis of cycling performance.
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Bansevicius, Ramutis, Dalius Mazeika, Vytautas Jurenas, Genadijus Kulvietis, and Asta Drukteiniene. "Multi-DOF Ultrasonic Actuators for Laser Beam Positioning." Shock and Vibration 2019 (February 10, 2019): 1–13. http://dx.doi.org/10.1155/2019/4919505.
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A novel design concept of multi-degree-of-freedom (multi-DOF) piezoelectric actuator is introduced in the paper. The main idea is to connect two identical piezoelectric transducers by hyperelastic material in order to increase the total number of degrees-of-freedom of the system. Such design principle also allows to separate vibrations of two piezoelectric transducers and to control them independently. The ring- and cylinder-type piezoelectric transducers were used to design two multi-DOF ultrasonic actuators for precise laser beam positioning. Reflecting mirror is mounted on the top of the actuator and is preloaded by magnetic force. Both disc- and cylinder-type actuators can realize up to six degrees-of-freedom, i.e., to rotate the mirror about three axes employing one transducer and to position mirror in the plane by using another transducer. Bidirectional rotation and translation motion of the mirror are obtained by switching excitation signals between different electrodes of the transducers. Both the numerical simulation and physical prototype were used to verify operating principle of the actuators. Numerical investigation of the piezoelectric actuator was performed to investigate modal-frequency and harmonic response analysis while experimental study was performed to measure electrical and mechanical output characteristics of the piezoelectric actuator. A mathematical model of contacting force control was proposed, and numerical verification was performed when the mirror need to be rotated according to the specific motion trajectory.
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Pittman, Lora J., and E. Fiona Bailey. "Genioglossus and Intrinsic Electromyographic Activities in Impeded and Unimpeded Protrusion Tasks." Journal of Neurophysiology 101, no. 1 (January 2009): 276–82. http://dx.doi.org/10.1152/jn.91065.2008.
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Eight muscles invest the human tongue: four extrinsic muscles have external origins and insert into the tongue body and four intrinsic muscles originate and terminate within the tongue. Previously, we noted minimal activation of the genioglossus tongue muscle during impeded protrusion tasks (i.e., having subjects push the tongue against a force transducer), suggesting that other muscles play a role in the production of tongue force. Accordingly, we sought to characterize genioglossus tongue muscle activities during impeded and unimpeded protrusion tasks (i.e., having subjects slowly and smoothly move the tongue out of their mouth). Electromyographic (EMG) and single motor-unit potentials of the extrinsic genioglossus muscle were recorded with tungsten microelectrodes and EMG activities of intrinsic tongue muscles were recorded with hook-wire electrodes inserted into the anterior tongue body. Tongue position was detected by an isotonic transducer coupled to the tongue tip. Protrusive force was detected by a force transducer attached to a rigid bar. Genioglossus and intrinsic tongue muscles were simultaneously active in both impeded and unimpeded protrusion tasks. Genioglossus whole muscle EMG and single motor-unit activities changed faithfully as a function of tongue position, with increased discharge associated with protrusion and decreased discharge associated with retraction back to the rest position. In contrast, during the impeded protrusion task drive the genioglossus muscle remained constant as protrusion force increased. Conversely, intrinsic tongue muscle activities appropriately followed changes in both tongue position and force. Importantly, we observed significantly higher levels of intrinsic muscle activity in the impeded protrusion task. These observations suggest that protrusion of the human tongue requires activation of the genioglossus and intrinsic protrudor muscles, with the former more important for establishing anterior–posterior tongue location and the latter playing a greater role in the generation of protrusive force. A biomechanical model of these actions is provided and discussed.
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Quinn, T. P., and C. D. Mote. "A Six-Degree-of-Freedom Acoustic Transducer for Rotation and Translation Measurements Across the Knee." Journal of Biomechanical Engineering 112, no. 4 (November 1, 1990): 371–78. http://dx.doi.org/10.1115/1.2891199.
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An acoustic transducer design to measure the relative translations and rotations across the knee with no mechanical coupling between the tibia and femur is presented. Platforms attached to femoral and tibial tracking fixtures hold acoustic sources and receivers, respectively. The distance from each source to each receiver is measured by the acoustic transit time and the translations and rotations across the knee joint are computed. For rotations less than 30 deg around the expected operating position, the resolution of the transducer is 0.3 deg; for translations less than 1.5 cm around the expected operating position, the resolution is 0.03 cm. Theoretical error analysis using a Monte Carlo method shows that the uncertainty in the measurement depends on the relative position of the sources and receivers. The analysis predicts the worst case resolution of the transducer as 0.09 cm in translation and 0.6 deg in rotation when the receiver platform is translated 8.0 cm parallel to the source platform. The transducer and fixturing system are demonstrated on a cadaver specimen for applied anterior force and applied internal-external rotation. Errors due to (soft tissue) motion of the transducer relative to the bone during in vivo measurements are assessed on the cadaver specimen. For internal-external rotation the error due to soft tissue motion is a maximum of 0.5 cm in translation and 1.8 deg in rotation. For applied anterior force the error due to soft tissue motion is a maximum of 0.16 cm in translation and 2.7 deg in rotation.
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Bertram, J. E. A., K. Gellman, J. W. Hermanson, and K. K. Haussler. "Dynamic Analysis of In Vivo Segmental Spinal Motion: An Instrumentation Strategy." Veterinary and Comparative Orthopaedics and Traumatology 13, no. 01 (2000): 9–17. http://dx.doi.org/10.1055/s-0038-1632623.
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SummarySummary A transducer for measuring threedimensional segmental spinal motion was designed to directly measure dynamic rotations (Rx, Ry and Rz) about three orthogonal axes using an array of liquid metal strain gauges (LMSGs). The configuration of the LMSG array results in differential length changes due to segmental spinal motion. In vitro calibration utilized transducer attachment to Steinmann pins implanted into the dorsal spinous processes of anatomical spinal segments. The response of the LMSGs approximated linearity (R2 ≥0.980) over the calibrated ranges of angular displacement (i.e., ± 5°). On average, artifactual mechanical noise of the LMSGs was <3% of the signal recorded during locomotion. The minimum resolution of the transducer was 0.07 degrees of flexion-extension, 0.46 degrees of lateral bending, and 0.56 degrees of rotation. Average resistive force for all transducers was 0.31 ± 0.05 Nm at the neutral articular position (0°) and 0.51 ± 0.03 Nm at 5° of flexion. Clinically, the modest mechanical resistance of the transducers did not affect spinal mobility nor locomotion. In vivo application of the transducer was demonstrated at thoracolumbar and lumbosacral spinal segments in horses treadmill locomotion. The transducer was designed and tested on an equine model, but may be adapted for other quadrupeds. The dynamic and continuous measure of three-dimensional in vivo segmental spinal motion will provide an important new perspective for evaluating normal and altered spinal motion.A technique was developed for directly measuring threedimensional segmental spinal motion in the thoracolumbar and lumbosacral spinal segments in horses during treadmill locomotion. The dynamic and continuous measure of three-dimensional in vivo segmental spinal motion will provide an important new perspective for evaluating normal and altered spinal motion associated with back problems.
