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.
- motion message estimator; data-dropout; NCS; feedforward control