CN106844922A - The engine fire fault diagnosis method with manifold learning is estimated based on cylinder pressure - Google Patents

The engine fire fault diagnosis method with manifold learning is estimated based on cylinder pressure Download PDF

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CN106844922A
CN106844922A CN201710020324.5A CN201710020324A CN106844922A CN 106844922 A CN106844922 A CN 106844922A CN 201710020324 A CN201710020324 A CN 201710020324A CN 106844922 A CN106844922 A CN 106844922A
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郑太雄
王燕军
杨新琴
杨斌
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Chongqing University of Post and Telecommunications
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Abstract

The invention discloses a kind of engine fire fault diagnosis method estimated based on cylinder pressure with manifold learning, cylinder pressure of engines is estimated using imperial Burger sliding mode observer, popular study analysis are carried out by the cylinder pressure signal estimated, to realize engine fire fault diagnosis.Crankshaft dynamic system of the present invention based on engine, it is considered to parameter perturbation present in engine mockup and uncertain problem, establishes nonlinear state equation, devises imperial Burger sliding mode observer, and cylinder pressure is accurately estimated.It is sample with the cylinder pressure signal estimated, extracting cylinder presses the temporal signatures and frequency domain character of signal, the probability distribution of samples points of its farthest is analyzed while the Neighbor Points for considering sample are distributed, during the holding projection algorithm of nearest maximum distance applied into the emulation data and actual test of engine fire state, by recognizing error rate, it was demonstrated that the algorithm is effectively diagnosed to be engine fire state.

Description

The engine fire fault diagnosis method with manifold learning is estimated based on cylinder pressure
Technical field
The invention belongs to automobile engine Misfire Fault Diagnosis method, and in particular to one kind is pressed based on cylinder and estimated and epidemiology The engine fire fault diagnosis method of habit.
Background technology
The car networking for quickly growing in recent years, is felt comprehensively using advanced intelligent comprehensive technology to road and traffic Know, realize between multiple systems on a large scale, the interaction of Large Volume Data, traffic whole-process control is carried out to each automobile, to each Bar road carries out the full-time empty control of traffic, to provide network and the application based on traffic efficiency and traffic safety.Car networking passes through Long range positioning, reads driving information, the mode such as simple fault message, gives automobile in traveling easily user's body Test, be vehicle intellectualized important component.However, when failure of the automobile in the urgent complexity of burst in travelling way, at present Car networking technology still can not well process this problem, need to by vehicle maintenance and repair enterprise carry out specialty automobile diagnosis and repair Solve.
Vehicle remote monitoring and fault diagnosis system be support vehicles safe operation, improve vehicle use reliability it is important Device.It is realized to running state of the vehicle real time on-line monitoring using new technology, new tool, grasps vehicle electrically controlling system and run number According to, carry out in advance automobile operating state data collection and analysis work, it is ensured that automobile failure generation before obtain Rational Maintenance And maintenance, all there is guidance well for automobile production manufacturer, service dealer, passenger traffic and Shipping enterprises and numerous car owners Meaning.
The purpose of onboard diagnostic system (OBD) is monitoring automobile exhaust emission system, with the development of OBD, now More and more apply in fault diagnosis, when automobile breaks down, OBD system can produce DTC, and remote diagnosis system The key data of system comes from OBD system, and teledata exchange is just carried out only when automobile breaks down, and such case is assigned not To vehicle remote monitoring.And being based on cylinder pressure most can directly recognize the related real-time status of automobile engine, in real time The related real-time status of follow-up automobile engine, for the pre- judgement and diagnosis of automobile provide strong information.
The working condition and failure of gasoline engine greatly can be bent with the change of time (or crank angle) by cylinder pressure Line is reflected.Typically manual type is taken to judge the working condition of gasoline engine, i.e., with the experience combination gasoline engine of people Work phenomenon judges, such as smoke evacuation, temperature, power output, noise.And some reflection gasoline engine working conditions parameter then without Method direct access, such as can most reflect the cylinder pressure of gasoline engine work and technology status, in the status monitoring and failure of gasoline engine It is one of best index of sign gasoline engine running status in diagnosis.Gasoline engine cylinder pressure indicator card is that description gasoline is motor-driven The basic means of power performance, its concentrated expression gasoline engine exports the heating power transfer process of mechanical work.The cylinder pressure of gasoline engine Estimation and analysis for improve gasoline engine service behaviour, carry out the optimal IGNITION CONTROL of gasoline engine or oil injection time control, row Putting control and condition monitoring and fault diagnosis all has very important effect.
