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Rehabilitation Engineering, IEEE Transactions on

Popular Articles (January 2015)

Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
  • 1. Optimal spatial filtering of single trial EEG during imagined hand movement

    Publication Year: 2000 , Page(s): 441 - 446
    Cited by:  Papers (381)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    The development of an electroencephalograph (EEG)-based brain-computer interface (BCI) requires rapid and reliable discrimination of EEG patterns, e.g., associated with imaginary movement. One-sided hand movement imagination results in EEG changes located at contra- and ipsilateral central areas. The authors demonstrate that spatial filters for multichannel EEG effectively extract discriminatory information from two populations of single-trial EEG, recorded during left- and right-hand movement imagery. The best classification results for three subjects are 90.8%, 92.7%, and 99.7%. The spatial filters are estimated from a set of data by the method of common spatial patterns and reflect the specific activation of cortical areas. The method performs a weighting of the electrodes according to their importance for the classification task. The high recognition rates and computational simplicity make it a promising method for an EEG-based brain-computer interface View full abstract»

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  • 2. Robot-aided neurorehabilitation

    Publication Year: 1998 , Page(s): 75 - 87
    Cited by:  Papers (381)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    The authors' goal is to apply robotics and automation technology to assist, enhance, quantify, and document neurorehabilitation. This paper reviews a clinical trial involving 20 stroke patients with a prototype robot-aided rehabilitation facility developed at the Massachusetts Institute of Technology, Cambridge, (MIT) and tested at Burke Rehabilitation Hospital, White Plains, NY. It also presents the authors' approach to analyze kinematic data collected in the robot-aided assessment procedure. In particular, they present evidence (1) that robot-aided therapy does not have adverse effects, (2) that patients tolerate the procedure, and (3) that peripheral manipulation of the impaired limb may influence brain recovery. These results are based on standard clinical assessment procedures. The authors also present one approach using kinematic data in a robot-aided assessment procedure View full abstract»

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  • 3. The mental prosthesis: assessing the speed of a P300-based brain-computer interface

    Publication Year: 2000 , Page(s): 174 - 179
    Cited by:  Papers (300)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (76 KB)  

    Describes a study designed to assess a brain-computer interface (BCI), originally described by Farwell and Donchin in 1988. The system utilizes the fact that the rare events in the oddball paradigm elicit the P300 component of the event-related potential (ERP). The BCI presents the user with a matrix of 6 by 6 cells, each containing one letter of the alphabet. The user focuses attention on the cell containing the letter to be communicated while the rows and the columns of the matrix are intensified. Each intensification is an event in the oddball sequence, the row and the column containing the attended cell are “rare” items and, therefore, only these events elicit a P300. The computer thus detects the transmitted character by determining which row and which column elicited the P300. The authors report an assessment, using a bootstrapping approach, which indicates that an off line version of the system can communicate at the rate of 7.8 characters a minute and achieve 80% accuracy. The system's performance in real time was also assessed. The authors' data indicate that a P300-based BCI is feasible and practical. However, these conclusions are based on tests using healthy individuals View full abstract»

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  • 4. Evaluation of a rehabilitative pedorthic: plantar pressure alterations with scaphoid pad application

    Publication Year: 1996 , Page(s): 328 - 336
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1492 KB)  

    Scaphoid or longitudinal arch pads are frequently prescribed pedorthics for foot and ankle rehabilitation. These pedorthics are reported to be effective in mechanically supporting the medial longitudinal arch while reducing plantar and medial soft tissue strain. The objective of this study was to measure alterations in ambulatory planter pressure metrics in a group of adults secondary to scaphoid pad application. The biomechanical rationale of this study was that the geometry of foot contact would be altered secondary to foot inversion. Ten adult male subjects with biomechanically normal feet were evaluated during multiple trials. A Holter type microprocessor-based portable in-shoe plantar pressure data acquisition system was used to record the dynamic data. Pressures were recorded from eight discrete planter locations at the hindfoot, midfoot, and forefoot regions of the insole. Statistically significant (p⩽0.05) increases in peak pressures were seen laterally with scaphoid pad application, while significant decreases in peak pressures with pad usage occurred at the hallux and the calcaneal region of the foot. At the medial longitudinal arch, peak pressures increased from near 0 to 115.3 kPa, contact durations increased from near 0 to 438 ms, and pressure-time integrals increased from near 0 to 33.4 kPa·s View full abstract»

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  • 5. Real-time EEG analysis with subject-specific spatial patterns for a brain-computer interface (BCI)

    Publication Year: 2000 , Page(s): 447 - 456
    Cited by:  Papers (69)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Electroencephalogram (EEG) recordings during right and left motor imagery allow one to establish a new communication channel for, e.g., patients with amyotrophic lateral sclerosis. Such an EEG-based brain-computer interface (BCI) can be used to develop a simple binary response for the control of a device. Three subjects participated in a series of on-line sessions to test if it is possible to use common spatial patterns to analyze EEG in real time in order to give feedback to the subjects. Furthermore, the classification accuracy that can be achieved after only three days of training was investigated. The patterns are estimated from a set of multichannel EEG data by the method of common spatial patterns and reflect the specific activation of cortical areas. By construction, common spatial patterns weight each electrode according to its importance to the discrimination task and suppress noise in individual channels by using correlations between neighboring electrodes. Experiments with three subjects resulted in an error rate of 2, 6 and 14% during on-line discrimination of left- and right-hand motor imagery after three days of training and make common spatial patterns a promising method for an EEG-based brain-computer interface View full abstract»

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  • 6. Brain-computer interface technology: a review of the first international meeting

    Publication Year: 2000 , Page(s): 164 - 173
    Cited by:  Papers (342)  |  Patents (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

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  • 7. Separability of EEG signals recorded during right and left motor imagery using adaptive autoregressive parameters

    Publication Year: 1998 , Page(s): 316 - 325
    Cited by:  Papers (136)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    Electroencephalogram (EEG) recordings during right and left motor imagery can be used to move a cursor to a target on a computer screen. Such an EEG-based brain-computer interface (BCI) can provide a new communication channel to replace an impaired motor function. It can be used by, e.g., patients with amyotrophic lateral sclerosis (ALS) to develop a simple binary response in order to reply to specific questions. Four subjects participated in a series of on-line sessions with an EEG-based cursor control. The EEG was recorded from electrodes overlying sensory-motor areas during left and right motor imagery. The EEG signals were analyzed in subject-specific frequency bands and classified on-line by a neural network. The network output was used as a feedback signal. The on-line error (100%-perfect classification) was between 10.0 and 38.1%. In addition, the single-trial data were also analyzed off-line by using an adaptive autoregressive (AAR) model of order 6. With a linear discriminant analysis the estimated parameters for left and right motor imagery were separated. The error rate, obtained varied between 5.8 and 32.8% and was, on average, better than the on-line results. By using the AAR-model for on-line classification an improvement in the error rate can be expected, however, with a classification delay around 1 s View full abstract»

