• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.1-5
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• 2002

The purpose of this paper is developing a speech recognition module in a wheelchair for the sake of convenience. of the disability. For this system, we used TMS320C32 as a main processor; eliminated noise by applying Winer filler while considering characteristics of noise environment in pre-processing stage, and; extracted 12 feature patterns per france using LPC&Cepstrum. Then, we implemented the hybrid form combining DTW (Dynamic Time Warping), which is generally used for isolated words in the conventional algorithms, in the recognition Part, and NN (Neural network) to prevent any error of recognition. In this research, we achieved a recognition rate of more than 96% on isolated words when DTW and Hybrid forms were individually experimented in noise environment

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.543-554
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• 1995

This paper describes the improvement of driving stability and the control system for INMEL-VII which is motorized manual wheelchair to satisfy requirements of the disabled The INMEL-VI was based on high maneuverability of the omnidirection drive and safety But the results of field tests about two years showed some problems to the disabled in daily life such as driving stability, Pm switching noise, and rotation of motor without driving command on negative slope. To solve the problems due to an increased DC motor power and applied to direct connection method in INMEL- VII. It improved the driving circuits and set switching frequency to 5KHz to eliminate the switching noise caused by PWM control of DC motor, As compare with the INMEL-VI, INMEL-VII is improved in driving stability by transfer the weight center to forward. The results of field testing proved the improvement of the driving stability and software algorithm It has been estimated to have a hlgh practical use for powered walking aids to the disabled's daily life.

• PNF and Movement
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• v.19 no.3
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• pp.375-382
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• 2021

Purpose: The objectives of the present study were to investigate the disadvantages of tire pressure asymmetry of a wheelchair tire and recommend the criterion for appropriate tire pressure without generating negative changes in the musculoskeletal system in asymptomatic participants. Methods: Fourteen asymptomatic participants were asked to sit in pressure-controlled wheelchairs and perform desk work for 20 minutes in each tire condition. The asymmetry of the tire conditions was set as 0% difference, 25% difference, and 50% difference from the recommended pressure. The pelvic alignment and muscular recruitment represented as a flexion-relaxation ratio (FRR) were measured at pre-test, and after each condition of desk work. The displacement of the center of pressure (COP) was measured during the desk work. Results: The tire air pressure condition significantly affected the FRR and COP (P < 0.05). Both sides of the FRR values were significantly higher under the symmetrical tire conditions (0% difference) and pre-test, compared with the asymmetrical tire condition of 50% difference (P < 0.05). The mediolateral COP displacement of the asymmetrical tire conditions (25% and 50% difference) was significantly higher than that of the symmetrical tire conditions (0%) (P < 0.05). Conclusion: Asymmetrical tire conditions could cause changes in the muscle recruitment pattern of the erector spine and mediolateral COP displacement. Tire pressure asymmetry higher than 50% could be a risk factor for prevalence of back pain, so this level of asymmetry in tire pressures should be cautioned against for wheelchair users.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.11
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• pp.75-87
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• 1998

KARES (KAIST Rehabilitation Engineering System) is the rehabilitation robot system in the type of the 6 degrees of freedom robot arm mounted on the wheelchair, in order to assist the independent livelihood of the disabled and the elderly. The interface device for programming and controlling of the robot arm is essential in the rehabilitation robotic system. Specially, in the case of the manual operation of the robot arm, the user has the burden of cognition and the difficulty for the operation of the robot arm. As a remedy, color vision system for the autonomous performance of jobs is proposed, and four basic desired jobs are specified. By mounting the camera in eye-in-hand type, color vision system for KARES is set up. The desired jobs for picking up the target and moving it to the user's face for drinking are successfully performed in real-time at the indoor environment.

• Journal of Biomedical Engineering Research
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• v.41 no.5
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• pp.203-209
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• 2020

As the number of people with gait disorders increases, the demand for using wheelchairs increases and the area of a ctivity for people with disabilities expands, thereby they increasing the demand for riding comfortability in various driving environments. Therefore, this study is to develop an entry-level active suspension system that apply to wheelchairs and to evaluate its usability. The suspension applied in this paper consists of a coil spring, a shock absorber, a control module to control the strength of the shock absorber, and a road surface condition monitoring system. A wheelchair occupant secures the riding comfort by adjusting the coil strength of the shock absorber in 12 steps according to various road conditions. Therefore, the mechanical properties were evaluated through the structural analysis of the suspension system, and the tendency toward the magnitude of the road surface vibration attenuated according to the rigidity of the suspension through the vibration test was attempted. In conclusion, as a result of structural analysis of the suspension system, stress in a range lower than the yield strength of the material was generated, and the vibration test showed the effect of attenuating the vibration generated from the road surface when the stiffness of the suspension was adjusted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1067-1076
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• 2016

