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Rehabilitation Engineering, IEEE Transactions on

Issue 2 • Date Jun 1999

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Displaying Results 1 - 16 of 16
  • Computer simulation and sled test validation of a powerbase wheelchair and occupant subjected to frontal crash conditions

    Publication Year: 1999 , Page(s): 234 - 244
    Cited by:  Papers (11)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The Americans with Disabilities Act (ADA) has led to an increased number of wheelchair users seeking transportation services. Many of these individuals are unable to transfer to a vehicle and are instead required to travel seated in their wheelchairs. Unfortunately, wheelchairs are not typically designed with the same occupant protection features as motor vehicle seats, and wheelchair seated occupants may be at higher risk for injury in a crash. To study the effects of crash level forces on wheelchairs and their occupants, it is useful to simulate crash conditions using computer modeling. This study has used a dynamic lumped mass crash simulator, in combination with sled impact testing, to develop a model of a secured commercial powerbase and restrained occupant subjected to a 20 g/30 mph frontal motor vehicle crash. Time histories profiles of simulation-generated wheelchair kinematics, occupant accelerations, tiedown forces and occupant restraint forces were compared to sled impact testing for model validation. Validation efforts for this model were compared to validation results found acceptable for the ISO/SAE surrogate wheelchair model. This wheelchair-occupant simulation model can be used to investigate wheelchair crash response or to evaluate the influence of various factors on occupant crash safety View full abstract»

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  • System identification of tendon reflex dynamics

    Publication Year: 1999 , Page(s): 193 - 203
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    Patellar tendon reflexes were evaluated in 12 healthy adult subjects using several measures of the reflex responses and of the system input-output relationship. A hand-held instrumented hammer was used to tap the patellar tendon and to elicit the reflex response. Tendon reflex dynamics were estimated using the recorded tapping force (as input) and the quadriceps muscle electromyogram and knee joint extension torque signals (as output). A dome shaped rubber pad was mounted onto the most sensitive spot on the patellar tendon, where it served as a tapping target, and helped to reduce the reflex variability significantly (p<0.01). The input-output properties of the system relating the reflex torque to the tapping force were characterized using several measures: the tendon reflex gain (Gtr), contraction rate (Rc), and half-relaxation rate (Rhr). Reflex loop delay (td) was estimated using the delay from the onset of tapping force to the onset of reflex torque. We determined that these system parameters provided significantly more repeatable and consistent characterization of tendon reflexes than did reflexive torque or EMG signals alone (p<0.025). The input-output relationship relating the EMG signals of the stretched muscle to the tapping force was also identified to help characterize neuromuscular dynamics of tendon reflexes. The observed sensitivity and consistency of the reflex system measures suggest that with appropriate simplification of the instrumentation, these methods may prove useful in routine clinical practice, and may allow more precise quantification of the tendon jerk than is currently feasible with standard clinical tests View full abstract»

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  • Neurofuzzy adaptive controlling of selective stimulation for FES: a case study

    Publication Year: 1999 , Page(s): 183 - 192
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    A controller was designed for the selective stimulation of the sciatic nerve with a multiple contact cuff electrode to generate a desired torque in the ankle joint of cat. The design integrates three approaches, artificial neural network (ANN) modeling, fuzzy logical adaptation, and geometrical mapping. The geometrical mapping refers to the vector transformation from the joint coordinates to the virtual muscle coordinates which have been conceptually developed to represent the major recruitment features of contact-based functional units in the physical plant. This method reduces the complexity of generating a data set for training the neural network in the feedforward path and implementing the on-line learning algorithm embedded in the feedback loop. The controller was evaluated by computer simulation with the experimental data obtained from the torque generation in five acute cats. The results show that the ANN-based feedforward is capable of predicting 65% of a given desired isometric torque, and the fuzzy logical machine is able to provide suitable gains for feedback modulation to reduce the error from 35 to 8.5% and produce a robust control View full abstract»

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  • Control of FES thumb force using slip information obtained from the cutaneous electroneurogram in quadriplegic man

