Triaxial Force Research Articles

How Aging Affects Grasping Behavior and Pull Strength in Captive Gray Mouse Lemurs (Microcebus murinus)

Prehension is essential for animal survival and fitness. It is involved in locomotion and feeding behavior and subject to physical and physiological constraints. Studies of prehension in primates have explored the importance of food properties and of the environment, but aging has rarely been studied although prehensile capacity may deteriorate with age in humans. To test the hypothesis that aging affects grasping abilities and to reveal possible behavioral adaptations to this, we quantified behavioral grasping strategies and pull strength in 10 young adult (2–3 yr old) and 10 aged (7–8 yr old) gray mouse lemurs (Microcebus murinus). We assessed grasping strategies in an experimental cage by quantifying grip types used to grasp static and mobile foods. We measured strength using a Kistler triaxial force platform. Our results show that 1) mobile and static foods affected individuals of different ages in similar ways; 2) older individuals used more mouth grasps than young ones; 3) aged individuals made twice as many attempts as young ones when grasping mobile food items but this difference was not significant; and 4) there were no differences in hand grip strength between age classes but young individuals showed a higher foot pull strength compared to old ones. These data suggest that the observed differences in behavior may be due to a decrease in foot grip strength, which in turn influences stability on narrow branches, forcing animals to use their hands to maintain stability and preventing them from using their hands for food-related tasks.

Accuracy evaluation of a method to partition ground reaction force and center of pressure in cane-assisted gait using an instrumented cane with a triaxial force sensor

Clarifying the biomechanics of cane-assisted gait in elderly individuals and patients with gait disorders is important for developing better therapeutic interventions in the fields of rehabilitation and orthopedics. However, if the foot and the cane in the ipsilateral hand are placed on the same force plate simultaneously, the force plate cannot separate the forces as it records the sum of the forces. To overcome this indeterminacy problem of the ground reaction force (GRF) and the center of pressure (COP) in cane-assisted gait analysis, a method to partition the GRF and COP using an instrumented cane with a force transducer has been proposed. However, the accuracy and precision of the estimated GRF and COP has not been evaluated previously. We therefore reestablished a framework to partition the foot and cane forces during walking using an instrumented cane with a triaxial force sensor and evaluated the accuracy and precision of the method using a force plate array. Cane-assisted gait of healthy adults and hemiplegic patients were measured. Mean accuracy and precision associated with the GRF and COP measurements were approximately 0.4±1.4N and 0.2±2.7mm, respectively, indicating that the separations of the GRF and COP were sufficiently accurate for kinetic gait analysis. Although some methodological limitations certainly apply, this system will serve as a useful tool for improved therapeutic interventions.

Triaxial loading device for reliability tests of three-axis machine tools

Abstract This paper presents a triaxial loading device (TLD), which can apply a triaxial force on the spindle of a three-axis machine tool that is executing a 3-degree-of-freedon feeding motion, aiming at simulating cutting forces applied on the spindle in a machining process. A prototype was fabricated and its kinematics and dynamics were analyzed. An explicit force control system was designed based on a fuzzy proportional-integral (PI) controller, integrating a force and a position feedforward. The effectiveness of the control system was evaluated; results illustrate that the fuzzy PI controller reduces the rising time and overshoots, and the force and the position feedforward eliminate the hysteresis and following errors caused by unknown feeding motions, respectively. Loading experiments were conducted to test the dynamic loading capacity of the TLD. The experimental results illustrate that the device is capable to add a triaxial force, which tracks a reference force with acceptable errors, on a spatially-moving spindle with random trajectories in real time. The TLD can simulate the cutting forces that the spindle encounters in real machining process and provides an efficient and economical loading approach that avoids a costly long-term cutting for the reliability tests of three-axis machine tools.

