A review of design and control of automated guided vehicle systems <s> Dynamic vehicle positioning strategy <s> It is discussed how to determine the home location of idle vehicles in an automated guided vehicles (AGVs) with a loop guidepath to minimize the mean response time for a pickup call. Static positioning strategy is analyzed in which a single-parking space is allocated for all the idle vehicles. And dynamic positioning strategy is also considered where a new positioning location is assigned whenever a vehicle becomes idle. Both the cases of unidirectional and bidirectional guidepath are considered. We provide a numerical example to illustrate the algorithm developed for each case. <s> BIB001 </s> A review of design and control of automated guided vehicle systems <s> Dynamic vehicle positioning strategy <s> One of the control decisions in the operation of an automated guided vehicle (AGV) system is to determine the home locations of idle vehicles. In this paper, the problems of selecting home location of a vehicle when idle in a single loop AGV network is presented. As the number of unit loads to be picked up at each workstation dynamically changes over time, the optimum home location of vehicles may also change. Based on the objective of minimizing the expected response time of a vehicle, models are constructed. Example problems are given to illustrate the use of the solution algorithms. The results of the system response times obtained using the dynamic dwell point models are compared with those of other dwell point rules. <s> BIB002 </s> A review of design and control of automated guided vehicle systems <s> Dynamic vehicle positioning strategy <s> In the study of automated guided vehicles systems (AGVS), one assumption often made in the management of vehicles is the existence of either home locations or a circulatory loop to buffer or hold idle vehicles. A review of AGVS literature reveals that different researchers pursue one idle vehicle management policy or the other. In some studies, idle vehicles are assumed to circulate in some loops in the system while others assume they are routed to some dwell point locations where they are held until they are reassigned. When the dwell point option is implemented, different strategies for implementation are also available. However, what is generally lacking in references to dwell point strategies are the techniques for selecting the optimal or best dwell points for a given facility. In this study, the problem of dwell point or home location specification is addressed. The problem was modelled mathematically to determine the optimal home locations. The emphasis in the paper is on a unidirectional AGVS guid... <s> BIB003
When pick up demands at the stations change over time, the home locations of vehicles may need to be changed. In order to adapt to this situation some dynamic procedures for selecting dwell points are proposed. BIB001 adapts his static algorithms to cope with the dynamic situation. Kim's algorithm bases on the calculation of the contribution of each segment on the circular layout to the mean angular travel distance. BIB002 propose dynamic algorithms to select the home location of a single vehicle in the unidirectional and bidirectional loop. They show that, in a very busy system, the performance is independent of the dwell point selection rules. BIB003 extend their algorithms to the situation where the pick-up demands change over time in a non-uniform manner. Their method requires an accurate update of load pick-ups remaining at each station at event times. When the ratio of remaining load pick-ups changes, the idle-vehicle positioning problem has to be solved again. Their algorithm applies for minimizing both the maximum response time and the mean response time. Most studies in this area concentrate on loop layouts only. The research by BIB003 is the only one that takes conventional layouts into account. In practice, companies may define fixed parking locations, because vehicles may or can only park in certain areas. These areas can be defined for safety reasons, to avoid congestion, to allow a change of drivers, to recharge the vehicle's battery, etc. and impose constraints on the idle vehicle positioning problem. Such practical issues are often overlooked or omitted in theoretical models of automated material handling systems.