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Characterization of surface electromyography using time domain features for determining hand motion and stages of contraction

Bin Ahmad Nadzri AA, Ahmad SA, Marhaban MH, Jaafar H

Australas Phys Eng Sci Med, 2014 Mar;37(1):133-7.
PMID: 24443218 DOI: 10.1007/s13246-014-0243-3

Surface electromyography (SEMG) signals can provide important information for prosthetic hand control application. In this study, time domain (TD) features were used in extracting information from the SEMG signal in determining hand motions and stages of contraction (start, middle and end). Data were collected from ten healthy subjects. Two muscles, which are flexor carpi ulnaris (FCU) and extensor carpi radialis (ECR) were assessed during three hand motions of wrist flexion (WF), wrist extension (WE) and co-contraction (CC). The SEMG signals were first segmented into 132.5 ms windows, full wave rectified and filtered with a 6 Hz low pass Butterworth filter. Five TD features of mean absolute value, variance, root mean square, integrated absolute value and waveform length were used for feature extraction and subsequently patterns were determined. It is concluded that the TD features that were used are able to differentiate hand motions. However, for the stages of contraction determination, although there were patterns observed, it is determined that the stages could not be properly be differentiated due to the variability of signal strengths between subjects.

Matched MeSH terms: Hand/physiology*
Fulltext Flex Sensor Compensator via Hammerstein-Wiener Modeling Approach for Improved Dynamic Goniometry and Constrained Control of a Bionic Hand

Syed Mubarak Ali SAA, Ahmad NS, Goh P

Sensors (Basel), 2019 Sep 10;19(18).
PMID: 31509987 DOI: 10.3390/s19183896

In this paper, a new control-centric approach is introduced to model the characteristics of flex sensors on a goniometric glove, which is designed to capture the user hand gesture that can be used to wirelessly control a bionic hand. The main technique employs the inverse dynamic model strategy along with a black-box identification for the compensator design, which is aimed to provide an approximate linear mapping between the raw sensor output and the dynamic finger goniometry. To smoothly recover the goniometry on the bionic hand's side during the wireless transmission, the compensator is restructured into a Hammerstein-Wiener model, which consists of a linear dynamic system and two static nonlinearities. A series of real-time experiments involving several hand gestures have been conducted to analyze the performance of the proposed method. The associated temporal and spatial gesture data from both the glove and the bionic hand are recorded, and the performance is evaluated in terms of the integral of absolute error between the glove's and the bionic hand's dynamic goniometry. The proposed method is also compared with the raw sensor data, which has been preliminarily calibrated with the finger goniometry, and the Wiener model, which is based on the initial inverse dynamic design strategy. Experimental results with several trials for each gesture show that a great improvement is obtained via the Hammerstein-Wiener compensator approach where the resulting average errors are significantly smaller than the other two methods. This concludes that the proposed strategy can remarkably improve the dynamic goniometry of the glove, and thus provides a smooth human-robot collaboration with the bionic hand.

Matched MeSH terms: Hand/physiology*
Standardized translated instruction versus spontaneously translated instruction: Test-retest and interrater reliability of a hand function test

Lim YX, Chai SC

J Hand Ther, 2020 03 04;33(4):553-561.
PMID: 32143983 DOI: 10.1016/j.jht.2019.09.001

STUDY DESIGN: Cross-sectional study.
INTRODUCTION: Adhering to test administration and standardized instructions is important for attainment of accurate and reliable results in performance-based tests.
PURPOSE OF THE STUDY: To determine test-retest and interrater reliability of standardized translated instruction (St-TI) and spontaneously translated instruction (Sp-TI) of a hand function test.
METHODS: Four raters and seventy-two subjects were divided into 2 groups: St-TI group, direct administration of the Hong Kong Chinese version of the Jebsen Hand Function Test to subjects by raters; and Sp-TI group, spontaneously translating the Jebsen-Taylor Hand Function Test from English into Chinese by raters. Test-retest and interrater reliability were calculated based on instruction time by the rater and performance time by the subject.
RESULTS: Test-retest and interrater reliability of instruction time by rater for St-TI has intraclass correlation coefficient of 0.35 to 0.70 and 0.24 to 0.55, respectively, whereas that for Sp-TI was -0.50 to 0.18 and -0.09 to 0.51, respectively. Test-retest and interrater reliability of performance time by subject for St-TI was 0.56 to 0.84 and 0.33 to 0.78, respectively, whereas that for Sp-TI was 0.54 to 0.87 and 0.35 to 0.77, respectively. Sp-TI had two test-retest minimal detectable change percent values that fell within the acceptable range (subtest 3 = 21.9% and subtest 6 = 25.7%).
CONCLUSION: Instruction time by rater for Jebsen-Taylor Hand Function Test subtests had generally poor to moderate test-retest and interrater reliability for both St-TI and Sp-TI. Performance time by subject generally had moderate to good reliability, except for St-TI with poor to good interrater reliability.

