Finger Angle Research Articles

1A1-I10 装着型デバイスによる手首凹凸形状計測に基づく指関節角度推定(感覚・運動・計測)

We developed a system that estimates finger angle with a wearable device like a wrist watch. The device measures wrist contour shape changing with finger motion. Wrist contour sensing is realized by tiny photo-reflectors on the band of the device. The photo-reflectors measure distance between the band and the wrist surface. For switching the photo-reflectors, shift-register circuit is also implemented. Finger angle estimation consists of 4 steps; 1) aggregating wrist contour data of various finger motion in advance, 2) measuring wrist contour by the device, 3) selecting some similar wrist contour from the pre-measured data, 4) averaging finger angle of selected data. Moreover, contour data is corrected using particular finger motion for reduction of bad effect caused by difference of device attachment. In experiment, this system successfully estimated finger angle of finger flexion with wrist pronation.

Fingering patterns on an expanding miscible drop in a rotating Hele‐Shaw cell

AbstractWe perform a detailed numerical study for the evolution of an expanding miscible drop in a rotating Hele‐Shaw cell. Two mathematical formulations applied to model the coating layer expansion during practical spin‐coating process, such as thinning of the layer by cell pressing and drop spreading outward due to injection, are investigated. Including miscible interfacial stresses, we focus on the investigation of dynamical and morphological influences of two different stabilizing parameters: the gap width parameter for the pressing cell and the injecting strength. In the case of a pressing cell, the fingering features of the expanding miscible drop, such as the critical radius, are distinct from those ones in the experiments of spin coating due to the different distributions of the inherent radial velocity. On the other hand, the global interfacial evolutions of an expanding drop with an additional injection bear remarkable resemblances to their immiscible counterparts. The better agreement for an injecting model suggests its appropriateness when we simulate the emerging fingering instabilities in the spin‐coating process. Moreover, we investigate the effects of Coriolis force at higher miscible Bond numbers. Coriolis force affects significantly the onset of fingering instability and the tilting angles of fingers. These stable effects are in line with the results from the previous studies for miscible and immiscible flow fields. Copyright © 2007 John Wiley & Sons, Ltd.

Use of an Electromagnetic Eye Movement Monitor for Easy Measurement of Arm Movements

This paper proposes a new technique for measuring arm movements, which is an adaptation of the electromagnetic method for measuring eye movements. Two small coils of wire are mounted onto the subject's elbow, moving rigidly with the humerus, and two more coils are mounted onto the subject's wrist, moving rigidly with the radius-ulna. The subject is placed inside three alternating magnetic fields at different frequencies in the X, Y, and Z directions. As the arm moves, the voltages induced into the coils vary with angle. For each coil, the voltages are de-modulated to give three dc voltages giving the vector direction of that coil's axis. Corrections for the nonuniformity of the magnetic fields are computed. The method works unambiguously for all possible arm movements within the physiological ranges of the joints. Measurement of finger angles is just as easily done. The five angles describing arm movements can be measured at millisecond intervals with noise as small as 2 arcsec rms and drift of about 1 arcmin over a day, i.e., the electronics is more stable than the attachment of the coils to the arm.

A HIGH-PRECISION, LOW COST SYSTEM FOR EVALUATING FINGER-TAPPING TASKS

Finger-tapping test is extensively employed to assess motor asymmetry in brain damaged patients and also to study the relationship between handedness and performance in normal subjects. The aim of this study was to develop a computer based finger-tapping system that could provide quantitative measures of finger-tapping performance. The system is designed to be used in a standard personel computer without the need of any other hardware. The software is written in Borland Delphi® 6.0 for Microsoft® Windows 98® and higher operating systems. Beginning with the Pentium® processor, it could be possible to access a time-stamp counter. The time-stamp counter is a 64-bit machine specific register that is incremented by every clock cycle, and keeps an accurate count of every cycle that occurs on the processor. By using a computer with 1 GHz processor speed it is possible to reach a high precision time resolution of 1 μs in finger-tapping tests. Our future prospects for the system are to improve it with various tools such as synchronized recording of electromyography, tapping force monitoring, monitoring of finger angle, and the response to different stimulus parameters by adding appropriate hardware and procedure.

