scholarly journals A Functional Electrical Stimulator to Enable Grasping Through Wrist Flexion

2022 ◽  
Vol 16 ◽  
pp. 19-29
Author(s):  
S. J. Mahendra ◽  
Viswanath Talasila ◽  
Abhilash G. Dutt ◽  
Mukund Balaji ◽  
Abhishek C. Mouli
Keyword(s):  
Current Source ◽  
Angular Position ◽  
Wrist Flexion ◽  
Electrical Discharges ◽  
Stimulation Parameters ◽  
Movement Artifact ◽  
Angular Data ◽  
Electrical Loads ◽  
Electrical Stimulator ◽  
Functional Movements

Functional electrical stimulation is an assistive technique that utilizes electrical discharges to produce functional movements in patients suffering from neurological impairments. In this work, a biphasic, programmable current- controlled functional electrical stimulator system is designed to enable hand grasping facilitated by wrist flexion. The developed system utilizes an operational amplifier based current source and is supported by a user interface to adjust stimulation parameters. The device is integrated with an accelerometer to measure the degree of stimulated movement. The system is validated, firstly, on two passive electrical loads and subsequently on four healthy volunteers. The device is designed to deliver currents between 0-30mA, and the error between the measured current and simulated current for two loads were -0.967±0.676mA and -0.995±0.97mA. The angular data from the accelerometer provided information regarding variations in movement between the subjects. The architecture of the proposed system is such that it can, in principle, automatically adjust the parameters of simulation to induce the desired movement optimally by measuring a stimulated movement artifact (e.g., angular position) in real time.

scholarly journals A Wiener Model Based Closed Loop FES for Positional Control During Wrist Flexion

2021 ◽  
Vol 15 ◽  
pp. 829-835
Author(s):  
S. J., Mahendra ◽  
Vishwanath Talasila ◽  
Abhilash G. Dutt
Keyword(s):  
Healthy Volunteers ◽  
Closed Loop ◽  
Angular Position ◽  
Open Loop ◽  
Wiener Model ◽  
Wrist Flexion ◽  
Pulse Width Modulated ◽  
Nonlinear Pid Controller ◽  
Functional Movements ◽  
Positional Control

Functional electrical stimulation is an assistive technique used to produce functional movements in patients suffering from neurological impairments. However, existing open-loop clinical FES systems are not adequately equipped to compensate for the nonlinear, time-varying behaviour of the muscles. On the other hand, closed-loop FES systems can compensate for the aforementioned effects by regulating the stimulation to induce desired contractions. Therefore, this work aims to present an approach to implement a closed-loop FES system to enable angular positional control during wrist flexion. First, a Wiener model describing the response of the wrist flexor to pulse width modulated stimulation was identified for two healthy volunteers. Second, a nonlinear PID controller (subject-specific) was designed based on the identified models to enable angular positional control during wrist flexion. Subsequently, the controller was implemented in real-time and was tested against two reference angles on healthy volunteers. This study shows promise that the presented closed-loop FES approach can be implemented to control the angular position during wrist flexion or a novelty of the work when compared with the existing work.

scholarly journals iHandU: A Novel Quantitative Wrist Rigidity Evaluation Device for Deep Brain Stimulation Surgery

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 331 ◽  
Author(s):  
Elodie Múrias Lopes ◽  
Maria do Carmo Vilas-Boas ◽  
Duarte Dias ◽  
Maria José Rosas ◽  
Rui Vaz ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Lessons Learned ◽  
Wrist Flexion ◽  
Stimulation Parameters ◽  
Average Accuracy ◽  
Gyroscope Sensor ◽  
Work Done ◽  
Deep Brain Stimulation Surgery ◽  
Deep Brain

Deep brain stimulation (DBS) surgery is the gold standard therapeutic intervention in Parkinson’s disease (PD) with motor complications, notwithstanding drug therapy. In the intraoperative evaluation of DBS’s efficacy, neurologists impose a passive wrist flexion movement and qualitatively describe the perceived decrease in rigidity under different stimulation parameters and electrode positions. To tackle this subjectivity, we designed a wearable device to quantitatively evaluate the wrist rigidity changes during the neurosurgery procedure, supporting physicians in decision-making when setting the stimulation parameters and reducing surgery time. This system comprises a gyroscope sensor embedded in a textile band for patient’s hand, communicating to a smartphone via Bluetooth and has been evaluated on three datasets, showing an average accuracy of 80%. In this work, we present a system that has seen four iterations since 2015, improving on accuracy, usability and reliability. We aim to review the work done so far, outlining the iHandU system evolution, as well as the main challenges, lessons learned, and future steps to improve it. We also introduce the last version (iHandU 4.0), currently used in DBS surgeries at São João Hospital in Portugal.

