A Two-Stage Path Planning Method for the Rearrangement Problem in Modular Puzzle-Based Storage System
Table 2
Additional notation.
Symbol
Definition
A = [source(A), direction(A)]
A single move, where source(A) denotes the source slot to be moved and direction(A) denotes the moving direction. For an internal move, direction(A) = 1 or -1, which means clockwise or anticlockwise, respectively; for an exchange move, direction(A) = 2 or -2, which means moving-in or moving-out, respectively.
slot(s)
The slot index of item
= {Ak}
A sequence of single moves, where Ak is a single move.
A single move plan of the module.
previous(i)
The previous (anticlockwise adjacent) slot index of slot i.
next(i)
The next (clockwise adjacent) slot index of slot i.
matched(i)
Slot index in corresponding to slot i in .
between(i1, i2)
A set of items between slot i1 and slot i2 in a current state
d= [type(d), distance(d)]
An exchange demand generated by the picking module, where type(d) denotes the type of required item, and distance(d) denotes the remaining steps for exchange move of d.
D = {d}
A set of exchange demands generated by the picking module.