Demonstrator shows power of OPC Machine Vision

Suprateek Banerjee, of VDMA Robotics and Automation, updates on the progress made on OPC UA for Machine Vision, the machine communication standard


embers of the VDMA OPC Machine Vision initiative, together with the OPC UA Foundation,

have developed a hardware demonstrator that includes a practical implementation of the OPC UA for Machine Vision (OPC MV) Part 1 companion specification. ‘From the point of view of automation

technology and factory IT, this specification represents enormous progress. Image processing systems are among the most complex components in machine building. Teir integration is considerably simplified by manufacturer-independent uniform methods for control and data administration,’ said Dr Peter Waszkewitz, software project manager at Robert Bosch Manufacturing Solutions, and a member of the core working group. OPC MV Part 1 describes an abstraction

of the generic image processing system, i.e. a representation of a digital twin of the system. It handles the administration of recipes, configurations and results in a standardised way, while the contents remain manufacturer-specific and are treated as a black box. Te demonstrator establishes an infrastructure layer that enables a simplified and uniform integration of all possible image processing systems into higher-level IT production systems (such as PLC, Scada, MES, ERP, Cloud). It demonstrates the generalised control of a vision system and abstracts the necessary behaviour via the concept of a state machine.

Te VDMA Machine Vision initiative Open Platform Communications Unified Architecture (OPC UA) is a vendor- and platform-independent machine-to-machine communication technology, recommended by the German Industry 4.0 initiative and other international consortiums, such as | @imveurope

the Industrial Internet Consortium (IIC), to implement Industry 4.0. Te specification of OPC UA can be divided into two areas: the basis specification and companion specifications. Te basis specification describes ‘how’ data can be transferred, while the companion specifications describe ‘what’ information and data are transferred. Te OPC Foundation is responsible for

the development of the basis specification. Sector-specific companion specifications are developed in working groups, usually organised by trade associations. Te VDMA is a key player in the Industry 4.0 initiative.

Working towards Part 2 In Part 1 of the specification, the behaviour of a machine vision system is described and depicted with the help of black boxes. It specifies the way a machine vision system functions, rather than standardising the data in those black boxes. For future parts of the specification, the proprietary input and output data black boxes need to be broken down and substituted with standardised information structures and semantics. Tis follows the idea of implementing information model structures derived from OPC UA DI (Device Integration, Part 100), as OPC Robotics has already done in Part 1 of the OPC Robotics companion specification. It therefore ensures the idea of cross domain interoperability, so that machine vision systems can talk to robots and vice versa, and at a later stage to all kinds of devices. In September last year, there was a clear

consensus by the core working group and various other stakeholders, that for Part 2 of the specification the topics of interest should be asset management, condition monitoring and result data standardisation. With this aim in mind, in January the OPC

Machine Vision core working group kicked off the work for Part 2 of the specification. Unfortunately, shortly thereafter, the world was hit by the pandemic. As an international working group, it was difficult to meet physically, but we continued working and met digitally. Te core working group comprises experts

from Vitronic, Asentics, Robert Bosch Manufacturing Solutions, MVTec Software, Peer Group, Stemmer Imaging, Silicon Software, Isra Vision, Kolektor, Matrix Vision, Kuka and Beckhoff Automation. In order to be able to describe a machine

vision system at the component and sub- component level, the working group listed several user stories describing the kind of information different user groups would need to know about a vision system and its components. Tis resulted in filtering the asset management and condition monitoring parameters outlined for the components of a vision system. Te OPC Machine Vision core working

group is in the final stages of this filtering process. Te next step is to start on the

‘Te working group is in the final stages of filtering the asset management and condition monitoring parameters outlined for the components of a vision system’

information model for Part 2. After that, the group will implement the model and include the same information in the existing OPC machine vision demonstrator. A separate work package has been

dedicated to standardising the result data generated by a vision system. As this is a topic that multiple working groups are interested in, the OPC MV core working group is talking with groups involved in other standardisation initiatives, such as OPC UA for Tightening Systems, OPC UA for Grippers, and OPC UA for Robotics. Te VDMA Robotics and Automation

association is trying to come up with standardised result metadata that can be customised by all stakeholders, as the first step towards standardising branch-specific result data. O

The OPC UA for Machine Vision Part 1 companion specification can be downloaded here: viewer/-/v2article/render/37795049


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