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  • 8. Direct control of a computer from the human central nervous system

    Publication Year: 2000 , Page(s): 198 - 202
    Cited by:  Papers (165)  |  Patents (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB)  

    Describes an invasive alternative to externally applied brain-computer interface (BCI) devices. This system requires implantation of a special electrode into the outer layers of the human neocortex. The recorded signals are transmitted to a nearby receiver and processed to drive a cursor on a computer monitor in front of the patient. The authors' present patient has learned to control the cursor for the production of synthetic speech and typing View full abstract»

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  • 9. EMG feature evaluation for movement control of upper extremity prostheses

    Publication Year: 1995 , Page(s): 324 - 333
    Cited by:  Papers (50)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    A variety of EMG features have been evaluated for control of myoelectric upper extremity prostheses. Movement class discrimination, robustness, and computational complexity of these features have been investigated for different time window sizes and noise levels. The measurements include novel application of the Davies-Bouldin index, a measure of cluster separability, and the K-nearest neighbor nonparametric classifier. The features evaluated are the integral of average value, the variance, the number of zero crossings, the Willison amplitude, the v-order and log detectors, and autoregressive model parameters. A new feature, the EMG Histogram, is introduced and shown to be the most effective of the group. The experiments were done on the data acquired from the residual biceps and triceps muscle of an above-elbow amputee View full abstract»

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  • 10. A Holter-type microprocessor-based rehabilitation instrument for acquisition and storage of plantar pressure data in children with cerebral palsy

    Publication Year: 1996 , Page(s): 33 - 38
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    A multichannel, portable data acquisition system has been developed to measure discrete plantar pressures in the rehabilitation of children who have cerebral palsy and planovalgus foot deformity. The microprocessor-based system is designed to be lightweight (350 g with batteries) and portable (no umbilicus) in order to minimize encumbrances to gait patterns. It provides an improved method for obtaining accurate and reliable data during extended recording and rehabilitative periods that is not available from commercial systems. Twelve conductive polymer force (pressure) sensors are used to acquire pressure data, which are then stored in the system memory. Plantar pressures are sampled at a rate of 40 Hz from each of the 12 sensors for up to 2 h. The system consists of 16 analog amplifiers, a 12 b sampling analog-to-digital converter, an 8 b Dallas semiconductor microprocessor (DS5001FP-16, Dallas, TX), 4 MB of pseudo static RAM, and serial and parallel I/O interfaces. The interfaces are used to upload data into a PC for further processing, analysis, and display. During subject testing, sensors are located at predetermined anatomic areas under the calcaneus, medial and lateral midfoot, medial and lateral metatarsal heads, and hallux. Foot pressure data has been acquired from two pediatric subjects during multiple walking trials to illustrate system application in the normal and planovalgus foot. The system is considered to be appropriate for further clinical application and for characterization of event related alterations including rehabilitative, therapeutic, surgical, and nonsurgical treatment View full abstract»

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  • 11. Biomechanical relationship between center of gravity and center of pressure during standing

    Publication Year: 1994 , Page(s): 3 - 10
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    The relationship between the position of a body's center of gravity (CG) as determined by a whole body kinematic model and that given by 3 CG position estimation techniques using the ground reaction force center of pressure (CP) has been investigated in this study. The CG and CP are related by the Newtonian mechanics equations of motion. Data required to determine directly the center of gravity position, a key variable in posture and locomotion, are usually not obtained in posture or gait trials; rather, force plate data and center of pressure data are often obtained. Consequently, previous studies have developed estimations of CG position history from CP data. The results of 3 CP-based CG estimations methods are here compared with kinematically determined CG positions in humans. The CP position varies about the CG position and has a higher frequency content than the motion of the CG. This observation, based on the authors' data and mechanics theory, provides the basis for the methods considered in this study. All current methods employ a filtering technique to obtain CG position from CP position time histories during standing trials. In most cases the mean square error is less than 0.1 cm2. Finite-duration impulse response filters with periods of 1.0 s to 1.50 s gave the best results when compared with the CG position based on kinematic data. A low-pass filter with cutoff frequency of 0.4 Hz to 0.5 Hz provides the best comparison for this approximation method. The accuracy of the methods diminishes as more dynamics are introduced to the trial. The average mean square differences for walking-in-place trials is from 1 to 10 times greater than that for the standing. CG position estimates from CP data must be interpreted cautiously when nonstatic tasks are monitored, especially in unstable patients View full abstract»

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  • 12. A microfabricated electrostatic haptic display for persons with visual impairments

    Publication Year: 1998 , Page(s): 241 - 248
    Cited by:  Papers (32)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    An electrostatic haptic display with three 7×7 electrode arrays of three different sizes was fabricated on a 4-in wafer using lithographic microfabrication techniques. The display utilizes electrostatic stimulation to generate a tactile sensation of texture on a scanning finger. The tactile sensation appeared to be a result of increased friction and vibration due to the electrostatic forces between the finger skin and the electrodes. Various spatial tactile patterns (lines, circles, squares, and triangles, etc.) can be presented on the display. Experiments of threshold, line separation, and pattern recognition were performed on subjects with visual impairments to study the spatial resolution and information transmission on arrays of variant electrode size and spacing. Two columns with two-column spacing can be resolved with 80% accuracy on the small array, for a spatial resolution of 5.8 mm in terms of edge-to-edge electrode distance. The overall percentages of correct recognition for the patterns were 68.3, 72.1, and 71.3% on the small, medium, and large arrays, respectively. While subject is an important factor for both threshold and pattern recognition, electrode size was statistically significant for threshold only. Frequency and duty cycle of the stimulation waveform did not show statistical significance View full abstract»

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  • 13. A system for the analysis of foot and ankle kinematics during gait

