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This document (created Oct 5, 1996) is intended to serve as an immediate resource for those interested in BEAM robotics. The latest and original version of this FAQ (Frequently Asked Questions) can always be found at http://people.ne.mediaone.net/bushbo/beam/FAQ.html. If you have suggestions and comments write me at bushbo@mediaone.net. Thanks.
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Table of Contents

[1] What is BEAM robotics?
[2] What is a simple example of BEAM robotics?
[3] What is a Nervous Network?
[4] What is a Microcore?
[5] What are Hextile boards?
[6] Is there a mailing list?
[7] Is the mailing list archived?
[8] What publications are available that discuss BEAM robotics?
[9] Where can i find electronic and mechanical parts?
[10] What are the skills required to build BEAM machines?
[11] What kind of technology is in these machines?
[12] What is the next step in the evolution of BEAM robotics?
[13] What are some cool web sites to check out?
[14] Upcoming Events, Competitions and Meetings
[15] Are there any BEAM Robotics groups?
[16] When is Mark W. Tilden publishing his books?
[17] A Course of Study in BEAM Robotics?
[18] Acknowledgements

[1] What is BEAM robotics?

BEAM is a acronym standing for:

Biology, Electronics, Aesthetics and Mechanics

The basic principles of BEAM rest on the fact to build smart machines one must first build a smart body. Forget the brain, let us just focus on a simple stimulus-response based ability within a machine. In it's shortest form is:

  • Use minimalist electronics (keep it simple, reduced parts count)
  • Recycle & Reuse components out of technoscrap
  • Use solar power, if possible
More elaborately, from the father of BEAM robotics:
...The science behind the idea stems from current concepts in artificial intelligence (AI), artificial life (ALife), evolutionary biology, and genetic algorithms. It seems that building large complex robots hasn't worked well, so why not try to evolve them from a lesser to a greater ability as mother nature has done with biologics? The problem is that such a concept requires self-reproducing robots which won't be possible to build (if at all) for years to come. A solution, however, is to view a human being as a robot's way of making another robot, to have an annual venue where experimenters can let their creations interact in real situations, and then watch as machine evolution occurs. In other words, robogenetics through robobiologics.

-Mark W. Tilden

other philosophical views:
Dave Hrynkiw and Andrew Miller

[2] What is a simple example of BEAM robotics?

The simplest of BEAM robots can be constructed around a two-transistor circuit, called a relaxation oscillator, which is powered by light and twitches with movement. The most complicated part of constructing these critters is in the creativity of recycling junk parts into your design. Here are some plans:

  • The solar engine write-up by Brian Bush (me).
  • BEAM solar engine plans - rather old version, but it encapsulates the basic idea.
  • This set of plans contains the basic solar engine circuit and also the physical layout to free-form a solar engine (it is right above the circuit diagram).
For some ideas on mechanical layout and structure, see the Solarbotics picture archive of BEAM machines.

[3] What is a Nervous Network?

A real-time non-linear analog control system emulating a low-level peripheral spinal system. Based on arrays of sequential RC (Resistor-Capacitor)-time-based pulse delay circuits in closed loops, a Nv net is any circuitry that can act as a media for sustaining independent control "processes."

-Mark W. Tilden

The individual "neurons" are based on self-reseting differentiators with an avalanche gain greater than their decay value. The "networks" are simply these neurons connected in the loops whose patterns are laid out in the paper, Living Machines.

An excerpt from "Biomorphic Robots and Nervous Net Reasearch: A New Machine Control Paradigm" by Mark W. Tilden:

Nervous Net (Nv) technology is a non-linear analog control system that solves real time control problems normally quite difficult to handle with digital methods. Nervous nets are to Neural nets the same way peripheral spinal systems are to the brain. This work has concentrated on the development of Nv based robot mechanisms with electronic approximations of biologic autonomic and somatic systems. It has been demonstrated that these systems, when fed back onto themselves rather than through a computer-based pattern generator, can successfully mimic many of the attributes normally attributed to lower biological organisms. Using Nv nets, highly successful legged robot mechanisms have been demonstrated which can negotiate terrains of inordinate difficulty for wheeled or tracked machines. That non-linear systems can provide this degree of control is not so surprising as the part counts for successful Nv designs. A fully adept insect-walker, for example, can be fully controlled and operated with as little as 12 standard transistor elements.

