09 4 $7.00 CANADA $5.50 71486 02422 $5.50US $7.00CAN 0 U.S. CoverNews_Layout 1 8/8/2012 10:02 AM Page 1 Vol. 10 No. 9 SERVO MAGAZINE TIGERBOT • ROS ON A CHIP • PARALLAX QUADCOPTER • MATE ROV 2012 September 2012 Full Page_Full Page.qxd 8/7/2012 11:57 AM Page 2 TOC SV Sep12.qxd 8/7/2012 9:51 PM Page 4 09.2012 VOL. 10 NO. 9 PAGE 68 Columns 08 Robytes by Jeff Eckert Stimulating Robot Tidbits 10 GeerHead by David Geer RIT TigerBot: A Platform for Important Medical Research 14 Ask Mr. Roboto by Dennis Clark Your Problems Solved Here 68 Twin Tweaks by Bryce and Evan Woolley The Cobra Strikes Again 74 Then and Now by Tom Carroll Sensors for Mobile Robots — PAGE 08 Part 4 Departments 06 Mind/Iron PAGE 22 07 Bio-Feedback 19 Events Calendar PAGE 74 20 New Products 21 Showcase 22 Bots in Brief The Combat Zone... 64 SERVO 30 Webstore BUILD REPORT: Siafu: An Army of Ants — Part 4 80 Robo-Links 80 Advertiser’s 33 Upcoming Events Index 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 ADDITIONAL 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; [email protected] 4 SERVO 09.2012 TOC SV Sep12.qxd 8/7/2012 9:52 PM Page 5 In This Issue ... PAGE 36 36 MATE ROV 2012 60 A Robot Operating System International Competition On a Chip by Morgan Berry by John Blankenship and Samuel Mishal Wrap-up of this year’s event held in Orlando, FL. Building a robot from scratch can be a daunting task for both beginning and advanced Far Eastern Federal hobbyists. The newly available RobotBASIC 40 ROS on a Chip makes the whole process easier University’s ALIEN ROV and faster by providing a physical interface from Revealed! simulations to the real deal. by Kevin Berry Learn more about “Primorye Coast’s” first place entry in this year’s MATE ROV event. 44 Parallax Elev-8 Quadcopter PAGE 44 — Part 1: Mechanical Build by Bryan Bergeron Ready to take your robotics experiments to new heights? Then follow along with this helpful kit build that will have you up and flying in no time. 54 Electronic Messaging With Your Robot by Fred Eady Water and things electrical normally don't mix. That's probably why you never see a robot lick a stamp. Electronic messaging is the safer solution for a robot that wants to put a note in your mailbox. This time around, we'll explore what it takes to have your mechanical animal put an electronic note in your inbox. SERVO 09.2012 5 Mind-Iron - Sep 12.qxd 8/7/2012 3:07 PM Page 6 FOR THE ROBOT ERVO Mind / Iron INNOVATOR Published Monthly By by Bryan Bergeron, Editor T & L Publications, Inc. 430 Princeland Ct., Corona, CA 92879-1300 (951) 371-8497 Danger, Will Robinson! FAX (951) 371-3052 Webstore Only 1-800-783-4624 Robots are supposed to be great for the dirty, dull, and dangerous. Then www.servomagazine.com on the flip side, for companionship and help around the house. However, it’s Subscriptions easy to forget that robots can be perceived as — and sometimes are Toll Free 1-877-525-2539 themselves — dangerous. It’s something to consider when you work with Outside US 1-818-487-4545 robots around non-enthusiasts and when you’re designing your next platform. P.O. Box 15277, N. Hollywood, CA 91615 If you ever visit an automated factory with a robotic welding shop, you’ll PUBLISHER see that many of the machines are either fenced off or have a safety zone Larry Lemieux painted on the floor. Enter the zone or jump the fence and you’ll risk serious [email protected] injury. Most people expect a factory full of powerful, robotic arc welders and ASSOCIATE PUBLISHER/ assemblers to be a dangerous place. The greatest practical danger to a VP OF SALES/MARKETING traditional factory worker is often job security. Robin Lemieux From a safety perspective, Google’s driverless car — undoubtedly the [email protected] future of driving — isn’t there yet. The modified Toyota Prius is essentially in EDITOR permanent driver’s ed class, with a human emergency operator/observer in the Bryan Bergeron [email protected] car whenever the motor is running. Although legal in Nevada, like I said, the car isn’t quite there yet. Until it can automatically, say, come to a stop when a CONTRIBUTING EDITORS Jeff Eckert Jenn Eckert five year old girl on a tricycle bounds out into the street, the car will be Tom Carroll David Geer considered too dangerous for consumers. I suspect that the US DOD has Dennis Clark R. Steven Rainwater several driverless transport vehicles