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1、,Computer Architecture Trends,Present proposals for future billion-transistor computers: Desktop uniprocessors for technical applications Multiprocessor servers for transaction processing Large continuous data-processing capability Future embedded system computers: Harsh environment tolerance; tempe
2、rature, vibration, radiation Low power dissipation, power down modes On-chip input-output units, communication and memory Predictable behavior, support for concurrency,Technology basis,Characteristics of embedded control systems,Variety of types of functionality/domains Hierarchical structure Distri
3、buted systems Environment constraints RT constraints ET and TT, parallelism Roughness Resource constrained implementation Dependability,Why not a single processor?,Example application: stability control,Reklamfilm www.esceducation.org,Example application: stability control,Example application: vehic
4、le stability control,ESP follow up; summarizing characteristics,Several modes of operation Multiple input, multiple output Availability critical (graceful degradation) Hierarchical and cascaded control Safety critical, real-time operation Redundancy in hardware (sensors, actuators, processors), info
5、rmation and algorithms Upgrades? Buy or make components? Driver vs. computer control decides? How to define a suitable architecture? How to organize the development?,Ingredients in vehicle dynamics control,Longitudinal control Lateral control Roll, pitch and yaw Basic force generation between vehicl
6、e and road takes place in contact patches of the four tires: - Road surface determines available friction - These forces provide feedback (“feel”) to the driver about vehicle behavior and road conditions.,Ingredients in vehicle dynamics control,Available actuators: Wheel acceleration and deceleratio
7、n - Wheel slip: Vehicle speed vs. wheel speed Anti-blocking system (ABS) Anti-spin (or traction) control Wheel steering Dampers Active body control (ABC) Longitudinal control: Cruise and adaptive cruise control Lateral control Stability (yaw) control,Characteristics of embedded control systems,Varie
8、ty of types of functionality/domains Hierarchical structure Distributed systems Environment constraints RT constraints ET and TT, parallelism Roughness Resource constrained implementation Dependability,Example control system hierarchy,Hierarchy: in applications and platform,Characteristics of embedd
9、ed control systems,Variety of types of functionality/domains Hierarchical structure Distributed systems Environment constraints RT constraints ET and TT, parallelism Roughness Resource constrained implementation Dependability,A view of a modern car,Distributed systems,Definition? Dimensions? Benefit
10、s? What are the problems (not only benefit)?,What is a distributed system?,A set of networked nodes, cooperating to achieve a common goal (Sloman&Kramer, 1988). Distribution dimensions: hardware, data & control. Enslow, 1978 A loosely coupled system - as opposed to tightly coupled,Loosely and tightl
11、y coupled systems,Two categories of MIMD systems “Distributed computers“ - loosely coupled Communication through messages Serial communication with different topologies Examples: Ethernet and CAN “Multiprocessors“ - tightly coupled Communication through read/writes to shared memory “Control signals“
12、 interrupts High bandwidth/parallel communication Examples: VME, ISA, PCI, .,Why distributed systems?,Cable reduction Modularity mechatronic components Local capabilities, e.g. diagnostics Shared resources and information Functional Integration Reliability and Availability (reduced cabling, no. of c
13、onnectors) Resulting in reduced development and production efforts, and enabling reuse cost reduction!,A mechatronic module: Scania diesel engine and controller,Engine ECU tasks: control of engine, fan, alternator, engine brake, turbo, and the EGR valve + CAN communication, + diagnostics, ,A view of
14、 a modern car,Which nodes are involved in vehicle stability control?,Abbreviations,Distributed systems problem and challenges,Mapping Characteristics which lead to problems Benefits? What are the problems (not only benefit)? and some remedies,Mapping related terms, Assignment in space and in time Al
15、location Scheduling per resource (nodes & communication),Essential characteristics and problems with distributed systems, True parallelism Communication links subject to errors, transient or permanent Subsystem failures: node, communication Implications: - Time varying end to end delays, asynchronis
16、m - Consistency problems Design issues: - Error detection & handling, end to end resource management - The fundamental mapping problem/levels of decentralization,Distributed state variables, M1, M2, M3 = the system state; is it consistent?,When is the state required to be consistent? Consistency in the precense of faults? Idempotent messages? m, m - m,Clock synchronization,Communication protocols,Open systems interconnection model,X-by-wire; closely related to distributed control,