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Goertz, R., C. Egger, M. Neurath, and D. Strobel. "Impact of Food Intake, Ultrasound Transducer, Breathing Maneuvers and Body Position on Acoustic Radiation Force Impulse (ARFI) Elastometry of the Liver." Ultraschall in der Medizin - European Journal of Ultrasound 33, no. 04 (June 21, 2012): 380–85. http://dx.doi.org/10.1055/s-0032-1312816.
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Abstract Purpose: Since acoustic radiation force impulse (ARFI) elastometry is an increasingly popular method for the assessment of hepatic fibrosis and cirrhosis, we investigated factors possibly influencing hepatic elastometric measurements. Materials and Methods: 30 healthy volunteers (17 females, 13 males) were recruited. The shear wave velocity of the right liver lobe was determined in a fasting upright and supine position and after different breathing maneuvers with the convex array (4C1) and in a supine position with the linear (9L4) ultrasound transducer. In 18 volunteers, subsequent measurements were obtained in a fasting state and 30, 60, 90 and 120 min after ingestion of a standardized breakfast. A group of 8 patients (average age: 76 years) with right heart insufficiency was also evaluated. Results: In the fasting state, the ARFI shear wave velocities measured in an upright position were significantly higher than those in supine position (p< 0.0001). The supine ARFI values were significantly higher with the linear transducer than with the convex transducer (p = 0.0034). The results in deep inspiration, deep expiration and during Valsalva maneuver showed no differences. The food intake-related ARFI elastometric measurements were significantly elevated at time points 30 min (p = 0.019) and 60 min (p = 0.036) postprandial. In right heart insufficiency, the ARFI values were elevated. Conclusion: Hepatic ARFI elastometry is a well evaluated method. A standardized examination should include measuring in a supine position with the convex transducer (4C1) without specific breathing maneuvers. Since ARFI elastometry values increase after food intake, measurements should be performed in the fasting state, or not earlier than 2 hours postprandially. Heart dysfunction may impair ARFI accuracy.
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Lee, Gil U., Linda Chrisey, and Richard J. Colton. "Measuring forces between biological macromolecules with the Atomic Force Microscope: characterization and applications." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 718–19. http://dx.doi.org/10.1017/s0424820100139962.
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Structure and function in biological macromolecular systems such as proteins and polynucleotides are based on intermolecular interactions that are short ranged and chemically specific. Our knowledge of these molecular interactions results from indirect physical and thermodynamic measurements such as x-ray crystallography, light scattering and nuclear magnetic resonance spectroscopy. Direct measurement of molecular interaction forces requires that the state of a system be monitored with near atomic resolution while an independent force is applied to the system of 10−12 to 10−9 Newton magnitude. The atomic force microscope (AFM) has recently been applied to the study of single molecular interactions. The microfabricated cantilever of the AFM, a force transducer of small yet variable stiffness and high resonance frequency, produces a transducer of 10−15 N/Hz1/2 force sensitivities and 0.01 nm position accuracy.This presentation describes the AFM measurement of the molecular interaction forces in the model ligand-receptor system streptavidin-biotin and between complementary strands of DNA.
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Moghimi, Hanieh, Shahriar Shahab, Zeinab Azizi, Alireza Akbarzade Baghban, Mahdi Niknami, Noureddin Nakhostin Ansari, Ali Kavoosi, and Mohammad Ali Moghimi. "Relationship between the Mandibular Condyle Position and the Bite Force in the People with Normal Temporomandibular Joint." International Journal of Dentistry 2023 (February 16, 2023): 1–6. http://dx.doi.org/10.1155/2023/2517983.
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Statement of the Problem. The mandibular condyle position is important in temporomandibular joint (TMJ) disorders. The bite force is a mechanical force that may affect the condylar position. Purpose. To investigate the relationship between condylar position in the glenoid fossa and maximum bite force in adults with normal temporomandibular joint. Materials and Methods. In this cross-sectional study, 23 subjects (21 females and 2 males; mean age 38.88 ± 11.7 years) with 41 joints participated. Right and left joints were examined using cone-beam computed tomography. Maximum bite force was measured using the strain gauge transducer in the regions of right molar, left molar, and incisors. Pearson correlation coefficient, paired sample t-test, and binary logistic regression were employed for analysis. Results. The mean maximum bite force was 169.09 ± 87.7 N. The most common position of the condyle was anterior (n = 36) and inferior (n = 31). The mean of mandibular condyle joint spaces for right and left sides were not statistically significant ( P > 0.05 ). There were no relationships between the condylar positions and the mean maximum bite force ( P > 0.05 ). Conclusion. The condylar positions in the glenoid fossa are not related to the bite force in the people with normal temporomandibular joint.
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McMillan, D. W., D. S. McNally, G. Garbutt, and M. A. Adams. "Stress Distributions inside Intervertebral Discs: The Validity of Experimental ‘Stress Profilometry’." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 210, no. 2 (June 1996): 81–87. http://dx.doi.org/10.1243/pime_proc_1996_210_396_02.
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This paper evaluates a technique for measuring the distribution of compressive stress within cadaveric intervertebral discs. A strain-gauged pressure transducer, side-mounted near the tip of a 1.3 mm diameter needle, was inserted into cubes of disc tissue and into intact discs. Regardless of the position and orientation of the transducer within the tissue or disc, its output was found to be proportional to the compressive force applied to the specimen. The distribution of compressive stress was measured by pulling the instrumented needle through the specimen and the resulting stress profiles were reproducible to within 20 per cent. Profiles obtained at different applied loads showed a similar distribution of stress within the disc, suggesting that the compressive stress at any location and direction increased in proportion to the applied load. Since transducer output was also proportional to applied load, it was reasoned that it must be proportional to compressive stress within the disc. The average vertical compressive stresses acting on various regions within a disc were calculated from the stress profiles and multiplied by the cross-sectional area of each region: the resulting force was then compared with the known applied force in order to assess the calibration coefficient of the transducer. Agreement between the two forces was good, indicating that the calibration coefficient established in a saline bath was applicable to disc tissues also. However, artifactual stress peaks could be generated if the transducer was pulled across a bony asperity. It is concluded that the transducer measures the mean compressive stress acting upon it within disc tissues. Errors associated with the technique are small compared to differences in stress distributions which occur naturally, for example when intervertebral discs are loaded to simulate different postures in a living person.
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Newell, Philip B., Eric L. Dugan, and Sarah E. Kruger. "Linear Position Transducer / Force Platform Method For Determining Power Output During Free-standing Jump Squats." Medicine & Science in Sports & Exercise 37, Supplement (May 2005): S410. http://dx.doi.org/10.1249/00005768-200505001-02113.
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Newell, Philip B., Eric L. Dugan, and Sarah E. Kruger. "Linear Position Transducer / Force Platform Method For Determining Power Output During Free-standing Jump Squats." Medicine & Science in Sports & Exercise 37, Supplement (May 2005): S410. http://dx.doi.org/10.1097/00005768-200505001-02113.
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Hunter, Sandra K., Tejin Yoon, Joseph Farinella, Erin E. Griffith, and Alexander V. Ng. "Time to task failure and muscle activation vary with load type for a submaximal fatiguing contraction with the lower leg." Journal of Applied Physiology 105, no. 2 (August 2008): 463–72. http://dx.doi.org/10.1152/japplphysiol.90398.2008.
