• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.2
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• pp.107-119
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• 2013

We study three axis attitude control method including two axis high agile maneuver using four reaction wheels and two control moment gyros. We investigate singularity conditions due to two control moment gyros and propose singularity escape method. Based on this, we propose actuator control algorithm for high agile maneuver. Also, we propose actuator momentum management method which preserves momentum of reaction wheels and control moment gyroscopes before and after satellite attitude control. Through numerical simulation, we show that our method achieves three axis attitude control including two axis high agile maneuver and preserves actuators' momentum.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.67-72
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• 2001

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axes driving system has been developed. The synchronous error is caused by model uncertainties and torque disturbance of each axis. To overcome these problems, the proposed synchronous control system has been composed of two speed controllers, disturbance observers, and one synchronous controller. The speed controllers, based on the PID control law are aimed at the following to speed reference. And the parameters of speed controllers have been designed in order for the speed response fo the second axis to correspond with the one of the first axis. The disturbance observer has been designed to restrain the torque disturbance. The synchronous controller eliminates the synchronous error by controlling the speed of the second axis. The effectiveness of the proposed method has been verified through simulation.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.192-198
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• 2001

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axes driving system has been developed. The synchronous error is caused by model uncertainties and torque disturbance of each axis. To overcome these problems, the proposed synchronous control system has been composed of two speed controllers and one synchronous controller. The speed controllers based on PID control law are aimed at the following to speed reference. And the parameters of speed controllers have been designed in order that speed response of the second axis corresponds with one of first axis. Especially, considering to model uncertainties of each axis, the synchronous controller has been designed using H$\infty$ control theory. The controller eliminates the synchronous error by controlling speed of the second axis. The effectiveness of the proposed method has been verified through simulation.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.110-115
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• 2016

This paper describes the design and fabrication of a three-axis force sensor with three parallel plate structures(PPSs) for measuring force in a finger force measuring system for a spherical object catch. The three-axis force sensor is composed of a Fx force sensor, Fy force sensor and a Fz force sensor, and the elements of Fx force sensor and Fy force sensor are a parallel plate structure(PPS) respectively and Fz force sensor is two PPS. The three-axis force sensor was designed using FEM(Finite Element Method), and manufactured using strain-gages. The characteristics test of the three-axis force sensor was carried out. As a test results, the interference error of the three-axis force sensor was less than 1.32%, the repeatability error of each sensor was less than 0.04%, and the non-linearity was less than 0.04%.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.148-154
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• 2016

This paper describes the design and fabrication of a two-axis force/torque sensor and an one-axis force sensor with parallel plate beams(PPSs) for measuring forces and torque in an ankle rehabilitation exercise using by a lower rehabilitation robot. The two-axis force/torque sensor is composed of a Fy force sensor and Tz torque sensor and the force sensor detects x direction force. The two-axis force/torque sensor and one-axis force sensor were designed using by FEM(Finite Element Method), and manufactured using strain-gages. The characteristics experiment of the two-axis force/torque sensor and one-axis force sensor were carried out respectively. As a test results, the interference error of the two-axis force/torque sensor was less than 1.56%, the repeatability error and the non-linearity of the two-axis force/torque sensor were less than 0.03% respectively, and the repeatability error and the non-linearity of the one-axis force sensor were less than 0.03% and 0.02% respectively.

• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.114-121
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• 2017

This paper describes the design and fabrication of a three-axis force sensor with parallel plate beams (PPSs) for measuring the calf force while a patient with a walking assist robot is walking. Current walking assist robots can't measure the weight of the patient's leg and the robot's leg which required for robot control. So, the three-axis force sensor in the calf link is designed and manufactured, it is composed of a Fx force sensor, a Fy force sensor and a Fz force sensor. The three-axis force sensor was designed using by FEM(Finite Element Method), and fabricated using strain-gages. The characteristics experiment of the three-axis force sensor was carried out respectively. The test results indicated that the repeatability error and the non-linearity error of three-axis force sensor was less than 0.04% respectively. Therefore, the fabricated three-axis force sensor in the calf link can be used to measure the patient's calf force in the walking assist robot.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.63-71
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• 2003

This paper presents a robust slewing control of a flexible space structure based on sliding surface design. A sliding surface is designed for a single-axis rest-to-rest slewing in view of target angle, target angular velocity, and root monent of the flexible appendage. In comparison with the Lypunov control law, both controllers guarantee the stability and command tracking capabilities for nominal system. It is also shown that the designed control law provides further robustness to internal/external uncertainties. Extending the results of a single-axis maneuver, a sliding mode control law was sought for an arbitrary three-axis maneuver. Quaternion was used to determine the attitude of a space structure and sliding surfaces were designed for each axis, thereby a robust control law was derived considering the coupling effects between each rotational axis during the maneuver. Several numerical examples were demonstrated to show the effectiveness of the designed control law.

• Journal of Sensor Science and Technology
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• v.21 no.2
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• pp.127-134
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• 2012

Stroke patients must do the rehabilitation exercise to recover their fingers' function using a rehabilitation robot. But the rehabilitation robots mostly have not the force sensors to control the applied force to each finger. Thus, in this paper, the development of a force sensor for thumb rehabilitation robot and four two-axis force sensors for four-finger rehabilitation robot were developed. The force sensor and four two-axis force sensors could be used to measure the applied force to each finger, and the forces could be used to control the applied forces to each sensor in rehabilitation exercise using in the rehabilitation robot. The developed sensors have non-linearlity error of less than 0.05 %, repeatability error of less than 0.03 %, and the interference error of two-axis force sensor is less than 0.2 %.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.333-334
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• 2010

• International Journal of Control, Automation, and Systems
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• v.5 no.4
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• pp.419-428
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• 2007

This paper describes the development of a six-axis force/moment sensor with rectangular taper beams for an intelligent robot's wrist and ankle. In order to accurately push and pull an object with an intelligent robot's hand, and in order to safely walk with an intelligent robot's foot, the robot's wrist and ankle should measure three forces Fx, Fy, and Fz, and three moments Mx, My, and Mz simultaneously from the mounted six-axis force/moment sensor to the intelligent robot's wrist and ankle. Unfortunately, the developed six-axis force/moment sensor utilized in other industrial fields is not proper for an intelligent robot's wrist and ankle in the size and the rated output of the six-axis force/moment sensor. In this paper, the structure of a six-axis force/moment sensor with rectangular taper beams was newly modeled for an intelligent robot's wrist and ankle, and the sensing elements were designed by using the derived equations, following which the six-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements. Moreover, the characteristic test of the developed sensor was carried out by using the six-component force/moment sensor testing machine. The rated outputs from the derived equations agree well with those from the experiments. The interference error of the sensor is less than 2.87%.