SE1551564A1 - Method and system for facilitating steering of a vehicle during driving along a road - Google Patents
Method and system for facilitating steering of a vehicle during driving along a road Download PDFInfo
- Publication number
- SE1551564A1 SE1551564A1 SE1551564A SE1551564A SE1551564A1 SE 1551564 A1 SE1551564 A1 SE 1551564A1 SE 1551564 A SE1551564 A SE 1551564A SE 1551564 A SE1551564 A SE 1551564A SE 1551564 A1 SE1551564 A1 SE 1551564A1
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- Prior art keywords
- yaw rate
- vehicle
- torque
- influence
- steering
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D15/00—Steering not otherwise provided for
- B62D15/02—Steering position indicators ; Steering position determination; Steering aids
- B62D15/025—Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
- B62D6/001—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits the torque NOT being among the input parameters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
- B62D6/002—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels
- B62D6/003—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels in order to control vehicle yaw movement, i.e. around a vertical axis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
- B62D6/04—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
Abstract
ABSTRACT The present invention relates to a method for facilitating steering of a vehicleduring driving along a road. The method comprises the steps of: detectingthe yaw rate of the vehicle; modelling (230, G(z)) the yaw rate of the vehiclebased upon the steering torque of the vehicle; comparing (240) the detectedand modelled yaw rate. The method further comprises the steps of:determining the influence of external forces on the yaw rate based on saidcomparison of detected and modelled yaw rate; based upon the determined(270) acompensation torque for compensating the steering torque of the vehicle; influence of external forces on the yaw rate determiningand compensating the steering torque based upon said determined compensation torque. The present invention also relates to a system for facilitating steering of avehicle during driving along a road. The present invention also relates to avehicle. The present invention also relates to a computer program and acomputer program product. (Fig. 4)
Description
METHOD AND SYSTEM FOR FACILITATING STEERING OF A VEHICLEDURING DRIVING ALONG A ROAD TECHNICAL FIELD The invention relates to a method for facilitating steering of a vehicle duringdriving along a road according to the preamble of claim 1. The invention alsorelates to a system for facilitating steering of a vehicle during driving along aroad. The invention also relates to a vehicle. The invention in addition relatesto a computer program and a computer program product.
BACKGROUND ART With automated driving using torque control, for example a lane keep assistfunction, external effects such asconfiguration of the road, and/or lateral wind may cause the lane keeping road banking, i.e. cross slopedfunction to result in repeated bouncing against the boundary of the lanewithin which the vehicle is intended to be kept, and thus create behaviour ofthe vehicle which is uncomfortable for vehicle occupants. The external effectswill then push the vehicle against one side of the lane. Also when drivingmanually, the driver needs to keep a constant torque at the steering wheel tocompensate for these effects, which can be tiresome.
US5694319, DE3625392 and FR2915447 disclose applications where thedifference between a measured value of the yaw rate and a set point aredetermined, the set point being determined by means of a mathematicalmodel based upon the angle of the steering wheel. The thus determineddifference is used for influencing automatic steering of a vehicle.
There is however a need for simplifying the way of providing a basis forinfluencing steering of a vehicle during driving along a road.
OBJECTS OF THE INVENTION An object of the present invention is to provide a method for facilitatingsteering of a vehicle during driving along a road which provides an easy andefficient way of compensating the steering of the vehicle due to externalforces.
Another object of the present invention is to provide a system for facilitatingsteering of a vehicle during driving along a road which provides an easy andefficient way of compensating the steering of the vehicle due to externalforces.
SUMMARY OF THE INVENTION These and other objects, apparent from the following description, areachieved by a method, a system, a vehicle, a computer program and acomputer program product, as set out in the appended independent claims.Preferred embodiments of the method and the system are defined inappended dependent claims.
Specifically an object of the invention is achieved by a method for facilitatingsteering of a vehicle during driving along a road. The method comprises thesteps of: detecting the yaw rate of the vehicle; modelling the yaw rate of thevehicle; comparing the detected and modelled yaw rate. The modelled yawrate is based upon the steering torque of the vehicle. The method furthercomprising the steps of: determining the influence of external forces on theyaw rate based on said comparison of detected and modelled yaw rate;based upon the determined influence of external forces on the yaw ratedetermining a compensation torque for compensating the steering torque ofthe vehicle; and compensating the steering torque based upon saiddetermined compensation torque.
