• 전기전자학회논문지
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• 제24권4호
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• pp.954-960
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• 2020

본 논문은 단상 영구자석 동기전동기의 속도 가변형 비례공진 전류제어 기법을 제안한다. 단상 영구자석 동기전동기는 전자기적 특성상 고정자 전류와 역기전력의 위상차에 따른 부토크 및 영토크가 발생하며 센서리스 운전 시 낮은 고정자 저항과 인덕턴스로 인해 과전류 제한이 필요하다. 이러한 조건하에서 전류제어를 위해 3상 교류 전동기에 사용되는 벡터 제어를 이용할 경우, 좌표변환, 역좌표변환 및 가상의 dq축 성분을 생성하는 과정이 필요하다. 하지만, 단상 영구자석 동기전동기의 자기적 특성을 고려하여 제안한 속도 가변형 비례공진 전류제어 기법은 3상 교류 전동기에 사용되는 좌표변환 과정이 필요하지 않다. 본 논문에서는 가변 비례공진 전류제어 기법을 이용하여 안정적인 기동 성능을 확인하며 일정 속도 도달 시 위치 센서 없이 단상 영구자석 동기전동기의 수학적 모델 기반 센서리스 제어로 제안한 전류제어 기법의 효용성을 다수의 실험을 통해 검증하였다.

• Journal of Welding and Joining
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• 제16권5호
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• pp.119-133
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• 1998

To implement full automation in pipe welding, it si most important to develop special sensors and their related systems which act like human operator when detecting irregular groove conditions. In this study, an automatic pipe Gas Metal Arc Welding (GMAW) system was proposed to full control pipe welding procedure with intelligent sensor systems. A five-axes manipulator was proposed for welding torch to automatically access to exact welding position when pipe size and welding angle were given. Pool status and torch position were measured by using a weld-pool image monitoring and processing technique in root-pass welding for weld seam tracking and weld pool control. To overcome the intensive arc light, pool image was captured at the instance of short circuit of welding power loop. Captured image was processed to determine weld pool shape. For weld seam tracking, the relative distance of a torch position from the pool center was calculated in the extracted pool shape to move torch just onto the groove center. To control penetration of root pas, gap was calculated in the extracted pool image, and then weld conditions were controlled for obtaining appropriate penetration. welding speed was determined with a fuzzy logic, and welding current and voltage were determined from a data base to correspond to the gap. For automatic fill-pass welding, the function of human operator of real time weld seam control can be substituted by a sensor system. In this study, an arc sensor system was proposed based on a fuzzy control logic. Using the proposed automatic system, root-pass welding of pipe which had gap variation was assured to be appropriately controlled in welding conditions and in torch position by showing sound welding result and good seam tracking capability. Fill-pass welding by the proposed system also showed very successful result by tracking along the offset welding line without any control of human operator.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.227-247
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• 2018

For intermittently connected wireless sensor networks deployed in hash environments, sensor nodes may fail due to internal or external reasons at any time. In the process of data collection and recovery, we need to speed up as much as possible so that all the sensory data can be restored by accessing as few survivors as possible. In this paper a novel redundant data storage algorithm based on minimum spanning tree and quasi-randomized matrix-QRNCDS is proposed. QRNCDS disseminates k source data packets to n sensor nodes in the network (n>k) according to the minimum spanning tree traversal mechanism. Every node stores only one encoded data packet in its storage which is the XOR result of the received source data packets in accordance with the quasi-randomized matrix theory. The algorithm adopts the minimum spanning tree traversal rule to reduce the complexity of the traversal message of the source packets. In order to solve the problem that some source packets cannot be restored if the random matrix is not full column rank, the semi-randomized network coding method is used in QRNCDS. Each source node only needs to store its own source data packet, and the storage nodes choose to receive or not. In the decoding phase, Gaussian Elimination and Belief Propagation are combined to improve the probability and efficiency of data decoding. As a result, part of the source data can be recovered in the case of semi-random matrix without full column rank. The simulation results show that QRNCDS has lower energy consumption, higher data collection efficiency, higher decoding efficiency, smaller data storage redundancy and larger network fault tolerance.

• 전자공학회논문지 IE
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• 제43권4호
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• pp.52-59
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• 2006

보행로봇은 평탄 지형에서나 비평탄 지형에서 이동할 수 있다. 지형에 따라 적절한 알고리즘으로 변화시켜 보행할 수 있다. 지금까지의 시각이 없는 로봇에 적합한 걸음새에 대한 논문들은 각 다리의 착지점을 선택하는 방법에 초점을 맞추고 있다. 그러나 본 논문에서는 스트로크와 주기를 변화시켜 비평탄 지형에서도 안정된 등속도 보행을 하는 알고리즘을 제시한다. 이 적응 알고리즘을 적용하여 로봇이 보행을 한다면, 고 기능의 센서를 이용한 복잡한 제어없이 발바닥에 장착된 힘 센서의 신호만으로도 비평탄 지형에서 안정된 등속도 보행이 가능하다. 본 논문에서는 각 다리에 2 자유도를 갖는 4족 로봇으로 평탄 지형과 비평탄 지형에서 물결 걸음새로 보행하는 실험을 하였다. 보행실험을 통하여 적응 알고리즘이 유용함을 증명하였다.

