• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.241-250
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• 2023

This paper describes the posture stabilization control of a bipedal transformer robot being developed for military use. An inverted pendulum model with a rectangular that considers the robot's inertia is proposed, and a posture stabilization moment that can maintain the body tilt angle is derived by applying disturbance observer and state feedback control. In addition, vertical force and posture stabilization moments that can maintain the body height and balance are derived through QP optimization to obtain the necessary torques and vertical force for each foot. The roll and pitch angles of the IMU sensor attached to the robot's feet are reflected in the ankle joint to enable flexible adaptation to changes in ground inclination. Finally, the effectiveness of the proposed algorithm in posture stabilization is verified by comparing and analyzing the difference in body tilt angle due to disturbances and ground inclination changes with and without algorithm application, using Gazebo dynamic simulation and a down-scale test platform.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.614-619
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• 2004

The line-of-sight (LOS) stabilization system is a precision electro-mechanical gimbals assembly for rejecting vibration to isolate the load from its environment and point toward the target in a desired direction. This paper describes the design of gimbals system to reject the disturbance and to improve stabilization. To generate movement commands for the actuators in the stabilization system, the control system uses a sensor of angular rotation. The controller is a DSP with transducer and actuator interfaces. Unknown parameters of the gimbals are estimated using the signal compression method. The cross-correlation coefficient between the impulse response from the assumed model and the one from model of the gimbals is used to obtain the better estimation. And SMCPE (sliding mode control with perturbation estimation) is used to control the gimbals. SMCPE provides robustness of the control against the modeling deficiencies and unknown disturbances. In order to compare the performance of SMCPE with the classical SMC, a sample test result is presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1555-1561
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• 2018

Tracking and detecting targets by the millimeter wave seeker is affected by movement of platform. Stabilization equipments use an inertial sensor to compensate for disturbance of stabilizing gimbal or platform. In the direct line of sight stabilization system, an inertial sensor is mounted on inner gimbal to compensate the disturbance directly, so the performance is excellent and the implementation method is simple. However gimbal design requires somewhat larger volume. Since an inertial sensor is mounted on gimbal base in the indirect line of sight stabilization system, additional space of gimbal is not required for the gimbal design. However, this method does not directly compensate for the disturbance of the line of sight stabilization axis, which can degrade performance. In order to perform the tracking performance, two methods are analyzed for line of sight stabilization performance based on direct and indirect of a 2-axis gimbaled servo system for millimeter wave seeker in this study. The simulation and experimental results validate the performance comparison of two methods.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.1
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• pp.107-113
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• 2015

PURPOSE: This study was to investigate the effect of stabilization exercise with abdominal breath on Balance and Oswestry Disability Index for Low Back Pain Patients. METHODS: The subjects were 18 low back pain patients in their twenties. The subjects were randomly assigned into experimental group and control group. Control group and experimental group both participated in 30 minutes of stabilization exercise for 8 weeks(5 times/week), and experimental group participated in stabilization exercise with abdominal breath. The subjects were tested balance and pain using BioRescue and Oswestry Diability Index respectively, before and after intervention. RESULTS: The experimental group showed a statistical significance in movement areas of the body's center(p<.05), but there was no significant differences between groups (p>.05). The experimental group showed a statistical significance in movement distances of the body's center with eyes open(p<.05), and there was significant differences between groups(p<.05). Both groups showed a statistical significance in ODI between pre and post test(p<.05) but there was no significant differences between groups(p>.05). CONCLUSION: As a result, the group participating in stabilization exercise with abdominal breath had a more effective improvement than the control group. Therefore, the stabilization exercise with abdominal breath may be used improving balance and pain in low back pain patients.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.121-127
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• 2009

This paper deals with the design problem of robust stabilization and non-fragile controller for discrete-time singular systems with parameter uncertainties and time-varying delays in state and input by delay-dependent Linear Matrix Inequality (LMI) approach. A new delay-dependent bounded real lemma for singular systems with time-varying delays is derived. Robust stabilization and robust non-fragile state feedback control laws are proposed, which guarantees that the resultant closed-loop system is regular, causal and stable in spite of time-varying delays, parameter uncertainties, and controller gain variations. A numerical example is given to show the validity of the design method.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.1
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• pp.29-35
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• 2012

Purpose : The purpose of this study was to investigate effect of the lumbo-pelvic stabilization exercise on relief of menstrual pain and premenstrual syndrome of the female university students. Methods : Thirty female students with dysmenorrhea were participated in this study. Subjects divided into experimental group(n=15) and control group(n=15). Experimental group were given lumbo-pelvic stabilization exercise and control group didn't have any application to exercise. Menstrual pain measured by VAS(Visual Analogue Scale) and premenstrual syndrome measured by MDQ(Moos Menstrual Distress Questionnaire) scale. Results : The experimental group were significantly improved menstrual pain and symptoms of premenstrual syndrome, but negligible changes were found in the control group. Conclusion : This study show that lumbo-pelvic stabilization exercise is beneficial intervention for decrease menstrual pain and premenstrual syndrome.