See below for more information. For information on constructing such a device, see What is a MicroCore? and the BEAM Tek page on nervous networks.

[4] What is a Microcore?

Generic term for the closed-loop implementation of a nervous net responsible for direct actuator control in a Biomech robot. The term Microcore generically refers to any Nv core greater than equal to four, but specifically such cores are described by a numeric prefix. They are, in order, Monocore, Bicore, Tricore, Quadcore (the most common form of Microcore), Quincore, Hexcore, Septcore, Octacore, etc.

[5] What are Hextile boards?

The Hextile is a Nv specific protoboard designed to take advantage of various symmetries in Nv circuitry with tons of spare pads for additional circuitry, sensors, and mounts. The Hextile boards were made in several variations as a research tool, by and for Mark W. Tilden.

Hextile boards are single sided square and hexagonal boards that come pre-arranged in sheets to provide the most convenient collections of biomech components for walkers, etc. There are over seven different sets of them now and, alas, even the cheapest of them costs between three and nine dollars per single board, up to $98 per sheet (quantity 50 x 30 boards each, so that's with the discount).

The black substrate used makes the devices easy to debug for shorts and evaporates moisture away quickly (for washing away water-soluble flux), while the triple-thick gold clading makes for high reliability and easy soldering. The boards are not just component holders but designed as structural elements to hold the robots together with the smallest and most reliable adhesive currently known: 60-40 solder (Tilden's experience).

Tilden designed them like this so they'd be easy to work with, cool to display, easy to connect, and so they'd last. When you're talking bugs with a 10 year life expectancy, you want your controllers to be the least of your problems. So far, that's been the case.

Details on these boards will be included in the upcoming book Principa Robotica with a detailed explanation on what does what and why. They will become public domain after the publication, but not now only because the documentation isn't finished yet. If it works out, Tilden is hoping hextiles will be a stock item with one or more of the BEAM saleshouses. A picture of Hextile Nv board (Hx 1.0) along with a Driver Hextile (Dx 1.1) that compose Bigfoot is here.

Aside from the Hextile (Hx 1.0) Nv board itself, there is also:

The low-power Driver Hextile [lDx 1.0]:
Containing circuitry specific to my micro-power transistor H-bridge and (gak!) Happy Birthday Controller module timer (now very, very, very obsolete).

The Driver Hextile [Dx 1.0 and 1.1]:
A general purpose motor and etc. driver board using the 74245 Octal Driver. The 1.1 features better use of the chip enable so that such boards can be stacked to act as motor multiplexers.

The Square Hextiles [Sx and '+']:
The Sx board is a square Nv hextile which can fit along on of the edges of a regular, larger hexagonal tile. The '+' board is a 4 or 8 element switch device for sensors and microswitches.

The Tri Tiles ['cm' and 'sw']:
Two triangular boards, the first a Capacitor Module (cm), and the second a single Switch Module (sw), compatable to the edges of hexagonal tiles.

The Edge Tiles:
Designed to act as power and signal bridges along the edges of joined hextiles.

The Pentagonal Tile [Px]:
Designed as a LED, switch and power board, it exists to complete the full range of geometric primitives in the Hextile line.

The Hx range of boards were designed for modular experiments in Nv topological connections i.e.: how to connect Nv circuitry together to build more capable brains and bodies, and have been the staple tools of my Nv work for the past two years. Hx tiles can be assembled into any structure known to Euclidian geometry, and are sturdy enough to mount both electronics, battery, sensor, and motor mechanics right on the boards.

[6] Is there a mailing list?

