Research On System Analysis And Co-design Of Networked Fractional-order Control System

The Network Control System (NCS) is an integrated product of control theory, computer technology, and network communication technology. It represents the development trend for automation technology and is potential for being applied widely in the future. The NCS is a feedback system which transmits data among the spatially distributed sensor, the controller, and the actuator so as to control the intended objects. The introduction of network has become a direct factor which can impact the performance of systems. Moreover, the fractional-order system can be used for resolving the problem of time-delay due to its ability of fully reflect the system information. The aim of this paper is to implement a series of experiments, so as to realize the co-design of hierarchical scheduling and fractional-order control.Firstly, the background and the research status of NCS, scheduling, and co-design are introduced and summarized. A hierarchical scheduling strategy which is adaptable to multiple control loops is provided to optimize the current scheduling algorithm. Meanwhile, a multiple simulation platform is established by the packet of TrueTime to verify the validity and superiority of this strategy.Secondly, fractional-order systems are introduced into the NCS. The current research of NCS normally relies on establishing complex network models. This method focused too much on impacts of network and external perturbation; thereby limiting the application of the control algorithm. In this dissertation, considering the impact of time-delay on network, a fractional-order system with strong robustness is introduced to analyze the stability and parameter tuning of the NCS. The simulation results show that parameters of the fractional-order systems do have impacts on the performance of control systems. Based to the frequency domain and cost function of systems, the controller parameters can be chosen, aiming to optimize the control effects.Thirdly, considering the impact of time-delay on NCS and the limitation of network resources, a generalized objective function of NCS which is made up of control signals, output errors and rise time is provided. Meanwhile, the co-design of control and scheduling is also carried out so as to adjust the period of sub-loop sampling, bandwidth allocation, and controlling parameters. It is can be seen from the stimulation that the NCS has a better performance by integrating the designed controlling and scheduling.At last, the research is summarized and further discussions in relation to this area are pointed out.