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Robotics! Student Guide Version 1.4 Note regarding the accuracy of this text: Accurate content is of the utmost importance to the authors and editors of the Stamps in Class texts. If you find any error or subject that needs clarification, please report it to stampsinclass@parallaxinc.com. Warranty Parallax warrants its products against defects in materials and workmanship for a period of 90 days from receipt of product. If you discover a defect, Parallax will, at its option, repair or replace the merchandise, or refund the purchase price. Before returning the product to Parallax, call for a Return Merchandise Authorization (RMA) number. Write the RMA number on the outside of the box used to return the merchandise to Parallax. Please enclose the following along with the returned merchandise: your name, telephone number, shipping address, and a description of the problem. We will return your product or its replacement using the same shipping method used to ship the product to Parallax. 14-Day Money Back Guarantee If, within 14 days of having received your product, you find that it does not suit your needs, you may return it for a full refund. Parallax will refund the purchase price of the product, excluding shipping/handling costs. This guarantee is void if the product has been altered or damaged. Copyrights and Trademarks This documentation is copyright 2000 by Parallax, Inc. BASIC Stamp is a registered trademark of Parallax, Inc. If you decide to use the name BASIC Stamp on your web page or in printed material, you must state: "BASIC Stamp is a registered trademark of Parallax, Inc." Other brand and product names are trademarks or registered trademarks of their respective holders. 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Access information is shown below: E-mail: Web: stampsinclass@parallaxinc.com http://www.parallaxinc.com and http://www.stampsinclass.com Internet BASIC Stamp Discussion Lists We maintain two e-mail discussion lists for people interested in BASIC Stamps (subscribe at http://www.parallaxinc.com under the technical support section). The BASIC Stamp list server includes engineers, hobbyists, and enthusiasts. The list works like this: lots of people subscribe to the list, and then all questions and answers sent to the list are distributed to all subscribers. It’s a fun, fast, and free way to discuss BASIC Stamp issues and get answers to technical questions. This list generates about 40 messages per day. The Stamps in Class list is for students and educators who wish to share educational ideas (subscribe at http://www.stampsinclass.com under the discuss/e-mail section). This list works the same way the BASIC Stamp list server does, and it currently generates about five messages per day. Contents Table of Contents Preface .......................................................................................................................................... 1 Audience and Teacher’s Guides .................................................................................................................................. 2 Copyright and Reproduction ...................................................................................................................................... 3 Typographical Conventions......................................................................................................................................... 3 Robotics! Contributors................................................................................................................................................ 4 Chapter #1: Assembling and Testing Your Boe-Bot ...........................................................................5 Systems, Subsystems and Robotics Competitions .................................................................................................. 5 Assemble, Test, Modify, Test, Assemble, Test… ......................................................................................................... 6 Boe-Bot Hardware ....................................................................................................................................................... 6 Activity #1: Testing PC - BASIC Stamp Communication.......................................................................................... 8 Activity #2: Testing the Servos..................................................................................................................................17 Activity #3: Modifying the Servos.............................................................................................................................27 Activity #4: Centering the Servos – Calibration in Software...............................................................................34 Activity #5: Boe-Bot Construction ...........................................................................................................................35 Activity #6: Navigation and More Servo Tuning in Software ...............................................................................41 Summary and Applications........................................................................................................................................45 Questions and Projects..............................................................................................................................................47 Chapter #2: Programming the Boe-Bot to Go Places ...................................................................... 51 Converting Instructions to Motion ..........................................................................................................................51 Activity #1: Low Battery Indicator............................................................................................................................52 Activity #2: Controlling Distance ..............................................................................................................................56 Activity #3: Maneuvers – Making Turns ...................................................................................................................61 Activity #4: Maneuvers – Ramping ...........................................................................................................................63 Activity #5: Remembering Long Lists Using EEPROM ............................................................................................65 Activity #6: Simplify Navigation with Subroutines.................................................................................................70 Activity #7: All Together Now ....................................................................................................................................72 Summary and Applications........................................................................................................................................78 Questions and Projects..............................................................................................................................................79 Chapter #3: Tactile Navigation with Whiskers................................................................................. 