新世紀梨重量量測裝置之研製

Development of Weighing Device for New-Century Pear

林明宗(Ming-Tsung Lin) ； 林聖泉(Tshen-Chan Lin)

《農林學報》 55卷1期 (2006/03) Pp. 47-63

https://doi.org/10.30089/JAF.200603.0004

摘要

本研究利用光感測元件搭配電路設計製作新世紀梨重量量測裝置，硬體部分包括光遮斷感知器、量測平台、訊號擷取卡、個人電腦；軟體部分則包括LabVIEW程式，以及新世紀梨重量預估法則。光遮斷感知器係由惠斯敦電橋與LM339等電子元件所構成，其中電橋電路由四個電阻器組成，分別為光敏電阻器、470Ω電阻器、與2個精密可謂電阻器，利用變動電阻比例控制光遮斷感知器的工作性能。本研究總共使用60組惠斯敦電橋，分成四群，每次僅一群電橋電路工作，其中光敏電阻器以正6邊形配置的方式安裝在量測平台上。量測平台上方設有光源，照射待測水果使其產生陰影，由被遮住光敏電阻器的數量與位置可推知水果之投影面積與周長。光遮斷感知器送出的訊號，經由訊號擷取卡PCI-6024E進入電腦，配合LabVIEW程式判斷與分析光遮斷感知器的訊號，估算新世紀梨投影面積與周長，並推算其重量。根據結果顯示，估算新世紀梨周長與面積，平均相對誤差均為3.68%，藉此估算重量，其平均相對誤差分別為7.93%與5.17%。本研究主要特色在於運用正6邊形排列之光敏電阻器量測新世紀梨重量，有別於將感測器以矩陣或直線排列方式，因此可以在一定精度要求下，使用較少感測器。

關鍵字

新世紀梨 ； 光電感測元件 ； 選別裝置

並列摘要

The objective of this study is to design a weighing device for New-Century pear. The hardware of the device consists of sensors, measurement platform, DAQ card, and PC. The software of the system is composed of LabVIEW programs as well as the algorithms to estimate weight of pear. We used photosensitive resistors and LM339 to cons1IUct the measurement device. The Wheatstone Bridge, four resistors with one of photosensitive resistor, one 470 Ω resistor, and two precisely adjustable resistors. The Bridge behaves according to the ratios of the resistances. There are sixty sets of the Wheatstone bridges into four groups. Every time only one Wheatstone bridge is allowed to work. The photosensitive resistors were inserted into the cardboard of the measurement platform in right hexagon allocation. The light was ejected from above of the measurement platform when pear was placed on the center. During the measurement experiments, some resistors beneath the pear were blocked from the light, the resistance became larger; some resistors not covered by the pear, the resistance became smaller. The signal then was input to PC via DAQ card. After identifying the locations of the blocked resistors, we can analyze and compute the projected area of the pears. The weight of pear can also be estimated. The results showed that we were able to estimate the projected perimeter and projected area of pear within averaged relative error of 3.86%. To estimate the pear weight, the averaged relative error was below 7.93% based on the projected perimeter; the averaged relative error was below 5.17% based on the projected area. Compared to the devices with sensors in array or line allocations discussed in the literature, we allocated the sensors in right hexagon. We were able to obtain the accuracy with fewer sensors.

並列關鍵字

New-Century pear ； Photosensitive resistor ； Sorting device