A review of design and control of automated guided vehicle systems <s> Bidirectional guide-path system <s> Most current applications of automated guided vehicle systems (AGVS) in manufacturing shop environments employ uni-directional guide-paths for vehicle routing despite the fact that bi-directional vehicles exist. In this paper comparisons and issues regarding unidirectional and bi-directional flows are presented. Also presented is a model of a bi-directional traffic flow guide-path. The effect of the traffic flow pattern on the shop throughput is demonstrated and compared to that of a uni-directional flow system of an equivalent facility. The model is implemented using computer simulation. <s> BIB001 </s> A review of design and control of automated guided vehicle systems <s> Bidirectional guide-path system <s> Recent technological development in vehicle design allow vehicles to operate without physical guide paths, i.e. free-ranging automated guided vehicles. This paper addresses the problem of defining flow paths for these vehicles. A model is presented whereby the number of allowable flow paths and the flow directions between nodes (representing pickup/delivery stations and aisle intersections) of the layout network are determined. Examples are presented to demonstrate the approach. <s> BIB002
The conventional bidirectional guide-path is not popular in material handling systems, although it can result in a higher productivity than the corresponding unidirectional guidepath system. The main reason is that the control problem in such systems becomes very complicated. This problem can be resolved by using dual unidirectional lanes. However, the dual lanes system needs more space and is more costly. In literature, there are only few studies on the conventional bidirectional guide-path system BIB001 BIB002 . BIB001 provide a guideline for design of singlelane bidirectional guide-path systems. BIB002 propose a model for a bidirectional guide-path system in which the travel distance and the number of lanes are minimized. The number and direction of lanes are decided in their model. The capacity of each lane and the maximum number of parallel lanes are given and fixed. Bidirectional guide-path systems are particularly used in systems where vehicle interference rarely happens rarely such as in tandem guide-path systems (section 2.4).