From the nineties in 20th century, the research and development of automobile engine Misfire Fault Diagnosis method is rapid, has emerged and has been permitted Many new methods.Cylinder is lighted a fire successfully each time, and engine can obtain power input, and then cause engine speed fluctuations.Such as Fruit ignores inertia torque, load torque, friction torque and pumping moment of torsion, then each angular velocity fluctuation and combustion powered generation Waveform will be directly related, and research velocity variations can provide a kind of method of detection of catching fire.Theoretically, any exception Failure will reflect in variance causes the change of speed, acceleration or torque.Therefore, the variance or acceleration of research speed can be with Cylinder pressure based on crankshaft speed is provided and estimates method for diagnosing accidental fire.Because crankshaft speed measuring method is simple, so bent axle Instantaneous angular velocity is that current most widely used one kind is caught fire basis for estimation, for the instability problem of angular velocity of crankshaft.Compare In bent axle instantaneous angular velocity, bent axle intermittent angle acceleration ratio angular velocity of crankshaft more can directly reflect the real work operation of engine State, due to including the prompting message for catching fire in angular acceleration, preferably mistake is can obtain by suitable feature extracting method Fiery signal.Because crank torque is unable to direct measurement, generally obtained using indirect estimation methods, some documents set up single cylinder respectively With the engine mockup of multi-cylinder, using the method for parameter Estimation, estimating to the conjunction moment of torsion of cylinder torque and friction torque is realized Meter, the positioning of caught fire to multicylinder engine judgement and the cylinder that catches fire.These method low costs, advantages of simple structure and simple.Some texts Offer have studied and catch fire to waste gas, cylinder pressure variation track, indicate average effective moment of torsion, rate of heat release and combustion phase module Influence, experiment discovery most vat presses the change of corresponding crank angle and burning initial parameters to the no effect of detection of catching fire, and The cylinder buckling of different crank angles has very strong correlation with generation of catching fire at top dead centre, and then utilizes ANN Network, for the detection of hcci engine misfire fault, with precision very high.Cylinder pressure can not only inline diagnosis engine Catch fire and the abnormal combustion phenomenon such as pinking, engine transient air-fuel ratio, time of ignition, waste gas can also be realized by cylinder pressure The control of the engines such as recycling (EGR).Above-mentioned method is summarized by comparing, based on the engine fire failure that cylinder pressure is estimated Diagnosis is sensitiveer, more easily a kind of method.Due to not needing any optional equipment, it is allowed to have wide in misfire diagnosis Prospect.
The content of the invention
Estimated based on cylinder pressure and the popular engine fire fault diagnosis for learning it is an object of the invention to provide a kind of, Measurement according to engine speed provides a kind of accurate, inexpensive reliable method to obtain the state of engine, reaches hair The purpose of motivation on-line fault diagnosis.
The present invention is adopted the following technical scheme that to achieve these goals:
Engine fire fault diagnosis method with manifold learning is estimated based on cylinder pressure, is comprised the following steps:
1) engine is analyzed by cylinder Mathematical Modeling, and engine is set up in the form of the differential equation by cylinder model, It is expressed as:
Wherein, ApRepresent cylinder piston area, LtorThe effective arm of force of the cylinder pressure to axial line is represented, p represents cylinder pressure Power, R represents crank throw, and ω represents angular velocity of crankshaft, TL(θ) represents total resistive torque, Tl(θ) represents the load of engine Moment of torsion, J (θ) represents bent axle instant rotation inertia, and V represents cylinder total volume,Fuel combustion heat release rate is represented,Table Show crankshaft accelerations,The derivative of pressure is represented, α represents scattering losses' proportionality coefficient, m1Represent piston mass and connecting rod quality it With, γ specific heat ratios,Represent that cylinder controls the derivative of volume.WhereinL is Length of connecting rod.