Yes, there is a BEAM Mailing List. You can send Subscribe and Unsubscribe by sending an email to the following address:


and then enter the following line in the body of the message:

subscribe beam _your_email_address_here_
To unsubscribe, simply send an email to the same address above with the body containing the message:
unsubscribe beam _your_email_address_here_

There are over 300 people now on the list, from all over the world. If there are any questions about this email list, please see this document About the BEAM e-mail list by Mark Dalton mwd@cray.com.

[7] Is the mailing list archived?

Yes, the current mailing list archive is at http://www.webconn.com/~mwd/beam/mlist/beam/beam.html. There is also an old archive has messages up to late 1997, which is somewhat useful for those wishing to browse old articles. The old archive is at http://www.webconn.com/mail/beam/ and is archived by thread. Messages before July, 1997 are here.

Search the List

You can search the mailing list archive by using a search engine, such as Hotbot with the following parameters Modify-must contain "BEAM", the Location-CyberPlace "www.webconn.com" and enter your search text (e.g., Solar). This basically narrows the search domain to the www.webconn.com domain (and only documents that contain beam@webconn.com, such as the archived list emails).

[8] What publications are available that discuss BEAM robotics?

[9] Where can i find electronic and mechanical parts?

  • Junk yard, back alley, on trash day... you get the idea
  • Your local surplus store
  • A list of vendors I use often
  • Solarbotics - Kits with step-by-step instructions and all of the parts you need.
  • On-line resources - Magazines, newsletters, Electronic/mechanical parts and surplus stores on-line.
  • Where to get or find parts and motors
  • Mondo-tronics' Robot Store, has Nitinol Kits, 1995 BEAM Games Guidebook and Solaroller do-it-yourself kits.

    There are many sources for BEAM parts. The best way is to just start collecting techno-scrap (printers, floppy drives, etc). You can also keep an eye on wholesale distributors for good prices on stuff. Below is a list of some parts for major components (and some sources) needed to build a BEAM walking machine (and other BEAM bots).

    Structural / Exoskeleton:

    • Copper Clad Carbon Steel (1/6" - 3/32") - from a local welding supplier
    • plain copper wire (14-12 gauge) - swiped from junk, like an old refrigerator temperature sensor line
    • other metals: brass and nickel
    • paper clips

    Power (supply, storage):
    • solar cells - calculators
    • Some (small) photovoltaic sensors (e.g., 0.4V each) can be used to generate power when combined in series
    • capacitors - such as a 1 Farad capacitor to store collected energy

    Control related:
    • Integrated circuits, such as
      • 74x14 - hex inverter, the main part of an nv network
      • 74x139 - used as a dual decoder to avoid the double-trigger and then smoke (!) feature of Tilden's H-bridge
      • 74x240 - octal buffers and line drivers with 3-state outputs
      • 74x244 - a non-inverting buffer-it has a pair of directional enable lines-which lend itself to being used as a multiplexer, sort of a DPDT electronic switch
      • 74x245 - an octal bus tranciever designed for data transmision, but used as motor drivers
    • Resistors - Make your first MicroCore with 'larger' values like 0.22uF caps and 10.0 megaOhm resistors.
    • Capacitors - Make sure that you are using non-polarized caps; "monolithic" work well as they are fairly small. 0.1 microfarad and 0.22 microfarad are two values that work well. Resist the temptation to use larger capacitors.
    • Signal diodes
    • Low-current LEDs, get a handfull of low-current LED's to use for debugging. These are the LED's that operate at 1.0 to 2.0 mA instead of 10 to 20 mA. Use larger than usual current limiting resistors for the LED's.

