Design and experiment of precision fertilization device with automatic target for banana stalk
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摘要:目的
针对华南地区蕉园施肥模式不能满足农艺要求、施肥效率低以及施肥机械自动化程度低等问题,设计一种香蕉假茎自动对靶精准施肥装置。
方法根据蕉园实际沟施过程和农艺要求,确定装置的控制原理和关键部件的安装位置,并基于此建立施肥时间滞后模型;对外槽轮排肥器结构进行创新设计,建立排肥机构单圈排肥量和周期排肥量的数学模型,并通过EDEM仿真对肥料运动特性进行验证。采用响应曲面优化方法对排肥机构的工作参数进行优化,满足香蕉在不同生长时期的需肥要求,并以施肥量变异系数、施肥长度变异系数和假茎中心偏移距离为评价指标,进行最优参数组合下的田间试验,进一步验证精准施肥装置的工作性能。
结果确定排肥机构最优工作参数为:排肥轴转速85 r/min,槽轮内芯初始有效工作长度6 mm。田间试验结果表明,施肥量变异系数和施肥长度变异系数均小于4%,假茎中心偏移距离平均值最高为7.4 cm,满足农艺要求。
结论该施肥装置工作性能可满足香蕉施肥要求,本研究可为蕉园精准施肥装置的设计提供参考。
Abstract:ObjectiveIn order to solve the problems that the fertilization mode of banana orchard in South China does not meet the agronomic requirements, the fertilization efficiency and the automation level of fertilization machinery are low, a precision fertilization device with automatic target for banana stalk was designed.
MethodAccording to the fertilization process and agronomic requirement of banana orchard, the control principle of the device and the installation location of key components were determined, and the time lag model related to fertilization was established. Through the innovative design of the fluted fertilizer distributer, the mathematical models of single cycle and periodic fertilization amount were established, and the motion characteristics of fertilizer were verified by EDEM simulation. In order to meet the fertilizer requirements of banana at different growth stages, the response surface methodology was used to optimize the parameters of fertilizer discharging mechanism. The variation coefficient of fertilization amount, variation coefficient of fertilization length and offset distance from the center of banana stalk were used as the evaluation indexes. Field test was performed using the combination of optimization parameters to further verify the performance of the precision fertilization device.
ResultThe optimal parameters were determined as follows: The rotational speed of fertilizer-distributer shaft was 85 r/min, and the initial length of inner core of fluted roller was 6 mm. The field test showed that the variation coefficients of fertilization amount and fertilization length were both below 4%, and the highest average offset distance from the center of banana stalk was 7.4 cm, meeting the agronomic requirements.
ConclusionThe working performance of the device can meet the requirements of banana fertilization. This study can provide references for the design of the precision fertilization device for banana orchard.
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Keywords:
- banana /
- target /
- fertilization device /
- fertilizer discharging mechanism /
- EDEM simulation
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图 3 排肥机构结构示意图
1:排肥轴;2:链轮;3:槽轮内芯;4:阻肥刷;5:外芯支撑板;6:槽轮外芯;7:外芯连接法兰;8:电缸推杆连接法兰;9:步进电缸;10:半圆型垫片;11:排肥管;12:排肥器外壳;13:内芯档环
Figure 3. Structural diagram of fertilizer discharging mechanism
