• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1071-1078
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• 2018

In this paper, we implemented community driving system for auto-vehicles as a preceding research of drone's community flight. We used ultrasonic sensors in order to measure the distance between vehicles, and designed each vehicles to maintain specific distance to each other, by making the following vehicle to stop moving when the distance is closed to less than 20cm, to start moving when the distance increases to more than 30cm. We have also designed vehicle to accelerate until the distance is closed to 30cm when they are apart for more than 40cm due to contingencies during driving.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.276-282
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• 2006

PID controller has been widely used in industry. Because it has a simple structure and robustness to modeling error. But it is difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose an adaptive PID controller based on a gradient descent learning. This algorithm has a simple structure like conventional PID controller and a robustness to system parameters variation and different velocity command. To verify performances of the proposed adaptive PID controller, the speed control of nonlinear DC motor is performed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.289-292
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• 2005

PID controllers, which have been widely used in industry, have a simple structure and robustness to modeling error. But it is difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose an adaptive PID controller based on a gradient descent learning. This algorithm has a simple structure like conventional PID controller and robustness to system parameters variation. To verify performances of the proposed adaptive PID controller, the speed control of nonlinear DC motor is performed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.25-28
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• 2002

본 논문은 마이크로 프로세스로 처리되는 여러 제어장치들 중에서 PI제어기의 최적 자동동조에 관한 개선된 방법을 제안하고자 한다. 이 방법은 Relay 자동동조 법으로서 이를 마이크로 프로세스에 응용하여 제어대상에 최적의 PI계수를 입력하게된다. 이를 위해 먼저 Computer와 DSP사이에 통신이 가능하도록 RS-232를 설치하고, 컴퓨터의 제어신호에 따라 모터의 속도가 Relay와 PI제어기에 의해 목표값에 도달할 수 있도록 설계하였다. 내부적으로 사용된 Relay 동조방식은 Relay로 제어대상의 출력을 강제로 진등시켜서 출력의 진폭과 주기를 이용하여 PI 계수를 조정하고 제어기의 입력값으로 선택된다. Relay동조 법은 동조과정이 간단하여 동조 방식의 구현이 쉽다. 또 위상여유를 고려하여 제어기의 계수를 조정하기 때문에 시스템의 견실성을 향상시킬 수 있을 뿐 아니라, 비례 제어만으로 임계 진동을 하지 않는 시스템의 경우에도 사용할 수 있고, 원점에 극점이 있는 경우에도 적용할 수 있어서 기존의 제어방식이 가지는 제약성의 한계를 극복할 수 있어서 적용성이 우수하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.829-832
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• 2004

실제영상으로 가상환경을 구축해서 사용자가 가상환경을 돌아다님으로써 보다 큰 몰입감과 현실감을 제공하는 영상기반 가상현실 기술은 최근 들어 웹 기반 가상현실시스템을 구축하기 위해서 많이 사용된다. 이 기술은 가상환경 구축에 있어 항해를 쉽게 하기 위한 한 방법으로 넓은 시각 영역(field of view)을 얻을 수 있는 wide-angle 렌즈를 흔히 사용한다. 어안렌즈(fish-eye lens)는 전형적인 넓은 시각 영역을 가진 렌즈로서, 매우 큰 radial distortion 을 가진다. 왜곡을 없앤 영상을 얻기 위해 본 논문에서는 구면기하(spherical geometry) 및 사영기하(projective geometry)를 사용하여 어안영상을 보정하는 non-metric기법을 제안한다. 제안한 이 방법은, 기존의 방법들 보다는 쉽고 빠른 속도로 왜곡을 보정할 수 있으므로 어안영상의 왜곡을 보정하는 하드웨어를 효율적으로 구현할 수 있다. 그리고 spheroid 를 이용해 좀 더 왜곡을 정확히 보정방법과 별도의 서보 모터 없이 pan/title 를 가능케 하는 시점이동에 따른 왜곡 보정 방법을 제시한다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.209-212
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• 2000

This paper describes the design and implementation of a hard- wired AGV controller using CPLD(Complex Programmable Logic Device). The proposed controller manages a guidance equipment, motor and I/O sequence controller for a self-control traveling. Compared with a conventional $\mu$-processor, the CPLD controller using a hard-wired control method can reduce a difficult programming process. Also, the total costs of production are reduced, such as development time, product's size and difficulty because memory, combinational logic and sequential logics are implemented by CPLD. The Controller designed using behavioral description method with VHDL and was synthesized by MAX＋Plus II of the ALTERA co. We implemented controller using EPF10K10LC84-4 device.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.1071-1074
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• 2015

본 논문은 진공을 이용한 흡착방식과 바퀴형 이동방식을 이용하고 환경 탐지용 센서를 부착한 벽면 이동형 로봇의 물리적 해석을 통한 이동 성능 개선에 관한 연구로서, 대형 구조물의 안전 검사 및 위험한 시설물의 보수 작업등을 보조하기 위한 목적이 있다. 로봇의 무게에 따른 중력을 견딜 수 있는 강력한 진공흡착방식과 고성능 모터 제어에 의한 바퀴 이동방식을 혼합하고 효율적으로 평형을 유지 또는 제어하기 위하여 로봇에 미치는 다양한 힘과 모멘트를 분석하고 수식화 하였으며 기존의 수직이동 속도를 개선하기 위한 로봇의 물리적 변수를 추출하여 변수와 이동력간의 관계를 고찰하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.60-66
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• 2019

In this report, the process characteristic(viscosity), mechanical properties, combustion characteristics, ground and flight test results of propellants used for a rocket-assisted projectile are described according to several aluminum contents. As the aluminum content increased, initial viscosity decreased, viscosity build-up accelerated, and combustion rate and pressure exponent decreased. In the ground fire test, the total impulse of the rocket-assisted projectiles containing 10 wt% of aluminum were 5% higher than that of the rocket-assisted projectiles containing 2 wt% and 18 wt% of aluminum. The motor efficiency compared to the theoretical performance was 85.6% with 18 wt% of aluminum, the lowest value among the propellant compositions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.668-669
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• 2016

The retarder as a hydraulic brake system in order to assist a service brakes in commercial vehicle is operated by automatic and manual mode due to driver. Braking energy by retarder operation is transmitted to the engine radiator of vehicle cooling system, passing through the retarder oil heat exchanger. At this moment, the retarder ECU performs the function that is controlled a braking torque with consideration for automatic and manual mode, temperature of retarder oil/water, engine coolant temperature, vehicle speed, and etc. In this paper, it deals with the design of retarder control logic and the results of retarder braking performance test regarding a cooling system of retarder and vehicle.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.37-44
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• 2021

This study is implemented as a sensor-less position controller capable of multi-turn detection to replace the expensive absolute encoder used in the turret servo system. For sensor-less control, the position information of the rotor is essential. For this, a magnetic flux estimator was implemented from the mathematical model of IPMSM used in the turret servo system. The position of the rotor and the angular velocity of the rotor were obtained using the rotor magnetic flux calculated from the magnetic flux estimator. Using the zero-crossing technique, one pulse was generated for each rotation of the estimated rotor magnetic flux to measure the number of multi-turns. Simulation and experiment results confirmed the usefulness of the proposed method.