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  • 1.
    Adolfsson, Sebastian
    University West, Department of Engineering Science, Division of Production System.
    RatSLAM with Viso2: Implementation of alternative monocular odometer2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this work, a ROS (Robot Operating System) version of OpenRatSLAM, [1] [2], was tested with Viso2 [3] as an alternative monocular odometer. A land based rover [4] was used to perform data acquisition and a remote control tool was developed to facilitate this procedure, implemented as ROS nodes on both Ubuntu 16.04 and on Android 7.0.  An additional requirement that comes from using Viso2 is the need for camera information together with the image stream, which might require camera calibration. A ROS node to manually add this camera information was made as well as a node to change the generated odometry message from Viso2 to a form that RatSLAM uses. The implemented odometer uses feature tracking to estimate motion, which is fundamentally different to matching intensity profiles which the original method does and can hence be used when different properties of the visual odometry function is desired. From experiments, it was seen that the feature tracking method from Viso2 generated a more robust motion estimate in terms of real world scale and it was also able to better handle environments of varying illumination or that contains large continuous surfaces of the same colour. However, the feature tracking may give slight variations in the generated data upon successive runs due to the random selection of features to track. Since the structure of RatSLAM gives the system ability to make loop closures even with large differences in position, an alternative odometry does not necessarily give a significant improvement in performance of the system in environments that the original system operates well in. Even though both algorithms show difficulty with estimating fast rotations, especially when the camera view contains areas with few features, the performance improvement in Viso2 together with its ability to better maintain the real-world scale motivates its usefulness.  The source code, as well as instructions for installation and usage is public.

  • 2.
    Adolfsson, Sebastian
    University West, Department of Engineering Science, Division of Production System.
    RatSLAM with Viso2: Implementation of alternative monocular odometer2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this work, a ROS (Robot Operating System) version of Open RatSLAM, [1] [2], was tested with Viso2 [3] as an alternative monocular odometer. A land based rover [4] was used to perform data acquisition and a remote control tool was developed to facilitate this procedure, implemented as ROS nodes on both Ubuntu 16.04 and on Android 7.0.An additional requirement that comes from using Viso2 is the need for camera information together with the image stream, which might require camera calibration. A ROS node to manually add this camera information was made as well as a node to change the generated odometry message from Viso2 to a form that RatSLAM uses. The implemented odometer uses feature tracking to estimate motion, which is fundamentally different to matching intensity profiles which the original method does and can hence be used when different properties of the visual odometry function is desired. From experiments, it was seen that the feature tracking method from Viso2 generated amore robust motion estimate in terms of real world scale and it was also able to better handle environments of varying illumination or that contains large continuous surfaces of the same colour. However, the feature tracking may give slight variations in the generated data upon successive runs due to the random selection of features to track. Since the structure of RatSLAM gives the system ability to make loop closures even with large differences in position, an alternative odometry does not necessarily give a significant improvement in performance of the system in environments that the original system operates well in. Even though both algorithms show difficulty with estimating fast rotations, especially when the camera view contains areas with few features, the performance improvement in Viso2 together with its ability to better maintain the real-world scale motivates its usefulness. The source code, as well as instructions for installation and usage is public

  • 3.
    Aguilar Gómez, Raquel
    University West, Department of Engineering Science, Division of Automation Systems.
    Investigation of a Flexible Manufacturing Scenario for Production Systems: Case study: GKN Aerospace Company2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays the globalization of the market has a direct impact to the companies. On one hand, gives them the opportunity to spread their business but on the other hand increases the competition and the efforts to succeed. This project is pursuing to investigate and design a system capable to take upon and optimize the production within functional shops by in-troducing automation. Although the system it would be a standard solution for the functional shops, a case study for GKN Aerospace Company with its specifications has been carried out. The task become trickier due to the aeronautic sector requires a lot of work and effort to produce their products. The items and materials are expensive as well as the processes and treatments thus the introduction of automation is quite complex. This case study has accom-plished a research through the concepts and options to introduce automation within this production process. Taking under consideration the costs and efforts that would demand the investment for automation, the project propose a new and innovative manufacturing system "Move & Play", suitable with the features and requirements GKN Aerospace Company may need.The system proposed has been designed regarding to features such as movability, modularity and flexibility. These features have been considered essentials in order to make the system worth it and cost effective. The job-shop approach that the company use in its production contemplate the continuous change of products and introduction of new ones. Hence, the idea is to use the "Move & Play" system when it is required along the production. As a consequence, this system will create a "local product flow" along that point in the production that will organize the rest of the production or "global flow". Moreover it is expected to apply the concept of "plug-in" the processes that the system need at each time and therefore give flexibility to the system. With that purposes, the work has studied three different designs of the "Move & Play" system. Each design have considered different aspects and disposition. These designs have been compared according with criteria such as geometrical, the capacity and investment needed and the cycle time spent. Finally a conclusion on which design is the most suitable has been stated as well as a future work to continue with the work has been proposed.

  • 4.
    Al Hayani, Musab
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Offline Programming of Robots in Car Seat Production2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Company Purtech in Dals-Ed manufactures molded polyurethane (PUR). Examples of products that include polyurethane are car seats. Robots are used to fill the molds with PUR and to apply the release agent (wax) in the empty molds.

    Turning from online programming into a graphical offline programming of release agent spraying robots is going to simplify the process by:

    1. Applying less of release agent to avoid polluting environment, to produce an easier removal of moulds, for the sake of homogeneous moulds and for economical saving in the cost of release agent
    2. Adaption of spraying paths to variation in production speed.
    3. Programming of complex spraying trajectories to deal with sharp geometrical subsurface
    4. Decreasing onsite programming time (when program a new workpiece or modify an old one); so that robots would be free for production.

    While turning into offline programming brought the challenges of:

    1. Impact of variation in the production speed
    2. Lack of 3D models of workcell’s equipments
    3. Robot joint configuration when paths and robtargets are in move.
    4. Physical Joint limits, Singularities & Reach limits
    5. Collisions within the cell space.

    At the end, the following objectives are successfully met:

    1. Adaption of spraying programs to variation in production speed by developing and embedding a method in those programs.
    2. Graphical offline generation of spraying trajectories and optimization of those trajectories to the Purtech condition of spraying allowed time for each carrier.
    3. Simulation of release agent spraying process; and producing of a well structured RAPID program that reflect the simulated process.

