基于多层感知机模型的稻麦双变量精准施肥机排肥策略

    Research on fertilizer application strategy for rice-wheat dual-variable precision fertilizer applicator based on MLP

    • 摘要: 变量施肥是实施精准农业的重要技术途径,转速、开度双重调节的外槽轮式变量施肥方式是稻麦轮作区作物施肥的典型方式。针对目前变量施肥机控制系统响应速度慢、预测模型不准确,引起排肥量误差大、成效不显著的问题,本文基于自主研制的稻麦双变量精准施肥机,运用数理统计和机器学习方法,提出一种基于多层感知人工神经网络的排肥量预测模型构建方法,并对其有效性和适用性进行了验证。通过分析莱维飞行算法(levy flight algorithm, LFA)、粒子群算法(particle swarm optimization, PSO)和多层感知器神经网络模型(multilayer perceptron, MLP)的算法机理,结合开度-转速双变量排肥方法,构建LFA-PSO-MLP(LMP)排肥量预测模型;引入开度-转速-排肥量关系模型,利用归一化、正则化等方式改善算法结构,开展参数优化和模型训练,并对比MLP和PSO-MLP模型,得到LFA-PSO-MLP排肥量最优预测模型;构建inverse LFA-PSO-MLP(ILMP)预测模型作为施肥机的神经网络模型,根据目标排肥量快速计算所需开度和转速。试验结果表明:通过对MLP、PSO-MLP和LFA-PSO-MLP三种模型进行对比得出LFA-PSO-MLP模型在拟合50次左右收敛,拟合500次后的R2值为0.999,平均相对误差(MAPE)为1.83%,均优于其他两种模型。LMP验证集验证试验中,预测值和验证值的平均相对误差为2.47%;田间试验中,预测值和实测值的平均相对误差为3.49%;ILMP验证试验中,转速预测的平均相对误差为1.82%;目标排肥量与实际排肥量的最大相对误差为7.22%,平均排肥精度达到93.92%,搭载ILMP模型的施肥机排肥效果较好。研究表明提出的模型构建方法能够在保证排肥量预测精度的同时提升运算效率,实现快速、精准、高效的变量施肥,改善生态效益和经济效益。

       

      Abstract: Variable fertilization is an important technical approach in implementing precision agriculture. The method of external groove wheel-type variable fertilization with dual regulation of speed and aperture is a typical operation method for crop production (planting) in rice-wheat rotation areas. In response to current issues with variable fertilizer applicators such as slow control system response, inaccurate prediction models, large fertilizer amount errors, and insignificant effectiveness, this study, based on a self-developed dual-variable precision fertilizer applicator for rice and wheat, proposed a method for constructing a fertilizer amount prediction model based on a multilayer perceptron artificial neural network using mathematical statistics and machine learning methods, and verified its effectiveness and applicability. By analyzing the algorithm mechanisms of the levy flight algorithm (LFA), particle swarm optimization (PSO), and multilayer perceptron (MLP) neural network models, and combining the dual-variable fertilization method of aperture-speed, a fertilizer amount prediction model based on LFA-PSO-MLP (LMP) was constructed. The model incorporated the aperture-speed-fertilizer amount relationship, improved algorithm structure through normalization, regularization, etc., conducted parameter optimization and model training, and compared the MLP and PSO-MLP models to obtain the optimal LFA-PSO-MLP fertilizer amount prediction model. Furthermore, an inverse LFA-PSO-MLP (ILMP) prediction model was constructed to quickly calculate the required aperture and speed based on the target fertilizer amount. Experimental results showed that the LFA-PSO-MLP model converged in about 50 iterations, with an R² value of 0.999 after 500 iterations and a mean absolute percentage error (MAPE) of 1.83%, which was better than the other two models. Validation tests of the LMP model yielded an average relative error of 2.47% between predicted and validation values, while field experiments showed an average relative error of 3.49% between predicted and measured values. For the ILMP model, the average relative error for rotation speed prediction was 1.82%, and in field experiments, the maximum relative error between target and actual fertilization rates was 7.22%, with an average fertilization accuracy of 93.92%. This indicated that the fertilizer applicator equipped with the ILMP model performed well in fertilizer application. The study demonstrated that the proposed model construction method can ensure the accuracy of fertilizer amount prediction while improving computational efficiency, achieving fast, precise, and efficient variable fertilization, and improving ecological and economic benefits.

       

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