1 Introduction

Beidou satellite navigation system (hereinafter referred to as Beidou System) is a global satellite navigation system independently built and operated by China focusing on the needs of national security and economic and social development. It is an important national space-time infrastructure that provides all-weather, all-time, high-precision positioning, navigation and timing services for global users. In accordance with the "three-step" development strategy, Beidou No. 1 system was completed in 2000 to provide services to China and its surrounding areas; In 2012, beidou-2 system was built to provide services to the Asia Pacific region; In 2020, beidou-3 system will be built to provide services to the world.

Beidou-3 system consists of space segment, ground control segment and user segment.Space segmentIncluding 24 medium circular orbits, 3 geosynchronous orbits and 3 inclined synchronous orbits, totaling 30 satellites;Ground control sectionIncluding 47 ground stations such as master control station, time synchronization / injection station and monitoring station, as well as ground facilities such as measurement and control and inter satellite link operation management;User segmentIncluding basic products such as chips, modules and antennas, as well as various terminal products and application systems. System has“Dynamic optimization, active evolution "," rich functions and diverse services "," technological innovation, independent control "," wide application and remarkable benefits "," open compatibility and global promotion "It has five characteristics [1-10], such as short message communication, satellite based enhancement, precision single point positioning, international search and rescue and other service functions. The global positioning accuracy is better than 10m, the speed measurement accuracy is better than 0.2m/s, the timing accuracy is better than 20 nanoseconds, and the service availability is better than 99%. The Asia Pacific region has better performance. It is a global public service product contributed by China to the world.

On July 31, 2020, the beidou-3 system was officially completed and opened, entering a new era of global service. The completion and opening of beidou-3 system is an important milestone for China to become a space power and a major contribution to the construction of global public service infrastructure [11]. The remarkable achievements are due to the establishment of a collaborative, high-quality and efficient Beidou system engineering management system and the exploration of an effective way of scientific management.

2 Beidou System Engineering Management

Beidou system undertakes the three major tasks of project construction, application service and international cooperation. It faces many difficulties and challenges in project management, such as wide range of fields, large system scale, large technical span, high index requirements, tight construction cycle, tight factor coupling, difficult quality control, high degree of risk, difficult stable operation and great impact of interruption, Based on the traditional aerospace system engineering management mode [12-18], it is necessary to use the new methods and concepts of system engineering to carry out management innovation in organization, technology, construction, quality and operation, and establish an engineering management system suitable for the characteristics of Beidou [19], as shown in Figure 1.

Figure 1 Beidou system engineering management system

2.1 organization and implementation system of "centralized, unified, efficient and coordinated"

2.1.1 organization of "centralized, unified and hierarchical responsibility"

Establish an organizational structure composed of China Satellite Navigation System Commission, leading organizational unit, system management office, implementation agency and task undertaking unit, and establish a chief designer system, expert consulting agency and technical support agency, as shown in Figure 2. Under the unified leadership of the satellite navigation system committee and the specific organization of the system management office, various institutions are responsible at different levels, establish a smooth, coordinated, efficient, standardized and orderly management and operation mechanism, effectively integrate multi-dimensional forces such as politics, industry, research and learning, realize the organic integration of management, engineering and technology, and ensure resources The optimized allocation of factors and the smooth progress of work.

Figure 2 Beidou system organization

2.1.2 coordination mechanism of "multi-level and high efficiency"

In order to ensure the efficient operation of the organization, multi-level and near real-time coordination mechanisms such as navigation committee meeting, general coordination meeting, chief engineer's office meeting and special coordination meeting are established. The meeting of the navigation committee is organized by the satellite navigation system committee to focus on coordination, research and decision-making on major issues, and consider key matters such as annual work and plans; The overall coordination meeting is organized by the leading organization unit to make decisions on major technical and management issues; The chief engineer's office meeting is organized by the system management office to coordinate and make decisions on important technical issues and give suggestions on management issues; The special coordination meeting is organized by the overall project to coordinate and make decisions on special issues in time. The establishment of this mechanism ensures that thousands of problems are solved timely and effectively, and provides strong support for the rapid promotion of the system.

