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    • 专利摘要:
    A method for determining a change in air resistance felt by a motor vehicle as its distance to a lead vehicle travelling ahead of the motor vehicle changes, wherein said motor vehicle comprises an engine for transmission of a driving force to at least one driving wheel. The method comprises. a) detecting a distance to said lead vehicle and storing data relating thereto, b) determining the driving force transmitted by the engine and storing data relating thereto, c) estimating a driving resistance felt by the vehicle and storing data relating thereto,wherein steps a-c are carried out at least on a first occasion and on a second occasion, between which occasions the distance to the lead vehicle has changed. It further comprises the step: d) based on said stored data relating to the detected distance, the driving force, and the driving resistance, estimating a change. in air resistance felt by the vehicle related to a change in the distance to the lead vehicle.(Fig. 2)
    公开号:SE1551395A1
    申请号:SE1551395
    申请日:2015-10-29
    公开日:2017-04-30
    发明作者:Oremus Bas；Ögren Mikael；Roos Fredrik；Flärdh Oscar
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    A method for determininq a chanqe in air resistance felt bv amotor vehicleTECHNICAL FIELD OF THE INVENTIONThe present invention relates to a method for determining achange in air resistance felt by a motor vehicle according to thepreamble of claim 1. The invention further relates to a computerprogram, a computer program product, an electronic control unit,and a motor vehicle. By a motor vehicle is here intended a vehiclewhich is powered by an internal combustion engine and/or by anelectric motor. ln particular, but not exclusively, the method isintended for use in a heavy motor vehicle such as a truck or a bus.
    BACKGROUND AND PRIOR ARTThe cost of fuel for motor vehicles, e.g. cars, trucks and buses,represents a significant expense for the owner or user of thevehicle. A wide variety of different systems have therefore beendeveloped for e.g. fuel-efficientreducing fuel consumption,engines and fuel-economising cruise controls.
    One of the main factors affecting the energy consumption of avehicle, in particular at high speeds and for large motor vehicleshaving a large front area, is air resistance. A way to reduce the airresistance, and thereby the energy consumption, is therefore todrive behind a lead vehicle and exploit the so called slipstreameffect. When two or more vehicles are involved in a so-calledconvoy, i.e. when trailing vehicles drive relatively proximate tolead vehicles, the fuel consumption of said vehicles can bereduced by, for example, 5-15%.
    Modern motor vehicles can be equipped with radar technology tomeasure a distance to a lead vehicle. Some vehicles can also beequipped with a control system to automatically maintain adistance, chosen by a driver, to a lead vehicle. According to oneexample, such a system can comprise an actuating device withwhich the driver can manually set a position that corresponds to agiven gap to a lead vehicle. Such an actuating device can e.g.have five different positions that correspond to discrete incrementsof distance to the lead vehicle between 10 and 75 meters,corresponding to time gaps within the range of 1-4 seconds. Thissystem is usually automated in the trailing vehicle. Alternatively, adriver of the trailing vehicle can choose to drive at a given distanceto the lead vehicle.
    For a driver of a motor vehicle, or a haulage company owning thevehicle, it is of interest to know how the energy consumption of thevehicle is affected by the driving pattern. For example, it is ofinterest to know how the energy consumption can be influenced byvarying the distance to a lead vehicle travelling ahead of thevehicle, so that the distance can be controlled to an optimumdistance from an energy consumption point of view.
    WO2013/147682 discloses a method for adapting the speed of amotor vehicle such that it travels at a distance from a lead vehiclewhich is optimised for reducing the air resistance felt by thevehicle. Factors such as a front area and a load configuration ofthe lead vehicle, the present speed of the vehicle, and winddirection and wind force of the ambient air are taken into account.the methodparameters for determining the air resistance felt by the vehicle,However, requires knowledge of many inputwhich parameters may not always be readily available.
    SUMMARY OF THE INVENTIONlt is a primary objective of the present invention to achieve an, inat least some aspect, improved way of determining a change in airresistance felt by a motor vehicle as a lead vehicle travelling aheadof the motor vehicle is detected and as its distance to said leadvehicle changes. ln particular, it is an objective to achieve asimplified way of determining such a change, which can beperformed also with few input parameters.
