謝 輝,陳雙喜,馬紅杰,黃登高
(天津大學(xué)內(nèi)燃機(jī)燃燒學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室,天津 300072)
城市公交司機(jī)進(jìn)站操作特征對(duì)油耗影響分析
謝 輝,陳雙喜,馬紅杰,黃登高
(天津大學(xué)內(nèi)燃機(jī)燃燒學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室,天津300072)
針對(duì)司機(jī)駕駛操作差異影響油耗的問(wèn)題,基于遠(yuǎn)程監(jiān)控系統(tǒng)采集的天津市某公交線路超過(guò)1×105,km的實(shí)車運(yùn)行數(shù)據(jù),提取了大量司機(jī)減速行為樣本,采用曲線簇截面速度特征量提取的方法,分析了司機(jī)進(jìn)站初始速度和速度運(yùn)行區(qū)間的統(tǒng)計(jì)特征;研究了司機(jī)在同一站點(diǎn)的進(jìn)站操作特征差異對(duì)油耗的影響,并利用GT-SUITE車輛模型,仿真驗(yàn)證了倒拖制動(dòng)操作對(duì)進(jìn)站油耗的影響.結(jié)果表明:同一站點(diǎn)司機(jī)進(jìn)站初始速度符合正態(tài)分布,且減速過(guò)程存在一個(gè)狹窄的速度通道;平均倒拖時(shí)間百分比提高46.4%,進(jìn)站油耗降低12.2%;降低了倒拖結(jié)束車速,可以提高進(jìn)站燃油經(jīng)濟(jì)性.
減速行為;初始速度;倒拖時(shí)間百分比;油耗
遠(yuǎn)程監(jiān)控系統(tǒng)的統(tǒng)計(jì)數(shù)據(jù)表明,公交車行駛油耗對(duì)司機(jī)的駕駛行為和道路工況非常敏感.Shirk等[1]認(rèn)為司機(jī)操作特性是混合動(dòng)力汽車能耗影響因素中唯一的主觀因素,是所有能耗影響因素的輸入接口.Sivak等[2]研究發(fā)現(xiàn)司機(jī)的操作決策水平、激進(jìn)型駕駛風(fēng)格對(duì)輕型車輛的油耗影響達(dá)25%.de Vlieger等[3]研究發(fā)現(xiàn),在相同的道路工況、相同的車輛條件下,激進(jìn)的司機(jī)駕駛行為相比溫和的駕駛行為將增加40%的油耗,在擁擠路況下,這種差異表現(xiàn)得尤為顯著.van Mierlo等[4]研究表明,通過(guò)改變司機(jī)駕駛行為或駕駛風(fēng)格,油耗可以降低5%~25%.Sandberg[5]針對(duì)卡車司機(jī)駕駛行為的研究證實(shí),司機(jī)踩加速踏板的深淺和換擋發(fā)動(dòng)機(jī)轉(zhuǎn)速的改變,可以導(dǎo)致5%的油耗差異.Bingham[6]研究表明,在沒有任何額外駕駛?cè)蝿?wù)的前提下,不同司機(jī)駕駛測(cè)試EV轎車,凈能量損耗差別達(dá)到32%.文獻(xiàn)[7]分析公交司機(jī)的出站駕駛特征,指出瞬時(shí)油耗對(duì)加速度水平很敏感,加速度從0.5,m/s2增加至1.5,m/s2,瞬時(shí)油耗增加67%.文獻(xiàn)[8]借助Eco-Driving輔助系統(tǒng),通過(guò)交通標(biāo)志檢測(cè)技術(shù)和減速曲線最優(yōu)化算法,實(shí)現(xiàn)同一司機(jī)單次停車試驗(yàn)節(jié)油2,mL.文獻(xiàn)[9]分析了司機(jī)遇紅燈剎車行為速度曲線統(tǒng)計(jì)特征,并分析了天氣因素對(duì)剎車行為的影響.文獻(xiàn)[10]對(duì)司機(jī)安全駕駛行為進(jìn)行研究,提出了一種從司機(jī)操作數(shù)據(jù)中提取司機(jī)駕駛特征的方法.