物体情報および外界センサを用いない重力下の安定ピンチング法の検証

This paper shows that secure pinching under the gravity effect can be realized by a pair of robot fingers with hemispherical ends using a coordinated sensory-feedback signal constructed without any information of an object (e.g., center of mass, mass, length, object angle) . The proposed control signals which can be easily calculated from only encoder data of the finger angles and the finger physical parameters are adaptable to rigid objects with parallel or non-parallel flat surfaces. Numerical simulations and experimental results show that the closed-loop finger-object system finally falls into some stable state satisfying the force/torque balance, that is, into a force/torque equilibrium point. In other words, the results show that stable “blind grasping” under the situation of closing eyes and neither using any tactile sensor nor force-sensing can be actualized even by a pair of robot fingers like human pinching an object by means of the thumb and index finger, provided that preshaping of finger postures is fulfilled adequately.

Numerical simulations of interfacial instabilities on a rotating miscible droplet in a time‐dependent gap Hele–Shaw cell with significant Coriolis effects

AbstractInterfacial instability of a rotating miscible droplet with significant Coriolis force in a Hele–Shaw cell is simulated numerically. The influences of the relevant control parameters are first discussed qualitatively by fingering patterns. More vigorous fingerings are found at higher rotational effects, a lower viscosity contrast and a weaker effective surface tension (Korteweg constant). For a time‐dependent gap Hele–Shaw cell, a higher cell lifting rate makes the rotating droplet bear an inward straining flow, which leads to fingering enhancement. On the contrary, a higher pressing rate provides more stable effects by additional squeezing outward flow. A quantitative analysis between the Coriolis effects and tilting angles of fingers is addressed. For arbitrary combinations of all relevant control parameters, the values of tilting angles follow a nearly linear relationship with the Coriolis effects. We estimate the correlation between the relevant control parameters (dimensionless Coriolis factor Re, viscosity parameter R, cell lifting rate a) and tilting angles (θ) of fingers that can be approximated as $\theta = (0.0047\sqrt {Pe/R} + 18.2a)Re$ for significant Korteweg stresses. Copyright © 2005 John Wiley & Sons, Ltd.

Compliant grasp in a myoelectric hand prosthesis

A novel myoelectric hand prosthesis consisting of electromyogram (EMG) signal processing units, a microprocessor-based dc motor servo system, and a 1 degree-of-freedom (DOF) end effector has been developed. The flexion angle and compliance of the finger of this prosthesis can be voluntarily controlled with EMG signals. The biomimetic controller for the myoelectric hand incorporated a model of the neuromuscular control system constructed from an analysis of the force response to length perturbation of the flexor pollicis longus muscle, processing of EMG signals, and the configuration of the hand. Basic functions of the human neuromuscular control system are realized by using position control, force feedback, and variable gain, modulated by EMG signal amplitude. A limb-absent person and four healthy subjects were able to voluntarily control the finger angle and compliance of the prosthesis and were able to easily grasp a soft object after a short training period.

Hand Shape Switch for Instrument Panel Using the Single Eye Camera

In this paper, we propose a system for switching operation of vehicle instrument panel by hand gesture. When driving a vehicle, a driver often needs to watch instrument panels for switching operation, such as an air-conditioner and an audio system, although such operation might reduce visual attention of vehicle-front view for safety driving. The proposed system makes a driver to perform such switching operation by hand gesture without watching the instrument panel. This system captures images of a driver’s hand with the camera attached on the ceiling inside of a vehicle. The angle of the index finger are detected by processing the captured image sequence. The detected hand’s motion is recognized as switching operations instead of the switching operation on the instrument panel. This system has two modes for controlling audio and air-conditioner. The first mode is for selecting the control function, such as volume of audio, temperature of air-conditioner, and strength of the airflow. Such selection is performed by pushing gesture by the index finger. Next, the value of the selected function is adjusted by the position of the hand. Using this system, the driver can control the interior systems without watching the instrument panel, so that the visual burden at the time of the switch operation can be reduced.

Effect of age on functional anthropometry of older Mexican American adults: a cross-sectional study

