Optimal control of fruit-storage process using an intelligent control technique

本文以提高水果贮藏质量为目标，研究了基于模糊逻辑、神经网络和遗传算法的水果贮藏过程辨识与优化控制新技术。1)利用传感器研究了贮藏过程中不同环境因素（温度和相对湿度）对果实水分流失和果皮颜色的影响。它们显示了与环境变化的阶跃输入相反的动态变化。水分流失与环境的关系具有线性特征，而肤色与环境的关系具有强非线性特征。因此，应将其视为动态非线性系统。2)三层神经网络对水分损失等线性系统和皮肤颜色（成熟度）等非线性系统均有较好的辨识效果。另一方面，通过对所识别的神经网络模型的仿真，证明了遗传算法在寻找温度和相对湿度的最优设定值方面是非常有效的。3)提出了一种新的模糊控制技术，利用神经网络和遗传算法有效地选择最优隶属函数和控制规则，并将其应用于果库相对湿度的控制。控制输入是通断通风。控制目的是通过模糊控制通风的开关控制，使仓库内的相对湿度保持在理想值。结果表明，该控制方法能较好地确定最优隶属函数和控制规则，控制性能优于常规控制。4)最后，采用神经网络和遗传算法相结合的智能控制技术，根据番茄的表面颜色，研究了番茄贮藏期间的最佳热处理方式。得到了两种最优热处理方法。一种是单次加热，类似于传统的加热方式，另一种是间歇加热，定期加热。最后，将两种最优处理方法应用于实际系统。结果表明，与连续冷却相比，它们的成熟效果更好。少

In this study, new techniques for indentification and optimal controle of fruit-storage process using fuzzy logic, neural networks and genetic algorithms were developed, aiming at the qualitative improvement of fruit during storage.1) Fruit responses (water loss and skin color), as affected by environmental factors (temperature and relative humidity), during stroage were investigated using sensors. They showed dynamic changes against the step inputs of the environmental changes. The relationship between the water loss and the environment is characterized by linear while the relationship between the skin color and the environment is give by strong nonlinearity. So, it is found that they should be treated as dynamic and nonlinear systems.2) A three-layr neural network was effective for both indentification of the linear system such as a water loss and the nonlinear system such as a skin color (ripening). On the other hand, genetic algorithms were shown to be very effective to find the io … More ta-steps of optimal setpoints on temperature and relative humidity through simulation of the identified neural-network model.3) A new fuzzy control technique, which efficiently selects optimal membership functions and control rules by using neural networks and genetic algorithms, was developed and then applied to the control of relative humidity in a fruit-storage house. The control input is the on-off of ventilation. The control aim is to maintain the relative humidity in the storage house at the desired value through the on-off control of ventilation by the fuzzy control. Results show that this control technique allowed optimal membership functions and control rules to be successfully determined and its control performance was superior to the conventional control.4) Finally, an optimal pattern of heat treatment for tomatoes during storage was investigated based on their surface color, using an intelligent control technique consisting of neural networks and genetic algorithms. Two types of optimal heat treatments were obtained. One was the single application of heat, which is similar to the conventional type, and the other was intermittent application, given periodically. Finally, the two optimal treatments were applied to an actual system. The result showed that they gave better results on ripening than continuous cooling. Less