    Publication Year: 1996 , Page(s): 25 - 32
    Cited by:  Papers (99)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    A five-camera Vicon (Oxford Metrics, Oxford, England) motion analysis system was used to acquire foot and ankle motion data. Static resolution and accuracy were computed as 0.86±0.13 mm and 98.9%, while dynamic resolution and accuracy were 0.1±0.89 and 99.4% (sagittal plane). Spectral analysis revealed high frequency noise and the need for a filter (6 Hz Butterworth low-pass) as used in similar clinical situations, A four-segment rigid body model of the foot and ankle was developed. The four rigid body foot model segments were (1) tibia and fibula, (2) calcaneus, talus, and navicular, (3) cuneiforms, cuboid, and metatarsals, and (4) hallux. The Euler method for describing relative foot and ankle segment orientation was utilized in order to maintain accuracy and ease of clinical application. Kinematic data from a single test subject are presented View full abstract»

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  • 14. Current trends in Graz brain-computer interface (BCI) research

    Publication Year: 2000 , Page(s): 216 - 219
    Cited by:  Papers (173)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    Describes a research approach to develop a brain-computer interface (BCI) based on recognition of subject-specific EEG patterns. EEG signals recorded from sensorimotor areas during mental imagination of specific movements are classified on-line and used e.g. for cursor control. In a number of on-line experiments, various methods for EEG feature extraction and classification have been evaluated View full abstract»

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  • 15. Impact of a poka-yoke device on job performance of individuals with cognitive impairments

    Publication Year: 1998 , Page(s): 269 - 276
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    Job performance and production related issues are important not only to successful vocational training and ultimate job placement for individuals with cognitive disabilities, but also for their ability to have expanded vocational options. This study hypothesized that the application of Kaizen philosophy, and poka-yoke techniques in particular, could create job opportunities and improve productivity of individuals with cognitive disabilities. Poka-yoke or error-proofing techniques are part of the collection of Kaizen techniques. Kaizen refers to continuous improvement in performance, cost/effectiveness, and quality. Kaizen strives to empower the worker, increase worker satisfaction, facilitate a sense of accomplishment, and thereby create pride-of-work. These techniques typically reduce the physical and cognitive demands of a task and thereby render the task more accessible. The job was a fuel clamp assembly. A redesigned assembly fixture was the poka-yoke intervention. Consistent with poka-yoke principles, the intervention improved the productivity of everyone attempting the assembly. In particular, the workers in this study showed an 80% increase in productivity and an average percent error drop from 52% to about 1% after the process redesign. Furthermore, the workers showed improved morale, self-esteem, and pride-of-work. Prior to the process redesign, only the higher functioning workers could successfully perform the assembly. After the redesign a greater number of workers could successfully perform the assembly. These results not only validated the study hypothesis, but demonstrated that the success facilitated by applying Kaizen techniques had similar results with individuals with cognitive disabilities as with nondisabled workers View full abstract»

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  • 16. Brain-computer interface research at the Wadsworth Center

    Publication Year: 2000 , Page(s): 222 - 226
    Cited by:  Papers (122)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    Studies at the Wadsworth Center over the past 14 years have shown that people with or without motor disabilities can learn to control the amplitude of μ or β rhythms in electroencephalographic (EEG) activity recorded from the scalp over the sensorimotor cortex and can use that control to move a cursor on a computer screen in one or two dimensions. This EEG-based brain-computer interface (BCI) could provide a new augmentative communication technology for those who are totally paralyzed or have other severe motor impairments, Present research focuses on improving the speed and accuracy of BCI communication View full abstract»

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  • 17. Three-dimensional tactile display for the blind

    Publication Year: 1998 , Page(s): 249 - 256
    Cited by:  Papers (47)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    A tactile display device that can present tangible relief graphics for visually impaired persons has been developed. The tactile surface consists of a 64×64 arrangement of tactor-pins with 3 mm interspacing. The tactor-pins are aligned in a hexagonal, rather than a square formation, to assure smooth depiction. The matrix has a total area of 200 mm×170 mm. Each pin can be raised in 0.1 mm steps to a maximum height of 10 mm. Users can get certain information by touching the pins raised at varying heights with fingers and/or palms. Laboratory assessment of the device with six blind subjects showed its ability to transmit various kinds of information View full abstract»

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  • 18. EMG pattern recognition based on artificial intelligence techniques

    Publication Year: 1998 , Page(s): 400 - 405
    Cited by:  Papers (42)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    This paper presents an electromyographic (EMG) pattern recognition method to identify motion commands for the control of a prosthetic arm by evidence accumulation based on artificial intelligence with multiple parameters. The integral absolute value, variance, autoregressive (AR) model coefficients, linear cepstrum coefficients, and adaptive cepstrum vector are extracted as feature parameters from several time segments of EMG signals. Pattern recognition is carried out through the evidence accumulation procedure using the distances measured with reference parameters. A fuzzy mapping function is designed to transform the distances for the application of the evidence accumulation method. Results are presented to support the feasibility of the suggested approach for EMG pattern recognition View full abstract»

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  • 19. Frequency component selection for an EEG-based brain to computer interface

    Publication Year: 1999 , Page(s): 413 - 419
    Cited by:  Papers (59)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    A new communication channel for severely handicapped people could be opened with a direct brain to computer interface (BCI). Such a system classifies electrical brain signals online. In a series of training sessions, where electroencephalograph (EEG) signals are recorded on the intact scalp, a classifier is trained to discriminate a limited number of different brain states. In a subsequent series of feedback sessions, where the subject is confronted with the classification results, the subject tries to reduce the number of misclassifications. In this study the relevance of different spectral components is analyzed: (1) on the training sessions to select optimal frequency bands for the feedback sessions and (2) on the feedback sessions to monitor changes View full abstract»

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  • 20. Fuzzy EMG classification for prosthesis control

    Publication Year: 2000 , Page(s): 305 - 311
    Cited by:  Papers (111)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Proposes a fuzzy approach to classify single-site electromyograph (EMG) signals for multifunctional prosthesis control. While the classification problem is the focus of this paper, the ultimate goal is to improve myoelectric system control performance, and classification is an essential step in the control. Time segmented features are fed to a fuzzy system for training and classification. In order to obtain acceptable training speed and realistic fuzzy system structure, these features are clustered without supervision using the Basic Isodata algorithm at the beginning of the training phase, and the clustering results are used in initializing the fuzzy system parameters. Afterwards, fuzzy rules in the system are trained with the back-propagation algorithm. The fuzzy approach was compared with an artificial neural network (ANN) method on four subjects, and very similar classification results were obtained. It is superior to the latter in at least three points: slightly higher recognition rate; insensitivity to overtraining; and consistent outputs demonstrating higher reliability. Some potential advantages of the fuzzy approach over the ANN approach are also discussed View full abstract»

