割刀位置比例控制液壓系統之研究

Abstract

本研究主要目的為研製出一套可自動調節高度的割刀位置控制系統，期望控制採收機的割刀位置，使其在工作時能隨著作物採摘高度變化或地面高度變化而改變。首先，使用液氣壓電腦輔助設計分析軟體(Automation Studio)模擬整個比例油壓系統之操作特性，最後實際安裝比例液壓系統測試其可行性。 位置控制系統使用具有比例閥的液壓裝置，感測系統為超音波感測機構，使用超音波感測機構擷取作物適當採摘位置，超音波感測訊號經由單晶片(8051)處理，通過RS-232傳送至電腦程式控制端。人機控制介面是以Visual Basic 6.0軟體為基礎。經由USB-4711介面卡傳至比例閥放大器輸入端驅動比例閥，調整割刀位置。 本研究整合電腦、比例閥液壓裝置、A/D、D/A介面及超音波感測器，建立一回授控制系統，超音波感測機構在實驗中能有良好的穩定性和準確性，割刀位置控制系統在輸入步階與方波訊號之實驗中都有不錯的穩定性。應用超音波感測機構從田間實際擷取金露花位置變化進行測試，其結果顯示本系統對於高度變化有著理想的追隨性。

The purpose of this study is to develop an automatic control system for the cutter-height adjustment of tea pluckers. Using Automation Studio design software, the proportional control hydraulic system was simulated on the computer. The characteristics needed by the system were discovered and the feasibility of the system was tested by the simulation. A hydraulic device with a proportional valve was used for the position control. An ultrasonic sensor was also mounted on the system to detect the distance between the cutter on the plucker and the testing surface, like tea tree. A human-machine interface was built using software called Visual Basic 6.0. This interface used a RS-232 port and could receive data from an ultrasonic sensor (SRF05), Then the commands, were be sent to a proportional amplifier through a Multifunction Module called USB-4711. To establish a feedback control system, a personal computer, a proportional control hydraulic system, an A/D and D/A converter and an ultrasonic sensor were combined in this study. The system had accurate dynamic responses to the steady states by the tests with unit-step and square-wave signals. After the experiments with the ultrasonic sensor in the field, this system showed a good height tracing ability.