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The purpose was to compare the time to failure and muscle activation patterns for a sustained isometric submaximal contraction with the dorsiflexor muscles when the foot was restrained to a force transducer (force task) compared with supporting an equivalent inertial load and unrestrained (position task). Fifteen men and women (mean ± SD; 21.1 ± 1.4 yr) performed the force and position tasks at 20% maximal voluntary contraction force until task failure. Maximal voluntary contraction force performed before the force and position tasks was similar (333 ± 71 vs. 334 ± 65 N), but the time to task failure was briefer for the position task (10.0 ± 6.2 vs. 21.3 ± 17.8 min, P < 0.05). The rate of increase in agonist root-mean-square electromyogram (EMG), EMG bursting activity, rating of perceived exertion, fluctuations in motor output, mean arterial pressure, and heart rate during the fatiguing contraction was greater for the position task. EMG activity of the vastus lateralis (lower leg stabilizer) and medial gastrocnemius (antagonist) increased more rapidly during the position task, but coactivation ratios (agonist vs. antagonist) were similar during the two tasks. Thus the difference in time to failure for the two tasks with the dorsiflexor muscles involved a greater level of neural activity and rate of motor unit recruitment during the position task, but did not involve a difference in coactivation. These findings have implications for rehabilitation and ergonomics in minimizing fatigue during prolonged activation of the dorsiflexor muscles.
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Hunter, Sandra K., Daphne L. Ryan, Justus D. Ortega, and Roger M. Enoka. "Task Differences With the Same Load Torque Alter the Endurance Time of Submaximal Fatiguing Contractions in Humans." Journal of Neurophysiology 88, no. 6 (December 1, 2002): 3087–96. http://dx.doi.org/10.1152/jn.00232.2002.
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Endurance time, muscle activation, and mean arterial pressure were measured during two types of submaximal fatiguing contractions that required each subject to exert the same net muscle torque in the two tasks. Sixteen men and women performed isometric contractions at 15% of the maximum voluntary contraction (MVC) force with the elbow flexor muscles, either by maintaining a constant force while pushing against a force transducer (force task) or by supporting an equivalent inertial load while maintaining a constant elbow angle (position task). The endurance time for the force task (1402 ± 728 s) was twice as long as that for the position task (702 ± 582 s, P < 0.05), despite a similar reduction in the load torque at exhaustion for each contraction. The rate of increase in average electromyographic activity (EMG, % peak MVC value) for the elbow flexor muscles was similar for the two tasks. However, the average EMG was greater at exhaustion for the force task (22.4 ± 1.2%) compared with the position task (14.9 ± 1.0%, P < 0.05). In contrast, the rates of increase in the mean arterial pressure, the rating of perceived exertion, anterior deltoid EMG, and fluctuations in motor output (force or acceleration) were greater for the position task compared with the force task ( P < 0.05). Furthermore, the rate of bursts in EMG activity, which corresponded to the transient recruitment of motor units, was greater for the brachialis muscle during the position task. These results indicate that the briefer endurance time for the position task was associated with greater levels of excitatory and inhibitory input to the motor neurons compared with the force task.
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Liang, W., X. X. Yang, and Y. H. Jao. "Effect of load pad shape on the position error of column type strain gauge force transducer." Journal of Physics: Conference Series 1065 (August 2018): 042034. http://dx.doi.org/10.1088/1742-6596/1065/4/042034.
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Ruben, R. M., H. Saffel, J. L. McCrory, P. Cormie, and G. G. Haff. "Comparison of Accelerometer Based Vertical Jump Assessments to a Linear Position Transducer Plus Force Plate System." Journal of Strength and Conditioning Research 25 (March 2011): S37. http://dx.doi.org/10.1097/01.jsc.0000395636.70853.92.
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Rudroff, Thorsten, Benjamin K. Barry, Amy L. Stone, Carolyn J. Barry, and Roger M. Enoka. "Accessory muscle activity contributes to the variation in time to task failure for different arm postures and loads." Journal of Applied Physiology 102, no. 3 (March 2007): 1000–1006. http://dx.doi.org/10.1152/japplphysiol.00564.2006.
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Time to failure and electromyogram activity were measured during two types of sustained submaximal contractions with the elbow flexors that required each subject to exert the same net muscle torque with the forearm in two different postures. Twenty men performed the tasks, either by maintaining a constant force while pushing against a force transducer (force task), or by supporting an equivalent load while maintaining a constant elbow angle (position task). The time to failure for the position task with the elbow flexed at 1.57 rad and the forearm horizontal was less than that for the force task (5.2 ± 2.6 and 8.8 ± 3.6 min, P = 0.003), whereas it was similar when the forearm was vertical (7.9 ± 4.1 and 7.8 ± 4.5 min, P = 0.995). The activity of the rotator cuff muscles was greater during the position tasks (25.1 ± 10.1% maximal voluntary contraction) compared with the force tasks (15.2 ± 5.4% maximal voluntary contraction, P < 0.001) in both forearm postures. However, the rates of increase in electromyogram of the accessory muscles and mean arterial pressure were greater for the position task only when the forearm was horizontal ( P < 0.05), whereas it was similar for the elbow flexors. These findings indicate that forearm posture influences the difference in the time to failure for the two fatiguing contractions. When there was a difference between the two tasks, the task with the briefer time to failure involved greater rates of increase in accessory muscle activity and mean arterial pressure.
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Scott, B., B. Dascombe, N. Elsworthy, and J. Delaney. "The reliability of a linear position transducer to quantify measures of force and power during resistance exercise." Journal of Science and Medicine in Sport 16 (December 2013): e71. http://dx.doi.org/10.1016/j.jsams.2013.10.169.
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McNeill, Conor, C. Martyn Beaven, Daniel T. McMaster, and Nicholas Gill. "Eccentric Force-Velocity Characteristics during a Novel Squat Protocol in Trained Rugby Union Athletes—Pilot Study." Journal of Functional Morphology and Kinesiology 6, no. 2 (March 30, 2021): 32. http://dx.doi.org/10.3390/jfmk6020032.
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Eccentric strength characteristics have been shown to be important factors in physical performance. Many eccentric tests have been performed in isolation or with supramaximal loading. The purpose of this study was to investigate within- and between- session reliability of an incremental eccentric back squat protocol. Force plates and a linear position transducer captured force-time-displacement data across six loading conditions, separated by at least seven days. The reliability of eccentric specific measurements was assessed using coefficient of variation (CV), change in mean, and intraclass correlation coefficient (ICC). Eccentric peak force demonstrated good ICC (≥0.82) and TE (≤7.3%) for each load. Variables based on mean data were generally less reliable (e.g., mean rate of force development, mean force, mean velocity). This novel protocol meets acceptable levels of reliability for different eccentric-specific measurements although the extent to which these variables affect dynamic performance requires further research.
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Shin, Hyun Joo, Myung-Joon Kim, Choon-Sik Yoon, Kwanseop Lee, Kwan Sik Lee, Jong-Chul Park, Mi-Jung Lee, and Haesung Yoon. "Motion effects on the measurement of stiffness on ultrasound shear wave elastography: a moving liver fibrosis phantom study." Medical Ultrasonography 1, no. 1 (February 4, 2018): 14. http://dx.doi.org/10.11152/mu-1138.
