Variable Sampling Period Network System Of Collaborative Design And Simulation Research

With the industrial control system is becoming more and more complex, the control systems requirement to achieve network. Therefore, the network control system is the inevitable trend in the control field. Networked control system is a kind of networked, real-time feedback control system with fully distributed. It has a large number of advantages, such as less wiring, wide control range, easy to extend, but because of each node shared communication channel in the network, inevitable bring some networked problems such as network induce delay and data packet conflict, this series of network problems are particularly prominent especially in the large network load and the complex network environment. The control performance of network control system is influenced by the quality of performance and quality of service. Sampling period is an important link connection control performance and network utilization. Ever the control methods are adopted fixed sampling is not only a waste of network source, but also can not meet the practical situations that the different types controlled object has different change rate of parameters in circuits. This paper is based on sampling period, with variable sampling period scheduling strategy on the network systems; dynamically adjust the sampling period of each subsystem, so as to realize the collaborative design of control and scheduling in network control system. This paper mainly based on control and scheduling co-design as the breakthrough point of the research, analyze the variable sampling scheduling in network control system, establish the model of variable sampling network control system, this paper main research content as follows:First of all, study the True Time toolbox function modules what can comprehensively reflect the characters of control and network transmission. Then based on the TrueTime simulation platform, with the DC motor as the controller object, set up a network control system. Analyze the affect of the network induced delay and packet loss in the performance of network control system. At the same time analyze the two classic scheduling algorithms:RM and EDF. Besides analysis problems existing in the network such as packet loss and delay. This paper proposes a packet loss compensation strategy; based on the uncertain of the network induce delay, design the variable sampling scheduler, online real-time monitoring network resources, according to the demand foe network resources of each control loop, dynamically adjust the sampling period of each control loop to realize the dynamic allocation of resources; Finally using basic function and structure of variable sampling simulation toolbox TrueTime and combined with MATLAB/Simulation toolbox, establish variable sampling network control system simulation model. Based on the network bandwidth, network packet loss and scheduling algorithm, simulation analysis was carried out on the variable sampling network control system. The results show that the variable sampling period makes the network control system performance to obtain effective improvement.