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Rehabilitation Engineering, IEEE Transactions on

Issue 4 • Date Dec 1994

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Displaying Results 1 - 10 of 10
  • Low frequency pulsed current and pressure ulcer healing

    Page(s): 225 - 233
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    In spite of the extensive clinical work reported in the area of electrical wound healing, electrical stimulation to augment chronic wound repair is still far from being widely accepted in clinical practice. Problems in designing clinical studies (size of the sample observed, control group, ethics of the procedure), evaluating treatment efficacy, rationales for use of the treatment, and unknown underlying mechanisms contribute to the aforementioned fact. In the present study, the authors evaluated low frequency electrical current for its beneficial effects in pressure ulcer management. Seventy-three spinal cord injured patients with 109 pressure ulcers participated in the study. Patients were randomly assigned to a control group receiving conventional treatment of their ulcers, or to a stimulation group, in which the ulcers were additionally treated with low frequency pulsed current. A comparison of the two groups showed significantly higher average healing rate for the stimulated group. Patients from the control group had the opportunity of crossing over to the stimulation group after the required control period of four weeks. This group (the crossover group) was analyzed separately. In all but one ulcer out of 20, an improvement in the healing process was observed after electrical stimulation was initiated View full abstract»

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  • Wheelchair impact response to ISO test pendulum and ISO standard curb

    Page(s): 240 - 246
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    If a product is to be certified by a national or international organization, it must undergo and pass a series of standardized tests. Standards are required to establish minimum performance and durability criteria for wheelchairs. Standards benefit consumers, manufacturers, and third party providers. Testers have expressed concern over the difficulty of properly conducting the current impact test for wheelchair casters and footrests. An alternative method for impact testing of the casters and footrests may incorporate use of the handrim impact test pendulum. This paper derives the center of percussion and provides an accurate description of the pendulum, and presents experimental results of impact accelerations measured using a curb and pendulum. Linear regression analysis was used to develop equations relating impact resultant acceleration to pendulum angle for each test case (i.e., caster impact, front footrest impact, side footrest impact). ANOVA was also used to examine differences in impact resultant accelerations among the wheelchairs. Pendulum impact angle was significantly correlated with impact resultant acceleration for caster impact (r=0.58, p=0.0001), for front footrest impact (r=0.58, p=0.0004), and for footrest side impact (r=0.42, p=0.0114), The curb impact test yielded a mean for all the wheelchairs' maximum resultant impact accelerations of 7.4±2.09 g for caster contact, and 16.2±5.68 g for footrest contact. The mean equivalent pendulum release angle (i.e., the approximate pendulum angle equivalent to the curb impact accelerations) mere 24.4±1.95 degrees for castor contact, 33.8±4.80 degrees for frontal footrest contact, and 39.3±3.05 degrees for side footrest contact. The authors' results indicate that the standard deviation in maximal resultant acceleration is about 25% between trials for each wheelchair using the curb impact method, whereas the standard deviation is about 10% using the pendulum method. This indicates that the pendulum method may be more repeatable. Differences in impact strength between wheelchairs can be detected by the pendulum impact tests, which is an indication that these tests may be useful in evaluating wheelchair quality View full abstract»

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  • Neural network generation of muscle stimulation patterns for control of arm movements

    Page(s): 213 - 224
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    The authors present a new approach to the control of point-to-point, single joint arm movements by an artificial neural network (ANN) controller. The ANN controller was used to learn and store the optimal patterns of muscle stimulation for a range of single joint movements. These stimulation patterns were obtained from an optimal control strategy that minimizes muscle activation or muscular effort. Feedforward, recurrent feedback, and time delay topologies of neural networks were considered for this application. The choice of a network structure was based on the learning performance and ability to generalize a learned muscle simulation pattern to novel movements. A comparison showed that the feedforward network combined with recurrent feedback and input time delays can most effectively capture the optimal temporal profiles of muscle stimulation. This neural network controller further demonstrated remarkable ability to generalize the learned optimal control to a class of scaled movements. The authors also evaluated open-loop performance of movement control by the ANN with a nonlinear muscle/joint model. The trained neural network controller reproduced the range of scaled optimal movements well, though sometimes with terminal position errors. This study showed that neural networks were promising as an open-loop pattern generator for muscle stimulation signals in movement restoration by functional electrical stimulation View full abstract»

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  • Integrated speech training system for hearing impaired

