Servo magazine 02 2008

Tạp chí Servo

Vol. 6 No. 2 S E R V O MAGAZINEROBOTS AT MAKER FAIRE • PERSONAL ROBOTS • MECHBASH • BATTERY CAPACITYFebruary 2008 Cover.qxd 1/10/2008 1:04 PM Page 1 Full Page.qxd 1/7/2008 1:46 PM Page 2 Full Page.qxd 1/7/2008 1:48 PM Page 3 4 SERVO 02.2008 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; cpcreturns@servomagazine.com Departments 06 Mind/Iron 20 New Products 30 Events Calendar 53 Robotics Showcase 56 Robo-Links 73 SERVO Webstore 82 Advertiser’s Index Columns 08 Robytes by Jeff Eckert Stimulating Robot Tidbits 10 GeerHead by David Geer Robot Leaves Breadcrumbs 14 Ask Mr. Roboto by Pete Miles Your Problems Solved Here 62 Robotics Resources by Gordon McComb The Recycled Robot 67 Lessons From The Lab by James Isom NXT Packbot: Part 3 76 Appetizer by Kevin Berry The Door Into Spring 78 Then and Now by Tom Carroll Personal Robots: From Science Fiction To Reality PAGE 48 PAGE 10 TOC Feb08.qxd 1/10/2008 10:51 AM Page 4 02.2008 VOL. 6 NO. 2 SERVO 02.2008 5 ENTER WITH CAUTION! 22 The Combat Zone 31 The RoboCooler by Jerry Reed Find a few design tidbits in this embedded “appliance” application to use in your next build. 39 The MechBash Traveling Robot Show by Jon Vandervelde See what happens when you combine Mechwars robot combat with BotBash into one event. 43 Maker Faire by R. Steven Rainwater Pleos, horses, monkeys, and parrots were just a few of the robotic pets that Faire attendees had the opportunity to get up close and personal with. 48 Building a Stepper Motor Controller: Part 1 by Fred Eady This controller is based on the STMicroelectronics L6208, which is a single-IC DMOS driver. 54 Capacity: The Key to Battery Runtime by Isidor Buchmann Take a quick look at emerging rapid-test technologies for deep-cycle, lead-acid batteries. 57 Reviving an Androbot BOB by Robert Doerr Get your BOB rolling again. Features & Projects PAGE 43 TOC Feb08.qxd 1/10/2008 10:53 AM Page 5 Published Monthly By T & L Publications, Inc. 430 Princeland Court 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 North 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 CONTRIBUTING EDITORS Jeff Eckert Tom Carroll Gordon McComb David Geer Pete Miles R. Steven Rainwater Fred Eady Kevin Berry James Isom Robert Doerr Isidor Buchmann Jon Vandervelde Jerry Reed Russ Barrow Chris Olin 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 Joe Keungmanivong 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. REFLEX CONTROL Although fully autonomous robots are often viewed as the pinnacle of robotics, sometimes it’s desirable for robots to follow specific directions, under direct user control. For example, a surgeon controlling a surgical robot may want to exactly specify the location of an incision. The cost of full user control is the demand placed on the operator. As experienced with the MQ-1 Predator and other drone combat aircraft has shown, the control of a single robot can require the full attention of several humans – the basic crew for a Predator is one pilot and two sensor operators. Similarly, if you’ve ever controlled a mobile or air-borne robot with an R/C unit through a video link — or even an R/C battle-bot in direct sight — you know that the task requires focus and concentration, leaving little room for other activities. Controlling robots — wearable or otherwise — through neuromuscular signals is an obvious, albeit challenging, approach to freeing the operator to focus on other tasks. Instead of handling a joystick, the operator simply moves an arm or leg and the exoskeleton follows, using the electrical signals activating the muscles as a trigger. (Watch for Kazuo Kiguchi’s article on “Control of ExoSuits with Biological Signals” coming in the March issue.) One of the issues in biological control of robots is how to handle reflexes — semi-autonomous movements that are not consciously directed. To understand the relevance of reflexes to robotics, consider your normal reflexes. If you accidentally brush your hand against the hot tip of a soldering iron, your hand will instinctively and — without conscious control — instantly recoil from the heat source. If you are fast enough, you might get away with a minor reddening of the skin that quickly dissipates. Without the reflex, you’d be left with a serious burn, possible infection, and a permanent scar. The reflex arc illustrated in Figure 1 involves sensors in your skin and muscle, a