由此可見,司機(jī)駕駛行為的研究主要在駕駛特性分類辨識(shí)、安全駕駛輔助和節(jié)油潛力評(píng)估方面.實(shí)際上,對(duì)城市公交司機(jī)而言,駕駛?cè)蝿?wù)決定了站點(diǎn)停車的要求.因此,司機(jī)進(jìn)站駕駛輔助是實(shí)現(xiàn)公交節(jié)油的有效途徑之一.
本研究通過(guò)遠(yuǎn)程監(jiān)控系統(tǒng)實(shí)時(shí)采集公交車運(yùn)行數(shù)據(jù),分析司機(jī)進(jìn)站過(guò)程統(tǒng)計(jì)特征和駕駛操作差異對(duì)油耗的影響規(guī)律,為進(jìn)站駕駛輔助提供指導(dǎo).
采用了自主開發(fā)的車輛遠(yuǎn)程數(shù)據(jù)采集裝置(簡(jiǎn)稱信息單元),如圖1所示,通過(guò)OBD(on-board diagnostics)接口實(shí)時(shí)采集車輛運(yùn)行數(shù)據(jù),通過(guò)GPS模塊獲取位置和時(shí)間信息,并利用GPRS模塊實(shí)現(xiàn)數(shù)據(jù)的遠(yuǎn)程傳輸.同時(shí),信息單元將所有數(shù)據(jù)以10,Hz的頻率同步高速記錄至SD卡.
信息單元與ECU(electric control unit)的數(shù)據(jù)交互是通過(guò)SAE J1939[11]協(xié)議實(shí)現(xiàn)的.采集的主要運(yùn)行參數(shù)包括:發(fā)動(dòng)機(jī)轉(zhuǎn)速、轉(zhuǎn)速計(jì)輸出軸轉(zhuǎn)速、發(fā)動(dòng)機(jī)實(shí)際扭矩百分比、基于車輪的車輛速度、油門踏板位置、小時(shí)燃油消耗率等.
圖1 信息單元實(shí)物Fig.1 Vehicle information unit on-board
遠(yuǎn)程數(shù)據(jù)采集及統(tǒng)計(jì)分析系統(tǒng)流程如圖2所示.①信息單元通過(guò)CAN模塊采集車輛ECU數(shù)據(jù),通過(guò)GPS模塊采集位置和時(shí)間信息;②無(wú)線網(wǎng)絡(luò)將數(shù)據(jù)發(fā)送到轉(zhuǎn)發(fā)中心;③轉(zhuǎn)發(fā)中心將數(shù)據(jù)傳輸?shù)奖O(jiān)控平臺(tái),用于車輛實(shí)時(shí)監(jiān)控;④SD卡記錄數(shù)據(jù)用于油耗統(tǒng)計(jì)分析與節(jié)油策略研究.
圖2 遠(yuǎn)程數(shù)據(jù)采集及統(tǒng)計(jì)分析系統(tǒng)流程Fig.2 Flow chart of remote data acquisition and static analysis system
研究過(guò)程中選擇了3輛相同配置的柴油公交客車,型號(hào)為ZK6902HGA,發(fā)動(dòng)機(jī)和車輛技術(shù)參數(shù)如表1所示.研究車輛運(yùn)行線路為天津市503路,全程70.4,km,平均運(yùn)行時(shí)間約160,min,從輕軌東海路站至天津西站北廣場(chǎng)站,如圖3所示.研究對(duì)象為6位男性司機(jī),基本信息如表2所示,其中,A2、B2、C2是3輛車的副班司機(jī).研究選取了2012年5月—2013年7月的運(yùn)行數(shù)據(jù),累計(jì)監(jiān)控里程超過(guò)1×105,km.