Finger forces in fastball baseball pitching

Forces imparted by the fingers onto a baseball are the final, critical aspects for pitching, however these forces have not been quantified previously as no biomechanical technology was available. In this study, an instrumented baseball was developed for direct measurement of ball reaction force by individual fingers and used to provide fundamental information on the forces during a fastball pitch. A tri-axial force transducer with a cable having an easily-detachable connector were installed in an official baseball. Data were collected from 11 pitchers who placed the fingertip of their index, middle, ring, or thumb on the transducer, and threw four-seam fastballs to a target cage from a flat mound. For the index and middle fingers, resultant ball reaction force exhibited a bimodal pattern with initial and second peaks at 38–39ms and 6–7ms before ball release, and their amplitudes were around 97N each. The ring finger and thumb produced single-peak forces of approximately 50 and 83N, respectively. Shear forces for the index and middle fingers formed distinct peak at 4–5ms before release, and the peaks summed to 102N; a kinetic source for backspin on the ball. An additional experiment with submaximal pitching effort showed a linear relationship of peak forces with ball velocity. The peak ball reaction force for fastballs exceeded 80% of maximum finger strength measured, suggesting that strengthening of the distal muscles is important both for enhancing performance and for avoiding injuries.

Biomechanical Comparison of Loaded Countermovement Jumps on Land and in Water

Compared with land-based exercise, researchers have observed that when individuals undergo aquatic exercise and rehabilitation programs, they achieve similar, if not greater, improvements in physical function. PURPOSE: To evaluate the mechanical specificity of jumping movements performed in partial water immersion versus land using conditions of light external load, with a combined kinetic and kinematic analysis. METHODS: Twenty young males and twenty-four NCAA division I women’s soccer and gymnastics athletes were asked to perform unloaded and loaded (adding 10, 20, and 30% BW with weighted vest) countermovement jumps on land and in partial water immersion. Kinetic and kinematic measures of jump performance were obtained using a tri-axial force platform and two dimensional videography, respectively. RESULTS: Compared to land, peak and mean mechanical power outputs (W), on average, were 88% (8919±3744W vs. 4734±1418W) and 81% (3640±1807W vs. 2011±736W) greater for jumps performed in water, respectively. While most kinematic differences were small, peak dorsiflexion velocity was, on average, 688% faster (44±39°/s vs. 5.6±5.4°/s; p<0.001) for jumps performed in the water and tended to model similarly with measures of mechanical power and amortization rate. In water, the addition of light, external loading was associated with an average decrease in bodyweight normalized peak and mean mechanical power of 23.6±2.7% and 23.8±1.9%, respectively. On land, the addition of load was associated with an 8.7±2.3% and 10.5±4.4% decrease in bodyweight normalized peak and mean mechanical power, respectively. CONCLUSIONS: Buoyancy appears to alters movement strategies at amortization, which may provide a unique stimulus for training the stretch-shortening cycle contribution to jump performance. The combination of fluid resistance and buoyancy are likely responsible for previously reported improvements in athletic performance and functional mobility.

Biomechanical Comparison Of Countermovement Jumps On Land And In Water

The use of a reduced impact, aquatic environment for physical activity and rehabilitation in older adults has become a focus of recent literature. PURPOSE The present study sought to evaluate the mechanical specificity of countermovement jumps performed on land and in water in older adults. METHODS Fifty-six young (22.0±3.9years) adults and twelve healthy older (57.3±4.4yr) adults were asked to perform maximal countermovement jumps on land and in chest-deep water. Kinetic and kinematic measures of jump performance were obtained using a tri-axial force platform and two dimensional videography, respectively. RESULTS As expected, peak (PP) and mean mechanical power (MP) outputs were greater (p<.001) for jumps performed by young vs older adults (PP:7322±4035W;MP:3049±1771W) and for jumps performed by all subjects in water (PP:9387±3981W;MP:3781±1864W) vs land. Compared to young adults, older adults experienced less of an increase in bodyweight normalized PP and MP for jumps performed in water vs land (p<0.05). Peak movement velocities in older adults tended to be slower, with older adults spending 55% greater time in body unweighting. Compared to land, unweighting time increased more in the water for older adults (Land: 0.5±0.3s;Water:1.2±0.7s) than young adults (Land:0.4±0.1s;Water:0.7±0.2s). Across ages, amortization rate was 26% greater for jumps performed in water and, in comparison with younger adults, amortization time in older adults was 20% longer in duration. A 1444% increase in peak dorsiflexion velocity for jumps performed in water (66±34°/s vs. 4±7°/s), suggests that loading strategy during amortization is likely unique from land-based jumping. CONCLUSION The aquatic environment produces jumping movements that are mechanically distinct from jumping movements performed on land. The results of the present study suggest that jumping in an aquatic environment may be beneficial in older adults training to improve mechanical power output and lower-extremity neuromuscular function.