Overall goal of the research reported in this paper was to determine if, and to what extent, age affects functional anthropometry of older Mexican American adults. Primary objectives were: (1) to determine if age affects limiting functional outer fingertip and grip reaches, for women and men separately; and (2) to determine, through a cross-sectional comparison, if functional anthropometric measures of older Mexican American females and males are different from a younger group of Mexican American females and males. Determining through factor analysis, a smaller number of explanatory factors from 15 different observed functional anthropometric measures observed was a secondary objective. Older Mexican American women and men, aged 60–85, recruited from Senior Centers in El Paso, and young Mexican American adults, aged 20–29, recruited for the study from the student body at the University of Texas at El Paso, were participants in the study. Stature, several vertical fingertip and grip reaches, and several horizontal fingertip and grip reaches, among other dimensions, were measured. Linear regression models were fit for older women and men separately, with age as the independent variable and functional anthropometric dimensions as dependent variables. Two-sample t-tests were conducted to analyze cross-sectional differences between the older and young Mexican American females, and older and young Mexican American males. Regression analysis results show a significant linear relationship between age and sitting height for females ( p<0.05), and stature ( p<0.05) and sitting height ( p<0.05) for males. Cross-sectional two-sample t-tests show statistically that older Mexican American female stature, vertical fingertip reach, vertical reach angle, sitting height, horizontal fingertip reaches at 0° and 90°, horizontal lateral fingertip reach, horizontal reach angle, horizontal grip reaches (lateral, and at 0° and 90°), mean grip diameter, and finger angle, are significantly different from Mexican American young females. Stature, vertical fingertip and grip reaches, vertical reach angle, sitting height and horizontal reach angle are significantly different between older and young Mexican American males. None of the horizontal reaches were significantly different for males. Overall, functional reach differences in Mexican American women were found to be more pronounced than functional reach differences in Mexican American men. Relevance to industry Functional anthropometry affects functional performance of older persons, both in work settings, and in activities of daily living. Engineering designers, particularly, product designers and engineers in the housing industry, need to consider functional anthropometry of older persons when designing daily living environments and products of daily use for older users.

The effect of eccentric exercise on intrinsic and reflex stiffness in the human hand

Objective. The purpose of this work was to determine the effect of strenuous eccentric exercise on joint stiffness and to separate joint stiffness into components due to intrinsic muscle mechanics and delayed reflex muscle activation. Design. Subjects performed 100 maximal eccentric contractions, using the first dorsal interosseus muscle to abduct the index finger while undergoing a 20° displacement of the metacarpophalangeal joint. Joint stiffness was measured 24 h later during 15% and 65% maximal voluntary contraction and during electrical muscle stimulation at 15% of maximal voluntary contraction torque. Background. Joint stiffness can be varied by changing voluntary muscle activation and thereby serves an important role in joint stabilization. Eccentric exercise has been shown to result in muscle fiber injury, reducing maximal muscle force. However, it is not known whether intrinsic muscle stiffness or reflex stiffness is also affected. Methods. Displacements of 3° amplitude were used to estimate joint stiffness about the neutral angle of the index finger. The difference between measurements made during voluntary muscle activation and electrical muscle stimulation was used to obtain reflex stiffness. Results. There was no change in the passive joint stiffness nor was there any change in either the intrinsic or reflex stiffness at 15% maximal voluntary contraction. However, intrinsic stiffness for the electrically stimulated muscle was higher post-exercise than pre-exercise, while active joint stiffness at 65% maximal voluntary contraction (comprising intrinsic and reflex stiffness) was lower. Conclusion. The observed mechanical changes are compatible with the hypothesis that type II muscle fibers are more susceptible to injury than type I muscle fibers, which have higher intrinsic stiffness. Relevance Muscle stiffness is important for maintaining mechanical stability of a joint. The effects of eccentric exercise on muscle stiffness are likely analogous to the effects of muscle injury, making this a good model for biomechanical changes associated with muscle injury.

Linked proximal and distal changes in the reaching behavior of 5- to 12-month-old human infants grasping objects of different sizes

This study evaluates age-related proximal and distal changes in reaching organization for objects of different sizes. To this end, eight objects ranging from 2 to 9 cm diam. were presented to 23 infants ages 5 to 12 months. Proximal control was determined by the relative frequencies of bimanual reaching for large and small objects. Distal control was assessed by hand opening and orientation with respect to an object, and by the proportion of the object being included within hand opening at touch. Five-month-old infants tended to reach bimanually regardless of object size. Starting at 7 to 8 months, infants tended to reach for large objects bimanually more often than for small ones. Only at 11 to 12 months did reaching closely reflect the object’s diameter. The frequency of thumb-index finger angle opening during the approach phase also increased after 7 to 8 months of age, as well as the adjustment of the angle to the object diameter and the proportion of the object within hand opening at touch. Proximal and distal changes appeared coupled at 5 to 6 months, when the few subjects showing evidence of some proximal adjustments to object size were also those who exhibited some distal adjustments. After they started to appear, however, proximal and distal adjustments seemed to be independent, as revealed by the lack of correlation of proximal and distal changes between 7 and 12 months.