    Publication Year: 1999 , Page(s): 215 - 227
    Cited by:  Papers (46)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    A tetraplegic volunteer was implanted with percutaneous intramuscular electrodes in hand and forearm muscles. Furthermore, a sensory nerve cuff electrode was implanted on the volar digital nerve to the radial side of the index finger branching off the median nerve. In laboratory experiments a stimulation system was used to produce a lateral grasp (key grip) while the neural activity was recorded with the cuff electrode. The nerve signal contained information that could be used to detect the occurrence of slips and further to increase stimulation intensity to the thumb flexor/adductor muscles to stop the slip. Thereby the system provided a grasp that could catch an object if it started to slip due to, for example, decreasing muscle force or changes in load forces tangential to the surface of the object. This method enabled an automatic adjustment of the stimulation intensity to the lowest possible level without loosing the grip and without any prior knowledge about the strength of the muscles and the weight and surface texture of the object View full abstract»

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  • A biomimetic controller for a multifinger prosthesis

    Publication Year: 1999 , Page(s): 121 - 129
    Cited by:  Papers (19)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    A novel controller for a multifinger hand prosthesis was developed and tested to measure its accuracy and performance in transducing volitional signals for individual “phantom” fingers. Pneumatic sensors were fabricated from open-cell polymeric foam, and were interposed between the prosthetic socket and superficial extrinsic tendons associated with individual finger flexion. Test subjects were prompted to move individual fingers or combinations thereof to execute either taps or grasps. Sensor outputs were processed by a computer that controlled motions of individual fingers on a mechanical prosthesis. Trials on three upper-limb amputees showed that after brief training sessions, the TAP controller was effective at producing voluntary flexions of individual fingers and grasping motions. Signal energies were between 5 and 25 dB relative to noise from all sources, including adjacent sensors, indicating high degrees of both sensitivity and specificity for tendon-associated transduction. Finger flexions at up to three repetitions per second, and rhythmic tapping of sequential fingers were readily transduced. One amputee subject was able to play a short piano piece with three fingers, at approximately one-quarter normal tempo. TAP sensors responded linearly to graded forces from individual fingers, indicating proportional force control. The authors' results demonstrate the feasibility of restoring some degree of finger dexterity by noninvasive sensing of extrinsic tendons View full abstract»

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  • Robotic assistance of an active upper limb exercise in neurologically impaired patients

    Publication Year: 1999 , Page(s): 254 - 256
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    The principle of using robotic techniques to assist an active upper limb exercise is demonstrated in ten patients with weakness and spasticity. Using a servo motor to apply torque about the elbow, the mean range of active extension-flexion was increased in every patient. Sample kinematic and electromyographic (EMG) data are given View full abstract»

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  • Optimization and application of a wrap-spring clutch to a dynamic knee-ankle-foot orthosis

    Publication Year: 1999 , Page(s): 130 - 134
    Cited by:  Papers (16)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    A dynamic knee-brace system (DKBS) has been designed which provides stance phase stability and swing phase freedom. A wrap-spring clutch controls knee flexion. Clutch optimization was performed minimizing clutch length. Kinematic tests on a normal subject using the DKBS document nearly normal dynamic knee flexion during swing (380 versus 530 for normal) View full abstract»

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  • The effects of epimysial electrode location on phrenic nerve recruitment and the relation between tidal volume and interpulse interval

    Publication Year: 1999 , Page(s): 150 - 158
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    Electrode location is of vital importance to diaphragm pacing devices using electrodes implanted on the diaphragm. Complete phrenic nerve recruitment with a single epimysial electrode implanted on the abdominal surface of the diaphragm required placement within 1 cm of the motor point. Recruitment could be increased further using multiple electrodes, provided the electrodes were implanted on opposite sides of the phrenic nerve motor point. The location of the implanted electrode relative to the phrenic nerve motor point also affected the relation between the stimulus interpulse interval (IPI) and the measured tidal volume. Specifically, the authors found that electrodes implanted lateral to the phrenic nerve motor point had different tidal volume-IPI relations than electrodes placed anterior or posterior to the motor point. The authors concluded that properly placed epimysial electrodes are required to obtain adequate phrenic nerve recruitment for full time ventilation and knowledge of the relative location of the electrode with respect to motor point is necessary to predict the tidal volume produced by a specific IPI View full abstract»

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  • Adaptive noncontact gesture-based system for augmentative communication

