電腦輔助鳳梨苗種植機構之動力分析

Abstract

鳳梨是台灣重要的經濟果樹之一，是台灣水果出口之冠，然而台灣卻一直沒有一台專用的種植機來促進其生產。團隊因而開發了自走式鳳梨苗鋪布及種植一貫作業機，幫助農民種植鳳梨過程中的鋪布和種植工作。 鳳梨苗種植機通過一個鴨嘴機構進行種植，使用一個多桿機構控制鴨嘴的運動以及開合。因為鳳梨田裡可能會存在些許小石頭或者遺留下的殘根，而鴨嘴部與種植部其他機構強度相差較大，因此當鴨嘴部與石頭發生碰撞時，最可能在鴨嘴部分發生損壞。本研究目的在於模擬分析鴨嘴碰撞時的受力和變形等機械表現。 本研究先使用電腦輔助軟體SolidWorks對機構進行建模，而後使用SolidWorks Motion對種植部機構運動規律進行分析，分析機構的運動速度及動量大小。而後通過運動速度確定碰撞發生時的具體速度，通過動量大小確定碰撞發生時機構慣性，進而確定添加之等效質量塊的質量。因碰撞發生時所處的環境具有不確定性，因此我們將其分為兩種情況進行分析，分別是機構因碰撞而停止和機構不受碰撞影響壓縮鴨嘴兩種情況。最後在Ansys Workbench中進行模擬分析。 模擬結果顯示，當碰撞使機構停止時，碰撞過程是彈性碰撞，鴨嘴機構不會發生塑性變形，碰撞時間為0.0488 s，在碰撞減速過程中，石頭對鴨嘴的平均作用力為192 N。當機構不受碰撞影響壓縮鴨嘴時，鴨嘴很快就產生了塑性變形，造成機構的損壞，塑性變形發生在鴨嘴下方。若要在同等條件下更換材料使鴨嘴完全不變形，則選用的材料降伏強度要達907 MPa，於經濟因素考慮不佳。選用高於原材料的降伏強度之材料可以增強種植過程中的機構安全種植裕度，深處的石頭較不容易損壞機構，然而當增加的降伏強度較少時，對機構安全種植裕度的提升不大，當降伏強度大於550 MPa以後，對安全種植裕度影響較大。基於效率與經濟性考慮，進行更加精細的整地工作是防止機構受損的最佳方法。

Pineapple is an important economic fruit trees of Taiwan, and it is the fruit export champion of Taiwan. However, Taiwan has never had a dedicated planter to promote its production. Therefore, the team developed a self-propelled operation machine to help farmers in the process of laying plastic sheet and planting pineapples seedling. The pineapple seedling planter is planted through a duck-billed mechanism, which uses a multi-rod mechanism to control the movement and opening of the duckbill. Because there may be some small stones or residual roots in the pineapple field, and the strength of the duck-billed mechanism and the other parts of the planting department are quite different, when the duck-billed mechanism collides with the stone, it is most likely that the duck-billed mechanism is damaged. The purpose of this study is to simulate and analyze the mechanical behaviors such as force and deformation during duckbill collision. In this study, the computer-aided software SolidWorks was used to model the mechanism, and then SolidWorks Motion was used to analyze the movement laws of the planting mechanism, and analyze the movement speed and momentum of the mechanism. Then the specific speed at the time of the collision is determined by the speed of the movement, and the inertia of the mechanism at the time of the collision is determined by the momentum, and then the mass of the equivalent mass added is determined. Due to the uncertainty of the environment in which the collision occurred, we divided it into two situations for analysis, namely, the mechanism stopped due to the collision and the mechanism was not affected by the collision and compressed the duck-billed mechanism. Finally, simulation analysis was performed in Ansys Workbench. Simulation results show that when the collision stops the mechanism, the collision process is an elastic collision, and the duck-billed mechanism does not undergo plastic deformation. The collision time is 0.0488 s. During the collision deceleration process, the average force of the stone on the duckbill is 192 N. When the mechanism compresses the duck-billed mechanism without being affected by the collision, the duck-billed mechanism quickly undergoes plastic deformation, causing damage to the mechanism, and the plastic deformation occurs below the duck-billed mechanism. In order to change the material under the same conditions so that the duck's beak does not deform at all, the yield strength of the selected material must reach 907 MPa, which is not considered well for economic reasons. Selecting a material with a yield strength higher than the raw material can enhance the safe planting margin during the planting process. The deep stones are less likely to damage the mechanism. However, when the increased yield strength is less, the safety planting margin is not greatly improved. When the yield strength is greater than 550 MPa, it has a greater impact on the margin of safe planting. Based on efficiency and economic considerations, more detailed land preparation is the best way to prevent damage to the organization.