    According to a first aspect of the present invention, at least theprimary objective is achieved by means of the method initiallydefined, which is characterised in that it comprises the steps:a) detecting a distance to said lead vehicle and storing datarelating thereto,b) determining the driving force F_driving transmitted by theengine and storing data relating thereto,c) estimating a driving resistance F_res felt by the vehicle andstoring data relating thereto,wherein steps a-c are carried out at least on a first occasion andon a second occasion, between which occasions the distance tothe detected lead vehicle has changed, and wherein the methodfurther comprises the step:d) based on said stored data relating to the detected distance,the driving force F_driving, and the driving resistance F_res,estimating a change in air resistance felt by the vehiclerelated to a change in the distance to the lead vehicle.
    The method according to the present invention relies on anestimation of the driving resistance F_res affecting the vehicle anda measurement of the driving force F_driving transmitted by theengine on at least two different occasions to determine a changein air resistance felt by the vehicle between those occasions, e.g.to estimate a slipstream effect. The change in air resistance thatdepends on a change in distance to a lead vehicle is hereinafteralso referred to as an inter-vehicle distance dependent change inair resistance. This is a way of estimating a change in airresistance which requires few input parameters and which cantherefore be applied in many different vehicles. The driving forceis usually well known since this may, according to prior art, becalculated straightforwardly with the use of the torque emitted bythe combustion engine. This torque is usually specified in thevehicle's control system. With the use of gear ratio and wheeldiameter, the torque can be converted into a driving force actingon the vehicle's driving wheels.
    The driving resistance felt by the vehicle during operation, i.e. theresultant of the forces impacting the vehicle, can be estimated inmany different ways and taking different terms into accountdepending on the desired accuracy of the estimation. For example,a simple model of the driving resistance used in the methodaccording to the invention may include terms describing a totalforce F_tot acting on the vehicle and a gravitational force F_grav,and an error term F_error. ln this case, all forces that vary, suchas roll resistance, air resistance etc., are included in the errorterm. Also a possible slipstream effect will be included in this term,and by determining how F_error varies with the inter-vehicledistance, it is possible to roughly estimate the slipstream effect.For better accuracy, the model may include terms describing e.g.a total force F_tot, a gravitational force F_grav, a rolling resistanceforce F_roll, an air resistance force F_air, and a force F_pt due tofrictional losses in a powertrain of the vehicle. A separate modelmay be included for each of those terms. According to theinvention, an inter-vehicle distance dependent air resistance maybe included as a separate slipstream term F_slipstream in such amodel, or included in a general air resistance term. A term F_errordescribing a model error can also be used to estimate theslipstream effect.
    An advantage of the method according to the invention is thatmodels for estimating a driving resistance of a vehicle, usuallybased on a force equation relating the forces acting on the vehicle,are already used in modern vehicles for different purposes. Thesepurposes include, but are not limited to, predicting a behaviour ofthe vehicle as a road gradient changes, estimating a mass of thevehicle, and ensuring an adequate function of cruise controls, gearshifting systems and other systems used in the vehicle. Expandingof such existing models to also include an estimation of theslipstream effect, or the inter-vehicle distance dependent airresistance, can be easily implemented in a vehicle without theneed to install additional sensors, etc.
    The method according to the invention may be initiated as a leadvehicle is detected in front of the motor vehicle. Following thisdetection, steps a-c are conducted. lf the motor vehicle detectsanother lead vehicle, e.g. as a result of an overtaking, the methodshould typically be reinitiated since the slipstream effect causedby the “new” lead vehicle may differ from that caused by theprevious lead vehicle. lf the motor vehicle loses track of the leadvehicle, such as in a curve or when the lead vehicle passes a topof a hill, the method may be reinitiated as the lead vehicle isdetected again, unless it can be established that the detectedvehicle is identical to the previously detected lead vehicle.
    The method according to the invention can be used to give a driverof the vehicle a quick feedback as to how much fuel can be or hasbeen saved by driving close to a lead vehicle. lt can also be usedas a basis for automatically controlling the vehicle to drive at acertain distance to a lead vehicle.