              

  • 5.
    AlNabulsi, Yasan
    University West, Department of Engineering Science, Division of Production System.
    Robot motion control based on 3D mouse tracking2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The manufacturing industry and associated systems are being developed in an increasing manner to cover the market needs, where the manufacturing companies are continuously racing and competing to achieve high productivity rate and better production quality. In this thesis work, an advanced method for motion control of industrial robots has been investigated and implemented. This method is based on motion tracking of a 3DSpaceMouse, which was used to perform movements by the operator. The benefits and disadvantages of this method were discussed in this thesis work. It mainly showed a high accuracy in response to the motion applied by the 3DSpaceMouse, and a great stability regarding the programming environment that was used to build it. The movements applied by the 3DSpaceMouse were successfully captured and stored in variables in the programming platform. The capturing and storing process was successfully created as a package and prepared to be exported for usage by other software. Complete simulation was performed for an industrial robot, and successful communications among the various hardware and software components of this solution were accomplished. This has formed a complete integrated solution that has also included a user-friendly HRI. This HRI made it easy and simple to track the motion control processes and establish connections with the robot controller. Thus, it can be considered a feasible solution for motion control of industrial robots, which can be used by the manufacturing companies. Several tests and verification processes were carried out to obtain accepted results and to succeed in implementing a working model. Some errors and unexpected events have appeared during the work, which required handling in order to achieve a working integrated system.

  • 6.
    Antoine, Galluet
    University West, Department of Engineering Science, Division of Automation Systems.
    Kinect to control robot: New ways to interact with robots2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main goal of the thesis is to create a way to interact with a ABB robot by using a Kinect.The focus will be put on making the robot mimicking the user's arm movement. But otherway like voice control will be investigated.Two main part of the work are developed in this report. The first one is the software aroundthe Kinect to get the body data. The software developed provides the user a visual feedbackon what the Kinect see and allows him to choose what mode he wants to use. Two mainmode are implemented. A mimicking one which makes the robot mimicking the chosen armand a moving object mode which tell the robot to go to the user's position and set the toolas the user hand state.When all the data are gathered, they are sent to the robot using an IP socket and predefinedmessage to give him the desired order.

  • 7.
    Augustsson, Svante
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Human and Robot Interaction basedon safety zones in a shared work environment2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The work explores the possibility to increase the automation along a production line by introducing robots without reducing the safety of the operator. The introduction of a robot to a workstation often demands a redesign of the workstation and traditionally the introduction of physical safety solutions that can limit the access to the work area and object on the production line. This work aims to find a general solution that can be used not only in the construction industry, but also in other types of industries to allow for an increased Human and Robot Interaction (HRI) without physical safety solution. A concept solution of a dynamic and flexible robot cell is presented to allow for HRI based on safety zones in a shared work environment. The concepts are based on one robot and the usage of a 3D camera system allowing for the design of virtual safety zones, used to control the HRI. When an operator approaches the robots work area and triggers a safety zone the robot stops its work and moves away from the operator. Based on the safety requirements and triggered zones the robot will continue to work in a new area or wait until the operator leaves the work area and then continue with the interrupted work task. This will allow the operator and the robot to work together, where the operator location controls the robots workspace. Testing and validation of the presented concept showed that the wanted functionality could be obtained. It also showed limitations to the equipment and the system used during tests and raised additional aspects of the safety for HRI. Of the detected limitations the most crucial when looking at up-time for the production line, is the camera system need of a relatively dust free environment, good and constant lighting. For the safety of the system the limitation lies in the size and placing of the safety zones in combination with the disturbance from  surrounding equipment. The presented concept has proven to work, and can be applied not only for the construction industry but for all industries with manufacturing alongside production lines with large components.

  • 8.
    Augustsson, Svante
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Gustavsson Christiernin, Linn
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation Systems.
    Human and robot interaction based on safety zones in a shared work environment2014In: HRI '14: Proceedings of the 2014 ACM/IEEE international conference on Human-robot interaction, New York: Association for Computing Machinery (ACM), 2014, p. 118-119Conference paper (Refereed)
    Abstract [en]

    In this paper, early work on how to implement flexible safety zones is presented. In the case study an industrial robot cell emulates the environment at a wall construction site, with a robot performing nailing routines. Tests are performed with humans entering the safety zones of a SafetyEye system. The zone violation is detected, and new warning zones initiated. The robot retracts but continues its work tasks with reduced speed and within a safe distance of the human operator. Interaction is achieved through simultaneous work on the same work piece and the warning zones can be initiated and adjusted in a flexible way.

  • 9.
    Augustsson, Svante
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Olsson, Jonas
    University West, Department of Engineering Science, Division of Manufacturing Processes. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Gustavsson Christiernin, Linn
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    How to Transfer Information Between Collaborating Human Operators and Industrial Robots in an Assembly2014In: Proceedings the NordiCHI 2014: The 8th Nordic Conference on Human-Computer Interaction: Fun, Fast, Foundational, 2014, p. 286-294Conference paper (Refereed)
    Abstract [en]

    Flexible human-robot industrial coproduction will be important in many small and middle-sized companies in the future. One of the major challenges in a flexible robot cell is how to transfer information between the human and the robot with help of existing and safety approved equipment. In this paper a case study will be presented where the first half focus on data transfer to the robot communicating the human's position and movements forcing the robot to respond to the triggers. The second half focuses on how to visualize information about the settings and assembly order to the human. The outcome was successful and flexible, efficient coproduction could be achieved but also a number of new challenges were found.

  • 10.
    Benages Montolío, Sergio
    University West, Department of Engineering Science, Division of Automation Systems.
    Robot Behaviour Monitoring in Friction Stir Welding2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Friction Stir Welding is a solid state join process in which the heat need is produced by the friction of a tool on the work pieces. The tool rotates on the surface and also applies a force against it to create the needed friction. This technology does not use any consumable and does not produce any gas, which makes it cost effective, save for the operators and clean.

    The equipment used for this technology has been changing within the years. Milling machines were adapted to it at the beginning. After, specific machines for friction stir welding were developed, providing higher down force and control systems. Nevertheless, the lack of flexibility of machines made industrial robots became an alternative. Robots have limitations in terms of stiffness. But, they can be used to weld complex geometries and they can be used in large scale applications due to their flexibility and low cost.

    This project studies the process from the robot behaviour perspective. The main objective is to achieve a better understanding of the process to contribute to the continuous development of robotic FSW. An acquisition system was developed to monitor different signals from the robot such as, forces, torque, path deviation, and vibrations. The data acquisition system developed and mounted at PTC was tested and its limitations were examined. The developed system has been used for conducting different experiments: The differences between the robot system and a system based on a FSW machine situated at TWI were studied; and, in addition, the behaviour of the robot under different welding parameters was investigated.