Matched MeSH terms: Hand/physiology*
Fulltext A novel and improved method of predicting hand grip strength in the adult Malaysian population

Kamarul T, Ahmad TS, Loh WY

Med J Malaysia, 2006 Dec;61 Suppl B:37-44.
PMID: 17600991

Hand grip strength measurement is a recognized part of hand function assessment. The standard measurement using the Jamar dynamometer and comparing these results to the recommended normal values suggested by the manufacturers of the Jamar was questioned as these values were based on Western population. A study comparing a novel method of predicting grip strength using our software was conducted on 25 normal subjects using the LIDO kinetic workset (Group A and B ). These results were then compared against our predictive software (Group A) and the expected values supplied together with the Jamar Dynamometer (Group B). In another group, 22 normal subjects were tested using the Jamar (Group C and D) and then matched against the predicted values using their recommended chart (Group C). The last group (Group D) was tested using the Jamar but the values attained were compared to the results from our software. In group A, the predictability of our predictive method was 100% (both R & L) as compared to (R = 64%, L = 68%) in group B, (R = 27.3%, L = 59.1%) in group C and (R = 81.8%, L = 86.4%) in group D. The differences between the predictability of both methods were statistically significant. The data collected using both the Jamar and the LIDO kinetic workset correlated well to the data from our software but not to the values suggested by the manufacturers of Jamar. We conclude that our method of predicting hand grip values are superior to that suggested by the manufacturers of dynamometers. The standard reference for hand grip strength provided by the manufacturers is less accurate in predicting the grip strength of our local population.

Matched MeSH terms: Hand/physiology*
Fulltext Objective triceps muscle strength measurement using computerized adaptation

Amalourde A, Vinayaga P, Naveed N, Choon SK, Zaleha O

Med J Malaysia, 2004 Dec;59 Suppl F:8-13.
PMID: 15941154

In our centre the non-availability computerized exercise machines limits the objective monitoring of strength rehabilitation. We undertook this research programme to objectively measure triceps muscle strength by interfacing NORSK-Gym machine with accelerometer and positional transducers to a computer. This data was tabulated and processed using Microsoft Excel. The positional transducer was first calibrated and it showed an excellent Pearson Correlation Coefficients against a standard metric reading (r = 0.9999). Peak Force was used as a test parameter for isotonic triceps muscle strength measurements. The criterion-referenced validity was established as the peak forces measured using the accelerometer and positional transducer demonstrated identical Peak Forces (r = 0.94). Analysis of our mean Peak Force measurements using non-biological force as well as the intra-individual reproducibility demonstrated excellent Pearson Correlation Coefficients (r) = 0.982-0.998 and 0.929-0.972 respectively. This computerized adaptation of the NORSK-Gym machine produced an objective, valid and reproducible triceps muscle strength measurement.

Matched MeSH terms: Hand/physiology*
Normal values for total hand length, palm length and middle finger length in Malaysian newborns from 34-42 weeks of gestation

Halder D, Dharap AS, Than M

Anthropol Anz, 1999 Mar;57(1):69-75.
PMID: 10320927

Early identification of a syndrome at birth is of paramount importance for genetic counselling and possible prevention. Often malformation of the hands and fingers are cardinal manifestations of recognizable syndromes. As there are no published standards for hand and finger size for Malay newborn infants, this study was undertaken to establish normal values for hand, middle finger and palmar lengths, and their indices. A cross-sectional study was done on 509 consecutive newborn Malay babies between 34 and 42 weeks of gestation. Measurements were made on the right hand according to the recommended guidelines of Bergsma & Feingold (1975). The mean values for the measurements did not differ significantly between boys and girls, or change with gestation. For the whole group the mean value for total hand length was 64.4 +/- 3.42 mm, middle finger length 37.1 +/- 2.91 mm, palmar length 27.4 +/- 2.15 mm, finger index 0.425 +/- 0.03 and palmar index 0.58 +/- 0.03. A comparison with published measurements for newborns of different racial origin shows significant differences for the total hand length, middle finger length and palm length from Indian and Jewish infants, but not from Japanese infants. The indices were similar in Malay, Indian, Jewish and Japanese newborn infants.

