Machine vision camera selection

First, clarify the requirements.

First, the accuracy requirements of the tested products must be determined.

Second, you need to determine the size of the field of view that the camera needs to see.

Third, the speed of the object being detected needs to be determined.

Fourth, it is necessary to determine whether it is dynamic or static detection.

Then determine the hardware type.

1. Determining the pixel size of the image plane

Currently, most software on the market offers near-zero precision, often referred to as sub-pixel accuracy. However, while the software is error-free, hardware errors are unavoidable. Therefore, most machine vision systems on the market guarantee an error of one pixel. This leads to the following calculation formula:

Accuracy = Field of view (length or width) ÷ Camera pixels (length or width)

With the above formulas and our first and second requirements, it's not difficult to determine the camera's pixel size.

Assuming a field of view of 10mm and a required accuracy of 0.02mm, then the camera's pixel count would be 10 ÷ 0.02 = 500 pixels. Therefore, a camera with 300,000 pixels (640*480) would be sufficient.

2. Determining the Camera Transmission Method

Currently available camera transmission methods include:

1) Analog camera (PCI acquisition card) can be selected if speed requirements are not high.

Advantages: Stable, cost-effective. Disadvantages: Low frame rate, generally only reaching 25-30 frames per second.

2) USB interface camera systems that only use a single camera can be selected first; high speed is also required.

Advantages: Does not occupy a PCI slot, high frame rate, high cost-performance ratio. Disadvantages: Utilizes system CPU resources.

3) When using multiple cameras in a 1394 interface camera system, selection can be prioritized; when high speed is required, selection can be prioritized.

Advantages: Does not consume system CPU resources, high frame rate; Disadvantages: Occupies a PCI slot, expensive.

3. Selection of camera triggering method

1) Continuous acquisition mode is selectable for static detection, and also for situations where continuous product movement cannot generate a trigger signal.

2) The software triggering mode is selectable for dynamic detection, and the ability to provide trigger signals for continuous product movement is also selectable.

3) Hardware triggering modes are selectable for high-speed dynamic detection; the ability to provide trigger signals during continuous high-speed product movement is also selectable.

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