圖3 天津市503路公交運(yùn)行線路Fig.3 Tianjin city No.503 bus route
表1 發(fā)動(dòng)機(jī)和車輛技術(shù)參數(shù)Tab.1 Engine and vehicle technical parameters
表2 司機(jī)基本信息Tab.2 Driver personal information
2.1行駛里程和油耗計(jì)算
CAN(controller area network)總線獲得的原始車速數(shù)據(jù)中存在著一定的高頻噪聲,因而需要對(duì)其進(jìn)行濾波處理.濾波后車速未失真,不影響駕駛行為分析,如圖4所示.行駛里程和油耗分別通過(guò)對(duì)車速和小時(shí)燃油消耗率進(jìn)行積分,計(jì)算公式分別為
式中:L為積分里程,km;v為基于車輪的車輛速度,km/h;F為積分油耗,L;H為小時(shí)燃油消耗率,L/h;Δt為CAN總線數(shù)據(jù)更新周期,Δ,t=0.1,s.積分油耗與實(shí)際加油的油耗數(shù)據(jù)對(duì)比,驗(yàn)證了通過(guò)CAN總線獲得的油耗是可信的.
圖4 實(shí)車速度原始數(shù)據(jù)和濾波后結(jié)果Fig.4 Raw velocity data and results after filtering
2.2司機(jī)進(jìn)站片段劃分
為了分析進(jìn)站過(guò)程司機(jī)操作對(duì)油耗的影響,首先根據(jù)對(duì)實(shí)際數(shù)據(jù)的統(tǒng)計(jì),按照如下劃分條件提取進(jìn)站片段,可以最大限度地排除道路工況因素的干擾,如圖5所示,片段B和片段C不作為研究片段.
(1) 進(jìn)站過(guò)程開始時(shí)刻加速踏板開度為0,擋位為最高擋或次高擋;
(2) 進(jìn)站過(guò)程結(jié)束時(shí)刻車速為0;
(3) 進(jìn)站初始速度v0大于30,km/h;
(4) 忽略由于交通擁堵或遇紅燈造成的連續(xù)減速再加速的片段;
(5) 忽略由于交通擁堵或遇紅燈造成的中途停車片段.
圖5 進(jìn)站片段劃分示意Fig.5Segment division diagram of deceleration during bus stop
研究表明,司機(jī)主要通過(guò)當(dāng)前車速?zèng)Q策駕駛操作(加速踏板、制動(dòng)踏板和擋位).對(duì)公交車司機(jī)而言,決策進(jìn)站操作的車速是有差異的,但是站點(diǎn)位置是固定的.為簡(jiǎn)化分析起見,在滿足上述劃分條件的前提下,選擇60,m的固定進(jìn)站片段距離進(jìn)行統(tǒng)計(jì)分析.從708圈、行駛方向?yàn)檩p軌東海路站—西站北廣場(chǎng)站的駕駛試驗(yàn)樣本中,篩選了301個(gè)進(jìn)站片段,其速度曲線如圖6所示.
圖6 司機(jī)進(jìn)站速度曲線Fig.6 Driver deceleration velocity curves
從圖6直觀來(lái)看,不同司機(jī)在同一站點(diǎn)的減速過(guò)程是相似的,為了進(jìn)一步分析進(jìn)站片段統(tǒng)計(jì)特征,需要量化描述進(jìn)站過(guò)程特征.
3.1司機(jī)進(jìn)站統(tǒng)計(jì)特征
速度是描述司機(jī)進(jìn)站過(guò)程最直接、外在的參數(shù).同一站點(diǎn),各個(gè)司機(jī)面對(duì)的道路工況(天氣、乘客載荷等)的統(tǒng)計(jì)學(xué)特征在概率上是一致的.因此,在一定程度上,進(jìn)站初始速度能夠反映司機(jī)進(jìn)站過(guò)程對(duì)距離的預(yù)判經(jīng)驗(yàn)和操作習(xí)慣.對(duì)301個(gè)進(jìn)站片段進(jìn)行速度特征分析和K-S分布檢驗(yàn),進(jìn)站初始速度服從正態(tài)分布N(42.9,17.3),如圖7所示.
