Stiquito Controlled!: Making a Truly Autonomous Robot / Edition 1 available in Paperback
About the Author
JAMES M. CONRAD, PhD, is currently a professor for the Electrical and Computer Engineering Department at the University of North Carolina at Charlotte. Jim has worked with IBM, Ericsson/Sony Ericsson, and BPM Technologies. He is a senior member of the IEEE, member of the Project Management Institute and IEEE Computer Society, and board member of the IEEE Computer Society Press operating committee. He is the author of three books on autonomous robotics and has written numerous journal articles, conference papers, and technical papers.
Read an Excerpt
Stiquito ControlledMaking a Truly Autonomous Robot
By James M. Conrad
John Wiley & SonsCopyright © 2005 IEEE Computer Society
All right reserved.
Chapter OneAn Introduction to Robotics and Stiquito
Welcome to the wonderful world of robotics and embedded systems! This third book in the Stiquito series will give you a unique opportunity to learn about these fields in a way that has not been offered before. This book may also be the first affordable educational book to describe an autonomous robot and include the robot with the book! This book will provide you with the skills and parts to build a very small robot. It also has a radical feature not seen in many books currently on the market (if any). We have designed and populated a printed circuit board for attaching to the top of the Stiquito robot. This board contains a microcontroller that drives the legs of your Stiquito robot. This circuit board is the result of several iterations of design and testing by many people.
The star of this book is Stiquito-a small, inexpensive hexapod (six-legged) robot. Universities, high schools, and hobbyists have used Stiquito since 1992. It is unique, not only because it is so inexpensive, but also because its applications are countless. Some examples of uses of Stiquito include the following (with additional sensors and programming):
Light following or avoidance Object detection using infrared or sonar Generation of sound or music using a small speaker Swarm behavior
This chapter will present an overview of robotics, the origin of Stiquito, and suggestions for how to proceed with reading the book and building the kit.
First, Some Words of Caution
This warning will be given frequently, but it is one that all potential builders must heed. Building the robot in this kit requires certain skills in order to produce a good working robot. These hobby-building skills include:
Tying thin metal wires into knots Cutting and sanding small lengths (4 mm) of aluminum tubing Threading the wire through the tubing Crimping the aluminum tubing with pliers Patiently following instructions
The project requires two to four hours to complete.
The field of robotics means different things to different people. Many conjure up images of R2D2- or C-3PO-like devices from the Star Wars movies. Still others think of the character Data from the TV show Star Trek: The Next Generation. Few think of vehicles or even manufacturing devices, yet robots are predominantly used in these areas. Our definition of a robotic device is: any electromechanical device that is given a set of instructions from humans, and repeatedly carries out those instructions until instructed to stop. Based on this definition, building and programming a toy car to follow a strip of black tape on the floor is an example of a robotic device, but building and driving a radio-controlled toy car is not. Machines requiring continuous human control like battle-bots or R/C cars are not really robots, due to their lack of autonomy.
The term "robot" was created by Karel Capek, a Czechoslovakian playwright. In his 1921 play, R. U. R. (Rossum's Universal Robots) , humans create mechanical devices to serve as workers. The robots turn on their creators, thus setting up years of human-versus-machine conflicts.
The term "robotics" was first coined by science fiction author Isaac Asimov in his 1942 short story "Runaround" . Asimov can be considered to be the biggest fan of robotics; he wrote more than 400 books in his lifetime, many of them about or including robots. His most famous and most often cited writing is his "Three Laws of Robotics," which he first introduced in "Runaround." These laws describe three fundamental rules that robots must follow in order to operate without harming their human creators. The laws are:
1. A robot may not injure a human being, or, through inaction, allow a human being to come to harm. 2. A robot must obey the orders given to it by human beings, except where such orders would conflict with the First Law. 3. A robot must protect its own existence as long as such protection does not conflict with the First and Second Laws.
These laws provide an excellent framework for all current and future robotic devices.
There are many different types of robots. The classical robots depicted in science fiction books, movies, and television shows are typically walking, talking humanoid devices. However, the most useful and prevalent robot in use in the United States is the industrial arm robot used in manufacturing. These robotic devices precisely carry out repetitive and sometimes dangerous work. Unlike human workers, they do not need coffee breaks, health plans, or vacations (but they do need maintenance and the occasional sick day). You may have seen an example of these robotic arms in auto maker commercials in which an automobile body is welded and painted. Figure 1.1 shows an example of a small robotic arm manufactured by EPSON Robots.
Another type of robot used in industry is the autonomous wheeled vehicle. Wheeled vehicle robots are used for surveillance or to deliver goods, mail, or other supplies. These robots follow a signal embedded in the floor, rely on preprogrammed moves, or guide themselves using cameras and programmed floor plans. They usually have object-avoidance hardware and software. An example of an autonomous wheeled robot, shown in Figure 1.2, is the Aethon Tug . This device attaches to a cart and travels through a hospital's hallways, delivering the cart and its contents to a programmed destination.
