Mathematical Modelling and Methods for Load Balancing and Coordination of Multi-Robot Stations

The automotive industry is moving from mass production towards an individualized production, individualizing parts aims to improve product quality and to reduce costs and material waste. This thesis concerns aspects of load balancing and coordination of multi-robot stations in the automotive manufacturing industry, considering efficient algorithms required by an individualized production. The goal of the load balancing problem is to improve the equipment utilization. Several approaches for solving the load balancing problem are suggested along with details on mathematical tools and subroutines employed.Our contributions to the solution of the load balancing problem are fourfold. First, to circumvent robot coordination we construct disjoint robot programs, which require no coordination schemes, are flexible, admit competitive cycle times for several industrial instances, and may be preferred in an individualized production. Second, since solving the task assignment problem for generating the disjoint robot programs was found to be unreasonably time-consuming, we model it as a generalized unrelated parallel machine problem with set packing constraints and suggest a tailored Lagrangian-based branch-and-bound algorithm. Third, a continuous collision detection method needs to determine whether the sweeps of multiple moving robots are disjoint. We suggest using the maximum velocity of each robot along with distance computations at certain robot configurations to derive a function that provides lower bounds on the minimum distance between the sweeps. The lower bounding function is iteratively minimized and updated with new distance information; our method is substantially faster than previously developed methods. Fourth, to allow for load balancing of complex multi-robot stations we generalize the disjoint robot programs into sequences of such; for some instances this procedure provides a significant equipment utilization improvement in comparison with previous automated methods

A Conceptual Design of an Integrated Façade System to Reduce Embodied Energy in Residential Buildings

(1) The overall energy requirement of a building may be impacted by the building design, the selection of materials, the construction methods, and lifecycle management. To achieve an optimum energy-efficiency level when dealing with a new building or renovation project, it is important to improve the entire construction process as it is not enough to merely focus on the operational phase. If conventional construction practices do not evolve, compromise, or adapt to necessary changes, then it becomes challenging to deliver an ultimate low energy building. (2) This paper demonstrates the trend of off-site prefabrication and its production principles and the notions of open-building design and Design for X, as well as offering an overview of the development of automation in construction, which provides both insights and evaluations based on the context of the research. (3) Three European Union Horizon 2020 research projects were evaluated, and the outcome of the projects served as the backbone for the research and inspired the design of the proposed integrated façade system. Two design scenarios were proposed to demonstrate the potential improvements that could be achieved in a new build as well as in renovation projects. (4) The research lays a foundation for establishing a larger cross-disciplinary collaboration in the future.This research was funded by ZERO-PLUS, from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 678407. The authors would like to thank to following research projects: BERTIM received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 636984. HEPHAESTUS received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 732513

Mathematical Modelling for Load Balancing and Minimization of Coordination Losses in Multirobot Stations

The automotive industry is moving from mass production towards an individualized production, in order to improve product quality and reduce costs and material waste. This thesis concerns aspects of load balancing of industrial robots in the automotive manufacturing industry, considering efficient algorithms required by an individualized production. The goal of the load balancing problem is to improve the equipment utilization. Several approaches for solving the load balancing problem are presented along with details on mathematical tools and subroutines employed.Our contributions to the solution of the load balancing problem are manifold. First, to circumvent robot coordination we have constructed disjoint robot programs, which require no coordination schemes, are more flexible, admit competitive cycle times for some industrial instances, and may be preferred in an individualized production. Second, since solving the task assignment problem for generating the disjoint robot programs was found to be unreasonably time-consuming, we modelled it as a generalized unrelated parallel machine problem with set packing constraints and suggested a tighter model formulation, which was proven to be much more tractable for a branch--and--cut solver. Third, within continuous collision detection it needs to be determined whether the sweeps of multiple moving robots are disjoint. Our solution uses the maximum velocity of each robot along with distance computations at certain robot configurations to derive a function that provides lower bounds on the minimum distance between the sweeps. The lower bounding function is iteratively minimized and updated with new distance information; our method is substantially faster than previously developed methods