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  • 21. The effects of self-movement, observation, and imagination on μ rhythms and readiness potentials (RP's): toward a brain-computer interface (BCI)

    Publication Year: 2000 , Page(s): 219 - 222
    Cited by:  Papers (62)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    Current movement-based brain-computer interfaces (BCI's) utilize spontaneous electroencephalogram (EEG) rhythms associated with movement, such as the μ rhythm, or responses time-locked to movements that are averaged across multiple trials, such as the readiness potential (RP), as control signals. In one study, the authors report that the μ rhythm is not only modulated by the expression of self-generated movement but also by the observation and imagination of movement. In another study, the authors show that simultaneous self-generated multiple limb movements exhibit properties distinct from those of single limb movements. Identification and classification of these signals with pattern recognition techniques provides the basis for the development of a practical BCI. View full abstract»

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  • 22. A model for human skin impedance during surface functional neuromuscular stimulation

    Publication Year: 1999 , Page(s): 341 - 348
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    A new mathematical model for the bulk electrical impedance of human skin is presented. In particular this model describes the impedance of skin during surface functional neuromuscular stimulation (FNS) with square stimulation pulses. Experimental data are presented that illustrate the nonlinear dynamic properties of human skin during current and voltage controlled stimulation. Model predictions are compared to experimental data, measured under both constant voltage and constant current transcutaneous stimulation. It is found that this model captures a variety of nonlinear time-varying effects observed in the skin impedance when stimulating with either protocol. This model may be used as part of large neuromusculoskeletal models or in the more accurate modeling of transcutaneous FNS, which is currently the most common clinical implementation of FNS View full abstract»

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  • 23. EEG-based communication: a pattern recognition approach

    Publication Year: 2000 , Page(s): 214 - 215
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (24 KB)  

    Presents an overview of the authors' research into brain-computer interfacing (BCI). This comprises an offline study of the effect of motor imagery on EEG and an online study that uses pattern classifiers incorporating parameter uncertainty and temporal information to discriminate between different cognitive tasks in real-time View full abstract»

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  • 24. Using time-dependent neural networks for EEG classification

    Publication Year: 2000 , Page(s): 457 - 463
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    This paper compares two different topologies of neural networks. They are used to classify single trial electroencephalograph (EEG) data from a brain-computer interface (BCI). A short introduction to time series classification is given, and the used classifiers are described. Standard multilayer perceptrons (MLPs) are used as a standard method for classification. They are compared to finite impulse response (FIR) MLPs, which use FIR filters instead of static weights to allow temporal processing inside the classifier. A theoretical comparison of the two architectures is presented. The results of a BCI experiment with three different subjects are given and discussed. These results demonstrate the higher performance of the FIR MLP compared with the standard MLP View full abstract»

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  • 25. A review of design issues in rehabilitation robotics with reference to North American research

    Publication Year: 1995 , Page(s): 3 - 13
    Cited by:  Papers (13)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1600 KB)  

    Since rehabilitation robotics is a small field, progress toward useful devices will be faster if research groups are cognizant of the successes and failures that have been made in the past. The authors review past and present work, focusing on projects in North America (a companion paper in this issue reviews work in Europe), and attempts to identify the key features that have led to the success or failure of devices. Of particular note is the reliance in the past on position controlled robots, as these were the available level of technology. Lack of exemplar products has made it difficult for researchers to identify the needs and expectations that a person with a physical disability might have of a rehabilitation robot. This situation is changing rapidly and the field can now benefit from “consumer in the loop” research and design methods View full abstract»

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  • 26. Wavelet and short-time Fourier transform analysis of electromyography for detection of back muscle fatigue

    Publication Year: 2000 , Page(s): 433 - 436
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    Measurement of the time-varying characteristics of the frequency content of trunk muscle electromyography is a method to quantify the amount of fatigue endured by workers during industrial tasks, as well as a tool that may guide the training and rehabilitation of healthy and injured workers. Quantification of the change of signal power within specific frequency ranges may shed greater insight into the fatigue process. Sixteen healthy male subjects performed isometric trunk extension at 70% of their maximum voluntary contraction. Surface electromyography from medial and lateral erector spinae, and latissimus dorsi locations were processed using the short-time Fourier transform (STFT) and wavelet transform. Linear regression quantified the time rate of change of median frequency as well as frequency specific STFT filter and wavelet scale measures. The median frequency from the short-time Fourier transform declined by 22 Hz/min from an initial value of 77 Hz on average. The wavelet and STFT filter measures demonstrated this decline to be caused by a reduction in 209-349 Hz signal power in addition to an increase in 7-88 Hz signal power. A significant reduction in median frequency and significant elevation in 13-22 Hz wavelet signal component was detected in about 90% of the cases, indicating their use for detecting and quantifying fatigue View full abstract»

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  • 27. Interface mechanics in lower-limb external prosthetics: a review of finite element models

    Publication Year: 1996 , Page(s): 288 - 302
    Cited by:  Papers (6)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1832 KB)  

    The distribution of mechanical stress at the interface between a residual limb and prosthetic socket is an important design consideration in lower-limb prosthetics. Stresses must be distributed so that the amputee is stable and comfortable, while avoiding trauma to the tissues of the residual limb. Numerical estimation of the stresses at the interface through finite element (FE) modeling can potentially provide researchers and prosthetists with a tool to aid in the design of the prosthetic socket. This review addresses FE modeling of interface stresses in lower-limb external prosthetics. The modeling methodologies adopted by analysts are described. Verification of FE estimates of interface stress against experimental data by different analysts is presented and the likely sources of error discussed. While the performance of the models is encouraging, there are definite limitations to all of them, necessitating further improvements. Parametric analysis of the sensitivity of interface stress to model parameters provides a tool to identify model weaknesses and to suggest possible refinements. Parametric analyses by different analysts are also presented and potential refinements discussed. Finally, directions for future work in prosthetic FE modeling are suggested View full abstract»

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  • 28. The NavChair Assistive Wheelchair Navigation System

