發(fā)布時(shí)間：2018-06-09 01:46

  本文選題：實(shí)時(shí)系統(tǒng) + 通信機(jī)制　； 參考：《國防科學(xué)技術(shù)大學(xué)》2013年博士論文

【摘要】：近年來,嵌入式實(shí)時(shí)系統(tǒng)的應(yīng)用已經(jīng)廣泛滲透到家電、工業(yè)控制、汽車、火車、航空航天等各個(gè)行業(yè)。一方面,許多原來由機(jī)械和液壓完成的功能逐步被電子系統(tǒng)取代,各種控制系統(tǒng)電氣化程度不斷提高,另一方面,人們對系統(tǒng)的安全性、舒適性等功能和性能的要求越來越高。這些變化要求實(shí)時(shí)系統(tǒng)提供更加強(qiáng)大的計(jì)算能力,因此,實(shí)時(shí)系統(tǒng)的處理器向多核方向發(fā)展,且處理器的數(shù)量急劇增長。這就對實(shí)時(shí)系統(tǒng)的通信機(jī)制提出了越來越嚴(yán)苛的要求。本文對實(shí)時(shí)系統(tǒng)通信機(jī)制進(jìn)行了探索和研究,并對多核任務(wù)間通信機(jī)制和實(shí)時(shí)通信網(wǎng)絡(luò)進(jìn)行了設(shè)計(jì)和優(yōu)化,主要研究內(nèi)容包括以下四個(gè)方面:(1)多核嵌入式實(shí)時(shí)系統(tǒng)任務(wù)間通信機(jī)制研究在實(shí)時(shí)系統(tǒng)中,任務(wù)在訪問共享變量時(shí),需要采用通信機(jī)制來保證訪問的互斥性。多核體系結(jié)構(gòu)本身具有高性能、低功耗等多種優(yōu)勢,其在實(shí)時(shí)系統(tǒng)領(lǐng)域的應(yīng)用越來越廣泛。由于多核結(jié)構(gòu)的分布式特性,通信機(jī)制的設(shè)計(jì)變得更加復(fù)雜。目前,針對多核結(jié)構(gòu)的通信機(jī)制主要包括鎖機(jī)制和無等待機(jī)制兩大類,然而,這兩類機(jī)制在存儲開銷和系統(tǒng)可調(diào)度性方面各有優(yōu)劣,無法兼顧兩個(gè)指標(biāo)。本文提出了一種新穎的彈性多處理器通信機(jī)制(FMCS),該機(jī)制通過一種我們提出的啟發(fā)式優(yōu)化算法為每個(gè)共享變量分配其最適用的通信策略和沖突處理策略,具有存儲開銷低和系統(tǒng)可調(diào)度性好的優(yōu)勢。FMCS機(jī)制給出了每個(gè)任務(wù)在最壞情況下的響應(yīng)時(shí)間計(jì)算公式,從而能夠?qū)��?shí)時(shí)系統(tǒng)進(jìn)行確定性的時(shí)間分析。通過實(shí)驗(yàn)驗(yàn)證,結(jié)果表明:FMCS能夠在保證系統(tǒng)可調(diào)度性的前提下大幅度降低存儲開銷,且當(dāng)系統(tǒng)利用率達(dá)到90%以上時(shí),使用FMCS機(jī)制仍能保證系統(tǒng)可調(diào)度,因而FMCS具有較高的可擴(kuò)展性。(2)實(shí)時(shí)通信網(wǎng)絡(luò)的消息部署研究實(shí)時(shí)系統(tǒng)用于實(shí)現(xiàn)控制任務(wù)時(shí),控制路徑的延遲大小對控制精度影響重大,因此,要達(dá)到較高的控制精度就必須將實(shí)時(shí)系統(tǒng)控制路徑的延遲控制在一定范圍內(nèi)。在基于模型的開發(fā)中,系統(tǒng)的延遲屬性可通過對功能模型進(jìn)行仿真和模型檢驗(yàn)來提前驗(yàn)證。為了確保最終部署的系統(tǒng)仍保持系統(tǒng)需要的屬性,在任務(wù)和通信消息實(shí)現(xiàn)時(shí)需要保證模型的延遲屬性不變。但是,在某些情況下,完全保證模型的延遲屬性不變是不可能做到的,此時(shí),需要在模型中增加通信延遲,并重新修改模型,進(jìn)行迭代設(shè)計(jì)。消息部署的延遲在模型延遲屬性中占據(jù)相當(dāng)大的比重,然而,目前對于基于模型開發(fā)過程中的消息部署問題的研究還十分缺乏。本文建立了一種新穎的低延遲消息部署模型(LLMD),該模型是一種基于時(shí)間觸發(fā)通信機(jī)制Flex Ray調(diào)度問題的數(shù)學(xué)模型,能夠在保證普通路徑的延遲時(shí)限和系統(tǒng)的可調(diào)度性的前提下,在關(guān)鍵控制路徑中引入盡可能少的單位延遲。最后,本文利用一個(gè)X-by-wire實(shí)例和一個(gè)主動(dòng)安全實(shí)例對該模型進(jìn)行了實(shí)驗(yàn)驗(yàn)證,結(jié)果表明:該模型能夠在有限時(shí)間內(nèi)找到消息部署優(yōu)化方案,且該方案在滿足系統(tǒng)可調(diào)度性的前提下會(huì)盡可能少的引入額外延遲。(3)實(shí)時(shí)通信網(wǎng)絡(luò)安全機(jī)制研究隨著航空電子、汽車電子等系統(tǒng)中聯(lián)網(wǎng)設(shè)備的增加和電氣化程度的提高,系統(tǒng)的可訪問性急劇上升,這導(dǎo)致實(shí)時(shí)通信網(wǎng)絡(luò)面臨一系列嚴(yán)重的安全隱患。本文提出了SSS機(jī)制——一種用于實(shí)時(shí)通信網(wǎng)絡(luò)的智能安全機(jī)制,該安全機(jī)制能夠有效抵御偽造和篡改攻擊,大大提高了通信系統(tǒng)的安全性,并允許在負(fù)載較輕的處理器上以軟件方式代替原本由硬件實(shí)現(xiàn)的安全相關(guān)操作(簽名、認(rèn)證、密鑰生成等),能夠顯著降低硬件開銷。本文提出了SSS機(jī)制的優(yōu)化設(shè)計(jì)模型,該模型在保證通信安全性和系統(tǒng)可調(diào)度性的前提下,合理安排消息、密鑰和任務(wù)的調(diào)度,盡可能少的引入硬件單元,顯著降低了實(shí)現(xiàn)成本;該模型提供多種安全級別,支持設(shè)計(jì)人員根據(jù)通信系統(tǒng)負(fù)載選擇最佳安全級別。最后,我們使用兩個(gè)工業(yè)實(shí)例對提出的SSS機(jī)制進(jìn)行了實(shí)驗(yàn)驗(yàn)證,結(jié)果發(fā)現(xiàn):SSS機(jī)制能夠在有限的時(shí)間內(nèi)找到優(yōu)化方案,且與現(xiàn)有的Flex Ray安全機(jī)制相比,能夠大大降低硬件開銷。(4)實(shí)時(shí)通信網(wǎng)絡(luò)的可擴(kuò)展性研究隨著嵌入式系統(tǒng)功能的不斷增加和性能的迅速提高,實(shí)時(shí)系統(tǒng)中的任務(wù)越來越多,任務(wù)間的通信數(shù)據(jù)急劇增加,從而對通信網(wǎng)絡(luò)的可擴(kuò)展性提出了更高的要求。本文提出了一種高可擴(kuò)展實(shí)時(shí)通信網(wǎng)絡(luò)結(jié)構(gòu)HSRN。HSRN通過在Flex Ray通信系統(tǒng)中引入交換機(jī)將通信系統(tǒng)分割成多個(gè)分支(branch),有效隔離了廣播域,從而大大提高了通信系統(tǒng)的可擴(kuò)展性。