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1、毕业设计（论文） 外文文献翻译文献、资料中文题目：CAN总线系统的实时对象调用 文献、资料英文题目:Invocation of Real-Time Objects in a CAN Bus-System文献、资料来源： 文献、资料发表（出版）日期：院（部）：专 业：班 級:姓 名：学 号：指导教师: 翻译日期:2017. 02. 14Invocation of Real-Time Objects in a CAN Bus-SystemAbstractThe paper focuses on method invocation of real-time objects in a CAN-base
2、d distributed real-time system. A simple object model is introduced，which allows the convenient modelling of hardware and software components. Related to the object model，two issues are discussed. Firstly，a model is introduced which allows to form and address object groups. This reflects a basic nee
3、d in a real-time system to distribute information to multiple clients efficiently. Secondly，we discuss an approach to express timing requirements for object invocations. To achieve distributed consensus on communication resource access，an EDF-like approach is introduced，which takes advantage of know
4、ledge about deadlines，the number of remaining communication activities，and the remaining worst-case execution time for the invoked method at each point of time.1. IntroductionFuture computer systems will，to a large extent，monitor and control real-world processes. This results in an inevitable demand
5、 for timeliness and reliability. Distributed systems which inherently provide immunity against single failures are an adequate architecture to meet the goal of reliability. Additionally, because realworld applications often require the spatially distributed control of electromechanical components，a
6、distributed system architecture brings computing power to the points where it is needed. The availability of inexpensive yet powerful microcontrollers supports a distributed solution. This results in a system model which is composed from smart components implementing the instrumentation interface to
7、 the real world comprising sensors and actuators. A convenient way to model such an environment is to use an object-based approach where objects encapsulate all kinds of entities necessary to control a physical process.We can identify at least two layers in systems interacting with the real world. A
8、 lower responsive system level tightly controlling the sensor/actuator interface to the world and a higher system level responsible for interpretation and evaluation of the perception of the world as communicated by the instrumentation interface. In this layer，higher level decisions are performed. A
9、lthough these different levels have different requirements concerning responsiveness，they are sometimes not separated clearly simply because of the hardware architecture. We concentrate on the lower system level and describe an object model which is motivated by a system structure which relies on a
10、modular design and independent computing resources for the components of the instrumentation interface. Rather than having a central powerful processor in which electromechanical components are only modelled as objects from which control signals are generated, the electromechanical components are ob
11、jects themselves powered by inexpensive microcontrollers. The objects of this layer have a well defined interface to be easily controlled by a higher level instance which can exploit this abstraction rather than dealing with low level control signals.The hardware modules are connected by a field-bus
12、. We choose the CAN-bus (CAN: Controller Area Network), developed by BOSCH28 because it provides advanced technical features and represents an emerging standard with a wide applicability. Moreover， popular microcontrollers are available with an on-chip CAN controller. CAN is a shared bus designed to
13、 connect control systems in a spatially restricted area like cars, robots，tool machines，and other automotive or industrial automation applications. It is targeted to operate in a noisy environment with speeds of up to 1 Mbit/sec，exchanging small real-time control messages. We use the CAN message for
14、mat to uniformly invoke methods on our objects. This allows a transparent object invocation in the sense that an invoking object must not know where the invoked object resides in the system. Additionally，we can address groups of objects with a single CAN message.As a common resource，the communicatio
15、n medium has to be shared by all computing nodes. Access to the medium has to be scheduled in a way that distributed computations meet their deadlines in spite of competition for the communication line. Since the scheduling of the bus cannot be based on local decisions，a distributed consensus about
16、the bus reservation has to be achieved. Clearly，this is only a special case of the more general problem to schedule a cooperative distributed computation.There exist several alternative approaches to solve this problem based on the assumptions about the behaviour of the system and the environment. The first approach, known as time-triggered approach 18，21，19 assumes a complete knowledge of all future a
