Allen (robot)
Encyclopedia
Allen was a robot
introduced by Rodney Brooks
and his team in the late 1980s, and was their first robot based on subsumption architecture
. It had sonar
distance and odometry
onboard, and used an offboard lisp machine
to simulate subsumption architecture. It resembled a footstool on wheels.
Allen used three layers of control which are implemented in subsumption architecture. "The lowest layer of control makes sure that the robot does not come into contact with other objects." Due to this layer it could avoid static and dynamic obstacles, but it could not move. It sat in the middle of the room, waiting for obstruction. When the obstruction came, Allen ran away, avoiding collisions as it went. It used following internal representation
, and every sonar return represented a repulsive force with, and inverse square drop off in strength. Direction of its move was obtained by sum of the repulsive force
s (suitably thresholded). It possessed an additional reflex which halted it whenever it was moving forward, and something was directly in its path.
"The first level layer of control (second layer), when combined with zeroth, imbues the robot with the ability to wander around aimlessly without hitting obstacles." Owing to the second layer, Allen could randomly wander about every 10 seconds. It used simple heuristic
, which was coupled with the instinct to shun barriers by vector addition. "The summed vector suppressed the more primitive obstacle avoidance vector, but the obstacle avoidance behaviour still operated, having been subsumed by the new layer, in its account of the lower level's repulsive force. Additionally, the halt reflex of the lower level operated autonomously and unchanged."
The third layer made the robot try to explore. Allen could look for distant places (with its sonars), then tried to reach them. "This layer monitored progress through odometry, generating a desired heading which suppressed the direction desired by the wander layer. The desired heading was then fed into a vector addition with the instinctive obstacle avoidance layer. The physical robot did not therefore remain true to the desires of the upper layer. The upper layer had to watch what happened in the world, through odometry, in order to understand what was really happening in the lower control layers, and send down correction signals."
Robot
A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...
introduced by Rodney Brooks
Rodney Brooks
Rodney Allen Brooks is the former Panasonic professor of robotics at the Massachusetts Institute of Technology. Since 1986 he has authored a series of highly influential papers which have inaugurated a fundamental shift in artificial intelligence research...
and his team in the late 1980s, and was their first robot based on subsumption architecture
Subsumption architecture
Subsumption architecture is a reactive robot architecture heavily associated with behavior-based robotics. The term was introduced by Rodney Brooks and colleagues in 1986...
. It had sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
distance and odometry
Odometry
Odometry is the use of data from moving sensors to estimate change in position over time. Odometry is used by some robots, whether they be legged or wheeled, to estimate their position relative to a starting location. This method is sensitive to errors due to the integration of velocity...
onboard, and used an offboard lisp machine
Lisp machine
Lisp machines were general-purpose computers designed to efficiently run Lisp as their main software language. In a sense, they were the first commercial single-user workstations...
to simulate subsumption architecture. It resembled a footstool on wheels.
Allen used three layers of control which are implemented in subsumption architecture. "The lowest layer of control makes sure that the robot does not come into contact with other objects." Due to this layer it could avoid static and dynamic obstacles, but it could not move. It sat in the middle of the room, waiting for obstruction. When the obstruction came, Allen ran away, avoiding collisions as it went. It used following internal representation
Representation
Representation can refer to:* Representation , one's ability to influence the political process* Representative democracy* Representation, a type of diplomatic mission...
, and every sonar return represented a repulsive force with, and inverse square drop off in strength. Direction of its move was obtained by sum of the repulsive force
Repulsive force
Repulsive force may refer to:* A repulsive force of an Accelerating universe, which according to certain theories causes planets and matter to get farther and farther apart* Like charges repelling according to Coulomb's law...
s (suitably thresholded). It possessed an additional reflex which halted it whenever it was moving forward, and something was directly in its path.
"The first level layer of control (second layer), when combined with zeroth, imbues the robot with the ability to wander around aimlessly without hitting obstacles." Owing to the second layer, Allen could randomly wander about every 10 seconds. It used simple heuristic
Heuristic
Heuristic refers to experience-based techniques for problem solving, learning, and discovery. Heuristic methods are used to speed up the process of finding a satisfactory solution, where an exhaustive search is impractical...
, which was coupled with the instinct to shun barriers by vector addition. "The summed vector suppressed the more primitive obstacle avoidance vector, but the obstacle avoidance behaviour still operated, having been subsumed by the new layer, in its account of the lower level's repulsive force. Additionally, the halt reflex of the lower level operated autonomously and unchanged."
The third layer made the robot try to explore. Allen could look for distant places (with its sonars), then tried to reach them. "This layer monitored progress through odometry, generating a desired heading which suppressed the direction desired by the wander layer. The desired heading was then fed into a vector addition with the instinctive obstacle avoidance layer. The physical robot did not therefore remain true to the desires of the upper layer. The upper layer had to watch what happened in the world, through odometry, in order to understand what was really happening in the lower control layers, and send down correction signals."
See also
- Artificial lifeArtificial lifeArtificial life is a field of study and an associated art form which examine systems related to life, its processes, and its evolution through simulations using computer models, robotics, and biochemistry. The discipline was named by Christopher Langton, an American computer scientist, in 1986...
- Artificial intelligenceArtificial intelligenceArtificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...
- Distributed artificial intelligenceDistributed artificial intelligenceDistributed artificial intelligence is a subfield of artificial intelligence research dedicated to the development of distributed solutions for complex problems regarded as requiring intelligence...