Performance Improvement of Weighing System for a Weighing Sorter

• Main Authors: Chun-Chien Chang, 張竣傑
• Other Authors: 李允中
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/19970091217535314811

碩士 === 國立臺灣大學 === 生物產業機電工程學研究所 === 95 === Weighting sorter is one of the most popular machinery found in produce packers. Although load cell has been commercially applied in weight measurement for a long time, but in Taiwan it is still limited to be used in produce weighting sorter. Noise occurred by movement of mechanical elements and vibration of frame of the sorter greatly interference the weight measurement accuracy. In the thesis, by the use fast Fourier transform for the dynamic measurement signals of the load cell in a commercial sorter were identified as weighting signals distributed from 1 to 15Hz and the vibration noise mainly around 30Hz. Two methods were then implied to reduce the vibration noise in order to decrease the dynamic measurement error. First, a commercial software Multisim was used to simulate and design Twin-T band reject filters with cut-off frequency at 30Hz, filters were then realized through RC and Op-Amps circuits and were examined in dynamic measurements. The high quality Twin-T band reject filter with Q=0.65 gave the best results, the dynamic measurement error were lowered to ±5％. The second approach was to design a deconvolution filter using Simulink schema. Based on the dynamic response of the measurement system a deconvolution filter was simulated and materialize in the Simulink environment. The dynamic measurement signals were first digitally smoothed to eliminate high frequency noise and then processed with the deconvolution filter. With these process the dynamic measurement error were lowered to ±2 ％, that is fairly acceptable in the commercial measurement for a produce weighting sorter.