Hereby an easy and efficient method for compensating the steering of thevehicle due to external forces is facilitated, by thus basing the modelled yawrate upon the steering torque of the vehicle compensation of the steering ofthe vehicle without the need of information regarding the steering angle of thesteering wheel of the vehicle. For automated steering functions such as lanekeep assist, compensation of external forces will prevent the vehicle frombouncing against the boundary of the lane within which the vehicle isintended to be kept. For manual driving, the driver will have a muchincreased comfort and does not have to compensate for external effects suchas longer periods of road banking, i.e. cross sloped configuration of the road,and/or side wind.
According to an embodiment of the method the result of said comparisonbetween the detected and modelled yaw rate is filtered so as to avoidinfluence of rapid changes. Hereby a more efficient compensation isobtained, further improving the comfort during driving along a road in thatrapid changes are avoided.
According to an embodiment of the method the modelled yaw rate isobtained via a transfer function. By applying a transfer function an efficientway of obtaining the modelled yaw rate is facilitated. The transfer function isconfigured to transfer the steering torque to the modelled yaw rate. Thetransfer function comprises calculating what the yaw rate would be after acertain time based upon a certain steering torque, i.e. a certain torqueapplied on the steering wheel of the vehicle. The method thus comprises thestep of obtaining the modelled yaw rate from the steering torque by means ofa transfer function.
According to an embodiment of the method a static gain for obtaining saidcompensation torque is obtained via said transfer function. The static gainprovides information regarding the torque that needs to be maintained inorder to maintain a constant yaw rate.
According to an embodiment of the method said external forces emanatefrom one or more of: influence of cross sloped configuration of the road;influence of lateral wind; and influence of flat tire.
A system for facilitating steering of a vehicle during driving along a roadcomprising means for detecting the yaw rate of the vehicle. The systemcomprises modelling means for modelling the yaw rate of the vehicle; andmeans for comparing the detected and modelled yaw rate. The modellingmeans is arranged to model the yaw rate based upon the steering torque ofthe vehicle. The system further comprises means for determining theinfluence of external forces on the yaw rate based on said comparison ofdetected and modelled yaw rate; means for determining a compensationtorque for compensating the steering torque of the vehicle based upon thedetermined influence of external forces on the yaw rate; and means forcompensating the steering torque based upon said determined compensationtorque.
According to an embodiment the system comprises filtering means forfiltering the result of said comparison between the detected and modelledyaw rate so as to avoid influence of rapid changes.
According to an embodiment of the system the modelling means is arrangedto obtain the modelled yaw rate via a transfer function.
According to an embodiment of the system a static gain for obtaining saidcompensation torque is arranged to be obtained via said transfer function.
According to an embodiment of the system said external forces emanatefrom one or more of: influence of cross sloped configuration of the road;influence of lateral wind; and influence of flat tire.
The system for facilitating steering of a vehicle during driving along a road isadapted to perform the methods as set out herein.
The system according to the invention has the advantages according to thecorresponding method claims.
Specifically an object of the invention is achieved by a vehicle comprising asystem according to the invention as set out herein.
Specifically an object of the invention is achieved by a computer program forfacilitating steering of a vehicle during driving along a road, said computerprogram comprising program code which, when run on an electronic controlunit or another computer connected to the electronic control unit, causes theelectronic control unit to perform methods as set out herein.
Specifically an object of the invention is achieved by a computer programproduct comprising a digital storage medium storing the computer program.
BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention reference is made to the following detailed description when read in conjunction with theaccompanying drawings, wherein like reference characters refer to like parts throughout the several views, and in which: Fig. 1 schematically illustrates a side view of a vehicle according to thepresent invention; Fig. 2 schematically illustrates a rear view of the vehicle in fig. 1 beingsubjected to external forces comprising on cross sloped configuration of theroad and influence of lateral wind; Fig. 3 schematically illustrates a steering configuration of a vehicle andrelated torques according to an embodiment of the invention; Fig. 4 schematically illustrates a block diagram of a system for facilitatingsteering of a vehicle during driving along a road according to an embodimentof the present invention; Fig. 5 schematically illustrates a block diagram of a system for providing acompensation torque for facilitating steering of a vehicle during driving alonga road according to an embodiment of the present invention; Fig. 6 schematically illustrates a block diagram of a method for facilitatingsteering of a vehicle during driving along a road according to an embodimentof the present invention; and Fig. 7 schematically illustrates a computer according to an embodiment of the present invention.
