Browsing by Author "Hsieh, Chen-Chou"

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Analysis and applications of the motion message estimator for network control systems
(2008-01-01)
Hsieh, Chen-Chou
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Hsu, Pau-Lo
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電控工程研究所
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Institute of Electrical and Control Engineering
The time-delay effect in network systems is unavoidable because of its limited transmission bandwidth. In real-time network control systems (NCS), all messages are required to be transmitted or received to meet specifications of the deadline. Therefore, the data dropout may thus occur in NCS due to its time delay in a stochastic nature. In this paper, a motion message estimator is proposed to construct a real-time motion NCS to significantly reduce the data-dropout effect. Both simulation and experimental results indicate that a 3rd-order message estimator based on the Taylor expansion can be properly implemented in NCS for industrial motion control systems. Furthermore, since the uncertainties of the NCS estimator are greatly suppressed by applying the message, experimental results indicate that its integration with the feedforward control leads to significantly improved accuracy for the NCS implemented on an industrial computerized numerical control (CNC) machine tool.
Switched Message Estimation for Time-varied Data Dropout in Networked Control Systems
(2014)
Hsieh, Chen-Chou
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Hsu, Pau-Lo
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
As messages and nodes over a network increase, delay time in a networked control system (NCS) increases and results in frequent dropout, thereby seriously degrading the performance and stability of NCS. Therefore, effective methods are urgently needed to handle the time delay and dropout effects of NCS. In this paper, a real-time transition probability estimator for the two-state Markov chain model is proposed for online monitoring of the dropout condition by using a short-window technique. Furthermore, under time-varied dropout conditions, the most suitable least-square estimator can be determined in real time by applying intelligent message estimator (IME), and missing data from NCS can be efficiently estimated and restored.
The motion message estimator in real-time network control systems
(2006)
Hsieh, Chen-Chou
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Hsu, Pau-Lo
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Wang, Bor-Chyun
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電控工程研究所
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Institute of Electrical and Control Engineering
In network systems, the time-delay effect is unavoidable and it usually degrades system performance. Furthermore, in the real-time network control system (NCS), messages are required to be transmitted on time to meet specifications of the deadline. Otherwise, it leads to data dropout which occurs randomly in real-time NCS control. The data dropout not only degrades performance of the NCS but also causes the NCS to be unstable. In this paper, a second-order motion message estimator is proposed to compensate for the missing messages containing motion commands and measurements, since most motion systems can be described suitably by second-order Newtonian motion law. The dropout rate of the controller area network (CAN) bus has been evaluated in different transmission rate in this paper. The proposed NCS with the message estimator has been successfully implemented on a CNC machine to achieve significantly improved motion accuracy.
The SDQ-based Message Estimator for Motion NCS
(2009)
Hsieh, Chen-Chou
;
Hsu, Pau-Lo
;
Wang, Bor-Chyun
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The limitation of network bandwidth leads to data dropout of communication which degrades performance of NCS. For motion control system implemented with NCS, the missing interpolation messages will cause motion error and it can be compensated by applying the message estimator. However, the distribution of the missing data will be more relevant to motion accuracy in NCS even with the same dropout rate. This paper proposes a novel performance index, the short-window dropout quantities (SDQ) which is an estimation of both the data dropout rate and the messing message distribution, for the motion NCS. Furthermore, based on the estimation of SDQ. the intelligent motion message estimator (IMM) is proposed in this paper to effectively compensate for data dropout effect. Finally, simulation results of a multi-axis motion NCS indicate that the present IMM significantly improves motion contouring accuracy compared with the 1-delay estimator or the Taylor estimator.