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Neural Systems and Rehabilitation Engineering, IEEE Transactions on

Issue 4 • Date Dec. 2002

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Displaying Results 1 - 12 of 12
  • System for assisted mobility using eye movements based on electrooculography

    Page(s): 209 - 218
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (851 KB)  

    Describes an eye-control method based on electrooculography (EOG) to develop a system for assisted mobility. One of its most important features is its modularity, making it adaptable to the particular needs of each user according to the type and degree of handicap involved. An eye model based on electrooculographic signal is proposed and its validity is studied. Several human-machine interfaces (HMI) based on EOG are commented, focusing our study on guiding and controlling a wheelchair for disabled people, where the control is actually effected by eye movements within the socket. Different techniques and guidance strategies are then shown with comments on the advantages and disadvantages of each one. The system consists of a standard electric wheelchair with an on-board computer, sensors and a graphic user interface run by the computer. On the other hand, this eye-control method can be applied to handle graphical interfaces, where the eye is used as a mouse computer. Results obtained show that this control technique could be useful in multiple applications, such as mobility and communication aid for handicapped persons. View full abstract»

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  • Initial on-line evaluations of the LF-ASD brain-computer interface with able-bodied and spinal-cord subjects using imagined voluntary motor potentials

    Page(s): 219 - 224
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (286 KB)  

    Previous research has focused on developing a brain-controlled switch named the low frequency asynchronous switch design (LF-ASD) that is suitable for intermittent control of devices such as environmental control systems, computers, and neural prostheses. On-line implementations of the LF-ASD have shown promising results in response to actual index finger flexions with able-bodied subjects. This paper reports the results of initial on-line evaluations of the LF-ASD brain-controlled switch with both able-bodied subjects and subjects with high-level spinal-cord injuries. This paper has demonstrated that users can activate the LF-ASD switch by imagining movement. In this paper, two able-bodied subjects were able to control the LF-ASD with imagined voluntary movements with hit (true positive) rates above 70% and false positive rates below 3% while two subjects with high-level spinal-cord injuries demonstrated hit rates ranging from 45-48% and false positive rates below 1%. View full abstract»

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  • Full-screen magnification for windows using DirectX overlays

    Page(s): 225 - 231
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    This paper presents the basic features of software-based magnifiers used by some visually impaired people to read information from a computer screen. The paper briefly presents two major approaches to full-screen magnification for modern multiple window systems (the paper focuses on Microsoft Windows). This paper describes in detail the architecture and operation of a full-screen magnifier that uses Microsoft DirectX Overlays. This approach leads to a robust magnifier that has a low computational overhead. The magnifier has problems with video cards that use a YUV color model but these problems may be addressed by RGB to YUV translation software - an issue that is still to be investigated. The magnifier also has problems when the generic device driver, rather than the manufacturer's device driver, is installed on the system. The paper presents two further strategies for full screen magnification, namely, using multimonitor support and true type fonts for text enlargement. View full abstract»

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  • The instantaneous axis of rotation (IAOR) of the foot and ankle: a self-determining system with implications for rehabilitation medicine application

    Page(s): 232 - 238
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    A noninvasive method for determining the instantaneous axis of rotation (IAOR) of the foot and ankle during human ambulation has been developed. The algorithm uses three-dimensional (3-D) external marker trajectories to describe the IAOR of the calcaneus with respect to the tibia. Multiple optimization techniques were used to fit a plane and a sphere to the marker trajectories, with the constraint that the center of the sphere lies on the plane. The IAOR was defined perpendicular to the plane and passed through the center of the sphere. The results from validation procedures have demonstrated the applicability of the method. Experimental IAOR data acquired from normal adult subjects indicated the ability to track the IAOR during gait. This self-determining system for locating a patient's foot and ankle IAOR during gait may benefit rehabilitation applications in pedorthic and prosthetic design, surgical and nonsurgical treatment, and rehabilitative approaches to suprasegmental functional accommodation. View full abstract»

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  • Paraplegic standing supported by FES-controlled ankle stiffness

    Page(s): 239 - 248
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (630 KB) |  | HTML iconHTML  

    The objective of this paper was to investigate whether a paraplegic subject is able to maintain balance during standing by means of voluntary and reflex activity of the upper body while being supported by closed loop controlled ankle stiffness using FES. The knees and hips of the subject were held in extended positions by a mechanical apparatus, which restricted movement to the sagittal plane. The subject underwent several training sessions where the appropriate level of stiffness around the ankles was maintained by the mechanical apparatus. This enabled the subject to learn how to use the upper body for balancing. After the subject gained adequate skills closed-loop FES was employed to regulate ankle stiffness, replacing the stiffness provided by the apparatus. A method to control antagonist muscle moment was implemented. In subsequent standing sessions, the subject had no difficulties in maintaining balance. When the FES support was withheld, the ability to balance was lost. View full abstract»

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  • Stability analysis for postural control in a two-joint limb system

    Page(s): 249 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (631 KB) |  | HTML iconHTML  