2) sliding mode theory is utilized, cylinder pressure dragon Burger sliding mode observer is set up by cylinder model with reference to engine, be expressed as:
Wherein,The observation of cylinder pressure is represented,It is observation error, imperial Burger gain parameter L=(l1 l2)T, sliding formwork gain parameter K=(k1 k2)T,RepresentObservation, TrIt is inertia torque, Tf It is friction torque, TlIt is load torque.
It is suitable by using the opinion design of Lyapunov stability theorems in above-mentioned imperial Burger sliding mode observer Luenberger gain parameters, make the Luenberger tracking velocity that can accelerate state estimation, make the sliding formwork can be fine Related uncertainty and disturbance in ground processing system, while making designed observer error system stable convergence.In order that Observer can overcome parameter perturbation present in model and uncertainty, and processing parameter disturbance is added in sliding mode observer And probabilistic sliding formwork.
3) using imperial Burger sliding mode observer, the cylinder pressure to cylinder compression stroke and working stroke is observed, and surveys Take cylinder pressure signal.Under the different rotating speeds of each misfire fault type of simulated engine, including, normal condition, a cylinder catch fire former Barrier, a two cylinder misfire fault and one or four cylinder misfire faults, every kind of Status Type devise again 800r/min, 1200r/min, Operating condition under 2000r/min rotating speeds.The cylinder pressure signal of each Status Type under every kind of rotating speed and idle condition is measured, altogether 12 groups of cylinder pressure signals are obtained, sampling number is 68400, and the time is 12s.
4) temporal signatures and frequency domain character of cylinder pressure signal are extracted, using the holding projection algorithm of nearest maximum distance Fusion time domain index and frequency-domain index form the transition matrix that low-dimensional feature space training sample and higher-dimension map to lower dimensional space.
5) the current cylinder pressure signal of collection engine, builds corresponding higher-dimension test sample, by higher-dimension test sample The transition matrix mapped with higher-dimension to lower dimensional space is combined obtains low-dimensional test sample space, then by recognizing clustering method (ginseng See reference document [1]) the misfire fault state that determines belonging to test sample.
The time domain index includes square average pa, kurtosis pq, average paver, degree of skewness ppx, peak value pm, square amplitude prms、 Waveform index k, peak index k2, pulse index k3With margin index k4;Frequency-domain index includes 0.5 rank amplitude, 1 rank amplitude, 1.5 Rank amplitude and 2 rank amplitudes.
The calculating process of the holding projection algorithm of the nearest maximum distance is as follows:
(1) Neighbor Points and the solstics of the temporal signatures and frequency domain character extracted from cylinder pressure are calculated:Calculate each Sample point piWith the Euclidean distance between remaining sample point, its nearest k is found outn(pi) individual sample point and farthest kl(pi) individual sample This point, constructs neighbour's matrix samples and farthest matrix samples respectively;
(2) weighted value is selected according to following formula to neighbour's matrix samples, obtains the weight matrix W ∈ O of neighbour's matrix samplesN×N, N is sample number, and O represents sample space set;T is thermonuclear parameter, WigRepresent The weight matrix of nearest samples.
(3) weighted value is selected according to following formula to farthest matrix samples, obtains the weight matrix S ∈ O of farthest matrix samplesN×N
T is thermonuclear parameter, SigRepresent the weight square of maximum distance sample Battle array.
(4) characteristic vector of transition matrix A is calculated according to following formula
PZPTA=κ PDPTA
In formula, D is diagonal matrix, is metAnd Z=D-W+S. κ represent the characteristic value of transition matrix, P Represent sample matrix.A is transition matrix, A=(a1,a2,…,ad)。
(5)a1,a2,…,adIt is characterized value κ1<…<κdCorresponding characteristic vector, d is the intrinsic dimensionality for extracting, d<M, low-dimensional The sample in space is yi=ATpi
In order to extract the status information of engine, intelligent diagnostics function is realized, randomly select the sample of total number of samples 60% use Nearest maximum distance keeps projection algorithm to be trained, and remaining sample is used to test, and uses 1 arest neighbors 1NN[1](1- Nearest Neighbor) the identification error rate that is calculated of sorting algorithm.
