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Task Roadmaps: Speeding up Task Replanning
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. ABB AB, Vasteras, Sweden.
ABB AB, Västerås, Sweden..
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0002-1364-8127
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0001-6132-7945
2022 (English)In: Frontiers in Robotics and AI, E-ISSN 2296-9144, Vol. 9Article in journal (Refereed) Published
Abstract [en]

Modern industrial robots are increasingly deployed in dynamic environments, where unpredictable events are expected to impact the robot's operation. Under these conditions, runtime task replanning is required to avoid failures and unnecessary stops, while keeping up productivity. Task replanning is a long-sighted complement to path replanning, which is mostly concerned with avoiding unexpected obstacles that can lead to potentially unsafe situations. This paper focuses on task replanning as a way to dynamically adjust the robot behaviour to the continuously evolving environment in which it is deployed. Analogously to probabilistic roadmaps used in path planning, we propose the concept of Task roadmaps as a method to replan tasks by leveraging an offline generated search space. A graph-based model of the robot application is converted to a task scheduling problem to be solved by a proposed Branch and Bound (B&B) approach and two benchmark approaches: Mixed Integer Linear Programming (MILP) and Planning Domain Definition Language (PDDL). The B&B approach is proposed to compute the task roadmap, which is then reused to replan for unforeseeable events. The optimality and efficiency of this replanning approach are demonstrated in a simulation-based experiment with a mobile manipulator in a kitting application. In this study, the proposed B&B Task Roadmap replanning approach is significantly faster than a MILP solver and a PDDL based planner. 

Place, publisher, year, edition, pages
2022. Vol. 9
Keywords [en]
ROS; autonomous robots; optimization; robot task modelling; task planning.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-58282DOI: 10.3389/frobt.2022.816355ISI: 000795890300001Scopus ID: 2-s2.0-85130221719OAI: oai:DiVA.org:mdh-58282DiVA, id: diva2:1660574
Funder
Swedish Foundation for Strategic ResearchAvailable from: 2022-05-24 Created: 2022-05-24 Last updated: 2025-10-10Bibliographically approved
In thesis
1. Task Planning of Industrial Mobile Robots in Collaborative Dynamic Environments
Open this publication in new window or tab >>Task Planning of Industrial Mobile Robots in Collaborative Dynamic Environments
2025 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Over the past decades, industrial robotics has transitioned from fixed, single-purpose machines to flexible, collaborative mobile systems capable of navigating complex factory environments. Today's manufacturing demands, driven by labor scarcity, the need for rapid reconfiguration, and advances in AI and sensing, require robots to perform increasingly sophisticated, non-repetitive tasks alongside human workers. Designing and executing efficient multi-robot missions in such dynamic, human-in-the-loop settings presents multiple challenges: expressing high-level production requirements in a planner-friendly way, handling unexpected execution errors, scaling to large task allocations, and accounting for uncertainties in task durations and human behavior.

This thesis introduces an intuitive task modeling formalism and a suite of algorithmic methods that address these challenges end-to-end. First, we propose a domain-expert-friendly syntax for defining single-robot production missions, automatically generating problem definitions compatible with diverse off-the-shelf planners. To support rapid recovery from errors, we present task roadmaps, a novel planning algorithm that reuses the original search tree to accelerate replanning when execution deviates. We extend the formalism to a multi-robot kitting use case with alternative task locations and introduce a scalable, clustering-based approach to maintain computational tractability.

Recognizing the inherent uncertainties of human-robot collaboration, we further develop a collaborative stochastic task planning framework that integrates human risk preferences and models variability in task and routing durations. Finally, we tackle a collaborative production scenario with complex cross-schedule dependencies, proposing a stochastic scheduling method that generates optimized, deadlock-free plans while balancing efficiency with human well-being.

Extensive simulations and experiments grounded in real-world applications demonstrate that our methods significantly improve planning efficiency, robustness, and adaptability in dynamic industrial settings, paving the way toward more resilient, human-centric robotic automation.

Abstract [sv]

Under de senaste decennierna har industrirobotiken utvecklats från stationära maskiner specialiserade för enstaka typer av uppgifter till flexibla, kollaborativa och mobila system som kan navigera i komplexa fabriksmiljöer. Dagens tillverkningskrav, drivna av bristen på arbetskraft, behovet av snabba omställningar samt framsteg inom AI och sensorteknik, fordrar att robotar utför alltmer sofistikerade, icke-repetitiva uppgifter tillsammans med mänsklig arbetskraft. Att effektivt utforma och genomföra produktionsuppdrag som omfattar samarbete mellan robotar och människor i den typen av dynamiska miljöer medför flera utmaningar: att specificera produktionsprocessen på en användarvänlig abstraktionsnivå som underlättar resursplaneringen,att hantera oväntade fel under exekvering, att skala upp antalet arbetsmoment som ska fördelas och att hantera osäkerheter i tidsåtgång och mänskligt beteende.

Denna avhandling introducerar ett intuitivt sätt att definiera och organisera arbetsmomentsamt en uppsättning algoritmiska metoder som hanterar utmaningarna genom hela kedjan.Först föreslår vi en användarvänlig modellering för att definiera produktionsuppdrag för en robot, med automatisk generering av planeringsproblem kompatibla med olika kommersiella planeringsverktyg. För att möjliggöra en snabb återhämtning vid fel under drift presenterar vi task roadmaps, en ny planeringsalgoritm som återanvänder det ursprungliga sökträdet för att accelerera en omplanering  när exekveringen avviker. Vi utökar modelleringen till en multi-robot kitting-applikation med alternativa upphämtningsplatser och introducerar en klustringsbaserad algoritm som är beräkningsmässigt hanterbar för uppskalade problem.

Med hänsyn till de inneboende osäkerheterna i människa–robot-samarbete utvecklar vi dessutom ett kollaborativt stokastiskt ramverk för planering av robot-uppgifter som integrerar mänskliga riskpreferenser och modellerar en varierande tidsåtgång för arbetsmoment och förflyttningar. Slutligen behandlar vi ett kollaborativt produktionsscenario med komplexa korsschemaberoenden och föreslår en stokastisk schemaläggningsmetod som genererar optimerade, låsningsfria planer där effektivitet balanseras med mänskligt välbefinnande.

Omfattande simuleringar och experiment baserade på realistiska applikationer visar att våra metoder väsentligen förbättrar effektivitet, robusthet och anpassningsbarhet av robot-planering i dynamiska industriella miljöer, vilket banar väg för en mer hållbar, människocentrerad robotautomatisering.

Place, publisher, year, edition, pages
Västerås: Mälardalens universitet, 2025
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 441
National Category
Robotics and automation
Research subject
Computer Science
Identifiers
urn:nbn:se:mdh:diva-73159 (URN)978-91-7485-721-4 (ISBN)
Public defence
2025-10-24, My och digitalt, Mälardalens universitet, Västerås, 09:15 (English)
Opponent
Supervisors
Available from: 2025-09-02 Created: 2025-09-02 Last updated: 2025-10-10Bibliographically approved

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Lager, AndersSpampinato, GiacomoPapadopoulos, AlessandroNolte, Thomas

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