圖7 進(jìn)站初始車速分布Fig.7 Initial velocity histogram during bus stop
對(duì)提取的單位進(jìn)站距離橫截面的速度特征量進(jìn)行驗(yàn)證,橫截面速度均服從正態(tài)分布,得到如圖8所示的速度包絡(luò)線和各分位點(diǎn)速度曲線.其中,Q1為速度上包絡(luò)線,Q0.95和Q0.05分別為上包絡(luò)線的95%和5%位置速度曲線,Q0.5為平均值速度曲線,Q0為速度下包絡(luò)線.Q0.95和Q0.05的位置表明:同一站點(diǎn)減速過(guò)程存在一個(gè)狹窄的速度通道.
圖8 進(jìn)站速度包絡(luò)線、95%分位點(diǎn)、平均值和5%分位點(diǎn)速度曲線Fig.8 Velocity graph of envelope curve,95% quantile,median and 5% quantile curve
3.2進(jìn)站操作特征差異對(duì)油耗的影響規(guī)律
由圖8可知,不同司機(jī)進(jìn)站表現(xiàn)出相同的減速特征,但卻有不同的油耗表現(xiàn).考慮到公交投入運(yùn)營(yíng)后車輛屬性的變化,在分析司機(jī)進(jìn)站操作對(duì)油耗影響時(shí),樣本選取同一輛車的多次試驗(yàn)數(shù)據(jù),以保證駕駛試驗(yàn)的道路工況(天氣、乘客載荷等)統(tǒng)計(jì)學(xué)特征一致性.為研究司機(jī)進(jìn)站操作差異對(duì)油耗的影響,從301個(gè)進(jìn)站樣本中選擇9206號(hào)車司機(jī)B1和B2進(jìn)站過(guò)程展開分析.為排除進(jìn)站過(guò)程中由于空調(diào)開關(guān)造成油耗增加的影響,對(duì)數(shù)據(jù)進(jìn)行空調(diào)開啟校驗(yàn).
篩選的83個(gè)樣本平均車速和油耗見表3,油耗相對(duì)差異12.2%.特別說(shuō)明的是,進(jìn)站操作對(duì)油耗影響研究是在制動(dòng)踏板信息缺乏的條件下開展的.因此,只分析倒拖制動(dòng)過(guò)程對(duì)進(jìn)站油耗的影響.
表3 司機(jī)進(jìn)站過(guò)程樣本平均車速和油耗Tab.3Samples average velocity and fuel consumption of driver behavior during bus stop
根據(jù)發(fā)動(dòng)機(jī)和車輛動(dòng)力學(xué)理論,ECU對(duì)倒拖過(guò)程采取斷油策略,循環(huán)供油量為0;踩制動(dòng)的過(guò)程由于引入真空助力制動(dòng)系統(tǒng)扭矩需求,循環(huán)供油量增加.
根據(jù)對(duì)進(jìn)站過(guò)程小時(shí)燃油消耗率的初步分析,選擇倒拖時(shí)間百分比描述司機(jī)的進(jìn)站操作特征.根據(jù)統(tǒng)計(jì)節(jié)油的思路,定義進(jìn)站過(guò)程平均倒拖時(shí)間百分比Ta,其計(jì)算式為
式中:ti為第i個(gè)進(jìn)站樣本倒拖時(shí)間百分比;N為進(jìn)站過(guò)程樣本數(shù).
在83個(gè)進(jìn)站過(guò)程樣本中,司機(jī)B1和B2的平均倒拖時(shí)間百分比分別為16.75%和31.25%,相對(duì)差異為46.4%.倒拖時(shí)間百分比的分布情況如圖9所示.其中,司機(jī)B1完全不使用倒拖的樣本為12個(gè),占總進(jìn)站樣本比例為20.34%,而司機(jī)B2在所有的進(jìn)站過(guò)程中均使用倒拖制動(dòng),這反映了兩個(gè)司機(jī)進(jìn)站過(guò)程駕駛經(jīng)驗(yàn)的差異.