3軸力センサによる甲状腺内のしこりの硬さ計測

In this study, we report on hardness and size measurement of lump in thyroid using MEMS triaxial force sensor. We pushed triaxial force sensor to the model of thyroid and measured reactive force. The local maximums of shear force measured at the edges of the lump were 1.35N and 1.54N, respectively. The coefficient of correlation between the size of lump and the distance of local maximum points was 0.981. Since the coefficient of correlation was high, we could estimate the size of lump. The normal force measured by triaxial force sensor increased with the size and the hardness of lump. We calculated the increasing rate of normal force with respect to the size of lump. The coefficient of correlation between the increasing rate and Young's modulus of the lump was 0.996. Since the coefficient of correlation was high, we could estimate Young's modulus with average error of 0.246 kPa.

MRI-compatible triaxial force sensor with enclosed liquid using pressure transmission

MRI-compatible triaxial force sensor with enclosed liquid using pressure transmission

Blood pressure pulse wave measuring device with function to reduce the influence of body motion by triaxial force sensor

Blood pressure pulse wave measuring device with function to reduce the influence of body motion by triaxial force sensor

MEMS-Based Flexible Force Sensor for Tri-Axial Catheter Contact Force Measurement.

Atrial fibrillation (AFib) is a significant healthcare problem caused by the uneven and rapid discharge of electrical signals from pulmonary veins (PVs). The technique of radiofrequency (RF) ablation can block these abnormal electrical signals by ablating myocardial sleeves inside PVs. Catheter contact force measurement during RF ablation can reduce the rate of AFib recurrence, since it helps to determine effective contact of the catheter with the tissue, thereby resulting in effective power delivery for ablation. This paper presents the development of a three-dimensional (3D) force sensor to provide the real-time measurement of tri-axial catheter contact force. The 3D force sensor consists of a plastic cubic bead and five flexible force sensors. Each flexible force sensor was made of a PEDOT:PSS strain gauge and a PDMS bump on a flexible PDMS substrate. Calibration results show that the fabricated sensor has a linear response in the force range required for RF ablation. To evaluate its working performance, the fabricated sensor was pressed against gelatin tissue by a micromanipulator and also integrated on a catheter tip to test it within deionized water flow. Both experiments simulated the ventricular environment and proved the validity of applying the 3D force sensor in RF ablation.

Identification of Object Dynamics Using Hand Worn Motion and Force Sensors.

Emerging microelectromechanical system (MEMS)-based sensors become much more applicable for on-body measurement purposes lately. Especially, the development of a finger tip-sized tri-axial force sensor gives the opportunity to measure interaction forces between the human hand and environmental objects. We have developed a new prototype device that allows simultaneous 3D force and movement measurements at the finger and thumb tips. The combination of interaction forces and movements makes it possible to identify the dynamical characteristics of the object being handled by the hand. With this device attached to the hand, a subject manipulated mass and spring objects under varying conditions. We were able to identify and estimate the weight of two physical mass objects (0.44 kg: and 0.28 kg: ) and the spring constant of a physical spring object (). The system is a first attempt to quantify the interactions of the hand with the environment and has many potential applications in rehabilitation, ergonomics and sports.

High‐sensitivity microelectromechanical systems‐based tri‐axis force sensor for monitoring cellular traction force

A high-sensitivity tri-axis force sensor designed to measure the traction force of a single cell is reported. The developed sensor consists of a micropillar that is supported by a cross-shaped Si structure and a double-layer photoresist cap. The piezoresistors formed on the Si structure allow for the simultaneous measurement of the normal and shear forces acting on the micropillar. Moreover, the cap prevents the cells from contacting the Si structure, which is not desirable when measuring the force acting on the micropillar. The effect of the culture medium on the impedance of the sensor and the noise level of the measurement circuit was evaluated. The temperature effect was compensated using a piezoresistor that does not possess a through-hole underneath. For measurement, inside a culture medium, the resolution of the sensor obtained from the standard deviations of the measured signals was less than 2 nN. Finally, it was demonstrated that the sensor is capable of measuring the traction force in three dimensions generated by an osteosarcoma cell when it detaches from the micropillar under trypsin treatment.

