Gantry Scheduling for Multi-Gantry Production System by Online Task Allocation Method

Abstract

For a multi-gantry production system, in which several gantries move among the machines and load/unload parts, the assignment of gantries directly impacts the system performance. Gantry scheduling problem is extremely important, involving when and where the gantries are assigned to the machines. This letter formulates the gantry scheduling problem as an online task allocation (OTA) problem, and solves for an optimal gantry assignment policy to maximize the system throughput. The multi-gantry production system is analyzed and important system properties are derived. The production system performance is evaluated through permanent production loss and opportunity window. Such knowledge is used to define the key parameters in the OTA problem. Based on the analysis of the system production performance, the optimization problem is solved and consequently a gantry assignment policy is proposed. A numerical study is performed to demonstrate the effectiveness of the proposed policy by comparing with first-come-first-served policy.