Navigation System CAN Network Design And Implementation Based On Time-triggered

The traditional navigation system uses serial interface communication, as it has manyadvantages of simply structure and long transmission distance, but along with thedevelopment of navigation equipment, the quickness and diversity of data transmission allhave greatly improved, the serial communication will not be able to meet the needs of themodern navigation system. In recent years, CAN bus technology has very outstandingadvantages in the level design, anti-interference ability, error detection mechanism as well asthe reliability and real time aspects, that has begun to spread in modern shipbuilding system.But CAN bus itself also has a lot of inherent defects, such as CAN bus uses an independentpreemptive mode of arbitration mechanism model, when it is in large volume and density ofdata, and is close to CAN bus rated bandwidth, low priority of information will lead togenerating a lot of data delay, even appearing the phenomenon of data loss. As transmissiontime of partly node has strict requirements in correctness and accuracy in the navigationsystem network, usually CAN bus has been unable to meet the real time.Aiming at the defects of CAN bus, this paper use the CAN bus session layer added timetrigger mechanism of TTCAN protocol which can improve the real time of network, theagreement of the underlying technology is completely consistent with CAN bus. In TTCANnetwork, the communication of each node is based on a global time, synchronized in offlinedesign time scheduling list, according to the schedule arrangement, completed thecorresponding operation in their respective established time window, avoided data delay in alarge amount of information, which can ensure that the information can be successfullycompleted operation in the maximum transmission period and ensure the real-time system.First of all the related specifications of TTCAN bus underlying technology and keytechnology are introduced in detail. Through analyzing the TTCAN protocol within thetime-triggered mechanism, time synchronization mechanism and the construction of timeschedule,combined with the characteristics of the ship navigation system device information,this paper designs the one-dimensional packing algorithms, particle swarm optimization anddynamic priority boost algorithm,which combined with TTCAN agreement to improvereal-time performance of ship navigation system. Then through summarizing the reliability ofnavigation system TTCAN network and the characteristics of redundancy technology, thispaper chooses static hardware redundancy technology to realize the redundant backup ofentire network; designs the redundancy and fault switch for the master node of TTCAN time trigger mechanism; designs the system matrix when the network structure changes, completesthe improvement of navigation system reliability.Finally, this paper builds the test environment of the navigation system TTCAN network,test and analyse the navigation system TTCAN network in the test environment, the results ofanalysis showed that the design improves the real-time and reliability of the time-triggerednavigation system CAN network.