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Aims: To evaluate the differences between shear wave velocities (SWVs) measured with ultrasound elastography during the continuous motion using liver fibrosis phantoms.Materials and methods: Elasticities were measured with convex and linear transducers of supersonic shear wave imaging (SSI) and acoustic radiation force impulse imaging (ARFI) using liver elasticity phantoms (3.0 and 16.9 kPa) at depths of 2, 3, 4, and 5 cm. Motion velocities were 30 and 60 rpm with the phantoms in an upright position on the Orbital shaker. To simulate different directional motion, the phantoms were laid on their side on the shaker. The values between moving and static status were compared, and the number of measurement failure was counted. Results: In SSI, the convex transducer was less affected by motion at 30 rpm with the 3 kPa phantom. In the higher velocity motion and in the higher stiffness phantom, most values from SSI were different comparing with static status, and there was a tendency for elasticity values to increase during movement. In ARFI, there were frequent measurement failures without stable results during the motion.Conclusions: Motion affected the measurement of elasticity differently in SSI and ARFI, according to the velocity, direction of the motion, and phantom stiffness. The convex transducer of SSI was less affected by motion in lower velocity motion and when using normal liver stiffness phantom.
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Winges, Sara A., Stephanie E. Eonta, John F. Soechting, and Martha Flanders. "Multi-Digit Control of Contact Forces During Rotation of a Hand-Held Object." Journal of Neurophysiology 99, no. 4 (April 2008): 1846–56. http://dx.doi.org/10.1152/jn.01238.2007.
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Rotation of an object held with three fingers is produced by modulation of force amplitude and direction at one or more contact points. Changes in the moment arm through which these forces act can also contribute to the modulation of the rotational moment. Therefore force amplitude and direction as well as the center of pressure on each contact surface must be carefully coordinated to produce a rotation. Because there is not a single solution, this study sought to describe consistent strategies for simple position-to-position rotations in the pitch, roll, and yaw axes. Force amplitude and direction, and center of pressure on the contact surfaces (and thus the moment arm), were measured as human subjects rotated a 420 g force-transducer instrumented object, grasped with the thumb, index and ring fingers (average movement time: 500 ms). Electromyographic (EMG) activity was recorded from five intrinsic and three extrinsic hand muscles and two wrist muscles. Principal components analysis of force and EMG revealed just two main temporal patterns: the main one followed rotational position and the secondary one had a time course that resembled that of rotational velocity. Although the task could have been accomplished by dynamic modulation of the activity of wrist muscles alone, these two main dynamic EMG patterns were seen in intrinsic hand muscles as well. In contrast to previous reports of shifting in time of the phasic activity bursts of various muscles, in this task, all EMG records were well described by just two temporal patterns, resembling the position and velocity traces.
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Hansen, Keir T., John B. Cronin, and Michael J. Newton. "The Reliability of Linear Position Transducer and Force Plate Measurement of Explosive Force–Time Variables During a Loaded Jump Squat in Elite Athletes." Journal of Strength and Conditioning Research 25, no. 5 (May 2011): 1447–56. http://dx.doi.org/10.1519/jsc.0b013e3181d85972.
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Griffith, Erin E., Tejin Yoon, and Sandra K. Hunter. "Age and load compliance alter time to task failure for a submaximal fatiguing contraction with the lower leg." Journal of Applied Physiology 108, no. 6 (June 2010): 1510–19. http://dx.doi.org/10.1152/japplphysiol.01396.2009.
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The purpose of this study was to compare the time to failure and muscle activation of young and old adults for a sustained isometric submaximal contraction with the dorsiflexor muscles when the foot was restrained to a force transducer (force-control task) compared with supporting an equivalent inertial load unrestrained in the sagittal plane (position-control task). Seventeen young (23.6 ± 6.5 yr) and 12 old (70.0 ± 5.0 yr) adults performed the force-control and position-control tasks at 30% maximal voluntary contraction (MVC) until task failure on separate days. Despite the similar load torque for each task, time to failure was longer for the force-control than position-control task (10.4 ± 4.5 vs. 8.6 ± 3.4 min, P = 0.03) for the young and old adults. The old adults, however, had a longer time to task failure than the young adults for both tasks (11.4 ± 4.4 vs. 8.1 ± 2.1 min, P = 0.01), with no interaction of age and task ( P = 0.83). The rate of increase in agonist and antagonist root-mean-square EMG, agonist EMG bursting activity, mean arterial pressure, and heart rate during the fatiguing contraction was greater for the position-control than force-control task for the young and old adults. The old adults had a less rapid rate of increase in EMG activity, fluctuations in motor output, and cardiovascular measures than the young adults for both tasks. Development of fatigue can be manipulated in young and old adults by providing greater support to the foot and less ankle compliance during daily and ergonomic tasks that require prolonged activation of the lower leg. Minimizing load compliance to one degree of freedom during a position-control task maintained the greater fatigue resistance with age for an isometric contraction.
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Pueo, Basilio, Jose J. Lopez, Jose M. Mossi, Adrian Colomer, and Jose M. Jimenez-Olmedo. "Video-Based System for Automatic Measurement of Barbell Velocity in Back Squat." Sensors 21, no. 3 (January 30, 2021): 925. http://dx.doi.org/10.3390/s21030925.
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Velocity-based training is a contemporary method used by sports coaches to prescribe the optimal loading based on the velocity of movement of a load lifted. The most employed and accurate instruments to monitor velocity are linear position transducers. Alternatively, smartphone apps compute mean velocity after each execution by manual on-screen digitizing, introducing human error. In this paper, a video-based instrument delivering unattended, real-time measures of barbell velocity with a smartphone high-speed camera has been developed. A custom image-processing algorithm allows for the detection of reference points of a multipower machine to autocalibrate and automatically track barbell markers to give real-time kinematic-derived parameters. Validity and reliability were studied by comparing the simultaneous measurement of 160 repetitions of back squat lifts executed by 20 athletes with the proposed instrument and a validated linear position transducer, used as a criterion. The video system produced practically identical range, velocity, force, and power outcomes to the criterion with low and proportional systematic bias and random errors. Our results suggest that the developed video system is a valid, reliable, and trustworthy instrument for measuring velocity and derived variables accurately with practical implications for use by coaches and practitioners.
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Ning, Dayong, Jinkai Che, Zengmeng Zhang, Hao Tian, Jiaoyi Hou, and Yongjun Gong. "Position/force control of master–slave antagonistic joint actuated by water hydraulic artificial muscles." International Journal of Advanced Robotic Systems 16, no. 3 (May 1, 2019): 172988141985398. http://dx.doi.org/10.1177/1729881419853981.
