6 01 Fall Semester 2007 Lecture 1 Notes 1 MASSACHVSETTS INSTITVTE OF TECHNOLOGY Department of Electrical Engineering and Computer Science 6 01 Introduction to EECS I Fall Semester 2007 Lecture 1 Notes Goals for 6 01 We have a number of goals for this course Our primary goal is to enhance your ability to solve complex problems by strengthening your skill in the most pervasive strategy for dealing with complexity using abstraction and modularity We will examine the use of abstraction and modularity in a number of contexts associated with problems in electrical engineering EE and computer science CS as we hope to help you develop a more fundamental understanding of abstraction and modularity We also hope that you will see more than just the similarities in broad perspective but will also develop skills in using several specific abstraction strategies that have persisted in importance To accomplish our primary goal we will study how to analyze and design systems that interact with and attempt to control an external environment Such systems include everything from low level controllers like heat regulators or cardiac pacemakers to medium level systems like automated navigation or virtual surgery to high level systems that provide more natural humancomputer interfaces Our second goal is for you to learn that making mathematical models of real systems can help in the design and analysis of those systems and to give you practice with building those models In particular we hope you will develop insight in to the difficult step of deciding which aspects of the real world are important to the problem being solved and then how to model in ways that give insight into the problem We also hope to engage you more actively in the educational process Most of the work of this course will not be like typical problems from the end of a chapter You will work individually and in pairs to solve problems that are deeper and more open ended There will not be a unique right answer Argument explanation and justification of approach will be more important than the answer We hope to expose you to the ubiquity of trade offs in engineering design It is rare that a single approach will be best in every dimension some will excel in one way others in a different way Deciding how to make such trade offs is a crucial part of engineering Another way in which we hope to engage you in the material is by having many of you return to the course as a lab assistant Having a large number of lab assistants in the course means that you can be given more interesting open ended design problems because there will be staff readily available to make sure you do not get stuck Even more important the lab assistants will question you as you go to challenge your understanding and help you see and evaluate a variety of approaches This Socratic method has proven to be of great intellectual value to both classroom students and lab assistants Finally of course we have the more typical goals of teaching exciting and important basic material from electrical engineering and computer science including modern software engineering linear systems analysis electronic circuits and estimation and decision making This material all has an internal elegance and beauty as well as crucial role in building modern EE and CS systems 6 01 Fall Semester 2007 Lecture 1 Notes 2 Modularity abstraction and modeling Whether proving a theorem by building up from lemmas to basic theorems to more specialized results or designing a circuit by building up from components to modules to complex processors or designing a software system by building up from generic procedures to classes to class libraries humans deal with complexity by exploiting the power of abstraction and modularity And this is because there is only so much complexity a single person can hold in their head at a time Modularity is the idea of building components that can be re used and abstraction is the idea that after constructing a module be it software or circuits or gears most of the details of the module construction can be ignored and a simpler description used for module interaction the module computes the square root or doubles the voltage or changes the direction of motion One can move up a level of abstraction and construct a new module by putting together several previously built modules thinking only of their abstract descriptions and not their implementations This process gives one the ability to construct systems with complexity far beyond what would be possible if it were necessary to understand each component in detail Any module can be described in a large number of ways We might describe the circuitry in a digital watch in terms of how it behaves as a clock and a stopwatch or in terms of voltages and currents within the circuit or in terms of the heat produced at different parts of the circuitry Each of these is a different model of the watch Different models will be appropriate for different tasks there is no single correct model The primary theme of this course will be to learn about different methods for building modules out of primitives and of building different abstract models of them so that we can analyze or predict their behavior and so we can recombine them into even more complex systems The same fundamental principles will apply to software to control systems and to circuits Example problem Imagine that you needed to make a robot that would roll up close to a light bulb and stop a fixed distance from it The first question is how can we get electrical signals to relate to the physical phenomena of light readings and robot wheel rotations There is a whole part of electrical engineering related to the design of physical devices that that connect to the physical world in such a way that some electrical property of the device relates to a physical process in the world For example a light sensitive resistor photoresistor is a sensor whose resistance changes depending on light intensity a motor is an effector whose rotor speed is related to the voltage across its two terminals In this course we will not examine the detailed physics of sensors and effectors but will concentrate on ways of designing systems that use sensors and effectors to perform both simple and more complicated tasks To get a robot to stop in front of a light bulb the problem will be to find a way to connect the photoresistor to the motor so that the robot will stop at an appropriate distance from the bulb An
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