Based on above method, the present invention has advantages below:
(1) based on engine cylinder pressure kinetic model, for the convergence time problem that engine cylinder pressure is estimated, The present invention devises Luenberger sliding mode observers, and designing observer by Lyapunov Theory of Stability and sliding mode theory increases Beneficial parameter, realizes the accurate estimation to cylinder pressure.
(2) the NFDPP algorithms of projection are kept to consider the near of each sample point simultaneously based on arest neighbors and farthest sample distance Adjacent matrix and farthest matrix, may be such that the sample after dimensionality reduction can preferably retain the structural information of initial data.
(3) engine information that is easily obtained by the indirect method of measurement estimates cylinder pressure, due to low cost, simple structure The advantages of, the indirect method of measurement can write direct ECU, can be the assistance in terms of OBD sets up on-line monitoring or diagnosis.
Bibliography
[1] .2 editions Beijing of Bian Zhaoqi, Zhang Xuegong pattern-recognitions [M]:Publishing house of Tsing-Hua University, 2000.
Brief description of the drawings
Fig. 1 is crank-connecting rod mechanism for engine;V in figurecIt is combustion chamber volume, VsIt is displacement, VdIt is engine Discharge capacity, D is piston diameter, αθIt is connecting rod angle, θ is crank angle, and l is length of connecting rod, and R is crank throw, and h is piston row Journey, TDC (Top Dead Center) is top dead centre, and BDC (Bottom Dead Center) is lower dead center;
Fig. 2 is the schematic diagram that observer estimates cylinder pressure;
Fig. 3 is Luenberger sliding mode observer structure charts;
Fig. 4 is in engine failure identification process figure;
Fig. 5 is the estimation effect analogous diagram of present invention cylinder pressure under normal circumstances;
Fig. 6 is the estimation effect analogous diagram in the case of failure of the present invention.
Specific embodiment
It is of the present invention to be estimated based on cylinder pressure and the popular engine fire fault diagnosis method for learning, using imperial Burger (Luenberger) sliding mode observer estimates that cylinder pressure of engines the measurement according to engine speed provides a kind of accurate, The reliable method of low cost obtains the state of engine.In the lab, the cylinder pressure that is proposed estimate model be Carried out in four cylinder SI engines, comprised the following steps that:(in the present inventionRepresent the derivative form of the variable, symbol ∧ tables Show the observation implication of the variable, the error of symbol~the represent variable observations and actual value).
1) engine is by cylinder modelling
Angular velocity of crankshaft information is extremely important for engine interior condition monitoring, be engine control or diagnostic application most Frequently system mode, crankshaft dynamic model such as Fig. 1 that the present invention sets up.Cylinder pressure observer needs cylinder pressure The two systems state of power kinetic model, measurable transient state angular velocity of crankshaft and immesurable cylinder pressure, angular velocity of crankshaft Information is highly useful for the monitoring of engine interior state, be engine control and the most frequent system mode of diagnostic application it One, it is considered to friction torque Tf, load torque Tl, bent axle inertia non-linear dynamic model can be represented by the following formula
Wherein ω is angular velocity of crankshaft, and θ is crank angle, JeIt is effective total rotary inertia of engine, indication torque is Tind, TrIt is inertia torque:
Tind=tPLtor=ApLtorp
Here p, ApAnd LtorThe respectively effective arm of force of cylinder pressure, piston area and pressure to axial line;tPRepresent gas Body pressure value.
Ap=π D2/4
Wherein, l is length of connecting rod, and R is crank throw, and D is piston diameter.
TrIt is by rotating and moving back and forth the inertia torque for producing, i.e.,(m in formula1 Represent piston mass and connecting rod quality sum, trRepresent reciprocal inertia force,
To sum up to the analysis of engine, the crankshaft dynamic model for engine is arranged:
In formula, TL(θ) is to represent total resistive torque, and J (θ) is rotary inertia in bent axle equal set.
