Along with the development of four-wheel positioning technology, a variety of high-tech four-wheel rode out, many manufacturers to catch up with the trend of the market, will be many low-end products as high-tech products, in order to trick customers. Common way of four-wheel testing on the market at present basically has: laser, PSD, CCD and 3 d. To ensure the customer can buy a real performance excellence four-wheel, will now laser, PSD, CCD, and are there advantages to using 3 d product, analysis is as follows:

Laser:

Laser is a new type of light source, it is as the light source is applied to four-wheel measurement system, due to the laser output is based on a vertical straight line, thus determines the range of the laser beam of products is relatively narrow, without compensation and artificial calculation thrust line, the measuring accuracy is low, slow speed detection. Because of the light spot and the relationship between the scale, there is human error, and laser is vulnerable to interference, so do with laser light source is applied to four-wheel is not ideal.

It is well known that laser has certain harm to the human eye vision, so it's difficult to UL, CE and other safety certification through, Europe and the United States, Japan has already been eliminated, only in China and some southeast Asian countries but also local presence.

Second, the PSD:

The PSD is also called photoelectric position sensor. As we know, almost all the foreign four-wheel positioning is not used, only in the extensive use of South Korea's machine, its working principle is: when the PSD receives a position the presence of light, its output current will have corresponding change, thus can get light position, it is a species than (DC/AC conversion, there will be data loss) device. By using special technology can avoid these problems to some extent, but in principle limit it can only measure single spot is can't change. PSD can be used in industrial environment, that is, the PSD of temperature drift and seriously affected by ambient light. Temperature changes can make the output zero a few millivolts, the influence of light make the system value is not stable, superposition of the two together, then lose the PSD measurement precision and stability of the equipment, this is the PSD killer (not accurate measurement, repeatability is poor).

Three, CCD:

CCD is a kind of digital semiconductor components (also called photoelectric coupling device), it is divided into linear CCD and CCD two kinds. It is developed in the early 1970 s new semiconductor integrated optoelectronic devices, it is on a silicon surface integration with thousands of separate photosensitive element, when the light to the photosensitive surface, yuan will gather photoelectron of the light, through the way of displacement, the light output, produce light position information of light intensity, so the CCD has high measurement precision (within 0.05 degrees), temperature coefficient, long life and other characteristics.

Using CCD has a good environmental adaptability. All other technology have restrictions on the use of all kinds, such as cannot be used in the light the place with complex, cannot have strong electromagnetic field, the temperature can't have too big change, and so on, and these are all the typical environment of garage. Those who can't open the door, can't open the window, the cool morning measurement data and noon heat measurement is different, cannot have big motor at the request of the nearby, for four-wheel positioning, it is a bit too much. So the European and American countries in the production of four-wheel adopts CCD technology.

Four, 3 d:

3 d measurement method is to use 3 d image recognition technology. With a digital camera mounted on a wheel reflector collecting the three-dimensional image information, have been calculated through computer detection car four-wheel location data, is a fairly advanced measurement method. "V3D" core part only, four target board and computer camera, except there is no any electronic components, with its simple to use, quick measurement, precise and is not affected by the excellent properties of light interference, little fault such as revolutionary and end up in four-wheel positioning market monopoly.