Month: January 2007

In the current issue of MAKE (Vol. 8), I have a piece on Pummers, a type of solar-powered robotic plant life. I’ve known about Pummers for years, but my inspiration for doing the MAKE piece was finding Zach Debord’s gorgeous Pummer set on Flickr. Being an artist and designer, Zach understands the value of making miniature robots that are as beautiful as they are functional. Mark Tilden, the “Big God” of BEAM robotics, has a wonderful adage that a human is a way that a robot makes another robot. One “evolutionary strategy” here is centered on aesthetics. Aesthetics drive interest. The Pummer piece is a prime example. I saw Zach’s bots, I was wowed by their beautiful designs, and wanted others to see them. The piece got published, and now, if you search on Pummer in the MAKE Flickr pool, you see other people are making them. The robots are replicating themselves.

In the realm of behavior-based robotics, BEAM, bio-mimics, and other bottom-up, bug-brained approaches to robotic design, nearly every conceivable form of motility has been tried. There are bots on wheels, two-, four-, six-, eight-legged bots, bots with whegs (wheel/leg crossbreeds), snakebots, spinnerbots, swimmers, fliers, climbers. You name it. One of the less documented types of robotic motility is found in the Vibrobot, a type of robot that gets around by shimmying, shaking, and scooting. It’s not the most graceful or accurate way to explore the world, but it’s very easy to build a Vibrobot and they’re really fun (and funny) to watch.

The key to Vibrobot movement is a motor (or motors) that employs an unbalanced weight. Pager and other motors used to create vibration alerts in consumer electronics use this technique. As the motor shaft spins, the weight on the shaft, being off-kilter, makes the motor, and therefore the entire pager, vibrate. Hook such a motor up to a little robo-critter with four fixed legs, and when the motor fires and the weight starts spinning, the bot will skitter across the floor. That’s all there is to it. Since the legs don’t need to be articulated or driven, there are few mechanical challenges in building a Vibrobot. The power circuit is very simple too. The simplicity of the mechanics and electronics frees you up to put more effort into making the bots look incredibly cool. It’s no wonder then that, as with Pummers, Zach has built an amazing menagerie of Vibrobots. We asked him to tells us how he goes about building these wacky little robo-critters.

Here’s a call-out image that details the parts used in a basic Vibrobot (the Solar Engine circuit is detailed in the diagram below).

As you can see, it’s all fairly simple. This Vibrobot uses the FLED (as in “Flashing LED”) version of a Type 1 Voltage-Triggered Solar Engine. This type of common BEAM power circuit was discussed in my “Beginner’s Guide to BEAM” and the “Two BEAMBots” projects in MAKE Vol. 6. This is the same FLED Type 1 SE used in Zach’s Twin-Engine Solarroller we wrote about on Street Tech a few months back. In that piece, tI quote from a reasonably clear explanation of how a FLED-driven voltage trigger works from well-known BEAM builder Wilf Rigter.

Here is a schematic for the basic FLED SE circuit, taken from Beam-Online.

Parts List

Here’s the list of parts that Zach uses to build a basic single-motor Vibrobot. Solarbotics parts numbers are given, but you can also get many of these parts from your own techno-junk collection, from Radio Shack, or other electronics sources (see “Resources List” below).

Quant	Part	Solarbotics Parts #	Notes
1	Pager Motor	#RPM2	With weight still attached
1	3v Solar Cell	#SC2433	Any 3v cells, such as the 24mm x 33mm ones SB sells
1	4700uF cap	#CP4700uF	N/A
1	2N3904 NPN transistors	#TR3904	N/A
1	2N3906 PNP transistors	#TR3906	N/A
1	Flashing LEDs	#FLED	N/A
1	2.2K-ohm resistors	#R2.2k	N/A
N/A	Heat Shrink Tubing	N/A	Radio Shack has an assortment in various sizes. You’ll want tubing all the way up to 2″ dia.
1	Medium-Size Paper Clip	N/A	N/A
N/A	Guitar String	N/A	N/A
N/A	Red and Black Hook-Up Wire	N/A	Used to attach solar cell to SE circuit

This bot has two pager motors. The first one (on top) has a fan attached to it. This doesn't have much purpose besides offering some kinetic visual interest.

Zach’s Building Tips

Zach offers the following bits of additional bot-builder wisdom for success in creating your own Vibrobots:

• The key to a good Vibrobot is to keep it as lightweight as possible so the motor can really jiggle it around when it fires.
• Play around with leg placement. Having only a couple of the legs touching the ground at the same time can create some interesting movement patterns.
• Buy a pack of jumbo- and regular-sized paperclips. For the US$2 you spend, you’ll be able to build a whole fleet of robots. I almost exclusively use paperclips and guitar strings for my creations.
• An assortment pack of heat shrink tubing goes a long way. Not only are your bots more interesting-looking, but you can use the tubing in key places to reinforce weak joints. I rarely have two strips of heat shrink on top of each other just for visual appeal.

This dual-motor vibrobot has the ends of paperclips soldered to two pager motors. Each motor is connected to a CdS cell so the more light each "eye" gets, the more the motor on that side fires. It's great to watch it react to a flashlight.

Resource List

Here are a few of the parts suppliers and websites that Zach (and I) recommend when planning out a BEAM project.