    Publication Year: 1999 , Page(s): 174 - 182
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    An adaptive noncontact gesture-based system for augmentative communication is described. The system detects movement of any anatomical site through the analysis of reflected speckle. This movement is converted into two-dimensional (2-D) cursor coordinates and an adaptive software interface provides click actions and decision strategies. The system requires no accessory to be placed on the user. The system was developed in conjunction with user groups, who participated in the evaluation of the system. The usability results obtained illustrate the utility of the system. The system also compared favorably with other interface solutions View full abstract»

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  • A new strategy for controlling the level of activation in artificially stimulated muscle

    Publication Year: 1999 , Page(s): 167 - 173
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    Distributed stimulation of slow skeletal muscle has previously been used to produce smooth tetanic contractions at low stimulus rates. This involved distributed or interleaved stimulation of portions of the muscle with near equal tension contributions. Extending this to fast and mixed muscle encounters difficulties in getting and maintaining equal twitch responses for the portions. This need has now been circumvented by using distributed stimulation with unequal interpulse intervals. Described here is a microprocessor-based eight channel distributed muscle stimulator that can adjust stimulation timing to produce an optimally smooth tension over a range of stimulus rates even when the portions are unequal. This design is based on modeling results. Distributed stimulation experiments performed on skeletal muscle show that this method can be used to achieve smooth tension at physiological stimulus rates, which should reduce fatigue. This has important implications in functional neuromuscular stimulation (FNS) as well as in enabling experiments to be conducted to characterize the biomechanical behavior of partially activated fast and mixed muscle View full abstract»

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  • Electronic design of a multichannel programmable implant for neuromuscular electrical stimulation

    Publication Year: 1999 , Page(s): 204 - 214
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    An advanced stimulator for neuromuscular stimulation of spinal cord injured patients has been developed. The stimulator is externally controlled and powered by a single encoded radio frequency carrier and has four independently controlled bipolar stimulation channels. It offers a wide range of reprogrammability and flexibility, and can be used in many neuromuscular electrical stimulation applications. The implant system is adaptable to patient's needs and to future developments in stimulation algorithms by reprogramming the stimulator. The stimulator is capable of generating a wide range of stimulation waveforms and stimulation patterns and therefore is very suitable for selective nerve stimulation techniques. The reliability of the implant has been increased by using a forward error detection and correction communication protocol and by designing the chip for structural testability based on scan test approach. Implemented testability scheme makes it possible to verify the complete functionality of the implant before and after implantation. The stimulators architecture is designed to be modular and therefore its different blocks can be reused as standard building blocks in the design and implementation of other neuromuscular prostheses. Design for low-power techniques have also been employed to reduce power consumption of the electronic circuitry View full abstract»

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  • Evaluation of a suture electrode for direct bladder stimulation in a lower motor neuron lesioned animal model

    Publication Year: 1999 , Page(s): 159 - 166
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The purpose of this study was to evaluate a “suture” type electrode for direct bladder stimulation in an animal model of a lower motor neuron lesion. During an initial surgery, 5 male cats were instrumented under anesthesia using multistranded, 316 LVM, stainless-steel, wire electrodes implanted on the bladder wall serosa above the trigone area. Electrodes were constructed with a needle attached to the end that was removed after suturing the electrode in place. Additional instrumentation included urinary bladder catheters (tubes) for pressure recording and filling, and hook type electrodes for leg and pelvic floor electromyography recording. Chronic bladder filling and stimulation studies were conducted in tethered animals 3 to 4 weeks following surgery. To test these electrodes in a spinal cord injury model, a lower motor neuron lesion was performed including the sacral cord and complete nerve roots at L6 and below. These animals were evaluated during weeks 3 and 10 after injury. Direct bladder stimulation induced active contractions and voiding both before and after spinal cord injury. Effective stimulation parameters consisted of 40 pulses per s, 300 μs to 1 ms pulse duration, a stimulation period from 3 to 4 s, and a stimulation current from 10 to 40 mA. Fluoroscopy revealed an open membranous urethra during stimulation and following stimulation. A small diameter penile urethra was observed to limit flow. Postmortem evaluation of the suture electrode revealed no abnormalities such as corrosion, migration into the bladder lumen or displacement. These findings indicate that suture electrodes are suitable and effective for short-term implantation in the lower motor neuron animal model View full abstract»