  • 11.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Reconfigurable and Flexible Industrial Robot Systems2014In: Advances in Robotics & Automation, ISSN 2168-9695, Vol. 3, p. 117-Article, review/survey (Other academic)
    Abstract [en]

    This paper presents a concept for reconfigurable and flexible robot systems. To reach a technology readiness level where solutions and results can be implemented in industry, the focus in this work is on systems with limited number of robots, and work scenarios which are reasonable complex but hard to automate using standard solutions.Four distinct areas have been identified as important within the concept and further studies: (i) human machine interaction, (ii) safety including collaboration, (iii) programming and deployment, and (iv) planning and scheduling. Feasibility studies have been made which addressed issues (ii) and (iii), in scenarios with collaboration between robot and human, or between two robots. For the chosen work scenario, manufacturing of structures in wood for family houses, challenges related to programming and safety was identified and possible solutions outlined.The concept and the studies indicate that feasible solutions can be found and designed given a reasonable consistent work processes and products. In this study, the processes are similar, nailing and screwing but different sizes may apply, the material is similar but variations may apply, and the construction is different of each product, but include the same type of operations at different locations. Our study confirm that human collaboration improves the ability to implement and use robots as it make it possible to move some operations to the human which otherwise would add to the complexity of the system. Furthermore, programming can also I general be simplified although methods for automatic programming has been tried out. But in some cases, the solution space is limited and the ability to move certain operations to a human simplifies the programming task. However, further work needs to be done in this area specifically related to safety issues for safe collaboration.

  • 12.
    Bolmsjö, Gunnar
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Collaborative Robots to Support Flexible Operation in a Manufacturing System2012In: Flexible Automation and Intelligent Manufacturing, FAIM 2012 / [ed] Hasse Nylund, Satu Kantti, Ville Toivonen, Seppo Torvinen, Tampere University, Finland, 2012, p. 531-538Conference paper (Refereed)
    Abstract [en]

    Collaborative robotic systems where human(s) and robot(s) cooperate in performing a common task is an attractive solution to introduce automation combined with high flexibility for tasks that have a high complexity and characterized by low volume or down to one-off. By introducing collaboration in robotics systems, the operator can complement with cognitive capacity and skill in order to gain in flexibility and agility in the task operation. This paper describes on-going work related to work on collaboration between operator and robot. User scenarios are outlined together with methods, software components and hardware to support collaboration, where some of these are under development. As the standards related to collaborative robotic systems are soon to be completed, it is expected that this type of semi-automatic systems will be important for flexible and agile automation of production which otherwise cannot be automated.

  • 13.
    Carlsson, Henrik
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Reliable Virtual Commissioning2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Virtual commissioning is a technique for programming, optimising and verifying industrial automated production, such as robot controllers and programmable logic controllers (PLC), off-line in a simulated environment. Compared with traditional robot off-line programming and simulation, the scope is wider and can include an entire production cell.

    Robot simulation is a well-established technique and widely used in industry today, much thanks to the RRS interface that enables simulated robot control systems to be integrated in the simulation software. A more general interface for industrial control system integration is OPC that has been an industrial de facto standard for connection between industrial control systems and regular PCs. State-of-the-art production simulation tools often include the possibility to connect an industrial control system via OPC. However, OPC suffers a major drawback when it comes to production simulation, there is no mechanism that synchronises the industrial control system with the simulation and this could lead to unreliable results from the simulation.

    Another obstacle for virtual commissioning is the amount of time that needs to be spent during the simulation model building phase, since virtual commissioning includes more signals. This does not only take more time, but it is also an error prone process that might lead to unreliable results.

    In this thesis problems related to the OPC interface and the modelling process are discussed, and suggestions how these issues can be solved are presented so reliable virtual commissioning can be achieved.

  • 14.
    Carlsson, Henrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Nilsson, Jim
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Automated Generation of Discrete Event System Simulation Models for Flexible Automation2011In: The 21st International Conference on Flexible Automation and Intelligent Manufacturing: Taichung, Taiwan, June 26-29 2011, 2011, p. 825-832Conference paper (Refereed)
    Abstract [en]

    Flexible automation cells with rapid product changes are an important competitive advantage for industries today. These cells can increase a company’s productivity and thereby increase their profits. A flexible cell shall be able to handle different products with none or minimal changes to the cell itself. A powerful tool, which can be used to analyse and verify such cells, is discrete event system simulation. Problems such as potential bottlenecks, deadlocks, answers to "what-if" questions and the level of resource utilisation can be gathered. The drawback of discrete event system simulation is that the modelling task is both time consuming and difficult to accomplish. Furthermore, state-of-the-art discrete event system simulation tools that are used in the industry today are not suitable for flexible automation. If the production scenario is changed, e.g. introduction of a new product, the simulation and modelling has to be redone and this is both time consuming and tedious. In this paper a new approach will be presented that enables discrete event simulation models to be generated automatically. The models are generated from information retrieved from a PLM/PDM database system, which is shared among other engineering tools such as robot simulation, CAD and process planning. Hence, when the cell and the database are updated a new model can easily be generated. The database is also connected to the real cell so up-to-date data can be retrieved from the real cell. The model generator described in this paper was implemented and tested in a discrete event system simulation tool and showed promising results. With this approach it is possible to handle flexible automation cells more effectively in a process planning stage.

  • 15.
    Carlsson, Henrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    Chalmers University of Technology, Department of Signals and Systems.
    Methods for Reliable Simulation-Based PLC Code Verification2012In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, ISSN 1551-3203, Vol. 8, no 2, p. 267-278Article in journal (Refereed)
    Abstract [en]

    Simulation based PLC code verification is a part of virtual commissioning, where the control code is verified against a virtual prototype of an application. With today’s general OPC interface it is easy to connect a PLC to a simulation tool for e.g. verification purposes. However, there are some problems with this approach that can lead to an unreliable verification result. In this paper, four major problems with the OPC interface are described, and two possible solutions to the problems are presented: a general IEC 61131-3 based software solution, and a new OPC standard solution

  • 16.
    Charles Murgau, Corinne
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Pederson, R.
    Luleå University of Technology, Division of Material Science.
    Lindgren, L. E.
    Luleå University of Technology, Division of Material Mechanics.
    A model for Ti-6Al-4V microstructure evolution for arbitrary temperature changes2012In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 20, no 5, p. 055006-Article in journal (Refereed)
    Abstract [en]

    This paper presents a microstructure model for the titanium alloy Ti-6Al-4V designed to be used in coupled thermo-metallurgical-mechanical simulations of, e.g., welding processes. The microstructure evolution is increasingly taken into consideration in analyses of manufacturing processes since it directly affects the mechanical properties. Thermally driven phase evolutions are accounted for in the model. A state variable approach is adopted to represent the microstructure with the objective to integrate the microstructure changes with a thermomechanical model of manufacturing process simulation such as welding. The model is calibrated using the literature data and also validated against a cyclic temperature history during multi-pass welding.

