stoica - Hybrid CA-Systems: Coupling Cellular Automata with...

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Hybrid CA-Systems: Coupling Cellular Automata with Artificial Neural Nets Christina Stoica www.cobasc.de Institute for Computer Science and Business Information Systems University of Duisburg-Essen Germany
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Hybrid Systems The nearly universal usability of cellular automata (CA) is well known. Models become still more powerful by coupling CA with artificial neural nets (NN). Such CA-NN-models may be called "hybrid systems" that contain certain characteristics of learning, adaptability and flexibility.
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First example SIMULATION OF TRAFFIC FLOWS Kohonen Feature Map The cells of the CA represent different types of cars regulates the special traffic lights
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Second Example NEURAL CA-SYSTEM The cells of the CA consist of Bi-directional Associative Memory-Nets (BAM) and a Kohonen Feature Map (KFM). models individual learning processes in dependency of a certain social milieu
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simulation of traffic flows - CA The cells of the CA represent different types of cars, i.e. different with respect to velocity and type of driving. These artificial cars move on different lanes of a highway. Because of the different velocities and types of driving accidents and other problems will occur that lead to backups. In particular, high density of traffic will increase the probability of accidents.
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simulation of traffic flows - CA Obstacle: If possible: overtake, else slow down Speed limit: adapt the speed The state of the cells is defined as: S = {0,1,2} 0 = speed up; 1 = overtake; 2 = adapt the speed ”Enlarged" Moore neighborhood i.e. two additional cells outside of the Moore neighborhood are taken into consideration. Is the cell on the right line, then consider only the cells at the front, on the left and the additional two cells on the left side.
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If car = right line then compute the state S t+1 : If R = set of all cells on the right line, then S ir R: If S ir > 4, then the car speeds up. If L = set of all cells on the left line, then apply for all S ir R: If S il > 4, then the car can overtake s ir t + 1 ( 29 = 0,if s kr t (29 4 k,r ( 29 R ir 1,if s kr t (29 4 s k,l t (29 4 k,l ( 29 k,r ( 29 R ir 2,if s ir t (29 4 s k,l t (29 4 k,l ( 29 k,r ( 29 R ir simulation of traffic flows - CA
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simulation of traffic flows In order to regulate the traffic and to avoid too many accidents the access roads to the highways are regulated by special traffic lights. These traffic lights stop the access if the density of traffic is too high and/or if there are already accidents with according backups.
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In the CA-model the traffic lights are regulated by a Kohonen feature map, which belongs to the type of non supervised learning nets. The net is trained to certain critical values of traffic density.
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This note was uploaded on 11/11/2011 for the course MATH 220 taught by Professor Kearn during the Fall '11 term at BYU.

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stoica - Hybrid CA-Systems: Coupling Cellular Automata with...

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