2.1.3 overall design department of "small core and large periphery"

Mr. Qian Xuesen proposed that the overall design department plays an important role in system engineering and is an essential technical unit in the development of the whole system [12]. Satellite navigation system is a giant space system characterized by active evolution. It is more necessary to establish a strong overall design department. The project innovatively puts forward the construction mode of cross industry and cross field "small core and large periphery" overall design department, and establishes an overall design department with the system management office and its affiliated China Satellite Navigation Engineering Center as the small core and 5 expert groups, 9 sub centers and more than 10 advantageous scientific research institutes as the periphery, as shown in Figure 3. It has played an important role in the collaborative, high-quality and efficient construction of Beidou system.

Figure 3 Overall design department of Beidou project with "small core and large periphery"

2.2 "incremental development, independent and controllable" technological innovation system

2.2.1 evolution route of "incremental development and gradual improvement"

In the construction and development of beidou-3 system, the new mode of incremental development of aerospace system is explored and practiced, which provides a scientific methodology for the continuous iterative evolution of beidou-3 system and the pursuit of better performance.Strategic planningAccording to the three-step strategy, after Beidou No. 1, No. 2 and No. 3, the technical system has changed from regional active, regional passive to global passive, and the capability level has changed from solving the problem, catching up with foreign countries to surpassing.Overall scheme, the overall scheme of beidou-3 system has evolved several versions iteratively since 2011, gradually establishing the goal of surpassing foreign systems and achieving world-class.Project implementation, the 30 beidou-3 satellites are divided into three batches. According to the on orbit performance of the previous batches of satellites and the upgrading of the overall scheme, the technical status requirements are upgraded batch by batch to continuously improve the satellite performance.Technical system, the service types are expanded from two types of beidou-2 to seven types of beidou-3; From satellite ground networking to inter satellite ground integrated networking using inter satellite links; The system operation has developed from relying on ground control to constellation independent operation.

2.2.2 technical system of "top-level optimization and integration"

The technical system of satellite navigation system determines the function and performance. Beidou system optimized the technical system from the top level, broke through the core technologies such as multi service integration, inter satellite link, heterogeneous hybrid navigation constellation, on-board atomic clock and downlink navigation signal, and laid a foundation for the comprehensive improvement of service function and performance. A new satellite navigation system integrating multiple services such as navigation and positioning / global message communication / satellite based enhancement / international search and rescue / precision single point positioning has been created, which has greatly enriched the service functions; The inter satellite link of the whole constellation is established, the information transmission between satellites is realized, the satellite orbit measurement accuracy reaches the centimeter level, the global high-precision navigation independent of overseas ground stations is realized, and an important support is provided for autonomous navigation; The first global heterogeneous hybrid constellation of geosynchronous / inclined geosynchronous / mid circle multi orbit in the world is innovatively designed, which expands the service function of satellite navigation system; The main and backup satellite clock system combining spaceborne hydrogen clock and spaceborne rubidium clock with independent intellectual property rights is developed to ensure high-precision ranging and timing; The downlink navigation signal modulation mode with independent intellectual property rights is designed to improve the anti multipath and anti-interference ability of Beidou 3 signal [2,3,6,7,20].

2.2.3 research system of "innovation breakthrough, independent control"

In terms of independent innovation of key technologies,In view of the technical difficulties and core keys of the project construction, more than 160 key technologies have been systematically arranged. In order to ensure the success of the project, the overall project manager as Party A is responsible for the coordination and management of all projects, the domestic advantageous unit as Party B carries out specific research and research, and the project related large-scale system as Party C monitors the research results; The digital twin system of ground and on orbit test shall be established simultaneously, the key technology breakthrough achievements shall be fully verified, and continuous iterative improvement shall be made to ensure the rapid and comprehensive transformation of achievements.

In terms of self-control of localization device components,Advance the layout, formulate the independent development route of "engineering model leading, application verification promotion, phased realization and large-scale drive", establish a three-tier management system of "decision-making, consultation and implementation", and establish a special coordination organization to take charge of overall decision-making and coordinate the development, application and other work; The expert consultation organization is responsible for the formulation of standards and specifications, basic technical research and technical problem coordination; Each system of the project is responsible for the development, verification and application of components, and constantly put forward suggestions for product optimization and improvement during the development process, so as to effectively promote the maturity of product development. Since the independent and controllable implementation, 100% localization of key components has been realized.