Validation of a Frequency Weighted Filter for Repetitive Wrist Flexion Tasks against a Load

1996 ◽  
Vol 40 (13) ◽  
pp. 717-721
Author(s):  
Mei-Li Lin ◽  
Robert G. Radwin
Keyword(s):  
Regression Analysis ◽  
Linear Regression Analysis ◽  
Stress Exposure ◽  
Wrist Flexion ◽  
Analog Scale ◽  
Experimental Conditions ◽  
Biomechanical Stress ◽  
Angular Data ◽  
Subjective Discomfort ◽  
Industrial Task

This experiment validates an instrument that implements a force and frequency weighted filter for biomechanical stress exposure assessment. This filter network was developed based on a previously established discomfort model that associated physical stress of force, posture and repetition with subjective discomfort. A simulated industrial task was used in the current study to test the instrument involving repetitively transferring a peg and inserting it into a hole against a controlled resistance. Ten subject performed the task for six conditions. Continuous wrist angular data were recorded using an electrogoniometer and processed through the filter. Subjective discomfort was reported after performing the task for one hour using a 10 cm visual analog scale. The discomfort model was shown to estimate relative discomfort for the experimental conditions tested ( r2 = 0.98, p < .05). Linear regression analysis showed that the instrument aptly predicted subjective discomfort ( r2 = 0.87, p < .05). Applications and limitations of this instrument are explored.

scholarly journals Classification of the Angular Position During Wrist Flexion-extension Based on EMG Signals

2021 ◽  
Vol 25 ◽  
Author(s):  
María Alexandra Fajardo-Perdomo ◽  
Verónica Guardo-Gómez ◽  
Alvaro David Orjuela-Cañón ◽  
Andrés Felipe Ruiz-Olaya
Keyword(s):  
Pattern Recognition ◽  
Wrist Joint ◽  
Angular Position ◽  
Recognition Algorithm ◽  
Ar Model ◽  
Model Parameters ◽  
Wrist Flexion ◽  
Pattern Recognition Algorithm ◽  
Time Frequency ◽  
Flexion Extension

Objective: To evaluate a group of features in a myoelectric pattern recognition algorithm to differentiate between five angular positions of the wrist during flexion-extension movements. Materials and Methods: An experimental configuration was made to capture the EMG and wrist joint angle related to flexion-extension movements. After that, a myoelectric pattern recognition algorithm based on a multilayer perceptron artificial neural network (ANN) was implemented. Three different groups were used: Time domain characteristics, autoregressive (AR) model parameters, and representation of time frequency using Wavelet transform (WT). Results and Discussion: The experimental results of 10 healthy subjects indicate that the coefficients of the AR models offer the best parameters for classification, with a differentiation rate of 78 % for the five angular positions studied. The combination of frequency and time frequency resulted in a differentiation rate that reached 82 %. Conclusions: An algorithm based on pattern recognition of EMG signals was used to carry out a comparative study of groups of features that allow for the differentiation of the angular position of the wrist in terms of flexion-extension movements. The method has the potential for application in the field of rehabilitation engineering to detect the user’s movement intent.

scholarly journals Multichannel Biphasic Muscle Stimulation System for Post Stroke Rehabilitation

Electronics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1156
Author(s):  
Tyler Ward ◽  
Neil Grabham ◽  
Chris Freeman ◽  
Yang Wei ◽  
Ann-Marie Hughes ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Upper Limb Function ◽  
Stimulation Parameters ◽  
Average Accuracy ◽  
Pulse Timing ◽  
Field Programmable ◽  
Stimulation System ◽  
Electrical Stimulator ◽  
Mechanical Movement ◽  
Better Than

We present biphasic stimulator electronics developed for a wearable functional electrical stimulation system. The reported stimulator electronics consist of a twenty four channel biphasic stimulator. The stimulator circuitry is physically smaller per channel and offers a greater degree of control over stimulation parameters than existing functional electrical stimulator systems. The design achieves this by using, off the shelf multichannel high voltage switch integrated circuits combined with discrete current limiting and dc blocking circuitry for the frontend, and field programmable gate array based logic to manage pulse timing. The system has been tested on both healthy adults and those with reduced upper limb function following a stroke. Initial testing on healthy users has shown the stimulator can reliably generate specific target gestures such as palm opening or pointing with an average accuracy of better than 4 degrees across all gestures. Tests on stroke survivors produced some movement but this was limited by the mechanical movement available in those users’ hands.

scholarly journals OpenFES: Development of an Open-Source EMG-Triggered Functional Electrical Stimulation Controller for Physical Therapy