1: The shaft of fertilizer distributer; 2: Sprocket; 3: Inner core of fluted roller; 4: Fertilizer blocking brush; 5: Outer core supporting plate; 6: Outer core of fluted roller; 7: Flange of outer core; 8: Flange of electric cylinder; 9: Electric cylinder; 10: Simicircle gasket; 11: Fertilizer discharging tube; 12: The casing of fertilizer distributer; 13: Inner core retainer
图 4 槽轮断面剖视图
R为外槽轮半径,cm;r为辅助圆O1的半径,cm;$ \alpha $为2个排肥齿脊间的圆心角弧度;$ \varphi $为辅助圆O1中与$ \alpha $相对应的圆心角弧度;$ {f}_{1} $表示槽轮凹槽截面顶部面积,cm2;$ {f}_{2} $表示槽轮凹槽截面底部面积,cm2
Figure 4. Section view of fluted roller
R is the radius of fluted roller, cm; r is the radius of the auxiliary circle O1, cm; $ \alpha $ is the center angle radian between the two tooth ridges of fluted roller; $ \varphi $ is the center angle radian of the auxiliary circle O1 corresponding to $ \alpha $; $ {f}_{1} $ is the top area of the groove section of fluted roller, cm2; $ {f}_{2} $ is the bottom area of the groove section of fluted roller, cm2
图 7 对靶探测示意图
$ D $为香蕉假茎直径,cm;$ {L}_{\mathrm{h}} $ 为超声波传感器离假茎中心的探测距离,cm;$ {L}_{{\rm{b}}} $为超声波传感器和排肥器出肥口在水平方向上的距离,cm;$ {L}_{1} $为超声波传感器探测时间段内试验平台的前进距离,cm;$ {L}_{2} $为信号消失时超声波传感器和假茎中心在水平方向上的距离,cm;$ \alpha $为超声波传感器的波束角,(°);$ v $为试验平台前进速度,cm/s
Figure 7. Schematic diagram of target detection
$ D $ is the diameter of banana stalk, cm; $ {L}_{\mathrm{h}} $ is the distance from ultrasonic sensor to the center of the banana stalk, cm; $ {L}_{{\rm{b}}} $ is the horizontal distance between the ultrasonic sensor and the outlet of the fertilizer distributer, cm; $ {L}_{1} $ is the moving distance of the test platform during the ultrasonic sensor detection period, cm; $ {L}_{2} $ is the horizontal distance between the ultrasonic sensor and the stalk center when the signal disappears, cm; $ \alpha $ is the beam angle of the ultrasonic sensor, (°); $ v $ is the working speed of the test platform, cm/s
图 9 槽轮内芯初始有效工作长度与最大有效工作长度对施肥量的交互作用
a1、a2和a3分别为排肥周期2、3、4 s时的响应面3D图;b1、b2和b3分别为排肥周期2、3、4 s时施肥量(g)的等高线图
Figure 9. Interactive effect of initial length and maximum length of inner core on fertilization amount
a1, a2 and a3: 3D maps of response surfaces under the fertilization cycle of 2,3,4 s, respectively; b1, b2 and b3: Contour maps of fertilization amount (g) under the fertilization cycle of 2,3,4 s, respectively
表 1 全局变量参数设置
Table 1 Setting of global variable parameters
项目
Item直径/mm
Diameter泊松比
Poisson
ratio剪切模量/Pa
Shear
modulus密度/
(kg·m−3)
Density恢复系数
Recovery
coefficient静摩擦系数
Static friction
coefficient动摩擦系数
Kinetic friction
coefficient肥料颗粒
Fertilizer3.37 0.25 1.0×107 1330 排肥器
Fertilizer distributer0.43 1.3×109 1240 肥料颗粒−肥料颗粒
Fertilizer-fertilizer0.11 0.30 0.10 肥料颗粒−排肥器
Fertilizer-fertilizer distributer0.41 0.32 0.18 肥料颗粒−模拟地面
Fertilizer-ground model0.30 1.26 1.27 表 2 试验因素和水平表
Table 2 List of test factors and levels
水平
Level因素 Factor 槽轮内芯初始有效
工作长度/mm
Initial effective working
length of inner core
(A)槽轮内芯最大有效
工作长度/mm
Maximum effective working
length of inner core
(B)槽轮外芯移动
周期/s
Movement cycle
of outer core
(C)排肥轴转速
/(r·min−1)