    The distance to the lead vehicle can, according to prior art, bedetermined using e.g. radar technology, camera information, mapdatain combination with GPS (global positioning system)technology, or some other known technique.
    According to one embodiment of the invention, step d comprisescomparing said stored data relating to the estimated drivingresistance to said stored data relating to the detected driving forcefor each of said occasions, and, based on a difference betweenthose, estimating said change in air resistance. By first comparingthe estimated driving resistance and the detected driving force, orthe traction force, of the vehicle on a first occasion, and thereafteron at least a second occasion on which the distance to the leadvehicle has changed, it is possible to deduct a distancedependence of the driving resistance, and thereby estimate theslipstream effect. Thus, very few input parameters are needed toestimate the change in air resistance felt by the vehicle related toa change in distance to the lead vehicle.
    According to one embodiment of the invention, steps a-c arerepeated with a predetermined frequency. The frequency can bevaried depending on the desired accuracy, wherein generally ahigher frequency results in a better accuracy. For example, afrequency of 1 Hz can be used. lf steps a-c are conducted also forother purposes in a motor vehicle, the frequency may be selectedsuch that it is suitable also for those other purposes. For example,a frequency of 100 Hz may be suitable. Such a higher frequencyreduces noise levels. Step d may e.g. be repeated with the samefrequency as steps a-c or with a different frequency, or when apredefined condition is fulfilled.
    According to one embodiment of the invention, steps a-c arerepeated based on a detected distance to the lead vehicle. ln thisembodiment, computing power can be saved by only repeatingsteps a-c when needed for the accuracy of the estimation of theslipstream effect.
    According to one embodiment of the invention, steps a-c arerepeated each time the detected distance to the lead vehicle haschanged by at least a predetermined distance from the previousoccasion, wherein the predetermined distance is within a range of5-50 m. Preferably, the predetermined distance is within a rangeof 10-20 m. A small change in distance between each occasion onwhich steps a-c are repeated results in a high accuracy. Byincreasing the amount that the distance is allowed to changebetween each occasion, computing power may be saved on theexpense of accuracy. Exceeding the upper limit affects theaccuracy of the estimation since the slipstream effect may differsignificantly between each occasion and since the number ofuseful occasions for estimating the slipstream effect will be limited.
    According to one embodiment of the invention, step d is repeatedbased on one of a predetermined frequency and a detecteddistance to the lead vehicle. As described above in connection withsteps a-c, step d may be repeated each time the detected distanceto the lead vehicle has changed by at least a predetermineddistance from the previous occasion, wherein the predetermineddistance is within a range of 5-50 m, preferably 10-20 m. Byrepeating step d based on a detected distance and steps a-c witha predetermined frequency, it is possible to adjust the method tooptimise accuracy and/or resolution. A small change in distancebetween each occasion on which step d is repeated increases theresolution but reduces the accuracy. Step d may also e.g. berepeated more infrequently at large inter-vehicle distances andmore often at small distances, where the slipstream effect isexpected to be more important.
    According to one embodiment of the invention, a model used instep c comprises at least a term F_roll relating to a rollingresistance of the vehicle and a term F_air relating to an airresistance felt by the vehicle. The air resistance and the rollingthe totalresistance of the vehicle and these terms are therefore useful toresistance are important factors affecting drivinginclude in such a model in order to increase the accuracy in thedetermination of the slipstream effect. As already mentioned, theair resistance term F_air may be modelled to include an inter-vehicle distance dependence, or a separate term F_s|ipstreammay be introduced. The model used is preferably based on a forceequation relating the forces acting on the vehicle.
    According to one embodiment of the invention, said model furthercomprises a term F_pt relating to frictional losses in a powertrainof the vehicle. lncluding this term increases the precision in theestimation of the change in air resistance.
    According to one embodiment of the invention, the method furthercomprises determining a mass m of the vehicle, a current roadgradient d, and an acceleration a of the vehicle. These parametersshould all be included when modelling the total driving resistancefelt by the vehicle since they have a large impact on the forcesacting on the vehicle. The mass m can e.g. be determined fromestimation based on the force equation, or from an estimationbased on a suspension of the vehicle. The road gradient can alsobe obtained in many different ways with a large accuracy. Theacceleration a is usually calculated from the velocity of the vehicle,which is given as a signal from e.g. a road speed sensor.
