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Rehabilitation Engineering, IEEE Transactions on

Issue 1 • Date Mar 1998

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Displaying Results 1 - 13 of 13
  • A PC-based Braille library system for the sightless

    Page(s): 60 - 65
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    This paper presents a novel multiclient braille reading system developed around a single low cost personal computer. The system primarily addresses the needs of the Braille libraries, where different texts are needed to be read by different users simultaneously. Moreover, the system can simultaneously cater to different texts written in different languages. This feature makes it specially suitable for use by multilingual nationalities. The major advantage of this system is its low cost, compared to the other systems available and is specially attractive for the developing or underdeveloped countries. The paper describes the system, first from the user point of view and then presents the hardware and software design details. The system performance has been evaluated by the sightless users and has shown encouraging results View full abstract»

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  • An elbow extension neuroprosthesis for individuals with tetraplegia

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    Functional electrical stimulation (FES) of the triceps to restore control of elbow extension was integrated into a portable hand grasp neuroprosthesis for use by people with cervical level spinal cord injury. An accelerometer mounted on the upper arm activated triceps stimulation when the arm was raised above a predetermined threshold angle. Elbow posture was controlled by the subjects voluntarily flexing to counteract the stimulated elbow extension. The elbow moments created by the stimulated triceps were at least 4 N·m, which was sufficient to extend the arm against gravity. Electrical stimulation of the triceps increased the range of locations and orientations in the workspace over which subjects could grasp and move objects. In addition, object acquisition speed was increased. Thus elbow extension enhances a person's ability to grasp and manipulate objects in an unstructured environment View full abstract»

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  • An electromechanical testing device for assessment of hand motor function

    Page(s): 88 - 94
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    Instrumentation was designed and constructed to assess the strength and function of the intrinsic muscles of the index and long fingers of the hand. The device consisted of two beams instrumented with strain gages, signal conditioners, and a microprocessor-based embedded controller. A study conducted on four weak spinal cord injury (SCI), three nonweak SCI, and 21 control subjects demonstrated a trend of reduced maximum pinching force between the index and long fingers in weak SCI subjects compared with the other two groups. Weak SCI subjects also demonstrated a significantly slower rapid alternating movement speed of the index finger compared with the other two groups. The instrument has potential use as a clinical tool for quantitative evaluation of the progression of hand motor dysfunction View full abstract»

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  • EEG-based communication and control: short-term role of feedback

    Page(s): 7 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    When people learn to control the amplitudes of certain electroencephalogram (EEG) components (e.g., the 8-12 Hz μ-rhythm over sensorimotor cortex) and use them to move a cursor to a target on a video screen, feedback about performance is normally provided by cursor movement and by trial outcome (i.e., success or failure). The authors assessed the short-term effects of this feedback on EEG control. After subjects received initial training with feedback present, feedback was removed intermittently for periods of several minutes. Subjects still displayed EEG control when feedback was removed. Removal of cursor movement alone appeared to have effects comparable to removal of both cursor movement and trial outcome. These results show that, in the short-term at least, μ-rhythm control is not dependent on the sensory input provided by cursor movement. They also suggest that feedback can have inhibitory as well as facilitatory effects on EEG control, and that these effects vary across subjects. This finding has implications for the design of training procedures View full abstract»

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  • Multidimensional electrocutaneous stimulation

    Page(s): 95 - 101
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    Probing the subjective response to a five-parameter electrocutaneous stimulus has revealed a noisy perceptual space. A method for reducing the noise is hypothesized and experimentally tested by comparing the intensity discrimination thresholds along and off the energy gradient. Preliminary results show a reduction of the threshold of up to 60% when stimulating along the gradient. The method is exploited to implement an optimal intensity control in an electrotactile vision-substitution device View full abstract»

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  • A rate-controlled indentor for in vivo analysis of residual limb tissues

