Tạp chí Servo
Vol. 6 No. 12 SERVO MAGAZINEROBOT BUILDING BASICS•BLDC MOTOR•ARTIFICIAL MUSCLES•TANKBOT•GAIT DETECTIONDecember 2008 Let your geek shine. Meet Pete Lewis, lead vocalist for the band Storytyme. Pete recently created the RS1000, a new personal monitor system for performing musicians. It was SparkFun’s tutorials, products and PCB service that enabled him to take his idea to market in less than a year. The tools are out there. Find the resources you need to let your geek shine too. ©2008 SparkFun Electronics, Inc. All rights reserved. Hear music from Storytyme at www.storytymeband.com, or check out Pete’s RS1000 at www.rockonaudio.com. Sharing Ingenuity WWW.SPARKFUN.COM Full Page.qxd 7/9/2008 9:57 AM Page 2 TM l ogic Decide if Logic is worthy of your workbench at saleae.com. Introducing Logic, the new Logic Analyzer with SPI, Serial, and I2C. Now shipping for $149. Problem Seen. Problem Solved. Full Page.qxd 11/4/2008 9:54 AM Page 3 Features 20 BUILD REPORT: Cloud of Suspicion 22 MANUFACTURING: Laying Out Your Work Area 27 PARTS IS PARTS: 2.4 GHz Radio Fail-safes Events 24 Event Report: Robothon Robot Combat 2008 28 Results and Upcoming Competitions Robot Profile 26 Micro Drive SERVO Magazine (ISSN 1546-0592/CDN Pub Agree#40702530) is published monthly for $24.95 per year by T & L Publications, Inc., 430 Princeland Court, Corona, CA 92879. PERIODICALS POSTAGE PAID AT CORONA, CA AND AT ADDITION- AL ENTRY MAILING OFFICES. POSTMASTER: Send address changes to SERVO Magazine, P.O. Box 15277, North Hollywood, CA 91615 or Station A, P.O. Box 54,Windsor ON N9A 6J5; cpcreturns@servomagazine.com 06 Mind/Iron 12 Events Calendar 18 New Products 66 Robotics Showcase 68 SERVO Webstore 72 Menagerie 81 Robo-Links 81 Advertiser’s Index Columns 08 Robytes by Jeff Eckert Stimulating Robot Tidbits 10 GeerHead by David Geer Artificial Muscles 14 Ask Mr. Roboto by Dennis Clark Your Problems Solved Here 58 BasicBoard Robotics by William Smith BasicBoard Programming Options 62 Robotics Resources by Gordon McComb So You Want to Build a Robot 74 Appetizer by Shane Colton Build a Self-Balancing Scooter 77 Then and Now by Tom Carroll Japanese Robotics PAGE 20 4 SERVO 12.2008 THE COMBAT ZONE . Departments TOC Dec08.qxd 11/5/2008 9:18 PM Page 4 12.2008 VOL. 6 NO. 12 SERVO 12.2008 5 30 Learning To Drive: The BLDC Motor by Fred Eady Keep your robots runnin’ with this latest addition to the motor arsenal. 34 Getting Control With the Propeller: Part 4 by Chris Savage Propeller Multi-Controller. 38 Multi-Purpose, Daisy-Chained Gait Detection System by Balakumar Balasubramaniam and Wendi Dreesen This inexpensive system lets you monitor your (or your robot’s!) rhythm and stride pattern. 44 Ambient Intelligence by Fulvio Mastrogiovanni AmI is a multidisciplinary approach using intelligent systems around us to help in daily activities. Or, you could just call it a Smart Home, too. 48 Build The Ultimate Robot by Michael Simpson Part 3: Base Assembly. 54 Taking Control of Your SERVO TankBot by Ron Hackett This time, take a look at centering the TankBot’s servo motors and implementing a Universal TV remote for control. PAGE 48 PAGE 74 Features & Projects TOC Dec08.qxd 11/5/2008 9:19 PM Page 5 Published Monthly By T & L Publications, Inc. 430 Princeland Ct., Corona, CA 92879-1300 (951) 371-8497 FAX (951) 371-3052 Webstore Only 1-800-783-4624 www.servomagazine.com Subscriptions Toll Free 1-877-525-2539 Outside US 1-818-487-4545 P.O. Box 15277, N. Hollywood, CA 91615 PUBLISHER Larry Lemieux publisher@servomagazine.com ASSOCIATE PUBLISHER/ VP OF SALES/MARKETING Robin Lemieux display@servomagazine.com EDITOR Bryan Bergeron techedit-servo@yahoo.com TECHNICAL EDITOR Dan Danknick dan@teamdelta.com CONTRIBUTING EDITORS Jeff Eckert Tom Carroll Gordon McComb David Geer Dennis Clark R. Steven Rainwater Fred Eady Kevin Berry Michael Simpson Chris Savage Wendi Dreesen Fulvio Mastrogiovanni Shane Colton Thomas Kenny Blake Hooper Rob Farrow William Smith Ron Hackett Balakumar Balasubramaniam CIRCULATION DIRECTOR Tracy Kerley subscribe@servomagazine.com MARKETING COORDINATOR WEBSTORE Brian Kirkpatrick sales@servomagazine.com WEB CONTENT Michael Kaudze website@servomagazine.com PRODUCTION/GRAPHICS Shannon Lemieux AJ Cohen ADMINISTRATIVE ASSISTANT Debbie Stauffacher Copyright 2008 by T & L Publications, Inc. All Rights Reserved All advertising is subject to publisher’s