HSRN中的交換機(jī)采用了一種我們設(shè)計(jì)的消息可緩存交換結(jié)構(gòu),該交換結(jié)構(gòu)允許跨分支通信消息在發(fā)送端和接收端的不同位置時(shí)間槽上傳輸,且即使出現(xiàn)兩個(gè)分支的消息同時(shí)發(fā)向一個(gè)目標(biāo)分支的沖突情況,也可通過輸入端的緩沖隊(duì)列來解決沖突,從而放松了調(diào)度約束,允許通信網(wǎng)絡(luò)容納更多的消息,提高了網(wǎng)絡(luò)利用率。為了提高HSRN中各分支負(fù)載的均衡性,本文提出了一種負(fù)載均衡優(yōu)化算法,該算法能夠在有限時(shí)間內(nèi)找到最為合理的網(wǎng)絡(luò)分割方案,使得最大負(fù)載分支使用盡可能少的時(shí)間槽,從而保證了HSRN各分支的負(fù)載均衡,提高了實(shí)時(shí)通信網(wǎng)絡(luò)的可擴(kuò)展性。本文通過X-by-wire案例和一個(gè)合成案例對HSRN進(jìn)行了實(shí)驗(yàn)驗(yàn)證,結(jié)果表明:HSRN能夠在時(shí)間槽使用總數(shù)、負(fù)載均衡和交換結(jié)構(gòu)最小緩存配置之間進(jìn)行很好的優(yōu)化,在滿足網(wǎng)絡(luò)容量的同時(shí)兼顧了負(fù)載均衡,從而具有非常高的可擴(kuò)展性。綜上,本文對實(shí)時(shí)系統(tǒng)通信機(jī)制的若干問題進(jìn)行了研究,從不同角度對通信機(jī)制進(jìn)行了設(shè)計(jì)和優(yōu)化,提出了一系列的模型和優(yōu)化設(shè)計(jì)方法,對推動(dòng)實(shí)時(shí)系統(tǒng)通信機(jī)制的發(fā)展做出了積極的貢獻(xiàn),具有一定的理論意義和應(yīng)用價(jià)值。
[Abstract]:In recent years, the application of embedded real-time system has been widely permeated into various industries, such as household appliances, industrial control, automobile, train, aerospace and other industries. On the one hand, many functions completed by machinery and hydraulics are gradually replaced by electronic systems, and the degree of electrification of various control systems is constantly improved. On the other hand, people are safe and comfortable for the system. The requirements of sexual function and performance are becoming higher and higher. These changes require the real-time system to provide more powerful computing power. Therefore, the processor of the real-time system develops to the multi core direction, and the number of processors is increasing rapidly. This makes the communication mechanism of real-time systems more and more stringent. This paper is a communication mechanism for real-time systems. The research and research are carried out, and the communication mechanism and real-time communication network between multi core tasks are designed and optimized. The main research contents include the following four aspects: (1) the inter task communication mechanism of multi core embedded real-time systems is studied in the real-time system. The communication mechanism is needed to ensure the mutual access when the task is access to the shared variables. The multi-core architecture itself has many advantages, such as high performance, low power consumption and so on. It has become more and more widely used in the field of real-time system. Because of the distributed characteristics of multi-core structure, the design of communication mechanism becomes more complex. At present, the communication mechanism for multi-core structure includes two main categories, lock mechanism and no wait mechanism, however, this The two types of mechanisms have advantages and disadvantages in storage overhead and system schedulability. This paper proposes a novel flexible multi processor communication mechanism (FMCS). This mechanism uses a heuristic optimization algorithm proposed by us to allocate the most applicable communication strategy and conflict processing strategy for each shared variable. The.FMCS mechanism with low storage