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基于SSA-LSTM-Attention的日光温室环境预测模型

Solar greenhouse environment prediction model based on SSA-LSTM-Attention

  • 摘要: 建立准确的温室环境预测模型有助于精准调控温室环境促进作物的生长发育,针对温室小气候具有时序性、非线性和强耦合等特点,该研究提出了一种基于SSA-LSTM-Attention(sparrow search algorithm-long short-term memory-attention mechanism)的日光温室环境预测模型。首先,通过温室物联网数据采集系统获取温室内外环境数据;其次,使用皮尔逊相关性分析法筛选出强相关性因子;最后,构建环境特征时间序列矩阵输入模型进行温室环境预测。对日光温室的室内温度、室内湿度、光照强度和土壤湿度4种环境因子的预测,SSA-LSTM-Attention模型的平均拟合指数达到了97.9%。相较于反向传播神经网络(back propagation neural network,BP)、门控循环单元(gate recurrent unit,GRU)、长短期记忆神经网络(long short term memory,LSTM)和LSTM-Attention(long short-term memory-attention mechanism)模型,分别提高8.1、4.1、3.5、3个百分点;平均绝对百分比误差为2.6%,分别降低6.5、3.2、2.8、2.5个百分点。试验结果表明,通过利用SSA自动优化LSTM-Attention模型的超参数,提高了模型预测精度,为日光温室环境超前调控提供了有效的数据支持。

     

    Abstract: An accurate and rapid prediction of the greenhouse environment is essential to promote the growth and development of crops. The greenhouse microclimates can be characterized by temporality, nonlinearity, and strong coupling among various environmental factors. In this study, a prediction model was introduced for the solar greenhouse environment, according to the integration of SSA-LSTM-Attention (sparrow search algorithm-long short-term memory-attention mechanism). A novel model was developed to reliably predict the key environmental parameters in greenhouses. Thereby data collection was realized in more informed and effective environmental practice. An IoT (internet of things) data acquisition was utilized to gather extensive environmental data from both inside and outside the greenhouse. Firstly, Pearson correlation analysis was applied to the vast amount of data. The most significantly correlated factors were identified with the greatest impact on the greenhouse environment. Thereby the efficiency of the model was improved using variables. Then, a time series dataset of environmental features was constructed to encapsulate the temporal dynamics and interdependencies within the data. This dataset served as the input for the SSA-LSTM-Attention model. The complex patterns and relationships were captured using the dataset. Three components were selected: the sparrow search algorithm (SSA) for the hyperparameter optimization, the Long short-term memory (LSTM) network for the temporal dependencies, and the attention mechanism for the most relevant information within the input sequence. Four environmental factors were predicted in the solar greenhouses: indoor temperature, indoor humidity, light intensity, and soil moisture content. The SSA-LSTM-Attention model was achieved in an exceptional average fitting index of 97.9%. This outstanding performance was achieved the best, compared with the benchmark models, including BP (back propagation neural network), GRU (gate recurrent unit), LSTM, and LSTM-Attention (long short-term memory-attention mechanism). Specifically, the SSA-LSTM-Attention model also outperformed the BP, GRU, LSTM, and LSTM-Attention by 8.1, 4.1, 3.5 and 3 percentage points, respectively, in terms of prediction accuracy. Furthermore, a remarkably low average absolute percentage error of 2.6%, which was significantly lower than the errors recorded by the four control models, with reductions of 6.5, 3.2, 2.8 and 2.5 percentage points, respectively. The experimental results demonstrated that the sparrow search algorithm was optimized to improve the LSTM prediction accuracy by the attention mechanism. In conclusion, the sparrow search algorithm was integrated with the automatic hyperparameter optimization of the LSTM-Attention model. Advanced machine learning can be expected to serve as a complex agricultural challenge. The findings can provide invaluable data support for the environmental regulation in solar greenhouses. The model can hold the promise to more precisely control and optimize the critical environmental influencing factors on crop growth. The resource use efficiency significantly enhanced the crop yields. Ultimately, a great contribution can be gained in the sustainable greenhouse.

     

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