    Publication Year: 1999 , Page(s): 443 - 451
    Cited by:  Papers (107)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    The NavChair Assistive Wheelchair Navigation System is being developed to reduce the cognitive and physical requirements of operating a power wheelchair for people with wide ranging impairments that limit their access to powered mobility. The NavChair is based on a commercial wheelchair system with the addition of a DOS-based computer system, ultrasonic sensors, and an interface module interposed between the joystick and power module of the wheelchair. The obstacle avoidance routines used by the NavChair in conjunction with the ultrasonic sensors are modifications of methods originally used in mobile robotics research. The NavChair currently employs three operating modes: general obstacle avoidance, door passage, and automatic wall following. Results from performance testing of these three operating modes demonstrate their functionality. In additional to advancing the technology of smart wheelchairs, the NavChair has application to the development and testing of “shared control” systems where a human and machine share control of a system and the machine can automatically adapt to human behaviors View full abstract»

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  • 29. Electronic design of a cochlear implant for multichannel high-rate pulsatile stimulation strategies

    Publication Year: 1995 , Page(s): 112 - 116
    Cited by:  Papers (34)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    A new electronic design for an eight-channel cochlear implant for high-rate pulsatile stimulation strategies is presented. Symmetric biphasic current pulses can be generated up to a maximum pulse repetition rate of about 12 kpulses/s. The stimulation pulse amplitude can be selected within the range of 1.5 μA-1.5 mA. The implant contains a single mixed analog/digital CMOS-ASIC for data synchronization and stimulus generation. Stimulation signals are applied via a monopolar intracochlear multielectrode array. Output capacitors are employed for safety reasons. A back-telemetry system for measuring electrode voltages and the implant supply voltage is incorporated. Data and power are transcutaneously transferred to the implant, using a single rf-channel. The overall data rate is 400 kb/s View full abstract»

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  • 30. A nonlinear mathematical model of electrically stimulated skeletal muscle

    Publication Year: 1997 , Page(s): 179 - 194
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    A new biophysically based mathematical model for a human musculotendon system is presented. This model is developed specifically for skeletal muscle activated by functional electrical stimulation (FES). The reverse-order recruitment dynamics of PES activated systems are modeled, as are the underlying processes of force generation in mammalian muscle. The resulting system model is both nonlinear and highly coupled, reflecting the fundamental structure and behavior of skeletal muscle. A new heterogeneous model structure for a contractile element is also presented that overcomes many of the problems which arise when attempting to describe all possible contraction modes. It is found that the new model is robust, numerically stable, and easily implemented. Simulation results are presented that demonstrate the model's ability to capture a variety of nonlinear behaviors observed in skeletal muscle activated by FES. Significant insight into the internal dynamics of force development in FES muscle may also be gained from the model. This model is intended as a possible alternative to those currently available in the literature. It may be of use to those conducting research into the modeling, control and optimization of FES generated motion, and neural feedback systems View full abstract»

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  • 31. Detection of static and dynamic activities using uniaxial accelerometers

    Publication Year: 1996 , Page(s): 375 - 385
    Cited by:  Papers (74)  |  Patents (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1168 KB)  

    Rehabilitation treatment may be improved by objective analysis of activities of daily living. For this reason, the feasibility of distinguishing several static and dynamic activities (standing, sitting, lying, walking, ascending stairs, descending stairs, cycling) using a small set of two or three uniaxial accelerometers mounted on the body was investigated. The accelerometer signals can be measured with a portable data acquisition system, which potentially makes it possible to perform online detection of static and dynamic activities in the home environment. However, the procedures described in this paper have yet to be evaluated in the home environment. Experiments were conducted on ten healthy subjects, with accelerometers mounted on several positions and orientations on the body, performing static and dynamic activities according to a fixed protocol. Specifically, accelerometers on the sternum and thigh were evaluated. These accelerometers were oriented in the sagittal plane, perpendicular to the long axis of the segment (tangential), or along this axis (radial). First, discrimination between the static or dynamic character of activities was investigated. This appeared to be feasible using an rms-detector applied on the signal of one sensor tangentially mounted on the thigh. Second, the distinction between static activities was investigated. Standing, sitting, lying supine, on a side and prone could be distinguished by observing the static signals of two accelerometers, one mounted tangentially on the thigh, and the second mounted radially on the sternum. Third, the distinction between the cyclical dynamic activities walking, stair ascent, stair descent and cycling was investigated. The discriminating potentials of several features of the accelerometer signals were assessed: the mean value, the standard deviation, the cycle time and the morphology. Signal morphology was expressed by the maximal cross-correlation coefficients with template signals for the different dynamic activities. The mean signal values and signal morphology of accelerometers mounted tangentially on the thigh and the sternum appeared to contribute to the discrimination of dynamic activities with varying detection performances. The standard deviation of the signal and the cycle time were primarily related to the speed of the dynamic activities, and did not contribute to the discrimination of the activities. Therefore, discrimination of dynamic activities on the basis of the combined evaluation of the mean signal value and signal morphology is proposed View full abstract»

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  • 32. Application of tilt sensors in functional electrical stimulation

    Publication Year: 1996 , Page(s): 63 - 72
    Cited by:  Papers (59)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    Tilt sensors, or inclinometers have been investigated for the control of functional electrical stimulation (FES) to improve the gait of persons who had a stroke or incomplete spinal cord injury (SCI). Different types of tilt sensors were studied for their characteristics and their performance in measuring the angular displacement of leg segments during gait. Signal patterns of the lower leg with inertial tilt sensors were identified with control subjects and subjects with footdrop who are being stimulated during level walking. To minimize acceleration responses when the foot swings or hits the ground, we use low-pass filtering (1.5-2 Hz). A finite state approach allows the sensor fixed on the shank to effectively detect the step intention in a population of stroke and incomplete SCI subjects and to control the FES. When the lower leg tilts backward, the common peroneal nerve is stimulated to bring the foot up and forward. We have designed a miniature footdrop stimulator with a magnetoresistive tilt sensor built in, so no external sensor cables are required. The thresholds to turn the stimulator on and off can be adjusted, as well as the maximum period of stimulation and the minimum interval between periods of stimulation. This device features several important advantages over traditional AFO's or stimulators controlled by foot switches. Initial trials with stroke and SCI subjects have demonstrated substantial gait improvement for some subjects, while most liked the good cosmesis and ease of using the device with a tilt sensor View full abstract»

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  • 33. The new design of an infrared-controlled human-computer interface for the disabled

