Examples of Real-Time and Embedded Systems Albert M. K. Cheng Real-Time Systems Laboratory Department of Computer Science University of Houston, TX 77204, USA

An Embedded System or Real-time System Produces correct results in a timely manner. Embedded system computer hardware and software embedded as part of complete device to perform one or a few dedicated functions; often with real-time requirements. Examples: MMDs, PDAs, Cell phones, GPS, etc. What is a real-time system? In a real-time system, the tasks have deadline. Each task is required to finish correctly before its deadline. 2

Motivations and Applications: Automotive Control, Avionics, Medical Systems, and Many Embedded Systems

More Applications: Oil Exploration and Production

Control Systems: Old and New Old: Entire control process is done by mechanical hardware, governed by the mathematics of feedback control. Examples: Mastered cam grinder, Watt governor, Pneumatic process controller. New: Advances in electronics and computer systems lead to energetically isolate components of a controlled mechanical system. Masterless cam grinder, Digital oil production control of pump systems, Fly-by-wire airplane, Drive-by-wire automobile.

Components of a Modern Control and Monitoring System Monitor/Instruments: Signal processing, Energy conversion User(s)/Operator(s) UI D T User Interface Decision and Control System: Computer Hardware, Software, Electronics Target System Under Control: Chemical/Fluid, Electrical, Mechanical, Thermal N Networking and Communication A Actuation: Energy conversion, Power modulation Other Components

Cyber-Physical System (CPS) Tight conjoining of and coordination between computational and physical resources. Significantly enhance the adaptability, autonomy, efficiency, functionality, reliability, safety, and usability of current control systems. Example: An aerospace CPS will respond more quickly (e.g., automatic aircraft collision avoidance), are more precise (e.g., multiple landings in small airports), work in inaccessible environments (e.g., autonomous space exploration), provide large-scale, distributed coordination (e.g., automated air traffic control), are highly efficient (e.g., long-duration space travel), and augment human capabilities (e.g., tele-robotics).

Correctness of Real-Time Control and Monitoring Systems Satisfaction of logical correctness constraints Satisfaction of timing constraints

Design and Implementation Issues Control and monitoring systems: old and new Model of an embedded/real-time system Scheduling real-time tasks Rate-monotonic scheduler, EDF, LLF Scheduling constraints Multiprocessor scheduling Identical, uniform, heterogeneous multiprocessors Specification, verification, and debugging