    According to one embodiment of the invention, said mass m, saidroad gradient d, and said acceleration a are used in the estimationof the driving resistance F_res in step c. The total force F_tot =m*a and the gravitational force F_grav affecting the vehicle in thiscase does not need to be modelled, but can be introduced asknown parameters in a model used in said estimation. Thisimproves the accuracy in the later estimation of the change in airresistance.
    According to one embodiment of the invention, step d comprisesdetermining the air resistance felt by the vehicle as a function ofthe distance to the lead vehicle. By determining the air resistancefelt by the vehicle as a function of the inter-vehicle distance, it ispossible to predict changes in air resistance that will occur if thedistance is changed by a certain amount, and thereby also topredict changes in energy consumption of the vehicle. Thus, thismay include interpolating, extrapolating, curve fitting, etc. toobtain a function. The function may be used for giving feedback toa driver or an owner of the vehicle about fuel savings or potentialfuel savings.
    According to one embodiment of the invention, the method furthercomprises utilising said determined change in the air resistancefelt by the vehicle as a function of the distance to the lead vehicleto control a speed of said motor vehicle such that said airresistance is reduced. This is a way of controlling the vehicle suchthat the energy consumption of the vehicle is minimised. Thefunction can be used e.g. as an input parameter to a cruise controlor to another control system of the vehicle.
    According to one embodiment of the invention, the method furthercomprises utilising the determined change in air resistance as aninput parameter in a model used for estimating a driving resistancefelt by the vehicle. ln this way, the model used for estimating thedriving resistance F_res can be continuously improved.
    According to one embodiment of the invention, the method furthercomprises communicating data related to said determined change11in air resistance to a driver of the vehicle. ln this way, the drivercan, if desirable, adapt the driving of the vehicle such that airresistance is minimised. Data can e.g. be communicated visuallyusing a display or similar, or orally using e.g. loudspeakers.
    According to one embodiment of the invention, the method furthercomprises determining a reduction in energy consumptionachieved by driving at a distance to a lead vehicle such that theair resistance felt by the vehicle is reduced. This can be during acertain time interval or during a certain distance interval, such asduring the last 30 minutes or during the last 1 km. The energyconsumption is easier to relate to and more relevant for a driver ora haulage company than the air resistance itself. Data relating tothe reduction in energy consumption can be communicated to adriver as discussed above.
    According to another aspect of the invention, at least the primaryobjective is achieved by a computer program comprising computerprogram code for causing a computer to implement the proposedmethod when the computer program is executed in the computer.
    According to a further aspect of the invention, at least the primaryobjective is achieved by a computer program product comprisinga non-transitory data storage medium which can be read by acomputer and on which the program code of the proposedcomputer program is stored.
    According to a further aspect of the invention, at least the primaryobjective is achieved by an electronic control unit of a motorvehicle comprising an execution means, a memory connected to12the execution means and a data storage medium which isconnected to the execution means and on which the computerprogram code of the proposed computer program is stored.
    According to a further aspect of the invention, at least the primaryobjective is achieved by a motor vehicle comprising the proposedelectronic control unit. The motor vehicle may preferably be a truckor a bus.
    Other advantageous features as well as advantages of the presentinvention will appear from the following description.
    BRIEF DESCRIPTION OF THE DRAWINGSEmbodiments of the invention will in the following be describedwith reference to the appended drawings, in which:Fig. 1 schematically shows a vehicle according to theinvenüon,Fig. 2 is a flow chart showing a method according to theinvenüon,Fig. 3 is a graph schematically showing a slipstream effect,andFig. 4 schematically shows a control unit according to theinvenüon.13DETAILED DESCRIPTION OF EMBODIMENTS OF THEINVENTIONA motor vehicle according to the present invention is shown in fig.1. The motor vehicle 500 may e.g. be a passenger car, a truck ora bus, comprising an engine 501. The engine 501 is comprised ina powertrain 502 which drives driving wheels 503, 504. The motorvehicle 500 further comprises an exhaust treatment system 505and a control unit 510, which is arranged to control the function inthe engine 501.
