The invention relates to a method for computer-implemented determination of sensor positions in a simulated process of an automation system.
The complexity of sensors in automation systems, such as manufacturing plants, is increasing. Particularly, the geometric dimensions and sensing restrictions of sensors have increased by employing camera systems or by using combined sensors to enable sensor fusion. Hence, for processes of an automation system simulated on a computer, there is a need to analyze those processes to determine whether the placement of corresponding sensors for performing a predetermined sensor task is at all possible within the respective process.
In view of the foregoing, it is therefore an object of the invention to provide a computer-implemented method that provides the ability to determine possible sensor positions for performing a sensing task in a simulated process of an automation system.
In the method in accordance with the invention, the simulated process of the automation system includes a digital process description of an automation task to be executed by a number of components of the automation system. In a preferred embodiment, the number of components comprises at least one robot. The process description includes a movement specification describing the movement of the number of components during the execution of the automation task. The movement specification may be provided based on a kinematic model of the number of components. Such movement specifications are known per se from the prior art. The method of the invention also processes a digital sensing description, where the sensing description defines a sensing task to be performed by a sensor (e.g., the detection of a specific object at a predetermined position within an automation cell) as well as a number of sensor parameters of the sensor means. For example, the sensor may comprise at least one camera for detecting one or more objects handled by the number of components. The number of sensor parameters comprises one or more sensing constraints of the sensor. A sensing constraint may be described by a condition that has to be fulfilled so that the sensing task can be performed. In the case of a camera, a sensing constraint may refer to the focal length of the camera where the camera has to be placed within a spherical shell around the object to be detected where the spherical shell Includes as a radius the focal length of the camera.
In a step a) of the method in accordance with the invention, a placement volume based on the movement specification is determined, where the placement volume lies within a predetermined area surrounding the number of components. This area may, e.g., be the volume of an automation cell of an automation system where the simulated process is executed within the automation cell. Furthermore, the placement volume does not overlap with the number of components and any other object (excluding the sensor) during the execution of the automation task.
In a step b) of the method in accordance with the invention, a sensor arrangement volume is determined, where the sensor arrangement volume defines a volume of sensor positions of the sensor. The sensor positions may, e.g., be defined based on the center of gravity of the sensor. The sensor arrangement volume is defined such that the sensor volume of the sensor lies at each sensor position within the sensor arrangement volume completely inside the placement volume and that the sensing task can be performed during the execution of the automation task at each sensor position within the sensor arrangement volume by the sensor with respect to the number of sensing constraints.
The method of the invention provides a straight forward computer-implemented method for determining possible sensor positions by calculating a volume not covered by the components of the automation system. Hence, it is guaranteed that the volume of the sensor does not interfere with the components of the automation system. Furthermore, the method considers sensing constraints given for the respective sensor to ensure that the sensing task can indeed be performed at a respective sensor position. Preferably, a warning is output via a user interface and particularly via a visual user interface in cases in which a sensor arrangement volume cannot be identified by the method of the invention.
In a preferred embodiment of the invention, at least one sensor position is identified within the sensor arrangement volume based on one or more optimization criteria. Those optimization criteria may be defined differently depending on the circumstances. For example, an optimization criterion may be a short cable length connecting the sensor with a plug or an optimization criterion may refer to a good accessibility of the position for mounting the sensor. In accordance with the presently contemplated embodiment, preferred sensor positions within the sensor arrangement volume are determined based on desired criteria.
In a particularly preferred embodiment, the sensor arrangement volume and/or the at least one sensor position identified by optimization criteria are output via a user interface. Particularly, this information is shown on a visual user interface, e.g., a display. Preferably, the visualized sensor arrangement volume and/or the at least one visualized sensor position are highlighted within a picture showing the relevant components of the automation system.
In a preferred embodiment of the invention, the determination of the sensor arrangement volume based on the above step b) comprises the following sub-steps:
determining an intermediate volume defining a volume of sensor positions of the sensor, where at each sensor position within the intermediate volume the sensing task can be performed by the sensor with respect to the number of sensing constraints without considering the placement volume;
determining the intersection between the intermediate volume and the placement volume; and
determining as the sensor arrangement volume that area within the intersection where the sensing task can be performed by the sensor with respect to the number of sensing constraints considering the placement volume (e.g., no obstructions in the detection area of the sensor during sensing) and where the sensor volume lies completely within the placement volume.
In another particularly preferred embodiment, additional steps are performed in cases in which a sensor arrangement volume cannot be identified in step b). Those steps enable the determination of sensor positions under the assumption that the sensor is movable. The embodiment comprises the following:
associating with the sensor a mechanical mechanism for moving the sensor, where the sensor and the mechanical mechanism form a movable sensor platform, where an operation time is assigned to the movable sensor platform, where the operation time is the time for moving the sensor from a first position (e.g., an idle position) to a second position that is a sensing position, performing the sensing task by the sensor in the sensing position and moving the sensor back to the idle position;
determining a movement volume of the movable sensor platform, where the movement volume is the volume covered by the movable sensor platform during the operation time of the movable sensor platform; and
dividing the automation task into a plurality of subsequent sub-tasks, where each sub-task is associated with a sub-task time needed to execute the sub-task.