Analysis of tri-axial force and vibration sensors for detection of failure criterion in deep twist drilling process

Deep twist drilling technique with length per diameter ratio of more than 10 is widely used, especially in tool and die industries. This technique can improve the quality and production of drilling products by increasing feed rate and can shorten the machining time. The limitation in this process is premature tool breakage due to tool wear, chip clogging, and tool failures. In this study, deep drilling process was analyzed via cutting force and vibrations by using three-axis force dynamometer and accelerometer sensors to detect failure criteria. Deep twist drills were analyzed through cutting parameters, such as cutting speeds, feeds, and depth of cut. The effects on the tool condition during cutting operations were measured by three-axis data of vibrations and force sensors and then analyzed in time and frequency domain. Results indicated that both sensors are capable of monitoring tool conditions. However, data produced by vibration sensors are more appropriate to detect initial conditions before tool failure. Thus, monitoring tool conditions in three axes can lead to precise data and earlier detection in the y axis instead of in the z axis. Cutting condition analysis found that cutting speed and feeds of more than 50 m/min and 0.25 mm/rev, respectively, result in tool failures under safety threshold in x, y, and z. Tool monitoring conditions in three axes are useful to show the deep drilling process failure criterion, such as good, small corner wear, large corner wear, blunt, and fracture. Tri-axial sensors are useful in developing an online condition monitoring tool for deep drilling process, especially in tool and die industries.

Traction and braking force on three surfaces of agricultural tire lug

The objective of this research was to improve the performance of an agricultural tire by designing the shape of the tire lug. For the first stage of this research, pressure sensors were mounted in the leading lug side and the trailing lug side and tri-axial force transducers were mounted in the lug face of a small agricultural drive tire to find out the function of each lug surface. Traction forces were measured on the lug face and the leading side at 20.0% slippage and on the lug face at 10% slippage, as would be typical when a tractor is used for plowing. Braking forces were measured on the lug face and the trailing side at −10.0% slippage, as would be typical when a tractor is used for rotary tilling. The results of three tire inflation pressure conditions (39.2 kPa, 78.5 kPa and 118 kPa) also show the similar tendency to produce traction and braking forces on three surfaces of an agriculture tire lug. Relationships between forces on the lug surfaces and the soil reaction were determined.

Static load bearing exercises of individuals with transfemoral amputation fitted with an osseointegrated implant: Loading compliance.

Load-bearing exercises are performed by transfemoral amputees fitted with an osseointegrated implant to facilitate bone remodelling. This study presents the loading compliance comparing loads prescribed and applied on the three axes of the implant during static load-bearing exercises with a specific emphasis on axial and vectorial comparisons. Cohort study. A total of 11 fully rehabilitated unilateral transfemoral amputees fitted with an osseointegrated implant performed five trials in four loading conditions using a static standing frame. The load prescribed was monitored using a vertical single-axis strain gauge connected to an electronic display. The tri-axial forces applied on the implant were measured directly with an instrumented pylon including a six-channel transducer. The analysis included 'axial' and 'vectorial' comparisons corresponding to the difference between the force applied on the long axis of the implant and the load prescribed as well as the resultant of the three components of the load applied and the load prescribed, respectively. The results demonstrated that axial and vectorial differences were significant in all conditions ( p < 0.05), except for the vectorial difference for the 40 kg condition ( p = 0.182). The significant lack of axial compliance led to systematic underloading of the long axis of the implant. Clinical relevance This study contributes to a better understanding of the load applied on an osseointegrated implant during the static load-bearing exercises that could contribute to improve the design of apparatus to monitor loading exercises as well as clinical guidelines for the loading progression during rehabilitation.

