What Machine Vision Tool is Right for Your Application?

Machine vision is an inherent terminology in factory automation but selecting the most efficient and cost-effective vision product for your project or application can be tricky.

We can see machine vision from many angles of view, for example market segment and application or image processing deliver different perspectives. In this article I will focus on the “sensing element” itself, which scan your application.

The sensing element is a product which observes the application, analyzes it and forwards an evaluation. PC is a part of machine vision that can be embedded with the imager or separated like the controller. We could take many different approaches, but let’s look at the project according to the complexity of the application. The basic machine vision hardware comparison is

  1. smart sensors
  2. smart cameras
  3. vision systems

Each of these products are used in a different way and they fit different applications, but what do they all have in common? They must have components like an imager, lens, lighting, SW, processor and output HW. All major manufacturing companies, regardless of their focus or market segment, use these products, but what purpose and under what circumstances are they used?

Smart Sensors

Smart sensors are dedicated to detecting basic machine vision applications. There are hundreds of different types on the market and they must quickly provide standard performance in machine vision. Don’t make me wrong, this is not necessarily a negative. These sensors are used for simple applications. You do not want to wait seconds to detect QR code; you need a response time in milliseconds. Smart sensors typically include basic functions like:

  • data matrix, barcode and 2D code reading
  • presence of the object,
  • shape, color, thickness, distance

They are typically used in single purpose process and you cannot combine all the features.

Smart Cameras

Smart cameras are used in more complex projects. They provide all the function of smart sensors, but with more complex functions like:

  • find and check object
  • blob detection
  • edge detection
  • metrology
  • robot navigation
  • sorting
  • pattern recognition
  • complex optical character recognition

Due to their complexity, you can use them to find products with higher resolution , however it is not a requirement. Smart cameras can combine more programs and can do parallel several functions together. Image processing is more sophisticated, and limits may occur in processing speed, because of embedded PC.

Vision Systems

Typically, machine vision systems are used in applications where a smart camera is not enough.

Vision system consists of industrial cameras, controller, separated lighting and lens system, and it is therefore important to have knowledge of different types of lighting and lenses. Industrial cameras provide resolution from VGA up to 30Mpxl and they are easy connected to controller.

Vision systems are highly flexible systems. They provide all the functions from smart sensors and cameras. They bring complexity as well as flexibility. With a vision system, you are not limited by resolution or speed. Thanks to the controller, you have dedicated and incomparable processing power which provides multi-speed acceleration.

And the most important information at the end. How does it look with pricing?

You can be sure that smart sensor is the most inexpensive solution. Basic pricing is in the range of $500 – $1500. Smart cameras can cost $2000 – $5000, while a vision system cost would start closer to $6000. It may look like an easy calculation, but you need to take into consideration the complexity of your project to determine which is best for you.

Pros Cons Cost
Smart sensor
    • Easy integration
    • Simple configuration
    • Included lightning and lenses
    • Limited functions
    • Closed SW
    • Limited programs/memory
$
Smart camera
    • Combine more programs together
    • Available functions
    • Limited resolution
    • Slower speed due to embedded PC
$$
Vision system
    • Connect more cameras(up to 8)
    • Open SW
    • Different resolution options
    • Requires skilled machine vision specialist
    • Requires knowledge of lightning and lenses
    • Increased integration time
$$$

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What’s So Smart About a Smart Camera?

Smart “things” are coming into the consumer market daily. If one Googles “Smart – Anything” they are sure to come up with pages of unique products which promise to make life easier. No doubt, there was a marketing consortium somewhere that chose to use the word “smart” to describe a device which includes many and variable features. The smart camera is a great example of one such product where its name only leads to more confusion due to the relative and ambiguous term used to summarize a large list of features. A smart camera, used in many manufacturing processes and applications, is essentially a more intuitive, all-in-one, plug-and-play, mid-level technology camera.

OK, so maybe the marketing consortium is on to something. “Smart” does indicate a lot of features in a simple, single word, but it is important to determine if those smart features translate into benefits that help solve problems. If a smart camera is really smart it should include the following list of benefits:

  • Intuitive: To say it is easy to use just doesn’t cut it. To say it is easy for a vision engineer to use doesn’t mean that it is easy for an operator, a controls engineer, production engineer, etc. The camera should allow someone who has basic vision knowledge and minimal vision experience to select tools (logically named) and solve general applications without having to consult a manufacturer for a 2 day on-site visit for training and deployment.
  • All-In-One: The camera should house the whole package. This includes the software, manuals, network connections, etc. If the camera requires an external device like a laptop or an external switch to drive it, then it doesn’t qualify as smart.
  • Plug-and-play: Quick set up and deployment is the key. If the camera requires days of training and consultation just to get it up and running, then it’s not smart.
  • Relative technology: Smart cameras don’t necessarily need to have the highest end resolution, memory, or processing speed. These specs simply need to be robust enough to address the application. The best way to determine that is by conducting a feasibility study along with the manufacturer to make sure you are not paying for technology that won’t be needed or used.

Ultimately, a lot of things can be described as “smart”, but if you can make an effort to investigate what smart actually means, it’s a whole lot easier to eliminate the “gotchas” that tend to pop up at the most inopportune times.

Note: As with any vision application, the most important things to consider are lighting, lenses and fixtures. I have heard vision gurus say those three things are more critical than the camera itself.