For each sub--task having a sub-task time greater than or equal to the operation time of the movable sensor platform, the following sub-steps are performed:
determining for the respective sub-task a sub-task placement volume based on that part of the movement specification which describes the movement of the number of components during the execution of the respective sub-task, where the sub-task placement volume lies within the predetermined area surrounding the number of components and where the sub-task placement volume does not overlap with the number of components and any other object (excluding the sensor platform) during the execution of the respective sub-task; and
determining one or more mount positions of the movable sensor platform, where at each mount position the movement volume of the movable sensor platform lies completely within the respective sub-task placement volume and the sensing task can be performed during the execution of the respective sub-task by the sensor with respect to the number of sensing constraints.
By considering the movement of the sensor by a mechanical mechanism and by dividing an automation task in sub tasks, valid sensor positions in the form of mount positions of a movable sensor platform may be found in accordance with the presently contemplated embodiment.
In an alternative preferred version of the above embodiment, at least one mount position is identified within the determined one or more mount positions based on one or more optimization criteria. The optimization criteria may be the same criteria as described above, e.g., the optimization criteria may refer to a short cable length or to a good accessibility of the sensor platform.
In another preferred embodiment, the one or more determined mount positions for one or more sub-tasks and/or the at least one identified mount position determined based on one or more optimization criteria are output via a user interface. Particularly, those positions are visualized on a visual user interface.
The method in accordance with the disclosed embodiments of the invention may be applied to simulated processes of different automation systems. Particularly, the automation system may be a production system for producing or manufacturing a product, e.g., an assembly line. Furthermore, the automation system may be a packaging plant or a logistic system.
It is also an object of the invention to provide an apparatus for computer-implemented determination of sensor positions in a simulated process of an automation system, where the apparatus is configured to perform the method in accordance with the disclosed embodiments of the invention or the method of one or more preferred embodiments of the invention. In other words, the apparatus comprises a computing means or computer including a processor for performing the method in accordance with the disclosed embodiments of the invention or the method in accordance with one or more preferred embodiments of the invention.
It is also an object of the invention to provide a computer program product with program code, which is stored on a machine-readable carrier, for performing the method in accordance with the disclosed embodiments of the invention or the method in accordance with one or more preferred embodiments of the invention when the program code is executed by a processor on a computer.
It is also an object of the invention to provide a computer program with program code for performing the method in accordance with the invention or the method in accordance with one or more preferred embodiments of the invention when the program code is executed by a processor on a computer.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
In the following, embodiments of the invention will be de scribed in detail with respect to the accompanying drawings, in which:
A first embodiment of the invention will be described based on a simulated process in an automation system where the simulated process refers to an automation task handled by a robot. The automation task is illustrated in
In accordance with the first embodiment, a suitable position of a sensor 3 in the form of a camera shall be determined so that the object 4 can be detected in position B and the sensor 3 does not interfere with the robot 1. In order to determine such a position, a computer program is executed on a computer that uses digital data describing the simulated process.
With reference to
Based on the above input data, the first embodiment of the invention performs step S1 of
The determination of the placement volume PV is illustrated in
After having calculated the placement volume PV, the method of
In order to calculate the sensor arrangement volume SAV, an intermediate volume IV is determined. This is illustrated in
Optionally, the additional step S3 shown in
In cases in which no positions PO can be found by the method of
The steps shown in
As illustrated in
A digital description of the sensor platform SEP including the idle position and the sensing position as well as an operation time OT is used as input data in step S4 of
In step S4 of
This movement volume MV is shown in
Those sub-tasks STi having a sub-task time STTi greater than or equal to the operation time OT are processed in step S6. In this step, a sub-task placement volume SPVi is determined for the respective sub-task based on that part of the movement specification MS that describes the movement of the robots 1 and the conveyor belt 2 during the execution of the respective sub-task. The sub-task placement volume is the volume that does not overlap with the robots 1 and the conveyor belt 2 and any other object (excluding the sensor platform) during the execution of the respective sub-task STi.
After having determined the respective sub-task volumes SPVi, a search for mount positions MP of the mechanical mechanism 7 at the ceiling 8 is performed in step S7. In a respective mount position, the movement volume MV of the movable sensor platform lies completely within the respective sub-task placement volume SPVi and the sensing task can be performed during the execution of the respective sub-task STi by the sensor 3 with respect to the sensing constraints CO. The search for the mount position can be performed by analyzing different mount positions to evaluate whether the sensing task can be performed at the respective mount position. This step of analyzing respective mount positions uses the same methods as the determination of the sensor arrangement volume described with respect to the first embodiment. The mount positions found after having performed step S7 are designated as MP in
The disclosed embodiments of the invention as described in the foregoing has several advantages. Particularly, a powerful decision-making model is provided that incorporates the domain knowledge of experts in a formalized way by describing a general technical method for placing sensors. The disclosed embodiments of the invention are implemented as a computer program and enables non-experts to identify possible sensor positions for a sensing task within an automation system by running the computer program.
The formalized determination of sensor locations leads to a repeatable, exact and correct solution for performing a sensing task. The proposed formalization includes technical features such as the observable state of an automation system and explicit parameters of the sensor itself, such as the focal length or the acquisition field of a camera. Furthermore, the dynamic behavior of the components of the automation system is taken into account by determining swept volumes covered by the components. The method of the invention can hardly be reproduced in such accuracy by manual engineering. Furthermore, in a preferred embodiment, it is also possible to consider the scenario of a movable sensor platform in case those static sensor locations for the sensing task cannot be found.
Thus, while there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the methods described and the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
This is a U.S. national stage of application No. PCT/EP2018/079277 filed 25 Oct. 2018.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/079277 | 10/25/2018 | WO | 00 |