Multiple Robot Boundary Tracking with Phase and Workload Balancing

This thesis discusses the use of a cooperative multiple robot system as applied to distributed tracking and sampling of a boundary edge. Within this system the boundary edge is partitioned into subsegments, each allocated to a particular robot such that workload is balanced across the robots. Also, to minimize the time between sampling local areas of the boundary edge, it is desirable to minimize the difference between each robot’s progression (i.e. phase) along its allocated sub segment of the edge. The paper introduces a new distributed controller that handles both workload and phase balancing. Simulation results are used to illustrate the effectiveness of the controller in an Autonomous Underwater Vehicle (AUV) under ice edge sampling application. Successful results from experimentation with three iRobot(R) Creates are also presented

A Tutorial on Distributed Optimization for Cooperative Robotics: from Setups and Algorithms to Toolboxes and Research Directions

Several interesting problems in multi-robot systems can be cast in the framework of distributed optimization. Examples include multi-robot task allocation, vehicle routing, target protection and surveillance. While the theoretical analysis of distributed optimization algorithms has received significant attention, its application to cooperative robotics has not been investigated in detail. In this paper, we show how notable scenarios in cooperative robotics can be addressed by suitable distributed optimization setups. Specifically, after a brief introduction on the widely investigated consensus optimization (most suited for data analytics) and on the partition-based setup (matching the graph structure in the optimization), we focus on two distributed settings modeling several scenarios in cooperative robotics, i.e., the so-called constraint-coupled and aggregative optimization frameworks. For each one, we consider use-case applications, and we discuss tailored distributed algorithms with their convergence properties. Then, we revise state-of-the-art toolboxes allowing for the implementation of distributed schemes on real networks of robots without central coordinators. For each use case, we discuss their implementation in these toolboxes and provide simulations and real experiments on networks of heterogeneous robots

Intralogistics fleet management system for highly secure areas

With the end of traditional centralized applications for production control, a new industrial era (industry 4.0) introduces computational concepts and a vision of cyberphysical ecosystems associated with intelligent factories. Using automation technologies adopts the combination of the physical and the cyber world’s, to make the technologies involved more complex and precise [48].With the search for better resource use, time, cost, and quality has been introducing by the industry, new technological challenges as work agents, instead of the traditional man labor. Which has been replaced by autonomous robotic mechanisms. Many entities choose autonomous mobile units to fulfill the dispatching tasks and the supply of material to workstations. Thus, it is necessary to have a system capable of managing all activities and behaviors adjacent to these autonomous mobile robots. The objective of this dissertation is the implementation of a management system for a fleet of mobile robots that perform logistics processes in a secure environment. The robots will move between the production and expedition areas and autonomously carry out the loading and unloading of goods between workstations. Sharing spaces and resources among themselves and with factory operators, such as stations, corridors, security doors, and elevators. The proposed model explores the scheduling of tasks to robots as their monitoring and security in all processes, from autonomous navigation to area’s transition of areas by the present security devices. The presence of several sets of sensors and devices in these units is essential to provide sensorial information about the manufacturing environment and at the same time assisting in the execution of the tasks, such as navigation, transport, loading. To extract all the functionalities, this system will also be integrated with the management and security systems of the factory, to create an overview of the current state of the shop-floor and to plan accordingly. They are integrated to provide secure communication, based on reliable protocols that ensure the veracity and communication of the entities.Com o fim das tradicionais aplicações centralizadas para controle de produção a chegada de uma nova era industrial (indústria 4.0), introduz conceitos computacionais e uma visão de ecossistemas de ciber-fisicos associados a fábricas inteligentes. Utilizando tecnologias de automação, adota a combinação do mundo físico e do mundo cibernético, para tornar as tecnologias envolvidas mais complexas e precisas [48]. Com a procura de um melhor aproveitamento de recursos, de tempo, custo e qualidade por parte da indústria, esta tem vindo a introduzir novos desafios tecnológicos como ferramentas de trabalho, ao invés da tradicional mão de obra realizada pelo homem. Que tem vindo a ser substituída por mecanismos autônomos robotizados. Muitas entidades optam por unidades autônomas móveis para o cumprimento das tarefas de despacho e de fornecimento de material às estações de trabalho. Desta forma é necessário um sistema capaz de gerir todas as atividades e comportamentos adjacentes a estes robôs moveis autônomos. O objetivo desta dissertação é a implementação de um sistema de gestão para uma frota de robots movéis que realizam processos de logística em fábricas de segurança. Os robots transitarão entre as áreas de produção e áreas de expedição para realizar autonomamente processos de carga e descarga de mercadorias nas estações de trabalho. Compartilhando entre si e com os operadores da fábrica espaços e recursos, como estações, corredores, portas de segurança e elevadores. O modelo proposto explora o agendamento de tarefas aos robots como respetiva monitorização e segurança, em todos os processos desde navegação autónoma até á transição de espaços usando as estruturas de segurança presentes. Para que exista uma comunicação entre um sistema de gestão da frota e as unidades móveis é essencial a presença de vários conjuntos de sensores e dispositivos nestas unidades, para que estes estejam aptas a fornecer informação sensorial sobre ambiente fabril e ao mesmo tempo no auxiliar na execução de tarefas, como navegação, transporte etc. A fim de extrair todas as funcionalidades este sistema será também integrado com os sistemas de gestão e de segurança da fábrica, de forma a criar uma visão geral do estado atual da fábrica e planejar adequadamente. São integrados conjuntamente para fornecer uma comunicação segura, com base em protocolos entre as entidades