cost and good system schedulability gives the response time calculation formula for each task in the worst case, and can make deterministic time analysis of the real-time system. The results show that FMCS can greatly reduce the storage cost under the premise of guaranteeing the system adjustable, and when the system is adjustable, the storage cost can be greatly reduced. When the system utilization ratio is above 90%, the system can still ensure the schedulability of the system using the FMCS mechanism, so FMCS has high scalability. (2) a real-time communication network message deployment research real-time system is used to realize the control task, the delay size of the control path plays a significant role in the control precision. Therefore, the higher control precision must be achieved. The delay property of the system is controlled in a certain range. In the model based development, the delay properties of the system can be verified ahead of time by simulation and model test of the function model. In order to ensure that the final deployed system still maintains the required properties of the system, the model is guaranteed to be extended when the task and communication message are implemented. However, in some cases, it is impossible to completely guarantee the delay attribute of the model. At this time, it is necessary to add communication delay in the model and revise the model for iterative design. The delay of message deployment is a large proportion of the model delay attributes. However, the current model is developed for the model based on the model. A new low delay message deployment model (LLMD) is established in this paper. This model is a mathematical model based on the scheduling problem of Flex Ray based on time triggered communication mechanism. It can control the key control path on the premise of guaranteeing the delay time limit and the schedulability of the common path. In the path, the minimum unit delay is introduced. Finally, a X-by-wire example and an active security example are used to verify the model. The results show that the model can find the optimal scheme of message deployment in a limited time, and the scheme will be introduced as little as possible to meet the schedulability of the system. (3) (3) the research on the security mechanism of real time communication network, with the increase of networking equipment and the increase of electrification in the avionics, automotive electronics and other systems, the accessibility of the system has risen sharply, which leads to a series of serious security risks in the real time communication network. This paper proposes a SSS mechanism, a kind of real-time communication network. The mechanism of intelligent security, which can effectively resist forgery and tampering attacks, greatly improves the security of the communication system, and allows software to replace the security related operations (signature, authentication, key generation, etc.) which are originally implemented by hardware in a lighter load processor, and can significantly reduce the hardware overhead. This paper proposes a SSS On the premise of guaranteeing