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In the world of manufacturing, solution offerings are abundant. Yet for all of the effort in offering, most solutions rarely deliver the expected results. Machine Vision solutions walk a fine line along a very dangerous cliff of failure. For most facilities, machine vision is a “side job.” Machine Vision solutions can quickly become complicated or complex. Hardware selection, software packages, and program methodologies each carries its own vast and rapidly evolving choices. Selecting and integrating the best solution for a specific application can become difficult and uncertain. For this reason, one must approach each application as a practical vision engineer. Practical vision engineers take time to understand the scope of the application and ask three fundamental questions that lead them to choose one of three tiers of machine vision solutions.
Tier 1–Basic Sensor Technology
The first question a practical vision engineer asks is, “Does the application actually need a camera?” Yes, cameras can do presence/absence inspection, measurement, and checks for proper color but so can basic sensors. The advancement in sensor technology has made it possible for simple inspections to be robust and cost-effective. Very little reason exists to add smart camera if the inspection requirements are merely to check between two or even three colors. Sensors can do that for a fraction of the cost. Measurement applications can be solved by a laser sensor or simple photo-eye. In fact, I spoke with a customer who had an application that required certain work be performed on the product based on the measurement of a buss bar. The common solution discussed was to use a smart camera. However, after a quick discussion about the scope of the inspection, a much more cost effective and robust solution was discovered. Placing multiple photo-eyes in a row based on the different lengths of the buss bars and using the PLC to determine which length was present provided the same information with much less hardware and programming. There was no need for lighting or a large field of view or verifying of a vision program. It just worked. A practical vision engineer looks for reasons not to use a camera. An approach like this can produce a variety of successful out-of-the-box solutions. Tier 1 solutions look for the opportunity to utilize the ease-of-use and low-cost sensors for the given scope of an inspection.
"One must approach each application as a practical vision engineer. Practical vision engineers take time to understand the scope of the application and ask three fundamental questions that lead them to choose one of three tiers of machine vision solutions"
Tier 2–Simple Vision Integration
The second question a practical vision engineer asks is, “How many variations are there?” If the application is for a part with multiple components, and various features, and/or multiple colors then using a smart camera is a better choice. Smart cameras offer much more flexibility that can accommodate these types of variances. They key is to keep the inspection simple. Robust fixturing and strong tool selection are the best ways to build and deploy a successful vision application. Edge, blob, or histogram vision tools are extremely useful because they are fast and can easily be made binary. They are easily setup and maintained. Growing and adapting vision systems are easily performed with smart cameras. Because of this, it is important to ask a follow-up question, “What is the potential scope creep?” Scope creep refers to changes or uncontrolled growth in a project’s definition, after the project’s final design approval has been defined. Scope creep can be created from variables such as the change of a supplier or an additional inspection the customer might want to add. Smart cameras are scalable. Smart cameras are easily modified with different lens or lighting. This is not limited to just 2D camera. Today 3D vision has become more versatile and economical. Some systems have even developed configuration wizards that will walk the user through the setup. The idea is always to keep it simple and robust. This holds true even for legacy vision systems already existing on a machine. I once experienced a customer who wanted to add a new camera and another inspection to an existing machine. As the discussion about the scope of the inspection progressed, we discovered the simplest solution was to just add another light to the existing inspection and use the light only when certain product is running. In another case, a customer wanted to install a 3D vision system to check if a box was empty. While the 3D system would work well, the simpler vision solution was to use a low-resolution camera to see the dark parts in the white box. This inspection merely required a basic histogram analysis tool. A practical vision engineer looks for the simplest solution that exists within the scope of the project. Tier 2 solution looks for the opportunity to integrate a simple vision application using simple vision algorithm tools to successfully and robustly solve the vision system application.
Tier 3–Advance Vision Systems
The third question a practical vision engineer asks is, “Am I in over my head?” Most of the tier 1 and 2 applications can be easily and successfully deployed with common vision knowledge. Tier 3 applications, however, require expert level knowledge and expertise in algorithms, technology and integration. Applications including scopes requiring high-level precision, extensive inspection and/or high speed are in this tier. In addition, applications that require rigid quality control specification also could fall into tier 3. This applies both to 2D and 3D vision systems. Solutions in tier 3 do not necessarily have to be PC-based. Smart cameras, in many cases, can give highly accurate and repeatable results. It is all about the science required in selecting the hardware components and applying very deliberate vision algorithm tools to successfully solution the application requirements. One concern with such elaborate vision systems is that they will be difficult to maintain. That is not necessarily the case. A robust vision system simply is well planned to consider and address all the challenges possible before the building process begins. Therefore, it is imperative to be crystal-clear on the scope of the application before reaching outside of your organization for help. A practical vision engineer will work closely with the selected integrator to build a successful application. Tier 3 solution utilizes the experts in advance vision systems.
A practical vision engineer is someone who asks the questions, the right questions, and all of the questions. Striving to understand the scope of the given application and build the most successful solution. The solution might be using basic sensors technology, simple vision integration, or advance vision systems. Lean and effective solutions are the path to becoming a successful and practical vision engineer.