    Generally, several forces act on the vehicle during operation.Those forces include a driving force F_driving, sometimes alsoreferred to as a traction force, an air resistance force F_air, arolling resistance force F_roll, a gravitational force F_grav, and africtional force F_pt due to friction in the powertrain. The drivingforce F_driving acting on the driving wheels is the torque deliveredby the engine, converted into a force using a present gear ratioand wheel diameter. The air resistance force F_air can beexpressed asF_air = C_air*v2,wherein v is the vehicle velocity and C_air is a constant whichdepends on the air density, the vehicle's area in the direction oftravel, and the vehicle's air resistance coefficient. This in turndepends on the design of the vehicle's surfaces meeting the wind,where in principle all external details on the vehicle have animpact. The air resistance coefficient may therefore be difficult tocalculate, and consequently there is a risk that the air resistance14force is estimated incorrectly. The air resistance force is alsostrongly speed dependent, and consequently an incorrectestimation results in an increased impact with higher vehiclespeeds.
    The rolling resistance F_ro| can be expressed asF_ro| = C_roll*m*g cos d,wherein m is the mass of the vehicle, g is the gravitationalconstant, oi is the road gradient and C_roll is a rolling resistancecoefficient, which primarily depends on the vehicle's tyres/wheels.The rolling resistance coefficient may also be difficult to determineexacfly.The gravitational force F_grav may be expressed asF_grav = m*g sin oi.
    The frictional force F_pt may in some cases be difficult todifferentiate and may be partly or entirely included in the rollingresistance force F_ro| or in the driving force F_driving in a modelof the driving resistance affecting the vehicle.
    A resultant force F_tot represents the force that is converted to anactual acceleration a of the vehicle according to F_tot = m*a.
    A force equation describing the forces acting on a vehicle may beexpressed as follows:F_tot = F_driving - F_air - F_ro| - F_grav - F_pt - F_error,wherein F_driving is the driving force applied by the engine andwherein F_error is a model error accounting for the differencebetween the actual driving force F_driving and the modelleddriving resistance F_res represented byF_res = F_tot + F_air + F_ro| + F_grav + F_pt.ln other words,F_error = F_driving - F_res.ldeally, the model error F_error = O N if the model coincidesperfectly with reality, which is however often not the case.ln the case of a vehicle moving forward at a constant speed on aflat road, F_tot = F_grav = O N. All terms F_air, F_ro| and F_pt willbe negative forces acting to slow the vehicle down, while thedriving force F_driving is positive, acting to keep the speedconstant.
    A method according to an embodiment of the invention is shownin the flow chart in Fig. 2. ln this embodiment, a motor vehicle istravelling forward along a road section as it, in a step SO,encounters and detects another vehicle, a lead vehicle, travellingahead of the vehicle. ln a step S1, a distance to the lead vehicleis detected on a first occasion. This can be done using e.g. radartechnology, camera information, map data in combination withGPS (global positioning system) technology, or the like. Data16relating to the detected distance is stored on a data storagemedium. ln a step S2, which can be performed simultaneously withthe step S1, the driving force F_driving transmitted by the engineis determined, as described above, and data relating thereto arestored. ln a step S3, which can also be performed simultaneouslywith the step S1, the driving resistance felt by the vehicle isestimated using an estimation model, and data relating thereto arestored. The driving resistance may also be, at least in part,determined from measured data relating to e.g. road gradientand/or frictional losses in the power train.
    The motor vehicle now moves closer to the lead vehicle and as thedistance between the vehicles decreases, it is, in a step S4,checked whether steps S1-S3 have been carried out at least twiceand at different detected distances from the lead vehicle. lf not,steps S1-S3 are repeated on at least one more occasion. lf stepsS1-S3 have been carried out at least twice and at differentdetected distances from the lead vehicle, a step S5 is carried out.ln this step, a change in air resistance felt by the vehicle relatedto a change in the distance to the lead vehicle is estimated basedon the stored data relating to the detected distance, the drivingforce, and the driving resistance.