Assuming that each cylinder load is identical, the pressure, temperature between such cylinder and cylinder are consistent, cylinder pressure power Learning model can be described by monomer thermodynamics burning equation, can be write as:
V represents volume of cylinder,The derivative of cylinder pressure is represented, γ represents specific heat ratio, V·Represent the derivative of volume of cylinder, p Cylinder pressure is represented, α represents scattering losses' proportionality coefficient.
Fuel combustion heat release rateFor:
It is fuel firing rate, generally all uses empirical equation weber (wiebe) function representation, i.e.,
Wherein here mfRepresent the fuel oil quality of injection, QLHVFuel low heating value, the fuel low heating value of gasoline is QLHV= 43.448MJ/kg, in formula, n is efficiency parameters, and m is form factor, θ0It is burning starting point, △ θ are combustion duration.
Engine is done manual work the stage, and in the presence of cylinder pressure, piston is from top dead centre (TDC) to lower dead center (BDC) It is mobile, and promote bent axle to rotate acting by connecting rod.In this process, the displacement y of pistonpThe angle, θ rotated with bent axle Relation is as follows:yp=R (1-cos θ)+l (1-cos αθ), l represents length of connecting rod, αθRepresent link angle.
Cylinder total volume V is by displacement VsWith combustion volume VcComposition, i.e. V=Vs+Vc, wherein combustion volume is: Vc=pD2S/ (4 (r-1)), s is piston stroke, and r is compression ratio, so
To sum up to the analysis of engine crankshaft dynamic model and engine cylinder pressure model, engine can be obtained It is by cylinder model:
2) cylinder pressure based on Luenberger sliding mode observers is estimated
Can be deduced by cylinder model by 1) obtaining engine, we can obtain engine nonlinear state system:
Through analysis, from observability order criterion, system is observable.In order that during observer can overcome model The parameter perturbation and uncertainty of presence, and the tracking velocity of state estimation is improved, the observer structure such as Fig. 3 is given to system Thinking is made, Luenberger sliding mode observers are devised, Luenberger sliding mode observers include two parts:Accelerate tracking speed Luenberger of degree and processing parameter disturbance and probabilistic sliding formwork.First to engine Nonlinear System Design Luenberger sliding mode observers are as follows:
Wherein,It is state x observations, L=(l1 l2)TIt is Luenberger gain parameters.X=(ω p)T,C=(1 0), wherein A11=0,A21=0, B1=0,
In order that the Luenberger tracking velocity that can accelerate state estimation, defining observation error isBy The error that above formula can obtain system is:Known by Lyapunov stability theorems, if (A-LC) is Hurwitz matrixes, the i.e. real part of the characteristic value of (A-LC) are negative, then systematic errorIt is asymptotically stability.Secondly, in order that seeing Survey device can uncertain and parameter perturbation present in processing system, obtained for Luenberger observers addition sliding formwork Luenberger sliding mode observers:
Wherein K=(k1 k2)TIt is sliding formwork gain parameter, cylinder pressure can be obtained by cylinder model with reference to engine Luenberger sliding mode observers are as follows:
WhereinSystematic error can be obtained by contrasting us is:
Wherein, Crankshaft speed error derivative is represented,Cylinder pressure error derivative is represented,Table Show cylinder pressure, L=(l1 l2)TIt is imperial Burger (Luenberger) gain parameter, sliding formwork gain parameter K=to be designed (k1 k2)T
Define sliding-mode surfaceBefore sliding-mode surface is reached, known by sliding mode theory:
Then
When engine speed estimate convergence actual value, that is, when reaching sliding-mode surface,ThenAndAs available from the above equation:
Above formula is updated in systematic error formula can be obtainedMakeAsymptotic convergence to zero, it is necessary toI.e.When piston moves to TDC (top dead centre) nearby, by its matrix Differentiate that battle array understands that cylinder pressure is unobservable, should now close sliding formwork gain k, only Luenberger in cylinder pressure observer Gain L portion is modified to pressure.
