桿式噴藥機行走速度與變率噴量之研究

Abstract

傳統的農耕方式，將農田視為相同性質，給予相同的作業方式或劑量，造成許多農地不當使用、產量顯著降低、肥料與農藥不當施用、資源浪費、毒害氣體釋放或滲漏、有毒物質長期殘留及作物生長環境劣化等問題。為改善以上問題，發展出精準農業技術，能隨著不同的空間與時間，採取不同的作業方法或施用量。本研究設計電路模組，並利用LabVIEW程式軟體作為系統控制中心，偵測以一台模型車模擬自走式桿式噴藥機的行走速度以及控制不同速度下的電路作動，間接改變比例閥的開度，以改變噴藥機的噴霧率。實驗中比例閥開度以前人論文之建議為準則，並進行不同的噴霧壓力與比例閥開度的流量實驗；以LabVIEW的波形圖記錄所讀取的轉速，並改變程式中的參數觀察轉速範圍，並與數位式轉速計量測的實際轉速誤差比較其誤差。實驗結果顯示：幫浦的噴霧壓力越大，噴藥機的流量越高；幫浦的送水量過小會導致噴藥機的流量不符合理論結果，例如比例閥在20%開度的噴霧率與全開開度的噴霧率幾近相同；使用軟體LabVIEW程式中的時序功能計算每一迴圈的脈衝數，再換算成轉速值。實驗中改變間隔時間為0.05秒、0.1秒與0.5秒，發現設定的間隔時間值會影響所讀取轉速值，例如間隔時間為0.05秒時，會讀取到瞬間的極大轉速值，產生極大的轉速偏差，此情形會造成比例閥不正常的作動，例如應該要保持在特定開度時，比例閥卻會被調整到不正確的開度，這樣則將達不到準確控制噴霧量的目的。研究結果顯示：間隔時間為0.5秒時，程式所讀取到的轉速較接近實際轉速，且轉速偏差值較低，不會造成比例閥不正常作動的情形。

The crop production and quality are based on the accurate application rate of chemicals in order to prevent the damage from the pest and disease. The pest will be out of control if the application of pesticide is unsuitable, while it will damage crop, increase cost and cause the environmental pollution. The objective of this research was to develop an automatic sprayer control system. It used a proportional flow control valve to change the flow rate with the speed calibrated by the LabVIEW program. The opening of a proportional flow control valve was to choose to be 20, 34 and 65% with the suggesting values in the previous literature. The flow rate was dependent on the variable operating pressure of a pump and the opening of a proportional flow control valve. The speed showed by the program with the waveform chart in LabVIEW could by analyzed. The variation of the speed with different parameters in program could be found and the speed read from the program could be compared with the actual speed. The results showed that the application rate would be changed proportional with the operating pressure, but the outlet flow rate controlled by a proportional flow control valve was not satisfied as expected because of the smaller capacity of pump. For example, the flow rate of 20% opening of a proportional flow control valve was close to the flow rate of 100% opening. The value of cycle time in the LabVIEW program was used to count the speed, and it would affect the speed measured by this program, and cause the proportional flow control valve running wrong. For example, the speed read from computer program would be an instantaneously extreme value when the value of cycle was 0.05 second, and the opening of the proportional flow control valve may be 40% not 65% as expected. The speed read from computer program was closer to the actual speed when the value of cycle time was 0.5 second, and it won’t produce the extreme value to affect the running of the proportional flow control valve.