경사면을 주행하는 차륜형 역진자의 평형점 상태에 관한 연구

이세한(Se-Han Lee),강재관(Jae-Gwan Kang) Korean Society for Precision Engineering 2012 한국정밀공학회지 Vol.29 No.1

In this research an equilibrium point of a Wheeled Inverted Pendulum (WIP) running on an inclined road is derived and validated by some experiments. Generally, The WIP has stable and unstable equilibrium point. Only unstable equilibrium point is interested in the research. To keep the WIP on the unstable equilibrium point, the WIP is consistently controlled. A controller for the WIP needs a reference state for the equilibrium point. The reference state can be obtained by studying an equilibrium point of the WIP. This research is deriving dynamic equations of the WIP running on the inclined road and equilibrium of it based on statics. Several experiments are carried out to show the validation of the equilibrium point.

자동기립이 가능한 차륜형 역진자 시스템 개발

이세한(Se-Han Lee) 한국지능시스템학회 2015 한국지능시스템학회논문지 Vol.25 No.6

본 연구에서 자동화된 기립 및 복귀 시스템이 적용된 직립주행이 가능한 이동로봇용 구동 플랫폼이 개발되었다. 종래 대부분의 이동로봇은 정역학적으로 안정된 평면형의 4륜 혹은 3륜 구동형으로 구성되어 있는데, 이러한 형태의 이동로봇은 방향 전환을 위해서 독립구동형 혹은 조향형 차륜을 갖추고 있다. 이동로봇이 매우 협소한 지형에서 직각으로 굽은 통로를 주행할 때, 이동로봇은 전후진을 반복하는 등 복잡한 조향동작을 필요로 하거나, 극단적인 경우, 물리적인 조향이 불가능한 경우에 처하게 된다. 직립주행이 가능한 이동로봇은 점유면적이 작은 직립된 상태로 몸체의 형상을 변형시켜 해당 지형을 원활하게 통과할 수 있다. 본 연구에서 기립(복귀)동작, 확인동작, 평형제어 순으로 각 단계가 수동으로 조작되었던 기립제어 단계가 몸체의 기울기 각도 검출로 자동화되어, 단일 자동제어로 조작되는 차륜형 역진자 시스템이 제안되었다. In this study a moving platform for a mobile robot that can be traveling with a full automatic standing arm was developed. Conventional mobile robots generally may equip 4 wheels or 3 wheels with a caster wheel or independent driven wheels and have good statistic stability. When a mobile robot travels on a sharply perpendicular and narrow crossroad, it may need a special steering scheme such as going forward and backward repeatedly or it is sometimes physically impossible for the robot to go through the crossroad because of the size limit. The upright running mobile robot changes its posture to the upright posture which has a small planar area and is able to go through the crossroad. The upright control which was manually performed step by step before such as sequences of uprighting (returning), checking, and balancing, is now automated.

생물활성탄처리에 있어서 농약흡착과 칼슘축적의 영향

이세한(Se Han Lee),이순화(Shun Hwa Lee),이철희(Chul Hee Lee),박영규(Yung Kyu Park),오카다미쯔마사(Mitsumasa Okada) 大韓環境工學會 2003 대한환경공학회지 Vol.25 No.3

전자기 구동장치를 이용한 재료시험기 개발

이세한(Se-Han Lee) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.1

In this research, a material test machine is developed which uses a small electro-magnetic actuator and a leverage mechanism. The leverage mechanism amplifies the force from the electro-magnetic actuator. The electro-magnetic part operates more silently and cleanly than a hydraulic part. In a tooth material study, a test machine does not require a large force capacity because it handles only 4 mm2-sectioned and short-span specimens. Conventional test machines such as those byInstron and the BOSE Enduratec ELF3200 have too high aforce capacity for a tooth material study. A test machine for a tooth material study requires an acting force only on the order of tens of Newtons (N) operating at several Hertz.

수질관리 : 낙동강중류 수계에 있어서 APE의 오염원과 잔류특성

이세한 ( Se Han Lee ),김재광 ( Jae Kwang Kim ),신진수 ( Jin Soo Shin ),이순화 ( Shun Hwa Lee ),이철희 ( Chul Hee Lee ) 대한상하수도학회 2002 공동추계 학술발표회 논문집 Vol.2002 No.-

