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RISS 인기검색어
- 검색키워드
- 저자 : ChengJu Zhang (검색결과 3 건)
- 무료
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Neural network adaptive position tracking control of underactuated autonomous surface vehicle
ChengJu Zhang,Cong Wang,Yingjie Wei,JinQiang Wang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.2
The present study investigates the position tracking control of the underactuated autonomous surface vehicle, which is subjected to parameters uncertainties and external disturbances. In this regard, the backstepping method, neural network, dynamic surface control and the sliding mode method are employed to design an adaptive robust controller. Moreover, a Lyapunov synthesis is utilized to verify the stability of the closed-loop control system. Following innovations are highlighted in this study: (i) The derivatives of the virtual control signals are obtained through the dynamic surface control, which overcomes the computational complexities of the conventional backstepping method. (ii) The designed controller can be easily applied in practical applications with no requirement to employ the neural network and state predictors to obtain model parameters. (iii) The prediction errors are combined with position tracking errors to construct the neural network updating laws, which improves the adaptation and the tracking performance. The simulation results demonstrate the effectiveness of the proposed position tracking controller.
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Energetic walking gaits studied by a simple actuated inverted pendulum model
Kang An,Yingyuan Liu,Yiran Li,Yunxia Zhang,Chengju Liu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5
The mechanical structure and the joint torques configuration are the important parts in the biped robot design. Meanwhile, different walking speed and step length should be chosen to achieve efficient gait according to different need of walking environment. Therefore, this paper investigates the energetic walking gaits using a simple actuated inverted pendulum model. Joint torques and push-off impulse are both added in the model. The walking gaits with different joint torques configuration and with different combination of walking speeds and step lengths are analyzed. The results show that hip velocity direction is changed by the push-off impulse just before the heelstrike, which reduces the energy consumption of each step. The walking gait with minimal energy consumption is the walking pattern only with push-off, the energy cost of which is 1/4 of the walking pattern only with joint torque during the swing phase. The cost of transport (COT) and the push-off impulse of the walking gait is increasing with the increase of walking speed and step length. Using same value of push-off impulse, the walking with long step length and slow speed is more efficient. The paper can provide suggestions for designing advanced legged robot systems with high energy efficiency and various gaits. For example, the consideration of push-off mechanism can be used in the biped robots design.
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JinQiang Wang,Cong Wang,Yingjie Wei,ChengJu Zhang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6
This paper studies the three-dimensional path following control problem for an underactuated autonomous underwater vehicle in the presence of parameter uncertainties and external disturbances. Firstly, an appropriate model for the error dynamics was established to solve the path following problem in a moving Serret-Frenet frame. Secondly, an adaptive robust control scheme is proposed through fuzzy logic theory, command filtered backstepping method and an adaptation mechanism. Finally, a suitable Lyapunov candidate function is utilized to verify the stability of the overall control system and demonstrate uniform ultimate boundedness of path following errors. Following novelties are highlighted in this study: (i) The fuzzy method is adopted to solve the problems of model uncertainties, which makes the controller more practical; (ii) to calculate the virtual control derivative, a second-order filter is designed. This reduces the computational effort of the standard backstepping technique. Moreover, the effect of high frequency measurement noise is considerably attenuated via an appropriate filter to attain a more robust control system. (iii) To attain a desired approximation accuracy between the virtual control and the filtered signals, a compensation loop containing the filtered error is established. (iv) An anti-windup design is proposed to solve the problem of integral saturation in control input signals. Finally, comparative simulations are performed to ensure that the presented control scheme has excellent following accuracy and good robustness under multiple uncertainties and external disturbances.
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