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Because of the high force–weight ratio of water hydraulic artificial muscle and its high compatibility with an underwater environment, the water hydraulic artificial muscle has received increasing attention due to its potential uses in marine engineering applications. The master–slave anthropopathic joint actuated by water hydraulic artificial muscles is light and small, and it has good maneuverability for underwater manipulators. However, the control methodologies for water hydraulic artificial muscle joint have not been thoroughly explored to date. This article introduces a master–slave control system of isomorphic artificial muscle joints. The water hydraulic artificial muscle joint acts as a slave joint working under the sea, and the pneumatic artificial muscle joint acts as a master joint that is operated by people. The rotation angle signal of the pneumatic artificial muscle joint is fed back as the input to regulate the rotation angle of the water hydraulic artificial muscle joint through a proportional–integral–derivative control. Meanwhile, the torque of the pneumatic artificial muscle joint is controlled by a proportional–integral–derivative controller based on the feedback of a two-force-transducer system in the water hydraulic artificial muscle joint as input. Therefore, the operator can control the movement and feel the load of the water hydraulic artificial muscle slave joint. Master–slave control experiments were performed, and the position/torque control results were analyzed using various loads and torque gains. This study contributes to the design and control of an anthropopathic underwater manipulator.
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Edsfeldt, S., D. Rempel, K. Kursa, E. Diao, and L. Lattanza. "In vivo flexor tendon forces generated during different rehabilitation exercises." Journal of Hand Surgery (European Volume) 40, no. 7 (June 26, 2015): 705–10. http://dx.doi.org/10.1177/1753193415591491.
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We measured in vivo forces in the flexor digitorum profundus and the flexor digitorum superficialis tendons during commonly used rehabilitation manoeuvres after flexor tendon repair by placing a buckle force transducer on the tendons of the index finger in the carpal canal during open carpal tunnel release of 12 patients. We compared peak forces for each manoeuvre with the reported strength of a flexor tendon repair. Median flexor digitorum profundus force (24 N) during isolated flexor digitorum profundus flexion and median flexor digitorum superficialis force (13 N) during isolated flexor digitorum superficialis flexion were significantly higher than during the other manoeuvres. Significantly higher median forces were observed in the flexor digitorum superficialis with the wrist at 30° flexion (6 N) compared with the neutral wrist position (5 N). Median flexor digitorum profundus forces were significantly higher during active finger flexion (6 N) compared with place and hold (3 N). Place and hold and active finger flexion with the wrist in the neutral position or tenodesis generated the lowest forces; isolated flexion of these tendons generated higher forces along the flexor tendons. Level of evidence: III (controlled trial without randomization)
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Pouderoux, P., and P. J. Kahrilas. "Function of upper esophageal sphincter during swallowing: the grabbing effect." American Journal of Physiology-Gastrointestinal and Liver Physiology 272, no. 5 (May 1, 1997): G1057—G1063. http://dx.doi.org/10.1152/ajpgi.1997.272.5.g1057.
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This study investigated deglutitive axial force developed within the pharynx, upper esophageal sphincter (UES), and cervical esophagus. Position and deglutitive excursion of the UES were determined using combined manometry and videofluoroscopy in eight healthy volunteers. Deglutitive clearing force was quantified with a force transducer to which nylon balls of 6- or 8-mm diameter were tethered and positioned within the oropharynx, hypopharynx, UES, and cervical esophagus. Axial force recordings were synchronized with videofluoroscopic imaging. Clearing force was dependent on both sphere diameter (P < 0.05) and location, with greater force exhibited in the hypopharynx and UES compared with the oropharynx and esophagus (P < 0.05). Within the UES, the onset of traction force coincided with passage of the pharyngeal clearing wave but persisted well beyond this. On videofluoroscopy, the persistent force was associated with the aboral motion of the ball caught within the UES. Force abated with gradual slippage of the UES around the ball. The force attributable to the combination of UES contraction and laryngeal descent was named the grabbing effect. The grabbing effect functions to transfer luminal contents distal to the laryngeal inlet at the end of the pharyngeal swallow, presumably acting to prevent regurgitation and/or aspiration of swallowed material.
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Xu, Yangsheng, and R. P. Paul. "Robotic Instrumented Complaint Wrist." Journal of Engineering for Industry 114, no. 1 (February 1, 1992): 120–23. http://dx.doi.org/10.1115/1.2899749.
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A robotic complaint wrist which combines a passive compliance device and a displacement sensor has been developed and tested. The device provides the necessary flexibility to accommodate transitions between the position control and force control modes, and avoid large impact forces as a robot makes contact with parts, as well as correct positioning errors and allow the relaxation of tolerances in assembly and manufacturing operations. The device installed between a robot arm and end-effector is composed of two parts: a passive compliance device and a sensing mechanism. The passive compliance is provided by a rubber structure; its configuration can be arranged to yield the desired stiffness ratio along and about each axis. The sensing mechanism consists of a six-joint serial linkage with a transducer at each point. The measured deflection is used to actively control the contact forces and compensate for the positioning error during motion and contact. In this paper, the design features of two prototypes of the device are described. A systematic hybrid position/force control scheme incorporating the device is presented.
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Yeap, Joo Seng, Alison H. McGregor, Keith Humphries, and Andrew L. Wallace. "ULTRASONIC EVALUATION OF ANTERIOR SHOULDER TRANSLATION IN NORMAL SHOULDERS." Journal of Musculoskeletal Research 07, no. 02 (June 2003): 125–34. http://dx.doi.org/10.1142/s0218957703001058.
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Anterior translation in the right shoulders of 23 volunteers was evaluated using ultrasound from an anterior approach with a 10 MHz, 6 cm wide linear transducer. A translatory force of 90 N was used to translate the humeral head in the adduction and internal rotation position, while a translatory force of 60 N was used in the more clinically relevant position of 90° abduction and external rotation position. The overall intra-observer coefficients of variation ranged from 0–13.0% (mean 3.8 ± 2.5%) for examiner I and 0.5–20.9% (mean 5.1 ± 3.9%) for examiner II. The overall inter-observer variation ranged from 0–29.8% (mean 9.3 ± 7.3%). The anterior translation of the humeral head in adduction and internal rotation following 90 N displacement force ranged from -2.6 to 12.9 mm (mean 2.1 ± 3.1 mm) for examiner I and from -4.1 to 4.7 mm (mean 1.1 ± 2.2 mm) for examiner II. The anterior translation of the humeral head in abduction and external rotation following 60 N displacement force ranged from -3.3 to 3.7 mm (mean 0.3 ± 1.9 mm) for examiner I and from -8.3 mm to 4.5 mm (mean -0.7 ± 2.6 mm) for examiner II. The intra-class correlation coefficients (r) for the measured anterior translation between the two examiners for the 2 positions were 0.029 and -0.058 respectively. We concluded that the inter-observer coefficient of variation remained excessive and the agreement in the measured anterior translation between the two examiners was poor. The finding of negative values in the measured anterior translation despite the use of 90 N and 60 N translatory force raises further concerns about the prospective clinical use of this technique at the present moment.
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ERAK, S., R. DAY, and A. WANG. "The Role of Supinator in the Pathogenesis of Chronic Lateral Elbow Pain: A Biomechanical Study." Journal of Hand Surgery 29, no. 5 (October 2004): 461–64. http://dx.doi.org/10.1016/j.jhsb.2004.06.001.
