Design Of The Low Latency Deterministic Networked Control System Based On IEEE 802.15.4 Standard

Wireless networked control system(WiNCS)has been a hot research aspect in industrial field due to the benefits of no cables,easy construction and maintenance.IEEE 802.15.4 standard is one of the most popular wireless person area network(WPAN)standards for its low latency and low energy consumption.In contention access period(CAP),IEEE 802.15.4 adopts CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance)protocol to transmit the data.However,this leads to that the larger the network size is,the worse success rate is.Contention free period(CFP)in IEEE 802.15.4 adopts guaranteed time slot(GTS)schedule,but with minimum fresh time not less than 15.36 ms,which could not satisfy real industrial demand.Different devices are not same sensitive to time delay,using GTS alone could not satisfy various industrial demands.Based on the above problems and the current research results of IEEE 802.15.4,WiNCS with multi-delay demands are studied in this thesis.This thesis first expounds the basic content of IEEE 802.15.4,and summarizes the research status of IEEE 802.15.4 in recent years and its applications.Then based on the TDMA(Time Division Multiple Access)instead of CSMA/CA,the algorithm of modeling the network with multi-delay is proposed.The basic idea of the algorithm is that the model classifies various delay demand devices into different groups to accommodate devices as many as possible.First of all,a device shakes hands with the coordinator for the first time to request access to the network.The coordinator classifies the device in a certain group by the demand delay of the device.Then devices in the same group will be assigned to different superframe time sequences to complete the expansion of network equipment.At last,some experiments have been done in this thesis such as data transmission and a real networked motor control system.The results of the experiments show the feasibility and efficiency of our algorithm.