INTELLIGENT CONTROL OF MATERIAL HANDLING SYSTEMS - Environmentally Conscious Materials Handling - page 90

diverter should be concerned about the relevancy of reconsidering the route
for a tote, because in many cases there is only one possible direction at a
given diverter for a given tote.
So the decision logic, rather, is identical to the dynamic routing principle
of toploaders, but diverters should fine-tune their decisions according to
the local environment in which they are situated. In other words, a strong
influence on the decision logic of the diverter is based on its position in
the routing graph.
Similar to the toploader, the principal tasks of the diverter can be illus-
trated by a state diagram, shown in Figure 3.15.

• Mergers . Mergers are the opposite of diverters, as they merge two lanes.
Traditionally, mergers are not controlled, as there are no alternatives to
continuing on the single lane ahead, and the merger simply alters between
taking one tote from either input lane, if both are occupied.
Obviously, more intelligent decisions could be considered than just
switching between the input lanes, which is the argument for applying
agents to the merger elements. The ratio between merging totes from the
input lanes should be determined by the aggregated data of the totes in
either of the two lanes (e.g., if the number of urgent totes waiting to be
merged is higher in one lane, then that lane should be given higher pri-
ority). Also waiting totes in one lane could have greater impact on the
overall system performance, if a queue of totes in one lane is more likely
to block other routes behind that point.

Discharge
agent

Discharge
agent

Discharge
agent

contract net

Locating
dests

Dests
found

Tote at
diverter

arriving
tote

Idle

Determining
route

Diverting
tote

Route
agent

Figure 3.15 Principal tasks of a diverter