BEAM robotics (from biology, electronics, aesthetics and mechanics) is a style of robotics that primarily uses simple analogue circuits, such as comparators, instead of a microprocessor in order to produce an unusually simple design. While not as flexible as microprocessor based robotics, BEAM robotics can be robust and efficient in performing the task for which it was designed.
BEAM robots may use a set of the analog circuits, mimicking biological neurons, to facilitate the robot's response to its working environment.
Mechanisms and principles
The basic BEAM principles focus on a stimulus-response based ability within a machine. The underlying mechanism was invented by Mark W. Tilden where the circuit (or a Nv net of Nv neurons) is used to simulate biological neuron behaviours. Some similar research was previously done by Ed Rietman in 'Experiments In Artificial Neural Networks'. Tilden's circuit is often compared to a shift register, but with several important features making it a useful circuit in a mobile robot.
Other rules that are included (and to varying degrees applied):
Use the lowest number possible of electronic elements ("keep it simple") Recycle and reuse technoscrap Use radiant energy (such as solar power)
There are a large number of BEAM robots designed to use solar power from small solar arrays to power a "Solar Engine" which creates autonomous robots capable of operating under a wide range of lighting conditions. Besides the simple computational layer of Tilden's "Nervous Networks", BEAM has brought a multitude of useful tools to the roboticist's toolbox. The "Solar Engine" circuit, many H-bridge circuits for small motor control, tactile sensor designs, and meso-scale (palm-sized) robot construction techniques have been documented and shared by the BEAM community.
BEAM robots
Being focused on "reaction-based" behaviors (as originally inspired by the work of Rodney Brooks), BEAM robotics attempts to copy the characteristics and behaviours of biological organisms, with the ultimate goal of domesticating these "wild" robots. The aesthetics of BEAM robots derive from the principle "form follows function" modulated by the particular design choices the builder makes while implementing the desired functionality.
Disputes in the name
Various people have varying ideas about what BEAM actually stands for. The most widely accepted meaning is Biology, Electronics, Aesthetics, and Mechanics.
This term originated with Mark Tilden during a discussion at the Ontario Science Centre in 1990. Mark was displaying a selection of his original bots which he had built while working at the University of Waterloo.
However, there are many other semi-popular names in use, including: Biotechnology Ethology Analogy Morphology Building Evolution Anarchy Modularity
Microcontrollers
Unlike many other types of robots controlled by microcontrollers, BEAM robots are built on the principle of using multiple simple behaviours linked directly to sensor systems with little signal conditioning. This design philosophy is closely echoed in the classic book "Vehicles: Experiments in Synthetic Psychology". Through a series of thought experiments, this book explores the development of complex robot behaviours through simple inhibitory and excitory sensor links to the actuators. Microcontrollers and computer programming are usually not a part of a traditional (aka., "pure" ) BEAM robot due to the very low-level hardware-centric design philosophy.
There are successful robot designs mating the two technologies. These "hybrids" fulfill a need for robust control systems with the added flexibility of dynamic programming, like the "horse-and-rider" topology BEAMbots (e.g. the ScoutWalker 3). 'Horse' behavior is implemented with traditional BEAM technology but a microcontroller based 'rider' can guide that behavior so as to accomplish the goals of the 'rider'.
Types
There are various "-trope" BEAMbots, which attempt to achieve a specific goal. Of the series, the phototropes are the most prevalent, as light-seeking would be the most beneficial behaviour for a solar-powered robot.
Audiotropes react to sound sources. Audiophiles go towards sound sources. Audiophobes go away from sound sources. Phototropes ("light-seekers") react to light sources. Photophiles (also Photovores) go toward light sources. Photophobes go away from light sources. Radiotropes react to radio frequency sources. Radiophiles go toward RF sources. Radiophobes go away from RF sources. Thermotropes react to heat sources. Thermophiles go toward heat sources. Thermophobes go away from heat sources.