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The relative contributions of the forearm extensors to the tensile force at the lateral epicondyle were examined by implanting a force transducer in the common extensor tendon of four soft fixed cadaver elbows and sequentially stretching each muscle arising from the lateral epicondye. Extensor carpi radialis brevis and extensor digitorum communis produced the largest increases while the superficial head of supinator produced a moderate increase in tensile force in the common extensor tendon. Extensor carpi radialis longus and extensor carpi ulnaris had no significant effect. Radial tunnel pressure was measured using a balloon catheter in a separate study of five cadaver elbows. Radial tunnel pressure increased on moving the wrist from neutral to a flexion–pronation position. This positional rise in pressure was reduced by supinator musculotendinous lengthening (77%) while lengthening of the extensor carpi radialis brevis and extensor digitorum communis had no effect. This study demonstrates a biomechanical basis for the superficial head of supinator in the aetiology of both lateral epicondylitis and radial tunnel syndrome.
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Leung, Anderson, and Shahram Payandeh. "Application of adaptive neural network to localization of objects using pressure array transducer." Robotica 14, no. 4 (July 1996): 407–14. http://dx.doi.org/10.1017/s0263574700019809.
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SUMMARYPattern recognition and object localization, using various sensors such as vision and tactile sensors, are two important areas of research in the application of robotic systems. This paper demonstrates the feasibility of using some relatively inexpensive array of pressure sensors and a neural network approach to achieve object localization and pattern recognition. The sensors that are used are force sensing resistors (FSRs), more specifically, a 16 x 16 array of FSRs. Because of the nonlinearity associated with a FSR, three possible approaches for gathering output from the sensor array are used. The neural network that is used consists of two 2-layer counterpropagation networks (CPNs). One of the CPNs is trained to recognize contact signatures of different objects placed on a fixed reference position on the sensor array.
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Young, Kieran P., G. Gregory Haff, Robert U. Newton, Tim J. Gabbett, and Jeremy M. Sheppard. "Assessment and Monitoring of Ballistic and Maximal Upper-Body Strength Qualities in Athletes." International Journal of Sports Physiology and Performance 10, no. 2 (March 2015): 232–37. http://dx.doi.org/10.1123/ijspp.2014-0073.
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Purpose:To evaluate whether the dynamic strength index (DSI: ballistic peak force/isometric peak force) could be effectively used to guide specific training interventions and detect training-induced changes in maximal and ballistic strength.Methods:Twenty-four elite male athletes were assessed in the isometric bench press and a 45% 1-repetition-maximum (1RM) ballistic bench throw using a force plate and linear position transducer. The DSI was calculated using the peak force values obtained during the ballistic bench throw and isometric bench press. Athletes were then allocated into 2 groups as matched pairs based on their DSI and strength in the 1RM bench press. Over the 5 wk of training, athletes performed either high-load (80–100% 1RM) bench press or moderate-load (40–55% 1RM) ballistic bench throws.Results:The DSI was sensitive to disparate training methods, with the bench-press group increasing isometric bench-press peak force (P = .035, 91% likely), and the ballistic-bench-throw group increasing bench-throw peak force to a greater extent (P ≤ .001, 83% likely). A significant increase (P ≤ .001, 93% likely) in the DSI was observed for both groups.Conclusions:The DSI can be used to guide specific training interventions and can detect training-induced changes in isometric bench-press and ballistic bench-throw peak force over periods as short as 5 wk.
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Li, Jing, Lawrence E. M. Grierson, Mary X. Wu, Ronny Breuer, and Heather Carnahan. "Perceptual Motor Features of Expert Acupuncture Lifting-Thrusting Skills." Acupuncture in Medicine 31, no. 2 (June 2013): 172–77. http://dx.doi.org/10.1136/acupmed-2012-010265.
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Background Little is known with regard to how acupuncture skills are optimally taught, learnt and evaluated despite clear evidence that technical skill acquisition is important to trainee success in health professions. Objectives This study reports an investigation of the sensorimotor aspects of the acupuncture lifting-thrusting skill in order to highlight the important kinematic and kinetic features of the action. The study also explores the role of perceptual acuity in accurate acupuncture performance. Methods Twelve novice and 12 expert acupuncturists watched a standardised video demonstrating the mild reinforcing and reducing technique of lifting-thrusting on an acupuncture point and then performed 10 trials of the technique on an artificial skin pad mounted on a six-axis force transducer with an infrared light-emitting diode affixed to the index finger of their dominant hand. The force transducer measured the force applied by participants as they needled the acupuncture point while an optoelectric camera measured the position of the diode. Subsequently, the participants engaged in two tests of general perceptual acuity. Results Repeated measures analyses of variance indicated that experts are more consistent in their trial-by-trial amplitude (p=0.03) and lifting-thrusting velocity (p=0.029) than novices. Measures of perceptual acuity revealed no differences between novices and experts. Conclusions Movement amplitude and velocity consistency are the action features of the mild reinforcing and reducing lifting-thrusting skill that differentiate the performances of experts from novices. The acquisition of acupuncture expertise is a function of extended practice rather than any inherent perceptual ability.
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Young, Kieran P., G. Gregory Haff, Robert U. Newton, and Jeremy M. Sheppard. "Reliability of a Novel Testing Protocol to Assess Upper-Body Strength Qualities in Elite Athletes." International Journal of Sports Physiology and Performance 9, no. 5 (September 2014): 871–75. http://dx.doi.org/10.1123/ijspp.2013-0332.
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Purpose:The purpose of this study was to evaluate the reliability of an isometric-bench-press (IBP) test performed across 4 elbow angles and a ballistic bench throw (BBT) using a relative load, as well as evaluating the reliability of the dynamic strength index (DSI: BBT peak force/IBP peak force).Methods:Twenty-four elite male athletes performed the IBP and a 45% 1-repetition-maximum BBT on 2 separate days with 48 h between testing occasions. Peak force, peak power, peak velocity, peak displacement, and peak rate of force development (PRFD) were assessed using a force plate and linear position transducer. Reliability was assessed by intraclass correlation (ICC), coefficient of variation (%CV) and typical error.Results:Performance measures in the BBT, such as peak force, peak velocity, peak power, and peak displacement, were considered reliable (ICC = .85–.92, %CV = 1.7–3.3), while PRFD was not (ICC = .43, %CV = 4.1). Similarly, for the IBP, peak force across all angles was considered reliable (ICC = .89–.97, %CV = 1.2–1.6), while PRFD was not (ICC = .56–.65, %CV = 0.5–7.6). The DSI was also reliable (ICC = .93, %CV = 3.5).Conclusions:Performance measures such as peak force in the IBP and BBT are reliable when assessing upper-body pressing-strength qualities in elite male athletes. Furthermore, the DSI is reliable and could potentially be used to detect qualities of relative deficiency and guide specific training interventions.
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Pérez-Castilla, Alejandro, Antonio Piepoli, Gabriel Garrido-Blanca, Gabriel Delgado-García, Carlos Balsalobre-Fernández, and Amador García-Ramos. "Precision of 7 Commercially Available Devices for Predicting Bench-Press 1-Repetition Maximum From the Individual Load–Velocity Relationship." International Journal of Sports Physiology and Performance 14, no. 10 (November 1, 2019): 1442–46. http://dx.doi.org/10.1123/ijspp.2018-0801.