    Publication Year: 1999 , Page(s): 474 - 481
    Cited by:  Papers (34)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    This paper reports on the development of an eyeglass-type infrared (IR)-controlled computer interface for the disabled. This system may serve to assist those who suffer from spinal cord injuries or other handicaps to operate a computer. This system is comprised of three major components: 1) an infrared transmitting module, 2) an infrared receiving/signal-processing module, and 3) a main controller, the Intel-8951 microprocessor. The infrared transmitting module utilizes tongue-touch circuitry which is converted to an infrared beam and a low power laser (<0.1 mW) beam. The infrared receiving/signal-processing module, receives the infrared beam and fine tunes the unstable infrared beam into standard pulses which are used as control signals. The main controller is responsible for detecting the input signals from the infrared receiving/signal-processing module and verifying these signals with the mapping table in its memory. After the signal is verified, it is released to control the keys of the computer keyboard and mouse interface. This design concept was mainly based on the idea that the use of an infrared remote module fastened to the eyeglasses could allow the convenient control of the input motion on the keys of a computer keyboard and mouse which are all modified with infrared receiving/signal-processing modules. The system is designed for individuals with spinal cord injuries and disabled in which the subjects' movement are severely restricted. The infrared transmitting module can be easily mounted on eyeglasses or artificial limbs View full abstract»

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  • 34. The thought translation device (TTD) for completely paralyzed patients

    Publication Year: 2000 , Page(s): 190 - 193
    Cited by:  Papers (141)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    The thought translation device trains locked-in patients to self regulate slow cortical potentials (SCP's) of their electroencephalogram (EEG). After operant learning of SCP self control, patients select letters, words or pictograms in a computerized language support program. Results of five respirated, locked-in-patients are described, demonstrating the usefulness of the thought translation device as an alternative communication channel in motivated totally paralyzed patients with amyotrophic lateral sclerosis View full abstract»

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  • 35. Analysis of muscle coordination strategies in cycling

    Publication Year: 2000 , Page(s): 362 - 370
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    The functional significance of the stereotypical muscle activation patterns used in skilled multi-joint tasks is not well understood. Optimization methods could provide insight into the functional significance of muscle coordination. The purpose of this study was to predict muscle force patterns during cycling by pushing and pulling the pedal using different optimization criteria and compare the predictions with electromyographic (EMG) patterns. To address the purpose of the study, (1) the contribution of muscle length and velocity changes to EMG-muscle force relationships during cycling was examined by comparing joint moments calculated from EMG and inverse dynamics, (2) patterns of individual muscle forces during cycling of five subjects were predicted using 13 different optimization criteria, and (3) the properties of the criterion with the best performance in predicting the normalized EMG were used to explain the features and functional significance of muscle coordination in cycling. It was shown that the criterion that minimizes the sum of muscle stresses cubed demonstrated the best performance in predicting the relative magnitude and patterns of muscle activation. Based on this criterion, it was suggested that the functional significance of muscle coordination strategy in cycling may be minimization of fatigue and/or perceived effort View full abstract»

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  • 36. Feedback error learning neural network for trans-femoral prosthesis

    Publication Year: 2000 , Page(s): 71 - 80
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Feedback-error learning (FEL) neural network was developed for control of a powered trans-femoral prosthesis. Nonlinearities and time-variations of the dynamics of the plant, in addition to redundancy and dynamic uncertainty during the double support phase of walking, makes conventional control methods very difficult to use. Rule-based control, which uses a knowledge base determined by machine learning and finite automata method is limited since it does not respond well to perturbations and environmental changes. FEL can be regarded as a hybrid control, because it combines nonparametric identification with parametric modeling and control. This paper presents simulation of a powered trans-femoral prosthesis controlled by a FEL neural network. Results suggest that FEL can be used to identify inverse dynamics of an arbitrary trans-femoral prosthesis during simple single joint movements (e.g., sinusoidal oscillations). The identified inverse dynamics then allows the tracking of an arbitrary trajectory such as a desired walking pattern within a multijoint structure. Simulation shows that the identified controller responds correctly when the leg motion is exposed to a perturbation such as a frequent change of the ground reaction force or the hip joint torque generated by the user. FEL eliminates the need for precise, tedious, and complex identification of model parameters View full abstract»

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  • 37. MARCUS: a two degree of freedom hand prosthesis with hierarchical grip control

    Publication Year: 1995 , Page(s): 70 - 76
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB)  

    An important factor in the acceptance of a prosthesis is the ease with which the wearer can operate the device. Multiple degrees of freedom of a prosthesis are difficult to control independently and require a high level of concentration. If the control is arranged in a hierarchical manner and the lower levels' detailed control is performed by a microprocessor, it is possible to control a number of degrees with little direct intervention by the operator. A two degree of freedom hand has been developed to demonstrate this concept and has been made sufficiently compact to allow users to gain experience with it View full abstract»

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  • 38. Three-dimensional kinematics of wheelchair propulsion

    Publication Year: 1996 , Page(s): 152 - 160
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB)  

    A three-dimensional (3-D biomechanical model was used to determine upper extremity kinematics of 16 male subjects with low-level paraplegia while performing wheelchair propulsion (WCP). A six-camera VICON motion analysis system was used to acquire the coordinate data of ten anatomic markers. Joint axes for the wrist and elbow were defined along with the planes of motion for the upper arm (humerus) and trunk. The group's mean and standard deviation profiles were graphed for eight of the nine rotations measured during WCP. Variability in the intercycle and intersubject movement patterns were calculated using the root mean square standard deviation (RMSσ) and the coefficient of variation (CV). Motion pattern similarities were quantified using the coefficient of multiple correlation (CMC). The intercycle (Nc⩾6) motion patterns of individual subjects were highly consistent, similar, and repeatable during WCP. This was confirmed by low CVc values (3-31%), high CMCc values (0.724-0.996) and RMSσ c values below 3.2°. For the group, mean values of the propulsion velocity, cadence, and propulsion cycle duration were 89.7 m/min, 66.1 pushes/min, and 0.96 s, respectively. Humeral plane and rotation showed large excursions (76.1-81.6°), while trunk lean and forearm carrying angle displayed relatively small ranges of motion (5.5-10.9°). The intersubject N3=16) motion patterns were less similar compared to individual intercycle patterns. This was evidenced by higher CV3 values (12-128%) and lower CMC3 values (0.418-0.935). Intersubject humeral patterns were the most consistent while trunk lean was the least consistent. Intersubject root mean square standard deviations (RMSσ3) were more than three times the corresponding intercycle values for all nine rotations View full abstract»

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  • 39. Patient-driven control of FES-supported standing up and sitting down: experimental results