    Page(s): 12 - 20
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    A tissue tester was designed to enable rate-controlled indentation of the bulk soft tissues of lower extremity residual limbs. The tissue tester employs a digital linear actuator that implements rate-controlled indentation, and a load cell that measures the reaction force resulting from tissue indentation. Viscoelastic phenomena such as preconditioning, hysteresis and force relaxation can be assessed, and the effect of varying indentation rates on soft tissue stiffness can be investigated. The device accommodates indentor excursions up to 30 mm, indentation at rates of 0 to 10 mm/s, reaction forces up to 44 N, and multiple loading/unloading cycles. The tissue tester is controlled via a notebook personal computer with a PCMCIA data acquisition card. The tissue testing trials are automated and the entire test system is portable and amenable for use in a clinical or research environment. System output consists of force-displacement curves from cyclic loading, and force-time curves following ramped-step indentation. The mean indentor positioning error was 0.071 (±0.75)% of the desired displacement. This error varied as a function of indentation and was approximately independent of the indentation rate. Indentation rates were accurate to within 0.94(±0.68)% of the desired value and also varied with indentation. Indentation of a viscoelastic foam yielded force-displacement curves that were consistent with that obtained from an Instron universal testing machine View full abstract»

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  • Design of a miniaturized ultrasonic bladder volume monitor and subsequent preliminary evaluation on 41 enuretic patients

    Page(s): 66 - 74
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    Nocturnal incontinence (enuresis) affects 20% of children over four years old, and this figure typically decreases by 15% each year. At the age of 18, 1% of those people remain enuretic. Nocturnal enuresis can be treated by means of a conditioning device that awakens the patient once the urine level has reached a preestablished threshold of the capacity of his or her bladder. The authors have designed and implemented a portable miniaturized ultrasonic monitor, which permits estimation of the urine volume with an accuracy of 75%. Prototypes have been completed and validated on 41 patients (children) at Ste. Justine Hospital (Montreal). On the first group of 33 patients, the authors used a hand-held transducer to determine the volume detection range, which is accurate for volumes between 40 and 400 mL. With the second group of 8 patients, the device was mounted on an elastic belt around the abdomen. Measurements were taken in order to validate the accuracy of urine threshold detection and the activation of the corresponding alarm View full abstract»

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  • Issues in impedance selection and input devices for multijoint powered orthotics

    Page(s): 102 - 105
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    The authors investigated the applicability of impedance controllers to robotic orthoses for arm movements. They had tetraplegics turn a crank using their paralyzed arm propelled by a planar robot manipulandum. The robot was under impedance control, and chin motion served as command source. Stiffness varied between 50, 100, or 200 N/m and damping varied between 5 or 15 N/m/s. Results indicated that a low stiffness and high viscosity provided better directional control of the tangential force exerted on the crank View full abstract»

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  • Effects of alignment changes on stance phase pressures and shear stresses on transtibial amputees: measurements from 13 transducer sites

    Page(s): 21 - 31
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    Interface pressures and shear stresses were measured at 13 sites on two unilateral below-knee amputee subjects ambulating with lower-limb patellar-tendon-bearing prostheses. Interface stresses at the time of the first peak in the shank axial force-time curve were investigated at different socket-shank alignment settings. Stress magnitudes ranged from 1.2 to 214.7 kPa for pressure and 0.4 to 79.6 kPa for resultant shear stress, and changes in stress due to misalignment ranged from 1.3 to 80.7 kPa for pressure and from 0.2 to 38.0 kPa for resultant shear stress. For both subjects interface stress changes were much greater in the anterior socket region than in the lateral or posterior regions. Thus, alignment changes had a localized effect on interface stresses. Plots of alignment versus pressure or resultant shear stress were nonlinear for both subjects, in a number of cases maximizing or minimizing at the nominal alignment, indicating complex interface stress-alignment relationships. Variation (standard deviation/mean) was not significantly different for nominal versus misaligned steps, indicating that the subjects adapted well to the alignment changes. Session to session differences in interface stresses were typically larger than interface stress differences induced by alignment modifications. Thus, while these subjects compensated well for alignment changes to maintain consistent interface stresses within a session, they did not do so for different sessions conducted weeks apart View full abstract»

