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RISS 인기검색어
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- 저자 : Zhufeng Shao (검색결과 4 건)
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Liping Wang,Zhaokun Zhang,Zhufeng Shao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2
This paper presents a 3-RPaS (R and S denote the revolute and spherical joint, pa denotes the parallelogram) parallel manipulator with two-rotational-degrees-of-freedom (2R1T) and one-translational-degree-of-freedom motion. By introducing parallelograms and an innovative driving module, the 3-RPaS manipulator can change the transmission path of the driving and reaction forces, and achieves 27 actuation modes. The kinematic performance of the manipulator under different actuation modes is analyzed with the indices that are defined based on matrix orthogonal degree. Comparative analysis indicates that the kinematic performance of the manipulator varies significantly in different actuation modes. A reasonable selection of actuation modes can effectively improve the kinematic performance and eliminate singularities. The concept of optimal actuation mode and the implementation approach of actuation mode conversion are discussed and analyzed for kinematics promotion. The kinematic performance of the manipulator is greatly improved with optimal actuation modes, without changing the topology structure and dimensional parameters.
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Soheil Ganjefar,Mohammad Afshar,Mohammad Hadi Sarajch,Zhufeng Shao 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.5
In this study, a new controller method based on wavelet neural adaptive proportional plus conventional integral-derivative (WNAP+ID) controller through adaptive learning rates (ALRs) for the Internet-based bilateral teleoperation system is developed. The PID controller design suffers from dealing with a plant with an intricate dynamic model. To make an adaptive essence for PID controller, this study uses a trained offline self-recurrent wavelet neural network as a processing unit (SRWNN-PU) in parallel with conventional PID controller. The SRWNN-PU parameters are updated online using an SRWNN-identifier (SRWNNI) in order to reduce the controller error in realtime function. Using feedback linearization method and a PID controller, the presented control method reduced the tracking error in the subsystems of the teleoperation system, i.e., master and slave which are stabilized, respectively. Additionally, time-varying delay in teleoperation systems is considered as noise making the master signals be modulated because wavelt neural networks have a high susceptibility to remove the noise, thus the WNAP+ID controller is able to eliminate the noise effect. In this paper, we concentrated on the efficiency and stability of the teleoperation system with time-varying parameters through simulation outcomes. Moreover, the results of the WNNs are compared with those of multi-layer perceptron neural networks (MLPNNs).
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Lambert W Function Controller Design for Teleoperation Systems
Soheil Ganjefar,Mohammad Hadi Sarajchi,Seyed Mahmoud Hoseini,Zhufeng Shao 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.1
Stability and transparency play key roles in a bilateral teleoperation system with communication latency. This study developed a new method of controller design, based on the Lambert W function for the bilateral teleoperation through the Internet. In spite of the time-delay in the communication channel, system disturbance, and modeling errors, this approach causes the slave manipulator tracks the master appropriately. Time-delay terms in the bilateral teleoperation systems result in an infinite number of characteristic equation roots making difficulty in the analysis of systems by traditional strategies. As delay differential equations have infinite eigenspectrums, it is not possible to locate all closed-loop eigenvalue in desired positions by using classical control methods. Therefore, this study suggested a new feedback controller for assignment of eigenvalues, in compliance with Lambert W function. Lambert W function causes the rightmost eigenvalues to locate exactly in desired possible positions in the stable left hand of the imaginary axis. This control method led to a reduction in the undesirable effect of time-delay on the communication channel. The simulation results showed great closed-loop performance and better tracking in case of different time-delay types.
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Mohammad Hadi Sarajchi,Soheil Ganjefar,Seyed Mahmoud Hoseini,Zhufeng Shao 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.6
This study develops an approach of controller design, on the basis of Lambert W function structure for Internet-based bilateral teleoperation systems. Actually, time-delay terms in bilateral teleoperation systems lead to an infinite number of characteristic equation roots making difficulty in analysis of systems by classical methods. As delay differential equations (DDEs) have infinite eigenspectrums, all closed-loop eigenvalues are not feasible to locate in desired positions by using classical control methods. Therefore, this study suggests a new feedback controller for assignment of eigenvalues, in compliance with Lambert W function. In this regard, an adaptive controller is accurately employed in order to provide the controller with updated predicted time-delay and robust the system against the time-delay. This novel control approach causes the rightmost eigenvalues to locate exactly in desired positions in the stable left hand of the imaginary axis. The simulation results show strong and robust closed-loop performance and better tracking in constant and time-varying delay.
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