基于苗钵力学特性的自动移栽机执行机构参数优化试验

Optimization experiment of transplanting actuator parameters based on mechanical property of seedling pot

为有效减少加工番茄机械化移栽过程钵苗基质的损伤,提高移栽机取苗、植苗成功率,该文构建了移栽过程中取苗、植苗阶段加工番茄钵体的力学模型,结合钵体的抗压力学特性试验,研究移栽过程中造成钵苗基质破损、影响取苗、植苗成功率的因素,通过试验分析适合机械化移栽的钵体和移栽机执行机构的相关参数。参数组合重复性验证试验表明:钵体基质配比(珍珠岩:砾石:泥炭)为1∶1∶2,钵体绝对含水率为72%,取苗夹片插入穴孔深度为35 mm,取苗夹片对钵体的夹持角度为14°,投苗点与接苗碰撞点高度为90 mm,鸭嘴锥度为38°时,移栽成功率满足加工番茄穴盘苗机械移栽要求。该研究为机械化移栽的加工番茄钵苗培育农艺及移栽机参数优化设计提供了参考。

To effectively reduce the breakage rate of the tomato pot seedlings medium, and improve the success rate of picking seedlings and transplanting in the process of mechanized transplanting, we analyzed the process of transplanting. Based on the analysis, mechanical models of tomato seedling pot in the stage of taking and transplanting seedling were constructed. In order to reduce the wastage of the pot caused by transplanting enforcement agencies and to take seedlings out successfully, in the experiment, we considered to adjust the clamping angle of picking seedling（7°, 8° and 9°）, pot body absolute moisture content（65%, 70% and 72%）, and the volume proportion of medium material（perlite： gravel： peat as 1：1：2, 1：2：1 and 1：2：6） as the experimental factors. Combined the orthogonal test method of 3 factors and 3 levels, we conducted the seedling pots compressive mechanical property test, and the compressive strength of soil blocks under different schemes. Through using the universal material testing machine, the relationships between compressive force and compressive amount were obtained. The compression elasticity of the soil block was proposed, which was defined as the straight slope between point M（starting point of linear elastic） and point L（yield point）. Compression feature showed that the resistance capacity for compression with deformation increased slowly at first and increased significantly at last. The optimal parameters of the transplanting actuators were obtained, and the seedling pot properties to suit for transplanting were illustrated. By means of repeated verification experiments with optimal factors, the results showed that the transplanting mechanism worked well. The success rate of transplanting could meet the requirements of tomato pot seedling transplanting, the optimal parameter combination was as follows： the volume proportion of medium material was 1：1：2 for perlite, gravel and peat, respectively; the pot moisture content in the medium was 72%; the depth of the picking clip insert soil hole was 35 mm; the clamping angle of picking seedling was 14°. The collision mechanical model of the pot during the period of planting was constructed through the analysis of the process of the collision of the pot and seedlings. The impact of the collision height and angle to the collision was analyzed based on MATLAB software. It was shown that the smaller collision angle and planting height could reduce the collision damage to the pot. The height between the throwing and the planting collision point should be 90 mm and the duckbill taper was 38° by considering the matching of the picking and throwing part of the transplanter, as well as the intensity when the duckbill was embed into the ground and the requirement of the hole size. By repeated verification experiments of optimal factors combination, it was shown that the success rate of picking seedling and planting seedlings was 97.6% and 93.9%, respectively. The seedling back rate was 0.9% and the damage rate was 2.4% when the volume proportion of medium material was 1：1：2 for perlite, gravel and peat, respectively, pot body moisture content was 72%, depth of the picking clip insert soil hole was 35 mm, clamping angle of picking seedling was 14°, height between the throwing and the planting collision point was 90 mm, and the duckbill taper was 38°. As such it can meet the requirement of the tomato transplanting. Therefore, the study provides very important theoretical basis and reference for the cultivating agronomy of tomato pot seedling which is suitable for mechanized transplanting, and also for parameter optimization design of transplanting machine.