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  • A programmable sound processor for advanced hearing aid research

    Page(s): 53 - 59
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    A portable sound processor has been developed to facilitate research on advanced hearing aids. Because it is based on a digital signal processing integrated circuit (Motorola DSP56001), it can readily be programmed to execute novel algorithms. Furthermore, the parameters of these algorithms can be adjusted quickly and easily to suit the specific hearing characteristics of users. In the processor, microphone signals are digitized to a precision of 12 bits at a sampling rate of approximately 12 kHz for input to the DSP device. Subsequently, processed samples are delivered to the earphone by a novel, fully-digital class-D driver. This driver provides the advantages of a conventional class-D amplifier (high maximum output, low power consumption, low distortion) without some of the disadvantages (such as the need for precise analog circuitry). In addition, a cochlear implant driver is provided so that the processor is suitable for hearing-impaired people who use an implant and an acoustic hearing aid together. To reduce the computational demands on the DSP device, and therefore the power consumption, a running spectral analysis of incoming signals is provided by a custom-designed switched-capacitor integrated circuit incorporating 20 bandpass filters. The complete processor is pocket-sized and powered by batteries. An example is described of its use in providing frequency-shaped amplification for aid users with severe hearing impairment. Speech perception tests confirmed that the processor performed significantly better than the subjects' own hearing aids, probably because the digital filter provided a frequency response generally closer to the optimum for each user than the simpler analog aids View full abstract»

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  • Robot-aided neurorehabilitation

    Page(s): 75 - 87
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    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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  • Stepping over obstacles during locomotion: insights from multiobjective optimization on set of input parameters

    Page(s): 43 - 52
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    In this study the authors investigate possible objectives that the central nervous system (CNS) may consider in planning a strategy for stepping over an obstacle. A link segment simulation model has been developed based on Lagrangian dynamics, with which muscle force inputs can be optimized to best satisfy the postulated objectives for landing stability, obstacle clearance, and efficiency of the movement. A direct optimization approach with multiobjective criteria based on the kinematic and kinetic characteristics of the swing phase of locomotion is used in the simulation. The role of initial conditions at toe-off and biarticular muscle forces during the swing phase was also investigated. The optimization was performed for both leading limb and the trailing limb during the swing phase. The simulation results demonstrate that the use of biarticular muscles is sufficient to clear a range of obstacles with the trailing limb (obstacle encountered during early swing). Stride length or landing stability objectives need not be specified suggesting a simpler control of trailing limb trajectory by the CNS (one of stride length or landing stability objectives were not necessary). In contrast while the use of biarticular muscles can be sufficient to clear obstacles with the leading limb (obstacle encountered during mid to late swing), a stable landing and smooth toe and knee trajectories are compromised without suitable initial conditions at toe-off. The results suggest that the set of postulated objectives for the lead limb is adequate, although not complete View full abstract»

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  • Control of stance during lateral and anterior/posterior surface translations

    Page(s): 32 - 42
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    The purpose of this study was to compare and contrast postural responses to lateral and A/P surface translations by quantifying joint positions, bilateral three-dimensional (3-D) ground reaction forces, and lower limb and trunk muscle electromyographic (EMG) activity. Subjects stood on a movable platform which was randomly translated in four different directions. The kinematic patterns in response to lateral and anterior/posterior (A/P) surface translations were similar in that there was a sequential displacement and reversal of the shank/thigh and then trunk segments. While the body center of mass (CoM) was displaced equally in response to lateral and A/P translations, equilibrium was maintained by redistributing the vertical forces and changing the shear forces exerted against the support surface. These force responses were bilaterally symmetrical for AIP translations but not for lateral translations. With respect to EMG activity, the first muscle activated was the proximal tensor fascia latae for lateral translations whereas the distal muscles were recruited first for A/P translations. Results from this study suggest that control of postural equilibrium may be similar for A/P and lateral translations, although specific differences in patterns may reflect various biomechanical constraints of the trunk and the lower extremities associated with the two planes of movement 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