Matched MeSH terms: Hand/physiology*
Transmission of vibration through glove materials: effects of contact force

Md Rezali KA, Griffin MJ

Ergonomics, 2018 Sep;61(9):1246-1258.
PMID: 29628001 DOI: 10.1080/00140139.2018.1462407

This study investigated effects of applied force on the apparent mass of the hand, the dynamic stiffness of glove materials and the transmission of vibration through gloves to the hand. For 10 subjects, 3 glove materials and 3 contact forces, apparent masses and glove transmissibilities were measured at the palm and at a finger at frequencies in the range 5-300 Hz. The dynamic stiffnesses of the materials were also measured. With increasing force, the dynamic stiffnesses of the materials increased, the apparent mass at the palm increased at frequencies greater than the resonance and the apparent mass at the finger increased at low frequencies. The effects of force on transmissibilities therefore differed between materials and depended on vibration frequency, but changes in apparent mass and dynamic stiffness had predictable effects on material transmissibility. Depending on the glove material, the transmission of vibration through a glove can be increased or decreased when increasing the applied force. Practitioner summary: Increasing the contact force (i.e. push force or grip force) can increase or decrease the transmission of vibration through a glove. The vibration transmissibilities of gloves should be assessed with a range of contact forces to understand their likely influence on the exposure of the hand and fingers to vibration.

Matched MeSH terms: Hand/physiology*
Fulltext Rubber hands in space: the role of distance and relative position in the rubber hand illusion

Kalckert A, Perera AT, Ganesan Y, Tan E

Exp Brain Res, 2019 Jul;237(7):1821-1832.
PMID: 31079236 DOI: 10.1007/s00221-019-05539-6

The rubber hand illusion (RHI) is a perceptual phenomenon in which participants experience ownership over a fake model hand through synchronous visuotactile stimulation. Several studies have shown that the illusion occurs only when both hands are in close proximity to each other. In the present study, we systematically examined the role of relative position (lateral, distal) and distance (13-75 cm) of the model hand (with respect to participants' real hand) on illusion experience across both lateral and distal positions. Furthermore, we also compared different facets of the subjective illusion experience; the experience of the model hand being part of one's body (i.e., ownership) and the perceptual fusion of vision and touch (i.e., referral of touch). In two experiments we observed indications for a stronger illusion experiences in distal compared to lateral positions of identical distances, indicating that the illusory effects may vary as a function of the relative position of the hand. Our results also showed that manipulations of distance differently modulated both facets of the illusion. While ownership was restricted to near distances, referral of touch sensations remained stable at farther distances. These results are interpreted in relation to variations in sensory weighting across different planes.

Matched MeSH terms: Hand/physiology*
Fulltext Normative data for hand grip strength and key pinch strength, stratified by age and gender for a multiethnic Asian population

Lam NW, Goh HT, Kamaruzzaman SB, Chin AV, Poi PJ, Tan MP

Singapore Med J, 2016 Oct;57(10):578-584.
PMID: 26768064 DOI: 10.11622/smedj.2015164

INTRODUCTION: Hand strength is a good indicator of physical fitness and frailty among the elderly. However, there are no published hand strength references for Malaysians aged > 65 years. This study aimed to establish normative data for hand grip strength (HGS) and key pinch strength (KPS) for Malaysians aged ≥ 60 years, and explore the relationship between hand strength and physical ability.
METHODS: Healthy participants aged ≥ 60 years with no neurological conditions were recruited from rural and urban locations in Malaysia. HGS and KPS were measured using hand grip and key pinch dynamometers. Basic demographic data, anthropometric measures, modified Barthel Index scores and results of the Functional Reach Test (FRT), Timed Up and Go (TUG) test and Jebsen-Taylor Hand Function Test (JTHFT) were recorded.
RESULTS: 362 subjects aged 60-93 years were recruited. The men were significantly stronger than the women in both HGS and KPS (p < 0.001). The hand strength of the study cohort was lower than that of elderly Western populations. Significant correlations were observed between hand strength, and residential area (p < 0.001), FRT (r = 0.236, p = 0.028), TUG (r = -0.227, p = 0.009) and JTHFT (r = -0.927, p < 0.001).
CONCLUSION: This study established reference ranges for the HGS and KPS of rural and urban elderly Malaysian subpopulations. These will aid the use of hand strength as a screening tool for frailty among elderly persons in Malaysia. Future studies are required to determine the modifiable factors for poor hand strength.