This paper describes the development of a hybrid-powered wheelchair (HPW) for the elderly. The proposed HPW has novel mechanical and control features compared with conventional powered wheelchairs. An ergonomic back-braking mechanism was designed in order to stop the wheels easily. In terms of control features, the HPW remarkably reduces the muscle power required by combining various assistive functions, such as wheel torque assistance, friction/inertia compensation, gravity compensation, and the one-hand driving algorithm. For wheel torque assistance, strain gauges were attached to the hand-rim in order to measure the wheel torque applied by a human. Gyroscopes and an accelerometer were attached to the wheel and chair respectively for friction and inertia compensation. An inclinometer was attached for gravity compensation and the one-hand driving algorithm was included for patients who can only use one hand. The one-hand driving algorithm controls the angular velocity of the uncontrolled wheel by using a gyroscope and pressure sensors attached to the bottom of the seat. Finally, the performance of the proposed motion assisted algorithm was verified through various experiments.

• Journal of IKEEE
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• v.25 no.2
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• pp.362-370
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• 2021

In this paper, we propose the Autonomous Stair-climbing system based on data from ToF sensors and IMU in developing stair-climbing robots to passive wheelchair users. Autonomous stair-climbing system are controlled by separating the timing of landing gear operation by location and utilizing state machines. To prove the theory, we construct and experiment with standard model stairs. Through an experiment to get the Attack angle, the average error of operating landing gear was 2.19% and the average error of the Attack angle was 2.78%, and the step division and status transition of the autonomous stair-climbing system were verified. As a result, the performance of the proposed techniques will reduce constraints of transportation handicapped.

• The Journal of the Acoustical Society of Korea
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• v.26 no.6
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• pp.250-258
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• 2007

Current speech recognition technology s achieved high performance with the development of hardware devices, however it is insufficient for some applications where high reliability is required, such as voice control of powered wheelchairs for disabled persons. For the system which aims to operate powered wheelchairs safely by voice in real environment, we need to consider that non-voice commands such as user s coughing, breathing, and spark-like mechanical noise should be rejected and the wheelchair system need to recognize the speech commands affected by disability, which contains specific pronunciation speed and frequency. In this paper, we propose non-voice rejection method to perform voice/non-voice classification using both YIN based fundamental frequency(F0) extraction and reliability in preprocessing. We adopted a multi-template dictionary and acoustic modeling based speaker adaptation to cope with the pronunciation variation of inarticulately uttered speech. From the recognition tests conducted with the data collected in real environment, proposed YIN based fundamental extraction showed recall-precision rate of 95.1% better than that of 62% by cepstrum based method. Recognition test by a new system applied with multi-template dictionary and MAP adaptation also showed much higher accuracy of 99.5% than that of 78.6% by baseline system.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.3
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• pp.68-73
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• 2002

This study has been advanced to the design method for embodying the hydraulic circuit and control device in considering the safety for the development of wheelchair lift, using in the public transportation bus. Recently, mobility and accessibility occurs for the elder and the handicapped in the aging problem, In this paper, we design the hydraulic power system to operate lifter loading one wheelchair handicapped person and one's supporter to get in the bus. We develop the lifter safely. We check the trajectories of lifter inside frame box to protect its corrosion and the stress at the joints of mechanical structure. Those can be helped to keep the safety and accuracy of the multiple dynamic systems for precision quality assurance in mass production.

• Journal of Biomedical Engineering Research
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• v.32 no.4
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• pp.336-344
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• 2011

This article describes a new recognition algorithm using correlation coefficient for intelligent wheelchair to avoid collision for elderly or disabled people. The correlation coefficient can be used to represent the relationship of two different areas. The algorithm has three steps: Firstly, we extract an edge vector using the Histogram of Oriented Gradients(HOG) which includes gradient information and unique magnitude for each cell. From this result, the correlation coefficients are calculated between one cell and others. Secondly, correlation coefficients are used as the weighting factors for normalizing the HOG cell. And finally, these features are used to classify or detect variable and complicated shapes of two wheelers using Adaboost algorithm. In this paper, we propose a new feature vectors which is calculated by weighted cell unit to classify with multiple view-based shapes: frontal, rear and side views($60^{\circ}$, $90^{\circ}$ and mixed angle). Our experimental results show that two wheeler detection system based on a proposed approach leads to a higher detection accuracy than the method using traditional features in a similar detection time.