neurological pathway from the sensors to your spinal cord, a connection within the cord to the outbound motor neurons controlling muscles in your hand and arm, and neuromuscular innervation. The brain isn’t normally part of a reflex. When it is involved, it’s usually to inhibit the reflex — you don’t want to rip your arm away from a nurse giving you a vaccination, for example. A practical advantage of a reflex action is speed. Conscious control involving hundreds or thousands of neural synapses is simply slower than a reflex arc involving a few neurons. If you had to consciously blink every time something headed for you eyes, you’d probably be blind by now. Another advantage of reflexes is that they enable you to avoid danger or at least minimize damage while maintaining conscious focus on the task at hand. Given the advantage of near instantaneous reflexes in biological systems, it’s reasonable to assume that exoskeletons and other forms of robots can benefit from similar capabilities. However, a dilemma faced by developers of wearable robotic systems is the degree to which the wearer should be insulated from the environment. At one extreme, the wearer is unaware of extreme heat, impact, and Mind / Iron by Bryan Bergeron, Editor  Mind/Iron Continued 6 SERVO 02.2008 Mind-Feed Feb08.qxd 1/10/2008 11:09 AM Page 6 other dangers in the environment. It’s up to exoskeletons and built-in protective reflexes to keep the wearer from danger. The downside to this scenario is that the wearer would have to adapt to sudden reflex movements of the exoskeleton, and the movements would have to be controlled to avoid joint or muscle damage. At the other extreme, the wearer of a robotic exoskeleton would be exposed to whatever forces contact the exoskeleton, with fidelity determined by the available sensors and transducers. Somewhere in the middle seems reasonable for many applications. For example, a soldier with a bulletproof robotic exoskeleton should be protected from the physical damage of bullets or shrapnel, but not necessarily from a modest sting of impact. The modest pain would result in biological reflexes, and the exoskeleton could respond to the associated neuromuscular activity. Pain is often a reliable indicator that something is wrong and that action is necessary to avoid injury. The impact of shrapnel or a bullet on a soldier’s bulletproof exoskeleton could be translated into a mildly uncomfortable sensation on the wearer’s skin just beneath the point of impact. Along this line of reasoning, variants of Immersion’s TouchSense technology (www.immersion. com/industrial/touchscreen/) could be used to synthesize sensations through tactile transducers excited by signals of varying frequency, intensity, duration, and wave shapes. Tactile synthesis for wearers of sensor-studded exoskeletons, socks, or shoes has potential medical value, as well. Wearable sensors coupled with tactile synthesizers can replace and supplant the desensitized peripheral sensory organs of diabetics and other sufferers of peripheral neuropathy. It’s not unusual for sufferers of diabetes to tear a toenail or cut their foot, only to discover the damage hours later, when they happen to notice a blood-soaked sock. A thin, lightweight, flexible sensory exoskeleton that generates synthetic tactile feedback on the wearer’s back or other area not affected by neuropathy could provide life-saving feedback to diabetics, as well as advance the field of robotics. If you want to take up the challenge, start by exploring the computer literature on virtual reality and the psychological literature on perception and the synthesis of sensation. SV SERVO 02.2008 7 Spinal Cord Sensory Motor Muscle Heat FIGURE 1. Reflex Arc. 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 Mind-Feed Feb08.qxd 1/10/2008 11:06 AM Page 7 8 SERVO 02.2008 UAV Imitates Sea Birds So one day Guy Meadows, director of the Marine Hydrodynamics Labs at the University of Michigan (www. umich.edu), was floating around and saw a flying fish pop out of the water and soar over the waves. He was so impressed and inspired that he said, “Wow. I’ll bet I can build one of those,” hence the name of the UAV that he and some engineering researchers designed and built. Somehow the concept evolved away from fish and focused on sea birds, but the name stuck. In any event, Meadows and his colleagues did a study of things that go flap and discovered that many of