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2003 BEAM Photovore Competition Rules & RegulationsRules & Regulations (Same as 2002) Last modified on February 4, 2002

Originally Created by Dr. Mark Tilden
Rules adapted for BEAM/WCRG Games by Dave Hrynkiw

Official PDF Version of the Rules

Note: The following is an extract of the official PDF version above. Competitors are strongly suggested to use the above PDF as your guidelines.

Object:

Within a 150mm (6") cube, build a device that is self contained, solar powered, and goal seeking. The robot competitor will have to face off against other devices in a well-lit competition area, having to avoid obstacles and race to the middle. Once there, have your robot dominate the light pool until the end of the 5 minute round. First to the center circle wins a half point, and the one closest to the very center at the end of round wins a full point.

Background:

If you tie two solarollers together and direct their solar cells at different angles, you will notice that your new creature will do one of two things; run away from light sources or run towards them. A similar observation, made by Valentino Braitenberg in his book "Vehicles-Experiments in Synthetic Psychology" (ISBN: 0-262-52112-1), classified a large number of two wheeled devices which existed on a theoretical plane. He noticed that devices that follow light can be thought of as "aggressive" as they charge the light source in an attempt to destroy it, where as devices that run from light slow down in the dark and can be thought of as "submissive". The first class of devices can technically be called "phototropic" because they mimic plants in their sun-following abilities, and the second as "photophobic", as they exhibit behavior that shuns light like a mushroom. Braitenberg's book goes on to describe many classes of such devices, each featuring astonishing behavioural complexity depending on the style and position of sensors, motors and simple internal wiring. An excellent synopsis of the theory was presented in the March 1987 Scientific American in Computer Recreations by A. K. Dewdney should the book "Vehicles" be hard to find (which has been since released in paperback by MIT press).

A "Photovore" (literally, Greek for "light-eater") absorbs ambient light, converting it directly to electro-mechanical energy; a significant improvement over mother nature who can only do this in living creatures through an intermediary chemical stage. The most basic Photovore is simply two Solarollers joined together, with solarcells swapped over to each other's side.

The knowledge of such vehicles is years old, but it has only been recently that work in behavior-based robotics has given such devices more credence. Mr. Mark Tilden (BEAM Founder) took the minimalist approach to robotics that first started with Professor Rodney Brooks of MIT, and built some very capable meso-scale legged robots. His shoebox-sized robots do not have a "world memory" that defines the shapes in the environment the robot lives in. Rather, his devices respond to their environment by direct stimulus-response, That is, these creatures don't have a complex internal world model, but simple reaction sets to changing exterior states. Machines built so far on this principle have proven abilities that match or exceed those using traditional computer and microcontroller approaches. For example, Mr. Tilden's $400 Unibug Walker (about 6" square in size) can easily traverse thick shag carpeting and grass, and negotiate complex terrain without falling or getting trapped. On the other hand, in 1988 the American Department of Defense (DoD) finally finished a six legged walking truck called the Adaptive Suspension Vehicle for eight million dollars which would mindlessly walk off a cliff. The first used behavioral science, the second an extremely complex multi-processor computer system.

The BEAM supposition is that processors may be completely unnecessary, and that simple, symmetric electronics coupled with clever mechanical designs can produce devices that can "survive" in real-world environments, and maybe more. Simulations are unreliable, computers on wheels have difficulty surviving in complex environments, and Artificial Intelligence systems are too large and unwieldy to mount in small robots. Thus BEAM is at least one answer to evolve generations of stimulus based devices that, like the first protozoa on earth, must compete to survive.

Competition Design Parameters:

1 - The competing device must initially fit within the boundaries of a 150mm (6") cube. During competition, robot devices may vary their geometry as necessary but cannot deliberately leave any part of themselves behind. Competing devices must finish with all that they started with, although they may add to their mass if able.

2 - No batteries (rechargeable or otherwise) are be allowed on the photovore competitor, only verifiable electrical capacitors. Batteries (even nicads) have an inherent residual charge left in them, even after they've been run down. This residual charge would be an unfair advantage on the field of competition. No other form of power source (chemical, mechanical, animal, etc.) is allowed. Spring energy may be utilized only if the spring is energized only by the means of the energy produced via the solar cell after the start of competition. The competitor must extract all the energy it uses from solar cells on its chassis. There is a solar cell size restriction of 2442 square millimeters.

3 - Devices are forbidden to exhibit deliberately destructive behavior (saw blades, cutters, electro-shock devices, etc.) towards other robotic competitors. All interactions between devices should be on the order of a pushing/grappling match.

4 - Although devices are allowed to touch or follow internal walls and hazards, they are forbidden to intentionally damage the "world" in any way (beyond expected norms). Any device exhibiting such behavior will be disqualified and removed from play.

Platform Details - The Photovore Arena:

The arena will be a level surface constructed of 5/8" white Melamine or light-brown MDF construction particle-board. It will have dimensions of approximately 620mm (24.4") square, with 80mm (3.15") tall, 37mm (1.5") diameter wooden dowel posts painted black placed in four equidistant locations in the arena.

The arena will be illuminated by a single 250 watt halogen lamp mounted in a standard Luxo-Lamp style fixture (the Satco Halogen double-envelope clear Bulb S3475 considered the norm). This fixture will be located and aimed directly down towards the center of the goal circle from an elevation of 300mm to the bulb tip. The goal circle is 150mm in diameter with a dot indicating middle, located in the center of the arena.

Each of the competitor robots can start from any of the four 150mm corner squares. The competitor must fit fully within the starting square, and provision must be made to ensure the device is at zero stored-energy potential at the time of event start. The initial orientation of the robot is to be entirely determined by the competitor at the start of the event.

The robots will have to contend with the four black posts mounted on the arena, and the shadows they cast. The posts will be mounted so tactile sensors will not have any cracks to be lodged in.

The goal circle and starting squares are marked with a 1mm black ink "Sharpie" marker.

Photovore Competition Procedure:

At the time of competition, the robots will be placed in competitor-selected starting squares, and the energy "kill" mechanisms put in place. At the judge's indication, the kill mechanisms are disabled and the timer started.

The first robot to cover the dot in the middle of the goal circle with a part of it's body will be awarded a ½ point. Passing a sensor flagella or sensor stalk over the dot does not constitute covering the dot. If neither robot successfully covers the goal circle dot, the ½ point will not be awarded.

At the end of the 5 minute round, the robot nearest to the goal circle dot will be awarded a full point. Distance will be measured from the geometric centre of the robot to the goal circle dot.

The robots cannot be interfered with in any way until the round finishes at the end of the 5 minutes, unless if the judge rules that the round has come to a definite conclusion. This covers contingencies such as both robots stalling, or a robot failing in the starting square.