| 21. |
- Bergagård, Patrik, 1984, et al.
(författare)
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Derivation of placement transitions for offline calculation of restart states
- 2013
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 1946-0759 .- 1946-0740.
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Konferensbidrag (refereegranskat)abstract
- This paper presents a preprocess to an existing method for offline calculation of restart states for manufacturing systems modeled by operations. In the existing method, placement transitions are used to model restart in restart states from potential error states, and supervisory control theory is used to calculate which of these transitions are valid. With the proposed preprocess, the precedence andthe alternative dependencies between the operations are exploited in order to reduce the number of such placement transitions which are required in the model used by theexisting method. With such a reduced model, the valid restart states for larger and more complex systems can be calculated.
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| 22. |
- Bergagård, Patrik, 1984, et al.
(författare)
-
Modeling and automatic calculation of restart states for an industrial windscreen mounting station
- 2015
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Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 48:3, s. 1030-1036
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Konferensbidrag (refereegranskat)abstract
- The production in an automated manufacturing system will not always progress as intended. A wide variety of possible faults may cause errors that lead to an unsynchronization between the control system and the physical system that consequently lead to production stoppages. The common industrial practice to deal with such non-intended progress is to extend the control system with tailor-made solutions to account for errors. This extension is both time consuming and there is no guarantee that all relevant errors are handled.This paper models the control system to enable automatic derivation of restart states applied to an existing station for automatic mounting of windscreens onto car bodies. These restart states are states in the control system where it is correct to resynchronize the control and the physical systems so that the automated production can be resumed. This aids the preparation phase by letting the developer focus on modeling the nominal production and on specifying (un-)desired behavior during the restarted production, and then automatically retrieve the restart states for all control states. The online restart process is then reduced to a semi-automatic process where an operator can be supported with instructions for how to correctly resynchronize the control and the physical systems in a selected restart state.
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| 23. |
- Bergagård, Patrik, 1984, et al.
(författare)
-
On restart of automated manufacturing systems using restart states
- 2015
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Ingår i: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. - 9781467381833 ; 2015-October, s. 166-167
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Konferensbidrag (refereegranskat)abstract
- Highly automated manufacturing systems have gained industrial popularity for their ability to combine high product volumes with high product quality. The high cost of investment in combination with many linked manufacturing systems in a factory, requires that the production runs smoothly with high utilization of the resources and that stoppages are avoided. One major reason for stoppages is the occurrence of errors. A wide variety of possible faults, such as badly fixated parts, broken actuators, and teething problems in the system, may cause errors that lead to an unsynchronization between the control system and the physical system that consequently lead to production stoppages [1,2]. The succeeding error recovery is often a complex and thereby time consuming process that typically requires operator involvement [3]. To plan for restart after errors already during the development of the system would therefore greatly support the online restart process and reduce the time the production is undesirably stopped. The common industrial practice to deal with such non-intended progress is to extend the control system with tailor-made solutions to account for foreseen errors [4,5]. This extension is both time consuming and there is no guarantee that all relevant errors are handled.
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| 24. |
- Bonafilia, Brian, et al.
(författare)
-
Robust manual control of a manufacturing system using supervisory control theory
- 2014
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 2405-8963 .- 1474-6670. - 9783902823625 ; 19, s. 748-753
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Konferensbidrag (refereegranskat)abstract
- There are many situations where manual intervention in automated systems, such as flexible manufacturing systems, is inevitable. Commonly the control of a manufacturing system is implemented in terms of operations, and sequences thereof, and these operations can typically be run manually. However, running the operations in arbitrary order may lead to situations such as blocking or collisions, from which it its hard or even impossible to recover or to resume automatic execution. This paper describes an implementation of an operator interface for robust manual control of a manufacturing system, where the operator is aided not to manually drive the system into a state that breaches the system requirements. Hence, blocking and collisions are avoided, and automatic mode can always be resumed. From a model of the manufacturing system based on self-contained operations, each of which is identified in terms of events with preconditions, a supervisor is calculated by use of the Supervisory Control Theory framework. From this supervisor additional preconditions are extracted for each operation. The operations with the extended preconditions are then ported to an operator interface which allows manual control of the production cell by dynamically guiding the operator to only those operations for which the extended preconditions are satisfied.
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| 25. |
- Dahl, Martin, 1984, et al.
(författare)
-
Automatic modeling and simulation of robot program behavior in integrated virtual preparation and commissioning
- 2017
-
Ingår i: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 11, s. 284-291
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method where the behavior of a robot cell is automatically modeled based on existing robot programs and a simulation model of the cell. Robot programs from the shop floor are uploaded into a virtual manufacturing tool, and a formal model is then generated from the robot programs. Then, control logic is automatically calculated, and the fastest possible execution order is found by using the generated model to formulate an optimization problem. The result is continuously analyzed and validated by simulation in the virtual manufacturing tool.
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| 26. |
- Dahl, Martin, 1984, et al.
