Text / Lee Kielblock· Senior Application Engineer, Banner Engineering, USA The basic principle of visual sensing Basic elements of vision sensor applications Advantages of vision sensors Expanding range of applications The low cost and ease of use of vision sensors have attracted machine designers and process engineers to integrate them into a variety of applications that have relied on labor, multiple photoelectric sensors, or no inspection at all. Industrial applications of vision sensors include inspection, metrology, measurement, orientation, flaw detection and sorting. The following are just some application examples: Kitchen Aid Mixers,Cooking Steamer,Kitchen Aid Appliances,Home Appliances Ningbo Glory King Imp&Exp Co., Ltd. , https://www.gloryelectrical.com
Not long ago, engineers who designed quality control systems had to choose between several test options, none of which was entirely satisfactory. These options include expensive single-use vision systems, multi-array low-function photosensors, and human eye tests that are susceptible to fatigue and lack of concentration. However, today's state-of-the-art vision sensors combine the best of traditional methods with unprecedented speed, accuracy, size and cost advantages.
Figure 1 Vision sensor check tells the conveyor whether the correct part is being transferred
This article will compare the capabilities of various sensor options and demonstrate why visual sensing is the fastest growing segment of the industrial sensor market.
The photosensor includes a light sensing element, and the vision sensor has the ability to capture thousands of pixels of light from a single image. The clarity and detail of the image is usually measured in resolution and is expressed in number of pixels. Some of the vision sensors provided by Banner Engineering can capture 1.3 million pixels. Therefore, the sensor can "see" the delicate target image no matter how many meters or centimeters away from the target.
Figure 2 Broken pills in a blister pack found by a backlit vision sensor
After capturing the image, the vision sensor compares it to the reference image stored in memory for analysis. For example, if the vision sensor is set to identify the correct machine part with eight bolts inserted, or the part with the bolt misaligned. Furthermore, the visual sensor can make a determination no matter where the machine component is located in the field of view, whether or not the component is rotated within 360 degrees.
1. Lighting In vision sensor applications, lighting is the most important technical factor. The type and location of the light source is directly related to whether an image with the largest target background contrast can be created.
2. Tool Vision Sensors use algorithms to analyze the images they capture. A versatile, full-featured vision sensor provides a variety of algorithms (sometimes referred to as tools). Low-cost vision sensors may only include one tool, both of which have their own suitable applications.
Figure 3 In a pharmaceutical packaging application, the visual sensor identifies if the label is missing from the bottle.
The tool is divided into two basic categories: linear and flat. Both pay attention to the changes in the image, but the way is different.
(1) If the area to be watched is foreseeable, the linear tool is the best choice because the tool is faster and more accurate than the flat tool. For example, a vision sensor can use a linear tool (such as a cutting tool) to ensure that the vials that quickly pass through the assembly line are tightly closed.
(2) If the position of the target may change, such as a plastic bottle box that may lack one or more plastic bottles in a position in the box, the flat tool is most practical. The flat tool will check if the FCL is out of deviation from the standard.
Among the available inspection alternatives, namely vision systems, photoelectric sensors, manual inspections, and vision sensors, vision sensors are often the best choice for their accuracy, ease of use, rich functionality, and reasonable cost.
Figure 4 Trained, knowing how to monitor the mislabeling of sensors in the horizontal and vertical positions As the competition in various industries becomes more and more fierce, the profit margins become smaller and manufacturers can't afford the high scrap rate caused by the products. Therefore, in order to detect problems before they generate high costs, manufacturers are integrating inspection work into the entire manufacturing process.
1. The visual system and the visual sensor are more complex visual systems, which are a mature technology that can perform detailed automatic inspection. However, complexity and high cost hamper its use in many industries, often at prices ranging from $5,000 to $50,000. These complex vision systems require one or more cameras, custom software, and a computer. They often need to hire an external visual consultant to design, integrate, and install the system. Moreover, given the specificity of such systems, they cannot be easily adapted for other uses. These complex systems often require ongoing professional support.
While the need for complex vision systems still exists, the introduction of cheaper, easier-to-use vision sensors provides a more cost-effective solution for some industrial applications. In addition, because vision sensors are smaller and easier to use, manufacturers use vision solutions more frequently in inspection and verification applications. Vision sensors contribute to the quality improvement of factory automation and the improvement of production efficiency.
2. Comparison of Photoelectric Sensors and Vision Sensors Vision sensors give machine designers greater flexibility than photoelectric sensors. In the past, applications requiring multiple photosensors can now be tested with a single visual sensor. Vision sensors are able to inspect much larger areas and achieve better target position and direction flexibility. This has made vision sensors popular in applications that rely on only photoelectric sensors. Traditionally, these applications also require expensive accessories and precise motion control that ensures that the target object always appears in the same position and posture.
In addition, since the cost of a basic vision sensor is only equivalent to several photoelectric sensors with more expensive accessories, the price is no longer an issue.
Vision sensors offer unparalleled flexibility for application switching. For example, switching production processes (switching from a single serving of yogurt to an ice cream bucket) can take only a few seconds and can be done remotely. Additional test conditions can be easily added to this app.
3. Comparison of manual inspection and visual sensors Regardless of the progress of factory automation, many inspections are still done with the naked eye. However, in most applications, many of the advantages of vision sensors are beyond the manual inspection process. Vision sensors can operate at much higher speeds; perform repeated, multiple, consistent inspections at much lower cost.
â— At the car assembly plant, verify that the beads coated by the robot to the door frame are continuous and have the correct width.
â— In the bottling plant, verify that the cap is properly sealed, that the filling level is correct, and that no foreign matter has fallen into the bottle before the capping.
â— On the packaging line, be sure to attach the correct packaging label in the correct location.
â— In the pharmaceutical packaging line, check for ruptured or missing tablets in the blister pack of aspirin tablets.
◠In the metal stamping company, the stamped parts are inspected at speeds of more than 150 per minute – 13 times faster than manual inspection.
For visual sensors, this is an exciting time. Technology that once required a lot of expertise is now economical and easy to use. Future product development with this technology will continue this trend. The challenge now is how to make industries aware of the potential of vision sensors in all manufacturing areas, including quality control, measurement and inspection processes.