    Publication Year: 2000 , Page(s): 523 - 529
    Cited by:  Papers (21)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    A patient driven control strategy for standing-up and sitting-down was experimentally tested on two paraplegic patients by applying functional electrical stimulation (FES) to the quadriceps muscle. The strategy-also known as “patient-driven motion reinforcement” (PDMR)-was developed by computer simulations reported in a former study. It is based on an inverse dynamic model (IDM) that predicts the stimulation pattern required to maintain the movement as it is initiated by the patient's voluntary effort. For reasons of safety and weight relief, the movement was supported by a seesaw construction. After some practice the patients were able to influence the stimulator output and to control the movement by their voluntary effort. Consequently, no pre-programmed reference trajectory was required. As a positive side effect, upper body effort could be minimized compared to trials without FES. To achieve a satisfactory performance of the PDMR controller a careful parameter identification of the inverse dynamic model was fundamental View full abstract»

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  • 40. Estimating mechanical parameters of leg segments in individuals with and without physical disabilities

    Publication Year: 1996 , Page(s): 201 - 211
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1160 KB)  

    Methods are described for estimating the inertia, viscosity, and stiffness of the lower leg around the knee and of the whole leg around the hip that are applicable even to persons with considerable spasticity. These involve: (1) a “pull” test in which the limb is slowly moved throughout its range of motion while measuring angles (with an electrogoniometer) and torques (with a hand-held dynamometer) to determine passive stiffness and (2) a “pendulum” test in which the limb is moved against gravity and then dropped, while again measuring angles and torques. By limiting the extent of the movement and choosing a direction (flexion or extension) that minimizes reflex responses, the mechanical parameters can be determined accurately and efficiently using computer programs. In the sample of subjects studied (nine with disability related to spinal cord injury, head injury, or stroke, and nine with no neurological disability), the inertia of the lower leg was significantly reduced in the subjects with disability (p<0.05) as a result of atrophy, but the stiffness and viscosity were within normal limits. The values of inertia were also compared with anthropometric data in the literature. The identification of these passive parameters is particularly important in designing systems for functional electrical stimulation of paralyzed muscles, but the methods may be widely applicable in rehabilitation medicine View full abstract»

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  • 41. An approach to a muscle model with a stimulus frequency-force relationship for FES applications

    Publication Year: 1999 , Page(s): 12 - 18
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    A simplified model of electrically stimulated muscle for use in applications of functional electrical stimulation (FES) is discussed in this paper. The muscle model was required to have both stimulus frequency and stimulus intensity (amplitude/width) inputs. The stimulus frequency versus force relationship of rabbit muscle was modeled first with a small number of model parameters that could be identified by simple experiments in a short time. The model identified was found to be applicable to human muscles. The frequency-force relationships of electrically stimulated fast and slow type muscles were also predicted by the model. The frequency-force model and a simplified model of muscle activation dynamics were used to construct a muscle model that described the summation of muscle contraction. The use of this model decreased the time burden on patients during parameter identification at the clinical site. The clinical applicability of these new model descriptions was suggested through computer simulations View full abstract»

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  • 42. Optical recognition of Braille writing using standard equipment

    Publication Year: 1994 , Page(s): 207 - 212
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    The reproduction of Braille writing has been, up until now, a purely manual job. To overcome this problem, many researchers have tried to develop a Braille reading machine in some way or another. Their efforts have not given a satisfying solution. The goal of the research described in this text is to develop a system that converts, within acceptable constraints, Braille (image) to a computer readable form (text). Having the text on a computer, a Braille printing house can reproduce it using an electronic Braille embosser View full abstract»

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  • 43. Improving the efficacy of electrical stimulation-induced leg cycle ergometry: an analysis based on a dynamic musculoskeletal model

    Publication Year: 1993 , Page(s): 109 - 125
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1624 KB)  

    To improve the design and increase the effectiveness of electrical stimulation-induced leg cycle ergometry, it is necessary to have a better understanding of the factors that influence the force production capabilities of the stimulated muscles, the ability of the muscles to produce the desired movement, and the metabolic demands of the contractions. A dynamic musculoskeletal model capable of simulating a spinal cord injured (SCI) person exercising on a stimulation-powered leg cycle ergometer was developed to explore these issues. This model was used to address the concern whether performance can be improved by changing seat configuration, the loading, or the intermuscle stimulation pattern. Performance was assessed in terms of the probability that a given SCI subject would be able to maintain a steady cadence, the relative strength required by each muscle group to pedal alone, and the estimated rate of metabolic energy utilization associated with steady-state pedaling. The authors considered the sensitivity of the model predictions to intersubject variability. Several strategies are suggested for either minimizing the strength needed to pedal, or maximizing the cardiovascular aerobic exercise View full abstract»

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  • 44. EMG-based prediction of shoulder and elbow kinematics in able-bodied and spinal cord injured individuals

    Publication Year: 2000 , Page(s): 471 - 480
    Cited by:  Papers (50)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    The authors have evaluated the ability of a time-delayed artificial neural network (TDANN) to predict shoulder and elbow motions using only electromyographic (EMG) signals recorded from six shoulder and elbow muscles as inputs, both in able-bodied subjects and in subjects with tetraplegia arising from C5 spinal cord injury. For able-bodied subjects, all four joint angles (elbow flexion-extension and shoulder-horizontal flexion-extension, elevation depression, and internal-external rotation) were predicted with average root-mean-square (rms) errors of less than 20° during movements of widely different complexities performed at different speeds and with different hand loads. The corresponding angular velocities and angular accelerations were predicted with even lower relative errors. For individuals with C5 tetraplegia, the absolute rms errors of the joint angles, velocities, and accelerations were actually smaller than for able-bodied subjects, but the relative errors were similar when the smaller movement ranges of the C5 subjects were taken into account. These results indicate that the EMG signals from shoulder and elbow muscles contain a significant amount of information about arm movement kinematics that could be exploited to develop advanced control systems for augmenting or restoring shoulder and elbow movements to individuals with tetraplegia using functional neuromuscular stimulation of paralyzed muscles View full abstract»

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  • 45. Design of a haptic data visualization system for people with visual impairments

    Publication Year: 1999 , Page(s): 372 - 384
    Cited by:  Papers (36)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    Data visualization is a technique used to explore real or simulated data by representing it in a form more suitable for comprehension. This form is usually visual since vision provides a means to perceive large quantities of spatial information quickly. However, people who are blind or visually impaired must rely on other senses to accomplish this perception. Haptic interface technology makes digital information tangible, which can provide an additional medium for data exploration and analysis. Unfortunately, the amount of information that can be perceived through a haptic interface is considerably less than that which can be perceived through vision, so a haptic environment must be enhanced to aid the comprehension of the display. This enhancement includes speech output and the addition of object properties such as friction and texture. Textures are generated which can be modified according to a characteristic or property of the object to which it is applied. For example, textures can be used as an analog to color in graphical displays to highlight variations in data. Taking all of these factors into account, methods for representing various forms of data are presented here with the goal of providing a haptic visualization system without the need for a visual component. The data forms considered include one-, two-, and three-dimensional (1-D, 2-D, and 3-D) data which can be rendered using points, lines, surfaces, or vector fields similar to traditional graphical displays. The end result is a system for the haptic display of these common data sets which is accessible for people with visual impairments View full abstract»