  • 17.
    Choquet, Isabelle
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Javidi-Shirvan, Alireza
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Nilsson, Håkan
    Chalmers University of Technology, Department of Applied Mechanics, .
    Magnetic field models for high intensity arcs, applied to welding: A comparison between three different formulations2013In: ASM Proceedings of the International Conference: Trends in Welding Research 2013, Chicago, IL: ASM International, 2013, p. 876-885Conference paper (Refereed)
    Abstract [en]

    Most simulation studies done to deeper understand high-intensity welding arcs address axi-symmetric configurations and use the electric potential formulation. This formulation involves the assumption of a one-dimensional magnetic field. The assumption is justified in its original frame: rather long arcs (about 10 mm), and when the electrode tip is excluded from the computational domain. However, arcs applied to welding are shorter, and the electrode geometry is important to take into account. The present work questions the assumption of a one-dimensional magnetic field for simulating short welding arcs. We have compared three different approaches for modeling the magnetic field: three-dimensional, two-dimensional axi-symmetric, and the electric potential formulation. These models have been applied to water cooled anode Gas Tungsten Arc Welding (GTAW) test cases with truncated conical electrode tip (tip radius of 0.5 and 0.2 mm) and various arc lengths (2, 3 and 5 mm). For the axi-symmetric cases studied in the present work, the three- and two-dimensional models give exactly the same results. The one-dimensional simplification of the magnetic field turns out to have a significant unfavorable effect on the simulation results. For axi-symmetric welding applications, it is argued that the two-dimensional axi-symmetric formulation should be used. Copyright © 2013 ASM International® All rights reserved.

  • 18.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Haijun, Xing
    University West.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    A Simulation-Based Optimization Approach for Holonic Manufacturing Systems2012In: Flexible Automation and Intelligent Manufacturing, FAIM 2012: Helsinki, 10-13 June / [ed] Hasse Nylund, Satu Kantti, Ville Toivonen, Seppo Torvinen, Tampere University, Finland, 2012, p. 515-522Conference paper (Refereed)
    Abstract [en]

    Holonic Manufacturing System (HMS) is an integrated multi-agent technology that represents the developing direction in the automation field. HMS can be represented as a non-hierarchical manufacturing architecture with no or limited supervision. However, it is a challenge for a single holon in a non-hierarchical system to make globally optimal decisions. This paper presents a simulation-based optimization method for HMS by introducing a new wizard holon. A wizard holon collects the necessary information from the entire HMS and uses Discrete Event System (DES) simulation to evaluate the cost of different decisions. Since a non-hierarchical approach is used the wizard input is only treated as an advice to achieve more globally optimal decisions. The decisions are still taken by the local holon. Even for an experienced operator it might be hard to predict the outcome of a decision in a critical situation. Hence, wizard advices are valuable for all types holons, including machines, robots, and operators.

  • 19.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Flexible Robotized Automation in Manufacturing Systems2011In: The 21st International Conference on Flexible Automation and Intelligent Manufacturing: Taiwan, 26-29 June 2011, 2011, p. 207-214Conference paper (Refereed)
    Abstract [en]

    Due to constant changes in the market there is a need for low-cost and low-volume manufacturing. Usually this type of production is difficult to automate due to the time it takes to become profitable and the inflexibility of such solutions. Therefore, flexible automation solutions need to be addressed together with cost effective aspects. In this paper, a new concept for the design of a flexible, robotized solution based on lean automation is presented and simulated. The proposed lean automation concept is formed of standardized robot stations, human-robot collaboration and cost effective level of automation. The main goals are flexible automated production system and reduced production cost. This paper shows that the proposed flexible lean automation concept has some key advantages compared to the traditional robot cells; a longer lifetime for the robot cell as well as being easier to re-balance, introduce new parts to and expand the cell. Further, it also shows that the proposed concept reduces the cost for automation of products with low volume.

  • 20.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    He, Jun
    University West.
    Integration of humans into a multi-agent system2013In: ESM'2013 The 2013 European Simulation and Modelling Conference / [ed] Stephan Onggo and Antonin Kavicka, Ostend, Belgien: EUROSIS-ETI Publication , 2013, p. 257-259Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to describe on-going work in the integration of humans in automated manufacturing systems. The intention is to achieve a flexible manufacturing system to meet the rapid developing and changing of today’s industry. The approach is based on a control concept with multi-agents. Humans, which are considered as a valuable factor in industrial production, are proposed as flexible agent resources for the automated manufacturing system.

    A test case was performed on a manufacturing system where three different groups of humans where integrated in the system; inspection, carrier and recovery. The P-SOP agent generator was used to automatically generate IEC 61131-3 PLC control code for the system.

  • 21.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation Systems.
    Reddy, Dhanush
    University West, Department of Engineering Science, Division of Automation Systems.
    A genetic algorithm with shuffle for job shop scheduling problems2015In: Modelling and simulation 2015: The European simulation and modelling conference 2015, ESM 2015, October 26-28 Leicester, United Kingdom / [ed] Marwan Al-Akaidi & Aladdin Ayesh, Ostend: ESM , 2015, p. 363-367Conference paper (Refereed)
    Abstract [en]

    Job shop scheduling problems are computationally complex combinatorial optimization problems. Genetic algorithms have been used in various forms and in combination with other algorithms to solve job shop scheduling problems. A partially flexible job shop with precedence constraints increases this complex behaviour. There are two main parts to optimizing ajob shop, the routing and the scheduling. The objective here is to get consistent optimal makespan using a genetic algorithm. This paper firstly, presents a simulation approach for the considered partially flexible job shop scheduling problem. Which take into account the precedence constraints and reduce situations of deadlock. To solve the partially flexible job shop scheduling problem a genetic algorithm was used and improved. It utilise a genetic crossovers for routing and a new random shuffle feature is introduced for the scheduling. The computational results have shown that the algorithm performs well in terms of finding a consistent optimal schedule for the given problem

  • 22.
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Robotic Friction Stir Welding for Flexible Production2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Friction Stir Welding (FSW) is a modern welding process that joins materials by frictional heat, generated by a rotating tool. Unlike other welding processes, the material never melts, which is beneficial for the weld properties. FSW is already widely adopted in several industries but the applications are limited to simple geometries like straight lines or circular welds, mostly in aluminium. The welding operation is performed by rigid FSW machines, which deliver excellent welds but puts limitations on the system in terms of flexibility and joint geometries. Therefore, several research groups are working on the implementation of the FSW process on industrial robots. A robot allows welding of three-dimensional geometries and increases the flexibility of the whole system. The high process forces required for FSW, in combination with the limited stiffness of the robot brings some extra complexity to the system.  The limitations of the robot system are addressed in this licentiate thesis.

    One part of the thesis studies the effect of robot deflections on the weld quality. A sensor-based solution is presented that measures the path deviation and compensates this deviation by modifying the robot trajectory. The tool deviation is reduced to an acceptable tolerance and root defects in the weld are hereby eliminated. The sensor-based method provided better process understanding, leading to a new strategy that uses existing force-feedback for path compensations of the tool. This method avoids extra sensors and makes the system less complex. Another part of this work focuses on the extra complexity to maintain a stable welding process on more advanced geometries. A model is presented that allows control of the heat input in the process by control of the downforce. Finally, the robot’s limitations in terms of maximal hardness of the materials to be welded are investigated. Parameter tuning and implementation of preheating are proposed to allow robotic FSW of superalloys.

