Energy-Efficient Routing of a Multirobot Station: A Flexible Time-Space Network Approach

This paper investigates a novel routing problem of a multi-robot station in a manufacturing cell. In the existing literature, the objective is to minimize the cycle time or energy consumption separately. The routing problem considered in this paper aims to reduce the cycle time and energy consumption jointly for each robot while avoiding...

Model Predictive Path Planning of AGVs: Mixed Logical Dynamical Formulation and Distributed Coordination

Most of the existing path planning methods of automated guided vehicles (AGVs) are static. This paper proposes a new methodology for the path planning of a fleet of AGVs to improve the flexibility, robustness, and scalability of the AGV system. We mathematically describe the transport process as a dynamical system using an ad hoc mixed...

Flexible time–space network formulation and hybrid metaheuristic for conflict-free and energy-efficient path planning of automated guided vehicles

Operations of Automated Guided Vehicles (AGVs) are desired to be more energy-efficient while maintaining high transport productivity, motivated by the green production requirements. This paper investigates a new energy-efficient planning problem for determining conflict-free paths of the AGVs in its transport roadmap. In this problem, the...

Mixed-Integer Nonlinear Programming for Energy-Efficient Container Handling: Formulation and Customized Genetic Algorithm

Energy consumption is expected to be reduced while maintaining high productivity for container handling. This paper investigates a new energy-efficient scheduling problem of automated container terminals, in which quay cranes (QCs) and lift automated guided vehicles (AGVs) cooperate to handle inbound and outbound containers. In our scheduling...

Robustness and stability of integrated stochastic optimization approaches for scheduling trains and railway infrastructure

This work addresses a tactical railway traffic management problem focused on the opti-mization of train dispatching decisions and timing decisions related to short-term main-tenance works in a railway network subject to disturbed process times. This is modeled as a mixed-integer programming formulation in which the traffic flow and track mainten...

Coordination of scheduling decisions in the management of airport airspace and taxiway operations

This paper addresses the real-time problem of coordinating aircraft ground and air operations in an airport area. At a congested airport, airborne decisions are related to take-off and landing operations, while ground (taxiway) decisions consist of scheduling aircraft movements between the gates and the runways. Since the runways are the...

Railway line capacity consumption of different railway signalling systems under scheduled and disturbed conditions

This paper evaluates the capacity consumption on a Dutch railway line both under scheduled and disturbed traffic conditions. For the scheduled condition the standard UIC compression method is used, while the computation of capacity consumption under disturbed conditions requires multiple simulation runs via a Monte Carlo simulation set up. For...

Rescheduling models for network-wide railway traffic management

In the last decades of railway operations research, microscopic models have been intensively studied to support traffic operators in managing their dispatching areas. However, those models result in long computation times for large and highly utilized networks. The problem of controlling country-wide traffic is still open since the coordination...

Optimal inter-area coordination of train rescheduling decisions

Railway dispatchers reschedule trains in real-time in order to limit the propagation of disturbances and to regulate traffic in their respective dispatching areas by minimizing the deviation from the off-line timetable. However, the decisions taken in one area may influence the quality and even the feasibility of train schedules in the other...

Centralized versus distributed systems to reschedule trains in two dispatching areas

Railway dispatchers are in charge of rescheduling trains during operations in order to limit propagation of disturbances occurring in real-time. To help the dispatchers in such task, an advanced decision support system, ROMA (Railway traffic Optimization by Means of Alternative graphs), has been recently implemented to optimize railway traffic...

Effectiveness of dynamic reordering and rerouting of trains in a complicated and densely occupied station area

Railway traffic experiences disturbances during operations while dispatchers need actions to restore feasibility and limit spreading of delays through the network. To help the dispatcher in such task, the dispatching support tool ROMA (Railway traffic Optimization by Means of Alternative graphs) has been designed and implemented. We report on...

An Advanced Real-Time Train Dispatching System for Minimizing the Propagation of Delays in a Dispatching Area Under Severe Disturbances

In highly utilized rail networks, as in the Netherlands, conflicts and subsequent train delays propagate considerably in time and space during operations. In order to realistically forecast and minimize delay propagation, there is a need to extend short-term traffic planning up to several hours. On the other hand, as the magnitude of the time...

Improving real-time train dispatching: Models, algorithms and applications

Traffic controllers monitor railway traffic sequencing train movements and setting routes with the aim of ensuring smooth train behaviour and limiting as much as existing delays. Due to the strict time limit available for computing a new timetable during operations, which so far is rather infeasible by using existing tools, railway traffic...

The effectiveness of static implications in real-time railway traffic management

We study a real-time railway traffic management problem. It consists in adjusting train timetables in order to restore feasibility when unforeseen events in the network make unfeasible the off-line generated timetable. The problem can be formulated as a huge job-shop problem with blocking constraints, which has to be solved within strict time...