Rotational speed of
fertilizer-distributer shaft
(D)−1 5 30 2 50 0 10 40 3 75 1 15 50 4 100 表 3 试验方案和结果
Table 3 Test plan and results
试验序号
Test No.A B C D 排肥量/g
Fertilization amount1 0 −1 0 1 167.04 2 −1 0 −1 0 98.98 3 1 0 −1 0 123.65 4 0 1 1 0 270.04 5 −1 1 0 0 185.34 6 0 0 −1 1 140.93 7 0 1 0 −1 144.92 8 0 0 1 −1 159.70 9 0 0 0 0 107.13 10 0 1 −1 0 136.28 11 1 0 1 0 245.21 12 −1 −1 0 0 112.70 13 1 1 0 0 221.92 14 1 0 0 1 234.64 15 0 0 1 1 280.96 16 1 0 0 −1 132.81 17 0 0 −1 −1 80.37 18 0 −1 0 −1 93.45 19 1 −1 0 0 151.00 20 −1 0 0 1 187.33 21 0 −1 1 0 175.50 22 0 −1 −1 0 87.55 23 −1 0 0 −1 106.87 24 −1 0 1 0 198.03 25 0 1 0 1 257.22 表 4 排肥量方差分析表
Table 4 Variance analysis of fertilizer discharge
方差来源
Variation source平方和
Sum of squares自由度
Degree of freedom均方
Mean squareF P 模型 Model 86473.33 14 6176.67 10161.27 < 0.0001 A 4032.60 1 4032.60 6634.06 < 0.0001 B 15299.59 1 15299.59 25169.46 < 0.0001 C 36485.04 1 36485.04 60021.77 < 0.0001 D 25208.33 1 25208.33 41470.40 < 0.0001 AB 0.74 1 0.74 1.22 0.2958 AC 126.68 1 126.68 208.39 < 0.0001 AD 114.17 1 114.17 187.82 < 0.0001 BC 524.64 1 524.64 863.09 < 0.0001 BD 374.62 1 374.62 616.28 < 0.0001 CD 921.12 1 921.12 1515.34 < 0.0001 A2 2523.14 1 2523.14 4150.83 < 0.0001 B2 2618.56 1 2618.56 4307.81 < 0.0001 C2 2496.20 1 2496.20 4106.52 < 0.0001 D2 2271.47 1 2271.47 3736.81 < 0.0001 残差
Residual6.08 10 0.61 总误差
Total error9.41 24 表 5 最佳参数优化结果
Table 5 Results of parameter optimization
序号
No.A B C D 排肥量/g
Fertilization amount1 5.7 38.6 2 82.5 100 2 5.0 48.7 3 86.0 200 3 6.6 50.0 4 85.4 300 表 6 田间试验数据与结果1)
Table 6 Data and results of field experiment
试验编号
No. of test组别1 Group 1 组别2 Group 2 组别3 Group 3 施肥
量/g
Fertilization
amount施肥长
度/cm
Fertilization
length假茎中心
偏移距离/cm
Offset distance
from the center
of banana stalk施肥
量/g
Fertilization
amount施肥长
度/cm
Fertilization
length假茎中心
偏移距离/cm
Offset distance
from the center
of banana stalk施肥
量/g
Fertilization
amount施肥长
度/cm
Fertilization
length假茎中心
偏移距离/cm
Offset distance
from the center
of banana stalk1 104.9 62.3 6.8 207.9 96.3 7.8 310.6 129.3 6.9 2 103.2 64.6 7.9 203.2 97.6 6.8 308.6 125.7 6.5 3 106.1 61.5 7.6 210.6 94.7 6.7 308.2 131.9 7.6 4 107.6 65.7 7.1 209.4 97.5 7.5 302.9 126.2 7.9 5 103.9 67.8 7.6 208.8 100.3 7.5 312.8 123.4 7.0 均值
Average105.1 64.3 7.4 207.9 97.2 7.2 308.6 127.3 7.1 变异系数/%
Coefficient of
variation1.49 3.54 5.33 1.22 1.88 5.94 1.06 2.33 7.01 1) 组别1~3的理论施肥量分别为100、200和300 g,理论施肥长度分别为60、90和120 cm
1)The theoretical fertilization amount of group 1 − 3 were 100, 200 and 300 g, and the theoretical fertilization lengths were 60, 90 and 120 cm, respectively表 7 施肥量对比及误差分析
Table 7 Comparison and error analysis of fertilization amount
组别
Group施肥量/g Fertilization amount 误差/% Error 理论
Theory仿真
Simulation实际
Field
experiment理论与实际施肥量
Fertilization amount between
theory and field experiment理论与仿真施肥量
Fertilization amount between
theory and simulation1 100 98.6 105.1 5.1 1.4 2 200 193.7 207.9 3.9 3.1 3 300 292.4 308.6 2.8 2.5 -
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