    The estimation of the driving resistance is preferably based on theforce equation discussed above. ln one embodiment, the mass m,the acceleration a and the road gradient oi are determined, whichwill be further discussed below. With those parameters well-known, the total force F_tot and the gravitational force F_grav canbe determined, and a model for estimating the driving resistancein step S3 thus has unknown terms F_air relating to air resistance,17F_ro| relating to rolling resistance, and F_pt relating to frictionallosses in the powertrain. The model also includes an error termF_error, describing a difference between the determined drivingforce F_driving and the modelled driving resistance F_res:F_error = F_driving - F_res.
    Each time step S3 is repeated, a value of F_error is generated andstored. ln step S5, these generated values F_error can be mappedagainst the corresponding detected inter-vehicle distances, suchthat a distance dependence is revealed. Depending on theprecision in the models used to describe the remaining termsF_ro|, F_air, and F_pt, a revealed difference in F_error as theinter-vehicle distance changes can, at least in part, be attributedto the slipstream effect. This is very schematically shown in fig. 3,wherein the error term F_error is plotted as a function of distanceto the lead vehicle. As can be seen, the error term F_errordecreases as the motor vehicle approaches the lead vehicle, whichcan be attributed to the slipstream effect.ln a different embodiment, the slipstream effect is modelled as aseparate term F_slipstream which is included in the model used toestimate the driving resistance. This term will have an oppositesign with respect to the air resistance term F_air, which in thiscase is not modelled as dependent on the inter-vehicle distance,and its absolute value will never be larger than the air resistance.For example, F_slipstream may be estimated as:F_slipstream = F_driving - F_tot - F_grav - F_air - F_ro| - F_pt -F_error.18As described above, the term F_s|ipstream is repeatedly estimatedfor different values of the inter-vehicle distance in order to revea|a distance dependence. For some models, the previouslyestimated F_s|ipstream may be used as an input parameter in thesubsequent estimation on the next occasion in order to improvethe accuracy of the estimation.
    Steps S1-S3 can be repeated at a predetermined frequency or asa certain condition is fulfilled, such as when the distance to thelead vehicle has changed by a predetermined amount, such as bya distance within a range of 5-50 m, preferably 10-20 m. Step S5can be performed each time steps S1-S3 are performed, or onlywhen some predefined condition is fulfilled. This can be e.g. whensteps S1-S3 have been repeated a certain amount of times. StepS5 may include determining the air resistance, or the reduction inair resistance, felt by the vehicle as a function of the distance tothe lead vehicle, i.e. fitting the estimated values to a function. Thefunction may be used to present an achieved or a potentialreduction in air resistance to a driver, e.g. on a display or by audiomeans, such as by means of a loudspeaker.
    The determined change in air resistance as the distance to thelead vehicle changes may also be used to control the speed of thevehicle such that the air resistance is reduced. For example, afunction describing the related change can be used as an inputparameter to a cruise control or to another control system of thevehicle.19The change in air resistance can also be used to determine areduction in energy consumption achieved by driving at a distanceto a lead vehicle such that the air resistance felt by the vehicle isreduced. For example, the reduction energy consumption can bepresented to a driver of the vehicle as a graph showing a reductionin fuel consumption achieved as a function of distance.
    The vehicle mass is typically determined by a mass estimationalgorithm based on either information from a suspension of thevehicle or on a measured or estimated moment of inertia of thevehicle. The acceleration a is typically determined from thevelocity v of the vehicle, given by e.g. a road speed sensor.
    The road gradient d may be obtained in various different ways. ltmay be determined on the basis of map data, e.g. from digital mapswithe.g. GPS (global positioning system)containing topographical information, in combinationpositioning information,information. The positioning information may be used to determinethe location of the vehicle relative to the map data so that the roadgradient can be extracted from the map data. Various present-daycruise control systems use map data and positioning information.Such systems may then provide the map data and positioninginformation required for the method according to the presentinvention, thereby minimising the additional complexity involved indetermining the road gradient.
    The road gradient may be obtained on the basis of a map inconjunction with GPS information, from radar information, fromcamera information, of information from another vehicle, frominformation andpositioning road gradient information storedpreviously on board, or from information obtained from trafficsystems related to the expected travelling route. ln systems wherethere is information exchange between vehicles, road gradientsestimated by one vehicle may also be made available to othervehicles, either directly or via an intermediate unit such as a database or the like.
