| 1. |
- Bengtsson, Kristofer, 1979, et al.
(författare)
-
Relations Identification and Visualization for Sequence Planning and Automation Design
- 2010
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Ingår i: In Proc. IEEE Conference on Automation Science and Engineering, Toronto. - 9781424454471 ; , s. 841 - 848
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Konferensbidrag (refereegranskat)abstract
- The sequential behavior of a manufacturing system results from a number of constraints introduced both in product, manufacturing and control logic development. Sequence planning is therefore an important activity throughout the complete development process. This paper proposes a sequence planning approach using self-contained manufacturing operations that model actions and relevant execution conditions. These operations can have temporal relations with each other, due to execution constraints expressed by operation pre- post- and reset conditions. The operation relations can for example be parallel, sequence, arbitrary order, alternative or hierarchy. Based on a formal operation model, the relations among operations are identified and visualized with a graphical language called Sequences of Operations, SOP.
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| 2. |
- Bengtsson, Kristofer, 1979, et al.
(författare)
-
Sequence Planning Using Multiple and Coordinated Sequences of Operations
- 2012
-
Ingår i: IEEE Transactions on Automation Science and Engineering. - 1558-3783 .- 1545-5955. ; 9:2, s. 308-319
-
Tidskriftsartikel (refereegranskat)abstract
- The sequential behavior of a manufacturing system results from several constraints introduced during the product, manufacturing, and control logic development. This paper proposes methods and algorithms for automatically representing and visualizing this behavior from various perspectives throughout the development process. A new sequence planning approach is introduced that uses self-contained operations to model the activities and execution constraints. These operations can be represented and visualized from multiple perspectives using a graphical and formal language called Sequences of Operations (SOPs). The operations in a manufacturing system are related to each other in various ways, due to execution constraints expressed by operation pre- and post-conditions. These operation relations include parallel, sequence, arbitrary order, alternative, and hierarchy relations. Based on the SOP language, these relations are identified and visualized in various SOPs and sequences. A software tool, Sequence Planner, has been developed, for organizing the operations into SOPs that visualize only relevant operations and relations. Note to Practitioners-This paper proposes methods and algorithms for a new sequence planning approach in which sequences are automatically created based on the relations among operations instead of having to be manually constructed. Using various views, the sequences of operations related to, for example, part flow, robot operations, and operator tasks, can be visualized. The use of various views helps the user better understand the relations between cell control and mechanical design, and between product design and total system behavior.
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| 3. |
- Lennartson, Bengt, 1956, et al.
(författare)
-
Sequence Planning for Integrated Product, Process and Automation Design
- 2010
-
Ingår i: IEEE Transactions on Automation Science and Engineering. - 1558-3783 .- 1545-5955. ; 7:4, s. 791-802
-
Tidskriftsartikel (refereegranskat)abstract
- In order to obtain a unified information flow from early product design to final production, an integrated framework for product, process and automation design is presented. The framework is based on sequences of operations and includes a formal relation between product properties and process operations. This relation includes liaisons (interfaces) and precedence relations, where the precedence relations generate preconditions for the related process operations. From this information a set of sequences of operations (SOPs) is generated. A formal graphical language for hierarchical operations and SOPs is then introduced and defined based on automata extended with variables. Since the operations are self-contained they can be grouped and viewed from different angles, e. g., from a product or a resource perspective. These multiple views increase the interoperability between different engineering disciplines. A case study is performed on a car manufacturing cell, where the suggested modeling framework is shown to give comprehensible SOPs. Note to Practitioners-When designing an automation system, an important challenge is to specify in what sequence the different tasks, or operations, should be executed. This has become a problematic bottleneck in the automotive industry, especially for body-in-white manufacturing. The rising needs on manufacturing flexibility increases the complexity of the entire manufacturing system, as well as its control function, the sequence of operations. This paper proposes a new sequence planning approach, where sequences are viewed based on the relations among operations instead of manually constructing the sequence. By the use of different views the sequence of operations related to, e. g., the part flow, robot operations or operator tasks can be visualized. Different views help the user to easier understand the relation between different parts and components, as well as the total system behavior.
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| 4. |
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| 5. |
- Berlin, Jonas, et al.
(författare)
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Trajectory Generation for Mobile Robots in a Dynamic Environment using Nonlinear Model Predictive Control
- 2021
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Ingår i: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. ; 2021-August, s. 942-947
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an approach to collision-free, long-range trajectory generation for a mobile robot in an industrial environment with static and dynamic obstacles. For the long-range planning a visibility graph together with A is used to find a collision-free path with respect to the static obstacles. This path is used as a reference path to the trajectory planning algorithm that in addition handles dynamic obstacles while complying with the robot dynamics and constraints. A Nonlinear Model Predictive Control (NMPC) solver generates a collision-free trajectory by staying close to the initial path but at the same time obeying all constraints. The NMPC problem is solved efficiently by leveraging the new numerical optimization method Proximal Averaged Newton for Optimal Control (PANOC). The algorithm was evaluated by simulation in various environments and successfully generated feasible trajectories spanning hundreds of meters in a tractable time frame.
