• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.03a
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• pp.347-350
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• 1999

자율무인잠수정은 자율운항을 위해서 자동화된 제어시스템이 필요하다. 제어시스템은 기능적 측면에서 임무계획단계(mission planning level), 임무제어단계(mission control level), 선체제어단계(vehicle control level)로 구분한다. 자율무인잠수정의 효과적인 임무 수행을 위해서는 임무제어단계의 운행 경로 설정과 제어가 중요하다. 자율무인잠수정은 잠수정의 주변환경을 추상화한 후 탐색기법을 이용하여 경로를 설정한다. 이때 검색기법의 효율적 적용을 위해서는 효과적으로 추상화된 탐색모형이 필요하다. 대표적인 탐색모형으로는 3차원 격자절대좌표 모형(3-dimensional grid unit coordinate model)[1]을 들 수 있다. 그러나 이 모형은 불필요한 동작의 반복, 이동 격자에 따른 비일관성과 같은 취약점이 존재한다. 본 연구에서는 이 모형의 취약점을 개선하기 위해서 자유무인잠수정의 위치 기반 상대적 격자좌표 모형(relative grid unit coordinate model based on AUV state)을 제안한다.

• Journal of IKEEE
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• v.24 no.4
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• pp.954-960
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• 2020

This paper proposes a speed variable proportional resonant current control method for a single-phase permanent magnet synchronous motor(PMSM). Due to the electromagnetic characteristics of a single-phase PMSM, negative and zero torques are generated in the part corresponding to the phase difference between the stator current and the back electromotive force. In addition, overcurrent limitation is required because of the low stator resistance and inductance in sensorless operation. When using the vector control for current control of single-phase PMSM under these conditions, processes of coordinate transformation, inverse coordinate transformation, and generation of virtual dq-axis components are required. However, the proposed variable speed proportional resonant current control method does not need the coordinate transformation used for AC motors. In this paper, we have confirmed stable maneuverability by using variable proportional resonant current control algorithm, and proposed sensorless control based on a mathematical model of a single-phase PMSM without a position sensor when reaching a constant speed. The usefulness of the current control method was verified through several experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1327-1332
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• 2003

In this paper, an ATC(Automated Transfer Crane) control system is required rapid transportation to get highest productivity with low cost. Therefore, the container paths should be built in terms of the least time and least sway when container is transferred from the initial coordinate to the finial coordinate. So we applied the best-first search method for forming the container path, and calculated the anti-collision path for avoiding collision in its movement to the finial coordinate. And we constructed the neural network two degree of freedom PID (TDOFPID) controller to control the precise navigation. For simulation, we constructed the container profiles so that we analyzed the state of formed path and the performance of TDOFPID controller to the formatted path. Then we compared the performance of ES-tuned PID controller with our proposed controller in terms of trolley position, anti-sway, path change, disturbance, and the load of containers. The computer simulation results show that the proposed controller has better the other on the various conditions.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2456-2458
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• 2003

Recently, an automatic crane control system is required with high speed and rapid transportation. Therefore, when container is transferred from the initial coordinate to the finial coordinate, the container paths should be built in terms of the least time and without sway. Therefore, we calculated the anti-collision path for avoiding collision in its movement to the finial coordinate in this paper. And we constructed the neural network predictive two degree of freedom PID (NNPPID) controller to control the precise navigation. The proposed Predictive control system is composed of the neural network predictor, two degree of freedom PID(TDOFPID) controller, neural network self-tuner which yields parameters of TDOFPID. We analyzed crane system through simulation, and proved excellency of control performance over the conventional controllers.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1347-1356
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• 2018

In a three-phase system, three-phase AC signals can be translated into two-phase DC signals through a coordinate transformation. Thus, the PI regulator can realize a zero steady-state error for the DC signals. In the control of a three-phase grid-connected inverter, the phase angle of grid is normally detected by a phase-locked loop (PLL) and takes part in a coordinate transformation. A novel control strategy for a three-phase grid-connected inverter with a frequency-locked loop (FLL) based on coordinate transformation is proposed in this paper. The inverter is controlled as a current supply. The grid angle, which takes part in the coordinate transformation, is replaced by a periodic linear changing angle from $-{\pi}$ to ${\pi}$. The changing angle has the same frequency but a different phase than the grid angle. The frequency of the changing angle tracks the grid frequency by the negative feedback of the reactive power, which forms a FLL. The control strategy applies to non-ideal grids and it is a lot simpler than the control strategies with a PLL that are applied to non-ideal grids. The structure of the FLL is established. The principle and advantages of the proposed control strategy are discussed. The theoretical analysis is confirmed by experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1467-1475
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• 2001

In the present paper, approximate coordinate transformations for simulation of turbulent flows with active wall motions, leading to a significant reduction in the computational cost while maintaining the numerical accuracy, are presented: the Navier-Stokes equations are coordinate-transformed with an approximation of Taylor-series truncation and neglect of some less-significant terms. The performance of the proposed transformations is evaluated in simulation of the channel flow at Re$\sub$$\tau$/=140 with wall deformations of │η$\sub$m/$\^$+/ 5. The approximate transformations provide flow structures as wall as turbulence statistics in good agreement with those from a complete coordinate transformation [Phys. Fluids 12, 3301 (2000)] and allow 25-30% savings in the CPU time as compared to the complete one.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1160-1172
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• 2017

A novel space vector modulation strategy in the non-orthogonal three-dimensional coordinate system for multi-level three-phase four-wire inverters is proposed in this paper. This new non-orthogonal three-dimensional space vector modulation converts original trigonometric functions in the orthogonal three-dimensional space coordinate into simple algebraic operations, which greatly reduces the algorithm complexity of three-dimensional space vector modulation and preserves the independent control of the zero-sequence component. Experimental results have verified the correctness and effectiveness of the proposed three-dimensional space vector modulation in the new non-orthogonal three-dimensional coordinate system.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.4
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• pp.339-350
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• 2000

The three-dimensional new corrdinate system over a single hill double hills and complex terrain with a single hill and a rectangular obstacle was generated using a body-fitted coordinate system. Control of the coordinate line distribution in the field was executed by generalizing the elliptic generating system to Poisson equation. ▽2ξ=P. The new coordinate system was well fitted to the surface boundary of single hill and double hills. But in the case of complex terrain with hill and rectangular obstacle there was smoothing tendency around the rectangular obstacle. In order to show the validity of the body-fitted coordinate system the heat diffusion equation was transformed and the temperature distribution was calculated over the various terrain. The results showed the temperature distribution was very symmetrical and stable around hills and obstacle. As a result the couple of a body-fitted coordinate system and the heat diffusion equation were executed successfully. Wind field over complex terrain with hill and rectangular obstacle which represent urban area was simulated stably in body-fitted coordinate system. The qualitative result show the enhancement of wind speed at the upwind direction of a hill and a rectangular obstacle and the recirculation zone at the downwind direction.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.939-942
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• 1988

In order to construct a nonlinear observer, change of coordinate system is necessary. However, as in the case of feedback linearizable system it is not easy to obtain a coordinate transformation map. ln this paper, a canonical structure is proposed for observable systems with an objective of finding a vector field which is necessary for the generation of a new coordinate system.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.109-114
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• 1987

In this thesis, we work on the curve recognition with real time processing and the Robot tracking method on recognized curve. Image information of segment curve is supplied to computer to run to a Robot so that it is a feedback system. Image coordinate frame to world coordinate transformation represents in this paper and curve matching algorithm subscribes by two method, first transformation matching algorithm, second image coordinate matching algorithm. Also Robot running time to computer image processing time relationships finally includes.