农业工程学报
農業工程學報
농업공정학보
2013年
18期
26-33
,共8页
优化%模型%农业机械%甜菜%切顶机构%仿形机构%参数
優化%模型%農業機械%甜菜%切頂機構%倣形機構%參數
우화%모형%농업궤계%첨채%절정궤구%방형궤구%삼수
optimization%models%agricultural machinery%sugar beet%beet top cutting mechanism%profiling mechanism
针对现有甜菜切顶机构在切顶过程中切割厚度不能随甜菜青顶大小自动调节问题，提出一种新的切顶机构。对其工作原理进行分析，建立其运动学模型，推导机构各关键点的（角）位移、（角）速度和（角）加速度方程。基于Visual Basic 6.0编写机构的运动学仿真与优化软件，利用该软件分析链轮传动比、齿轮节圆半径、摆臂长度、仿形轮半径等主要参数对切刀切顶轨迹和甜菜青顶切割厚度的影响，并通过人机交互优化方法得到一组较优的机构参数，其对应的切顶轨迹曲线能满足甜菜切顶的农艺要求。基于Matlab语言编程，采用遗传算法对仿形轮线速度和牵引速度进行了分析与优化，优化结果优于经验值。最后，根据优化所得机构参数建立了切顶机构三维模型，通过ADAMS虚拟样机进行试验验证，虚拟试验结果与理论分析结果一致。
針對現有甜菜切頂機構在切頂過程中切割厚度不能隨甜菜青頂大小自動調節問題，提齣一種新的切頂機構。對其工作原理進行分析，建立其運動學模型，推導機構各關鍵點的（角）位移、（角）速度和（角）加速度方程。基于Visual Basic 6.0編寫機構的運動學倣真與優化軟件，利用該軟件分析鏈輪傳動比、齒輪節圓半徑、襬臂長度、倣形輪半徑等主要參數對切刀切頂軌跡和甜菜青頂切割厚度的影響，併通過人機交互優化方法得到一組較優的機構參數，其對應的切頂軌跡麯線能滿足甜菜切頂的農藝要求。基于Matlab語言編程，採用遺傳算法對倣形輪線速度和牽引速度進行瞭分析與優化，優化結果優于經驗值。最後，根據優化所得機構參數建立瞭切頂機構三維模型，通過ADAMS虛擬樣機進行試驗驗證，虛擬試驗結果與理論分析結果一緻。
침대현유첨채절정궤구재절정과정중절할후도불능수첨채청정대소자동조절문제，제출일충신적절정궤구。대기공작원리진행분석，건립기운동학모형，추도궤구각관건점적（각）위이、（각）속도화（각）가속도방정。기우Visual Basic 6.0편사궤구적운동학방진여우화연건，이용해연건분석련륜전동비、치륜절원반경、파비장도、방형륜반경등주요삼수대절도절정궤적화첨채청정절할후도적영향，병통과인궤교호우화방법득도일조교우적궤구삼수，기대응적절정궤적곡선능만족첨채절정적농예요구。기우Matlab어언편정，채용유전산법대방형륜선속도화견인속도진행료분석여우화，우화결과우우경험치。최후，근거우화소득궤구삼수건립료절정궤구삼유모형，통과ADAMS허의양궤진행시험험증，허의시험결과여이론분석결과일치。
As one of the key components of the beet harvester, the beet top cutting mechanism plays a role in the first step of the harvest. The cutting quality has an important impact on the economic benefits of the sugar industries and farmers. In order to solve the problem that the existing beet top cutting mechanism can’t adjust the cutting thickness while the mechanism runs, a new profiling top cutting mechanism was proposed, which consists of a parallel four-bar linkage, chain transmission, gear-rack mechanism, and profiling wheel. When the profiling wheel runs over the big beet top, the cutter attached on the rack will move down by the gear because the profiling wheel is elevated by the beet top. Therefore, the cutting thickness on the big beet top will be large. On the contrary, when the wheel runs over the small beet top, the cutter will move up because the profiling wheel is delegated. Then the cutting thickness will be small. Its working mechanism was analyzed. The kinematic model of this mechanism was established, and the equations of (angular) displacement, (angular) velocity, (angular) acceleration at the key points of this mechanism were derived. Then its kinematic simulation and optimization software was compiled based on Visual Basic 6.0, with which the effects of main parameters such as the sprocket transmission ratio, the gear pitch circle radius, the swing arm length, the profiling wheel radius, etc. on the cutting curve of the cutter and the cutting thickness were analyzed, Under the constraint that the cutting curve and cutting thickness should meet the agronomic requirements, a set of optimal parameters was obtained by the method of human-computer interaction, which was H=570 mm, k=2.4, Rf=180 mm, Rc=100 mm, L1=520 mm. The relationship between the linear velocity of the profiling wheel and the traction speed was analyzed and optimized by the genetic algorithm based on Matlab, and the optimization results were better than the experience values. These optimized parameters of the mechanism were used to build the three-dimensional solid models by the software UG. Then its virtual prototype model was constructed to simulate the kinematics by the software ADAMS. The results were that the cutting curves from the simulation and theoretical analysis were about the same verify that the theoretical analysis of the beet top cutting mechanism is reliable.
