Calculation of the elevator round-trip time under destination group control using offline batch allocations and real-time allocations

The use of Destination Group Control (DGC), or Hall Call Allocation (HCA), in elevator traffic system group control is the current trend in intelligent and advanced supervisory control and expected to dominate the market in the future. In the conventional elevator traffic design process, designers usually start with a simple calculation in order to obtain a conceptual estimate of the suggested design prior to moving onto simulation. But due to the lack of a suitable set of equations for elevator traffic calculation for DGC systems, designers are forced to carry out the elevator traffic design process for a system controlled by DGC solely by using simulation. Due to dependence on the simulator and algorithms it uses, different simulation packages will produce different resultant designs. Thus, the motivation for this paper is to use calculation in order to achieve more transparency and repeatability in the design of DGC systems. In order to enable the designer to carry out a calculation for the DGC system, equations are needed to evaluate the values of H (the highest reversal floor) and S (the expected number of stops in a round trip) in order to evaluate the value of the round-trip time under destination group control. Although equations are available to compute the highest reversal floor, H, and expected number of stops, S, of a DGC system, these equations assume optimal idealized conditions and do not take into consideration the effect of real time allocation of landing calls to elevator cars. If designers use them to design the elevator traffic system, the design will be under-sized and inadequate. They do not take into consideration many of the practical implementation issues and non-ideal conditions such as: unequal floor populations, real time call allocation of calls to elevator cars, and the different floor to sector arrangements, as well as the practicalities of allocating elevator cars to sectors. In this paper, more detailed consideration is given to the estimation of H and S under both offline and real-time call allocations under up-peak traffic conditions. Three methods of sectoring are suggested to take care of different combinations of the number of floors, the number of elevators, the car capacity, and the floor population distribution. Results of this research would help the designer carry out a more reasonable and practical calculation of the round-trip time under DGC and thus arrive at a transparent and repeatable elevator traffic design. The designer is still expected to move on to a simulation phase in order to understand the effect of the group controller on system performance.