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embedded real time systems by kvkk prasad pdf

Abstract

This paper presents a technical vision for future individual traffic. It deals with two different objectives: passenger cars or motorcycles as battery-driven electric vehicles (EVs) and traffic congestion avoidance. On the technical background of our own work we will explain how power supply for recharging the batteries will have to be organized in a distributed fashion, in particular under the assumption that the power is provided through renewable sources such as from wind turbines and solar panels (which are widely dispersed themselves). We will argue that while the unpredictability of local or regional customers in traditional power grid management creates already major problems for network stability (thus for providing the reserve energy needed) these will be greatly amplified by introducing EVs on a large scale, and by integrating renewable energy into the existing power management. In our DEZENT project we have defined and broadly pursued a distributed bottom-up approach for negotiating demand and supply under such circumstances, in an adequate architecture where demand and supply will be negotiated by software agents within 0.5 sec intervals while at the same time the grid stability is guaranteed. Since EVs themselves constitute relevant sources of reserve energy when coming up in large numbers they could be a core instrument for minimizing the stability problem.- Under this innovative perspective we will also discuss a novel distributed algorithm (BeeJamA) based on Swarm Intelligence where the EVs receive directions in due time, in a highly dynamic way before reaching each road intersection. In the absence of global information congestions are avoided and at the same time the travel times of all drivers are "homogenized". Combined with the transition into EV traffic we also could expect a very substantial reduction of pollution thus altogether an enormous ecological and economic progress.

Introduction

Real-time systems are computer systems that monitor, respond to, or control an external environment. This environment is connected to the computer system through sensors, actuators, and other input-output interfaces. It may consist of physical or biological objects of any form and structure. Often humans are part of the connected external world, but a wide range of other natural and artificial objects, as well as animals, are also possible.

The computer system must meet various timing and other constraints that are imposed on it by the real-time behavior of the external world to which it is interfaced. Hence comes the name real time. Another name for many of these systems is reactive systems, because their primary purpose is to respond to or react to signals from their environment. A real-time computer system may be a component of a larger system in which it is embedded; reasonably, such a computer component is called an embedded system.

Applications and examples of real-time systems are ubiquitous and proliferating, appearing as part of our commercial, government, military, medical, educational, and cultural infrastructures. Included are

vehicle systems for automobiles, subways, aircraft, railways, and ships
traffic control for highways, airspace, railway tracks, and shipping lanes
process control for power plants, chemical plants, and consumer products such as soft drinks and beer
medical systems for radiation therapy, patient monitoring, and defibrillation
military uses such as firing weapons, tracking, and command and control
manufacturing systems with robots
telephone, radio, and satellite communications
computer games
multimedia systems that provide text, graphic, audio, and video interfaces
household systems for monitoring and controlling appliances
building managers that control such entities as heat, lights, doors, and elevators