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RISS 인기검색어
- 검색키워드
- 저자 : Changjun Zhao (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Balancing control of Mobile Manipulator with Sliding mode Controller
Yudong Zhao,Changjun Woo,Jangmyung Lee 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
This paper proposes an attitude control system to keep the balance of a two-wheeled mobile manipulator which consists of a mobile platform and a three D.O.F. manipulator. In the conventional control scheme, complicated dynamics is utilized for balancing control of a mobile manipulator. In this paper, however, three links are considered as one body and the dynamics is derived easily by using inverted pendulum model. sliding mode controller is characterized as low sensitivity to plant parameter uncertainties and disturbances and non-necessity of an explicit model of the system. Therefore, it is adopted in this research for the attitude control of mobile platform with respect to the pitch axis. The center of gravity for the whole mobile manipulator is changing along with the motion of the manipulator. And the orientation variation of center of gravity is used as reference input for the sliding mode controller to maintain the center of gravity in the middle of robot so that the whole system can keep balance. To confirm the performance of the controller proposed in this paper, MATLAB Simulink has been used and an experiment is carried out to demonstrate the superiority of the proposed attitude control.
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Analysis of Switching Clamped Oscillations of SiC MOSFETs
Ke, Junji,Zhao, Zhibin,Xie, Zongkui,Wei, Changjun,Cui, Xiang The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
SiC MOSFETs have been used to improve system efficiency in high frequency converters due to their extremely high switching speed. However, this can result in undesirable parasitic oscillations in practical systems. In this paper, models of the key components are introduced first. Then, theoretical formulas are derived to calculate the switching oscillation frequencies after full turn-on and turn-off in clamped inductive circuits. Analysis indicates that the turn-on oscillation frequency depends on the power loop parasitic inductance and parasitic capacitances of the freewheeling diode and load inductor. On the other hand, the turn-off oscillation frequency is found to be determined by the output parasitic capacitance of the SiC MOSFET and power loop parasitic inductance. Moreover, the shifting regularity of the turn-off maximum peak voltage with a varying switching speed is investigated on the basis of time domain simulation. The distortion of the turn-on current is theoretically analyzed. Finally, experimental results verifying the above calculations and analyses are presented.
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An investigation on the bearing capacity of steel girder-concrete abutment joints
Chen Liang,Yuqing Liu,Changjun Zhao,Bo Lei,Jieliang Wu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.3
To achieve a rational detail of the girder-abutment joints in composite integral bridges, and validate the performance of the joints with perfobond connectors, this paper proposes two innovative types of I-shaped steel girder-concrete abutment joints with perfobond connectors intended for the most of bearing capacity and the convenience of concrete pouring. The major difference between the two joints is the presence of the top flange inside the abutments. Two scaled models were investigated with tests and finite element method, and the damage mechanism was revealed. Results show that the joints meet design requirements no matter the top flange exists or not. Compared to the joint without top flange, the initial stiffness of the one with top flange is higher by 7%, and the strength is higher by 50%. The moment decreases linearly in both types of the joints. At design loads, perfobond connectors take about 70% and 50% of the external moment with and without top flange respectively, while at ultimate loads, perfobond connectors take 53% and 26% of the external moment respectively. The ultimate strengths of the reduced sections are suggested to be taken as the bending strengths of the joints.
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Analysis of Switching Clamped Oscillations of SiC MOSFETs
Junji Ke,Zhibin Zhao,Zongkui Xie,Changjun Wei,Xiang Cui 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
SiC MOSFETs have been used to improve system efficiency in high frequency converters due to their extremely high switching speed. However, this can result in undesirable parasitic oscillations in practical systems. In this paper, models of the key components are introduced first. Then, theoretical formulas are derived to calculate the switching oscillation frequencies after full turn-on and turn-off in clamped inductive circuits. Analysis indicates that the turn-on oscillation frequency depends on the power loop parasitic inductance and parasitic capacitances of the freewheeling diode and load inductor. On the other hand, the turn-off oscillation frequency is found to be determined by the output parasitic capacitance of the SiC MOSFET and power loop parasitic inductance. Moreover, the shifting regularity of the turn-off maximum peak voltage with a varying switching speed is investigated on the basis of time domain simulation. The distortion of the turn-on current is theoretically analyzed. Finally, experimental results verifying the above calculations and analyses are presented.
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