Enhancements to the Ground Processing Scheduling System

This paper describes work in progress to enhance the performance of the Ground Processing Scheduling System (GPSS). The GPSS is a constraint-based scheduler that deals with three kinds of constraints: temporal, resource, and configuration. It starts with a complete schedule that may have some constraint violations (conflicts) and gradually improves the schedule by reducing the violations. The objective is to optimize the schedule in terms of constraint violations and resource utilization. The enhancement is accomplished by improving heuristics currently used for constraint satisfaction and adding an extra feature which we call fencing. Fencing allows for obtaining a conflict-free sub-schedule within a selected period of time.