| As the pace of human beings into space is faster and faster,large space stations,space power plants,space factories and other space infrastructure will soon appear.In these large spatial distributed mobile platforms,deterministic data transmission networks,such as Time Sensitive Network(TSN),are used within space facilities,and wireless links are used between these facilities.If the transmission characteristics of time-sensitive networks are extended to wireless links,deterministic communication and distributed collaboration between spatial nodes can be supported.This time-sensitive network of wired and wireless convergence is also a development direction that is being actively researched in industry and academia.At present,the mainstream technologies to realize TSN integration include TSN and Wi Fi integration and TSN and 5G integration,the whole network time synchronization is the basis of integration and fusion.In order to meet the future deterministic networking requirements of spatial distributed mobile platform,this paper proposes a clock synchronization system implementation scheme based on TSN and Wi Fi integration,and studies the synchronization reliability mechanism for platform dynamics.The specific research contents of this paper are as follows:This paper presents a scheme design of synchronous system for spatial distributed mobile platform.Firstly,the typical application scenarios of synchronization system in spatial distributed mobile platform are investigated,the key technologies of time synchronization are analyzed,and the module architecture of core synchronization device is designed.The key time synchronization mechanism in synchronous devices and the Clock Domain Crossing(CDC)circuit used to avoid metastable problems are discussed in detail.Finally,aiming at the impact of timestamp on synchronization accuracy,based on the prototype verification system of the moving platform developed by the laboratory,the hardware timestamp synchronization scheme in the wireless bridge is designed and tested.This paper studies the reliability of synchronous system of spatial distributed mobile platform.On the one hand,for wired domains,multiple redundancy mechanisms such as synchronous path redundancy and GM redundancy are used to avoid the loss of synchronization messages when network faults occur.On the other hand,for the wireless domain,firstly,the soft handover algorithm is combined to realize the continuity of the synchronization protocol in the handover process of the mobile node.The original IEEE802.1AS process is improved,the Best Master Clock Algorithm(BMCA)is achieved by exchanging local clock vector information between wireless Access points(AP)in advance,this ensures seamless time synchronization and smooth service transition.Secondly,for mobile nodes with fixed motion range or predictable motion path,a model response strategy can be established in the network according to their motion rules,and periodic task scheduling can avoid frequent exchange of node state and clock information between Aps.Finally,for the problem of clock jitter caused by randomness of wireless channel,the mechanism of node clock tracking and path delay filtering is studied to further enhance the synchronization reliability of wireless nodes.The synchronization scheme design and reliability enhancement mechanism proposed in this paper,closely combined with the latest technical standards of TSN and Wi Fi,can not only be applied to the spatial distributed mobile platform network,but also have important reference value for the current widely concerned industrial Internet field. |
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