Min-Max Model Predictive Controller for Trajectory Tracking of a Wheeled Mobile Robot with Slipping Effects

GAO, Yu,CHONG, Kil To The Institute of Electronics, Information and Comm 2011 IEICE transactions on fundamentals of electronics, Vol.ea94 No.2

<P>A min-max model predictive controller is developed in this paper for tracking control of wheeled mobile robots (WMRs) subject to the violation of nonholonomic constraints in an environment without obstacles. The problem is simplified by neglecting the vehicle dynamics and considering only the steering system. The linearized tracking-error kinematic model with the presence of uncertain disturbances is formed in the frame of the robot. And then, the control policy is derived from the worst-case optimization of a quadratic cost function, which penalizes the tracking error and control variables in each sampling time over a finite horizon. As a result, the input sequence must be feasible for all possible disturbance realizations. The performance of the control algorithm is verified via the computer simulations with a predefined trajectory and is compared to a common discrete-time sliding mode control law. The result shows that the proposed method has a better tracking performance and convergence.</P>

Tracking control for wheeled mobile robots with slipping effects

Yu Gao(고유),Kil To Chong(정길도) 대한전자공학회 2010 대한전자공학회 학술대회 Vol.2010 No.6

Tracking control of wheeled mobile robot using a receding horizon controller with time-delay

Yu Gao,Kil To Chong(정길도) 제어로봇시스템학회 2008 제어로봇시스템학회 국내학술대회 논문집 Vol.2008 No.10

In this study, a receding horizon (RH) controller is developed for the tracking control of wheeled mobile robots (WMRs) subject to nonholonomic constraints in environments without obstacles. The tracking-error kinematic model is first linearized at the equilibrium point. Then, it is transformed into an exact discrete form considering the time-delay. The control policy is derived from the optimization of a quadratic cost function, which penalizes the tracking error and control variables in each sampling time. The minimization problem is solved by using the OP (Quadratic Programming) method taking the current error state as the initial value and including the input constraints, which include the velocity and acceleration constraints to prevent the mobile robot from slipping. The performance of the control algorithm is verified via computer simulations with predefined trajectory showing that the strategy is feasible.

The Influence of Managerial Overconfidence on Earnings Management

Gao, Yu(고우),Han, Kil-Seok(한길석) 한국경영교육학회 2018 경영교육연구 Vol.33 No.3

[연구목적] 본 연구의 목적은 2009년부터 2017년까지 코스피 시장과 코스닥 시장에 상장된 기업을 대상으로 경영자의 과신성향이 이익조정에 미치는 영향을 검증하고자 하였다. [연구방법] 본 연구에서 경영자 과신은 자산 성장률을 종속변수로 하고 매출액성장율을 독립변수로 하여 산업-연도별 회귀분석을 수행한 후 잔차를 추출하여 측정하였다. 또한 이익조정측정치는 수정된 Jones모형과 Kothari모형과 Roychowdhury모형과 Cohen모형을 활용하여 각각 추출하였다. 이를 토대로 경영자 과신과 이익조정과의 관계를 분석하였다. [연구결과] 실증분석 결과는 경영자 과신성향이 이익조정에 유의적인 관계를 보이고 있어 경영자 과신성향이 이익조정에 영향을 미치고 있는 것으로 나타났다. [연구의 시사점] 본 연구의 분석결과에서 경영자가 과신성향을 갖는 경우 경영자의 이익조정이 높다는 것을 보임으로써 경영자의 성향은 이익조정에 관한 의사결정에 있어 고려해야 할 요소로 나타났다. 본 연구는 최근 행동경제에 관한 많은 연구가 진행되고 있으나 회계분야의 연구에서는 아직 초기 단계라 할 수 있는 경영자의 비합리적 행동인 경영자 과신과 이익조정과의 관계를 분석하였다는 점에 의의가 있다. [Purpose] The purpose of this study is to investigate the influence of managerial overconfidence on earnings management. [Methodology] We use a measure of managerial overconfidence from investment level-based measure. We measure earnings management four ways including the modified Jones model (Dechow et al., 1995), performance matched discretionary accrual model (Kothrai et al., 2005), Roychowdury model (Roychowdury, 2006) and Cohen model (Cohen et al., 2008). We employ OLS model to test the association between managerial overconfidence and earnings management. [Findings] We find that managerial overconfidence significantly and positively influence accrual earnings management and real earnings management respectively. [Implications] While there are many researches on earnings management motivation we employ behavioral finance research and explore earnings management from the irrational behavior dimension unlike the prior literature.

