Data-driven multivariate nonlinear mathematical model of landing gear shock absorbers
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摘要:
针对起落架油气混合缓冲器的非线性动态特性,通过数据驱动方法结合理论分析与落震试验,采用伪线性最小二乘法,建立了以过载值为因变量,综合考虑缓冲器行程、速度和加速度等因素的多元非线性数学模型,并通过多次改进显著提高了模型的拟合精度和预测能力。为解决模型预测值与试验数据之间的时延现象,引入加速度项,模型的均方根误差(RMSE)从
0.0447 降低至0.0401 ,调整判定系数从0.968提升至0.974。为进一步改善初始阶段(行程为0~50 mm)的拟合偏差问题,在模型中加入了加速度的0.5次方项,模型的RMSE从0.0401 降低至0.0341 ,调整判定系数从0.974提升至0.981,模型对系统动态行为的描述能力和预测精度显著增强。研究结果表明:所建模型为起落架缓冲器的非线性动态特性提供了更准确的描述方法,并为整机自动控制系统的设计与优化提供了可靠的理论基础。-
关键词:
- 起落架油气混合缓冲器 /
- 数据驱动 /
- 多元非线性模型 /
- 伪线性最小二乘法 /
- 落震试验
Abstract:To address the nonlinear dynamic characteristics of the oleo-pneumatic landing gear strut, this study establishes a multivariate nonlinear mathematical model with overload as the dependent variable, through a data-driven approach combined with theoretical analysis and drop-test data. The model comprehensively incorporates factors such as strut stroke, velocity, and acceleration, and is developed using the pseudo-linear least squares method. Through multiple iterative improvements, the model's fitting accuracy and predictive capability have been significantly enhanced. To resolve the time delay phenomenon observed between model predictions and experimental data, an acceleration term was introduced into the model. This adjustment reduced the root mean square error (RMSE) from
0.0447 to0.0401 and increased the adjusted coefficient of determination from 0.968 to 0.974. A square-root acceleration term (acceleration increased to the power of 0.5) was added to the model in order to further address the fitting deviation problem during the first phase (stroke 0 mm to 50 mm). This refinement reduced the RMSE from0.0401 to0.0341 and increased the adjusted coefficient of determination from 0.974 to 0.981, significantly enhancing the model's ability to describe system dynamics and its predictive accuracy. The study demonstrates that the proposed model provides a more accurate method for describing the nonlinear dynamic characteristics of landing gear shock absorbers and offers a reliable theoretical foundation for the design and optimization of the overall automatic control system. -
表 1 Butterworth滤波器传递函数的分母多项式系数
Table 1. Denominator polynomial coefficients of the Butterworth filter transfer function
n b7 b6 b5 b4 b3 b2 b1 b0 1 1.0000 2 1.4142 1.0000 3 2.0000 2.0000 1.0000 4 2.6131 3.4142 2.6131 1.0000 5 3.2361 5.2361 5.2361 3.2361 1.0000 6 3.8637 7.4641 9.1416 7.4641 3.8637 1.0000 7 4.4940 10.0978 14.5918 14.5918 10.0978 4.4940 1.0000 8 5.1258 13.1371 21.8462 25.6884 21.8462 13.1371 5.1258 1.0000 表 2 对回归系数进行显著性检验的统计量
Table 2. Test statistic for the significance of regression coefficients
系数 估计值 SE $ t $统计量 $ {p}_{\text{value}} $ $ {a}_{0} $ 8.1464 × 10−18.9704 × 10−390.814 0 $ {a}_{1} $ − 9.0978 × 10−31.0834 × 10−4−83.977 0 $ {a}_{2} $ 2.2696 × 10−47.6238 × 10−629.770 4.4202 × 10−172$ {a}_{3} $ 4.3902 × 10−53.3417 × 10−7131.380 0 $ {a}_{4} $ 7.8479 × 10−81.7113 × 10−945.860 0 $ {a}_{5} $ 4.3789 × 10−74.1792 × 10−810.478 2.7918 × 10−25表 3 对模型整体拟合优度检验方面的诊断指标
Table 3. Diagnostic indicators for overall goodness-of-fit test of the model
RMSE $ {R}^{2} $ $ F $统计量 pvalue 0.044 7 0.968 1.92×104 0 表 4 对改善时延的数学模型的回归系数进行显著性检验的统计量
Table 4. Significance test statistics for regression coefficients of time-delay improvement model
系数 估计值 SE $ t $统计量 $ {p}_{\text{value}} $ $ {c}_{0} $ 7.9925 ×10−18.2152 ×10−397.289 0 $ {c}_{1} $ − 9.2222 ×10−39.9970 ×10−5−92.25 0 $ {c}_{2} $ 1.1248 ×10−47.9991 ×10−614.062 1.2714 ×10−43$ {c}_{3} $ 3.4830 ×10−61.2737 ×10−727.346 4.1638 ×10−148$ {c}_{4} $ 4.5151 ×10−53.1374 ×10−7143.91 0 $ {c}_{5} $ 9.1861 ×10−81.6562 ×10−955.465 0 $ {c}_{6} $ 4.9268 ×10−122.5144 ×10−121.9595 5.0147 ×10−2$ {c}_{7} $ 1.1873 ×10−64.6381 ×10−825.99 1.3008 ×10−131表 5 对改善时延的数学模型整体拟合优度检验方面的诊断指标
Table 5. Diagnostic metrics for overall goodness-of-fit testing of time-delay improvement mathematical model
RMSE $ {R}^{2} $ $ F $统计量 pvalue 0.0401 0.974 1.71×104 0 表 6 对改善初始阶段偏差的数学模型的回归系数进行显著性检验的统计量
Table 6. Significance test statistics for regression coefficients of initial-stage deviation improvement model
系数 估计值 SE $ t $统计量 $ {p}_{\text{value}} $ $ {d}_{0} $ 1.194 1.3046 ×10−291.526 0 $ {d}_{1} $ − 1.1916 ×10−21.1175 ×10−4−106.630 0 $ {d}_{2} $ 1.4974 ×10−46.8534 ×10−621.849 9.713×10−99 $ {d}_{3} $ 3.5939 ×10−61.0767 ×10−733.379 8.5131 ×10−210$ {d}_{4} $ 5.1734 ×10−53.1619 ×10−7163.620 0 $ {d}_{5} $ 8.3556 ×10−81.3974 ×10−959.793 0 $ {d}_{6} $ 1.0192 ×10−63.9642 ×10−825.711 1.1927 ×10−132$ {d}_{7} $ − 1.6958 4.8066 ×10−2−35.281 1.6017 ×10−230表 7 对改善初始阶段偏差的数学模型的整体拟合优度检验方面的诊断指标
Table 7. Diagnostic metrics for overall goodness-of-fit testing of mathematical model for improving initial-stage deviation
RMSE $ {R}^{2} $ $ F $统计量 pvalue 0.0341 0.981 2.39×104 0 -
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