圖9 司機(jī)進(jìn)站過(guò)程倒拖時(shí)間百分比分布對(duì)比Fig.9Comparision of driver coast time percentage distribution of driver behavior during bus stop
司機(jī)進(jìn)站過(guò)程倒拖制動(dòng)時(shí)間的差異直接影響發(fā)動(dòng)機(jī)轉(zhuǎn)速分布的差異,如圖10所示,最優(yōu)司機(jī)是83個(gè)進(jìn)站樣本中燃油經(jīng)濟(jì)性相對(duì)最好的司機(jī).司機(jī)B2發(fā)動(dòng)機(jī)轉(zhuǎn)速分布更接近最優(yōu)司機(jī)的分布參數(shù),燃油經(jīng)濟(jì)性更好.
圖10 進(jìn)站過(guò)程發(fā)動(dòng)機(jī)轉(zhuǎn)速分布Fig.10 Engine speed distribution during bus stop
實(shí)際上,在不同的駕駛試驗(yàn)中,司機(jī)在同一站點(diǎn)的進(jìn)站過(guò)程也存在一定的差異,因此統(tǒng)計(jì)其他4位司機(jī)的進(jìn)站特征,驗(yàn)證倒拖時(shí)間百分比對(duì)油耗的影響關(guān)系.圖11所示為其他4位司機(jī)不使用倒拖制動(dòng)和使用倒拖制動(dòng)樣本的進(jìn)站平均油耗,這說(shuō)明倒拖時(shí)間百分比對(duì)進(jìn)站平均油耗的影響具有普遍性.
綜上所述,司機(jī)提高進(jìn)站過(guò)程的倒拖制動(dòng)時(shí)間百分比,可以有效降低進(jìn)站平均油耗.對(duì)司機(jī)B1和B2而言,倒拖時(shí)間百分比由16.75%提高到31.25%,相對(duì)提高46.4%,進(jìn)站平均油耗從5.47,L/(100,km)降低到4.80,L/(100,km),相對(duì)降低12.2%.因此,利用車輛動(dòng)力學(xué)的先驗(yàn)知識(shí),減少剎車操作,可以降低進(jìn)站平均油耗.
圖11 司機(jī)不使用和使用倒拖制動(dòng)的進(jìn)站平均油耗Fig.11Average fuel consumption with coast and without coast during bus stop
4.1司機(jī)進(jìn)站操作仿真模型
為模擬公交車進(jìn)站過(guò)程,搭建了涵蓋車輛模型、發(fā)動(dòng)機(jī)模型、駕駛員模型、道路模型、車輛控制和事件管理器的GT-SUITE進(jìn)站操作仿真平臺(tái),如圖12所示,該仿真平臺(tái)經(jīng)過(guò)滑行試驗(yàn)數(shù)據(jù)驗(yàn)證.
圖12 司機(jī)進(jìn)站操作優(yōu)化仿真模型Fig.12 Vehicle simulation model for deceleration driving operations optimization
4.2司機(jī)進(jìn)站倒拖結(jié)束車速分析
根據(jù)前文對(duì)進(jìn)站特征的統(tǒng)計(jì)分析,提高進(jìn)站過(guò)程倒拖時(shí)間百分比可以降低油耗.利用進(jìn)站操作仿真平臺(tái),設(shè)置不同倒拖制動(dòng)結(jié)束車速仿真案例,以驗(yàn)證倒拖結(jié)束車速對(duì)進(jìn)站油耗的影響.實(shí)車數(shù)據(jù)中司機(jī)進(jìn)站過(guò)程的倒拖制動(dòng)結(jié)束車速分布情況,如圖13所示.
仿真案例的倒拖制動(dòng)結(jié)束車速設(shè)置,如表4所示.v的設(shè)置方法為
圖13 司機(jī)進(jìn)站過(guò)程倒拖制動(dòng)結(jié)束車速分布Fig.13 Driver coast end velocity distribution features during bus stop
以進(jìn)站初始時(shí)刻擋位為5擋計(jì)算,最小倒拖結(jié)束車速為32.9,km/h,倒拖制動(dòng)結(jié)束車速vc的案例設(shè)置滿足
式中:ig為變速箱傳動(dòng)比;i0為主減速比;rw為車輪半徑;nr為發(fā)動(dòng)機(jī)恢復(fù)供油轉(zhuǎn)速.