Heterogeneous Sensor Data Fusion Approach for Real-time Monitoring in Ultraprecision Machining (UPM) Process Using Non-Parametric Bayesian Clustering and Evidence Theory

The aim of this paper is to detect the incipient anomalies in a ultraprecision machining (UPM) process by integrating multiple in situ sensor signals. To realize this aim we forward a Bayesian non-parametric Dirichlet Process (DP) decision-making approach for real-time monitoring of UPM process using the data gathered from multiple, heterogeneous sensors. The sensor signals are acquired under different experimental conditions from a UPM setup instrumented with a heterogeneous sensing array consisting of miniature tri-axis force, tri-axis vibration, and acoustic emission (AE) sensors mounted in close proximity to the cutting tool. We track the prominent nonlinear and non-Gaussian signal patterns evident in the experimentally acquired sensor data using an adaptive non-parametric DP modeling technique. A cohesive decision concerning the UPM process condition is made by developing a new supervised learning method, which integrates the DP-model state estimates with an evidence theoretic sensor data fusion method. Using this combined DP-evidence theoretic approach, UPM process drifts and anomalies, such as sudden changes in the depth of cut, feed rate, and spindle speed that deleteriously affect surface finish, and hence cause high yield losses, are detected and classified with over 90% accuracy (with ${ standard deviation). We compared these results with popular classification techniques, e.g., naive Bayes, self-organizing map, and support vector machine; these conventional techniques had classification accuracy in the range of 83%–88%. Consequently, this research makes the following practically relevant contributions: 1) real-time identification of the incipient UPM process anomalies from multiple sensors and 2) prescribing the optimal subset of sensors signals contingent to particular process anomalies.

Load Measurement on Foundations of Rockfall Protection Systems.

Rockfall protection barriers are connected to the ground using steel cables fixed with anchors and foundations for the steel posts. It is common practice to measure the forces in the cables, while to date measurements of forces in the foundations have been inadequately resolved. An overview is presented of existing methods to measure the loads on the post foundations of rockfall protection barriers. Addressing some of the inadequacies of existing approaches, a novel sensor unit is presented that is able to capture the forces acting on post foundations in all six degrees of freedom. The sensor unit consists of four triaxial force sensors placed between two steel plates. To correctly convert the measurements into the directional forces acting on the foundation a special in-situ calibration procedure is proposed that delivers a corresponding conversion matrix.

A Low-cost Soft Tactile Sensing Array Using 3D Hall Sensors

Tactile sensors are essential for robotic systems to safely interact with the external world and to precisely manipulate objects. Existing tactile sensors are typically either expensive or limited by poor performance, and most are not mechanically compliant. This work presents MagTrix, a soft tactile sensor array based on four 3D Hall sensors with corresponding permanent magnets. MagTrix has the capability to precisely measure triaxis force (1 mN resolution) and to determine contact area. In summary, the presented tactile sensor is robust, low-cost, high-performance and easily customizable to be integrated into a range of robotic and healthcare applications.

垂直跳びの離地時にはたらく力の計測

In this paper, the relation of plantar loading during the pre-flight phase of a vertical jump and the jump height was studied using a shoe that has MEMS triaxial force sensors on its insole of the right shoe at four points, which were hallux, first metatarsal head, fifth metatarsal head, and heel. It was found that the hallux exerts the largest force among the four anatomical regions of the foot, making it the largest contributor to the downward propulsive force. It was also found that the impulse due to heel increases with increased jump height. Likewise, in higher jumps, the impulse due to metatarsal heads are lower in comparison to that due to hallux and heel, implying that the plantar load shift from heel to hallux during ascent phase occurs more quickly while jumping to a greater height.

3軸力センサを配置した眼鏡装着型血圧脈波計測デバイス

In this study, we report on a glasses-mounted blood pressure pulse wave measurement device based on the arterial tonometry method. The glasses-mounted device consists of a fixing part to the glasses frame, an adjusting pressing force part, and an arranging sensor part to put triaxial force sensors for measuring pulse wave and body motion. We measured blood pressure pulse waves during speaking and calculated the standard deviation of the maximum and amplitude of the pulse wave. The standard deviation of the maximum decreased from 8.89 mmHg to 4.72 mmHg and that of the amplitude decreased from 6.38 mmHg to 4.25 mmHg. Since our device could reduce the influence of the body motion, standard deviation of the maximum and amplitude were decreased.