차륜형 역진자의 광학식 엔코더에 적용한 신경망 기반 속도추정에 관한 시뮬레이션 연구

이세한(Se-Han Lee) 한국지능시스템학회 2020 한국지능시스템학회논문지 Vol.30 No.6

광학식 엔코더는 정밀한 모터 제어에 쉽게 적용될 수 있는데, 광학식 엔코더의 출력은 디지털 펄스이며, 그 디지털 펄스는 마이크로프로세서에 쉽게 입력될 수 있다. 광학식 엔코더를 사용하는 속도추정 방법으로 T-, M-, M/T법 등 여러 가지가 존재한다. 첫 번째 2가지 방법은 매우 느린 속도에서 속도추정 성능이 측정주기에 민감하게 의존한다는 공통적인 한계점을 갖고 있다. 그 추정성능을 개선하기 위해서 테일러 급수에 기반하는 새로운 방법이 제안되었는데, 테일러 급수는 현재의 위치 데이터뿐만 아니라 과거의 여러 개의 위치 데이터를 사용하고 있다. 순수 테일러 급수는 과거의 여러 개의 데이터를 사용함에도 불구하고 구조적으로 고차 미분항 때문에 속도를 양호하게 추정하지 못하고 있다. 이 점을 극복하기 위해서, 테일러 급수와 유사한 비선형 함수를 근사할 수 있는 신경망이 제안되었다. 신경망용 학습 데이터로 실제 차륜형 역진자의 속도응답과 유사한 응답이 사용되었다. 신경망에 기반한 속도 추정은 기존의 M법에서는 곤란했던 속도응답의 흔들림을 완화하였다. An optical encoder is easily implemented for precise motor control application. The output of the optical encoder is a digital pulse form, which can make it easy to be connected to a microprocessor. There are various velocity estimation methods, T-, M-, and M/T-method by using an optical encoder. The first both methods have common limitation that the velocity estimation performance is strongly subject to estimation period in case of low velocity range. To improve the estimation performance a new method is proposed based on Taylor series which is using not only the present position data but also several ones in the past, while the M/T-method is using just present and previous sample data. Pure Taylor series cannot manage to estimate velocity well because of its having high order derivatives characteristics though it can govern a relationship among present velocity, past velocity and several past position data. To cope with it, neural network is proposed which can manage to approximate a nonlinear function resembling the Taylor series. To provide the neural network with learning data, velocity-position curve are proposed that resemble the velocity response of a real wheeled inverted pendulum. The neural network based velocity estimation can attenuate fluctuation over the velocity response while the conventional M-method cannot well.

Nd-Yag 레이저를 이용한 원통 형상 표면 마킹 시스템 개발

이세한(Se-Han Lee),강재관(Jae-Gwan Kang) 한국기계가공학회 2010 한국기계가공학회지 Vol.9 No.5

In this paper, laser marking systems dedicated to cylinderical parts was developed. We first develop the marking device which consists of Nd-Yag laser, galvano scanner and additional rotational axis, then develop algorithm for supporting the digital image with bmp data format. Additional rotational axis is so attached as to rotate the cylinderical parts for marking its whole surface. The image is separated into line by line and the separated line image is sent to galvano scanner while rotating the additional axis simultaneously. CxImage library, famous open source code, is employed for the image processing. The developed method was tested with various images and shows that it reduces marking time significantly without reducing marking quality.

경사면을 주행하는 차륜형 역진자를 위한 속도 추정기 기반 제어기 설계

이세한(Se-Han Lee),이상용(Sang-Yong Rhee) 한국지능시스템학회 2011 한국지능시스템학회논문지 Vol.21 No.3

본 논문에서는 차륜형 역진자에 적용되는 속도 추정기 기반 제어기 설계와 다양한 수치 시뮬레이션이 수행되었다. 차륜형 역진자는 불안정한 평형점과 안정한 평형점을 동시에 갖는다. 불안정한 평형점에 대하여 평형을 유지하기 위하여 차륜형 역진자는 지속적으로 제어되어야 한다. 제어기의 입력으로 차륜형 역진자 몸체의 각도, 각속도, 변위 속도 등이 필요하다. 필요한 속도는 모터에 부착된 에코더 신호를 차분하여 얻어지며, 엔코더의 해상도에 민감하게 의존한다. 저해상도 엔코더와 속도 추정기에 기반하여 개선된 속도 검출법이 제안되고 경사면에서 유효함을 보이기 위해서 다양한 수치 시뮬레이션이 수행되었다. In this research a controller based on velocity estimator for a Wheeled Inverted Pendulum (WIP) is designed and various numerical simulation studies are carried out. The WIP has stable and unstable equivalent points. To Keep the unstable equilibrium point, a controller should control carefully the wheels persistently. There are angle, angular velocity, displacement, and velocity of the WIP for controller inputs. The velocity is obtained by differentiating the encoder signals from the motor and is subject to the resolution of the encoder. An improved velocity detection method is proposed based on low resolution encoder and velocity estimator. Various numerical simulations are carried out for showing the validation of the velocity estimator in case of the inclined road condition.

정지 속도 검출 가능한 이중 증분 엔코더 센서 알고리즘 개발

이세한(Se-Han Lee),김병창(Byoung-Chang Kim) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.1

The output of the encoder is a digital pulse, which is also easy to be connected to a digital controller. There are various angular velocity detecting methods of M, T, and M/T. Each of them has its own properties. There is a common limitation that the angular velocity detection period is strongly dependent on the destination velocity magnitude in case of ultimate low range. They have ultimately long detection period or cannot even detect angular velocity at near zero velocity. This paper proposes a zero velocity detectable sensor algorithm with the dual encoder system. The sensor algorithm is able to keep detection period moderately at near zero velocity and even detect zero velocity within nominal period. It is useful for detecting velocity in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the algorithm validity.

DEVS 방법론을 적용한 소형 IoT 기기의 모니터링 시스템 모델링

이세한(Se-Han Lee),서희석(Hee-Suk Seo),최요한(Yo-Han Choi) 한국컴퓨터정보학회 2018 韓國컴퓨터情報學會論文誌 Vol.23 No.2

In this paper, we propose a Designed and Developed home router management system. Through the fourth industrial revolution and development of IoT technology, now people can experience a wide range of IoT related services at their workplace or daily lives. At the industrial site, IoT devices are used to improve productivity such as factory automation, and at home, IoT technology is used to control home appliances from a remote distance. Usually IoT device is integrated and controlled by the router. Home router connects different IoT devices together at home, however when security issues arise, it can invade personal privacy. Even though these threats exist, the perception for home router security is still insufficient. In this paper, we have designed and developed home router management system using DEVS methodology to promote the safe use of home router. Through the DEVS methodology, we have designed the system and developed the mobile application. This management system enables users to set up security options for home router easily.