• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.8
• /
• pp.814-823
• /
• 2011

Nowadays many neurological diseases such as stroke and Parkinson diseases are continually increasing. Orthotic devices as well as exoskeletons have been widely developed for supporting movement assistance and therapy of patients. Robotic knee orthosis can compensate stiff-knee gait of the paralyzed limb and can provide patients consistent assistance at wearable environments. With keeping a robotic orthosis wearable, however, it is not easy to develop a compact and safe actuator with fast rotation and high torque for consistent supports of patients during walking. In this paper, we propose a novel kinematic model for a robotic knee orthosis to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The suggested kinematic model is composed of a hamstring device with a slide-crank mechanism, a quadriceps device with five-bar/six-bar links, and a patella device for knee covering. The quadriceps device operates in five-bar links with 2-dof motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The kinematics and velocity/force relations are analyzed for the quadriceps and hamstring devices. Finally, the adequate actuators for the suggested kinematic model are designed based on normal gait requirements. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking.

• Proceedings of the KOSOMBE Conference
• /
• v.1991 no.11
• /
• pp.70-74
• /
• 1991

좌심실보조기의 임상응용범위를 넓히기 위해서 개심술을 하지 않고 좌심실보조기를 적용할 수 있도록 캐뉼라형 좌심실보조기를 이용한 보조순환 실험을 하였다. 좌심실 보조기는 모터의 회전력이 PVC 벨로우즈를 수측, 팽창시키는 전기유압식으로 구동되며 환자는 양쪽 대퇴동맥을 통하여 보조순환을 받도록 되어 있다. 두차례의 동물실험을 통하여 대퇴동맥을 통한 보조 순환방식의 가능성 및 그 효과에 대해서 관찰하였다. 첫 실험은 12kg 개를 이용하여 셀딩거 방법으로 뮬린형 카테터를 디퇴동맥으로 삽입히여, 캐뉼라형 보조순환방법의 가능성을 확인하였고, 두번째 동물실험에서는 내경 4.8 mm의 PVC 카테터를 이용하여 좌심방에 유입카테터를 연결하고 대동맥에 유출카테터를 연결하여 보조순환에 의한 대동맥압의 변화와 혈류량의 변화를 관찰하였다. 보조순환동안 개의 동맥압을 100mmHg로 유지할 수 있었으며, 좌심실내압이 감소하는 것을 관찰할 수 있었다.

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

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.6
• /
• pp.1064-1071
• /
• 2006

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control based on disturbance observer and sensor-less vector control. The numerical simulation and experimental results point out that the proposed readhesion control system has the desired driving wheel torque response for the tested bogie system of electric coach. Based on this estimated adhesive effort, the re-adhesion control is performed to obtain the maximum transfer of the tractive effort.

• Journal of IKEEE
• /
• v.24 no.4
• /
• pp.1104-1108
• /
• 2020

This paper propose a variable proportional resonant feedforward algorithm for reducing the speed ripple of a three-phase permanent magnet synchronous motor. In general, the torque ripples can be generated by electrical pulsation due to current measurement errors and dead time and mechanical pulsation because of rotor eccentricity and eccentric load. These torque pulsations can cause speed pulsations of the motor and degrade the operating performance of the motor drive system. Therefore, in this paper, the factors of the speed ripple is analyzed and an algorithm to reduce the speed ripple is proposed. The proposed algorithm applied a variable proportional resonant controller in order to reduce the specific operating frequency included in the speed pulsation, and utilized a feedforward compensation controller structure to perform the compensation operation. The proposed algorithm is verified through various experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.2
• /
• pp.123-128
• /
• 2022

The torque of the SRM((Switched Reluctance Motor)) is proportional to the inductance slope, so it has a non-linear torque characteristic, and has a disadvantage in that the torque pulsation is large and noise is severe. In particular, the biggest obstacle to the commercialization of SRM is the pulsating torque generated from the rotating shaft, which has various adverse effects not only on the device itself but also on the peripheral devices. Therefore, various methods for reducing the pulsating torque have been published by domestic and foreign researchers, and there is a study result that the hysteresis controller has an advantage in that it can flow a smooth current compared to the chopping control. However, in determining the hysteresis band, if the band is too small, it has a disadvantage in that it may cause a switching loss due to many switching and an unstable initial start when the encoder is used. Therefore, in this paper, a variable hysteresis controller that can reduce torque ripple in a steady state while having a more stable and fast speed response through the change of the hysteresis band according to the speed error.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.919-925
• /
• 2023