The Effect of Managerial Overconfidence on Firm Value

Gao Yu(고우),Kim, Neung-sup(김능섭),Han, Kil-Seok(한길석) 한국경영교육학회 2018 한국경영교육학회 학술발표대회논문집 Vol.2018 No.11

Rapamycin Inhibits Transforming Growth Factor β1-Induced Fibrogenesis in Primary Human Lung Fibroblasts

Yu Gao,Xuefeng Xu,Yan Liang,Dianhua Jiang,Huaping Dai 연세대학교의과대학 2013 Yonsei medical journal Vol.54 No.2

Purpose: The present study was designed to determine whether rapamycin could inhibit transforming growth factor β1 (TGF-β1)-induced fibrogenesis in primary lung fibroblasts, and whether the effect of inhibition would occur through the mammalian target of rapamycin (mTOR) and its downstream p70S6K pathway. Materials and Methods: Primary normal human lung fibroblasts were obtained from histological normal lung tissue of 3 patients with primary spontaneous pneumothorax. Growth arrested, synchronized fibroblasts were treated with TGF-β1 (10 ng/mL) and different concentrations of rapamycin (0.01, 0.1, 1, 10 ng/mL) for 24 h. We assessed m-TOR, p-mTOR, S6K1, p-S6K1 by Western blot analysis, detected type III collagen and fibronectin secreting by ELISA assay, and determined type III collagen and fibronectin mRNA levels by real-time PCR assay. Results: Rapamycin significantly reduced TGF-β1-induced type III collagen and fibronectin levels, as well as type III collagen and fibronectin mRNA levels. Furthermore, we also found that TGF-β1-induced mTOR and p70S6K phosphorylation were significantly down-regulated by rapamycin. The mTOR/p70S6K pathway was activated through the TGF-β1-mediated fibrogenic response in primary human lung fibroblasts. Conclusion: These results indicate that rapamycin effectively suppresses TGF-β1-induced type III collagen and fibronectin levels in primary human lung fibroblasts partly through the mTOR/p70S6K pathway. Rapamycin has a potential value in the treatment of pulmonary fibrosis.

Model predictive controller for trajectory tracking of wheeled mobile robots with slipping effects

Yu Gao,Kil To Chong 제어로봇시스템학회 2009 제어로봇시스템학회 합동학술대회 논문집 Vol.2009 No.12

Receding horizon tracking control for wheeled mobile robots with time-delay

Yu Gao,이창구,정길도 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.12

In this paper, a receding horizon (RH) controller is developed for tracking control of wheeled mobile robots (WMRs) subject to nonholonomic constraint in the environments without obstacles. The problem is simplified by neglecting the vehicle dynamics and considering only the steering system. First, the tracking-error kinematic model is linearized at the equilibrium point. And then, it is transferred to an exact discrete form considering the time-delay. The control policy is derived from the optimization of a quadratic cost function, which penalizes the tracking error and control variables in each sampling time. The minimizing problem is solved by using the QP (quadratic programming) method taking the current error state as the initial value and including the velocity constraints. The performance of the control algorithm is verified via the computer simulations with several different predefined trajectories showing that the strategy is feasible.

Name and Maintain Topological Faces in Rotating and Scanning Features

Gao Xue-Yao,Li Jia-Qi,Guo Hao,Gao Yun-Feng,Liu Yu-Hong 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.3

Features created in rotating and scanning operations are very complex. Naming and identifying their topological faces is an important problem in CAD fields. In this paper, a new method of coding topological faces in rotating and scanning features is proposed. Firstly, contour segments are numbered. Secondly, an angle between contour segment and rotating axis is computed. Thirdly, all topological faces are named based on contour segments’ numbers, rotating axis and other information. When a face splits and several subfaces merge, a method of processing their codes is given. The proposed method is applied to HUST-CAID feature modeling system. Experimental results show that it can name and identify topological faces effectively in operations.

Structural transformation, spectroscopic characterization and magnetic properties of La1xGdxCoO3

Yu Gao,Hong Chang,Qiang Wu,P. Suresh Kumar,Meiling Li,Fang Liu,Hongjing Zhu,Yanbo Pang,Yuehou Yun 한국물리학회 2016 Current Applied Physics Vol.16 No.8

La1xGdxCoO3 for x < 0.2 crystallize in the rhombohedral structure, and it is orthorhombic for x 0:2. The lattice volume systematically decreases as x increases. The analysis of the Co 2p3/2 xps spectra indicates that the Co ions are at both þ3 and þ8/3 valence states, and the calculated oxygen content is about 2.93 per formula unit. The bending vibration of the CoeO bond linearly shifts from 429 cm1 to 482 cm1 with the increasing x, and it is coincident with the increasing CoeOeCo angle. The shoulder peak at approximately 575 cm1 becomes obviously wide with the increasing doping Gd3þ content owing to the magnetic interactions of the Gd3þ ions with the surrounding CoO6 octahedra. The energy band gap slightly increases from about 2.40 eV to about 2.75 eV as the structure transforms from the rhombohedral to the orthorhombic structure. The magnetic properties are ferrimagnetic with x ¼ 0.05, 0.3 and 0.7. However, the calculated Curie-Weiss temperature and constant of La0.3Gd0.7CoO3 are not reasonable, it is probably due to a nonlocalized electronic state.