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| 6. |
- Bertilsson, Filip, et al.
(författare)
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Centralized versus Distributed Nonlinear Model Predictive Control for Online Robot Fleet Trajectory Planning
- 2022
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Ingår i: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. ; 2022-August, s. 701-706
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we formulate and evaluate a centralized vs. a distributed approach for online trajectory generation for a fleet of mobile robots in the presence of static and dynamic obstacles. Due to dynamic obstacles, the trajectories need to be updated online and this is formulated as a nonlinear model predictive control problem. We show that both centralized and distributed MPC solvers manage to generate smooth collision-free trajectories. The distributed approach is shown to scale to many robots very well. In contrast, the computational cost of the centralized approach increases with the number of robots. However, the trajectories generated by the distributed control approach have larger deviations than those generated by the centralized approach. The experiments suggest that the centralized method should be chosen with sufficient computation resource while the distributed approach is a viable alternative when the number of robots is considerable.
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| 7. |
- Byröd, Martin, 1980, et al.
(författare)
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Efficient Reachability Analysis on Modular Discrete-Event Systems using Binary Decision Diagrams
- 2006
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Ingår i: 8th International Workshop on Discrete Event Systems, WODES 2006; Ann Arbor, MI; United States; 10 July 2006 through 12 July 2006. - 1424400538 ; , s. 288-293
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Konferensbidrag (refereegranskat)abstract
- A well known strategy for handling the exponential complexity of modular discrete event systems is to represent the state space symbolically, using binary decision diagrams (BBDs). In this paper, key success factors in the design of efficient BDD-based reachability algorithms for synthesis and verification are discussed. It is also shown how the modular structure of a discrete event system (DES) can be utilized by taking advantage of the process communication graph and partitioning techniques. A reachability algorithm based on these principles is discussed and a proof of correctness for the algorithm is given.
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| 8. |
- Cengic, Goran, 1978, et al.
(författare)
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A Control Software Development Method Using IEC 61499 Function Blocks, Simulation and Formal Verification
- 2008
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Ingår i: Proceedings of the 17th IFAC World Congress. ; , s. 22-27
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Tidskriftsartikel (refereegranskat)abstract
- A new control software development method is presented. It uses IEC 61499 function blocks for control software programming and provides tools for simulation, execution, automatic model generation and formal verification of the control code during the development. Simulation and execution are supported by the same tool, the Fuber runtime environment. Formal modeling is done using extended finite automata (EFA) and an automatic model generation tool. Formal verification shows the behavior of the closed-loop system. i.e. when control code is executed against the model of the process. The model can use a non-deterministic execution control chart (ECC) in the process model block. The control code and the process model are expressed using the IEC 61499 language in order to avoid maintenance of the process model and control code in different languages, thus making it easier to use the formal verification in the control software development.
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| 9. |
- Cengic, Goran, 1978, et al.
(författare)
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A Framework for Component Based Distributed Control Software Development Using IEC 61499
- 2006
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Ingår i: Proceedings of the 2006 IEEE International Conference on Emerging Technology and Factory Automation, Sep 2006, Prague, Czech Republic.
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Tidskriftsartikel (refereegranskat)abstract
- A framework for component based distributed control software is proposed. The primary application for the framework is in distributed control systems. The framework proposes new software components, called automation components that can be hierarchically embedded to produce new components. Automation components are also combined to produce hierarchical component based applications. The framework is independent of the execution platform, however it is shown how an application that is developed using the framework can be executed using IEC 61499 platform. The validity of the framework is evaluated using an industrial example of a reconfigurable manufacturing cell.
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| 10. |
- Cengic, Goran, 1978, et al.
(författare)
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Definition of the Execution Model Used in the Fuber IEC 61499 Runtime Environment
- 2008
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Ingår i: Proceedings of the 6th IEEE International Conference on Industrial Informatics. - 1935-4576. ; , s. 301-306
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Tidskriftsartikel (refereegranskat)abstract
- The buffered sequential execution model (BSEM) for IEC 61499 function block applications is presented. Before the execution of the application the composite function blocks are flattened. The resulting application containing the basic and service interface function blocks is executed. The basic function blocks are put in the ready queue in the same order that they receive the input events, hence the word ldquosequentialrdquo in the name. Each basic function block keeps a queue of incoming events with their associated data, hence the word ldquobufferedrdquo in the name. Scheduling policy of the blocks is in the scheduling function while the execution policy of the received events is in the function block instance. The extended finite automata models suitable for formal verification of the proposed execution modelpsilas behavior are presented. The model may be analyzed using a discrete event systems tool called Supremica. The presented execution model is implemented in the Fuber runtime environment.
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