    Page(s): 189 - 196
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    Hearing impaired people have serious difficulties learning to produce intelligible speech. To facilitate speech training for hearing impaired people, many researchers have developed various speech training aids, such as F0 (fundamental frequency) indicator, N (nasality) indicator, S (fricative /s/) indicator, and spectra displayer. However, most of these training aids treat only a single speech parameter. An integrated speech training system was implemented. The system makes it possible to display vocal tract shape, as well as other speech parameters, in real time. A self-training program for hearing impaired persons has been developed to help them correct errors. To estimate speech parameters, it is assumed that the speech production process is an autoregressive model. Using a linear predictive analysis, vocal tract lateral shapes and log spectra are estimated. Log energy of the speech signal is used as intensity. Fundamental frequency and nasality are also detected using a vibration sensor. To check the reliability of the developed system, parameters of normal people were tested and training tests for hearing impaired children were performed. The results showed that the authors' proposed system is very useful for speech training of the hearing impaired View full abstract»

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  • Independence of pitch and loudness of an electrocutaneous stimulus for sensory feedback

    Page(s): 197 - 206
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    Three experiments were performed to determine if: 1) perceived intensity (loudness) is dependent on stimulus frequency, and 2) perceived pitch is dependent on stimulus amplitude for an electrocutaneous stimulus used for sensory feedback. The electrocutaneous stimuli consisted of repetitive bursts of rectangular, charge-balanced, biphasic pulses applied through a concentric surface electrode on the lateral aspect of the upper arm. In the first experiment, subjects matched the pitch of two electrocutaneous stimuli with different charges (per pulse phase). In the second and third experiments, objects matched the loudness of stimuli with; burst periods that varied over a narrow range (30-50 ms) or a broad range (15.6-500 ms). Burst period and charge were independent over the range of stimulus parameters used; that is, subjects' pitch matches depended only on burst period and were not affected by discriminable differences in charge of ±0.5 dB and ±1.0 dB. Subject' loudness matches depended primarily on charge, were not affected by discriminable differences in burst periods of ±10 ms, and depended only slightly on burst period over the range of 15.6 to 500 ms (2.0 to 64.1 Hz) View full abstract»

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  • A programmable electronic stimulator for FES systems

    Page(s): 234 - 239
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    A low-cost, programmable, galvanically isolated bipolar four channel stimulator for patterned electrical stimulation has been developed. The design is based on a newly developed concept, and it includes a high efficiency DC/DC converter securing high output voltage and sufficient energy to drive four output stages, a microcontroller for control of charge compensation, pulse rate and duration, as well as patterns of exercise and functional use regimes. A user-friendly interface for programming of the stimulator has been developed for the PC host computer, using Windows environment and a push-button control for functional application of the system. The use in humans who suffered a central nervous system lesion and lost voluntary control over muscles necessary for standing, walking, or manipulation was tested. The prototype is small, light, battery-operated, and flexible for various applications View full abstract»

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

    Page(s): 247 - 255
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    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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  • Optical recognition of Braille writing using standard equipment

    Page(s): 207 - 212
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    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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  • Devices for assisting manipulation: a summary of user task priorities

    Page(s): 256 - 265
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    Currently, none of the commercially available rehabilitation robots are widely distributed among individuals with limited use of their arms and hands. Market success requires design that achieves an acceptable tradeoff between function, appearance, ease of use, reliability, and cost. User defined task priorities are an imperative consideration within the design as devices which fail a user's functionality requirement will never succeed in the market place. Consequently, this article reviews nine different task priority surveys conducted by seven institutions across England and North America which reflect the views of over 200 potential users of such technology. They include predevelopment questionnaires that focus on user task ability and anticipated use of an orthosis or rehabilitation robot, and postdevelopment surveys that investigate task functionality with a specific robot. The survey results indicate that a device must accommodate a wide range of object manipulation tasks in a variety of unstructured environments. Specific tasks which rated highly were picking things up from the floor or off a shelf and tasks associated with eating, personal hygiene, and leisure activities. The range of functional tasks implies that interdisciplinary design teams are required for “successful” rehabilitation robotic and orthotic device design View full abstract»

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  • Myoelectric signal characteristics from muscles in residual upper limbs

    Page(s): 266 - 270
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    Myoelectric signal (MES) data were obtained from remnant muscles in residual upper limbs and analogous intact muscles of thirty-two upper-limb deficient subjects. Spectral parameters (mean frequency, median frequency, and equivalent statistical bandwidth) of the MES were calculated and examined for significant differences between the remnant muscle data and intact muscle data. Other factors were examined for possible significant effect on the spectral content of the MES. Although no pattern of spectral difference between the MES of residual versus intact limb muscles was found, spectral differences were apparent by visual inspection in most cases. Level of amputation (above elbow or below elbow) was the sole factor found to have a significant effect on the MES spectral content. Data were separated based on level of amputation; no statistically significant difference between the spectral parameters of residual versus intact muscle MES was found. However, greater variation in the spectral parameters of the remnant muscle data was observed. The results of this study add to one's knowledge of the MES characteristics of remnant muscles, with implications for the design of myoelectric controllers 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