Optimal Control For Networked Control Systems With Long-timedelay And Packet Dropout

Networked control system is a full distribution of real-time feedback loop controlsystem that uses network to connect sensors, controllers, and actuators in differentlocations. With the development of control technology and computer communicationtechnology, as well as the network node hardware’s prices continue to decline, NCSincreasingly common used to the control field. However, as the introduction of thenetwork to the control system, the control system has a number of new features, suchas the random network-induced delay, packet loss and packet timing confusion, thesecharacteristics make analysis and control of the NCS complicate, and the traditionalcontrol algorithms can not apply to the NCS directly.This paper first studies the optimal control problem of linear NCS withlong-timedelay, design a buffer to solve the problems of the random network-induceddelay and packet timing confusion. By translate the random network-induced delayinto the fixed delay, change the optimal control problem of NCS to the controlproblem of linear systems with fixed delay. This paper gives an algorithm named stateprediction method to solve NCS optimal control problem, the algorithm uses thecurrent obtained status information and the control information of some times before,to predict the status information after a fixed delays, finally get the optimal controllaw. Then add the packet loss characteristics to the NCS with long-timedelay, byimproving the function of the buffer to solve the packet loss problem, the buffer’s newfunction is that if a packet has been lost during transmission, the buffer will send thenewest packet to controller or actuator to compensate the loss of the packet. Finally,this paper gives some simulation examples to verify the effectiveness of the stateprediction method. The paper also analyzes the feasibility of the buffer design based on embeddedLinux system. The current NCS widely use the network platform based on Linuxsystem, because Linux system is open source, it can be customized for the networknodes with different functions, it also has the features such as strong portability, safeand reliable. Using Linux network programming technology to analyze the feasibilityof the buffer design including open up space, data packets sequencing and sent onepacket every time step, the conclusion is that the design of the buffer that has thefunction of translating random time delay into fixed delay, solving packet loss andpacket timing confusion problems is entirely achievable.