基于不确定性预测的气动力建模与主动采样

Aerodynamic modeling and active sampling based on uncertainty prediction

  • 摘要: 神经网络方法作为一种高效高精度建模方法,在多个领域得到广泛应用,但其自身的“黑箱”特性结合工程问题特有的小样本现象使得模型可靠性不足,预测结果不确定性大,严重制约了神经网络模型的使用。为提高神经网络模型的工程适用性,以飞机纵向非定常气动特性为研究对象,利用时间卷积神经网络实现了纵向大幅振荡风洞试验的时域非定常气动力建模,并使用MC-dropout技术对预测结果的不确定性进行评估。在此基础上结合不确定性分析结果,开展了风洞试验样本主动采样。结果表明,模型不确定性可以先验评估预测精度,模型预测误差与不确定性具有强线性关系,主动采样策略较随机采样策略可以最多降低40%的样本需求,验证了该方法在提升黑箱模型可信度与降低建模样本需求量方面的有效性。

     

    Abstract: Neural network methods, as an efficient and accurate modeling approach, have been widely used in various fields. However, the "black box" feature of neural networks, combined with the engineering problem of few-shot phenomenon, leads to insufficient model reliability and high uncertainty in the prediction results, severely limiting the use of neural network models. In order to enhance the engineering applicability of neural network models, this study focuses on the unsteady aerodynamic characteristic and utilizes time convolutional networks (TCN) to model the temporal unsteady aerodynamic forces in large-amplitude oscillatory wind tunnel tests. The MC-dropout technique is employed to evaluate the uncertainty of prediction results. Based on the uncertainty analysis results, active sampling of wind tunnel test samples is conducted. The results indicate that model uncertainty can be used as a prior evaluation of the prediction accuracy. There is a strong linear relationship between the model prediction error and the uncertainty. The active sampling strategy can reduce the required samples by up to 40% compared to the random sampling strategy. This validates the effectiveness of the present method in improving the trustworthiness of black-box models and reducing the number of modeling samples required.

     

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