The Research Of Time Measurement And Clock Synchronization Methods Based On Flexray

With the rapid development of automotive electronic technology, FlexRay which is anew generation of automotive network is more and more widely used in modernautomotive control system. High-speed, reliable and real-time features can satisfy thestrong demand of the modern vehicle,such as automotive suspension, ABS and so on. Thisthesis is aimed at enhancing time measurement procedure and the precision of clocksynchronization, and researchs the method of time measurement and clock synchronizationprocess in FlexRay networks. It has actual value and significance for the widespread useof the FlexRay bus.First, to solve the problem that the decoding correction and delay compensation lead to,this thesis analyzes FlexRay time measurement process, and leads out a method of timemeasurement based on analytic model. Compared with the method of time measurement onFlexRay protocol, the method of time measurement based on analytic model does not solvethe problem. To solve this problem, it improves the method of time measurement inFlexRay protocol combined with the clock synchronization algorithm in IEEE1588protocol.And then,this thesis researches the clock synchronization algorithm on FlexRayprotocol. After analyzing the fault-tolerant midpoint(FTM) algorithm, there is a transmissiondelay which can lead to the clock synchronization drift. In order to solve the defect offault-tolerant midpoint in FlexRay protocol, the single-node fault-tolerant synchronizationalgorithm of FlexRay based on the improved time measurement is proposed. It canachieve clock synchronization with only one synchronization node and optimize theprecision of clock synchronization.Finally establish the simulating system combining the FlexRay real nodes to testify theslots distributing methods on the CANoe platform. Through the test, the results proved thatthe method is feasible.