張博 李鴻 李會超
關鍵詞: 疲勞檢測; 信息融合; 圖像識別; 行為特征; 回歸分析; 模糊評價
中圖分類號: TN911.73?34; TP391 ? ? ? ? ? ? ? ? ? 文獻標識碼: A ? ? ? ? ? ? ? ? ?文章編號: 1004?373X(2019)01?0152?05
Abstract: The single or similar feature index in fatigue detection is easily disturbed, so a fatigue detection system based on multi?class feature information fusion is proposed according to the regression analysis and fuzzy evaluation theory. In accordance with the features of each fatigue characteristic, the feature parameters are described and extracted. The quantitative classification of fatigue degree is performed in combination with PVT test. The advantages of regression analysis for explaining the multivariate influence intensity and fuzzy mathematics for dealing with the uncertain problems are used to complete the design and modeling of the detection system. An optimization algorithm is proposed to overcome the interference factors in image feature extraction. The simulation experimental results show this system can detect the fatigue state of drivers effectively, and its performance is obviously improved by the optimization algorithm.
Keywords: fatigue detection; information integration; image identification; behavioral characteristic; regression analysis; fuzzy evaluation
隨著交通運輸業(yè)的迅猛發(fā)展,機動車數(shù)量急劇增加,其造成的交通事故也不斷增多。據世界衛(wèi)生組織2015年的報告,全世界每年約有125萬人死于交通事故,造成的經濟損失非常巨大。研究表明,60%左右的重大交通事故與疲勞駕駛有關[1]。因此,對疲勞駕駛檢測的研究有著非常重要的理論和現(xiàn)實意義。
目前,針對疲勞檢測這一問題主要有基于生理參數(shù)和基于行為特征兩類檢測方法。如日本Canon KK基于腦電波這一生理參數(shù),研發(fā)了一種防瞌睡裝置。文獻[2]以駕駛員對方向盤的操作行為作為突破口,設計了基于ZigBee的車載疲勞檢測方案,在不降低識別率的前提下實現(xiàn)了駕駛員疲勞狀態(tài)的快捷檢測。但此類檢測方案多采用單一的檢測指標,檢測結果的可靠性會因環(huán)境干擾而明顯降低。由Seeing Machines公司研發(fā)的Face LAB系統(tǒng)[3]則是檢測駕駛員瞳孔直徑、頭部姿態(tài)、凝視方向等多個特征信息,并進行融合分析,進一步增強了檢測結果的準確性。但因其所選特征均為圖像特征,所受干擾因素相同,檢測結果的可靠性并沒有得到明顯改善。文獻[4]在圖像信息檢測的基礎上,引入車輛軌跡分析,并采用SVM算法的數(shù)據融合模型,在一定程度上降低了圖像特征提取中干擾因素對檢測結果的影響,但車輛軌跡分析本身受路況等復雜環(huán)境影響較大,可靠性存疑。本文在融合信息檢測理念的基礎上,選取不同類別的疲勞特征,完成了疲勞度的量化分級,結合回歸分析及模糊評價理論的優(yōu)勢,設計了一套基于多類別特征的疲勞檢測系統(tǒng),有效地提高了檢測結果的可靠性和準確性。
圖4為實驗中隨機挑選的一名實驗對象的檢測數(shù)據,從圖4可以看出系統(tǒng)可以有效地反映出疲勞度與駕駛時長的關系,且經算法改進后的預測值與測量值更為接近,波動范圍明顯變小。圖5,圖6可反映出針對圖像特征提取中干擾因素的優(yōu)化算法對系統(tǒng)性能提升明顯。約定系統(tǒng)性能的評價標準為預測誤差百分比,平均絕對誤差MAE,均方根誤差RMSE,可得到系統(tǒng)性能評價如表2所示。由表2可知,改進前后的系統(tǒng)預測誤差分別為26%和19%,且改進后MAE與RMSE的降幅分別為52%與43%,預測結果的準確性和穩(wěn)定性明顯增加。由此可見,本文建立的系統(tǒng)可以有效地完成對駕駛員疲勞狀態(tài)的檢測,針對圖像特征提取中干擾因素的優(yōu)化算法對系統(tǒng)性能提升明顯。
本文通過提取不同類別的疲勞特征信息,克服了單一指標或同類信息融合指標在疲勞檢測中易受干擾這一不足。結合PVT測試完成駕駛員疲勞狀態(tài)的量化分級,綜合回歸分析與模糊評價理論各自的優(yōu)勢,完成了系統(tǒng)級別的疲勞狀態(tài)檢測方案的設計與建模,針對圖像特征提取中的干擾因素提出一種優(yōu)化算法。通過仿真實驗檢驗了系統(tǒng)性能及優(yōu)化算法的有效性。
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