on order, however. Kevin Berry Pete Smith If you’ve kept up with the work of the amazing folks at Willow Garage Morgan Berry Fred Eady John Blankenship Samuel Mishal (www.willowgarage.com) — home Bryce Woolley Evan Woolley of the Robot Operating System — you know that PR2 is probably the CIRCULATION DEPARTMENT leading edge in personal robot [email protected] appliances. It’s an impressive MARKETING COORDINATOR robotics platform for serious WEBSTORE academic R&D. I’d love for a chance Brian Kirkpatrick [email protected] to have access to one of these $400K machines. However, it’s not WEB CONTENT Michael Kaudze something that I’d want roaming [email protected] around my kitchen wielding a cleaver or helping me put on my tie ADMINISTRATIVE ASSISTANT Debbie Stauffacher in the morning. Those pincer hands just look too cold and powerful to PRODUCTION/GRAPHICS Shannon Christensen me, and they must seem doubly so Sean Lemieux to someone not familiar with Copyright 2012 by robotics. T & L Publications, Inc. Then, there’s my latest All Rights Reserved experimental robotics platform of All advertising is subject to publisher’s approval. choice: the quadcopter. While small We are not responsible for mistakes, misprints, units can be flown indoors, they’re or typographical errors. SERVO Magazine assumes at their best outdoors where larger no responsibility for the availability or condition of craft sporting GPS and Google Maps advertised items or for the honesty of the advertiser. The publisher makes no claims for the and a variety of other sensors can legality of any item advertised in SERVO.This is the be used to determine waypoints and sole responsibility of the advertiser.Advertisers and photograph points of interest. their agencies agree to indemnify and protect the Working with the larger, outdoor publisher from any and all claims, action, or expense arising from advertising placed in SERVO. Please quadcopters is also a great excuse send all editorial correspondence, UPS, overnight to get outside, away from the mail, and artwork to: 430 Princeland Court, workbench. However, many city Corona, CA 92879. governments (and police) see Printed in the USA on SFI & FSC stock. 6 SERVO 09.2012 Mind-Iron - Sep 12.qxd 8/7/2012 3:08 PM Page 7 Dear SERVO: I just wanted to point out to you in the Sept ’11 Mr. Roboto column that torque and force are not equivalent. Forces have units of Newtons and torque has units of Newton*meters. Motors should be rated in N*m (Force*Length) or N*mm of torque, but many of them are given in kg*cm or g*cm, etc. Note that this is the manufacturer's ignorance of the difference between mass and force, and they are rating their motors for the forces those masses produce as weight under Earth's standard surface gravity. Also, sizing a motor to turn a wheel has nothing to do with sliding friction. The coefficient of rolling friction between a rubber wheel and concrete is more accurately on the order of 0.01. It may increase closer to 0.10 for older cars with multiple bearings and rough contact, etc. If it was closer to 1.0, it would require 2,700 lbs of lateral force to make a car budge, but I would estimate that it only takes about 50 lbs of lateral force, suggesting a coefficient of (rolling) friction around 0.02. Keep in mind that the formula P(max)=(1/4)*T(max)*ω(max) is an idealized approximation. In reality, each motor has a highly nonlinear torque-speed curve that looks more like a rounded hill than a flat linear (ideal) decline from max torque at zero rotational speed to zero torque at max rotational speed. The final thing I'll mention is to remind people to use good engineering practice and build in a factor of safety, since all of our measurements for the components of these equations are estimates. I've found 1.5 works well for most robotics applications if the parameters are known well; 2.0 if estimates are fairly rough or if the application of the robot is still largely undetermined. I do enjoy this magazine. Jesse Maxwell Mechanical Engineer Metal Storm, Inc. quadcopters and variants as large R/C aircraft that are already banned from flying down busy city streets. Even if your local community doesn’t have laws about R/C model aircraft, as the operator you need to consider the personal liability involved if a two pound Lithium-Ion battery ends up smashing a car’s windshield and then exploding.