A Lightweight Modular Continuum Manipulator with IMU-based Force Estimation

Most aerial manipulators use serial rigid-link designs, which results in large forces when initiating contacts during manipulation and could cause flight stability difficulty. This limitation could potentially be improved by the compliance of continuum manipulators. To achieve this goal, we present the novel design of a compact, lightweight, and modular cable-driven continuum manipulator for aerial drones. We then derive a complete modeling framework for its kinematics, statics, and stiffness (compliance). The modeling framework can guide the control and design problems to integrate the manipulator to aerial drones. In addition, thanks to the derived stiffness (compliance) matrix, and using a low-cost IMU sensor to capture deformation angles, we present a simple method to estimate manipulation force at the tip of the manipulator. We report preliminary experimental validations of the hardware prototype, providing insights on its manipulation feasibility. We also report preliminary results of the IMU-based force estimation method.Comment: 12 pages, submitted to ASME Journal of Mechanisms and Robotics 2022, under review. arXiv admin note: substantial text overlap with arXiv:2206.0624

An Iterative Approach for Collision Feee Routing and Scheduling in Multirobot Stations

This work is inspired by the problem of planning sequences of operations, as welding, in car manufacturing stations where multiple industrial robots cooperate. The goal is to minimize the station cycle time, \emph{i.e.} the time it takes for the last robot to finish its cycle. This is done by dispatching the tasks among the robots, and by routing and scheduling the robots in a collision-free way, such that they perform all predefined tasks. We propose an iterative and decoupled approach in order to cope with the high complexity of the problem. First, collisions among robots are neglected, leading to a min-max Multiple Generalized Traveling Salesman Problem (MGTSP). Then, when the sets of robot loads have been obtained and fixed, we sequence and schedule their tasks, with the aim to avoid conflicts. The first problem (min-max MGTSP) is solved by an exact branch and bound method, where different lower bounds are presented by combining the solutions of a min-max set partitioning problem and of a Generalized Traveling Salesman Problem (GTSP). The second problem is approached by assuming that robots move synchronously: a novel transformation of this synchronous problem into a GTSP is presented. Eventually, in order to provide complete robot solutions, we include path planning functionalities, allowing the robots to avoid collisions with the static environment and among themselves. These steps are iterated until a satisfying solution is obtained. Experimental results are shown for both problems and for their combination. We even show the results of the iterative method, applied to an industrial test case adapted from a stud welding station in a car manufacturing line

Technology assessment of advanced automation for space missions

Six general classes of technology requirements derived during the mission definition phase of the study were identified as having maximum importance and urgency, including autonomous world model based information systems, learning and hypothesis formation, natural language and other man-machine communication, space manufacturing, teleoperators and robot systems, and computer science and technology