With the widespread application of Industry 4.0 in the industrial sector, the digitization and intelligentization of supply, manufacturing, and sales information in production will ultimately lead to rapid, efficient, and personalized product supply. Industry 4.0 systems are applicable to intelligent manufacturing technologies and industrial manufacturing; they are not simply production processes, but rather the communication between products and machines.
Machine vision is a comprehensive technology that includes image processing, mechanical engineering, control, electric lighting, optical imaging, sensors, analog and digital video technology, and computer hardware and software technology (image enhancement and analysis algorithms, image cards, I/O cards, etc.).
A typical machine vision application system includes image capture, a light source system, an image digitization module, a digital image processing module, an intelligent judgment and decision-making module, and a mechanical control and execution module.
Machine vision inspection equipment is a type of machine that has emerged in recent years to replace human eyes in inspecting relevant parts of products. Its widespread application includes the detection of surface defects in products. What are the components of a machine vision inspection equipment system?
Machine vision inspection equipment system accessory components:
1. Industrial Cameras: CMOS cameras, CCD color cameras, area scan cameras, CAMERA-LINK cameras, line scan cameras, infrared cameras, high-speed cameras, 1394 interface cameras;
A smart camera is a highly integrated, miniature machine vision system. It integrates image acquisition, processing, and communication functions into a single camera, providing a multifunctional, modular, highly reliable, and easy-to-implement machine vision system. Furthermore, thanks to the application of the latest DSP/GPU, FPGA, and high-capacity storage technologies, its intelligence level is continuously improving, meeting the diverse application needs of machine vision.
CCD cameras offer excellent image quality and noise reduction. Although the addition of external circuitry increases system size and reduces reproduction costs, it also provides circuit designers with greater flexibility to enhance specific performance aspects of CCD cameras. CCDs are better suited for applications with very high camera performance requirements but less stringent cost control, such as astronomy, high-resolution medical X-ray imaging, and other applications requiring long exposures and stringent image noise control.
The working principle of a CCD camera: The image of the object being measured is focused onto the CCD chip through an optical lens; the timing generation circuit module provides horizontal drive pulses to help the CCD chip complete the conversion, storage, transfer, and reading of photoelectric charge, and convert the optical signal into an electrical signal for output; the signal processing circuit module receives the electrical signal from the CCD chip, and performs preprocessing such as pulse acquisition, holding, automatic gain control, and video signal synthesis, converting the electrical signal output by the CCD chip into the required video format, i.e., video output. In contrast, a machine vision inspection system uses a CCD camera to convert the target object being inspected into an image signal, which is then transmitted to a dedicated image processing system. Based on pixel distribution and information such as brightness and color, this signal is converted into a digital signal. The image processing system performs various calculations on these signals to extract the target's features, such as area, quantity, position, and length, and then outputs results based on preset tolerances and other conditions, including size, angle, number, pass/fail, presence/absence, etc., achieving automatic recognition and judgment functions.
Area scan cameras: These achieve pixel matrix shooting. In a camera's image capture, the detail is determined not by the number of pixels, but by resolution. Resolution is determined by the focal length of the lens used; the same camera will have different resolutions depending on the lens's focal length. Since the number of pixels does not determine image resolution (sharpness), what are the advantages of a high-pixel camera? The answer is simple: fewer shots and faster testing.
Line scan camera: As the name suggests, it is in the form of a "line". Although it is also a two-dimensional image, it is extremely long, several kilobytes in length, while its width is only a few pixels. Generally, this type of camera is only used in two situations: 1. When the field of view to be measured is a long and narrow strip, it is often used for problems such as inspection on rollers.
2. Camera Interface
CameraLink interface: Designed for high-end machine vision applications, offering high speed, high resolution, and excellent noise immunity.
IEEE 1394 (FireWire) interface: A plug-and-play serial interface that can support up to 63 cameras simultaneously, each 4.5 meters apart, with a maximum distance of 72 meters. Supports transmission speeds of 800 Mbits/s and even 3200 Mbits/s.
USB interface: A widely used serial interface. It offers transfer rates up to 480 Mbits/s and can support up to 127 devices simultaneously.
Gigabit Ethernet interface: Based on the Ethernet network connection protocol, it is plug-and-play and enables continuous high-speed data transmission.
3. Lens
Cameras and lenses are usually sold as a set. Lens selection primarily considers the image viewing distance. The lens selection steps are as follows:
1) Calculate the number of pixels corresponding to the shorter side, E=B/C. The number of pixels on both the longer and shorter sides of the camera must be greater than E;
2) Pixel size = Product short side size B / Number of pixels on the short side of the selected camera
3) Magnification = Size of selected camera chip / Field of view of the short side of the camera
4) Resolvable product accuracy = pixel size / magnification (to determine if it is less than C)
5) Objective lens focal length = working distance / (1 + 1 / magnification) Unit: mm
6) The resolution of the image plane must be greater than 1/(2 × 0.1 × magnification). Unit: lp/mm
The selected lens must support a CCD size equal to or larger than the camera's CCD sensor chip. Additionally, the mounting mount must be compatible (C, CS, or F type). Consider the lens's working distance and whether there is sufficient space. If you are still unsure about lens selection, consult the manufacturer's technical support for recommendations based on your application scenario.
4. Image acquisition card
Although the image acquisition card is only one component of a complete machine vision system, it is equally important, directly determining the camera's interface: monochrome, color, analog, digital, etc. Typical examples include PCI acquisition cards, 1394 acquisition cards, VGA acquisition cards, and GigE gigabit network acquisition cards. Some of these acquisition cards have built-in multiplexers, allowing connection to multiple cameras and simultaneous capture of multiple data streams.
5. Machine vision software
Machine vision software is a key component for automated processing in machine vision systems. Depending on specific application requirements, the software package can be further developed to automatically complete image acquisition, display, storage, and processing. When purchasing machine vision software, it is crucial to pay attention to the development hardware environment, operating system, and programming language to ensure software stability and ease of secondary development.
6. Light sources: LED light sources, xenon lighting systems, ultraviolet lighting systems, infrared light sources, fiber optic lighting systems, and fluorescent lighting systems.
As a crucial input component of machine vision systems, the quality of the light source directly impacts the quality of the input data and the application's effectiveness. Since there is no universal machine vision light source, an appropriate light source must be selected for each specific application to achieve the best results. Common light sources include: LED ring lights, low-angle lights, backlights, strip lights, coaxial lights, cold lights, point lights, linear lights, and parallel lights.