    Movement related:
    • Magnets
    • Coils
    • Brass wheels and pulleys
    • Motors (preferably with gearheads)
    • Gearheads
    • Pager motors
    • Oven Timer Units (OTUs) - tutorial on OTU usage by Dave from Solarbotics
    • Clock steppers (a "one-phase stepper", give it a square wave from a a BiCore, and it spins)
    • ...and other watch movements
    • Casette player parts
    • Dubro wheel collars or Ball-links - for connecting motors to legs (Richard Weait's find)

    • Touch sensors (antenna-see picture for construction details):
      • Heat shrink tubing 1/16"
      • Augat sockets
      • Resistors - could be used as part of the sensor mechanics

      • ...and for the touch sensor itself try any of the following (small guage for photovore feelers, larger guage for walkers):
      • Springs
      • Piano wire - You can get find it in most hardware stores (in various gauges)
      • Guitar strings - Martin guitar strings make a silver alloy string that solders nicely

    • Light sensors
      • CdS cells - resistive light sensors
      • Photodiodes - (still working on figuring out how to connect easily with minimal parts to Nvs)

    • Tilt sensors
      • mecury switches - maybe configured to activate the reverse switch, if terrain gets too steep

    Supplies and Tools:
    • Sewing machine oil as a lube
    • Old toothbrushes for cleaning
    • Excessive solder as universal adhesive
    • Kester #31, Hydo-X by Multicore or other water soluble solder so flux won't scrunch your gears. Also the MicroCore is sensitive to resistances in the MegOhms so as a result things such as solder flux can cause a slightly conductive path on your circuitry
    • Helping hands to hold your small circuits while under construction
    • Wooden clothespins - for holding parts while working on them

  • [10] What are the skills required to build BEAM machines?

    Mechanical skills
    • Construction skills
    • Solarbotics - Pictures of what others have built to spark your imagination.
    • Miller's Leg Mechanics
    and, of course patience.

    [11] What kind of technology is in these machines?

    Simple, yet elegant solutions: "a variety of robotic devices with adaptive nervous systems not exceeding the equivalent of 10 neurons. These devices not only learn to walk from first principles but can also adapt to many different circumstances including severe personal damage. There are no processors involved; my most complex device uses only 50 transistors for its entire spectrum of behavior, response and control."

    -Mark W. Tilden,
    Biologically Plausible Dynamic Artificial Neural Networks Reviewed,
    January 1993

    "any of a variety of transistors, common hex-inverters, and/or inverting bus drivers, ranging in price from 8 cents to $1.24."

    -Mark W. Tilden

    [12] What is the next step in the evolution of BEAM robotics?

    Here are some ideas off of the BEAM mailing list and from Tilden himself:
    • Vision. Mark's (Tilden) been doing some neat work with foviation, building light-seeking vision/head mechanisms powered by Nv technology.

    • Hygene. If you consider the problems of an autonomous machine with an extreme lifetime, the big question is how to keep yourself clean so that your performance remains constant. The sleek look and grooming habits of insects is to optimise this characteristic. We can make machines robust against such things (teflon wire insulation on many surfaces), but what does this mean when you've got dirt splattered on your sensors? Make a machine that can negotiate mud in the rain and still keep track of itself, and you're well on the way to an advanced life form.

    • More recently Tilden has been doing some advanced work into the nature of minimal cognitive architectures. Better brains for BEAM bodies involving Nv arrays, some with hundreds of neurons. The resulting robots will be... big.

    [13] What are some cool web sites to check out?

    [14] Upcoming Events, Competitions and Meetings

    • Robots from Rubbish from Wired Magazine.
    • April 16th - April 18th, 1998 - BEAM Workshop in Los Alamos (at Los Alamos High school) [10:00AM - 4:00PM] note: no entrance fee.
    • March-April 1998 issue of the American Scientist magazine - Brief article entitled "Little Robots in Space," which is about inexpensive satellites that are being built and experimented with by a group of three scientists: Kurt Moore, Janette Frigo and Mark W. Tilden.
    • Spring, 1998 - Glasgow, Scottland - Robotix (no other info on this event)
    • Monthly - Northern New Mexico Robotics meeting. Contact Mark W. Dalton at mwd@cray.com.
      Passed events:
    • 1996 BEAM Robotics Workshop - passed
    • May, 1997 - Western Canada Robotic Games - passed
    • June 21st - 22nd, 1997 - 1st Annual Taos Solar Festival - passed
    • June 23rd - July 13th, 1997 - Neuromorphic Engineering - see Learning in Behaving Systems and Neurobots - passed
    • July, 1997 - Article in next upcomming National Geographic
    • July, 1997 - Article in Nuts & Volts on the Solarbotics Photopopper
    • August 9, 1997 - Toronto BEAM get together [12:00 noon - 5:00 p.m] - Contact Richard Weait at crs0274@inforamp.net - passed
    • November, 1997 - International BEAM Games at Lucknow, India - http://www.webconn.com/~mwd/beam-india.html - passed
    • March 10, 1998 - CNN story on Tilden's work and terrorism detection - passed
    • March 15, 1998 - Robots Rising on the Discovery Channel (US), a feature program on robots (including our Mark Tilden), the show will be repeated