Coupled what experiment porch was built with the engine of real vehicle based on Luenberger sliding mode observers, and be given Observer estimates explanatory diagram directly perceived such as Fig. 2 of cylinder pressure, is taken using information such as the distributive values, crank angle obtained from real vehicle Cylinder pressure state equation is built, the variable information design gas in the information such as distributive value, crank angle and state equation is recycled Cylinder pressure observer, so as to obtain cylinder pressure observation.Such as Fig. 5 and Fig. 6, the cylinder pressure estimation respectively under normal condition The cylinder pressure estimate for being worth and catching fire under state, it can be seen that the impact of misfire fault substantially with normal condition under It is significantly different, its amplitude in the case of catching fire and under normal circumstances different.
3) projection algorithm (Nearest and farthest distance preserving are kept based on farthest recently Projections NFDPP) engine fire state recognition, the cylinder pressure signal of engine includes abundant information, Change, the impact of piston of rotating speed and cylinder pressure can effectively be reflected, engine condition prison is carried out using cylinder pressure signal Survey and fault diagnosis has signal acquisition is easy, operation strategies are wide etc..Misfire fault directly causes engine operational cycle to occur Change so that the exciting force frequency of engine becomes the other cycle.Such as, a cylinder catches fire can destroy the flat of engine operation Weighing apparatus, the exciting force that remaining cylinders are produced constitutes the other cycle, also occurs accordingly from the frequency spectrum of the cylinder pressure signal estimated Change, similarly, when two adjacent cylinder occurring or being separated by two cylinders and catches fire, the frequency spectrum of cylinder pressure signal will also change.As schemed 4, we study the cylinder pressure signal in the case of engine failure, extract corresponding feature, and each spy is merged using manifold learning Levy index and form the transformation model that low-dimensional feature space training sample and higher-dimension map to lower dimensional space, then estimate present engine Cylinder pressure signal, and build corresponding higher-dimension sample space, higher-dimension sample space and Mapping and Converting models coupling are obtained Corresponding low-dimensional sample space, by recognizing clustering method[1]Determine the current state of sample estimates.Simulated engine each Status Type, Status Type is:Normal condition, a cylinder misfire fault, a two cylinder catch fire and one or four cylinder misfire faults, every kind of state Type devises the operating condition under 800r/min, 1200r/min, 2000r/min rotating speed again.Measure every kind of rotating speed and unloaded work The cylinder pressure signal of each type fault under condition, is obtained 12 groups of cylinder pressure signals, and sampling number is 68400, and the time is 12s.For the data matrix for actually obtaining, the input sample matrix P of manifold learning is obtained by calculating various features index, removed Calculate each sample point piNeighbour's sample relation outside, NFDPP algorithms also contemplate the sample away from the farthest of the sample point This structural information, that is, algorithm realizes the calculating of maximum distance.Feature space after dimensionality reduction can more fully retain original Beginning data matrix design feature.Here is that NFDPP algorithms realize step, sample P={ p1,p2,…,pN}∈Rm×NWherein m=14 Number is characterized, N=120 is sample number:
(1) Neighbor Points and solstics are calculated:Calculate each sample point piWith the Euclidean distance between remaining sample point, find out Its nearest kn(pi) individual sample point and farthest kl(pi) individual sample point, construct neighbour's matrix samples and farthest matrix sample This.Range formula is:
d(pi,pj)=| | pi-pj||
pi, pjThe sample point of different cylinder pressure characteristics is represented respectively
(2) weighted value is selected according to following formula to neighbour's matrix samples, obtains the weight matrix of neighbour's matrix samples
W∈ON×NT is thermonuclear parameter, WigRepresent nearest
The weight matrix of adjacent sample
(3) because traditional LPP (Locality Preserving Projection) algorithm only studies its neighbour's sample Structure and have ignored farthest sample information.For the problem, while NFDPP algorithm research nearest samples, it is considered to farthest sample This structural information, weighted value is selected according to following formula, obtains the weight matrix S ∈ O of farthest matrix samplesN×N
T is thermonuclear parameter, SigRepresent the weight square of maximum distance sample Battle array
(4) characteristic vector of transition matrix A is calculated according to following formula
PZPTA=κ PDPTA
In formula, D is diagonal matrix, is metAnd Z=D-W+S.P represents cylinder pressure characteristics data square Battle array.