  • 23.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Thermoelectric method for temperature measurement in friction stir welding2013In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 18, no 7, p. 541-550Article in journal (Refereed)
    Abstract [en]

    Previous research within friction stir welding (FSW) has demonstrated that online control of welding parameters can improve the mechanical properties and is necessary for certain applications to guarantee a consistent weld quality. One approach to control the process is by adapting the heat input to maintain a stable welding temperature, within the specified operating boundaries. This requires accurate in-process temperature measurements. This paper presents a novel method to measure the temperature at the interface of the FSW tool and workpiece. The method is based on the thermoelectric effect between dissimilar materials. The measurements are compared to thermocouple measurements and to a physical model and show good correspondence to each other. Experiments demonstrate that the method can quickly detect temperature variations, due to geometrical variations of the workpiece or due to parameter changes. This allows use of the method for online control of robotic FSW.

  • 24.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Temperature control of robotic friction stir welding using the thermoelectric effect2014In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 70, no 1-4, p. 375-383Article in journal (Refereed)
    Abstract [en]

    Friction stir welding (FSW) of non-linear joints receives an increasing interest from several industrial sectors like automotive, urban transport and aerospace. A force-controlled robot is particularly suitable for welding complex geometries in lightweight alloys. However, complex geometries including three-dimensional joints, non-constant thicknesses and heat sinks such as clamps cause varying heat dissipation in the welded product. This will lead to changes in the process temperature and hence an unstable FSW process with varying mechanical properties. Furthermore, overheating can lead to a meltdown, causing the tool to sink down into the workpiece. This paper describes a temperature controller that modifies the spindle speed to maintain a constant welding temperature. A newly developed temperature measurement method is used which is able to measure the average tool temperature without the need for thermocouples inside the tool. The method is used to control both the plunging and welding operation. The developments presented here are applied to a robotic FSW system and can be directly implemented in a production setting.

  • 25.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation Systems.
    Surface Quality and Strength in Robotic Friction Stir Welding of Thin Automotive Aluminium Alloys2011In: The 4th International Swedish Production Symposium / [ed] Jan-Eric Ståhl, The Swedish Production Academy , 2011, p. 554-562Conference paper (Refereed)
    Abstract [en]

    Friction Stir Welding (FSW) is a novel method for joining materials without using consumablesand without melting the materials. It uses a rotating tool that creates frictionalheat and mixes the materials mechanically together. Robotic application of FSW allowsthree-dimensional welding of light-weight metals in e.g. the automotive industry. TheStiRoLight project is driven by Saab Automobile AB and performed at University Westfor investigation of robotic FSW of three-dimensional welding seams. It aims to introduceFSW in the automotive production line. This paper describes the effect of penetrationdepth of the FSW tool during force controlled robotic welding of thin (< 2 mm) aluminium inoverlap configuration. The influence of pin length on strength of welded aluminium sheetsis investigated using tensile and peel tests. The main limiting factor for penetration depthis the surface quality on the backside of the weld, which often is important in automotiveapplications. Further, the roughness of the plates on the backside is measured and relatedto pin length and backing bar properties. This paper shows a relation between penetrationdepth and tensile strength, and suggests an optimal pin length to guarantee a good weldquality while maintaining an acceptable surface quality. The influence of sheet thicknesstolerance is also discussed. Knowledge is fed back to designers and manufacturingengineers to facilitate for use in production with guaranteed product quality.

  • 26.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Process and Product Development.
    Oqueka, Jens
    University West, Department of Engineering Science.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Investigation of path compensation methods for robotic friction stir welding2012In: Industrial robot, ISSN 0143-991X, E-ISSN 1758-5791, Vol. 39, no 6, p. 601-608Article in journal (Refereed)
    Abstract [en]

    Purpose – Friction stir welding (FSW) is a novel method for joining materials without using consumables and without melting the materials. The purpose of this paper is to present the state of the art in robotic FSW and outline important steps for its implementation in industry and specifically the automotive industry.

    Design/methodology/approach – This study focuses on the robot deflections during FSW, by relating process forces to the deviations from the programmed robot path and to the strength of the obtained joint. A robot adapted for the FSW process has been used in the experimental study. Two sensor-based methods are implemented to determine path deviations during test runs and the resulting welds were examined with respect to tensile strength and path deviation.

    Findings – It can be concluded that deflections must be compensated for in high strengths alloys. Several strategies can be applied including online sensing or compensation of the deflection in the robot program. The welding process was proven to be insensitive for small deviations and the presented path compensation methods are sufficient to obtain a strong and defect-free welding joint.

    Originality/value – This paper demonstrates the effect of FSW process forces on the robot, which is not found in literature. This is expected to contribute to the use of robots for FSW. The experiments were performed in a demonstrator facility which clearly showed the possibility of applying robotic FSW as a flexible industrial manufacturing process.

  • 27.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Production System. TWI Ltd, Cambridge, UK.
    Martin, Jonathan
    TWI Ltd, Cambridge, UK.
    Wei, Sam
    TWI Ltd, Cambridge, UK.
    Robotic Stationary Shoulder FSW: benefits and limitations2016In: Conference proceedings of the 11th International Symposium on Friction Stir Welding, 2016Conference paper (Refereed)
  • 28.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Soron, Mikael
    ESAB Welding AB .
    Three-dimensional friction stir welding of Iconel 718 using the ESAB Rosio FSW-robot2012Conference paper (Refereed)
  • 29.
    De Backer, Jeroen
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Soron, Mikael
    ESAB Welding AB .
    Cederqvist, Lars
    Influence of side-tilt angle on process forces and lap joint strength in robotic friction stir welding2012Conference paper (Refereed)
  • 30.
    Denys, Kristof
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Circular motion for robotized metal deposition: verification and implementation2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Metal deposition is an additive layered manufacturing process that deposits molten metal droplets on a substrate and by repeating this process layer by layer, a complex shaped 3D geometry can be manufactured.

    In this thesis, the metal deposition process is performed by a robot with a wire feeder tool and a laser as energy source to melt the metal wire. The robot programming for robotized metal deposition process can be completely automated by computer aided robotics software. University West is currently developing an add-in application in a computer aided robotics software, Process Simulate, that is capable of programming the robotized metal deposition process.

    The first goal of this thesis was to verify the up to now developed software and the process from CAD drawing down to robot code. Another goal was to find and implement an algorithm that will reduce the number of locations on a circular arc to three locations.

    The algorithm to minimize the locations must be capable of changing all the different curvature paths to linear and circular arc motions which are easy to translate to robot code. The user should be able to decide the fitting precision of the approximated motion path to the original path.

    A real robot cell setup is modelled in Process Simulate. This lets Process Simulate generate the correct robot code for that specific cell.  Since each robot cell has its own unique setup, a custom script will be developed that changes the universal robot code, that Process Simulate generates, to the custom robot code required in this specific robot cell.

    The software is improved and tested from CAD drawing down to robot code but still needs to be debugged more and needs implementation of some non-existing features.