Solarbotics These guys are the go-to source for everything BEAM. I’ve been buying from them (and working with them) for many years and have always been impressed with their intense devotion to the BEAM hobby (and their customers).

Hobby Engineering Good source for motors, robot kits, parts, and other geekly goodies.

Goldmine Electronics I’ve never met a hardware geek who didn’t heart the Goldmine. If you’re not on their free catalog mailing list, get on it! It’s a treasure-trove of weird and wonderful parts and deep discounted gadgets.

Mouser Zach sez (and I concur): “Great for any extra parts you might need. You may be able to find parts a little cheaper elsewhere but I’ve found that their fast shipping and great packaging (every item comes in a clearly marked bag) makes it worth any savings you might find elsewhere.”

eBay Several good places in Hong Kong offer cheap LEDs via eBay.

Solarbotics.net The BEAM community portal. The Library section drops all sorts of mad science on BEAM theory and practice.

Beam-Online Another venerable and useful site for all things related to BEAM.

Zach’s BEAM Bots on Flickr To see additional (and hi-res) versions of these images, and Zach’s other bots, check out his Flickr page. To learn more about his design and fine arts work, visit his website.

This basic vibrobot uses a polyacene battery instead of a cap (to deliver about .6F of power). The bot gets a decent power burst when it fires. It also has a guitar string "nose" to help keep it away from larger bots.

 

Other Robot Projects from Street Tech

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• Zach Debord’s Twin-Engine Solarroller
• Gareth’s Coat Hanger Walker
• Gareth’s Mousey the Junkbot Page
• Mousey the Junkbot MAKE Project PDF
• Gareth’s MAKE Vol. 8 Pummer piece PDF (with Zach’s Pummers)
• Solarbotics Herbie the Mousebot Review
• Solarbotics Turbot Kit Review

  And you might also want to check out the companion site to my book, The Absolute Beginner’s Guide to Building Robots.

  [Robot illustration by Mark Frauenfelder]

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Sergei Pavlovich Korolev: The Soviet Space Program’s Secret Mastermind

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by Gareth Branwyn

On a cold, gray morning in October 1947, outside the Soviet city of Volgograd, a group of men watch in wonder as a huge rocket rumbles skyward from a hastily erected launch pad. Two years of intense effort to piece together a German V-2 rocket have finally paid off: The first Soviet ballistic missile has taken flight.

A stocky man in a dark leather coat is particularly enthusiastic. From this moment until his death, Sergei Pavlovich Korolev will be the moving force behind the Soviet space program. In only 10 years he and his team will stun the world with the launch of Sputnik, followed by a string of other historic firsts.

Yet Sergei Korolev will be forced to live a life in secret: Others will be given credit for some of his immense accomplishments. Even after his death in 1966, accounts of Korolev’s life will be clouded by hearsay, and official histories will obscure the true story of this remarkable man.

Born in Ukraine in 1907, Sergei Pavlovich Korolev became fascinated with aircraft at a very early age, watching planes at a naval airstrip near his home. In 1928 a 21-year-old Korolev entered Bauman Technical University to study aeronautical engineering; in 1931 he co-founded GIRD (Jet Propulsion Study Group), an unofficial organization experimenting with liquid fuel rockets.

Korolev was arrested by the Soviet secret police in 1938 during Stalin’s purges and was accused of “subversion in a new field of technology.” He was initially sent to the dreaded Kolyma gold mines in Siberia. But Stalin couldn’t afford to let his rampant paranoia slow down his engines of progress, so Korolev was transferred to a special prison for scientists and engineers where he was allowed to resume his rocket research.

After World War II, the engineer was sent to Germany to study captured V-2 technology, and was put in charge of a design bureau responsible for ballistic missiles. But inspired by the writings of Russian space visionary Konstantin Tsiolkovsky, Sergei set his sights higher than the battlefield. When a colleague questioned the military readiness of his rocket design, Korolev angrily replied: “The purpose of this rocket is to get there [pointing spaceward]. This is not some military toy!”

Korolev was the inexhaustible force behind a staggering number of space projects: the first intercontinental ballistic missile, first satellite, first man in space, first spacewalk, first spacecraft to impact the Moon, first craft to Venus, first Mars flyby, first spy satellite. James Harford, executive director-emeritus of the American Institute of Aeronautics and Astronautics, sums up this great engineer’s place in history: “Korolev dominated virtually the entire Soviet space program. His feats, and those of his design bureau, would have to be equated to those of dozens of U.S. space leaders, companies and NASA centers.”

Nov. 16, 1965, was to be the last launch date that Korolev would ever see. The Venera-3 probe was set on a course to Venus, to become the first craft to impact another planet. In January of 1966 Korolev checked himself into a hospital for a colon operation. Years of poor health brought on by harsh prison conditions and workaholism had taken their toll; Korolev died on the operating table. His Pravda obituary the next day was the first time Korolev was ever identified as the chief designer of Soviet space rocket systems.

Anatoly Abramov, who worked in Korolev’s design bureau, said of his former boss: “He was … an intellectual and a skilled craftsman. … While observing Korolev during our time together, I caught myself thinking he was from another planet … a character in a dream.”

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The following originally appeared in Discovery Online’s “Dead Inventors” column, March 1997]