| Multi-channel high speed photoelectric on-line geometric dimension measurement is applied widely and valuable in detection technology. The measure method with CCD(Charge Coupled Device) has advantage over other methods because it is non-contact, accurate, easily handled by computer. At present, several key problems exist in these kinds of measuring gauges, as follows:1. In dynamic measuring process, the same standard rod gets different measuring outcome in different place within measuring range.2. When measuring system is calibrated, different standard rod gets different calibration coefficient.3. If LED array is adopted as light source in the measuring system, the light source unsteadiness due to its temperature characteristic influence the measuring accuracy a bit.4. Through the imaging system, the light source produce uneven light intensity in the whole measuring range in the CCD surface.In the paper, the above key problems are studied and the corresponding answers are presented:1. According to the phenomenon that the same standard rod gets different measuring outcome in different place within measuring range in dynamic measuring process, an arithmetic called double curve-fitting is presented.2. The broken-line linear approximation is given in order to reduce the error caused by the non-linear calibration coefficient.3. According to the temperature characteristic of LED and CCD, a kind of temperature compensation method with voltage adjuster and thermal resistor combined is presented.4. When using low cost long light source, a method of compensating uneven light intensity in the whole measuring range is presented.In the paper, a Photoelectric Width Measuring Device is designed using imaging method, and an Eight-channel Wires Diameter Measuring Sensor System is designed using projection method. The two different gauges meet different requirements of measuring range, measuring accuracy and cost control. In the two gauges, the above... |
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