approval. We are not responsible for mistakes, misprints, or typographical errors. SERVO Magazine assumes no responsibility for the availability or condition of advertised items or for the honesty of the advertiser. The publisher makes no claims for the legality of any item advertised in SERVO.This is the sole responsibility of the advertiser.Advertisers and their agencies agree to indemnify and protect the publisher from any and all claims, action, or expense arising from advertising placed in SERVO. Please send all editorial correspondence, UPS, overnight mail, and artwork to: 430 Princeland Court, Corona, CA 92879. Mass Customization I’m convinced that the future of robotics — especially service robotics — is tied to the development and acceptance of mass customization. Consider the typical challenges faced by an enthusiast in creating a complete robot. First, there’s the hardware platform — from the supporting infrastructure to the drive train to the effectors. Unless you start from scratch — a costly and time-consuming affair — you must identify and purchase a crawler or roamer or other platform suitable to your needs. However, have you ever tried mixing and matching an arm from one manufacturer with the body of another? Even if it’s possible to readily bolt the effector securely to the main body, there remain issues from electrical connectivity to how to best compensate for the extra weight and shift in the center of gravity. Then, there’s the issue of sensor selection — from US range detectors to IR radar. Again, this is a task- and cost-dependent selection, assuming what you need is even available off- the-shelf. There’s also the power system, communications system, and all-important computational hardware and software to consider. Typically, you must either cobble together a unique assemblage of components from a variety of vendors or buy a pre-configured robot from a single vendor that’s (at best) a compromise. On top of it all, because your final robot is a unique assemblage of components, sensors, effectors, and software, the software routines crafted by another developer will probably require significant modification before they’re useable in your robot. Other industries facing the same challenges turned to the mass customization model, often with astounding commercial success. For example, take Dell and Apple. When you order a PC from the Dell website, you scroll through pages describing options and prices. You add whatever features you can’t live without — while knowing that regardless of your choices, the machine will boot and run your favorite programs. The Apple website offers many of the same design options — including drives with various capacities, DVD and CD player/recorder options, extra memory, video memory, and monitor sizes. This is possible because each component manufacturer abides by industry standards. Mass customization has been applied successfully to other, less obvious industries, as well. For example, one of my interests is building, refurbishing, and playing electric guitars. However, as with robotics, designing a guitar involves careful consideration of myriad factors. Critical issues range from neck size and geometry and the number and configuration of electronic pickups, to the composition of the body. All of these factors and more affect the tone and play-ability of a guitar. Furthermore, to put the pieces together requires an expensive set of specialized tools and the expertise to use them. The mass customization companies catering to custom guitar builders (such as Mind / Iron by Bryan Bergeron, Editor Mind/Iron Continued 6 SERVO 12.2008 Mind-Iron Dec08.qxd 11/5/2008 4:33 PM Page 6 SERVO 12.2008 7 P erform proportional speed, direction, and steering with only two Radio/Control channels for vehicles using two separate brush-type electric motors mounted right and left with our mixing RDFR dual speed control. Used in many successful competitive robots. Single joystick operation: up goes straight ahead, down is reverse. Pure right or left twirls vehicle as motors turn opposite directions. In between stick positions completely proportional. Plugs in like a servo to your Futaba, JR, Hitec, or similar radio. Compatible with gyro steering stabilization. Various volt and amp sizes available. The RDFR47E 55V 75A per motor unit pictured above. www.vantec.com STEER WINNING ROBOTS WITHOUT