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Objective: To compare the accuracy of different devices to predict the bench-press 1-repetition maximum (1RM) from the individual load–velocity relationship modeled through the multiple- and 2-point methods. Methods: Eleven men performed an incremental test on a Smith machine against 5 loads (45–55–65–75–85%1RM), followed by 1RM attempts. The mean velocity was simultaneously measured by 1 linear velocity transducer (T-Force), 2 linear position transducers (Chronojump and Speed4Lift), 1 camera-based optoelectronic system (Velowin), 2 inertial measurement units (PUSH Band and Beast Sensor), and 1 smartphone application (My Lift). The velocity recorded at the 5 loads (45–55–65–75–85%1RM), or only at the 2 most distant loads (45–85%1RM), was considered for the multiple- and 2-point methods, respectively. Results: An acceptable and comparable accuracy in the estimation of the 1RM was observed for the T-Force, Chronojump, Speed4Lift, Velowin, and My Lift when using both the multiple- and 2-point methods (effect size ≤ 0.40; Pearson correlation coefficient [r] ≥ .94; standard error of the estimate [SEE] ≤ 4.46 kg), whereas the accuracy of the PUSH (effect size = 0.70–0.83; r = .93–.94; SEE = 4.45–4.80 kg), and especially the Beast Sensor (effect size = 0.36–0.84; r = .50–.68; SEE = 9.44–11.2 kg), was lower. Conclusions: These results highlight that the accuracy of 1RM prediction methods based on movement velocity is device dependent, with the inertial measurement units providing the least accurate estimate of the 1RM.
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Herron, Todd J., F. Steven Korte, and Kerry S. McDonald. "Loaded shortening and power output in cardiac myocytes are dependent on myosin heavy chain isoform expression." American Journal of Physiology-Heart and Circulatory Physiology 281, no. 3 (September 1, 2001): H1217—H1222. http://dx.doi.org/10.1152/ajpheart.2001.281.3.h1217.
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The purpose of this study was to examine the role of myosin heavy chain (MHC) in determining loaded shortening velocities and power output in cardiac myocytes. Cardiac myocytes were obtained from euthyroid rats that expressed α-MHC or from thyroidectomized rats that expressed β-MHC. Skinned myocytes were attached to a force transducer and a position motor, and isotonic shortening velocities were measured at several loads during steady-state maximal Ca2+ activation (PpCa4.5). MHC expression was determined after mechanical measurements using SDS-PAGE. Both α-MHC and β-MHC myocytes generated similar maximal Ca2+-activated force, but α-MHC myocytes shortened faster at all loads and generated ∼170% greater peak normalized power output. Additionally, the curvature of force-velocity relationships was less, and therefore the relative load optimal for power output (Fopt) was greater in α-MHC myocytes. Fopt was 0.31 ± 0.03 PpCa4.5 and 0.20 ± 0.06 PpCa4.5 for α-MHC and β-MHC myocytes, respectively. These results indicate that MHC expression is a primary determinant of the shape of force-velocity relationships, velocity of loaded shortening, and overall power output-generating capacity of individual cardiac myocytes.
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Nicol, Caroline, and Paavo V. Komi. "Quantification of Achilles Tendon Force Enhancement by Passively Induced Dorsiflexion Stretches." Journal of Applied Biomechanics 15, no. 3 (August 1999): 221–32. http://dx.doi.org/10.1123/jab.15.3.221.
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Magnitude of the reflex contribution to force enhancement was investigated in vivo during passive stretches of the Achilles tendon (AT) of one female subject. Thirty passive (5 × 6) dorsiflexions were induced by a motorized ankle ergometer. Achilles tendon force (ATF) was sensed by a buckle transducer applied surgically around the right AT. Single passive stretches resulted in a low but rather linear ATF increase in the absence of EMG (surface electrodes) activity. In the presence of reflexes, a clear ATF enhancement occurred 13–15 ms after the beginning of the EMG reflex responses. In double dorsiflexions at either 1.2 or 1.9 rad · s-1, which were separated by a maintained stretched position of either 40 or 90 ms, the first stretch resulted in initial linear ATF increase, followed by an additional force enhancement during the plateau phase. This reflexly induced increase represented 94 ± 4 N and 184 ± 1 N, respectively, for the 40 and the 90 ms plateaus, corresponding to 210 ± 85% and 486 ± 177% enhancements as compared to the first passive stretch effect. The results suggest further that timing of the stretch during the twitch response influences the magnitude and rate of force potentiation.
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Jeger-Madiot, Nathan, Xavier Mousset, Chloé Dupuis, Lucile Rabiet, Mauricio Hoyos, Jean-Michel Peyrin, and Jean-Luc Aider. "Controlling the force and the position of acoustic traps with a tunable acoustofluidic chip: Application to spheroid manipulations." Journal of the Acoustical Society of America 151, no. 6 (June 2022): 4165–79. http://dx.doi.org/10.1121/10.0011464.
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A multi-node acoustofluidic chip working on a broadband spectrum and beyond the resonance is designed for cell manipulations. A simple one-dimensional (1D) multi-layer model is used to describe the stationary standing waves generated inside a cavity. The transmissions and reflections of the acoustic wave through the different layers and interfaces lead to the creation of pressure nodes away from the resonance condition. A transparent cavity and a broadband ultrasonic transducer allow the measurement of the acoustic energy over a wide frequency range using particle image velocimetry measurements and the relation between acoustic energy and the particles velocity. The automation of the setup allows the acquisition over a large spectrum with a high frequency definition. The results show a wide continuous operating range for the acoustofluidic chip, which compares well with the 1D model. The variation of the acoustic radiation force when varying the frequency can be compensated to ensure a constant amplitude for the ARF. This approach is finally applied to mesenchymal stem cell (MCS) spheroids cultured in acoustic levitation. The MSC spheroids can be moved and merged just by varying the acoustic frequency. This approach opens the path to various acoustic manipulations and to complex 3D tissue engineering in acoustic levitation.
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Takasaki, Masaya, Shota Chino, Yasuhiro Kato, Yuji Ishino, and Takeshi Mizuno. "Actuation Force Measurement Mechanism for Non-Contact Ultrasonic Suspension." Key Engineering Materials 523-524 (November 2012): 727–32. http://dx.doi.org/10.4028/www.scientific.net/kem.523-524.727.
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In near-field levitation, an object can be levitated vertically upward above vibrating surface of an ultrasonic transducer. In this case, a repulsive force acts on the object. On the other hand, it has been reported that a minute object can be suspended vertically downward under the vibrating surface with a small gap in the air. We call this phenomenon ultrasonic suspension. Under the suspension, an attractive force acts on the object. When an object is suspended, there is restoring force, which pulls the object to the center of the vibrating surface. Our aim is to characterize the actuation forces under the suspension. Simultaneous measurement of vertical and horizontal actuation forces is required. A servo type measuring mechanism was proposed. A 1 DOF mechanism with a cantilever and a voice coil motor (VCM) was fabricated as a prototype. The prototype was calibrated and utilized for measurement of vertical actuation force. The result showed enough accuracy and repeatability. Then, a 2 DOF actuation force measurement mechanism was fabricated. The mechanism was consisted of a base to fix the object and two thin wires to support the base. Position of the base was controlled by three VCMs based on PID control. The ultrasonic suspension actuation forces were characterized successfully.
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Wheeler, Jeffrey B., Robert J. Gregor, and Jeffrey P. Broker. "A Dual Piezoelectric Bicycle Pedal with Multiple Shoe/Pedal Interface Compatibility." International Journal of Sport Biomechanics 8, no. 3 (August 1992): 251–58. http://dx.doi.org/10.1123/ijsb.8.3.251.