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  • Automatic control design for a dynamic knee-brace system

    Publication Year: 1999 , Page(s): 135 - 139
    Cited by:  Papers (4)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    A self-contained electronically controlled dynamic knee-brace system (DKBS) has been designed and tested which allows knee flexion during swing phase, but restricts flexion during the stance phase of gait. Cardiovascular energy measurements indicate that DRBS use allowed a more energy efficient gait View full abstract»

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  • An audio- and speech-based interface for computer-controlled scientific instruments

    Publication Year: 1999 , Page(s): 245 - 253
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    Laboratory instruments are intrinsic to research and work in a wide array of scientific fields. They are used for the control of devices, data storage, and data analysis. The control of instruments is increasingly changing from independent on-instrument controls to multiple instrument integrated software control. Unfortunately, the graphical representation of controls and data makes it difficult for an individual with a visual impairment to independently operate laboratory instruments. Alternative interfaces have been previously developed for these individuals but have often proved limited in scope and accuracy, or otherwise expensive. The resulting inaccessibility to affordable and accurate scientific instrumentation, unfortunately, discourages many individuals with a visual impairment from entering scientific fields of research or work. This paper introduces an alternative interface method developed for LabVIEW, National Instruments' instrumentation software package. The method is specifically designed for individuals with visual impairments, and uses alternative navigation techniques as well as audio feedback. The developed user interface uses simple keyboard inputs to traverse through a hierarchical tree-based menu system. Speech and audio tones are used to alert the user to system settings and errors, as well as a help mechanism and data analysis tool. At this time, alternative interfaces have been developed for the following basic laboratory instruments: an oscilloscope and function/arbitrary waveform generator. The interface methodology, however, can be extended to include any scientific instrument that can be controlled by LabVIEW View full abstract»

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  • Myoelectric activation pattern during gait in total knee replacement: relationship with kinematics, kinetics, and clinical outcome

    Publication Year: 1999 , Page(s): 140 - 149
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    Gait usually presents an excellent improvement after total knee replacement. Nevertheless, some abnormalities persist even after a long period of time. The abnormal knee patterns have been attributed to several possible causes, such as implant geometry and surgical technique, posterior cruciate ligament sparing/sacrificing, preoperative “stiff-knee” pattern due to pain and altered biomechanics, weakness of the extensor muscles, preoperative arthritic pattern, proprioceptive deficiency, and multijoint degenerative involvement. Cocontraction of the knee flexors and extensors is a common strategy adopted to reduce strain and shear forces at the joint, but it increases compressive forces and joint loading. Even in patients with an excellent functional score, the duration of the implant may be compromised by an altered neuromuscular control of the knee. Here, the authors report a single case study carried out over two years on a patient that underwent total knee replacement. The aim of this work is to show that quantitative gait analysis is essential to augment the understanding of the mechanisms underlying gait, thus enabling clinicians to adapt the rehabilitation program to the specific patient. Although the limits of single case reports are obvious, the authors believe that this evaluation methodology could be beneficial for assessing the effectiveness of rehabilitation programs aimed at achieving an active control of the knee during gait through a correct muscular activation pattern View full abstract»

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  • A simple radiographic measurement method for polyethylene wear in total knee arthroplasty

    Publication Year: 1999 , Page(s): 228 - 233
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    This study describes a new method for evaluating polyethylene wear in total knee arthroplasty. Since the amount of wear is dependent on a number of variables such as the weight and activity of the patient, it should be estimated based on in vivo measurements. We used a computer vision technique called three-dimensional/two-dimensional (3-D/2-D) matching to perform in vivo assessment using a single-plane radiograph. Using the 3-D/2D matching algorithm we estimated the 3-D position and orientation of each knee implant and then measured the femorotibial distance, which is defined as the shortest perpendicular distance from the tibial tray to the femoral component. The accuracy of the proposed 3-D/2-D matching method was determined by in vitro investigations. The worst errors in in-plane/out-of-plane translations and rotations were 0.20/1.95 mm and 0.17/0.29°, respectively. The root-mean-square error in femorotibial distance measurements using real polyethylene inserts was 0.04 mm. Results of in vivo femorotibial distance measurements are also described 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