Although interest in walking robots is increasing, their use in industry is very limited. Still, walking robots have been popular in the "entertainment" market. Walking robots have advantages over wheeled robots when traversing uneven terrain. Two recent entertainment robotic "dogs" are the Tiger/Silverlit i-Cybie (retailing for $200) and the Sony Aibo (retailing for $1600). The i-Cybie (Figure 1.3) was not successful in the market and was discontinued, but has a devoted following. It has a distinct feature of being the lowest-priced programmable entertainment robot. Sony has now produced three generations of the Aibo. They also sell a development kit for reprogramming the robot.
Most walking robots do not take on a true biological means of propulsion, defined as the use of contracting and relaxing muscle fiber bundles. The means of propulsion for most walking robots is either pneumatic or motor-driven. True muscle-like propulsion in inexpensive hobby and educational robots did not exist until recently. A new material, Flexinol(r), is used to emulate the operation of a muscle. Flexinol(r) has the properties of contracting when heated, then returning to its original size when cooled. An opposable force is needed to stretch the Flexinol(r) back to its original size. This new material has spawned a plethora of new small walking robots that originally could not be built with motors. Although several of these robots were designed in the early 1990s, one of them has gained international prominence because of its low cost. This robot is called Stiquito.
In the early 1990s, Dr. Jonathan Mills was looking for a robotic platform to test his research on analog logic. Most platforms were prohibitively expensive, especially for a young assistant professor with limited research money. Since "necessity is the mother of invention," Dr. Mills set out to design his own inexpensive robot. He chose four basic materials with which to build his designs:
1. For propulsion, he selected nitinol (specifically, Flexinol(r) from Dynalloy, Inc.). This material would provide a "muscle-like" reaction for his circuitry, and would closely mimic biological actions. More detail on Flexinol(r) is provided in Chapter 4 and other sources . 2. For a counter-force to the Flexinol(r), he selected music wire from K & S Engineering. The wire could serve as a force to stretch the Flexinol(r) back to its original length and provide support for the robot. 3. For the body of the robot, he selected 1/8" square plastic rod from Plastruct, Inc. The plastic is easy to cut, drill, and glue. It also has relatively good heat-resistive properties. 4. For leg support, body support, and attachment of Flexinol(r) to plastic he chose aluminum tubing from K & S Engineering.
Dr. Mills experimented with various designs, from a tiny four-legged robot, two inches long, to a six-floppy-legged, four-inch long robot. Through this experimentation, he found that the best movement of the robots was realized when the Flexinol(r) was parallel to the ground and the leg part touching the ground was perpendicular to the ground.
The immediate predecessor to Stiquito was Sticky, a large hexapod robot. Sticky is 9" long by 5" wide by 3" high. It contains Flexinol(r) wires inside aluminum tubes, which are used primarily for support. Sticky can take 1.5 cm steps, and each leg had two degrees of freedom. Two degrees of freedom means that Flexinol(r) wire is used to pull the legs back (first degree) as well as raise the legs (second degree).
Sticky was not cost-effective, so Dr. Mills used the concepts of earlier robots with the hexapod design of Sticky to create Stiquito (which means 'Tittle Sticky"). Stiquito was originally designed for only one degree of freedom, but has a very low cost. Two years later, Dr. Mills designed a larger version of Stiquito, called Stiquito II, which had two degrees of freedom . A picture of Stiquito II is shown in Figure 1.4.
At about the same time that Dr. Mills was experimenting with these legged robots, Roger Gilbertson of Mondotronics and Mark Tilden of Los Alamos Labs were also experimenting with Flexinol(r). Gilbertson and Tilden's robots are described in the first Stiquito book .
The original Stiquito kit included in Stiquito: Advanced Experiments  and Stiquito for Beginners  relied on aluminum crimps for anchoring the Flexinol(r) to the legs and body. Through experimentation and user comments, we have changed the assembly procedure to now include screws. This new Stiquito kit is named "Stiquito Controlled."
The Stiquito Controlled Kit
The kit that is included with this book has enough materials to make one Stiquito robot, although there are enough extra components in case you make a few errors while building the robot. The most important thing to remember when building this kit is that Stiquito is a hobby kit; it requires hobby-building skills, like cutting, sanding, soldering, and working with very small parts. For example, in one of the steps, you will need to tie a knot with the Flexinol(r) wire. Flexinol(r) is very much like thread, and it is very difficult to tie a knot with it. However, if you have time and patience (and after some practice), you will soon be able to tie knots like a professional.
The kit that is included with this book is a simplification of the original Stiquito described in Jonathan Mills' Technical Report  and offered as a kit from Indiana University. In your kit, the plastic Stiquito body has been premolded, so now you no longer have to cut, glue, and drill the plastic rod to make the body. The addition of screws also makes it easier to build and provides the perfect interface to the printed circuit board.