  • 31.
    Glorieux, Emile
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Parthasarathy, Prithwick
    University West, Department of Engineering Science, Division of Production System.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Production System.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production System.
    Energy Consumption Model for 2D-Belt Robots2016In: 7th Swedish Production Symposium Conference proceedings, Lund: SPS16 , 2016, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Production that incorporates robotics consumes energy and the trend today is to reduce consumed energy not only to lower the cost but also to be a more energy efficient entity. Energy models can be used to predict the energy consumed by robot(s) for optimising the input parameters which determine robot motion and task execution. This paper presents an energy model to predict the energy consumption of 2D-belt robots used for press line tending. Based on the components’ specifications and the trajectory, an estimation of the energy consumption is computed. The capabilities of the proposed energy model to predict the energy consumption during the planning-phase (i.e. before installation), avoiding the need for physical experiments, are demonstrated. This includes predicting potential energy reductions achieved by reducing the weight of the gripper tools. Additionally, it is also shown how to investigate the energy saving achieved by using mechanical brakes when the robot is idle. This effectively illustrates the purpose and usefulness of the proposed energy model.

  • 32.
    Glorieux, Emile
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Riazi, Sarmad
    Department of Signals and Systems, Chalmers University of Technology, S-412 96 Gothenburg, Sweden.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Production System. Department of Signals and Systems, Chalmers University of Technology, S-412 96 Gothenburg, Sweden.
    Productivity/energy optimisation of trajectories and coordination for cyclic multi-robot systems2018In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 49, p. 152-161Article in journal (Refereed)
    Abstract [en]

    The coordination of cyclic multi-robot systems is a critical issue to avoid collisions but also to obtain the shortest cycle-time. This paper presents a novel methodology for trajectory and coordination optimisation of cyclic multi-robot systems. Both velocity tuning and time delays are used to coordinate the robots that operate in close proximity and avoid collisions. The novel element is the non-linear programming optimisation model that directly co-adjusts the multi-robot coordination during the trajectory optimisation, which allows optimising these as one problem. The methodology is demonstrated for productivity/smoothness optimisation, and for energy efficiency optimisation. An experimental validation is done for a real-world case study that considers the multi-robot material handling system of a multi-stage tandem press line. The results show that the productivity optimisation with the methodology is competitive compared to previous research and that substantial improvements can be achieved, e.g. up to 50% smoother trajectories and 14% reduction in energy consumption for the same productivity. This paper addresses the current lack of systematic methodologies for generating optimal coordinated trajectories for cyclic multi-robot systems to improve the productivity, smoothness, and energy efficiency.

  • 33.
    Glorieux, Emile
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Production System.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production System.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Production System. Department of Signals and Systems, Chalmers University of Technology, S-412 96 Gothenburg, Sweden.
    Constructive cooperative coevolution for large-scale global optimisation2017In: Journal of Heuristics, ISSN 1381-1231, E-ISSN 1572-9397, Vol. 23, no 6, p. 449-469Article in journal (Refereed)
    Abstract [en]

    This paper presents the Constructive Cooperative Coevolutionary ( C3C3 ) algorithm, applied to continuous large-scale global optimisation problems. The novelty of C3C3 is that it utilises a multi-start architecture and incorporates the Cooperative Coevolutionary algorithm. The considered optimisation problem is decomposed into subproblems. An embedded optimisation algorithm optimises the subproblems separately while exchanging information to co-adapt the solutions for the subproblems. Further, C3C3 includes a novel constructive heuristic that generates different feasible solutions for the entire problem and thereby expedites the search. In this work, two different versions of C3C3 are evaluated on high-dimensional benchmark problems, including the CEC'2013 test suite for large-scale global optimisation. C3C3 is compared with several state-of-the-art algorithms, which shows that C3C3 is among the most competitive algorithms. C3C3 outperforms the other algorithms for most partially separable functions and overlapping functions. This shows that C3C3 is an effective algorithm for large-scale global optimisation. This paper demonstrates the enhanced performance by using constructive heuristics for generating initial feasible solutions for Cooperative Coevolutionary algorithms in a multi-start framework.

  • 34.
    Glorieux, Emile
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Production System.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production System.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Production System. Department of Signals and Systems, Chalmers University of Technology,Gothenburg, Sweden.
    Multi-objective constructive cooperative coevolutionary optimization of robotic press-line tending2017In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 49, no 10, p. 1685-1703Article in journal (Refereed)
    Abstract [en]

    This article investigates multi-objective optimization of the robot trajectories and position-based operation-coordination of complex multi-robot systems, such as press lines, to improve the production rate and obtaining smooth motions to avoid excessive wear of the robots’ components. Different functions for handling the multiple objectives are evaluated on realworld press lines, including both scalarizing single-objective functions and Pareto-based multi-objective functions. Additionally, the Multi-Objective Constructive Cooperative Coevolutionary (moC3) algorithm is proposed, for Pareto-based optimization, which uses a novel constructive initialization of the subpopulations in a co-adaptive fashion. It was found that Paretobased optimization performs better than the scalarizing single-objective functions. Furthermore, moC3 gives substantially better results compared to manual online tuning, as currently used in the industry. Optimizing robot trajectories and operation-coordination of complex multi-robot systems using the proposed method with moC3 significantly improves productivity and reduces maintenance. This article hereby addresses the lack of systematic methods for effectively improving the productivity of press lines.

  • 35.
    Glorieux, Emile
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation Systems.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Automation Systems.
    Simulation-based Time and Jerk Optimisation for Robotic Press Tending2015In: Modellling and Simulation: The European simulation and modelling conference 2015, ESM 2015, Ostende: ESM , 2015, p. 377-384Conference paper (Refereed)
    Abstract [en]

    Increased production rate and robot motion smoothness in a sheet metal press line are essential. Smooth robot motions avoid unplanned production interruptions and excessive wear of the robots. Reaching high production rate and smooth motions requires tuning of the tending press robot control to minimise the cycle time and jerk. Doing this for a press line with multiple robots is a complex large-scale problem. To model such problems for the optimisation process, computer simulations become almost essential. This work presents simulation-based optimisation of the time and jerk of robotic press tending operations and investigates the importance of including the robot motion’s smoothness. An optimiser works in concert with a simulation model of a sheet metal press line and its parametrised control system. The effect of including jerk minimisation in the objective function is tested on a real-world problem concerning a sheetmetal press line. The results illustrate the importance of including jerk-minimisation as an objective in the optimisation.Furthermore, the performance of this approach is compared with manual tuning by experienced operators. The results show that the proposed simulation-based optimisation approach outperforms manual tuning.

