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비정규지표를 이용한 Well-Conditioned 관측기 설계
정종철,허건수,Jung, Jong-Chul,Huh, Kun-Soo 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.6
In this paper, the well-conditioned observer is designed to be insensitive to the ill-conditioning factors in transient and steady-state observer performance. A condition number based on 12-norm of the eigenvector matrix of the observer matrix has been proposed on a principal index in the observer performance. For the well-conditioned observer design, the non-normality measure and the observability condition of the observer matrix are utilized. The two constraints are specified into observer gain boundary region that guarantees a small condition number and a stable observer. The observer gain selected in this region guarantees a well-conditioned and observable property. In this study, this method is applied to the Luenberger observer and Kalman filters for small order systems. In designing Kalman filters, the ratio of the process noise covariance to the measurement noise covariance is a design parameter and its effect on the condition number is investigated.
정종철,이범석,허건수,Jung, Jong-Chul,Lee, Boem-Suk,Huh, Kun-Soo 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.10
The closed-loop state and input observer is a pole-placement type observer and estimates unknown state and input variables simultaneously. Pole-placement type observers may have poor transient performance with respect to ill-conditioning factors such as unknown initial estimates, round-off error, etc. For the robust transient performance, the effects of these ill-conditioning factors must be minimized in designing observers. In this paper, the transient performance of the closed-loop state and input observer is investigated quantitatively by considering the error bounds due to ill-conditioning factors. The performance indices are selected from these error bounds and are related to the observer robustness with respect to the ill -conditioning factors. The closed-loop state and input observer with small performance indices is considered as a well-conditioned observer from the transient perspective.
박장호,홍성함,이병휘,허건수,Pak, Chang-Ho,Hong, Sung-Hahm,Lee, Byeong-Huee,Huh, Kun-Soo 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.7
In the turning process, the feed is usually selected by a machining operator considering workpiece, cutting tool and depth of cut. Even if this selection can avoid power saturation or tool breakage, it is usually conservative compared to the capacity of the machine tools and can reduce the productivity significantly. This paper proposes a selection method of the feed and the reference cutting force based on MRR(material removal rate), maximum spindle power and specific energy. In order to estimate and control cutting force accurately in transient and steady state, this study utilizes a synthesized cutting force estimation method and a Fuzzy controller. The experimental results show that these systems can be useful for the unmanned turning process.
Feedback Control for Expanding Range and Improving Lineraity of Microaccelerometers
박용화,박상준,최병두,고형호,송태용,임근원,허건수,박장현,조동일,Park, Yong-Hwa,Park, Sang-Jun,Choi, Byung-Doo,Ko, Hyoung-Ho,Song, Tae-Yong,Lim, Genu-Won,Huh, Kun-Soo,Park, Jahng-Hyon,Cho, Dong-il Institute of Control 2004 제어·로봇·시스템학회 논문지 Vol.10 No.11
This paer presents a feedback-controlled, MEMS-fabricated microaccelerometer($\mu$XL). The $\mu$XL has received much commercial attraction, but its performance is generally limited. To improve the open-loop performance, a feedback controller is designed and experimentally evaluated. The feedback controller is applied to the x/y-axis $\mu$XL fabricated by sacrificial bulk micromachining(SBM) process. Even though the resolution of the closed-loop system is slightly worse than open-loop system, the bandwidth, linearity, and bias stability are stability are significantly improved. The noise equivalent resolution of open-loop system is 0.615 mg and that of closed-loop system is 0.864 mg. The bandwidths of open-loop and closed-loop system are over 100Hz. The input range, non-linearity and bias stability are improved from $\pm10\;g\;to\;\pm18g$, from 11.1%FSO to 0.86%FSO, and from 0.221 mg to 0.128 mg by feedback control, respectively.
한상오(Sang Oh Han),김인근(In Keun Kim),허건수(Kun Soo Huh) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.12
겐트리형 리니어 모터의 주행 축은 동기화가 필수적이며 그렇지 못할 경우에는 위치의 어긋남이나 불안정한 동작으로 인해 동기오차가 발생하며 이는 고속·고정밀 선형운동에 악영향을 미친다. 또한 두 리니어 모터의 축은 로터리 모터와 달리 동력 전달장치를 제거함으로 인해 모델의 불확실성이나 외란에 민감할 뿐만 아니라 마찰과 리플의 특성에 쉽게 영향을 받는다. 본 논문은 겐트리형 리니어 모터의 주행 축을 대상으로 위치제어에 악영향을 주는 대표적인 비선형 함수인 마찰력과 리플력을 추정하여 보상하며 두 축간의 동기오차를 줄이기 위해 동기제어 알고리즘을 설계하였다. 제안된 비선형 적응제어기는 모의실험을 통하여 성능을 검증하였다. For high-speed/high-accuracy position control of a gantry-moving-type linear motor, we propose a nonlinear adaptive controller including a synchronization algorithm. Linear motors are easily affected by force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbances. Synchronization error is also caused by skew motion, model uncertainties, and force disturbance on each axis. Nonlinear effects such as friction and ripple force are estimated and compensated for. The synchronization algorithm is used to reduce the synchronous error of the two side pillars. The performance of the controller is evaluated via computer simulations.
Extended SBM 공정을 이용하여 단일 실리콘 기판상에 제작된 새로운 z축 가속도계
고형호 ( Hyoung Ho Ko ),김종팔 ( Jong Pal Kim ),박상준 ( Sang Jun Park ),곽동훈 ( Dong Hun Kwak ),송태용 ( Tae Yong Song ),조동일 ( Dong Il Cho ),허건수 ( Kun Soo Huh ),박장현 ( Jahng Hyon Park ) 한국센서학회 2004 센서학회지 Vol.13 No.2
This paper presents a novel z-axis accelerometer with perfectly aligned vertical combs fabricated using the extended sacrificial bulk micromachining (extended SBM) process. The z-axis accelerometer is fabricated using only one 1111) SOI wafer and two photo masks without wafer bonding or CMP processes as used by other research efforts that involve vertical combs. In our process, there is no misalignment in lateral gap between the upper and lower comb electrodes, because all critical dimensions including lateral gaps are defined using only one mask. The fabricated accelerometer has the structure thickness of 30 gm, the vertical offset of 12 gm, and lateral gap between electrodes of 4 gm. Torsional springs and asymmetric proof mass produce a vertical displacement when an external z-axis acceleration is applied, and capacitance change due to the vertical displacement of the comb is detected by charge-to-voltage converter. The signal-to-noise ratio of the modulated and demodulated output signal is 80 dB and 76.5 dB, respectively. The noise equivalent input acceleration resolution of the modulated and demodulated output signal is calculated to be 500 gg and 748.tg. The scale factor and linearity of the accelerometer are measured to be 1.1 mV/g and 1.18% FSO, respectively.