    One skilled in the art will appreciate that a method for determininga change in air resistance felt by a motor vehicle as its distance toa lead vehicle travelling ahead of the motor vehicle changesaccording to the present invention may be implemented in acomputer program which, when executed in a computer, causesthe computer to conduct the method. The computer programusually takes the form of a computer program product whichcomprises a suitable digital storage medium on which thecomputer program is stored. Said computer-readable digitalstorage medium comprises a suitable memory, e.g. ROM (read-only memory), PROM (programmable read-only memory), EPROM(erasable PROM), flash memory, EEPROM (electrically erasablePROM), a hard disc unit, etc.
    Fig. 4 depicts schematically an electronic control unit 400 of avehicle, corresponding to the electronic control unit 510 of thevehicle 500 shown in fig. 1, provided with an execution means 401which may take the form of substantially any suitable type ofe.g.processing (digital signal processor, DSP), or a circuit with aprocessor or microcomputer, a circuit for digital signalpredetermined specific function (application specific integratedcircuit, ASIC). The execution means 401 is connected to a memoryunit 402 which is situated in the control unit 400. A data storage21medium 403 is also connected to the execution means andprovides the execution means with, for example, the storedprogram code and/or stored data which the execution meansneeds to enable it to do calculations. The execution means is alsoadapted to storing partial or final results of calculations in thememory unit 402.
    The control unit 400 is further provided with respective devices411, 412, 413, 414 for receiving and sending input and outputsignals. These input and output signals may comprise waveforms,pulses or other attributes which the input signal receiving devices411, 413 can detect as information and which can be converted tosignals which the execution means 401 can process. Thesesignals are then supplied to the execution means. The outputsignal sending devices 412, 414 are arranged to convert signalsreceived from the execution means 401, in order to create, e.g. bymodulating them, output signals which can be conveyed to otherparts of the vehicle and/or other systems on board.
    Each of the connections to the respective devices for receivingand sending input and output signals may take the form of one ormore from among a cable, a data bus, e.g. a CAN (controller areanetwork) bus, a MOST (media orientated systems transport) busor some other bus configuration, or a wireless connection. Oneskilled in the art will appreciate that the aforesaid computer maytake the form of the execution means 401 and that the aforesaidmemory may take the form of the memory unit 402.
    Controlcommunicationsystems in modern vehicles generally comprise abus system consisting of one or more22communication buses for connecting together a number ofunits (ECUs),components on board the vehicle.electronic control or controllers, and variousSuch a control system maycomprise a large number of control units and the responsibility fora specific function may be divided between two or more of them.ln the embodiment depicted, the present invention is implementedin the control unit 400 but might also be implemented wholly orpartly in one or more other control units already on board thevehicle or a control unit dedicated to the present invention.Vehicles of the type here concerned are of course often providedwith significantly more control units than shown here, as oneskilled in the art will surely appreciate.
    The invention is of course not in any way restricted to theembodiments described above. On the contrary, many possibilitiesto modifications thereof will be apparent to a person with ordinaryskill in the art without departing from the basic idea of the inventionsuch as defined in the appended claims.
    权利要求:
    Claims (15)
    [1] 1. A method for determining a change in air resistance felt by amotor vehicle (500) as its distance to a detected lead vehicletravelling ahead of the motor vehicle (500) changes, wherein saidmotor vehicle comprises an engine (501) for transmission of adriving force to at least one driving wheel (503, 504),characterised inthat it comprises the steps:a) detecting a distance to said lead vehicle and storing datarelating thereto,b) determining the driving force F_driving transmitted by theengine (501) and storing data relating thereto,c) estimating a driving resistance F_res felt by the vehicle (500)and storing data relating thereto,wherein steps a-c are carried out at least on a first occasion andon a second occasion, between which occasions the distance tothe detected lead vehicle has changed, and wherein the methodfurther comprises the step:d) based on said stored data relating to the detected distance,the driving force F_driving, and the driving resistance F_res,estimating a change in air resistance felt by the vehicle (500) related to a change in the distance to the lead vehicle.