them have some traits in common, such as weighing about 20 lb and having a 2 m wingspan. It turns out that this is pretty much the ideal aerodynamic design for skimming close to the surface, so the Flying Fish is physically similar to a large, mechan- ical pelican. It is also believed to be the first seaplane that can initiate and perform its own takeoffs and landings. It may sound like all fun and games, and a good excuse to escape Ann Arbor for some quality time in Monterey, CA, testing the thing, but project funding came from the DoD’s Defense Advanced Research Projects Agency (DARPA), with the aim of advancing the agency’s Persistent Ocean Surveillance program. In operation, the electric-powered UAV drifts along until its onboard GPS tells it that it has floated too far. The takeoff sequence is then triggered, and Flying Fish goes airborne in about 10 m. When it reaches the proper GPS coordi- nates, it lands using a shallow descent. The next step will be to fit the plane with solar power and an array of sensors. Bots to Fight Fires in London Apparently, there are a serious number of incidents in the London area involving fire, acetylene cylinders, and railroad tracks. Such incidents cause great consternation among rail travelers, as the lines have to be shut down until the danger has been eliminated. As a result, Network Rail, in conjunction with the London Fire Brigade, has commissioned QinetiQ Ltd. t o provide and operate some specialized firefighting ROVs for a six-month trial. The plan is to use the bots’ cameras to identify whether any acetylene cylinders are present when fire breaks out near the tracks and — using thermal imaging — gauge whether such cylinders have cooled off enough to allow human firefighters to approach them. Three types of ROVs are included in the trial: Talon, a small tracked vehicle used in Iraq for bomb disposal and here fitted with video and thermal image cameras; Black Max, basically a squirtbot; and Brokk 90, a heavy- duty mini-digger designed to remove debris and gain access to burning vehicles and structures. According to a company spokesman, “QinetiQ has already been called to deploy the ROVs on a number of occasions, and they have each proved useful in assisting the Fire Brigade in dealing with the incidents.” Sounds like a bit of all right. BigDog on the Block Also sponsored by the folks at DARPA is BigDog, billed as the most advanced quadruped robot on Earth. Built by Boston Dynamics, it is a major part of the agency’s Biodynotics (biologically inspired dynamic robots) program, which aims to apply biological principles to devel- op robots that can better move through difficult terrain, travel more efficiently, and recover from stumbles. The BigDog portion of the program aims to replace tracked and wheeled systems with legged ones, eventually demonstrating mule-sized, 200-lb platforms that can carry payloads of supplies, ammunition, weapons, and other items that soldiers now have to tote. At present, BigDog measures 1 m (3.3 feet) long, is 0.7 m (2.3 feet) tall, and weighs 75 kg (165 lb). The dog food this guy consumes is gasoline, which feeds an engine that drives the hydraulic actuation system. An on- The Flying Fish UAV. Photo courtesy of the University of Michigan. ROVs fire robots in action. Photo courtesy of QinetiQ Ltd. The BigDog quadruped robot. Photo courtesy of the US Department of Defense. by Jeff Eckert Robytes Robytes.qxd 1/10/2008 10:34 AM Page 8 board computer controls locomotion, the legs, and a complex variety of sensors. So far, BigDog has trotted 5.3 km/hr (3.3 mph), climbed a 35° slope, and carried a 54-kg (120-lb) load. For a fascinating video, visit www.boston dynamics.com/content/sec.php? section=BigDog. Raven Takes Flight It might look like a model airplane that you would fly in the park on Sunday, but the RQ-11B Raven is a serious little cousin of the MQ-1 Predator and MQ-9 Reaper. The little UAV weighs only about 4 lb and has just a 55-in (1.4-m) wingspan, but it can conduct visual reconnaissance up to 10 miles from its launch point and climb to 10,000 feet above sea level. It sends live footage back to the operator for later evaluation. According to a spokesman, the Raven B is particularly useful during convoy operations, because it can travel at 17 to 44 knots and keep up with most trucks. It is also good for target acquisitioning, battle damage assessment, and detection assess- ment for