On-line planning and scheduling: an application to controlling modular printers

We present a case study of artificial intelligence techniques applied to the control of production printing equipment. Like many other real-world applications, this complex domain requires high-speed autonomous decision-making and robust continual operation. To our knowledge, this work represents the first successful industrial application of embedded domain-independent temporal planning. Our system handles execution failures and multi-objective preferences. At its heart is an on-line algorithm that combines techniques from state-space planning and partial-order scheduling. We suggest that this general architecture may prove useful in other applications as more intelligent systems operate in continual, on-line settings. Our system has been used to drive several commercial prototypes and has enabled a new product architecture for our industrial partner. When compared with state-of-the-art off-line planners, our system is hundreds of times faster and often finds better plans. Our experience demonstrates that domain-independent AI planning based on heuristic search can flexibly handle time, resources, replanning, and multiple objectives in a high-speed practical application without requiring hand-coded control knowledge

Optimising Flexibility of Temporal Problems with Uncertainty

Temporal networks have been applied in many autonomous systems. In real situations, we cannot ignore the uncertain factors when using those autonomous systems. Achieving robust schedules and temporal plans by optimising flexibility to tackle the uncertainty is the motivation of the thesis. This thesis focuses on the optimisation problems of temporal networks with uncertainty and controllable options in the field of Artificial Intelligence Planning and Scheduling. The goal of this thesis is to construct flexibility and robustness metrics for temporal networks under the constraints of different levels of controllability. Furthermore, optimising flexibility for temporal plans and schedules to achieve robust solutions with flexible executions. When solving temporal problems with uncertainty, postponing decisions according to the observations of uncertain events enables flexible strategies as the solutions instead of fixed schedules or plans. Among the three levels of controllability of the Simple Temporal Problem with Uncertainty (STPU), a problem is dynamically controllable if there is a successful dynamic strategy such that every decision in it is made according to the observations of past events. In the thesis, we make the following contributions. (1) We introduce an optimisation model for STPU based on the existing dynamic controllability checking algorithms. Some flexibility and robustness measures are introduced based on the model. (2) We extend the definition and verification algorithm of dynamic controllability to temporal problems with controllable discrete variables and uncertainty, which is called Controllable Conditional Temporal Problems with Uncertainty (CCTPU). An entirely dynamically controllable strategy of CCTPU consists of both temporal scheduling and variable assignments being dynamically decided, which maximize the flexibility of the execution. (3) We introduce optimisation models of CCTPU under fully dynamic controllability. The optimisation models aim to answer the questions how flexible, robust or controllable a schedule or temporal plan is. The experiments show that making decisions dynamically can achieve better objective values than doing statically. The thesis also contributes to the field of AI planning and scheduling by introducing robustness metrics of temporal networks, proposing an envelope-based algorithm that can check dynamic controllability of temporal networks with uncertainty and controllable discrete decisions, evaluating improvements from making decisions strongly controllable to temporally dynamically controllable and fully dynamically controllable and comparing the runtime of different implementations to present the scalability of dynamically controllable strategies

Search Strategies for Scheduling Problems

V předložené práci porovnávám prohledávací strategie pro řešení rozvrhovacích problémů z pohledu programování s omezujícími podmínkami. Těžiště práce je věnováno rozvrhovacím problémům obsahujícím alternativní úlohy. V práci jsou jednak rozebrány různé již publikované způsoby modelování těchto problémů, dále pak jsou popsány a experimentálně porovnány prohledávací strategie pracující s těmito modely. Porovnáván je zejména vliv strategií na rychlost práce řešiče v závislosti na typu a velikosti dat. Jako vedlejší efekt práce studuje možnosti řešení rozvrhovacích problémů obsahujících alternativní úlohy pomocí řešiče Choco, který byl pro implementaci experimentů použit.In the present work I compare the search strategies for solving scheduling problems from the view of constraint programming. The thesis is focused on scheduling problems containing alternative activities. An analysis of previously published various ways of modelling the problems is provided, next description and experimental comparison of search strategies targetting these models is provided. The influence of strategies on the speed of the solver is studied primarily. As a sideeffect the work studies the ways how Choco solver, which was utililized for implementation of the experiments, can be used to solve the scheduling problems with alternative activities.Department of Theoretical Computer Science and Mathematical LogicKatedra teoretické informatiky a matematické logikyFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Global Constraint Catalog, 2nd Edition (revision a)

This report presents a catalogue of global constraints where each constraint is explicitly described in terms of graph properties and/or automata and/or first order logical formulae with arithmetic. When available, it also presents some typical usage as well as some pointers to existing filtering algorithms

Applications of network optimization

Includes bibliographical references (p. 41-48).Ravindra K. Ahuja ... [et al.]

Global Constraint Catalog, 2nd Edition

This report presents a catalogue of global constraints where each constraint is explicitly described in terms of graph properties and/or automata and/or first order logical formulae with arithmetic. When available, it also presents some typical usage as well as some pointers to existing filtering algorithms

Strategic Employee Scheduling

Abstract. Today's highly competitive economy calls for new methods of management. Advanced practices have been proposed to manage human resources, often acclaimed to be the most important assets of any organisation. However, computer models and applications to support these methods are often not available, or not until it is much too late. This paper presents several directions for advances in strategic employee scheduling, as well as our approach for implementing these concepts

Robustness for a single railway line: Analytical and simulation methods

[EN] Railway scheduling has been a significant issue in the railway industry. Over the last few years, numerous approaches and tools have been developed to compute railway scheduling. However, robust solutions are necessary to absorb short disruptions. In this paper, we present the robustness problem from the point of view of railway operators and we propose analytical and simulation methods to measure robustness in a single railway line. In the analytical approach, we have developed some formulas to measure robustness based on the study of railway line infrastructure topology and buffer times. In the simulation approach, we have developed a software tool to assess the robustness for a given schedule. These methods have been inserted in MOM (More information can be found at the MOM web page http://www.dsic.upv.es/users/ia/gps/MOM), which is a project in collaboration with the Spanish Railway Infrastructure Manager (ADIF). © 2012 Elsevier Ltd. All rights reserved.This work has been partially supported by the research project TIN2010-20976-C02-01 (Min. de Economia y Competitividad, Spain) and project PIRSES-GA-2011-294931 (FP7-PEOPLE-2011-IRSES).Salido Gregorio, MA.; Barber Sanchís, F.; Ingolotti Hetter, LP. (2012). Robustness for a single railway line: Analytical and simulation methods. Expert Systems with Applications. 39(18):13305-13327. https://doi.org/10.1016/j.eswa.2012.05.071S1330513327391