| With the development of information technology, the combination of the Internet of things (IOT) technology and agricultural production has formed "smart agriculture". Agricultural Internet of things (AIOT) is the core technology of smart agricultural system. In facility agriculture, AIOT gives full play to the characteristics of intelligent sensing and automatic control, which has greatly promoted the intelligent construction of facility agriculture and effectively improved the production condition of agriculture.AIOT system design is an important stage in the facility agricultural system development life cycle. Defect of the system design phase can be amplified gradually along with the deepening of system development. The formal method is a means of modeling and analyzing the system design based on mathematics. In order to reduce the errors of system design, in this paper the characteristics of AIOT are analyzed, and timed automata theory in formal methods is used in system design to model and validate to ensure the correctness of the system design.The main research contents and innovations of this paper are as follows:(1) Firstly, the modeling verification of AIOT architecture design is studied. It proposes a method of AIOT system architecture design modeling and verification based on timed automata. IOT architecture model is a reference for the IOT system structure design. The existing IOT architecture model has only described the system structure and not provided a means to verify the correctness of the system design. This paper introduces the time automata theory as a basis for AIOT system model and model validation, and thus analyzes the AIOT system architecture design. According to the actual implementation of the AIOT system, the system is divided into perception layer, network layer and application layer. What’s more, each component of these three layers is formally specified to form time automata models of sensing device, performing device, network, on-site control module and cloud IOT service, and finally UPPAAL is used to formally verify the established time automata model.(2) Secondly, the reliability verification of AIOT gateway design is studied. AIOT gateway test method based on timed game automata is proposed. For the control signals and data information coexist in AIOT systems, the non controllable information input will lead to the uncertainty in the system operation. Non controllable and controllable information appear as a game state in the process of transmission. This paper introduces the time game automata to model IOT gateway information transmission process. By analyzing the information transmission method in IOT system, the participants of information transmission and IOT gateway are individually specified to time game automata model, and uploaded data information and issued control signal are analyzed separately. Finally, the model validation tool UPPAAL-TIGA is used to validate IOT gateway for information transmission process.(3) Thirdly, the formal modeling problem of hybrid systems consisting of AIOT is studied. A program of extended time automata is proposed. In this paper, the composite services of AIOT are choosed as study objects. A composite service is made up by a combination of basic services, including both discrete event subsystem and continuous variables subsystems, which make the system hybrid. Aiming at the hybrid modeling problem of the system, the causes are analyzed and the system design is simplified. On this basis the state of time automata are classified, and the states involving input continuous variables are divided separately. Constraint relation and state transition method for this kind of state are designated to form time automata expansion program. Finally, taking AIOT in realistic scenario as an example, extended time automata is used for formal modeling and verification. |
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