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  • 46. A new technique for the calculation of the energy stored, dissipated, and recovered in different ankle-foot prostheses

    Publication Year: 1994 , Page(s): 247 - 255
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (764 KB)  

    Previous research reported calculation of mechanical power of ankle-foot devices using the dot product of the ankle moment times the ankle angular velocity. Unfortunately, there are two errors in this analysis technique. The biomechanical model used assumed a rigid foot articulating around the ankle and there was no accounting for energy storage or dissipation and recovery in the viscoelastic material of the cosmetic cover. The first purpose of this paper is to propose a rigorous technique for the calculation of the net energy efficiency that could be used for any articulated or nonarticulated ankle-foot prosthesis. The second purpose is to quantify the amount of energy stored or dissipated and then recovered in order to discriminate between different ankle-foot prostheses. The SACH, Seattle, Flex-foot, and Golden-Ankle ankle-foot prostheses; were evaluated on the same amputee, while walking at his natural cadence. The power entering and leaving the distal end of the prosthetic leg was calculated as the sum of the translational (force-velocity product) and rotational (moment-angular velocity product). All ankle-foot prostheses showed the same distal power pattern. After initial contact, a large energy storage was observed in the cushioned heel, which was followed by some energy recovery. Then, during mid and late stance, another period of storage or dissipation and recovery was observed. Even the SACH foot should be considered an energy storing foot prosthesis since it's cosmetic material was seen to be capable of recovering energy. The balance between the rate of change of foot mechanical energy and the foot powers showed that the new technique takes into account the energy stored or dissipated and then recovered within the compliant material and flexing keel. The new analysis technique can be used by prosthetic designers to assess any type of ankle-foot prostheses. Criteria for ankle-foot prosthesis selection should include, not only the net mechanical efficiency for both rearfoot and forefoot sections, but also, the total energy recovered by the ankle-foot prostheses View full abstract»

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  • 47. Muscle balance at the knee-moment arms for the normal knee and the ACL-minus knee

    Publication Year: 1997 , Page(s): 367 - 379
    Cited by:  Papers (50)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    Forces, moments and stresses at the knee are dependent upon external and internal loading factors including muscle forces, segmental position and velocity, load carried, and the moment arms (mechanical advantage) of the muscle-tendon units. Requisite to prediction of forces and moments is a detailed understanding of effective moment arms throughout the knee range-of-motion (ROM). Existing muscle models for the knee are based upon limited static studies of only a few preserved specimens. The objectives of this report are to develop a comprehensive description of muscle-tendon moment arms for the normal knee and the anterior cruciate ligament (ACL)-minus knee during flexion-extension motion. Recent research results describe two nonorthogonal, nonintersecting axes of motion for the knee-one describing flexion-extension (FE) and the other longitudinal rotation (LR, equivalent to internal-external rotation). The effective flexion-extension moment arms of the muscles crossing the knee were developed with respect to the FE axis in 15 fresh, hemi-pelvis cadaver specimens. The normal moment arms for each of 13 muscles plus the patellar tendon exhibited variable, yet repeatable and recognizable patterns throughout the ROM. For most muscles there was no significant difference between the normal and ACL-minus moment arms. The results provide a basis for more accurate predictions of joint reaction forces and moments as well as useful knowledge for practitioners and therapists to assist in the assessment of muscle balance at the knee following injury, repair, and throughout rehabilitation View full abstract»

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  • 48. A direct brain interface based on event-related potentials

    Publication Year: 2000 , Page(s): 180 - 185
    Cited by:  Papers (86)  |  Patents (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Cross-correlation between a trigger-averaged event-related potential (ERP) template and continuous electrocorticogram was used to detect movement-related ERP's. The accuracy of ERP detection for the five best subjects (of 17 studied), had hit percentages >90% and false positive percentages <10%. These cases were considered appropriate for operation of a direct brain interface View full abstract»

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  • 49. Automatic visual to tactile translation. I. Human factors, access methods and image manipulation

    Publication Year: 1997 , Page(s): 81 - 94
    Cited by:  Papers (24)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    This is the first part of a two-part paper that motivates and evaluates a method for the automatic conversion of images from visual to tactile form. In this part, a broad-ranging background is provided in the areas of human factors, including the human sensory system, tactual perception and blindness, access technology for tactile graphics production, and image processing techniques and their appropriateness to tactile image creation. In Part II, this background is applied in the development of the TACTile Image Creation System (TACTICS), a prototype for an automatic visual-to-tactile translator. The results of an experimental evaluation are then presented and discussed, and possible future work in this area is outlined View full abstract»

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  • 50. Fuzzy clustering of children with cerebral palsy based on temporal-distance gait parameters

    Publication Year: 1997 , Page(s): 300 - 309
    Cited by:  Papers (45)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Temporal-distance parameters for 88 children with the spastic diplegia form of cerebral palsy (CP) are grouped using the fuzzy clustering paradigm. The 2 features chosen for clustering are stride length and cadence which are normalized for age and leg length using a model based on a population of 68 neurologically intact children. Using information provided by the neurologically intact population and cluster validity techniques, 5 clusters for the children with cerebral palsy are identified. The 5 cluster centers represent distinct walking strategies adopted by children with cerebral palsy. Utilizing just four easily obtained parameters-stride length, cadence, leg length and age-and a small number of simple equations, it is possible to classify any child with spastic diplegia and to generate an individual's membership values for each of the 5 clusters. The clinical utility of the fuzzy clustering approach is demonstrated with pre- and post-operative test data for subjects with cerebral palsy (one neurosurgical and one orthopaedic) where changes in membership of the 5 clusters provide an objective technique for measuring improvement. This approach can be adopted to study other clinical entities where different cluster centers would be established using the algorithm provided here View full abstract»

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Aims & Scope

This Transaction ceased publication in 2000. The current retitled publication is IEEE Transactions on Neural Systems and Rehabiliation Engineering.

Full Aims & Scope