| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 104 === Magnetic rotary encoders are widely used for angular positioning and velocity feedback in high precision servo systems. Hence, the sensing accuracy, repeatability and resolution of the rotary encoder are of great importance. The aim of this research is to analyze several kinds of mechanical errors that influence the accuracy and repeatability of the magnetic rotary encoder. These are roundness and concentricity of the encoder and alignment error of sensor. In addition, a higher detecting gap of the sensor may also cause inferior repeatability of encoder signal. This paper provided a mathematical model to explain how the eccentricity, also known as an alignment error, affected accuracy. We proposed a method for calculating the eccentricity via measuring the radial run-out of the encoder. An experimental study was performed to verify the correctness of the proposed mathematical model. With eccentricity calibrated, the accuracy of the rotary encoders are greatly enhanced. Also, we summed up experimental results and established the relationship between errors and the performance of magnetic rotary encoder. After doing the system error analysis of the magnetic rotary encoder, this research also set up an auto-calibration system for eccentric error based on the concept of automated optical inspection. By integrating an industrial camera and optical lens, image processing program by IMAQ vision and automatic calibrating tool, we were capable of aligning to the magnetic rotary encoder precisely.
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