(5) characteristic value and characteristic vector in calculation procedure (4), vector a1,a2,…,adAs characteristic value κ1<…<κdIt is right The characteristic vector answered, d is the intrinsic dimensionality for extracting, d<m.Therefore, the sample of lower dimensional space is yi=ATpi, wherein A is conversion square Battle array, A=(a1,a2,…,ad)。
In order to extract the status information of engine, intelligent diagnostics function is realized, randomly select the sample of total number of samples 60% For training, remaining sample is used to test, and the identification mistake being calculated using 1NN (1-Nearest Neighbor) method Rate.1NN has the advantages that algorithm is simple, parameter setting is few, is one of method of calculating identification error rate more conventional at present. We are in the time domain beamformer of analog result as can be seen that for same state, the amplitude of its time domain is with the increasing of rotating speed Plus and increase, the impact of misfire fault is substantially different from normal condition, the cylinder pressure that cylinder that a cylinder catches fire pressure signal and two cylinders catch fire The amplitude of signal is different, and two cylinders of different order catch fire, and its cylinder pressure signal is also what is differed.From corresponding spectrogram we It can also be seen that engine is under each state, the amplitude that engine turns at 2 times of frequency f is maximum, for misfire fault, goes out The inapparent frequency 0.5f of normal condition, the amplitude of 1.5f are showed.During due to certain cylinder misfire of engine, destruction engine fortune Capable balance, makes engine remaining cylinders gas blow-through exciting force constitute another period of change, so 0.5f is occurred in that, f, 1.5f Frequency content.So the cylinder pressure signal estimated by more than is uniformly divided into 10 sections, and the analytical calculation time domain index according to more than: Square average pa, kurtosis pq, average paver, degree of skewness ppx, peak value pm, square amplitude prms, waveform index k, peak index k2, pulse Index k3, margin index k4, frequency-domain index:0.5 rank amplitude, 1 rank amplitude, 1.5 rank amplitudes, 2 rank amplitudes, totally 14 indexs.Finally Obtain 14 × 120 sample matrix.By to real vehicle Platform Analysis, in time domain waveform, the impact amplitude of misfire fault is obvious Under more than normal condition, in the spectrogram of frequency domain, it can be seen that appear in what normal condition did not had in the case of misfire fault The frequency content of 0.5f, f, 1.5f.By experimental analysis, when our training samples are 72 (equivalent to the 60% of total sample), low When dimension dimension is 2~10, farthest recently to keep projection algorithm to obtain preferable recognition effect, minimum identification error rate is 0. NFDPP algorithms are due to while consider the nearest and farthest structural information of sample data so that the sample after dimensionality reduction can be more Ground retains the distributed intelligence of initial data, obtains more preferable recognition result.Due to have on engine engine speed sensor and Camshaft-signal sensor, the then engine fire fault diagnosis algorithm estimated based on cylinder pressure can write direct ECU, by estimating gas Cylinder pressure is analyzed, and the assistance in terms of on-line monitoring or diagnosis can be set up for OBD.

