Subsumption architecture

Subsumption architecture is a methodology for developing Artificial intelligence robots. It is heavily associated with behavior based robotics. The term was introduced by Rodney Brooks and colleagues in 1986[1] [2]. Subsumption has been widely influential in autonomous robotics and elsewhere in real-time AI. The first journal publication mentioning the architecture, Brooks (1986), showed 3500 citations on Google Scholar as of October 2006.

## Contents

* 1 Description
* 2 Attributes of the architecture
* 3 References
* 4 See also
* 5 External links

## Description[edit | edit source]

A subsumption architecture is a way of decomposing complicated intelligent behaviour into many "simple" behaviour modules, which are in turn organized into layers. Each layer implements a particular goal of the agent, and higher layers are increasingly more abstract. Each layer's goal subsumes that of the underlying layers, e.g. the decision to move forward by the eat-food layer takes into account the decision of the lowest obstacle-avoidance layer.

For example, a robot's lowest layer could be "avoid an object", on top of it would be the layer "wander around", which in turn lies under "explore the world". The top layer in such a case could be "create a map", which is the ultimate goal. Each of these horizontal layers accesses all of the sensor data and generates actions for the actuators — the main caveat is that separate tasks can suppress (or overrule) inputs or inhibit outputs. This way, the lowest layers can work like fast-adapting mechanisms (reflexes), while the higher layers control the main direction to be taken in order to achieve the overall goal. Feedback is given mainly through the environment.

## Attributes of the architecture[edit | edit source]

The main advantages of the methodology are:

* the modularity,
* the emphasis on iterative development & testing of real-time systems in their target domain, and
* the emphasis on connecting limited, task-specific perception directly to the expressed actions that require it.

These innovations allowed the development of the first robots capable of animal-like speeds[3].

Main disadvantages of this model are:

* the inability to have many layers, since the goals begin interfering with each other,
* the difficulty of designing action selection through highly distributed system of inhibition and suppression, and
* the consequent rather low flexibility at runtime.

## References[edit | edit source]

Key papers include:

* R. A. Brooks (1986) "A Robust Layered Control System For A Mobile Robot", IEEE Journal Of Robotics And Automation, RA-2, April. pp. 14-23.
* R. A. Brooks (1987). "Planning is just a way of avoiding figuring out what to do next", Technical report, MIT Artificial Intelligence Laboratory.
* R. Brooks and  A. Flynn (1989), "Fast, cheap, and out of control: A robot invasion of the solar system," J. Brit. Interplanetary Soc., vol. 42, no. 10, pp. 478-485, 1989. (The paper later gave rise to the title of the film Fast, Cheap and Out of Control, and the paper's concepts arguably have been seen in practice in the 2003/4 Mars Exploration Rover Mission.)

1. ↑ Brooks, R. A., and J. Connell, "Asynchronous Distributed Control System for a Mobile Robot", Proceedings of SPIE's Cambridge Symposium on Optical and Optoelectronic Engineering, Cambridge, MA, October 1986, pp. 77–84.
2. ↑ Brooks, R. A., "A Robust Programming Scheme for a Mobile Robot", Proceedings of NATO Advanced Research Workshop on Languages for Sensor-Based Control in Robotics, Castelvecchio Pascoli, Italy, September 1986.
3. ↑ Brooks, R. A., "Elephants Don't Play Chess", Robotics and Autonomous Systems (6), 1990, pp. 3–15.

## See also[edit | edit source]

* robotic paradigms
* agent architecture
* behavior based AI
* behavior-based robotics
* cognitive architecture
* emergent behavior
* scruffies
* situated

## External links[edit | edit source]

* Subsumption Behaviors used for a Variety of Real World Tasks
* SB-MASE is a subsumption-based multi-agent simulator.
* Subsumption for the SR04 and jBot Robots , DPRG website