• 한국정밀공학회지
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• 제31권1호
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• pp.43-50
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• 2014

This paper introduces a robot platform which can do weeding while traveling between rice seedlings stably against irregular land surface of a paddy field. Also, an autonomous navigation technique that can track on stable state without any damage of the seedlings in the working area is proposed. Detection of the rice seedlings and avoidance knocking down by the robot platform is achieved by the sensor fusion of a laser range finder (LRF) and an inertial measurement unit (IMU). These sensors are also used to control navigating direction of the robot to keep going along the column of rice seedling consistently. Deviation of the robot direction from the rice column that is sensed by the LRF is fed back to a proportional and derivative controller to obtain stable adjustment of navigating direction and get proper returning speed of the robot to the rice column.

• 전력전자학회논문지
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• 제8권4호
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• pp.336-343
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• 2003

일반적으로 브러시리스 직류 전동기의 운전을 위한 회전자의 위치정보와 여자시점 검출을 위해서는 홀센서나 엔코더와 같은 측정 장치가 요구된다. 본 논문에서는 부가적인 검출 장치를 사용하지 않고 각 상의 단자전압을 분석하여 여자 시점뿐만 아니라 회전자의 절대위치를 검출 할 수 있는 센서리스 운전 시스템을 제안한다. 더불어, 제안한 알고리즘을 10k[W]급 전동기에 적용하여 유효성과 타당성을 검증한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.811-814
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• 1998

REcent research about current testing($\textrm{I}_{DDQ}$ testing) has been emphasizing that $\textrm{I}_{DDQ}$ testing in addition to the logical voltage testing is necessary to increase the fault coverage. The $\textrm{I}_{DDQ}$. testing can detect physical faults other than the classical stuck-at type fault, which affect reliability. One of the most critical issues in the $\textrm{I}_{DDQ}$ testing is to insert a built-in current sensor (BICS) that can detect abnormal static currents from the power supply or to the ground. This paper presents a new BICS for internal current testing for large CMOS logic circuits. The proposed BICS uses a single phase clock to minimize the hardware overhead. It detects faulty current flowing and converts it into a corresponding logic voltage level to make converts it into a corresponding logic voltage level to make it possible to use the conventional voltage testing techniqeus. By using current mirroring technique, the proposed BICS can work at very high speed. Because the proposed BICS almost does not affects normal operation of CUT(circuit under test), it can be used to a very large circuit without circuit partitioning. By altenating the operational modes, a circuit can be $\textrm{I}_{DDQ}$-tested as a kind of self-testing fashion by using the proposed BICS.

• 전력전자학회논문지
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• 제19권4호
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• pp.342-348
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• 2014

In this paper, a BLDC(Brushless DC) motor control system for driving fins to control the flight attitude of the guided artillery munition is developed. This system adopts a sensorless control scheme without any position sensor such as a Hall sensor fragile at high altitudes. The sensorless control of the BLDC motor is achieved by using commutation signals obtained from the measured pole voltages. The position control of the fin is also performed by using of the estimated speed from the commutation signals. The experimental results on the actual fin drive system demonstrated that the developed sensorless control algorithm can give an excellent position control performance.

• 디지털콘텐츠학회 논문지
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• 제16권1호
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• pp.97-104
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• 2015

기존의 1구 홀센서 방식의 수도 검침기는 역류 감지와 저속 흐름 감지가 어렵고 대기상태에서 전력 소모가 발생하는 등의 문제점을 가지고 있다. 본 논문에서는 3개의 홀센서를 $120^{\circ}$간격으로 배치해 유량의 흐름을 감지하고 유량의 방향을 검출하여 국가 기술 표준 작동연한 (8년)을 충족하는 역류 검출기능을 갖는 무선 디지털 원격 수도 검침기를 제안한다. 제안하는 검침기의 동작 알고리듬은 3개의 홀센서가 유량의 속도에 상관없이 동작하며 오차없이 유량을 카운트 하도록 구성하며 홀센서에 이벤트 발생 시 RF 모듈을 통해 지정한 주파수로 수도 검침기의 ID, 현재 시간 그리고 카운트 값을 중계기 또는 중앙 관제센터에 보내고 대기모드에서 전력이 소비되지 않게 한다.

• 대한기계학회논문집A
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• 제22권3호
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• pp.663-670
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• 1998

Most of feedback shift controllers developed in the past have fixed control parameters tuned by experts using a trial and error method. Therefore, those controllers cannot satisfy the best control performance under various driving conditions. To improve the shift quality under various driving conditions, a new self-organizing controller(SOC) that has an optimal control performance through self-learning of driving conditions and driver's pattern is designed in this study. The proposed SOC algorithm for the shift controller uses simple descent method and has less calculation time than complex fuzzy relation, thus makes real-time control passible. PCSV (Pressure Control Solenoid Valve) control current is used as a control input, and turbine speed of the torque converter is used indirectly to monitor the transient torque as a feedback signal, which is more convenient to use and economic than the torque signal measured directoly by a torque sensor. The results of computer simulations show that an apparent reduction of shift-transient torque is obtained through the process of each run without initial fuzzy rules and a good control performance in the shift-transient torque is also obtained.