    [2] 2. The method according to claim 1, wherein step d comprisescomparing said stored data relating to the estimated drivingresistance F_res to said stored data relating to the detecteddriving force F_driving for each of said occasions, and, based on|n a|r a difference between those, estimating said change resistance. 24
    [3] 3. The method according to claim 1 or 2, wherein steps a-c are repeated with a predetermined frequency.
    [4] 4. The method according to claim 1 or 2, wherein steps a-c arerepeated based on a detected distance to the lead vehicle,preferably each time the detected distance to the lead vehicle haschanged by at least a predetermined distance from the previous occasion.
    [5] 5. The method according to any one of the preceding claims,wherein step d is repeated based on one of a predetermined frequency and a detected distance to the lead vehicle.
    [6] 6. The method according to any one of the preceding claims,wherein a model used in step c comprises at least a term F_rollrelating to a rolling resistance of the vehicle (500) and a term F_airrelating to an air resistance felt by the vehicle (500), andpreferably wherein said model further comprises a term F_ptrelating to frictional losses in a powertrain (502) of the vehicle (500).
    [7] 7. The method according to any one of the preceding claims,further comprising determining a mass m of the vehicle (500), acurrent road gradient d, and an acceleration a of the vehicle (500),preferably wherein said mass m, said road gradient d, and saidacceleration a are used in the estimation of the driving resistance F_driving in step c.
    [8] 8. The method according to any one of the preceding claims,wherein step d comprises determining the air resistance felt by thevehicle (500) as a function of the distance to the lead vehicle,preferably wherein the method further comprises utilising saiddetermined change in the air resistance felt by the vehicle (500)as a function of the distance to the lead vehicle to control a speed of said motor vehicle (500) such that said air resistance is reduced.
    [9] 9. The method according to any one of the preceding claims,further comprising utilising the determined change in air resistanceas an input parameter in a model used for estimating a driving resistance felt by the vehicle (500).
    [10] 10. The method according to any one of the preceding claims,further comprising communicating data related to said determined change in air resistance to a driver of the vehicle (500).
    [11] 11. The method according to any one of the preceding claims,further comprising determining a reduction in energy consumptionachieved by driving at a distance to a lead vehicle such that the air resistance felt by the vehicle (500) is reduced.
    [12] 12. A computer program comprising computer program code forcausing a computer to implement a method according to any oneof the claims 1-11 when the computer program is executed in the computer.
    [13] 13. A computer program product comprising a non-transitory data storage medium which can be read by a computer and on 26 which the program code of a computer program according to claim 12 is stored.
    [14] 14. An electronic control unit (400, 510) of a motor vehicle (500)comprising an execution means (401), a memory (402) connectedto the execution means and a data storage medium (403) which isconnected to the execution means and on which the computerprogram code of a computer program according to claim 12 is stored.
    [15] 15. A motor vehicle (500) comprising an electronic control unit(400, 510) according to claim14.
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    同族专利:
    公开号 | 公开日
    DE102016012465A1|2017-05-04|
    DE102016012465B4|2021-10-21|
    BR102016023026A2|2017-05-02|
    SE540963C2|2019-01-29|
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    KR101316217B1|2011-09-28|2013-10-08|현대자동차주식회사|Method and system for measured aerodynamic force information to improve mileage and driving stability for vehicle|
    SE537447C2|2012-03-27|2015-05-05|Scania Cv Ab|Device and method for streamlining fuel utilization during the speed of a vehicle|CN107139929B|2017-05-15|2019-04-02|北理慧动（常熟）车辆科技有限公司|A kind of estimation of heavy type fluid drive vehicle broad sense resistance coefficient and modification method|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1551395A|SE540963C2|2015-10-29|2015-10-29|A method for determining a change in air resistance felt by a motor vehicle|SE1551395A| SE540963C2|2015-10-29|2015-10-29|A method for determining a change in air resistance felt by a motor vehicle|
    BR102016023026A| BR102016023026A2|2015-10-29|2016-10-03|method for determining a change in air resistance perceived by a motor vehicle|
    DE102016012465.2A| DE102016012465B4|2015-10-29|2016-10-19|Method for determining a change in air resistance acting on a motor vehicle|
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