    [15] Are there any BEAM Robotics groups?

  • Winnipeg Area Robotics Society
  • If anyone wants to list themselves here to hold some group meeting, or build-fest, email me contact information and city. A listing of people interested in forming a BEAM group in their area is here.

  • [16] When is Mark W. Tilden publishing his books?

    Tilden is coming out with two books in the next year (editors willing):
    • Living Machines, MIT Press. Primarily a philosophy book with some plans.
    • Principia Robotica, MIT Press. BEAM engineering tech with examples.

      (And Pending)

    • A Dream of Stars, Blantine books. Fiction - Tilden's first attempt at BEAM Sci-fi.
    • Explorations in the Robot Jurassic Park, MIT Press. Primarily a coffee-table gloss-picture book of Tilden's designs.
    Can't wait, well the following is a section on
    Biomech Motor Bridges from a draft of the book, Principia Robotica. Hope to have a Table of Contents up here when it gets to me, so watch this space.

    [17] A Course of Study in BEAM Robotics?

    A good course of study to those just beginning in BEAM robotics might be:

    Of course, this is only my opinion, but it begins with the simple and moves to increasingly complex designs. In all, start simple and work your way up. Since practice makes (*almost*) perfect, build, build and build. All along you should continuously search for parts and junk. I have always found a good way to build neat devices is take mechanisms you find in nature and in high-tek and try to replace them with nervous networks and solar engines. Example: a stepper motor usually has a computer as a controller. Why? Well because of the somewhat complicated patterns needed to drive the motor it is usually easier produced by a computer (program). The action of controlling a stepper motor can be performed by loops of nervous networks. Of course, this is not the most efficient manner, but it can be done. You will be amazed at the type of behavior you can get from simple loops of circuits, and it doesn't always have to be formed or embedded as a robot.

    Always buy sets of things, so you can experiment and sometimes unfortunately destroy parts. Note: I am assuming you know basic electronics (see Forrest Mimms' Basic Electronics) and how to solder.

    The following is a simple procedure that can be applied to most endeavors:

    • do simple things first
    • learn to do them flawlessly
    • add new layers
    • don't change the simple things
    • make the new layer work as flawlessly as the previous layer
    • repeat

    [18] Acknowledgements

    Thanks to those who responded with updates, new material, corrections, suggestions and etc. I (Brian) personally would like to thank the following individuals, since my own work in BEAM robotics has been enhanced by their contributions. Note: some of the names are indirect; that is, they replied to queries on the Beam mailing list:

    Mark W. Dalton, mwd@cray.com
    Andrew Miller, andr106@ibm.net
    Dave Hrynkiw, dave@solarbotics.com
    Richard Weait, crs0274@inforamp.net
    John A. deVries II, zozzles@lanl.gov
    Steven Bolt, sbolt@xs4all.nl
    Terry Newton, wtnewton@nc5.infi.net
    Gene Kwiecinski, gene.kwiecinski@factory.com
    Rick Diaz, richard.diaz@lcra.org 
    and the man behind the machines Mark W. Tilden, mwtilden@lanl.gov
    along with others on the BEAM email list.

    Copyleft 1996-1998, Brian O. Bush

    Brian O. Bush / bushbo@mediaone.net
    Updated: December 10th, 1998

    Back to my synthetic life page.