    The stability behavior of a multi-joint limb with electrically activated muscles provides important clues for postural control of motor tasks. The stability property of the musculoskeletal system can be characterized with its eigenvalues evaluated at operating postures in the workspace. A planar arm model with shoulder and elbow joints and three pairs of antagonistic muscles was constructed in ADAMS. Stability behavior of shoulder and elbow joints was analyzed using the loci of eigenvalues in the s-plane. In the analysis of open-loop cocontraction of antagonist muscles with increasing activation from 5% to 100%, the eigenvalues of the shoulder and elbow joints were confined within the left half of the s-plane in a stripe of ±j0.5, and moved toward left onto the real axis. The shoulder eigenvalues were generally nearer to the imaginary axis than the elbow ones, indicating a more oscillatory behavior at the shoulder joint than that at the elbow joint. The effects of joint configuration evaluated within the workspace from 40° to 110° for the elbow and from 40° to 120° for the shoulder showed that the elbow eigenvalues were more prone to configuration changes, particularly elbow angles. We also developed a simulation paradigm for sampled data FES control systems that contain a mixture of continuous time components and sampling and hold effects. This simulation paradigm is useful for realistic simulation of local feedback controller performance. View full abstract»

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  • A review of portable FES-based neural orthoses for the correction of drop foot

    Page(s): 260 - 279
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    Reviews the technological developments in neural orthoses for the correction of upper motor neurone drop foot since 1961, when the technique was first proposed by Liberson and his co-workers. Drop foot stimulator (DFS) developments are reviewed starting with hard-wired single-channel and multichannel surface functional electrical stimulation (FES) systems, followed by implanted drop foot stimulators, and then continuing with microprocessor-based surface and implanted drop foot stimulators. The review examines the role of artificial and "natural" sensors as replacements for the foot-switch as the primary control sensor in drop foot stimulators. DFS systems incorporating real-time control of FES and completely implanted DFS systems finish the review. View full abstract»

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  • The effects of long-term FES-assisted walking on intrinsic and reflex dynamic stiffness in spastic spinal-cord-injured subjects

    Page(s): 280 - 289
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (622 KB) |  | HTML iconHTML  

    The effects of long-term functional electrical stimulation (FES)-assisted walking on ankle dynamic stiffness were examined in spinal cord-injured (SCI) subjects with incomplete motor function loss. A parallel-cascade system identification method was used to identify intrinsic and reflex contributions to dynamic ankle stiffness at different ankle positions while subjects remained relaxed. Intrinsic stiffness dynamics were well modeled by a linear second-order model relating intrinsic torque to joint position. Reflex stiffness dynamics were accurately described by a linear third-order model relating halfwave rectified velocity to reflex torque. We examined four SCI subjects before and after long-term FES-assisted walking (>16 mo). Another SCI subject, who used FES for only five months was examined 12 mo latter to serve as a non-FES, SCI control. Reflex stiffness decreased in FES subjects by an average of 53% following FES-assisted walking, intrinsic stiffness also dropped by 45%. In contrast, both reflex and intrinsic stiffness increased in the non-FES, SCI control. These findings suggest that FES-assisted walking may have therapeutic effects, helping to reduce abnormal joint stiffness. View full abstract»

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  • Classification of finger activation for use in a robotic prosthesis arm

    Page(s): 290 - 293
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB)  

    Hand amputees would highly benefit from a robotic prosthesis, which would allow the movement of a number of fingers. In this paper we propose using the electromyographic signals recorded by two pairs of electrodes placed over the arm for operating such prosthesis. Multiple features from these signals are extracted whence the most relevant features are selected by a genetic algorithm as inputs for a simple classifier. This method results in a probability of error of less than 2%. View full abstract»

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  • Functionally selective peripheral nerve stimulation with a flat interface nerve electrode

    Page(s): 294 - 303
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB)  

    One of the important goals of peripheral nerve electrode development is to design an electrode for selective recruitment of the different functions of a common nerve trunk. A challenging task is gaining selective access to central axon populations. In this paper, a simple electrode that takes advantage of the neural plasticity to reshape the nerve is presented. The flat interface nerve electrode (FINE) reshapes the nerve into a flat geometry to increase the surface area and move central axon populations close to the surface. The electrode was implanted acutely on the sciatic nerve of eight cats. The FINE can significantly reshape the nerve and fascicles (p<0.0001) while maintaining the same total nerve cross-sectional area. The stimulation thresholds were 2.89 nC for pulse amplitude modulation and 10.2 nC for pulsewidth modulation. Monopolar, square-pulse stimulation with single contacts on the FINE selectively recruited each of the four main branches of the sciatic nerve. Simultaneous stimulation with two contacts produced moments about the ankle joint that were a combination of the moments produced by the individual contacts when stimulated separately. View full abstract»

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  • Author index

    Page(s): 304 - 305
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    Freely Available from IEEE
  • Subject index

    Page(s): 305 - 309
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    Freely Available from IEEE

Aims & Scope

IEEE Transactions on Neural Systems and Rehabilitation Engineering focuses on the rehabilitative and neural aspects of biomedical engineering.

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Editor-in-Chief
Paul Sajda
Columbia University