2.2.4 state control mode of "six in one, whole process closed loop"

According to the characteristics of Beidou system, a six in one state control mode of "design, test, evaluation, integration, operation and coordination" is established, with "design" output state, "test" verification state, "evaluation" master state, "integration" confirmation state and "operation" optimization state. General problems are directly coordinated and solved for technical problems in the process, Complex problems are solved coordinately after analysis, research and verification. This mode realizes the closed-loop control and management of Beidou system technical state, as shown in Figure 4.

Figure 4 Six in one implementation mode

2.3 construction management system of "parallel promotion and competitive selection"

Optimize the overall design, key technology research, test verification, development networking, operation service and other work processes, and realize high parallelism and rapid iteration. At the same time, introduce the competitive selection mechanism to mobilize the national advantageous resources for intelligence research. Therefore, the construction management mode of "parallel promotion and competitive selection" was established, and the "China speed" of launching 18 arrows and 30 satellites in two and a half years and completing the Beidou 3 system six months in advance was created.

Create a new batch production mode for aerospace products.Based on the traditional scientific research and production management mode of single satellite and single arrow, a new batch production mode of aerospace products with "centralized design, unified state, full production, batch acceptance, flow operation and rolling backup" is established, which realizes the high-density delivery of satellite and arrow according to the plan.

The development process is comprehensively optimized.Establish the remote test mode of satellite launch site, optimize the test process of launch vehicle launch site, and carry out the test and evaluation of multiple services in parallel, so as to shorten the satellite ground docking time by 50% and the test and evaluation time from 90 days to 28 days.

The test verification guarantee is promoted in a systematic manner.The digital twin test and evaluation system of "integration of satellite and ground, combination of virtual and real, accuracy and credibility" has been constructed, the on orbit test, satellite ground docking, on orbit test and performance evaluation have been carried out in an overall manner, the iterative evolution mode of "development evaluation improvement revalidation" has been established, the system state and performance have been continuously optimized and improved, and the "completion is service and service is effective" has been realized.

Introduce the mechanism of competitive selection and gather intelligence to tackle key problems.In terms of the construction of R & D team, establish a multi-level and multi-point benign competition pattern from overall to subsystem, and then to single machine. According to the principle of "homogeneous and heterogeneous guarantee development, real-time supplement and guarantee progress", two satellite collectives, two load collectives, two types of satellite platforms and several key single machines are arranged for multi-point. In terms of promotion strategy, 30 satellites implement the tasks in batches and proportions by means of comprehensive evaluation and bidding, so as to not only fully maintain the competitive pressure, but also mobilize the enthusiasm of all parties to the greatest extent.

2.4 quality control system of "system guarantee and risk forward"

2.4.1 quality reliability assurance of "four systems"

Traditional aerospace quality management is mainly oriented to spacecraft, focusing on the whole process quality control and refined quality management. Beidou system quality management adheres to the concept of "comprehensive coverage, prevention first, source control and unremitting efforts", runs through large systems - engineering systems - subsystems and single machines, and adds third-party evaluation, supervision and basic guarantee, Establish the quality management mode of "reliability design, test and verification, evaluation and supervision and basic guarantee", as shown in Figure 5.

Figure 5 Quality management mode of "four systems"

reliability designMainly for different levels of large-scale system, system and single machine, carry out the design and decomposition of reliability indicators, and establish quality characteristic index systems such as availability, continuity and integrity.Test verificationCarry out various simulations, tests and tests from bottom to top to verify whether different levels of large system, system and single machine meet the index requirements. At the large-scale system level, establish a ground test verification system to test and evaluate the overall scheme and the realization of key indicators; At the system and single machine level, carry out single machine level, subsystem level and system level test verification to ensure comprehensive test coverage and complete and effective system.Evaluation and supervisionQuality supervision and evaluation are mainly carried out by relying on the whole system and whole process development activities such as reliability design, test and verification of the project by the third party. At the large-scale system level, establish a global continuous monitoring and evaluation system to monitor and evaluate the service performance of Beidou system; At the system and stand-alone level, establish a product supervision and acceptance system and implement the maturity evaluation of key stand-alone and departmental components.Basic guaranteeImplement special reliability improvement to realize the reliability growth of single machine, subsystem, system and large system; Establish Beidou Standardization Technical Committee, build Beidou standard system and promote the healthy development of navigation industry.

