Research Of Key Technologies For Cyber Physical Systems Oriented Node Operating System

Traditionally,the development of the physical world is separated from the information world.With the rapid development of computer,communication and control(3C)of information technology,the two worlds are integrating.On the one hand,the physical world is in the process of networking and informatization;on the other hand,the information world is deeply embedded in the physical world,which triggers a feedback from the physical world.In this situation,the concept of the Cyber Physical Systems(CPS)emerges.CPS pay attention to the core problem of the process while physical world is interrogating with the information world,namely,how the continuous physical processes match the discrete information.At present,a heated research in this field mainly focuses on CPS model and CPS technology to support two aspects.Node operating system at the bottom of CPS sensor and actor network is based on direct interaction with the physical processes,which is responsible for an important supporting technology,belonging to CPS.Although there has been some research results of the node operating system in the process of the traditional wireless sensor networks,these systems are not designed for the feature of CPS,nor can meet the application requirements in the field of CPS directly.This paper is doing research and design work for the demands and characteristics of the node operating system for CPS.The main contributions include the following contents:(1)A node operating system architecture to meet the requirements of CPS At present there are some research results of the node operating systems,but these methods in traditional systems are designed for wireless sensor networks,without taking CPS associated physical,interconnection and intelligence requirements into account,thus it is difficult to be applied directly as a supporting technology into CPS field.Based on in-depth research and analysis of CPS system structures and key.attributes,this study proposes a node operating system corresponding relation compatible with CPS features,and presents the relevant research directions and design methods.On this basis,the study puts forward the system structure of a CPS oriented node operating system,analyzes the system architecture,function and design structures and illustrates the functions and design structures of major modules,including hardware abstraction layer,scheduling core,communication protocol stack,memory management module,file system and etc.,which plays an instructive part in the research of the key technology in the node operating system for CPS.(2)A node hybrid programming model to meet flexibility property for CPSThere are more applications for CPS and diverse types of tasks,specifically reflecting task types from event-driven mechanism to multithread-driven mechanism,which offer challenges on the single task programming model in the traditional node operating system.Aiming at the problem,the study proposes an adapter based hybrid programming model.This study deeply analyses the natural relationship of event programming model and multithread programming model,and points out the essential difference between task management modes and stack management modes of each other.This study gives out transformation level and transformation time node of model transformation position and applies an adapter mechanism which realizes integration of different stack management modes of manual stack and automatic stack,so as to realize the hybrid programming model.It can achieve compatibility support with event tasks and thread tasks in the node operating system to meet the requirement of CPS flexibility.(3)A node scheduling algorithm to meet real-time property for CPSThere exists real-time problem in sensor network node operating systems,but this is a core requirement for CPS.Aiming at this problem,the study proposes a new PTS-SRP algorithm which integrates preemption threshold(PT)algorithtm and stack resource protocol(SRP)in node scheduling system.PTS-SRP algorithm establishes assignment relationship between preemption threshold o and SRP resources ceiling?,to solve the matching problem of preemption threshold and parameter,to achieve the integration of limited preemption algorithm and resource access protocol.The study completes real-time schedulability analysis of PTS-SRP algorithm,and gives the corresponding preemption threshold strategy.The result of the experiment tests shows that the real-time task interrupt response number index in single node system and real-time performance in multi-node network of the PTS-SRP algorithm are both better than those mainstreaming node scheduling systems.(4)A node scheduling model to meet adaptability property for CPSAdaptability comes from the requirement of CPS processing multi-type tasks.The scheduling models of most node operating systems are difficult to schedule different kinds of tasks at the same time.The study establishes a hierarchical scheduling model,which can construct different types of tasks and task scheduling algorithms in demand.This study also describes and analyzes the scheduling system structure and scheduling mechanism with parameterization.The scheduling model can be configured to support the hybrid programming model which is proposed in this paper,and it can,also be adjusted by system parameters to achieve other strategic modes of multiple scheduling system types,which can meet the adaptability requirements of CPS node scheduling system.(5)Node data management methods to meet real-time and predictability properties for CPSThe research work in the field of sensor network has gradually shifted from the traditional node communication centered to data storage centered.The various types of application in CPS further enhance this demand.Currently,this change has put forward a challenge to the node operating system which only provides limited data management methods.This study aimed at the problems including poor data management,unable to predict real-time management time in node data management method,and proposes a centralized log-cascading virtual sector mapping algorithm(CLVS).This method helps to solve the delay problem from the change operations of flash blocks through establishing the virtual sector mapping,to solve flash data operation prediction problem through the centralized cascade page log strategy.The study gives the methods of garbage collection mechanism and wear leveling strategies.The results of experiments show that,this method has better real-time performance and more precise predictability in data operations and better performance in garbage recycling and wear leveling,without increasing system load.