| Networked control system (NCS) has become the mainstream form of the automation industry. In such a system, nodes are networked and interacted with each other according to a communication protocol stack. The distributed infrastructure complexity, communication environment heterogeneity, and control strategy diversity bring great impact on the system performance. This paper proposes a reconfigurable self-organizing protocol stack (RSPS) for nodes in NCS, including the design, implementation and optimization solutions. Full or partial reconfiguration in the protocol stack itself or from the third part provides the network adaptability for application and environment variations.The principle and development process for reconfigurable self-organizing protocol stack are firstly summarised. The advantages of Finite State Machines (FSM) and Petri nets in the protocol design and evaluation process are analyzed. Then, the virturalization technology is shown as an advanced platform-independent solution for the development of RSPS. Besides, as two other key technology to implement RSPS, limits on the existing methods for the code automated management and QoS aware scheduling are pointed out.To meet the requirements and constraints in NCS, a kind of RSPS architecture is proposed. This architecture defines three functional components and relationship with each other:a protocol stack governing the node interactions, a reconfiguration interface support code updating, and a reconfiguration manager determines the new protocol file. Then, a model driven reconfiguration management framework is given to clarified two reconfiguration levels within the RSPS architecture, called parameter-level and code-level reconfiguration. The management framework is the basis of the following RSPS researches.On basis of the Specification and Description Language (SDL), a framework to implementing the dynamic code-level reconfiguration is given. Firstly, a set of SDL models that are mapping with the functions defined in the RSPS architecture are built. Then, a binary coding rule is proposed cope with the states explosion problem, for exploring and reducing the reconfiguration space and generating the C Code. The standard ELF (Executable and Linkable Format) file is employed to construct the protocol configuration file, which guarantees the completeness during code migration and supports dynamic code loading in the target platform. The method of formal testing is given, and a case on Linux platform shows that the SDL framework enables an unambiguous design process and supports easy testing of real reconfiguration capability.A synthetical performance evaluation model for RSPS is proposed with the help of Deterministic and Stochastic Petri Nets (DSPN). The extended DSPN modeling rule is defined for the protocol modeling, and under this concept, the genetic performance sub-models of timing, task interrelation, resource are given. The synthetically DSPN model provide the convenience to get an approximate real performance result by static and dynamic testing, such as the qualified metrics of real time performance, network utilization and efficiency. On the aspect of performance optimization, the self-adaptive scheduling scheme is improved by a combination of neural network (NN) and genetic algorithm (GA). The network stability can be maintained, because the GA scheduler can reconfigures the scheduling table proactively based on the predicted QoS variations, which are captured by an Elman NN.Focusing on the requirement of industrial wireless communication, a prototype design of RSPS based Wireless Sensor Network (RcWSN) is given, which is compatible with the standard IEEE 802.15.4. Under a mesh topology, RcWSN takes advantages in the aspects of real-time performance, adaptability and energy cost. It can adapt to the changes of enviroment or application with the mechanisms of routing and scheudling reconfiguration.Finally, the full text of this article is summarized, the deficiencies are explained and the future of RPS is prospected.
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