Research And Implementation Of Time Synchronization In Airborne Test System Based On EtherCAT

Airborne test system is used for collecting various analog and digital flight data of an aircraft and its subsystem,and also responsible for storage,analysis,processing and telemetry of these flight data.With the incense demanding of flight tests,there are more and more parameters need to be test and the test data rate is getting higher and higher,the conventional PCM-based airborne test system has become increasingly unable to meet the aircraft test requirements for its high cost and limited network flexibility,data bandwidth and transmission distance.EtherCAT is a real-time Ethernet technology which through using bus topology at the physical layer as well as a forward immediately after receiving communication method rather than the traditional storage and forward way,has overcome the real-time and delay jitter shortage of Ethernet using in real-time control system,and is able to meet the airborne test system for real-time,high-speed,synchronous,and reliability requirements,with good prospects for development.Based on the project-"Research on key Technology of Data Acquisition System Based on Real-time Ethernet and its Implementation and Verification",a deep research on the design and implementation of time synchronization and clock module is provided in this thesis.Time synchronization accuracy is an important indicator of Airborne test system performance.To achieve precise time synchronization,we must have an external time synchronization benchmark,and a way to ensure that other collectors are synchronized to the benchmark.The design of the system clock module is introduced in this thesis firstly,which provides the system time reference collecting from the GPS,IRIG-B and IEEE1588,to ensure the quality and continuity of the clock source.Then,the time synchronization technology of airborne test system based on the EtherCAT is introduced,which can achieve precise time synchronization between collector and master by using independently researched and developed master software.Finally,a system test platform is built,on which the time synchronization system is tested.The test results show that the acquisition stations in the system can reach synchronization accuracy within 1 microsecond and the design goals are achieved.