SERVOS! Order at (888) 929-5055 www.FirstAct.com) take care of the standards issues, allowing you to focus on appearance and geometry. The universe of possible components isn’t available to you, but the component selection is generally rich enough to create a custom guitar suitable for any budget. As a result, with a click of the mouse and credit transaction a custom guitar can be at your doorstep in a matter of weeks. No need to fully equip a woodworking shop or learn how to wire your own pickup coils, and (given the skill) you can play music written for any other electric. So, if mass customization can work for other industries, why has it been slow to take off in robotics? One factor is the lack of a deep-pocketed Dell or Apple in the world of robotics. A few hardware platforms have been widely accepted by the enthusiast community — the Parallax BoeBot comes to mind. However, most robot models sell in the hundreds unless they make it to the game/entertainment market. The underlying issue is, of course, the lack of an industry standard robot configuration (akin to the PC) or a proprietary design with a devoted following (akin to the Apple Mac). Certainly, standards have been advanced to assist in the development of reusable robot software components (such as the Microsoft Robotics Studio) and several vendors offer platforms ready to be populated with components. But there are no real robotics standards from a body large enough to enjoin the entire consumer robotics industry, such as the IEEE. So, what can we do, as mere enthusiasts, to nudge mass customization of robotics along? Do what developers in other industries do: Identify best of breed and then integrate them into a good product line. The first hurdle is, of course, defining “best,” given each component manufacturer has a stake in declaring their product as such. Take a moment and imagine what you’d do, given unlimited access to commercial robotic components and systems. What’s the best platform out there for small service robots? Medium sized? What are the best (i.e., most affordable, easily programmed, compatible, etc.) controllers? Sensors? Motors? As a first step in developing industry recognized standards, a consortia of companies and developers could interface the best out there and then provide options to suit different classes of users. If you or your group/company is up for the challenge — or currently engaged in the challenge — then please drop me a line. It’s time to connect like-minded developers. SV Mind-Iron Dec08.qxd 11/5/2008 4:06 PM Page 7 8 SERVO 12.2008 Stereo Vision System Introduced If your bot or other homebuilt device needs 3D vision, check out the Surveyor SVT™ : a dual-camera, dual- processor Wi-Fi system geared for robotics, embedded image processing, and Web-based remote monitoring. Surveyor (www.surveyor.com) points to features including on-board programmability, Wi-Fi connectivity, easy sensor and actuator interface, open source architecture, and a list price of $550 as key attributes. You may note from the photo that the SVT employs Analog Devices’ Blackfin processors, which are designed for such things as multi- format audio, video, voice and image processing, etc. (details at www.ana log.com). According to Surveyor literature, the system takes “full advantage of the processor’s power efficiency, optimized video instruc- tions, high speed video interface, and easy interface to peripheral devices.” It incorporates two BF537 32-bit Blackfins, two Omnivision OV9655 1.3 megapixel cameras, PWM motor control, various interfaces, and 3.3V and 5V regulation for battery operation. You also get a Lantronix Matchport 802.11bg radio, all of which takes up only a 2.5 x 6 x 2 inch volume and consumes less than 2W. Programming can be via Windows, Mac OS X, or Linux. Bee Safer on the Road At the recent CEATEC Japan show, Nissan (www.nissan-global. com) unveiled its concept for automotive safety in the form of the Biomimetic Car Robot Drive, also known as BR23C. According to Nissan, it is based on lessons learned from the “humble bumblebee,” specifically the bee’s vision system. The insect’s compound eyes can spot obstacles in a 300°+ range, allowing it to fly safely within its personal space. In the automotive version, Nissan’s Laser Range Finder (LRF) system covers 180° and has a sensor range of 2 m toward the front. The LRF calculates the