83 Tactile Navigation .......................................................................................................................................................83 Activity #1: Building and Testing the Whiskers.......................................................................................................83 Activity #2: Navigation With Whiskers.....................................................................................................................90 Activity #3: Looking at Multiple Inputs as Binary Numbers ..................................................................................94 Page i Contents Activity #4: Artificial Intelligence and Deciding When You’re Stuck...................................................................98 Summary and Applications .....................................................................................................................................103 Questions and Projects............................................................................................................................................104 Chapter #4: Light Sensitive Navigation with Photoresistors .......................................................... 107 Is Your Boe-Bot a Photophile or a Photophobe?................................................................................................107 Activity #1: Building and Testing Photosensitive Eyes.........................................................................................108 Activity #2: A Light Compass ...................................................................................................................................112 Activity #3: Follow the Light!...................................................................................................................................115 Activity #4: Line Following .......................................................................................................................................118 Summary and Applications .....................................................................................................................................122 Questions and Projects............................................................................................................................................123 Chapter #5: Object Detection Using Infrared ............................................................................... 125 Using Infrared Headlights to See the Road ..........................................................................................................125 Infrared Headlights ..................................................................................................................................................125 The Freqout Trick......................................................................................................................................................126 Activity #1: Building and Testing the New IR Transmitter/Detector .................................................................127 Activity #2: Object Detection and Avoidance .......................................................................................................130 Activity #3: Navigating by the Numbers in Real-Time .........................................................................................134 Summary and Applications .....................................................................................................................................138 Questions and Projects............................................................................................................................................140 Chapter #6: Determining Distance Using Frequency Sweep .......................................................... 143 What’s a Frequency Sweep? ...................................................................................................................................143 Activity #1: Testing the Frequency Sweep ............................................................................................................143 Activity #2: The Drop-off Detector........................................................................................................................150 Activity #3: Boe-Bot Shadow Vehicle ....................................................................................................................155 Summary and Applications .....................................................................................................................................161 Questions and Projects............................................................................................................................................163 Appendix A: Boe-Bot Parts Lists and Sources............................................................................... 165 Appendix B: PC to Stamp Communication Trouble-Shooting......................................................... 171 Appendix C: PBASIC Quick Reference .......................................................................................... 173 Appendix D: Building Servo Ports on the Rev A Board of Education ............................................... 181 Appendix E: Board of Education Rev A Voltage Regulator Upgrade Kit ........................................... 185 Page ii Contents Appendix F: Breadboarding Rules ................................................................................................ 187 Appendix G: Resistor Color Codes ............................................................................................... 189 Appendix H: Tuning IR Distance Detection.................................................................................... 191 Appendix I: Boe-Bot Competition Maze Rules............................................................................... 197 Page iii Preface Preface Robots are used in the auto, medical, and manufacturing industries, and of course, in science fiction films. Building and programming a robot is a combination of mechanics, electronics, and problem solving. What you're about to experience with the Boe-Bot will be relevant to realistic applications using robotic control, the only difference being the size and sophistication. The electronic control principles, source code, and circuits you will use are very similar (and sometimes identical) to industrial applications developed by electronic engineers. The word "robot" first appeared in a Czechoslovakian satirical play Rossum's Universal Robots by Karel Capek in 1920. Robots in this play tended to be human-like. From this point it seemed that any good science fiction story would involve them revolting against human authority, which requires intelligence. This changed when General Motors installed the first robots in its manufacturing plant in 1961. For science fiction or manufacturing, intelligence is only installed in a robot through programming. This series of experiments will introduce you to basic robotic concepts using the Board of Education Robot (hereafter the "Boe-Bot"). The experiments will begin with construction of the Boe-Bot. After that, we'll be programming the Boe-Bot for basic maneuvers, and proceed to interface sensors that will allow the robot to react to its surroundings. The goal of this text is to show students how easy it is to become interested in and excited about the fields of engineering, mechatronics, and software development as they design, construct and program an autonomous robot. The Boe-Bot provides students with a project area to build and customize their own mechanical, electrical, and programming projects. The use of a robot to introduce microcontroller circuits and interfacing is ideal since the outputs are almost entirely visible and easy to customize. The Board of Education may be taken off of the Boe-Bot chassis and used for other Stamps in Class curriculum experiments. This portability saves the class from having to purchase another set of hardware, which significantly reduces the cost of exploring robotics. The Board of Education Rev A was