Research On Communication And Service Quality Of Unmanned System Air-ground Cooperation Based On DDS

With the development of modern technology,in order to reduce costs and improve productivity,robots are gradually applied to all aspects of society.The air-ground coordination of unmanned systems has a wide range of applications in military and civilian fields,such as geological surveys,agricultural information collection,traffic and road condition information collection,search and rescue in dangerous environments,reconnaissance and strikes,etc.In the past,the communication methods of the unmanned air-ground coordination system include Zigbee protocol,digital radio and wireless broadband.However,in a dynamic environment,the communication conditions are poor,and the mission robot equipment is heterogeneous,and there may be situations where the system nodes cannot communicate.At the same time,traditional communication methods cannot achieve decentralization and distributed information distribution,which has great limitations for the collaborative work between robots.DDS is a data-centric distributed communication method that supports rich quality of service strategies and is an effective solution for air-ground collaborative communication.However,there are still problems in DDS communication that the quality of service policy cannot be automatically matched and the fault-tolerant mechanism is weak.In this paper,aiming at these two key problems affecting the communication quality,the following work is specifically carried out:(1)Although DDS tunable policies provide fine-grained control over system QoS,when developing and deploying in dynamic environments where no-man’s-land coordination is involved,the system must be able to adjust QoS according to environmental conditions,setting QoS for multiple complex responses.Since it is not feasible to manage QoS manually in a dynamic system,this paper proposes an automatic QoS matching algorithm based on a decision tree to maintain the specified QoS configuration as the system changes dynamically.By collecting the communication data in the real environment,building a decision tree according to the demand label,and obtaining an optimized QoS policy group.The experimental results show that the optimal strategy group obtained by the QoS matching algorithm based on decision tree can significantly improve the communication quality of the system.(2)There are still some limitations in the fault tolerance support of DDS at this stage.First,DDS complicates the development and deployment of mission-critical applications by duplicating end systems for fault tolerance.Second,due to the limited memory capability of DDS-enabled mobile terminal systems,it is not feasible for DDS to use persistent profiles to maintain volatile memory or exchange data on mass storage.In high throughput scenarios,persistent services can become a performance bottleneck.This paper provides a flexible and comprehensive fault-tolerant mechanism for DDS,finds problems in time through fault detection,takes preventive measures,and recovers from software and hardware faults after the fault occurs.Through experiments,the system supports real-time fault detection and recovery,provides the ability to flexibly implement fault-tolerant modes,and the increase in overhead is not obvious.(3)This paper realizes the communication of the unmanned air-ground cooperative system based on the DDS communication mechanism.In the communication process of heterogeneous nodes,it can not only provide real-time optimized QoS policy groups for the system according to different requirements,but also provide a comprehensive fault-tolerant mechanism for the system.At the same time,the communication system realizes information exchange of heterogeneous nodes and flexible control of service quality,and the fault-tolerant mechanism greatly enhances the reliability of the system.