Claims (6)

1. the engine fire fault diagnosis method with manifold learning is estimated based on cylinder pressure, it is characterised in that:Comprise the following steps:
1) engine is analyzed by cylinder Mathematical Modeling, and engine is set up in the form of the differential equation by cylinder model, represented For:
&omega; &CenterDot; = A p L t o r p - m 1 RL t o r g ( &theta; ) &omega; 2 - T L ( &theta; ) J ( &theta; ) p &CenterDot; = - &gamma; V V &CenterDot; + &gamma; - 1 V ( 1 - &alpha; ) Q &CenterDot; c h
Wherein, ApRepresent cylinder piston area, LtorThe effective arm of force of the cylinder pressure to axial line is represented, p represents cylinder pressure, R Crank throw is represented, ω represents angular velocity of crankshaft, TL(θ) represents total resistive torque, and J (θ) represents bent axle instant rotation inertia, V represents cylinder total volume,Fuel combustion heat release rate is represented,Represent crankshaft accelerations,Represent the derivative of pressure, α Represent scattering losses' proportionality coefficient, m1Expression piston mass and connecting rod quality sum, γ specific heat ratios,Represent cylinder control volume Derivative;WhereinL is length of connecting rod;
2) sliding mode theory is utilized, cylinder pressure dragon Burger sliding mode observer is set up by cylinder model with reference to engine, be expressed as:
&omega; &CenterDot; = 1 J ( &theta; ) A p L t o r p ^ - f ^ ( t ) + l 1 &omega; ~ + K s i g n ( &omega; ~ ) p &CenterDot; = - &gamma; V V &CenterDot; p + &gamma; - 1 V ( 1 - &alpha; ) Q &CenterDot; c h + l 2 &omega; ~ + k 2 s i g n ( &omega; ~ )
Wherein,The observation of cylinder pressure is represented,It is observation error, imperial Burger gain parameter L=(l1 l2)T, it is sliding Mould gain parameter K=(k1 k2)T
3) using imperial Burger sliding mode observer, the cylinder pressure to cylinder compression stroke and working stroke is observed, and measures gas Cylinder pressure signal;
4) temporal signatures and frequency domain character of cylinder pressure signal are extracted, is merged using the holding projection algorithm of nearest maximum distance Time domain index and frequency-domain index form the transition matrix that low-dimensional feature space training sample and higher-dimension map to lower dimensional space;
5) the current cylinder pressure signal of collection engine, builds corresponding higher-dimension test sample, by higher-dimension test sample and height The transition matrix combination for tieing up lower dimensional space mapping obtains low-dimensional test sample space, then by recognizing that clustering method determines test Misfire fault state belonging to sample.
2. the engine fire fault diagnosis method with manifold learning, its feature are estimated based on cylinder pressure according to claim 1 It is:The time domain index includes square average pa, kurtosis pq, average paver, degree of skewness ppx, peak value pm, square amplitude prms, waveform Index k, peak index k2, pulse index k3With margin index k4;Frequency-domain index includes 0.5 rank amplitude, 1 rank amplitude, 1.5 rank width Value and 2 rank amplitudes.
3. the engine fire fault diagnosis method with manifold learning, its feature are estimated based on cylinder pressure according to claim 1 It is:The calculating process of the holding projection algorithm of the nearest maximum distance is as follows:
(1) Neighbor Points and solstics are calculated:Calculate each sample point piWith the Euclidean distance between remaining sample point, it is found out most Near kn(pi) individual sample point and farthest kl(pi) individual sample point, neighbour's matrix samples and farthest matrix samples are constructed respectively;
(2) weighted value is selected according to following formula to neighbour's matrix samples, obtains the weight matrix of neighbour's matrix samplesT is thermonuclear parameter, WigRepresent the weight of nearest samples Matrix;
(3) weighted value is selected according to following formula to farthest matrix samples, obtains the weight matrix S ∈ O of farthest matrix samplesN×N
T is thermonuclear parameter, SigRepresent the weight matrix of maximum distance sample;
(4) characteristic vector of transition matrix A is calculated according to following formula
PZPTA=κ PDPTA
In formula, D is diagonal matrix, is metAnd Z=D-W+S. κ represent the characteristic value of transition matrix, P is represented Cylinder pressure characteristics data matrix;A is transition matrix, A=(a1,a2,…,ad);
(5)a1,a2,…,adIt is characterized value κ1<…<κdCorresponding characteristic vector, d is the intrinsic dimensionality for extracting, d<M, lower dimensional space Sample be yi=ATpi
4. the engine fire fault diagnosis method with manifold learning is estimated based on cylinder pressure according to claim 1 or 2 or 3, It is characterized in that:Step 3) also under the different rotating speeds including each misfire fault type of simulated engine, estimate every kind of rotating speed and sky The cylinder pressure signal of each Status Type under load operating mode.
5. the engine fire fault diagnosis method with manifold learning, its feature are estimated based on cylinder pressure according to claim 4 It is:The engine fire fault type includes, normal condition, a cylinder misfire fault, a two cylinder misfire fault and one or four cylinders Misfire fault.
6. the engine fire fault diagnosis side of estimation and manifold learning is pressed according to claim 1 or 2 or 3 or 5 based on cylinder Method, it is characterised in that:Also include calculating identification error rate using 1NN methods.
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