ground-based threats. Raven carries a camera that provides high-res imagery up to 500 feet above the terrain, with location coordinates shown on the display. It can remain air- borne for 1.5 hours on a charge. Perhaps its most interesting characteristic is that it has no landing gear; it is designed to break apart, undamaged, on impact, and it can be reassembled in a matter of minutes. The exact cost of the little bird was not disclosed, but the Danish Army recently ordered 12 systems (including logistics support and training) at a cost of $2.4 million, which would price it at $200,000. Yes, nothing you’ll be flying in the park for fun. SV Robytes Staff Sgt. Marie Garcia launches an RQ-11B Raven at Bagram Air Base, Afghanistan. US Air Force photo by Staff Sgt. Mike Andriacco. SERVO 02.2008 9 Robytes.qxd 1/10/2008 1:13 PM Page 9 10 SERVO 02.2008 M oravian College student and roboticist Wesley Moser (class of ‘08) built a robot that could trace its steps and map them out on a computer screen, albeit with a lot of help from Moser’s own software, which he programmed using multiple languages. The robot was the result of Moser’s Student Opportunity for Academic Research (SOAR) project at Moravian. Ben Coleman, assistant professor of computer science at the academic institution, guided Moser. The robot uses a variety of sensors to traverse the boundaries of its given landscape; in this case, a box. Along with the ability to avoid obstacles — without which it would be quite clumsy — its sensors and computer technology enable it to record where it has been. The robot then distributes the information to a computer, which draws a line duplicating the robot’s path. Mapping and Maneuvering the Robot’s Intelligence Technically, the robot itself doesn’t actually know where it has been, according to Moser. As the robot rolls around inside its little playpen, it keeps a heading. Every few parts of a second, it sends its heading back to a computer (laptop). The heading is simply information about whether it is turning or not and in which direction, according to Moser. Along with the heading, the robot returns its recent sensor readings and gives the computer the exact time since its last update, Moser explains. The computer then compiles all of these readings in real-time and generates a single-line mapping of where the robot has been. “In this case, the robot is really the ‘explorer’ and the laptop has to do all the work of knowing where the robot was,” continues Moser. The robot houses its intelligence in a Handy Board. The Handy Board consists of a Motorola MC68HC11 processor, 32K of RAM, and a variety of sen- sor inputs. It also supports four motors. Despite its comparably slow clock speed, the 2 MHz processor was just speedy enough to shoulder all the responsibilities Moser had developed for it. “We were coming up on its limit when trying to send data to the computer, collect data readings, and determine the next heading all at once,” Moser notes. Moser used a programming language called Interactive-C to enable the robot’s ‘cranium’ so it could ‘think.’ Through this programming, the robot could complete tasks like polling sensors for data, controlling its motors, and doing direct access calls to the on-board RAM. Moser first programmed the robot with a path-finding ability, with both the robot and sonar facing straight ahead. But he quickly discovered that the robot collided with walls when approaching them from an angle. Moser needed the robot to be able to see obstacles from all sides, and so he added a servo to turn the sonar side to side. Still, the robot crashed into walls, so Moser added infrared sensors so the robot could sense when it was too close to the walls of its box, whether the sonar agreed or not! Once Moser had decided to save the robot’s path and record it, he real- ized he had to do more programming. “I added some programming routines to get the robot to remember what it had done, but the robot only had enough memory to remember the previous 30 seconds,” Moser says. Moser had to clear that memory and move that data off the robot to another computer to make room for each new wave of information. While Moser considered a wireless link to Contact the author at geercom@alltel.net by David Geer Robot Leaves Breadcrumbs A trailblazer that traces its own steps This is a front and side angle view of the fully assembled robot. Geerhead.qxd 1/10/2008 10:25 AM Page 10