The hottest visual sensor ushers in rapid developm

Visual sensors usher in rapid development

Figure 1 Visual sensor verification tells whether the conveyor belt is conveying the correct parts

not long ago, engineers designing quality control systems had to choose among several inspection options, none of which was completely satisfactory. These options include expensive single purpose vision systems, multi array low-function photoelectric sensors, and human eye tests that are susceptible to fatigue and inattention. However, today's most advanced vision sensors are combining the best performance of traditional methods with unprecedented speed, accuracy, size and cost advantages

this article will compare the functions of various sensor options and prove why visual sensing has become the fastest-growing field in the industrial sensor market

basic principle of visual sensing

photoelectric sensor contains an optical sensing element, and the visual sensor has the ability to capture thousands of pixels of light from a whole image. The clarity and fineness of an image are usually measured by resolution, expressed in the number of pixels. Some vision sensors provided by banner Bonner engineering can capture 1.3 million pixels. Therefore, no matter a few meters or centimeters away from the target, the sensor can "see" the delicate target image

after capturing the image, the visual sensor compares it with the reference image stored in memory for analysis. For example, if the visual sensor is set to identify the correct machine part with eight bolts inserted, or the part with misaligned bolts. In addition, the visual sensor can make a judgment no matter where the machine part is located in the field of view and whether the part rotates within 360 degrees

basic elements of visual sensor application

the two key points of mastering how to apply visual sensors are lighting and software tools. For an in-depth understanding of the principle of visual sensors, see and select the vision option

lighting

in the application of visual sensors, lighting is the most important technical factor. The type and location of the light source are directly related to whether the image with the maximum target background contrast can be created

tools

vision sensors use algorithms to analyze their captured images. Vision sensors with a wide range of applications and functions provide a variety of algorithms (sometimes called tools). The low-cost visual sensor may only include one tool, and both of them have their own applications, such as the inspection report produced by the national fire protection building materials quality supervision and inspection center

tools are divided into two basic categories: linear and planar. Both of them pay attention to the changes of images, but in different ways

if the area to be concerned is predictable, the linear tool is the best choice because it is faster and more accurate than the plane tool. For example, the visual sensor can use linear tools (such as cutting tools) to ensure that the pointer returns to zero quickly through the assembly line, and the size bottles have been covered tightly

Figure 2 The broken tablets in the blister package found by the backlit vision sensor

if the position of the target may change, such as a plastic bottle box that may lack one or more plastic bottles at a certain position in the box, the flat tool is the most practical. The flat tool will check whether the whole box deviates from the standard

advantages of visual sensor

among the available inspection alternatives, namely, visual system, photoelectric sensor, manual inspection, and visual sensor. Visual sensor usually becomes the best choice because of its accuracy, ease of use, rich functions and reasonable cost

with the increasingly fierce competition in various industries, the profit margin gradually becomes smaller, and manufacturers cannot afford the high scrap rate caused by defective products. Therefore, in order to detect problems before incurring high costs, manufacturers are integrating inspection into the whole manufacturing process

comparison between vision system and vision sensor

complex vision system is a mature technology that can perform detailed automatic inspection. However, the complexity and high cost hinder its application in many industries, and its price usually ranges from $5000 to more than $50000. These complex vision systems require one or more cameras, customized software, and a computer. They often need to hire external visual consultants to design, integrate and install systems. In addition, given the specificity of such systems, they cannot be easily used for other purposes. These complex systems often require continuous professional support

although the demand for complex vision systems still exists, the introduction of cheaper and easier to use vision sensors provides more cost-effective solutions for some industrial applications. In addition, because visual sensors are smaller and easier to use, manufacturers will use visual solutions more frequently in inspection and verification applications. Visual sensor plays an important role in improving the quality and production efficiency of factory automation

comparison between photoelectric sensor and visual sensor

the New York City Council will conduct an in-depth review on the feasibility of the specific implementation scheme of 1 recycling project on December 19. Compared with photoelectric sensor, visual sensor gives machine designers more flexibility. In the past, applications requiring multiple photoelectric sensors can now use a visual sensor to test multiple features. The vision sensor can check a much larger area and achieve better target position and direction flexibility. This makes vision sensors widely welcomed in some applications that can only be solved by photoelectric sensors. Traditionally, these applications also require expensive accessories and precise motion control that can ensure that the target object always appears in the same position and posture

in addition, since the cost of a basic visual sensor is only equivalent to several photoelectric sensors with expensive accessories, the price is no longer a problem

Figure 3 In the application of drug packaging, visual sensor can identify whether the label is missing on the packaging bottle

vision sensor provides unparalleled flexibility for application switching. For example, the switching of the production process (from a single serving of yogurt to an ice cream bucket) may only take a few seconds and can be completed remotely. Additional inspection conditions can be easily added to this application

comparison between manual inspection and visual sensor

no matter what progress has been made in factory automation, many inspections are still completed with the naked eye. However, in most applications, many of the advantages of visual sensors are beyond the reach of manual inspection processes. The vision sensor can work at a much higher speed; Perform repeated, repeated, and consistent inspections at a much lower cost

Figure 4. After training, know how to monitor the lateral and longitudinal position of the sensor to identify the mislabeled

the expanding application range

the low cost and ease of use of visual sensors have attracted machine designers and process engineers to integrate them into various application fields that once relied on manual work, multiple photoelectric sensors, or did not test at all. Industrial applications of vision sensors include inspection, metrology, measurement, orientation, defect detection and sorting. The following are just some application examples:

in the automobile assembly plant, check whether the glue beads applied by the robot to the door frame are continuous and have the correct width

in the bottling factory, check whether the bottle cap is properly sealed, whether the filling liquid level is correct, and no foreign matters fall into the bottle before sealing

in the packaging production line, ensure that the correct packaging label is pasted in the correct position

in the drug packaging production line, check whether there are damaged or missing tablets in the blister packaging of aspirin tablets

in metal stamping companies, stamping parts are inspected at a speed of more than 150 pieces per minute - more than 13 times faster than manual inspection

conclusion

for visual sensors, this is an exciting moment. Technologies that once required a lot of expertise are now economical and easy to use. Future product development using this technology will continue this trend. The challenge now is how to make various industries aware of the potential of visual sensors in all manufacturing fields, including quality control, measurement and inspection processes