Filtering And Control For The IEEE 802.15.4 Based Networked Control System

Conventional control systems rely on wired connections to components such as sensors,controllers and actuators.With the development of wireless communication technologies,components of the control system can be connected using different wireless networks,forming the so-called wireless networked control systems(WNCSs).WNCSs integrate three elements of control,computing and wireless communication and have the advantages of low cost,easy deployment,easy expansion,and remote networking and thus are applied in home,industry,aerospace,agriculture,etc.However,compared with the wired communication,the wireless communication has more obvious communication constraints of network-induced delay and packet loss and packet disorder,which not only affects the performance of the control system,but also may cause instability of the control system in severe case;In addition,the introduction of wireless communication brings about new issues like node energy-efficiency and multi-packet transmission;these problems have attracted the attention of many researchers.As a specific wireless networked control system,IEEE 802.15.4 based networked control system deserves particular attention.On the one hand,the IEEE 802.15.4 standard is widely used in wireless sensor and actuator networks;on the other hand,the standard is the basis for the ZigBee protocol which is widely used in Internet of Things,the ISA100.11 a and WirelessHART protocols which are widely used in industrial automation.The IEEE 802.15.4 standard is a wireless standard defined to support low-cost,low-data-rate communication between devices,these devices are usually powered by batteries with limited capacity,so the energy efficiency problem becomes a hot issue in IEEE 802.15.4 networked control system.In addition,IEEE 802.15.4 networks support contention channel-access and hybrid channel-access.The hybrid channel-access is a big advantage of IEEE 802.15.4 network,how to use this advantage to make reasonable resource scheduling is another issue worthy of attention.This thesis has studied these problems and obtained the following results:(1)Aiming at the tradeoff between filtering performance and energy efficiency in the IEEE 802.15.4 networked control system with contention channel-access,an adaptive CSMA/CA parameter tuning mechanism based on sensors' critical arrival rates is proposed for the first time.The difficulty in implementing this mechanism is to calculate the critical arrival rates of the sensors.To deal with this difficulty,this thesis presents two new linear matrix inequalities for solving the critical arrival rates of the sensors,which avoids the problem that the dimension of the traditional linear matrix inequality condition increases exponentially with the number of sensors causing the difficulty of calculating the critical arrival rates of each sensors.This critical arrival rates based adaptive CSMA/CA parameter tuning mechanism can increase the energy efficiency of the overall system while maintaining satisfactory performance of the filter.(2)Aiming at the tradeoff between system performance(including control trajectory and system lifetime)and contention-free communication resources in the IEEE 802.15.4 networked control systems with hybrid channel-access,a less conservative self-triggering model is designed and then a new control structure based on gain scheduler and network scheduler is proposed.Under the control structure,only the sensing data of the system is transmitted through the wireless network,one-step sensing data is used to calculate multi-step control inputs,and network scheduler implements resource scheduling based on a designed hybrid scheduling algorithm.The control structure optimizes the utilization efficiency of contention-free communication resources under the premise of ensuring satisfactory system performance.