distance to another object and sends the data to an onboard micro- processor, which translates it into a collision avoidance strategy. But a bee can bumble up, down, or sideways to avoid other bees, whereas the BR23C can only move in two dimensions and only within the limitations of the wheels. Presumably, the operating range of 2 m is a prototype limitation, as it would appear advisable to detect a pending collision with a bit more time to react. Let’s say you’re driving toward a tele- phone pole or other stationary object at 60 mph (88 ft/sec) and detect an obsta- cle at a distance of 10 ft. That would allow only about 1/10 sec reaction time — enough time for an airbag to deploy, but not so hot for braking or swerving. Nissan says the device “only needs to process inputs every few seconds, and act on that.” Hmmm. In any event, the company hopes that the system will cut the number of accident fatalities and serious injuries to Nissan drivers by half by 2015, as compared with 1995. And Bee Careful of Flying Objects Another ostensible offspring of the genus Bombus is the KillerBee unmanned aircraft system, which is being provided to the US Navy and Marine Corps by a team made up of Swift Engineering and Raytheon (details at www.killerbeeuas.com). It looks more like a manta ray leaping through the surface of the gulf, but it’s considerably more lethal than either one when connected to com- bat and command control systems. According to a recent announcement, “KillerBee has the ability to insert persistent intelligence, surveillance, and reconnaissance (ISR) into the bat- tle space and rapidly deliver actionable intelligence to combatant commanders.” Late in September, a Raytheon flight operations crew simulated a combat environment by delivering the KillerBee system to a remote location via Humvees. In less than 45 minutes, the crew set up by Jeff Eckert Robytes The SVT™ dual-camera, dual-processor stereo vision system. Courtesy of Surveyor Corp. Nissan’s BR23C uses compound “eyes” for collision avoidance. Courtesy of Nissan Motor Company Advanced Technology Center. The KillerBee — a fully autonomous UAS — will be used by the US Navy and Marine Corps for both ground-based and ship-launched surveillance and reconnaissance. Courtesy of Raytheon Corp. Robytes Dec.qxd 11/5/2008 6:46 PM Page 8 the system and launched the UAS. The team then executed the opera- tional scenario (details not revealed) and safely retrieved the UAS. Specs are sketchy, but we did find out that KillerBee is fully autonomous, with no piloting skills needed by the operator. Maximum takeoff gross weight is 164 lb, and it’s powered by an 8 hp engine fitted with a two- blade prop. The stall speed is 45 kt, and loiter speed is 55 kt. Mission endurance is 15 hr, and it has an impressive range of 972 nautical miles. AUV Hovers Underwater Researchers at MIT (www.mit. edu) have revealed the new Odyssey IV — a small, inexpensive robo sub that can hover like a helicopter, which should be really handy for deep-water oil explorers, marine archaeologists, oceanographers, and other folks who need to loiter undersea for long periods of time. Whereas previous Odyssey models could operate only while moving forward continuously, the IV can stop anywhere in a water column and constantly correct for currents and obstacles. This makes it useful for things like making detailed inspections of an offshore oil plat- form and photographing flora and fauna around an undersea vent. In a sea trial completed off Woods Hole, MA, it performed at depths of up to 6,000 m. It can also be fitted with a mechanical arm, allowing it to grab samples and perform manipulations such as twisting a valve or clonking a lobster on the head. Odyssey IV is pretty swift, too, with a top speed of 2 m/sec. The ultimate goal is to develop a version that can stay underwater for up to a year, collect and transmit data, and ultimately return to its home base without the need to surface at all. RoboVox: All Talk For journalistic purposes, it is occa- sionally necessary to be flexible with the definition of a robot, and in the case of RoboVox we sag from flexible to flaccid. A creation of artist Martin Bricelj, the 8 m colossus doesn’t move or do anything robotic, but at least it looks like an automaton. Lest you leap to the conclu- sion that this is merely a pitiful cry for notoriety from a starving artist, note