2010 ◽  
Vol 4 (2) ◽  
Author(s):  
Anirban Dutta ◽  
Nasir U. Ahmed
Keyword(s):  
Electrical Stimulation ◽  
Clinical Research ◽  
Open Source ◽  
Functional Electrical Stimulation ◽  
Current Source ◽  
Signal Amplitude ◽  
Surface Emg ◽  
Input Output ◽  
Stimulation Parameters ◽  
Xpc Target

The development of OpenFES hardware presented in this paper involved a closed-loop functional electrical stimulation (FES) system that could be assembled from off-the-shelf parts in India. The state-of-the-art biosignal-based control strategies could be evaluated in a clinical research setting using the familiar development environment of MATLAB/SIMULINK (The Mathworks). This hardware was developed primarily for a rehabilitation research center where students from an engineering and medical school could use it as a testbed for clinical research. It is envisioned that the design of a working prototype would be available after thorough testing at http://robo4rehab.wikispaces.com/OpenFES so that it can be further enhanced in an open-source setting. The command source selected for modulating/triggering the electrical stimulation was electromyogram (EMG), which is the recording of the bioelectrical signal generated at the cell membrane of contracting muscle fibers. The FES controller was implemented in an xPC target (The Mathworks) real-time kernel, running on a single board computer where the stimulation pattern, i.e., the temporal pattern of current pulses, was computed online based on the surface EMG patterns. The stimulation parameters were passed to a dsPIC33F microcontroller (Microchip, India) driven voltage controlled current source (VCCS) via a universal asynchronous receiver/transmitter (UART). The VCCS consisted of a coupled transconductance amplifier in series with precharged capacitors. The biphasic stimulation waveform was obtained with an analog switch that switched to reverse the polarity of the surface electrodes. The input stage for surface EMG consisted of an instrumentation amplifier with an anti-aliasing filter made of switched-capacitor (recording capacitor) banks. The dry surface EMG electrodes had buffer op-amps to provide high input impedance. A dsPIC33F microcontroller (Microchip, India) in the input/output (I/O) stage coordinated the switching of the stimulating capacitors with the recording capacitors in order to reject the stimulation artifact. The control software ran on the xPC target and delivered the stimulation parameters via UART to the dsPIC33F microcontroller (Microchip, India). The controller specifications are as follows: (1) Communications: xPC target is a battery powered stand-alone FES controller, communicating with the slave microprocessor in the input/output stages via UART. (2) FES controller: PC/104 single board computer (Advantech Co., PCM-3355) running xPC target kernel (The Mathworks). (3) PC/104 CPU: 366 MHz ×86 (AMD Geode processor). (4) Display: LCD (1024×768 at 18 bpp TFT) or CRT (1024×768 at 24 noninterlaced). (5) Stimulation pulse-width range: 1–255 ms. (6) Stimulation amplitude range: 0–100 mA (16 bit analog output with voltage controlled current source). (7) Stimulation frequency range: up to 30 Hz. (8) I/O channels (Sensoray, model 526): 4 AO (16 bit), 8 DIO, and 8 AI (16 bit). (9) Channel offset: 1000 Hz. (10) Analog to digital conversion for EMG: 16 bit. (11) Maximum signal amplitude: about 10 mV (peak to peak). (12) Minimum signal amplitude: about 1 mV (peak to peak), i.e., the noise floor should preferably be lower. (13) Signal to noise ratio.

scholarly journals A Gastrointestinal Electrical Stimulation System Based on Transcutaneous Power Transmission Technology

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Bingquan Zhu ◽  
Yongbing Wang ◽  
Guozheng Yan ◽  
Pingping Jiang ◽  
Zhiqiang Liu
Keyword(s):  
Electrical Stimulation ◽  
Power Transmission ◽  
Functional Gastrointestinal Disorders ◽  
Gastrointestinal Disorders ◽  
Stimulation Protocol ◽  
Stimulation Parameters ◽  
Parametric Studies ◽  
Stimulation System ◽  
Electrical Stimulator ◽  
Extended Power

Electrical stimulation has been suggested as a possible treatment for various functional gastrointestinal disorders (FGID). This paper presents a transcutaneous power supplied implantable electrical stimulation system. This technology solves the problem of supplying extended power to an implanted electrical stimulator. After implantation, the stimulation parameters can be reprogrammed by the external controller and then transmitted to the implanted stimulator. This would enable parametric studies to investigate the efficacy of various stimulation parameters in promoting gastrointestinal contractions. A pressure detector in the internal stimulator can provide real-time feedback about variations in the gastrointestinal tract. An optimal stimulation protocol leading to cecal contractions has been proposed: stimulation bursts of 3 ms pulse width, 10 V amplitude, 40 Hz frequency, and 20 s duration. The animal experiment demonstrated the functionality of the system and validated the effects of different stimulation parameters on cecal contractions.

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

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