  • 36.
    Glorieux, Emile
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Production System.
    Parthasarathy, Prithwick
    University West, Department of Engineering Science, Division of Production System.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production System.
    An energy model for press line tending robots2016In: ESM'2016, the 2016 European simulation and Modelling Conference: Modelling and Simulation '2016 / [ed] José Evora-Gomez & José Juan Hernandez-Cabrera, Eurosis , 2016, p. 377-383Conference paper (Refereed)
    Abstract [en]

    Today most industries aim at reducing energy consumption to become sustainable and environment-friendly. The automotive industry, with mass production and large volumes, is one such example. With many robots working round the clock, there is great potential to save energy. In this climate there is a need for robot simulation models that can be used for motion and task execution optimisation and which are aimed lowering energy consumption. This paper presents an energy consumption model for 2D-belt robots for press line tending in the automotive sector. The energy model is generic for 2D-belt robots and is entirely based on component specifications (e.g., dimensions, masses, inertia). An implementation and validation against a real 2D-belt tending robot used in the automotive industry is performed and presented. The purpose and usefulness of the energy model is also demonstrated by two application cases; the investigation of potential energy reductions achieved by reducing the weight of gripper tools, and by using mechanical brakes when the robot is idle.

  • 37.
    Gustavsson Christiernin, Linn
    University West, Department of Engineering Science, Division of Production System.
    How to describe interaction with a collaborative robot2017In: HRI '17 Proceedings of the Companion of the 2017 ACM/IEEE International Conference on Human-Robot Interaction, IEEE Computer Society , 2017, p. 93-94Conference paper (Refereed)
    Abstract [en]

    In this paper, we describe early work on a classification model on how to interact with industrial and other types of robots. We suggest a classification for how to describe different scenarios within Human-Robot Interaction. The idea with this model is to help when identifying the gap between where a company is and where they would like to be when it comes to collaborative automation. © 2017 Author.

  • 38.
    Hagqvist, Petter
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Instrumentation and estimation for high temperature control2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within a variety of industrially relevant high temperature production processes such as welding, heat treatment and metal deposition, the quality of the manufactured component is largely affected by how well parameters can be controlled during processing. These parameters might be, in the case of metal deposition, power input, material feed, or a parameter which is common for all of the aforementioned processes: material temperature. The ability to correctly measure, or in other ways estimate process parameters is vital in order to successfully control high temperature processes such as above 700 degrees Celsius. In this work, instrumentation and estimation solutions adapted to high temperature control are proposed and implemented with a focus on the laser metal wire deposition process. Special attention is given to temperature measurements on specimens with varying emissivity as commonly found in high temperature processes. A calibration procedure for a single-wavelength pyrometer is also presented together with a general discussion on limitations of such a system for measurands with varying emissivity. A new method for non-contact emissivity compensated temperature estimations using a spectrometer is presented. Simulations and industrially relevant experiments have been carried out validating the method. The theoretical framework for the developed method will be further investigated in the future together with additional experimental validation. In addition to temperature measurements, a method for real-time process control of laser metal wire deposition has been developed and implemented with good results. This control scheme estimates and controls the tool-to-workpiece distance based on resistance measurements. Such measurements allow for placement of instruments outside of the processing chamber and easy integration into existing equipment. Future work will be directed towards incorporation of resistance measurements into an iterative learning control scheme. Also, improvement on the resistance-distance model and further investigation into suitable signal processing methods for the resistance signal will be pursued.

  • 39.
    Hagqvist, Petter
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Automatic detection of material phase transitions from spectroscopic data2013In: Proceedings of the IECON 2013: 39th Annual Conference of the IEEE Industrial Electronics Society, 2013, p. 2384-2389Conference paper (Refereed)
    Abstract [en]

    When using a temperaturemeasurementmethod which utilizes spectral information for measuring the temperature of varying emissivity measurands, there is a need for a temperature reference at some point in time. In this work, such a reference is created from the spectral radiance data already used by the temperature measurement method. A method of using knowledge of the measurand material's phase transitions and spectral radiance data as a temperature reference is presented. Through automatical identification of phase transitions from radiance spectra employing signal processing, the temperature is known at a certain instance in time, just like required by the temperature measurement method. Three methods for automatic identification of material phase transitions from spectroscopic data are examined and evaluated. The methods are, based on derivatives, steady-state identification and cross correlation respectively. They are introduced and evaluated using experimental data collected from a solidifying copper sample. All methods proved to identify the phase transitions correctly. The addition of automatic phase transition identification supplements the existing temperature measurement method such that it becomes a stand alone, reference free method for measuring the true absolute temperature of a measurand with varying emissivity.

  • 40.
    Hagqvist, Petter
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Heralic, Almir
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers.
    Resistance measurements for control of laser metal wire deposition2014In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 54, no March, p. 62-67Article in journal (Refereed)
    Abstract [en]

    A method for controlling robotized laser metal wire deposition online by electrical resistance metering is proposed. The concept of measuring the combined resistance of the wire and the weld pool is introduced and evaluated for automatic control purposes. Droplet formation, detachment of the wire from the weld pool and stubbing can be hard to avoid during processing due to the sensitive process and short reaction times needed for making on-line adjustments. The implemented system shows a possible route for automatic control of the process wherein such problems can be avoided automatically. The method proves to successfully adjust the distance between the tool and the workpiece through controlling the robot height position, thus increasing stability of the laser metal wire deposition process.

  • 41.
    Hagqvist, Petter
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Sikström, Fredrik
    University West, Department of Engineering Science, Division of Process and Product Development.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers.
    Emissivity compensated spectral pyrometry for varying emissivity metallic measurands2014In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 25, no 2, p. 025010-Article in journal (Refereed)
    Abstract [en]

    A novel method for converting electromagnetic spectral radiance information into emperature measurements is presented. It allows for varying spectral emissivity of the metallic measurand during the course of the measurement. Such variations are due to e.g. thermal oxidation or temperature dependent emissivity. Based on the assumption that emissivity changes with time and temperature in a continuous manner, it is further assumed that an emissivity estimate at one sample instance can be derived from the estimated emissivity found at the previous samples together with updated spectral information. This leads to successive recalculations of spectral emissivity together with corresponding temperature values. The proposed algorithm has been proven to give accurate temperature estimates from a measurement based on data captured by a standard UV-Vis spectrophotometer even for an oxidizing Ti-6Al-4V specimen in a temperature range between 900K and 1400K. The method however, is not limited to these wavelength- or temperature-ranges.

  • 42.
    Hagqvist, Petter
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Sikström, Fredrik
    University West, Department of Engineering Science, Division of Process and Product Development.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers.
    Emissivity compensated spectral pyrometry-algorithm and sensitivity analysis2014In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 25, no 2, p. 025011-Article in journal (Refereed)
    Abstract [en]

    In order to solve the problem of non-contact temperature measurements on an object with varying emissivity, a new method is herein described and evaluated. The method uses spectral radiance measurements and converts them to temperature readings. It proves to be resilient towards changes in spectral emissivity and tolerates noisy spectral measurements. It is based on an assumption of continuous changes in emissivity and uses historical values of spectral emissivity and temperature for estimating current spectral emissivity.

    The algorithm, its constituent steps and accompanying parameters are described and discussed. A thorough sensitivity analysis of the method is carried out through simulations. No rigorous instrument calibration is needed for the presented method and is therefore industrially tractable.