Matched MeSH terms: Hand/physiology*
Fulltext Higher-order Brain Areas Associated with Real-time Functional MRI Neurofeedback Training of the Somato-motor Cortex

Auer T, Dewiputri WI, Frahm J, Schweizer R

Neuroscience, 2018 May 15;378:22-33.
PMID: 27133575 DOI: 10.1016/j.neuroscience.2016.04.034

Neurofeedback (NFB) allows subjects to learn self-regulation of neuronal brain activation based on information about the ongoing activation. The implementation of real-time functional magnetic resonance imaging (rt-fMRI) for NFB training now facilitates the investigation into underlying processes. Our study involved 16 control and 16 training right-handed subjects, the latter performing an extensive rt-fMRI NFB training using motor imagery. A previous analysis focused on the targeted primary somato-motor cortex (SMC). The present study extends the analysis to the supplementary motor area (SMA), the next higher brain area within the hierarchy of the motor system. We also examined transfer-related functional connectivity using a whole-volume psycho-physiological interaction (PPI) analysis to reveal brain areas associated with learning. The ROI analysis of the pre- and post-training fMRI data for motor imagery without NFB (transfer) resulted in a significant training-specific increase in the SMA. It could also be shown that the contralateral SMA exhibited a larger increase than the ipsilateral SMA in the training and the transfer runs, and that the right-hand training elicited a larger increase in the transfer runs than the left-hand training. The PPI analysis revealed a training-specific increase in transfer-related functional connectivity between the left SMA and frontal areas as well as the anterior midcingulate cortex (aMCC) for right- and left-hand trainings. Moreover, the transfer success was related with training-specific increase in functional connectivity between the left SMA and the target area SMC. Our study demonstrates that NFB training increases functional connectivity with non-targeted brain areas. These are associated with the training strategy (i.e., SMA) as well as with learning the NFB skill (i.e., aMCC and frontal areas). This detailed description of both the system to be trained and the areas involved in learning can provide valuable information for further optimization of NFB trainings.

Matched MeSH terms: Hand/physiology
Investigating the performance of an amplitude-independent algorithm for detecting the hand muscle activity of stroke survivors

Hameed HK, Wan Hasan WZ, Shafie S, Ahmad SA, Jaafar H, Inche Mat LN

J Med Eng Technol, 2020 Apr;44(3):139-148.
PMID: 32396756 DOI: 10.1080/03091902.2020.1753838

To make robotic hand devices controlled by surface electromyography (sEMG) signals feasible and practical tools for assisting patients with hand impairments, the problems that prevent these devices from being widely used have to be overcome. The most significant problem is the involuntary amplitude variation of the sEMG signals due to the movement of electrodes during forearm motion. Moreover, for patients who have had a stroke or another neurological disease, the muscle activity of the impaired hand is weak and has a low signal-to-noise ratio (SNR). Thus, muscle activity detection methods intended for controlling robotic hand devices should not depend mainly on the amplitude characteristics of the sEMG signal in the detection process, and they need to be more reliable for sEMG signals that have a low SNR. Since amplitude-independent muscle activity detection methods meet these requirements, this paper investigates the performance of such a method on people who have had a stroke in terms of the detection of weak muscle activity and resistance to false alarms caused by the involuntary amplitude variation of sEMG signals; these two parameters are very important for achieving the reliable control of robotic hand devices intended for people with disabilities. A comparison between the performance of an amplitude-independent muscle activity detection algorithm and three amplitude-dependent algorithms was conducted by using sEMG signals recorded from six hemiparesis stroke survivors and from six healthy subjects. The results showed that the amplitude-independent algorithm performed better in terms of detecting weak muscle activity and resisting false alarms.

Matched MeSH terms: Hand/physiology*

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