Fuzzy variable structure delay control algorithms and their applications to AQM

This paper analyzes the fuzzy variable structure control algorithms for delay systems and describes the compensation mechanism of the integral factor to the effect of the delay. Based on the linearized model of the congestion-avoidance flow-control mode of transmission control protocol (TCP), we present delay control algorithms for active queue management (AQM) and discuss the parameter tuning of the algorithms. The NS (network simulator) simulation results show that the proposed control scheme for the nonlinear TCP/AQM model has good performance and robustness with respect to the uncertainties of the round-trip time (RTT) and the number of active TCP sessions. Compared to other similar schemes, our algorithms perform better in terms of packet loss ratio, throughput and butter fluctuation.

Semi-active predictive control strategy for seismically excited structures using MRF-04K dampers

The theoretical study of a semi-active predictive control(SAPC) system with magnetorheological(MR) dampers to reduce the responses of seismically excited structures was presented.The SAPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an object function,which has a function of self-compensation for time delay occurring in real application.A double-ended shear mode combined with a valve mode MR damper,named MRF-04K damper,with the maximum force of 20 kN was designed and manufactured,and parameters of the Bouc-Wen hysteresis model were determined to portray the behavior of this damper.As an example,a 5-story building frame equipped with 2 MRF-04K dampers was presented to demonstrate the performance of the proposed SAPC scheme for addressing time delay and reducing the structural responses under different earthquakes.Comparison with the uncontrolled structure,the passive-off and passive-on cases indicates that both the peak and the norm values of structural responses are all clearly reduced,and the SAPC scheme has a better performance than the two passive cases.

Observer‑Based Resilient Control of CACC Vehicle Platoon Against DoS Attack

Cooperative adaptive cruise control(CACC)is an important technology for improving road utilization and energy efficiency in the automotive industry.In CACC systems,connected vehicles can receive information from adjacent ones through com-munication networks.However,the networks are vulnerable to cyber-attacks,so the states of vehicles cannot be received promptly and accurately.This paper studies the security resilience control for a CACC system subject to denial of service(DoS)attack.The core of the proposed resilient control strategy is to estimate the delay caused by DoS attack and then compensate for it in the controller.Specifically,a CACC system is modeled by considering the impacts of DoS attack on the transmitted data.Then,a high-gain observer is presented to estimate the vehicle states including the time delay.The conver-gence of the observer is proved in a theorem based on the Lyapunov stability theory,and the high-gain-velocity observer is modified so that the estimation error of the velocity can converge to zero in a finite time.A resilient controller is designed by proposing a time delay compensation algorithm to mitigate the impacts of DoS attack.The effectiveness of the estimation and control methods is illustrated by a ten-vehicle simulation system operating at the FTP75 driving cycle conditions.And the relative estimation errors are less than 6%.