• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.3027-3029
• /
• 1999

인간과 함께 협력하는 서어비스 산업에서 요구되는 로봇은 고정된 환경에서 단순 반복 작업을 하는 기존 산업용 로봇의 개념을 뛰어 넘어 변화하는 환경에서 이동하면서 물체 이송 및 조작 기능을 수행하는 작업 형태를 취한다. 일반적으로 서어비스 로봇은 이동 능력과 조작능력이 겸비된 mobile manipulator의 외양을 갖는 것이 가장 응용 분야가 넓다. 이러한 mobile manipulator는 구동 축만 10축 내외가 되므로 축별 서보 제어기와 종류별 센서 제어기들을 분산화 시키는 구조가 신뢰성, 연산 능력의 측면에서 바람직하다. 개방형 구조로써 서보 제어기와 센서 제어기의 결합에 따른 비용 절감을 위하여 저가의 고속 통신망을 사용하고, 제어기 구성 요소들의 수급 다양화와 보수 유지의 간편화를 위하여 개방화된 인터페이스 하드웨어를 채택한다. 또한 자체 동력원에 의해 구동되는 것이 작업범위에 제한을 가하지 않으므로 로봇 제어기가 로봇 내부에 실장되어 오랜 시간 운용 가능하도록 소형화된 구조를 지니도록 설계한다.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.9
• /
• pp.622-629
• /
• 2004

In practical control systems, the capacity of actuators is limited and this degrades the system performances and it is often a source of instability. To use full capacity of actuators, we adopt the gain scheduled control permitting the over saturation in controls. The basic idea of gain scheduled control is to use a higher gain control when the state variables are smaller and a lower gain control when the state variables are larger. First, we derive a constant H control and a reachable set while satisfying the degree of over saturation. Next, we divide this set into nested subsets and find $H_{\infty}$ controls at rack subsets while satisfying the degree of over saturation. Finally, the control gain is applied according to the status of states. Note that all procedures are done by solving linear matrix inequalities(LMI). Finally, we show the validity and applicability of our proposed control using the simulations of a six-story building subjected to the earthquake excitation.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.270-273
• /
• 2002

복수구동장치를 사용하여 작업을 수행하는 시스템은 동기화를 위해 기계적인 제한조건을 두고 운용하는 경우 지속적인 유지보수가 요구되고 작업 정밀도가 떨어진다 이러한 단점을 보완하기 위해 개별적인 구동장치의 제어루프 외부에 동기화를 위한 제어루프를 추가하는 방법이 제안되었다. 본 논문에서는 CAN(Controller Area Network)으로 연결된 두 대의 서보앰프를 구동하여 주어진 작업을 수행하는 경우 외란과 내부 파라미터 변동에 강인한 $H^{\infty}$ 제어기를 설계하고 이를 이용하여 동기제어 알고리즘을 구현하고자한다.

• Proceedings of the KIPE Conference
• /
• 2019.07a
• /
• pp.86-88
• /
• 2019

본 논문에서는 고주파수 구동 및 고전력밀도 아답터의 경부하 효율 개선을 위한 One Chip 디지털 통합제어 알고리즘을 제안한다. 제안 회로는 CRM PFC Boost 컨버터와 3-Level LLC 공진형 컨버터를 하나의 소형 MCU로 구성된 디지털 제어기를 사용함으로써 고주파수 구동을 가능케 하며, 주파수 제한 및 Burst mode로 구성된 알고리즘을 통해 높은 스위칭 주파수로 인해 발생하는 경부하 시 효율 개선을 통해 수동 소자와 제어단 부피 저감으로 고 전력밀도 달성이 가능하다. 최종적으로 제안 회로의 타당성 검증을 위하여 200W급 아답터의 전원회로를 위한 시작품을 제작하여 고찰된 실험결과를 제안한다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.7
• /
• pp.919-928
• /
• 2010