  • 43.
    Heralic, Almir
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Monitoring and Control of Robotized Laser Metal-Wire Deposition2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis gives a number of solutions towards full automation of the promising manufacturing technology Robotized Laser Metal-wire Deposition (RLMwD). RLMwD offers great cost and weight saving potentials in the manufacturing industry. By metal deposition is here meant a layered manufacturing technique that builds fully-dense structures by melting metal wire into solidifying beads, which are deposited side by side and layer upon layer. A major challenge for this technique to be industrially implemented is to ensure process stability and repeatability. The deposition process has shown to be extremely sensitive to the wire position and orientation relative to the melt pool and the deposition direction. Careful tuning of the deposition tool and process parameters are therefore important in order to obtain a stable process and defect-free deposits. Due to its recent development, the technique is still manually controlled in industry, and hence the quality of the produced parts relies mainly on the skills of the operator. The scientific challenge is therefore to develop the wire based deposition process to a level where material integrity and good geometrical fit can be guaranteed in an automated and repeatable fashion. This thesis presents the development of a system for on-line monitoring and control of the deposition process. A complete deposition cell consisting of an industrial robot arm, a novel deposition tool, a data acquisition system, and an operator interface has been developed within the scope of this work. A system for visual feedback from the melt pool allows an operator to control the process from outside the welding room. A novel approach for automatic deposition of the process based on Iterative Learning Control is implemented. The controller has been evaluated through deposition experiments, resembling real industrial applications. The results show that the automatic controller increases the stability of the deposition process and also outperforms a manual operator. The results obtained in this work give novel solutions to the important puzzle towards full automation of the RLMwD process, and full exploitation of its potentials.

  • 44.
    Heralic, Almir
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Charles Murgau, Corinne
    University West, Department of Engineering Science, Division of Production Engineering.
    Dzevad, Imamovic
    Volvo Aero Coorporation.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    Dep of signal and systems, Chalmers.
    Towards stable high-speed metal-wire deposition, Part I: Parameter studyIn: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387Article in journal (Refereed)
  • 45.
    Heralic, Almir
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Automatic in-process control of laser metal-wire deposition based on sensor feedback2011In: 30th Interantional Congress on Applications of Lasers & Electro-Optics, ICALEO 2011: Orlando October 23-27, 2011. Code 87581|, 2011, p. 211-220Conference paper (Refereed)
    Abstract [en]

    This paper describes alasermetaldepositionsystem that isbasedon robotizedlaserwelding andwirefiller material. The system has been found suitable for the manufacture of simple but large shapes with high metallurgical requirements such as bosses or flanges found on aero engine components. Several benefits have been identified with the usage ofwirefiller compared to powderized feedstock, such as betterprocessefficiency, higherdepositionrates, and cleaner working environment. Thewirebaseddepositionprocessis however sensitive to disturbances and thus requires continuous monitoring and adjustments.Inthis work a 3D scanning system is described forautomaticin-processcontrolof thedeposition. The goal is to obtain a flat surface for each deposited layerinorder to ensure stabledeposition. The deviationsinthe layer height are compensated by controlling thewirefeed rate. The system is tested throughdepositionof small cylindrical bosses and the results show that the proposedcontrolapproach is suitable forautomaticdepositionof such structures. The material consideredinthis paper is Ti-6Al-4V deposited on plates of same material. The paper presents the equipment and thecontrolstrategy and discusses practical issues regarding thesensorused.

  • 46.
    Heralic, Almir
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    Dep of signal and systems, Chalmers.
    Height control of laser metal-wire deposition based on iterative learning control and 3D scanning2012In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 50, no 9, p. 1230-1241Article in journal (Refereed)
    Abstract [en]

    Laser Metal-wire Deposition is an additive manufacturing technique for solid freeform fabrication of fully dense metal structures. The technique is based on robotized laser welding and wire filler material, and the structures are built up layer by layer. The deposition process is, however, sensitive to disturbances and thus requires continuous monitoring and adjustments. In this work a 3D scanning system is developed and integrated with the robot control system for automatic in-process control of the deposition. The goal is to ensure stable deposition, by means of choosing a correct offset of the robot in the vertical direction, and obtaining a flat surface, for each deposited layer. The deviations in the layer height are compensated by controlling the wire feed rate on next deposition layer, based on the 3D scanned data, by means of iterative learning control. The system is tested through deposition of bosses, which is expected to be a typical application for this technique in the manufacture of jet engine components. The results show that iterative learning control including 3D scanning is a suitable method for automatic deposition of such structures. This paper presents the equipment, the control strategy and demonstrates the proposed approach with practical experiments.

  • 47.
    Heralic, Almir
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Dep of signal and systems, Chalmers.
    Towards stable high-speed metal-wire deposition, Part II: Automatic deposition using feedback controlArticle in journal (Refereed)
  • 48.
    Heralic, Almir
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Ottosson, Mattias
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    Dep of signal and systems, Chalmers.
    Automation of laser metal deposition for the manufacture of fully dense structures2011In: 4th International Swedish Production Symposium, SPS11: 3-4 May, Lund, Sverige / [ed] Jan-Eric Ståhl, Swedish Productio Academy , 2011, p. 219-227Conference paper (Refereed)
  • 49.
    Heralic, Almir
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Ottosson, Mattias
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Norlander, Torbjörn
    Volvo Aero Coorporation.
    Geometry control of laser metal deposition for the manufacture of complex structures in the aero industry2011In: 20th International Society for Airbreathing Engines Conference, ISABE 2011: September 12-16, 2011 Gothenburg, 2011, p. 1666-1674Conference paper (Refereed)
  • 50.
    Heras Aguilar, Sergio
    University West, Department of Engineering Science, Division of Production System.
    Comparison and visualization of robot program modifications: Applied on ABB industrial robots at Volvo Cars Corporation2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Volvo Cars Corporation creates robot programs off-line for all new robot implementations for virtual commissioning. These virtually created robot programs are then downloaded to the real robot, after the installation has been carried out, to be tested before they are fully operational. These tests are spanned from robot installation until full production, adjusting the robot programme according to Volvo Cars specification and correcting errors that the robot program may have. Changes of the robot programs will be saved each time it is modified, generating a series of backups for each robot until the robot is correctly adjusted along all the steps of the process. To improve the offline programming there is a necessity for visualize the modifications made during the physical robot commissioning. The objective of this thesis is to identify, categorise, quantify and visualize modifications between each different backup of a robot. A software application has been developed using Microsoft Visual Studio using C#. The application is designed in windows for different types of data. It enables the user to compare two robot programs (two different backup programs from the tests) from one robot and see the result between them graphically. The graphs are designed interactively so that the user can filter the information to see the desired data from the robot programs comparison. Key performance indicators (KPIs) has been specified for RobTargets and Procedures according to Volvo Cars Corporation requests. These KPIs are implemented and visualised in a graphical representation.

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