Remember that building Stiquito is not like a Lego(r) project. This is not a snap-together, easy-to-build kit but a hobby kit, so it takes some model-building skills. Be patient! Make sure all electrical connections are clean and free of corrosion. Sand metal parts before tying, crimping, or attaching them. Allow four hours to build your first robot. Jonathan Mills swears he can build a robot in one hour, but it takes me about two (while watching sports on TV). This could be a wonderful parent-child project (in fact, my junior-high-school-aged daughter likes to "build bugs with dad"). Make sure to block out enough time to complete the kit.
The intent of this kit is to allow builders to create a platform from which they can start experimenting. The instructions provided in Chapter 2 show how you can create a Stiquito that walks with a tripod gait, that is, it allows three legs to move at one time via control from the printed circuit board. What you should do is to examine your goals for building the Stiquito robot and plans for controlling how Stiquito walks. If your plans include a two-degrees-of-freedom robot, then you should modify the assembly of your robot such that you attach two Flexinol(r) wires to each leg. If the design of your robot includes adding sensors to the printed circuit board on top, you should consider the function and weight of the added circuitry and programming of the robot.
This book can be used for an Introduction to Robotics class or it can be used as a supplement in many different types of classes. Previous Stiquito books have been used in high schools in an Introduction to Technology class, in community colleges as an Introduction to Robotics class, and in universities in many different classes: First Year Engineering, Introduction to Electrical Engineering, Introduction to Robotics, Introduction to Bioengineering, Robotics, and Senior Capstone projects. This book, Stiquito Controlled!, can be used for those courses as well as for an Introduction to Embedded Systems course. How you use this book is, of course, up to you, but there are several suggestions below of which chapters to use for those who may want to use this book in classes. Since this book comes complete with assembly instructions as well as a robot kit, it can easily serve as a required textbook for a class, and only needs a minimal amount of additional electronics necessary to investigate the other areas.
Chapter 1 provides an introduction to robotics and introduces Stiquito to those who may not be familiar with it. It could be used in all classes since it provides a good background to students.
Chapter 2 is an introduction to the discipline of embedded systems. It discusses microprocessors, microcontrollers, and complete computer systems. It then discusses the Stiquito controller board specifications and features. It could be used in all classes since it provides a broad assessment of technology central to the control of Stiquito and other robots.
Chapter 3 is an introduction to the design and manufacture of printed circuit boards. This will be of particular interest to Electrical Engineers and Roboticists, and could be included in courses in these disciplines. Chapter 4 shows how to build Stiquito for use with the microcontroller printed circuit board. It also has instructions on how to add other connectors so you can program the board. These new instructions no longer have the manual controller included in the assembly process. Again, it is a central part of the book and could be used in all classes. Chapter 5 describes the Stiquito printed circuit board in more detail. It provides hardware-interfacing instructions and programming steps for the Texas Instruments MSP430 microcontroller on the board. This chapter could be used in robotics and embedded- systems courses.
The Stiquito body is also designed such that all twelve large holes can be used for allowing the legs to have two degrees of freedom (just like Sticky and Stiquito II). Chapter 6 describes another type of microcontroller-based Stiquito that uses two degrees of freedom (lifting legs, as well as moving legs forward) to have Stiquito walk like a real insect. This chapter could be used in robotics and embedded-systems courses.
Chapter 7 describes how to experiment with different types of leg lengths and assembly designs, as well as gaits. This chapter could be used in robotics courses.
In Chapter 8 we describe some additional research areas and ideas that you can explore on your own. We provide several short examples of what others have done with Stiquito. This can be used in all courses.
As with any project conducted in a school setting, you may need additional supplies for those cases in which students break their robot kit. Contact the publisher, John Wiley & Sons, Inc., to purchase additional kits, or contact some of the suppliers listed in the back of the book for repair materials.
Some Final Comments
In your building activities, we cannot stress the importance of following common safety practices:
Wear goggles when working with the kit. Many parts of the kit act as sharp springs!
Use care when using a hobby knife. Always cut away from you.
Use care when using a soldering iron. Watch out for burns!
This kit is intended for adults and for children over the age of 14.
Excerpted from Stiquito Controlled by James M. Conrad Copyright © 2005 by IEEE Computer Society. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents1. An Introduction to Robotics and Stiquito.
2. Making a Stiquito Robot using Screws.
3. Making a Light-following Stiquito Robot.
4. Introduction to Microcontrollers and Embedded Systems.
5. Stiquito Controlled! Using the Stiquito Processor Board.
6. Making and Programming a Basic Stamp Circuit to Run your Stiquito Robot.
7. Further Experiments.
Appendix A: Biographies.
Appendix B: Suppliers.
Appendix C: Index.