Explain the composition and working principle of machine vision system in detail

Introduction to the development of machine vision: in the 1960s, machine vision systems began to be studied abroad. Later, with the development of large-scale integrated circuits, vision system began to become practical. In the 1980s, with the rise of microcomputer, machine vision system began to go deep into various fields and its application stepped into fine differentiation. This paper describes the components and working principle of machine vision system in detail.

Composition of machine vision system: it can be seen from the literal meaning of machine vision system that it is mainly divided into three parts: machine, vision and system. The machine is responsible for the movement and control of the machine; Vision is realized by lighting source, industrial lens, industrial camera, image acquisition card, etc; System mainly refers to software, which can also be understood as a complete set of machine vision equipment. Let's focus on the five modules in the machine vision system:

1. Machine vision light source (i.e. lighting light source)

As an important input part of machine vision system, lighting source has a direct impact on the quality of input data and application effect. Since there is no general machine vision lighting equipment, the corresponding visual light source should be selected for each specific application example to achieve the best effect. Common light sources include: LED ring light source, low angle light source, backlight, strip light source, coaxial light source, cold light source, point light source, linear light source and parallel light source.

2. Industrial lens

Lens is mainly responsible for beam modulation and signal transmission in machine vision system. Lens types include: standard, telecentric, wide-angle, close-up and telephoto. The selection basis is generally based on camera interface, shooting object distance, shooting range, CCD size, allowable distortion range, magnification, focal length and aperture.

3. Industrial camera

The most essential function of industrial camera in machine vision system is to convert optical signal into electrical signal. Compared with ordinary camera, it has higher transmission power, anti-interference power and stable imaging ability. According to different standards, there are many classifications: according to the output signal mode, it can be divided into analog industrial camera and digital industrial camera; According to different chip types, it can be divided into CCD industrial camera and CMOS industrial camera, which is the most common classification.

4. Image acquisition card

Although the image acquisition card is only a part of the complete machine vision system, it is also very important, which directly determines the interface of the camera: black and white, color, analog, digital, etc. The typical ones are PCI acquisition card, 1394 acquisition card, VGA acquisition card and GigE gigabit network acquisition card. Some of these acquisition cards have built-in multi-channel switches, which can connect multiple cameras and capture multi-channel information at the same time.

5. Machine vision software

Machine vision software is the key component of automatic processing in machine vision system. According to the specific application requirements, the secondary development of the software package can automatically complete the image acquisition, display, storage and processing. When purchasing machine vision software, we must pay attention to developing hardware environment, operating system and language to ensure stable software operation and facilitate secondary development.

Principle of machine vision system: the purpose of machine vision system is to convert the photographed target into image signal through machine vision products (i.e. light source, lens, camera and acquisition card) and transmit it to machine vision software (i.e. image processing system) to replace human eye measurement, detection and judgment. Its principle is that computer, image processor and related equipment simulate human visual behavior to obtain the information obtained by human visual system. With the development of microcomputer technology, network technology and big data integration technology, it is believed that machine vision system will replace human beings to complete more difficult tasks in the future.