Four patterns for width adjustment were studied with an aim to increase the width-adjustment speed in continuous casting. The main goals are to minimize the actuating force of a WAM actuator, to develop a deformation analysis model of a solidified shell in the mold, and to induce the main limit factor for the speedup of width adjustment. On the basis of the width-adjustment experiment, the notable features of four patterns types were considered, and we compared the corresponding actuating forces. For comparing the driving forces of the patterns, during the experiment, the same casting speed was maintained for each pattern. To optimize the parameter of the deformation analysis model of the solidified shell, the experiment results were applied to them. To speed up width adjustment and to reduce the driving force, we controlled the pattern parameters. The most effective pattern was the fast-mode pattern, and the taper was the main parameter that helped reduce the driving forces during the motion of the actuator.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.11
• /
• pp.4483-4488
• /
• 2010

In comparison with some other light sources, LED has merits such as long lifetime, pollution free, and high energy efficiency. Lately, due to development of LED with high brightness and capacity, LED, which has been applied in display system only, has applied in the field of lighting system. Driving current of power LED has to be controlled below the designed value. In this paper, half-bridge LLC series resonant converter, which has the current limiting function, has been described. Half-bridge LLC series resonant converter allows in relatively wide input voltage and output load range when compared to the other resonant converter. Also, it is possible to reduce a magnetic component, because leakage inductance of transformer is used as a resonant inductance. It has been validated by designing and testing 200[W] half-bridge LLC converter of DC24[V] output voltage for LED lamp driver, which includes a current limiting function and power factor correction(PFC) function.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.198-202
• /
• 2005

Gas generator is the equipment to produce high enthalpy gas used to generate sufficient power to operate turbine and pump system for propellant feeding in liquid rocket engine. Since the limit in operating temperature is imposed due to turbine blade, the gas generator has to be operated at the temperature far below stoichiometric maintaining fuel rich combustion. In this research, fundamental study was performed to understand the non-equilibrium combustion process with in-house code and CFD-ACE as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.8
• /
• pp.639-651
• /
• 2018

An analytical solution to generate attitude command profile for agile spacecraft is proposed. In realistic environment, obtaining analytical minimum-time optimal solution is very difficult because of following constraints-: 1) actuator saturation, 2) flexible mode excitation, 3) uplink command bandwidth limit. For that reasons, this paper applies two simplifications, an eigen-axis rotation and a finite-jerk approximated profile, to derive the solution in an analytical manner. The resulting attitude profile can be used as a feedforward or reference input to on-board attitude controller, and it can enhance spacecraft agility. Equations of attitude command profile are derived in two general boundary conditions: rest-to-rest maneuver and spin-to-spin maneuver. Simulation results demonstrate that the initial and final boundary conditions, in terms of time, attitude, and angular velocities, are well satisfied with the proposed analytical solution. The derived attitude command generation algorithm may be used to minimize a number of parameters to be uploaded to spacecraft or to automate a sequence of attitude command generation on-board.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.9
• /
• pp.73-80
• /
• 2005

This paper addresses a newly proposed start-up method of the HAUSAT-2 momentum wheel. The HAUSAT-2 is a 25kg class nanosatellite which is stabilized to earth pointing by 3-axis active control method. A momentum wheel performs two functions. It provides a pitch-axis momentum bias while measuring satellite pitch and roll attitude. Pitch control is accomplished in the conventional way by driving a momentum wheel in response to pitch attitude errors. Precession control and nutation damping are provided by driving the pitch axis magnetic torquer. A momentum wheel is nominally spinning at a particular rate and changes speed. This simulation study investigates the feasibility and performance of a proposed strategy for starting-up the wheel. A proposed strategy to start-up the wheel shows that a pitch momentum wheel can be successfully started-up to its nominal speed from rest and be stabilized to nadir pointing.

• Proceedings of the KIPE Conference
• /
• 2011.11a
• /
• pp.14-15
• /
• 2011

본 논문에서는 단상입력을 가지고, 직류단에 소형 캐패시터를 사용하는 인버터를 사용해 3상 전동기 가변속 구동을 한다. 이때 주기적으로 크게 맥동하는 직류단 전압 조건에서 어떻게 전동기를 제어하는가에 대해 언급한다. 평균 전압 제한원을 전류 영역에 표현하고, 새로운 약자속 영역을 정의한다. 이를 바탕으로 전류 지령을 생성하는 제어기를 구성하여 전동기를 제어할 수 있는 기법을 제안하고 이를 실험을 통해 검증한다. 이를 통해 입력 전류의 고조파를 줄여 역율도 개선할 수 있다.