not originally designed for use on a robot. The Boe-Bot was created in response to customer demand, so you will notice one or two work-arounds that wouldn't exist if a robot had been considered when the Board of Education was first conceived. Specifically, the servos use the unregulated 6 V power supply from Vin instead of regulated 5 V power from Vdd. In addition, a 3300 µF capacitor is placed across Vdd and Vss. This prevents brownout conditions and spontaneous BASIC Stamp 2 resets caused by peak servo current draws. An older Rev A Board of Education may also need to have its voltage regulator swapped out for the new LM2940 lowdropout regulator. Details for this are shown in Appendix E, and the replacement parts are free from Parallax. Robotics! Version 1.4 • Page 1 Preface The Board of Education Rev B has been modified to lend itself better to robotics applications without compromising the other four Stamps in Class series of experiments. Larger onboard capacitors connected to the Rev B’s LM2940 voltage regulator eliminate the need for the 3300 µF capacitor used with the Rev A. Four servo ports have been added enabling the use of four servos without taking up any space on the breadboard prototyping area. Each port has a dedicated I/O line (P12, P13, P14, or P15 depending on the port), and each can be used for controlling a servo. Each servo supply is still tied to Vin, the unregulated 6 V from the battery pack, so use of a higher voltage supply is discouraged due to its tendency to overwork the servos. Some of the other components on the Board of Education Rev B have been moved slightly, such as the DB9 serial port connector and the 20-socket app-mod connector. Also, the Vdd socket on the 20-socket app-mod connector now draws from the BASIC Stamp’s voltage regulator while the Vdd sockets above the breadboard still draw from the BOE’s voltage regulator. For the Stamps in Class curriculum, use only the Vdd sockets above the breadboard on the Board of Education. The Robotics curriculum will be revised and updated based on feedback from students and educators. If you would like to author an addition to this curriculum, or have ideas for improvements, please send them to stampsinclass@parallaxinc.com. We'll do our best to integrate your ideas and assist you with whatever technical support, sales support, or on-site training you need. If we accept your Boe-Bot project, we'll send you a free Boe-Bot. Audience and Teacher’s Guide The Robotics curriculum was created for ages 17+ as a subsequent text to the “What’s a Microcontroller?” guide. Like all Stamps in Class curriculum, this series of experiments teaches new techniques and circuits with minimal overlap between the other texts. The general topics introduced in this series are: basic Boe-Bot navigation under program control, navigation based on a variety of sensor inputs, navigation using feedback and various control techniques, and navigation using programmed artificial intelligence. Each topic is addressed in an introductory format designed to impart a conceptual understanding along with some hands-on experience. Those who intend to delve further into industrial technology, electronics or robotics are likely to benefit significantly from initial experiences with these topics. Experts in their field independently author each set of Stamps in Class experiments, and they are provided leeway in terms of format. As a result, the depth and availability of teachers’ guides varies. Please contact Parallax, Inc. if you have any questions. If you are interested in contributing material to the Stamps in Class series, please submit your proposal to stampsinclass@parallaxinc.com. Page 2 • Robotics! Version 1.4 Preface Copyright and Reproduction Stamps in Class curriculum is copyright  Parallax 2000. Parallax grants every person conditional rights to download, duplicate, and distribute this text without our permission. The condition is that this text or any portion thereof, should not be duplicated for commercial use resulting in expenses to the user beyond the marginal cost of printing. That is, nobody should profit from duplication of this text. Preferably, duplication would have no expense to the student. Any educational institution wishing to produce duplicates for its students may do so without our permission. This text is also available in printed format from Parallax. Because we print the text in volume, the consumer price is often less than typical xerographic duplication charges. This text may be translated to any other language with prior permission of Parallax, Inc. Typographical Conventions q Checklist instruction. The square box indicates a “how to” instruction. These instructions should be followed sequentially, like a checklist, through each activity in this text. ü TIP Pay attention to and follow these instructions. They will make the activities easier and save time. FYI This box contains useful information. ! Caution: follow these instructions, or you may end up damaging your hardware. ' PBASIC Program Listings. ' PBASIC excerpt from a program listing. This kind of excerpt ' always follows a paragraph of text explaining what it does ' and how it works. PBASIC code in a paragraph of text takes the form of: command argument1, argument2, etc. Note that the command is not italicized, but its arguments are. Robotics! Version 1.4 • Page 3 Preface Robotics! Contributors Chuck Schoeffler, Ph.D., authored portions of the v1.2 text in conjunction with Parallax, Inc. At that time, Dr Schoeffler was a professor at University of Idaho's Industrial Technology Education department. He designed the original Board of Education Robot (Boe-Bot) shown here along with many similar robot derivatives with unique functions. After several revisions, Chuck's design was adopted as the basis of the Parallax Boe-Bot that is used in this Text. Russ Miller of Parallax designed the Boe-Bot based on this prototype. Andrew Lindsay, Parallax Chief Roboticist, wrote the majority of the v1.3 text with three goals in mind. First, support all activities in the text with carefully written “how to” instructions. Second, expose the reader and student to new circuit, programming, engineering and robotic concepts in each chapter. Third, ensure that the experiments can be performed with a high degree of success using either the Rev A or Rev B Board of Education. Parallax 2000 summer intern, Branden Gunn, assisted in the illustration of this revision. Thanks to Dale Kretzer for editorial review, which was incorporated into v1.4. Thanks also to the following Stamps in Class e-group participants for their input: Richard Breen, Robert Ang, Dwayne Tunnell, Marc Pierloz, and Nagi Babu. These participants submitted one or more of the following: error corrections, useful editorial suggestions, or new material. Error corrections and many editorial suggestions were incorporated into this revision. Some new material, including alternate low battery indicator activities and extra mechanical exercises, will appear in version 1.5. If you have suggestions, think you found a mistake, or would like to contribute an activity or chapter to forthcoming Robotics! v1.5 or More Robotics! texts, contact us at stampsinclass@parallaxinc.com. Subscribe and stay tuned to the Stamps in Class e-group for the latest in free hardware offers for Robotics! contributions. See the Internet BASIC Stamp Discussion Lists section just before the Table of Contents for information on how to subscribe. Every person who works at Parallax, Inc. has in some way contributed to Stamps in Class. A special thanks to the entire Parallax team for everything they’ve done to make the Stamps in Class program a success. Page 4 • Robotics! Version 1.4