不確定性環(huán)境下維納模型的隨機變分貝葉斯學(xué)習
doi: 10.16383/j.aas.c210925
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重慶大學(xué)自動(dòng)化學(xué)院 重慶 400044
Stochastic Variational Bayesian Learning of Wiener Model in the Presence of Uncertainty
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School of Automation, Chongqing University, Chongqing 400044
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摘要: 多重不確定性環(huán)境下的非線(xiàn)性系統辨識是一個(gè)開(kāi)放問(wèn)題. 貝葉斯學(xué)習在描述、處理不確定性方面具有顯著(zhù)優(yōu)勢, 已在線(xiàn)性系統辨識方面得到廣泛應用, 但在非線(xiàn)性系統辨識的應用較少, 且面臨概率估計復雜、計算量大等難題. 針對上述問(wèn)題, 以典型維納(Wiener)非線(xiàn)性過(guò)程為對象, 提出基于隨機變分貝葉斯的非線(xiàn)性系統辨識方法. 首先對過(guò)程噪聲、測量噪聲以及參數不確定性進(jìn)行概率描述; 然后利用隨機變分貝葉斯方法對模型參數進(jìn)行后驗估計. 在估計過(guò)程中, 利用隨機優(yōu)化思想, 僅利用部分中間變量概率信息估計模型參數分布的自然梯度期望, 與利用所有中間變量概率信息估計模型參數比較, 顯著(zhù)降低了計算復雜性. 該方法是首次在系統辨識領(lǐng)域中的應用. 最后, 利用一個(gè)仿真實(shí)例和一個(gè)維納模型的Benchmark問(wèn)題, 證明了該方法在對大規模數據下非線(xiàn)性系統辨識的有效性.
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關(guān)鍵詞:
- 非線(xiàn)性系統辨識 /
- 隨機優(yōu)化 /
- 變分貝葉斯 /
- 維納模型
Abstract: Nonlinear system identification in multiple uncertain environment is an open problem. Bayesian learning has significant advantages in describing and dealing with uncertainties and has been widely used in linear system identification. However, the use of Bayesian learning for nonlinear system identification has not been well studied, confronted with the complexity of the estimation of the probability and the high computational cost. Motivated by these problems, this paper proposes a nonlinear system identification method based on stochastic variational Bayesian for Wiener model, a typical nonlinear model. First, the process noise, measurement noise and parameter uncertainty are described in terms of probability distribution. Then, the posterior estimation of model parameters is carried out by using the stochastic variational Bayesian approach. In this framework, only a few intermediate variables are used to estimate the natural gradient of the lower bound function of the likelihood function based on the stochastic optimization idea. Compared with classical variational Bayesian approach, where the estimation of model parameters depends on the information of all the intermediate variables, the computational complexity is significantly reduced for the proposed method since it only depends on the information of a few intermediate variables. To the best of our knowledge, it is the first time to use the stochastic variational Bayesian to system identification. A numerical example and a Benchmark problem of Wiener model are used to show the effectiveness of this method in the nonlinear system identification in the presence of large-scale data. -
表 1 不同子采樣數據點(diǎn)對應的參數辨識情況
Table 1 Identification of parameters corresponding to different sub-sampling data points
