Tracking Performance Limitation Of Networked Control Systems Based On Packet Dropouts Constraint

The introduction of network into the control system has become a hot spot for the last few years.Networked control system(NCSs)is the structure to use the private or public computer communication network controller to replace the traditional point to point in order to achieve the system of sensors,controllers and control information between the system components such as mutual transfer.While NCSs bring convenience to the life,they have also risen to new challenges due to the packet dropouts,time delay,bandwidth,channel noise,quantization,channel input power constraint and so on.In this paper,these constraints are called communication parameter constraints.Based on these communication parameter constraints,the tracking performance limitation of NCSs will be greatly affected.In this paper,the problem of the tracking performance limitation based on communication parameters is mainly studied.The main research contents are as follows:The tracking performance limitation of NCSs with quantization constraint in the forward channel and packet dropouts constraint in the feedback channel is considered.The obtain result shown that the tracking performance limitation depends on the non-minimum phase zeros position,unstable poles position of a given plant,quantization interval and packet dropouts probability.The result also shows how the quantization interval and packet dropouts probability may fundamentally constrain the tracking capability of NCSs.In the practical application of NCSs,the tracking performance limitation will tend to infinity if the plant dose not contain an integrator.In this case,the definition of the previous tracking performance index is not applicable.Therefore,a new method is required to characterize the tracking ability.In addition,for the given plant,the existence of delay,packet dropouts and the channel input energy will have a great impact in the tracking performance limitation.Therefore,it is necessary to study the modified tracking performance limitation of networked time-delay systems with packet dropouts and channel input energy constraints.The obtained results show that the modified tracking performance limitation is related to the intrinsic properties of a given plant such as non-minimum phase(NMP)zeros position,unstable poles position and time-delay.Furthermore,the modified factor and packet dropout probability affect the modified tracking performance limitation of the networked time-delay systems.The modified tracking performance limitation with the channel input power constraint is obtained by searching through all stabilizing one-parameter compensators.In practical application,the bandwidth in a communication cannot be infinite.The tracking performance will be greatly affected when the bandwidth and packet dropouts constraints exit simultaneously in the communication channel.Then based on bandwidth and packet dropouts constraint,study the modified tracking performance limitation of NCSs.The obtained results show that the modified tracking performance limitation is related to the intrinsic properties of a given plant such as non-minimum phase zeros position,unstable poles position,and their directions.Furthermore,the modified factor,packet dropouts probability and bandwidth also impact the modified tracking performance limitation of the NCSs.The modified tracking performance limitation with channel input power constraint is obtained by searching through all stabilizing two-parameter compensator.The above research results will provide a good theoretical guidance for the design and application of NCSs in the future.