communication security and system schedulability, the model can reasonably arrange the message, key and task scheduling under the premise of ensuring communication security and system schedulability, and reduce the cost of implementation as little as possible. This model provides a variety of security levels and supports designers to select the best security level according to the communication system load. Finally, we use two industrial examples to verify the proposed SSS mechanism. The results show that the SSS mechanism can find the optimization scheme in a limited time, and can greatly reduce the hardware overhead compared with the existing Flex Ray security mechanism. (4) the scalability of the real-time communication network is based on the function of the embedded system. Increasing and rapidly increasing performance, more and more tasks in real time systems, the rapid increase of communication data between tasks, and higher requirements for the scalability of communication networks. A high scalable real-time communication network structure, HSRN.HSRN, is introduced in this paper by introducing a switch in the Flex Ray communication system. The system is divided into multiple branches (Branch), effectively isolating the broadcast domain, thus greatly improving the scalability of the communication system's extensibility.HSRN using a message caching switch we design, which allows transmissions of cross branch communication messages to be transmitted at different locations in the sender and receiving end, even if it appears. The messages of the two branches are simultaneously sent to the conflict of a target branch and can be solved by the buffer queue of the input terminal. Thus, the scheduling constraints are relaxed, the communication network is allowed to accommodate more messages and the network utilization is improved. In order to improve the equilibrium of the branch loads in HSRN, a load balancing optimization is proposed in this paper. The algorithm can find the most reasonable network segmentation scheme in the limited time, which makes the maximum load branch use as little time slot as possible, thus ensuring the load balance of each branch of HSRN and improving the scalability of the real-time communication network. In this paper, a X-by-wire case and a synthetic case are used to verify the HSRN. The results show that HSRN can be well optimized between the total amount of time slot, load balance and the minimum buffer configuration of the switching structure. It can satisfy the network capacity while balancing the load, thus having very high scalability. In this paper, several problems of the real-time system communication mechanism are studied in this paper, from different angles. The communication mechanism is designed and optimized, and a series of models and optimal design methods are put forward. It has made a positive contribution to the development of the real-time system communication mechanism, and has certain theoretical significance and application value.
【學(xué)位授予單位】：國防科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：TP332

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