OPC Machine Vision
The OPC UA Companion Specification Machine Vision (in short OPC Machine Vision) provides a generic information model for all vision systems - from simple vision sensors to complex inspection systems.
Put simply, it defines the essence of any vision system that does not necessarily have to be a "machine" vision system. OPC Machine Vision is the accepted and officially supported OPC UA Companion Specification for vision systems by the OPC Foundation. See figure 1.
The scope is not only to complement or substitute existing interfaces between a vision system and its process environment by using OPC UA, but rather to create non- existing horizontal and vertical integration abilities to communicate relevant data to other authorized process participants, e.g. right up to the IT enterprise level. It is possible to have a gradual phase-in of OPC Machine Vision with coexisting other interfaces. The benefits are a shorter time to market by a simplified integration, a generic applicability and scalability and an improved customer perception due to defined and consistent semantics. Specific example: OPC Machine Vision enables Machine Vision to speak to the whole factory and beyond.
A vision system is any system that has the capability to record and process digital images or video streams, typically with the aim of extracting information from this data. The output of a vision system can be any image-based information like measurements, inspection results, process control data, robot guidance data, etc. See figure 2.
The basic concept of OPC Machune Vision is a subdivision into several parts. Part 1 includes the basis specification and describes an infrastructure layer which provides basic services in a generic way. From part 2, a vision skill layer is addressed which provides more specific vision services. See figure 3.
OPC Machine Vision, part 1
Part 1 describes an abstraction of the generic vision system, i.e. the representation of the so called "digital twin" of the system. It handles the management of recipes, configurations and results in a standardized way, whereas the contents stay vendor-specific and are treated as black boxes (1). It allows the control of a vision system in a generalized way, abstracting the necessary behavior via a state machine concept (2). See figure 4.
In future parts, the generic basic information model will shift to a more specific "skill-based” information model. Vision skills could include presence detection, completeness inspection, pose detection, etc. For this purpose, the proprietary input and output data black boxes will be broken down and substituted with standardized information structures and semantics.
The VDMA represents more than 3,200 member companies in the medium-sized mechanical and plant engineering sector. With 1.35 million employees in Germany and a turnover of 224 billion euros (2017), the sector is the largest industrial employer and one of the leading German branches of industry overall.
International G3 initiative to coordinate the development of globally adopted vision standards in cooperation of the American (AIA), Chinese (CMVU), European (VDMA and EMVA) and Japanese (JIIA) trade associations.
With over 600 member companies, the OPC Foundation is the world's leading community for interoperability solutions based on the OPC communication specifications. OPC is an interoperability framework for the secure, reliable and platform-independent exchange of information. OPC technology is widely used to integrate information in industrial automation and to enable data transfer from the smallest sensor to the enterprise IT level.
Core working group members:
See figure 5