オンオフ型およびバイオミメティック型筋電義手の3D-CGシミュレータの開発

Some kinds of myoelectric prosthetic hand, which use myoelectric signals (EMGs) of muscles as control signals for opening and closing, are used to replace the functions of a natural hand lost by amputation. Chances for an amputee to watch, touch, and use a myoelectric hand are very rare in Japan, because few hospitals give information on them and are provided with actual myoelectric hands. A simulator of a myoelectric hand can enable an amputee to use myoelectric hands virtually. The purpose of this study is to develop a 3 D-CG (three-dimensional computer graphics) simulator of an on-off control myoelectric hand and a biomimetic myoelectric hand. The former is produced by Otto Bock, and the latter was developed by our group. Both prosthetic hands are one-degree-of-freedom units with simultaneous opening and closing of thumb, index, and middle fingers. In the on-off control hand, either opening or closing is determined by the EMG amplitudes of flexor and extensor muscles. In the biomimetic hand, both the finger angle and the compliance are controlled by the EMGs. First, in this simulator, the EMGs are detected with special surface electrodes used for each hand. Second, the finger angle of the prosthetic hand is calculated from the EMGs with the model. Third, positions of the subject's upper limb are measured. Finally, the hand and the upper limb are displayed with 3 D-CG. It was found, in the on-off control hand, that the rate of change of finger angle was dependent on the finger angle. We constructed a model of the on-off control hand; the rate of angle change was determined from the output of the EMG electrode and the present finger angle. Using this model, the finger angle was calculated from the EMG electrode output and the initial finger angle. In the model of the biomimetic hand, an ideal relation between EMG input and finger angle output was utilized, although the real biomimetic myoelectric hand had complex nonlinear properties, such as friction and saturation. Using the model, the finger angle was calculated from the EMG output of the surface electrode. The positions of shoulder, elbow, and wrist were observed with a three-dimensional position sensor, and the posture of the upper limb was calculated. In this simulator, the posture of the upper limb was drawn with a stick picture and the orientation of the prosthetic hand was displayed with 3 D-CG. The experiment was conducted on normal subjects. Watching the 3D-CG of the simulator, they could easily control the finger angle and orientation of the hand.

A Study on Tele-Existence of the Tactile Sense

This report describes, first, a glove with joint angle sensors made of chip coils to detect the joint angles of human fingers in real time and also describes artificial fingers with multiple joints used for a tele-existence system on the tactile sense. Characteristics of the artificial skin to be attached to the artificial fingers are based on the experimental results of force-displacement characteristics of the human skin. Secondly, sensations produced by the pressure and the strain applied to the finger tip surface were measured as functions of pressure force level and the direction of the strain force using psychophysical techniques. A study of pressure sense and a force vector sensor is useful from the view point of the tele-existence system for the tactile sense.

Mechanics of the onager

A mathematical model is proposed, apparently for the first time, for the onager, a late Roman catapult. The elastic energy of the machine is contained in a cylindrical bundle of twisted elastic cords, and, although each cord satisfies a linear stress-strain law, the geometry of the entire bundle causes a torque to be exerted on the moving arm of the onager which is a nonlinear function of the angular deflection of the arm. This torque is used in the nonlinear differential equations of motion which are integrated numerically. Experimental work is described which assists in determining the torque, and in addition supplies ranges for the projectiles for various masses, sling lengths and finger angles (parts of the release mechanism). Predictions from the mathematics are in reasonable agreement with experiment. A new calibration rule for the onager is proposed, based on the numerical integrations, which complements that known since classical times for the two-armed Greek palintone. Finally an appendix contains a discussion of the effect of a buffer on the motion.

Insulation workers in Belfast. 1. Comparison of a random sample with a control population

<b>Wallace, W. F. M., and Langlands, J. H. M. (1971).</b><i>Brit. J. industr. Med.,</i><b>28,</b> 211-216. <b>Insulation workers in Belfast. 1. Comparison of a random sample with a control population.</b> A sample of 50 men was chosen at random from the population of asbestos insulators in Belfast and matched with a control series of men of similar occupational group with respect to age, height, and smoking habit. Significantly more of the insulators complained of cough and sputum and had basal rales on examination. Clubbing was assessed by means of measurements of the hyponychial angle of both index fingers. These angles were significantly greater in the group of insulators. Twenty-one insulators had ϰ-rays which showed pleural calcification with or without pulmonary fibrosis; one control ϰ-ray showed pulmonary fibrosis. The insulators had no evidence of airways obstruction but static lung volume was reduced and their arterial oxygen tension was lower than that of the controls and their alveolar-arterial oxygen gradient was greater.