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In response to the popularity of clipless bicycle pedals with float designs, an instrumented force pedal system with multicompatibility for different shoe/pedal interfaces is presented. A dual piezoelectric element pedal has been modified for use with popular clipless pedal interfaces. The dual transducer arrangement permits measurement of three components of uniaxial load, location of the applied load, and calculation of the moment Mz about an axis through the position of the applied load and orthogonal to the pedal surface. Quantification of lower extremity kinetics using float feature pedals and the investigation of the pathomechanics of lower extremity cycling overuse injuries, especially knee injuries, is warranted. Qualitative descriptions of lower extremity pathomechanics related to overuse injuries have suggested that foot constraint may induce undesirable knee kinematics and kinetics. The instrumented force pedal system described here permits a comparison between pedal kinematics and kinetics of popular shoe/pedal interfaces with varying degrees of float allowance.
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Moura, Isabela Silva Gomes, Leonardo Silva Gomes Kamezawa, Eduardo Galera Da Silva, Jose Benedito Oliveira Amorim, Guilherme Schmitt De Andrade, and Clovis Pagani. "Masticatory force and electromyographic activity of the mandibular elevators muscles in different rehabilitation treatments." Brazilian Dental Science 22, no. 3 (July 30, 2019): 387–94. http://dx.doi.org/10.14295/bds.2019.v22i3.1759.
Full textAbstract:
The masticatory function is one of the most complex neuropsychological mechanisms in human motor performance and it depends on several factors, such as bite force, muscle coordination, morphology, and number of teeth in occlusion. Purpose: to evaluate the influence of different rehabilitation treatments such as complete and partial dentures, masticatory forces, and the dynamics of mandibular elevator muscles. Material and Methods: the maximum bite force (force transducer) and electrical activity (superficial electromyography) associated with the masseter and temporal muscles were quantified. These factors were evaluated at rest position and isometric contraction. The data were subjected to descriptive statistics and compared based on the experimental groups, through ANOVA and Tukey’s tests. Results: for bite force, the ANOVA test showed statistical difference between groups and Tukey’s test showed that the force measured in the removable partial dentures group was 44.75% lower than that of the control group, while for complete denture wearers, there was a reduction of 74.4% in bite force in relation to the control group. For electromyographic activity, there was no statistical difference between groups. Pearson’s correlation test (α=5%) showed positive correlation between the variables of bite force and electromyographic activity only for the control group. Conclusion: it was concluded that the loss of dental elements and their replacement with either partial or complete dentures has a great influence on bite force and electromyographic activity of the masseter and temporal muscles.
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Hinken, Aaron C., F. Steven Korte, and Kerry S. McDonald. "Porcine cardiac myocyte power output is increased after chronic exercise training." Journal of Applied Physiology 101, no. 1 (July 2006): 40–46. http://dx.doi.org/10.1152/japplphysiol.00798.2005.
Full textAbstract:
Chronic exercise training increases the functional capacity of the heart, perhaps by increased myocyte contractile function, as has been observed in rodent exercise models. We examined whether cardiac myocyte function is enhanced after chronic exercise training in Yucatan miniature swine, whose heart characteristics are similar to humans. Animals were designated as either sedentary (Sed), i.e., cage confined, or exercise trained (Ex), i.e., underwent 16–20 wk of progressive treadmill training. Exercise training efficacy was shown with significantly increased heart weight-to-body weight ratios, skeletal muscle citrate synthase activity, and exercise tolerance. Force-velocity properties were measured by attaching skinned cardiac myocytes between a force transducer and position motor, and shortening velocities were measured over a range of loads during maximal Ca2+ activation. Myocytes ( n = 9) from nine Ex pigs had comparable force production but a ∼30% increase in peak power output compared with myocytes ( n = 8) from eight Sed. Interestingly, Ex myofibrillar samples also had higher baseline PKA-induced phosphorylation levels of cardiac troponin I, which may contribute to the increase in power. Overall, these results suggest that enhanced power-generating capacity of porcine cardiac myofibrils contributes to improved cardiac function after chronic exercise training.
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Kim, Dong-Hyeon, and Choon-Man Lee. "Development of variable preload system for machine tool spindle using giant magnetostrictive material Terfenol-D actuator." Journal of Intelligent Material Systems and Structures 31, no. 20 (June 29, 2020): 2304–11. http://dx.doi.org/10.1177/1045389x20935573.
Full textAbstract:
Applying a bearing preload of machine tool spindle produces positive effects, including increased stiffness, rotation noise reduction, increase in shaft precision, position adjustment during operation, and prevention of rolling element resonance and rotating slip, along with a significant extension of the bearing lifespan. A variable preload technique is a method that improves the bearing performance by appropriately varying the preload applied to the bearing according to the spindle rotation speed and machining condition. In this study, a novel variable preload method utilizing a Terfenol-D actuator has greater power and more displacement and force than those of other transducer materials such as piezo elements or nickel alloys. Terfenol-D has greater power and more displacement and more force. A prototype of a spindle for the variable preload system using Terfenol-D was fabricated, and the axial force and displacement of the bearing were measured during a running experiment. In order to assess whether the proposed variable preload device can effectively apply preloading to the bearing, a comparative analysis was conducted between the theoretical and empirically obtained values of the bearing axial direction displacement. Through the comparative analysis, the real applicability of the proposed structure was confirmed.
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Hinken, Aaron C., and Kerry S. McDonald. "Inorganic phosphate speeds loaded shortening in rat skinned cardiac myocytes." American Journal of Physiology-Cell Physiology 287, no. 2 (August 2004): C500—C507. http://dx.doi.org/10.1152/ajpcell.00049.2004.
Full textAbstract:
Force generation in striated muscle is coupled with inorganic phosphate (Pi) release from myosin, because force falls with increasing Pi concentration ([Pi]). However, it is unclear which steps in the cross-bridge cycle limit loaded shortening and power output. We examined the role of Pi in determining force, unloaded and loaded shortening, power output, and rate of force development in rat skinned cardiac myocytes to discern which step in the cross-bridge cycle limits loaded shortening. Myocytes ( n = 6) were attached between a force transducer and position motor, and contractile properties were measured over a range of loads during maximal Ca2+ activation. Addition of 5 mM Pi had no effect on maximal unloaded shortening velocity ( Vo) (control 1.83 ± 0.75, 5 mM added Pi 1.75 ± 0.58 muscle lengths/s; n = 6). Conversely, addition of 2.5, 5, and 10 mM Pi progressively decreased force but resulted in faster loaded shortening and greater power output (when normalized for the decrease in force) at all loads greater than ∼10% isometric force. Peak normalized power output increased 16% with 2.5 mM added Pi and further increased to a plateau of ∼35% with 5 and 10 mM added Pi. Interestingly, the rate constant of force redevelopment ( ktr) progressively increased from 0 to 10 mM added Pi, with ktr ∼360% greater at 10 mM than at 0 mM added Pi. Overall, these results suggest that the Pi release step in the cross-bridge cycle is rate limiting for determining shortening velocity and power output at intermediate and high relative loads in cardiac myocytes.