$ \langle \theta _0 \rangle $ $ \langle \theta _1 \rangle $ $ \langle \theta _2 \rangle $ $ \langle \theta _3 \rangle $ $ \langle \theta _4 \rangle $ $ \langle \lambda _0 \rangle $ $ \langle \lambda _1 \rangle $ $ \langle \lambda _2 \rangle $ 時(shí)間(s) 真實(shí)值 1 ?0.5000 0.2500 ?0.1250 0.0625 0 1 1 — 采樣1個(gè)點(diǎn) 1±0 ?0.5463±0.3604 0.2507±0.2471 ?0.2446±0.2655 0.0358±0.2882 0.5434±0.4180 0.6625±0.2907 0.3803±0.2185 0.6005 采樣5% 1±0 ?0.5060±0.0330 0.2693±0.0497 ?0.1252±0.0323 0.0633±0.0323 0.0908±0.2707 0.9871±0.1480 0.9103±0.1246 3.1829 采樣10% 1±0 ?0.5055±0.0248 0.2571±0.0257 ?0.1341±0.0255 0.0594±0.0256 0.0631±0.0504 0.9684±0.0498 0.9499±0.0459 7.7402 采樣20% 1±0 ?0.5077±0.0204 0.2544±0.0202 ?0.1287±0.0289 0.0659±0.0291 0.0575±0.0540 0.9813±0.0518 0.9574±0.0451 11.4620 采樣全部 1±0 ?0.5078±0.0278 0.2541±0.0283 ?0.1299±0.0271 0.0685±0.0246 0.0777±0.0726 0.9439±0.1183 0.9252±0.1326 9.0772 下載: 導出CSV表 2 不同異常值存在時(shí)的參數辨識情況
Table 2 Parameter identification when different outliers exist
$ \langle \theta _0 \rangle $ $ \langle \theta _1 \rangle $ $ \langle \theta _2 \rangle $ $ \langle \theta _3 \rangle $ $ \langle \theta _4 \rangle $ $ \langle \theta _5 \rangle $ 時(shí)間 (s) 真實(shí)值 1 ?0.5000 0.2500 ?0.1250 0.0625 ?0.03125 — 無(wú)異常值 1±0 ?0.4989±0.0292 0.2495±0.0293 ?0.1254±0.0223 0.0611±0.0257 ?0.0338±0.0262 2.9369 2% 異常值 1±0 ?0.5097±0.0389 0.2672±0.0497 ?0.1305±0.0426 0.0652±0.0452 ?0.0291±0.0494 2.9480 5% 異常值 1±0 ?0.5060±0.0330 0.2693±0.0497 ?0.1252±0.0323 0.0633±0.0323 ?0.0314±0.0523 3.1829 10% 異常值 1±0 ?0.5349±0.0325 0.2627±0.0323 ?0.1314±0.0330 0.0685±0.0389 ?0.0377±0.0355 2.9057 下載: 導出CSV表 3 不同辨識方法的性能比較
Table 3 Performance comparison of different recognition methods
$ b_0 $ $ a_1 $ $ \langle \lambda _0 \rangle(\lambda_0) $ $ \langle \lambda _1 \rangle(\lambda_1) $ $ \langle \lambda _2 \rangle(\lambda_2) $ 均方誤差 時(shí)間(s) 真實(shí)值 1 0.5 0 1 1 — — 無(wú)異常值 SVBI — — 0.0648±0.0620 0.9633±0.0509 0.9766±0.0626 0.9136 2.936 9 VBEM — — 0.0503±0.0346 0.9411±0.0393 0.9655±0.0459 0.8978 9.7046 MLE 1±0 0.5102±0.0136 0.1054±0.0405 1.0154±0.0464 0.9490±0.0411 0.9130 9.0350 PEM 1±0 0.4948±0.0172 0.0828±0.0524 0.9905±0.0373 1.0072±0.0449 0.9132 0.6474 5% 異常值 SVBI — — 0.0575±0.0540 0.9813±0.0520 0.9573±0.0450 5.4540 2.9352 VBEM — — 0.0503±0.0411 0.9770±0.0532 0.9748±0.0518 3.8695 9.7709 MLE 1±0 0.4150±0.0711 ?0.9407±0.1253 1.0019±0.1839 1.3715±0.1895 3.9574 9.6693 PEM 1±0 0.4999±0.0549 0.1072±0.1871 0.9646±0.1926 0.9878±0.1558 3.8374 0.6580 10% 異常值 SVBI — — 0.1439±0.1065 0.9163±0.0924 0.8416±0.0924 7.5364 2.9057 VBEM — — 0.0556±0.0468 0.9711±0.0538 0.9568±0.0553 5.5110 9.9245 MLE — — — — — — — PEM 1±0 0.4723±0.2004 0.1458±0.5211 0.9746±0.3091 1.0030±0.3253 5.4992 0.6620 下載: 導出CSV表 4 式(52)部分參數辨識結果
Table 4 The identification results of the part parameters of the process (52)
參數 $\theta_0$ $\theta_1$ $\theta_2$ $\theta_3$ $\theta_4$ $\theta_5$ $\theta_6$ $\theta_7$ $\theta_8$ $\theta_9$ $c_0$ $c_1$ $c_2$ $Q$ $R$ 結果值 ?0.0390 0.0648 ?0.0547 0.0856 ?0.0462 0.2613 0.0501 0.2041 0.3396 0.4154 ?0.0188 0.1035 ?0.0030 0.0034 0.0014 下載: 導出CSV表 5 不同方法的性能比較
Table 5 Performance comparison of different methods
采樣點(diǎn)數 方法 均方誤差(V) 參數個(gè)數 時(shí)間(s) 2 000 SVBI 0.056 95 25 256.12 VBEM 0.062 83 25 1 211.27 SVBI 0.034 07 40 264.27 VBEM 0.034 25 40 1 214.55 10 000 SVBI 0.061 79 25 1 299.99 VBEM 0.093 34 25 6 347.28 SVBI 0.033 85 40 1 332.31 VBEM 0.034 04 40 6 442.98 下載: 導出CSV亚洲第一网址_国产国产人精品视频69_久久久久精品视频_国产精品第九页 -
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