Co-Design Of Control And Scheduling For Networked Control Systems With Communication Constraints

Networked control systems(NCS)is the product of the combination of network communication technology and traditional control system.It can solve the problems of complex wiring and short transmission distance of traditional control system.It has been applied to various fields such as industrial automation,robot,automobile,space exploration and so on.However,the introduction of network will also bring some adverse effects to the control system,such as network induced delay,packet loss and so on.While maximizing the advantages of networked control system,how to minimize the impact of adverse factors on networked control system is the focus of research.There are two main methods to improve the performance of networked control system, which are the control method for the controlled object itself and the scheduling method for the network.The two methods can be combined in the design of network and the quality control of service.Based on this,this paper has carried out the following research on the collaborative design of control and scheduling:Firstly,a priority and sampling period scheduling method based on fuzzy logic is proposed.This method uses priority and sampling period scheduling at the same time,which can reasonably allocate network bandwidth resources.In addition,for the networked control system that meets the H_∞performance index,a sufficient condition is given to make the system asymptotically stable and meet the existence of the maximum sampling period of the H_∞performance index.Finally,the simulation results show that this method not only ensures the network control system to achieve the established performance index,but also saves the limited network bandwidth resources.Secondly,a collaborative design method of robust control and sampling period scheduling is proposed.The sampling period is switched between several fixed values according to the size of the system error.The state feedback matrix K satisfying the H_∞performance index is calculated according to the sampling period,and the corresponding K is selected according to the current sampling period to calculate the control quantity.It can avoid the strong conservatism caused by considering both time-varying sampling period and time-varying delay.When designing the robust controller,Markov chain is used to describe the random packet loss of the system,and the nominal point method is used to determine the norm bound of the system uncertainty term composed of time delay.Finally,the numerical simulation results verify the feasibility and effectiveness of the collaborative design method.Thirdly,a collaborative design method for control and scheduling of generalized networked control systems based on bald eagle search(BES)optimized least squares support vector machine(LSSVM)is proposed.In this method,vulture optimized least squares support vector machine is used to predict the network induced delay,and the predicted delay is applied to the sampling period scheduling.The variation range of the sampling period is divided into several sections,the maximum value of each section of the sampling period is taken,and the state feedback matrix meeting the exponential stability H_∞performance index under each maximum sampling period is calculated respectively.The controller selects the corresponding feedback matrix according to the current sampling period to calculate the control quantity.Finally,the simulation results show that the collaborative design method has good results.