Modern drones are equipped with miniaturized mission equipment capable of performing various tasks such as surveillance and reconnaissance. Consequently, these mission equipment are exposed to disturbances like wind loads and motor rotations, which can lead to instability in the operation of the Electro-Optical Targeting System (EOTS). Specifically, simple step inputs for changing the line of sight in EOTS can cause abrupt changes in speed, inducing overshoot and potentially creating instability along with other disturbances. To address this, a velocity profile was designed so that the angular velocity moves in a trapezoidal shape when changing the EOTS line of sight. A Double-loop controller was designed to apply this profile as an input to the external loop receiving position feedback. The system's stability was then compared, and the velocity profile was optimized within a stable range by varying maximum speed and acceleration.

• Aerospace Engineering and Technology
• /
• v.6 no.1
• /
• pp.74-82
• /
• 2007

The M-Method that measures the speed of actuator with counting the number of Reaction wheel Tacho Pulse has the many advantages such that a realization is simple and measuring time is uniform, but it also has the disadvantage that measuring speed becomes worse as the wheel speed goes lower. On the contrary, the T-Method that measures the time duration between the pulses is more accurate at lower-speed and its time delay is smaller than M-Method, but its realization is more difficult than M-Method because measuring time is varying with wheel speed variation. Thought M/T Method mixing M-Method with T-Method is widely used in order to measure the speed in the motor industrial area, one of two methods has been used in the spacecraft design area. Therefore, we try to apply both methods together to measuring the speed of Reaction Wheel, the core actuator for low earth orbit satellite. This paper provides the Reaction Wheel simulation board located in the Spacecraft Dynamic Simulator, ground support test set.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.578-585
• /
• 2018

This paper proposes a design method for a 3-phase interior permanent magnet synchronous motor (IPMSM) and clamping force control method for an electro-mechanical brake (EMB) using co-simulation for a high-speed train (HST). A traditional pneumatic brake system needs much space for the compressor, brake reservoir, and air pipe. However, an EMB system uses up to 50% less space due to the use of a motor and electric wires for controlling the brake caliper. In addition, it can reduce the latency time for brake control because of the fast response and precise control. A train that has many brakes is advantageous for safety because of the control by sharing the braking force. In this paper, a driving method for a cam-shaft-type EMB is modeled. It is different from the ball-screw-type brakes that are widely used in automobiles. In addition, a co-simulation method is proposed using JMAG and Matlab/Simulink. The IPMSM was designed and analyzed with the JMAG tool, and the control system was simulated using Matlab/Simulink. The effectiveness of the co-simulation results of the mechanical clamping force and braking force was verified by comparison with the clamping force specifications of a HEMU-430X HST.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.851-860
• /
• 2020

With an increase in the aging population and a rising social interest in health and welfare, studies to improve healthcare in the elderly are being actively conducted. This study attempted to improve the current design and manufacture of elevating electric wheelchairs to enhance user safety and convenience. Seat design based on the user's body shape, convenience while boarding or alighting, caster turning radius and, safety and stability features that prevent shaking when the user gets up or sits down were improved. A driving experiment was conducted to evaluate the operation of the indoor electric wheelchair designed and manufactured with these additional functionalities. During the test, the performance parameters evaluated were continuous driving time, turning radius, maximum lifting and lowering load, maximum lifting height, noise level, minimum distance sensing by the driving auxiliary sensor, ability to interact with server and app programs, and the duty cycle maximum error rate. The test confirmed that this improved electric wheelchair successfully met target parameters. In a future study, we will evaluate this improved electric wheelchair from a user's perspective for its usability parameters, such as satisfaction, convenience and stability.