• The Journal of Korean Physical Therapy
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• v.27 no.6
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• pp.419-424
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• 2015

Purpose: This study aimed to evaluate the effects of lumbar stabilization exercise on the abdominal muscle-back muscle ratio in white-collar workers. Methods: Forty white-collar workers without any pain who worked at an information technology (IT) company located in the Gyeonggi province were included in this study. Of these, 20 subjects were randomly allocated to the lumbar stabilization exercise group, whereas the remaining 20 were randomly allocated to the control group. The lumbar stabilization exercise group performed a 40-minute-long exercise once a week for 8 weeks. The strength of the abdominal and back muscles was measured using the CENTAUR 3-D Spatial Rotation Device (BFMC, Germany). Data analysis was conducted using SPSS 18.0 for Windows. The Paired t-test was performed to compare the values measured before and after exercise within each group. The independent sample t-test was performed to analyze the differences between the 2 groups. The statistical significance for all the analyses was set at .05. Results: The strength of the abdominal muscles after the exercise significantly differed between the lumbar stabilization exercise group and the control group (p<0.05). However, the increase in the abdominal muscle-back muscle ratio was significant in only the lumbar stabilization exercise group (p<0.05), but not in the control group (p>0.05). Conclusion: The improvement of the abdominal muscle-back muscle ratio through lumbar stabilization exercise may have positive effects on lumbar stabilization. Moreover, lumbar stabilization exercise is considered beneficial for the prevention of back pain and musculoskeletal diseases.

• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.179-188
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• 2018

BACKGROUND: Reclamation of heavy metal-contaminated agricultural fields has intensively been done to ensure the soil quality and food security. This study evaluated the efficiency and longevity of current physical and chemical approaches for heavy metal-contaminated soils. METHODS AND RESULTS: Concentrations of 0.1 N HCl-leachable trace metals of Cd, Pb, and As from the stabilizing agents-treated soils decreased by 50%, 70%, and 40%, respectively, compared to the control. Among the stabilizing agents, the $CaCO_3$ was the best for stabilization. For physical stabilization, the soil dressing reduced the concentrations of Cd, Pb, and As by 88%, 94%,and 88%, respectively, compared to the control. Moreover, the dilution of the contaminated soils decreased the metals by an average of 25.3% when compared with the control. The longevity of each stabilization method was determined by using the availability assessment of heavy metals in the soils. Results showed that the leaching methods using HCl and $NH_4NO_3$ had 120 and 32 weeks longevity, respectively. Interestingly, any stabilization efficacy was not found over the time for Cd and Pb (i.e., cation metals), whereas the stabilization efficacy of As was sharply decreased under 50% after 32 weeks. However, the change of metal concentration was not significant with the physical stabilization compared to the chemical stabilization. CONCLUSION: The stabilization methods should carefully be selected based on long-term monitoring under climate conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.11 s.104
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• pp.1303-1310
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• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.3
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• pp.67-72
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• 2015

PURPOSE: This study was conducted to examine the effects of motion taping on the effects of lumbar stabilization exercise. METHODS: The subjects of this study were 24 normal males with no problem in their nervous systems or musculoskeletal systems. The subjects were randomly assigned to a control group of 12 subjects and an experimental group of 12 subjects. The control group was applied with lumbar stabilization exercise while the experimental group was applied with lumbar stabilization exercise after being attached with tapes. The intervention period was four weeks in total and the subject underwent the exercises three times per week. The exercise time per session was set to one hour in principle consisting of warm-up exercise and cool-down exercise for 10 minutes each and main exercise for 40 minutes. Lumbar muscle strength was measured as a factor to examine the effects of lumbar stabilization exercises. RESULTS: The control group showed an increase in lumbar muscle strength from $111{\pm}6.30kg$ to $113{\pm}6.23kg$ and the experimental group showed an increase in lumbar muscle strength from $108{\pm}6.46kg$ to $116{\pm}5.21kg$. The increases shown by both groups were statistically significant and the experimental group that was applied with motion taping showed a larger increase in lumbar muscle strength compared to the control group. CONCLUSION: Lumbar stabilization exercise is considered to be good for lumbar stability and muscle strengthening and lumbar stabilization exercise applied with motion taping is considered to show larger effects for muscle strengthening and the improvement of lumbar functions.