that it is presented as a socially relevant vehicle for freedom and self-expression. According to the creator, “Its purpose is to serve as a tool for an individual whose voice usually gets lost in the sounds of the mass, the society. An individual can send a text message using his mobile phone to the dedicated RoboVox’s number. Upon receiving the SMS, RoboVox says out loud the statement, the protest, the declaration of love, or whatever the message may read, thus lending its voice to the anonymous individual.” If you’re impressed, you can purchase RoboVox merchandise such as airline bags, T-shirts, and talk- ing soft toys. Just log onto www. robovox.co.uk and take your pick. It may be the perfect Christmas gift for that relative who has everything. SV Robytes SERVO 12.2008 9 Schematic shows Odyssey IV — a small, inexpensive robotic submarine that can hover in place. Courtesy of MIT Sea Grant AUV Lab. RoboVox appears in downtown Maribor, Slovenia. Robytes Dec.qxd 11/5/2008 6:47 PM Page 9 10 SERVO 12.2008 T he basic EPAM is a rubber sheet made of a custom-formulated elastomer, explains Ilya Polyakov, a senior mechanical engineer at Artificial Muscle, Inc., creators of the EPAM. The polymer is applied so that electrodes plate the rubber sheeting on both top and bottom. As voltage is applied positively and negatively through these electrodes, the dielectric rubber — which doesn’t permit the flow of electricity — produces an electrostatic force. This force pulls the electrodes together, pushing the EPAM out side-to-side at tenss of pounds-per- square-inch. This actuation is then harnessed for practical uses, including robot muscles. “Because our muscle membrane squeezes out proportionally to the electrical field applied, we can simply control the amount of movement,” says Polyakov. Harnessing EPAM Properties One of the most common building blocks using the EPAM is the universal muscle actuator (UMA) configuration, which is a jumping-off point for more complex applications. This configuration attaches two EPAM sheets/films at their centers, with a lightweight spacer between them. “Each stack of film is attached to a frameso it can be mounted. Each stack is also attached to an output disk which transmits the force and stroke of the expanding film to some load in order to perform work,” explains Polyakov. One practical use for EPAMs and UMAs is in valves. Existing valve systems convert high speed rotary motors running at thousands of RPMs to low speed linear motion for valve parts that move a few feet per second. The EPAM actuator eliminates the mechanical steps necessary for the speed conversion by offering low speed linear motion in the initial instance. This technology is called a roll configuration actuator, which employs a large stretch of artificial muscle film/membrane wrapped around a compressed spring. The spring pushes the cylinder of wound film into tension, Polyakov explains. “Once in tension, the application of the electric field to the film causes it to relax and produce a force imbalance between the spring and the connected films, Contact the author at geercom@alltel.net by David Geer Artificial Muscle (EPAMs) Today, Robotic Applications to Follow Electroactive Polymer Artificial Muscles (EPAMs) are a new actuating/motion technology based on polymers that react to electricity. The new actuators are useful across applications where motors are not as efficient or are simply not feasible. The valve on the left is an OTS proportional solenoid valve. The one on the right is EPAM powered with identical flow specs, and a directly attached power supply board. It weighs 1/7th the original unit and operates at 1/10th the power. This larger solenoid coil at left is used in commercial pneumatic valves. The coil at right — a 9.5 mm actuator stack based on EPAM technology — is capable of the same workload at a fraction of the commercial solenoid’s mass and volume. The commercial part weighs 70 grams compared to the EPAM’s 8. This small piece of hardware uses EPAM technology to auto focus optical lenses in mobile/cell phone cameras, according to Polyakov. A 9.5 mm EPAM actuator positions the lens based on data from a CMOS sensor. The hardware is encircled by a flex circuit power supply at 1.3 kV. The unit is specifieded to fit the standard SMIA 9.5 mm phone camera form factor. Geerhead Dec-edited.qxd 11/4/2008 4:12 PM Page 10