Energy-efficient Rail Guided Vehicle Routing for Two-Sided Loading/Unloading Automated Freight Handling System

摘要

Rail-guided vehicles (RGVs) are widely employed in automated freight handlingsystem (AFHS) to transport surging air cargo. Energy-efficient routing of suchvehicles is of great interest for both financial and environmentalsustainability. Given a multi-capacity RGV working on a linear track in AFHS,we consider its optimal routing under two-sided loading/unloading (TSLU)operations, in which energy consumption is minimized under conflict-avoidanceand time window constraints. The energy consumption takes account ofrouting-dependent gross weight and dynamics of the RGV, and theconflict-avoidance constraints ensure conflict-free transport service underTSLU operations. The problem is formulated as a mixed-integer linear program,and solved by incorporating valid inequalities that exploit structuralproperties of the problem. The static problem model and solution approach arethen integrated with a rolling-horizon approach to solve the dynamic routingproblem where air cargo enters and departs from the system dynamically in time.Simulation results suggest that the proposed strategy is able to route an RGVto transport air cargo with an energy cost that is considerably lower than oneof the most commonly used heuristic methods implemented in current practice.