INTELLIGENT CONTROL OF MATERIAL HANDLING SYSTEMS - Environmentally Conscious Materials Handling - page 109

U i U i U i + 1 U i + 1 U i + 2 U i + 2

F g F g

F s , i, 2 F s , i, 2

q j , 1 q j , 1

q i , 2 q i , 2

q i , 1 q i , 1

F g F g

d i , [1-2] d i , [1-2]

F s , i, 3 F s , i, 3

q i , 3 q i , 3

Figure 3.29 Parent validation problem

In the example, agent q i, 3 would move upward in time due to gravitation and
the position of q i, 2 , but it is rather obvious to see that q i, 2 is not very reliable
due to position of q i, 1 that seems to have settled next to q i, 1 . It is not certain that
the parent validation will improve the plan of the system, but it is introduced to
dampen oscillations of agents. One way to validate the parent is to look at its
position according to its parent, as illustrated by the dimension in Figure 3.29.
Figure 3.30 shows the result of a scenario with 25 bars both with and without
the parent validation. As expected, the plan becomes more stable with the parent
validation, but it also has a longer settling time as a natural consequence.

13.3 Floating

The last improvement is called floating agents , and is best described from
Figure 3.31.
According to Figure 3.31, an agent q i would behave as in the left case (a).
The action field of an agent only allows an agent to move in the direction of the
resulting force until it is blocked by other agents, in this case q j , even though the
force is larger. By extending the action field to the size of the resulting force and
allow the agent to float over another agent q j many conflicts might be avoided.
It is similar to allow the agent to search for a valid position from the bottom
of its action field, as illustrated in the right case (b), whereas the agent in (a)
searches from the top until it meets a block or the end of the force vector.
Figure 3.32 presents the results of the scenario with and without the floating
improvement enabled. There might be more fluctuations with floating enabled,
but as expected, it dramatically improves not only the settling time but also the
overall satisfaction level, as the agents avoid many conflict caused by tensions
between agents.