• ETRI Journal
• /
• 제37권3호
• /
• pp.617-625
• /
• 2015

In this paper, a steering control system for the path tracking of autonomous vehicles is described. The steering control system consists of a path tracker and primitive driver. The path tracker generates the desired steering angle by using the look-ahead distance, vehicle heading, and a lateral offset. A method for applying an autonomous vehicle to path tracking is an advanced pure pursuit method that can reduce cutting corners, which is a weakness of the pure pursuit method. The steering controller controls the steering actuator to follow the desired steering angle. A servo motor is installed to control the steering handle, and it can transmit the steering force using a belt and pulley. We designed a steering controller that is applied to a proportional integral differential controller. However, because of a dead band, the path tracking performance and stability of autonomous vehicles are reduced. To overcome the dead band, a dead band compensator was developed. As a result of the compensator, the path tracking performance and stability are improved.

• 전자공학회논문지B
• /
• 제29B권3호
• /
• pp.25-34
• /
• 1992

This paper proposes a Self-Tuning control algorithm for tracking the reference trajectory by measuring the end-point of robot manipulator whose links are light and flexible, and the performance of it is tested through the computer simulation. As an object of system, a flexible robot manipulator with two-links is considered and an assumed mode shape method including gravity force is adopted to analyze the vibration modes for each links and dynamics equation is derived. The controller is designed as a combined form which consists of dynamic feedforward compensator and self-tuning feedback controller. The one supplies nominal torque and the other supplies variational torque to manipulator. Apart from the, K-incremental predictor is also proposed in order to eliminate the offset error. and it shows that the result of simulation adapted well to load change and rapid velocity.

• 천문학논총
• /
• 제11권1호
• /
• pp.147-161
• /
• 1996

The development of universal CCD camera control software for all BOAO CCD camera systems is proposed. The new software, running under Sun SPARCstation and motif based X window system with SunOS 4.1.3 operating system, replaces existing control software based on NeXTstation color and NeXTstep 2.1 operating system which is no more produced now. Several new features of the new software is introduced, some of which are 1) the image contrast is enhanced by color manipulation and display, 2) image zooming and trimming, 3) any size of image can be displayed in the scrolled window, and 4) the offset between telescope pointing position and CCD center is easily calculated by alt-azi map. Along with the above new features, the new software has advantages including ease of maintenance and upgrading and elimination of risk caused by hardware damage. Since September 1, the software beta version is being used by observers and there is not seen severe problem regarding the software itself, but several requests to equip more features to the software will be mirrored to future release.

• 반도체디스플레이기술학회지
• /
• 제14권4호
• /
• pp.72-77
• /
• 2015

Three-level diode clamped multilevel inverter, generally known as neutral point clamped (NPC) inverter, has an inherent problem causing neutral point (NP) potential variation. Until now, the NP potential problem of variation has been investigated and lots of solutions have also been proposed. This paper presents a neutral point voltage control technology using the anti-windup PI controller and offset technology of PWM (Pulse Width Modulation) to control the variation of NPC 3-phase three-level inverter neutral point voltage. And the proposed algorithm is tested and verified using a PLL (Phase Locked Loop) in order to synchronize the phase voltage from the line voltage of grid. It significantly improves the voltage balancing under a solar fluctuation conditions of the inverter. Experimental results show the good performance and effectiveness of the proposed method.

• 대한기계학회논문집
• /
• 제13권3호
• /
• pp.443-450
• /
• 1989

본 연구에서는 공작기계 생산 현장에서 직접적으로 이용될 수 있는 측정시스 템의 개발을 목표로 이제까지 이론적으로 제안된 스핀들 정밀도 측정방법을 종합 분석 하여 디지틀 측정의 기본이론을 정립하고 이를 기반으로 마이크로 컴퓨터를 이용한 측정시스템을 실계 제작하였다.또한 실험을 통하여 본 연구에서 제안된 측정 시스 템의 성능을 기존의 애널로그 측정방법과 비교 검토함으로써 본 방법의 우수성 및 제한점을 실증적으로 입증하고자 하였다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2017년도 전력전자학술대회
• /
• pp.235-236
• /
• 2017

본 논문에서는 저압 직류 배전 시스템에 사용되는 3-레벨 NPC DAB 컨버터의 중성점 전압 제어를 위한 향상된 스위칭 알고리즘을 제안한다. 3-레벨 NPC DAB 컨버터는 구조상 정격전압 감소를 위해 중성점을 기준으로 DC-link 단에 두 개의 캐패시터가 사용되기 때문에 중성점으로 들어오는 전류에 불균형이 발생하며 중성점 전압이 흔들리는 문제점이 나타난다. 중성점 전압이 흔들릴 경우 불균형한 전압이 변압기에 형성되며 이로 인해 전류 Offset과 실효 전류의 증가에 따른 전력 손실증가 등 전체적인 컨버터의 동작에 악영향을 준다. 따라서 본 논문에서는 3-레벨 NPC DAB 컨버터의 동작원리 및 기존 스위칭 패턴을 분석하고, 향상된 스위칭 패턴을 적용시켜 중성점 전압을 제어하는 알고리즘의 타당성을 모의시험을 통해 검증하고자 한다.

• 한국군사과학기술학회지
• /
• 제14권6호
• /
• pp.1043-1048
• /
• 2011

In this paper, a newsynchronization technique applied to burst-mode communication is proposed. A synchronization technique is to estimate carrier frequency and phase offsets in a noisy channel environment. A fundamental problem for estimating the parameters(carrier phase and frequency offsets) in burst-mode transmission is that the ways of pursuing estimation accuracy and transmission efficiency are always trade-off. To solve this problem, a new carrier recovery technique is proposed to improve the transmission efficiency with reliable performance especially at low S/N. In the proposed technique, the synchronization parameters are first estimated based on a data-aided feed-forward estimation scheme. Then, a phase tracker using decision-directed DPLL estimates the phase offset for the data portion of the burst data. From simulation results, it shows fast synchronization with shorter preamble maintaining reasonable BER performance at low S/N.

• Journal of Power Electronics
• /
• 제13권6호
• /
• pp.1042-1050
• /
• 2013

This paper presents a study of maximum power point tracking (MPPT) for photovoltaic arrays with only one current sensor. Initially, a review of MPPT methods with only a current sensor is performed with extension for a variety of dc/dc converters. Furthermore, the same topology is developed to achieve better performance in the presence of sensor offset and environmental noise. The proposed method is robust, cost effective, and behaves well dynamically and in the steady state. After a theoretical analysis of presented approach, its validity and effectiveness are verified by simulation and experimental results.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2014년도 전력전자학술대회 논문집
• /
• pp.69-70
• /
• 2014

In this paper, the 50kw submerged arc welding system has AC/DC durable output power and when AC output power is on, it shows control function on frequency, duty and offset. This system is constructed based on parrallel system, set on modular structure minimize the influence from high power into system. Also, it applied the sequence for optimized welding ability which lead it to increased weld quality.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 A
• /
• pp.391-393
• /
• 1995

An improved predictive control technique using adaptive load estimation is proposed. The conventional predictive control technique has not concerned load variations and system parameters. Thus control performances are undesirable such as large current ripples and offset. In this paper the proposed controller employing a simple adaptive algorithm to estimate load is expected to be useful to overcome the problems of conventinal predictive controller.