表4 進(jìn)站過(guò)程仿真案例設(shè)置Tab.4 Simulation case setup during bus stop km/h
仿真的車速曲線如圖14所示.各個(gè)仿真案例的初始階段是相同的,目的是使車輛自由加速到穩(wěn)定狀態(tài).仿真案例減速過(guò)程的油耗分別為55.9,mL、51.6,mL和46.9,mL,折算的百公里油耗分別為5.141,L、5.072,L和4.946,L.3種不同的倒拖制動(dòng)結(jié)束速度,燃油經(jīng)濟(jì)性相差3.8%.需要特別說(shuō)明的是,仿真減速距離比實(shí)際進(jìn)站片段距離長(zhǎng),是由于仿真模型中減速過(guò)程由倒拖制動(dòng)和脫擋滑行組成.
倒拖制動(dòng)結(jié)束車速的差異,造成減速過(guò)程倒拖時(shí)間百分比和發(fā)動(dòng)機(jī)工況點(diǎn)分布的差異,如圖15所示,降低倒拖結(jié)束速度能夠充分利用減速斷油降低油耗.
圖14 仿真案例的車速-距離曲線Fig.14 Velocity-distance curves for all simulation cases
圖15 仿真發(fā)動(dòng)機(jī)工況點(diǎn)分布Fig.15 Engine operating points distribution
(1) 基于曲線簇截面速度特征量提取的方法,分析了司機(jī)進(jìn)站初始速度和速度運(yùn)行區(qū)間統(tǒng)計(jì)特征.結(jié)果表明:同一站點(diǎn)司機(jī)進(jìn)站初始速度符合正態(tài)分布,減速過(guò)程存在一個(gè)狹窄的速度通道.
(2) 分析了司機(jī)進(jìn)站過(guò)程倒拖時(shí)間百分比差異對(duì)油耗的影響.結(jié)果表明:提高進(jìn)站過(guò)程倒拖時(shí)間百分比,可以有效降低進(jìn)站平均油耗,平均倒拖時(shí)間百分比提高46.4%,進(jìn)站平均油耗降低12.2%.
(3) 利用GT-SUITE進(jìn)站操作仿真平臺(tái),分析了倒拖結(jié)束車速對(duì)進(jìn)站油耗的影響.仿真結(jié)果表明:降低倒拖結(jié)束車速,可以提高進(jìn)站燃油經(jīng)濟(jì)性.
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(責(zé)任編輯:孫立華)
Analysis on the Influence of Driver Deceleration Behavior During Bus Stop on Fuel Consumption
Xie Hui,Chen Shuangxi,Ma Hongjie,Huang Denggao
(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)
The influence of driver behavior on fuel consumption was studied. Based on 100,000 kilometers' real-time data from a Tianjin bus route,which was collected by a wireless remote monitoring system,a large amount of driver deceleration behavior samples were acquired. The study focuses on the analysis on statistical characteristics of initial velocity and speed range by adopting curve cluster driver features extraction method. Results show that the initial velocity accords with normal distribution at the same bus stop,and there exists a narrow deceleration velocity corridor. Statistical analysis on the effect of two drivers' deceleration operations difference on fuel consumption at the same stop was conducted. Fuel consumption decreased by 12.2% when average engine coast time percentage increased by 46.4%. A GT-SUITE vehicle model was built to verify the relationship between deceleration operations and fuel consumption. By reducing the coast end velocity,fuel economy can be improved.
deceleration behavior;initial velocity;coast time percentage;fuel consumption
U469.72
A
0493-2137(2015)12-1091-07
10.11784/tdxbz201403047
2014-03-15;
2014-07-02.
科技部“中日韓”國(guó)際合作基金資助項(xiàng)目(2013DFG62890).
謝 輝(1970,—),男,博士,教授.
謝 輝,xiehui@tju.edu.cn.
網(wǎng)絡(luò)出版時(shí)間:2014-09-10. 網(wǎng)絡(luò)出版地址:http://www.cnki.net/kcms/doi/10.11784/tdxbz201403047.html.