基于三次拉格朗日曲线拟合轨迹的斜置式扎穴机构研究

Oblique Type Pricking Hole Mechanism Based on Lagrange Curve for Cubic Fitting Trajectory

为更好地满足斜置式扎穴机构喷肥针的入出土轨迹姿态以及不损伤作物的农艺要求,提出基于三次拉格朗日曲线拟合扎穴轨迹的逆向设计参数优化方法,为得到理想的"杏胡形"扎穴轨迹,通过改变相对轨迹上若干型值点的坐标,控制喷肥针入出土姿态并建立喷肥针的运动学模型,采用Matlab GUI开发平台,编写了斜置式非规则齿轮行星轮系扎穴机构的逆向设计与运动学分析仿真软件,最终得到非规则齿轮行星轮系的节曲线、喷肥针的入出土角及喷肥针尖的速度随行星架转角的变化曲线。通过高速摄影试验,观察和分析了在扎穴机构不同斜置角度下喷肥针尖相对运动轨迹的变化规律。试验结果表明,随着机构斜置角度的增大,喷肥针轨迹横向尺寸不变,纵向尺寸减小,扎穴轨迹段曲线逐渐向里收缩。在保证喷肥针扎入土壤一定深度情况下,喷肥针入出土角逐渐增大,随着机构斜置角度的增大,喷肥针轨迹的穴口宽度逐渐增大。

The effects of liquid fertilization for concentrating near crop root system are to speed up the absorption of crops and improve the yield and quality of crops. Deep-into type liquid fertilizer applicator makes the liquid fertilizer into the soil. Aiming to meet the agronomic requirement of trajectory and posture of spray fertilizer needle of oblique type pricking hole mechanism when it got into and out soil and spray fertilizer needle did not damage crops,an optimization method of parameters reverse design was put forward based on Lagrange curve for cubic fitting trajectory. In order to obtain the ideal ＂xing hu＂shaped trajectory for pricking hole,the posture of spray fertilizer needle got into and out soil was controlled by changing the coordinates for some types of value points on static trajectory,and then the kinematics model of spray fertilizer needle was established. The simulation software of reverse design and kinematics analysis was compiled,which was written by Matlab GUI development platform. Finally,the pitch curve of non-circular planetary gear trains,the angle of spray fertilizer needle got into and out soil and speed curve of spray fertilizer needle point along with the change of planet frame angle were got. High-speed photography bench was established and tested. The regulars of relative motion trajectory and absolute motion trajectory of spray fertilizer needle in different oblique angles of pricking hole mechanism were observed and analyzed. The results showed that as the oblique angles of institution increased,the lateral size of track of spray fertilizer needle remained the same,the longitudinal size of track of spray fertilizer needle was decreased,the trajectory curve of pricking hole mechanism was gradually inward contraction.The angles of spray fertilizer needle got into and out the soil were increased gradually when the soil depth was certain; as the oblique angles of institution increased,the width of hole mouth was increased.