Research On Model And Control Technology Of Multi-Agent System For Distributed Control In Process Industry

As the developing direction of industrial production process to large scale, production equipment to complex and controlling task to multi-objective optimization, the process industry presents decentralized and heterogeneous tendency in the production process, and also presents distribution, hierarchy and complexity in function, in time or space as well as in reciprocity. So it is difficult to make the traditional control system to meet the requirements of the modern process industrial control. Therefore, how to keep the control system can make decisions and control independently and coordinate with each other to realize complex process control has become the anxious problem of process control in process industry. For the purpose of this paper, a novel multi-Agent architecture based on the actual control requirements of industrial process control and the needs of the development of production was proposed, and the proposition how to build the hierarchical distributed control multi-Agent system of process industry was also put forward. Research on key issues such as the cooperation mechanism, task scheduling method and task execution strategy was studied, to achieve distributed intelligent control of process industry, which was assigned by task and foundation. The main contents of this paper are as following:Firstly, based on the analysis of independence, union, distribution and intelligent characteristics of the multi-Agent system, a process industry control oriented hierarchical distributed multi-Agent model was constructed and designed. On the top of model is system management Agent and execution grade of model is workshop. Agent, which is consisted of some job-shop scheduling control Agents. The bottom of the model is established by the scene Agent and they realize the interaction of data and information through OPC interface. With the introduction of the concept of Agent group, the domain-based internet model was used to achieve the effective management of the Agent groups, what are distributed on the Ethernet/Intranet and composed of multiple scene Agents and workshop scheduling control Agent. The structure and main function for each individual Agent were designed, a communication structure based on point to point and improved based on Agent-based were adopted to achieve the communication among Agents in this system, and a two coordinated control was taken as the distributed coordinated control mechanism of the whole system. This multi-Agent control model has achieved hierarchical organizational structure, distributed coordination on control, and has a good characteristic of integration, heterogeneity, flexibility and openness.Secondly, to solve the problem of coordination among agents which are belonged to the same Agent group, game theory was introduced to the multi-Agent system for distributed control Agent collaboration. Based on the detailed analysis of basic concepts, collaboration and knowledge of game theory, the collaboration model of multi-Agent was constructed which was based on game theory. Through the improvement of benevolent function by introduction of attenuation factor, the lay siege on the target was paid more attention at beginning of Agents collaboration, and the distance between the targets was taken as the basis of strategy selection after collaboration Agents have maken a certain siege situation on the target, which can speed up the completion of the collaborative task. By using MATLAB, the cooperation mechanism of multi-Agent system was tested through the pursuit-evasion problem. These simulation results indicated that the multi-Agent cooperation mechanism based on improved game theory can be effectively used to cooperation of multi-Agent.Thirdly, in order to solve task scheduling problem of process industry distributed control system and on the basis of task scheduling strategy of multi-Agent system and particle swarm algorithm, task scheduling strategy based on the improved particle swarm algorithm was proposed. Considering the basic particle swarm algorithm has the shortages of premature convergence and the global convergence in actual application, the particle swarm algorithm based on the self-adapting inertia was applied to the task scheduler process of process industry multi-Agent system. Tthrough making linear transform of inertia weights in search process of particle swarm algorithm, dynamic self-adapting inertia was used to improve the performance particle swarm optimization algorithm. Through comparing the simulation results with ant colony system of specific production scheduling in process industry, the effectiveness and superiority of scheduling method were fully substantiated.Fourthly, in order to solve the control strategy of process industry distributed control Agent system, based on analysis of fuzzy PID control and genetic algorithm, the conception was put forward that adaptive genetic algorithm was used to optimize the fuzzy PID parameters, which was taken as control strategy of on-site Agent. By selecting the adaptive function and designing the penalty function, as well as adopting to adjust control parameters of genetic algorithm, the proportionality factor and the quantification factor of fuzzy PID were optimized by genetic algorithm. The control algorithm was validated by MATLAB. Simulation results show that the design algorithm has a better control quality and it can be used as the control strategy to realize intelligent optimization control of process industry process.Fifthly, on the basis of above researches, the detergent manufacturing process control of multi-Agent system structure was constructed. Based on the analysis of component and communication mode of multi-Agent system on JADE, the JADE platform which follows the FIPA standard was chosen as multi-Agent system developing platform. With Java, MATLAB, MCGS, S7-PLC programmable controller and OPC technology, the implement technology of Agent communication, task scheduling method and control system technology for detergent manufacturing were explored, and the specific implement technology were also given.Aiming at the problem of information isolated island in process control system of detergent manufacturing and at the basis of multi-Agent technology of distributed artificial intelligence, the key issues such as organizational structure, coordination mechanism, scheduling algorithm and control strategy, were analyzed and studied systematically in this paper, which was based on distributed control multi-Agent system of process industry. Then, taking detergent manufacturing process control as the application background, the implementation technologies were also analyzed and studied. The researche results can provide the theory and technology function for process industry distributed control, also can provide the engineering design and realization method, and have an important theoretical and practical value.