Dynamic Observer And Pole-Zero Assignment For Fault Detection Of Networked Control Systems

With the development of network technology and the country’s vigorous promotion of intelligent manufacturing,the networked control system has gradually applied industrial processes such as smart factory and mobile robot collaborative control.The networked control system has the advantages of good scalability,easy connection configuration,and strong mobility,which is not available in traditional control systems.However,sharing the transmission medium in the communication network makes the inevitable occurrence of network transmission delay,data packet loss,and other factors will reduce the reliability and real-time performance of the control system.This is the main challenge for networked control systems when applied to need high reliability and real-time industrial control processes.With the rapid development of Fault detection technology in recent years,provides a solution for improving the reliability of the networked control system to monitor the operating status of the various components of the networked control system and detect faults in time.Aiming at the problem that traditional observers zero cannot be assigned freely,this paper proposes a pole-zero assignment method of the dynamic observer for fault detection.Zero of dynamic observer assigned to the spectrum of the energy concentration of the disturbance to block the impact of the disturbance on the residual with the characteristics of the dynamic observer’s zero can be assigned freely.H2/H∞ method is used to optimize the pole of the dynamic observer,so that the residual is robust to disturbances and sensitive to faults.This paper comprehensively considers the effects of zero and poles on the performance of observers in fault detection,so that the residual has a better suppression effect on disturbances and has a stronger sensitivity to a fault.The main work and achievements in the article are summarized as follows:(1)A model of networked control systems is constructed.The influence of network transmission delay on the system is linearized and modeled as an external disturbance.The unknown input observer is thoroughly understood and studied,and the design steps and key points of the unknown input observer are given.The fault detection of network systems with unknown input observer is realized.By constructing a set of more suitable feedback matrices,the transfer function matrix of network transmission delay to residual is zero matrices,which eliminates the influence of network transmission delay on residual.(2)The dynamic observer is analyzed.The feedback part of the dynamic observer is neither the proportional feedback of the residual in the traditional proportional observer nor the simple proportional-integral feedback of the signal in the proportional-integral observer,but a dynamic system of the residual as input.The feedback part of the dynamic observer is similar to the description of a linear time-invariant dynamic system,so it is called the dynamic observer.At the same time,the dynamic observer has a zero point that can be freely assigned.(3)A pole-zero assignment method for fault detection of the dynamic observer is proposed.The performance of the observer in fault detection is affected by both zero and pole,but currently,researchers usually only consider the effect of the pole on the performance of the observer and ignore the role of zero.This paper comprehensively considers the impact of zeros and poles on the performance of observers in fault detection proposes a pole-zero assignment method for fault detection of the dynamic observer.Analyze the frequency distribution of external disturbance such as network transmission delays and sensor measurement disturbances,and configure the observer’s zero to the frequency spectrum of the disturbance signal to block the influence of disturbance on the residual,and then optimize the pole of the dynamic observer.(4)Fault condition analysis experiment of the positioning system is carried out,the fault detection scheme of the positioning system is designed,and carried out the simulation experimental verified the fault detection performance of dynamic observer.The influence of the positioning system’s fault on the yaw angle of the two-wheel vehicle is analyzed,and the scheme of fault detection for the positioning system through the yaw angle of the two-wheel vehicle is designed.Dynamic observer and other observers fault detection simulation results show that the proposed pole-zero assignment method for dynamic observer fault detection in this paper is superior to the unknown input observer,proportional observer,and proportional-integral in both the disturbance suppression ability and the fault sensitivity.Compared with other observers,the dynamic observer’s fault detection performance is significantly improved.Finally,the data flow of the whole system is completed by combining LEGO EV3 and wireless indoor positioning systems and provided the basic conditions for subsequent research.