摘要：For the first-order integrating processes with long delay, a Modified smith predictor (MSP) was analyzed when the control signal saturated. If the MSP controller has no anti-windup scheme, the saturation effectively chops off the control input resulting in performance deterioration. Thus, a simple and effective anti-windup scheme, without an additional parameter, is designed for the MSP. Simulation results illustrate that the proposed method may achieve good performance under the nominal and model uncertainty cases.

摘要：Active queue management(AQM)is essential to prevent the degradation of quality of service in TCP/AQM systems with round-trip time(RTT)*** delays are primarily caused by packet-propagation delays,but they can also be caused by the processing time of queuing operations and dynamically changing network *** study focuses on the design and analysis of an AQM digital controller under time-delay *** controller is based on the smith predictor algorithm and is called the smithPI *** study also demonstrates the stability of the controller and its robustness against network parameter variations such as the number of TCP connections,time delays,and user datagram protocol *** performance,robustness,and effectiveness of the proposed smithPI controller are evaluated using the NS-2 ***,the performance of the smithPI controller is compared with that of a well-known queue-based AQM,called the proportional-integral controller.

摘要：For several superior controllers of the first-order integrating processes with long delay, the windup problems are analyzed in detail when the control signal saturates. The results show that these controllers have similar characteristics about the process input limitation. And then, a simple and effective anti-windup scheme, without an additional parameter, is designed for these controllers. Simulations run with three main controllers, and the results illustrate that the proposed method may achieve good performance under the nominal and model uncertainty cases.

摘要：In order to solve the decoupling control problem of multivariable system with time delays,a new decoupling smith control method for multivariable system with time delays was proposed. Firstly,the decoupler based on the adjoint matrix of the multivariable system model with time delays was introduced,and the decoupled models were reduced to first-order plus time delay models by analyzing the amplitude-frequency and phase-frequency characteristics. Secondly,according to the closed-loop characteristic equation of smith predictor structure,proportion integration (PI) controllers were designed following the principle of pole assignment for Butterworth filter. Finally,using small-gain theorem and Nyquist stability criterion,sufficient and necessary conditions for robust stability were analyzed with multiplicative uncertainties,which could be encountered frequently in practice. The result shows that the method proposed has superiority for response speed and load disturbance rejection performance.

摘要：Feedback control is one of the most important ways to improve coiling temperature control precision during laminar cooling *** cooling equipments of a hot strip mill and structure of the control system were *** control algorithm based on PI controller and that based on smith predictor were designed and tested in a hot strip mill *** application shows that the feedback control system based on PI controller plays a limited role in improving coiling temperature control *** feedback control system based on smith predictor runs stable and *** the measured coiling temperature deviates from the target value,it can be adjusted to the required range quickly and steadily by smith predictor feedback control,which improves the coiling temperature control precision greatly,and qualities of hot rolled strips are improved significantly