Towards the design of optimal range assignment for elevator groups under fluctuant traffic loads

With the development of embedded devices, elevator group systems that manage elevators can be designed in an intelligent way. In the design of elevator group systems, one of the most important problems is to determine the 'range assignment' for each elevator, which indicates the floors that an elevator will serve. In reality, the traffic loads of a building are different in terms of time periods, called fluctuant traffic loads, which makes the above problem much more challenging. The objective of this paper is to determine the optimal range assignment that can maximize the number of passengers served in a certain amount of time. The elevator group system can adapt to varying traffic loads and achieve fault tolerance by conducting range reassignment. In this paper, we build a Mixed Integer Linear Programming (MILP) to find the optimal range assignment. However, MILP suffers from large computational complexities and it is impractical since the elevator group system needs to response to fluctuant traffic loads in real-time. Therefore, we devise efficient algorithms to obtain near optimal solutions. Experimental results show that we can achieve 48% and 25% improvements on average in the completion time and the average waiting time, respectively.