The establishment of the "four systems" quality model has achieved the quality objectives of "zero defects" in Beidou product development, "zero faults" in networking and launch, and "zero interruption" in operation and service, and ensured 100% success in the 18 arrow 30 satellite launch networking of Beidou 3 project.

2.4.2 risk analysis and prevention and control mechanism of "control guarantee chain"

In view of various risks in progress, development, launch and stable operation, the risk control guarantee chain of "multi-source data fusion, risk cognitive analysis, qualitative and quantitative combination, risk dynamic assessment, hierarchical transmission and risk early warning control in advance" is innovatively established, forming a closed-loop control of risk "identification assessment prevention and control", It has realized the successful transformation from traditional "quality forward" to "risk forward".

Risk perception analysis of multi-source data fusion, multi-source data at different levels (large-scale system, system, single machine product), different time domains (initial sample, normal sample, test stage) and different airspace (ground, on orbit) are used to carry out multi-dimensional, all-round and whole process risk identification and analysis by comprehensively adopting quality intersection analysis method, risk matrix evaluation method, etc.Combining qualitative and quantitative risk dynamic assessment,The combination of qualitative analysis and quantitative calculation is used to comprehensively evaluate the identified risks, judge the occurrence probability, impact object and hazard degree of the risks, classify and grade them, and continuously carry out risk assessment and dynamically adjust the risk level according to the changes of risk factors and the implementation of control and guarantee measures.Hierarchical transmission and risk early warning control in advance,Transfer all risks from top to bottom, formulate prevention and control and guarantee measures by classification and classification, timely release risk early warning information, pay close attention to the implementation of control and guarantee measures, and conduct special review on risk prevention and control in key links such as product acceptance, system transition and Factory review.

2.5 "problem oriented, four in one" fine and stable operation system

In order to ensure the continuous and stable service of the system, a whole process and multi-means fine and stable operation system integrating "operation and maintenance, monitoring and evaluation, fine and stable improvement and smooth transition" is constructed, as shown in Figure 6. The system is problem oriented, finds and anticipates problems through "monitoring and evaluation", studies and solves problems through "fine stability improvement", implements problem-solving measures through "operation and maintenance", realizes system service stability and performance improvement through "smooth transition", and realizes long-term fine stability closed-loop control.

Figure 6 Beidou system fine and stable operation system

Operation and maintenanceCreate a "multi-party joint guarantee" mechanism for operation control, measurement and control, inter satellite and satellite systems, build a three ring data integration system of "inner ring (system operation service data), middle ring (product development status data) and outer ring (external monitoring and evaluation data)", implement intelligent operation and maintenance based on big data, cloud computing and artificial intelligence technology, and realize real-time online evaluation of the system Rapid fault diagnosis and positioning, fault prediction and early warning, auxiliary decision support, and improve the scientific and intelligent operation management level.Monitoring and evaluationBuild a global distributed monitoring and evaluation network, carry out normalized monitoring and evaluation on the system service performance and operation status, and timely find the existing problems and weak links of the system.Fine stability improvementAccording to the problems found in monitoring and evaluation, analyze the deep causes, research and propose solutions, and carry out key technical research and engineering improvement.smooth transitionFrom the aspects of space segment, ground segment, user segment and signal segment, we will orderly implement the smooth transition from Beidou 2 to Beidou 3 system, so as to ensure that hundreds of millions of users will not be affected during the system transition.

Since the beidou-2 system provided services at the end of 2012, the system has operated continuously and stably for 8 years without interruption, and the positioning accuracy has been improved from 10m to better than 5m, providing high-quality services for the world.

 

3 conclusion

Beidou system is a successful practice of complex aerospace system engineering, which enriches the connotation of aerospace management system. On the basis of inheriting China's traditional aerospace engineering management mode, we have realized innovation and development according to the characteristics of Beidou system, and formed a Beidou system engineering management mode with Chinese characteristics. Scientific management and management science have achieved high quality, high speed and high efficiency in the construction of Beidou system. The innovative management mode explored and established in the construction of Beidou system has been fully verified in Beidou project, which can provide reference for engineering management in aerospace and other fields. In the follow-up, a more ubiquitous, integrated and intelligent national integrated positioning, navigation and timing (pnt) system based on Beidou system will be built. The Beidou project management mode will also be continuously innovated and developed to promote the development of Beidou to a higher level and higher quality.

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