(författare)
-
Control components for Collaborative and Intelligent Automation Systems
- 2019
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Ingår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 1946-0759 .- 1946-0740. ; 2019-September, s. 378-384
-
Konferensbidrag (refereegranskat)abstract
- Collaborative and intelligent automation systems need intelligent control systems. Some of this intelligence exist on a per-component basis in the form of vision, sensing, motion, and path planning algorithms. To fully take advantage of this intelligence, also the coordination of subsystems need to exhibit intelligence. While there exist middleware solutions that eases communication, development, and reuse of such subsystems, for example the Robot Operating System (ROS), good coordination also requires knowledge about how control is supposed to be performed, as well as expected behavior of the subsystems. This paper introduces lightweight components that wraps ROS2 nodes into composable control components from which an intelligent control system can be built. The ideas are implemented on a use case involving collaborative robots with on-line path planning, intelligent tools, and human operators.
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| 27. |
- Dahl, Martin, 1984, et al.
(författare)
-
Guard extraction for modeling and control of a collaborative assembly station
- 2020
-
Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 53:4, s. 223-228
-
Konferensbidrag (refereegranskat)abstract
- A transition system represented by guards and actions can be amended by new guards computed in order to satisfy some specification. If the transition system is the result of composing smaller state machines, guard extraction can be used to put the new guards onto the guards the original state machines. Planning and verification can then be performed directly on the system with additional guards. In this paper we discuss the benefits of applying guard extraction as part of the modeling work in a modular control architecture, where reusable resources are composed using specifications. We show with an example from the development of an industrial demonstrator that even if the specification language is limited to invariant propositions, in practice many common safety specifications can be expressed when combined with a notion of which transitions are allowed to be restricted.
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| 28. |
- Dahl, Martin, 1984, et al.
(författare)
-
Integrated Virtual Preparation and Commissioning: supporting formal methods during automation systems development
- 2016
-
Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 49:12, s. 1939-1944
-
Konferensbidrag (refereegranskat)abstract
- Virtual commissioning – the development and validation of industrial control systems against a simulation model – is attracting interest in the automotive industry. The main motivation for its use is that control systems can start to be integrated and tested before the construction of the physical system. In addition to this, the ability to continuously test can lead to increased reliability and enables better coping with late changes. At the same time, using formal methods during production preparation and control system design promise similar benefits. Formal methods however, are not seeing the same surge in interest – they are rarely used in the automotive industry. In this paper a framework is proposed, Integrated Virtual Preparation and Commissioning, where virtual commissioning models are used as a base for preparation and control system implementation assisted by formal methods. The extensive use of simulation in virtual commissioning allows computation results from formal methods to be continuously validated by visual inspection and using existing analysis tools (e.g. collision detection methods). The framework is applied in a case study, where the combination of a simulation model and a formal model is used as an aid in generating operation sequences for validation during production preparation. The resulting formal model can be used to study the behavior of the production system before a control system has been implemented.
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| 29. |
- Dahl, Martin, 1984, et al.
(författare)
-
Interactive formal specification for efficient preparation of intelligent automation systems
- 2022
-
Ingår i: CIRP Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 38, s. 129-138
-
Tidskriftsartikel (refereegranskat)abstract
- The automation system of the future will consist of an increasing amount of complex resources, such as collaborative robots and/or autonomously roaming robots for material handling. To control these devices in an environment shared with human operators require state of the art computer perception and motion planning algorithms to be used as part of the automation system. This new type of intelligent automation system, where intelligent machines and learning algorithms are replacing more traditional automation solutions, requires new methods and workflows to keep up with the increase in complexity. This paper presents an interactive and iterative framework for solving some of these new challenges. The framework supports model-based control system preparation performed simultaneously to preparation of 3D geometries, positioning of robots, and tool design. The workflow enables an interactive preparation process, where new resources and constraints can be added to a live (real or simulated) automation system and control system failures can be analyzed in familiar tools for virtual preparation. Additionally, the paper describes how the integrated preparation process was applied to reconfiguring an industrial use case that includes a collaborative robot working side by side with a human operator, smart tools, and a vision system for localizing both work objects and tools.
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| 30. |
- Dahl, Martin, 1984, et al.
(författare)
-
Sequence Planner: A Framework for Control of Intelligent Automation Systems
- 2022
-
Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 12:11
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a framework that tackles the challenges met in the development of automation systems featuring collaborative robotics and other machines that have some degree of autonomy. These machines rely on online algorithms for both sensing and acting in order to achieve a very high level of flexibility. To take advantage of these new machines and algorithms, control systems must also be increasingly flexible. In this paper, we present a framework for control of this new class of intelligent automation systems called Sequence Planner (SP), which helps with control of both traditional automation equipment and machines with autonomy. To aid the complex task of developing automation control solutions, SP relies on supporting algorithms for control logic synthesis and online planning. SP has been implemented with plug-in support for the Robot Operating System (ROS) and applied to an industrial demonstrator. We present our findings on how SP performed as a control system for this demonstrator, where we show that it is an adequate approach to implement automation for a highly flexible single station system. As a standardized way of automating such systems is missing, we hope that our contribution will provide a foundation for how to develop intelligent automation systems.
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