Generation Control Table
The Generation Control table controls how the GA will create
each new generation from the current generation. The columns in the table
are:
- Number of Iterations—This
is the number of generations that will be simulated
- Percent Reproduction—This
is the percentage of the previous generation’s accelerometer sets that
will be directly reproduced (copied) into the new generation. For the
example shown, the best 10% of accelerometer sets (those with the lowest
cost) will be directly carried over (reproduced) into the next generation.
As long as the Percent Reproduce parameter is non-zero the minimum
cost for each generation is guaranteed to never increase from one generation
to the next.
- Percent Mutation—This
parameter determines how many gene sequences in the new generation will
be created by mutating genes (DOF) of an old gene sequence (DOF set).
A mutation is where some DOF of an accelerometer set are randomly changed.
The percentage of DOF for a specific accelerometer set that will be mutated
is controlled by the Mutation Control parameter. For the example
in Figure 15, 40% of the accelerometer sets
in the new generation will be created by selecting accelerometer sets
from the current generation and randomly changing 5% of the DOF. The lower
the cost of a particular accelerometer set, the more likely it will be
chosen to be mutated.
- Percent Crossover—This
is the percentage of the new generation that will be created by crossing
two members of the previous generation. Two accelerometer sets are randomly
selected based on the inverse of their cost. (Lower cost means they are
more likely to be selected.) The crossover process takes these two gene
sequences, A and B, and crosses them to simulate cross breeding. The result
of the crossover is one sequence that has some DOF from A and B, and another
sequence that has the complementary DOF of A and B.
- Mutation Control—As
discussed, the Mutation Control parameter controls the percentage
of mutated DOF in an accelerometer set.
Figure 15. Genetic Algorithm
options form
The sum of Percent Reproduction, Mutation, and Crossover
must sum to 100. Multiple rows can be added to the Generation Control
table to specify different generation parameters for a subset of the total
number of generations. The total number of generations is the sum over
the first column. To add a row enter the appropriate values in the text
boxes at the bottom of each column and click apply. To modify a row click
the row and modify the values in the text boxes and click apply. Then
remove the original row.