DETAILED DESCRIPTION Hereinafter the term “link” refers to a communication link which may be aphysical connector, such as an optoelectronic communication wire, or a non-physical connector such as a wireless connection, for example a radio or microwave link.
Hereinafter the term “steering torque" refers to the total input torque acting onthe steering column of the vehicle.
The “steering torque”, i.e. the total input torque acting on the steering column,comprises a driver torque and according to an embodiment, a possibleassistance torque being a boost of the driver torque. The steering torquefurther comprises an external torque being a demanded torque for steeringthe vehicle. Fig. 3 illustrates an example of a steering configuration and howthe steering torque relates to driver torque and external torque.
Fig. 1 schematically illustrates a side view of a vehicle 1 according to thepresent invention. The exemplified vehicle 1 is a heavy vehicle in the shapeof a truck. The vehicle according to the present invention could be anysuitable vehicle such as a bus or a car. The vehicle comprises a system I forfacilitating steering of a vehicle during driving along a road R.
Fig. 2 schematically illustrates a rear view of the vehicle 1 in fig. 1 beingsubjected to external forces. The vehicle has wheels of which left and rightrear wheels LR, RR are shown. The external forces comprise cross slopedconfiguration of the road R on which the vehicle 1 is travelling. The crosssloped configuration of the road R is called road banking, the road R having acertain inclination d such that water is allowed to run off the road. Theexternal forces comprise influence of lateral wind A. The external forces mayalso comprise a flat tire on a wheel of the vehicle.
With automated driving using torque control, for example a lane keep assistfunction, such external effects may cause the lane keeping function to resultin repeated bouncing against the boundary of the lane within which thevehicle is intended to be kept, and thus create behaviour of the vehicle whichis uncomfortable for vehicle occupants. The external effects will then pushthe vehicle against one side of the lane. Also when driving manually, thedriver needs to keep a constant torque at the steering wheel to compensatefor these effects, which can be tiresome.
The present invention provides method and system for facilitating steering ofa vehicle during driving along a road so as to compensate for such externalforces. This is achieved by detecting the yaw rate of the vehicle andmodelling the yaw rate of the vehicle and comparing the detected andmodelled yaw rate. The modelled yaw rate is based upon the steering torqueof the vehicle. The influence of external forces on the yaw rate is determinedbased on the comparison of detected and modelled yaw rate. Acompensation torque for compensating the steering torque of the vehicle is then determined based upon the determined influence of external forces on the yaw rate. The steering torque is compensated based upon the determined compensation torque.The present invention is described in more detail with reference to fig. 4-7.
Fig. 3 schematically illustrates a steering configuration of a vehicle andrelated torques according to an embodiment of the invention.
The vehicle comprises a steering wheel SW. The steering wheel SW isconnected to the front wheels LF, RF via a steering column SC connected toa link arrangement LA for turning the wheels LF, RF.
The driver torque DT is provided by applying torque to the steering wheelSW. The driver torque DT is determined by means of a torque sensor TS.The driver torque DT is boosted by means of a gain G so as to obtain anassistance torque AT which represents a boost of the driver torque in order toobtain a good feeling for the driver by steering the vehicle. The assistancetorque AT may vary with vehicle speed. The assistance torque AT is provideda specific feeling during steering of the vehicle such that by low speeds ahigh boost is provided to facilitate drive at low speeds and at high speed alow gain is provided in order to stiffen the steering wheel SW.
An external torque ET may according to an embodiment be provided which isadded to the assistance torque AT. The external torque ET would accordingto a variant have the effect that if the driver lets go of the steering wheel SWit is only the external toque ET that provides the steering. During drive incurve the external torque ET may be added in order to follow the curvature.The external torque may correspond to a compensation torque determined inaccordance with the present invention. The external torque ET may alsocomprise a torque based on a lane keep assistance function. lf a certain external torque ET is demanded, e.g. 5 Nm to the right, i.e.external torque = - 5 Nm, and the driver keeps the steering wheel totally still, and the boost correspond to a certain gain, e.g. 2, the driver will feel a torqueof 5/2=2,5 Nm in the steering wheel SW.
The steering torque ST is the total input torque to the steering column SC.The steering torque ST is boosted by means of the link arrangement LAconnected to the steering column SC. The steering torque ST is the drivertorque DT + the assistance torque AT and where applicable also + theexternal torque ET. The steering torque ST is thus determined by means ofthe torque sensor TS and the gain G and by adding the possible externaltorque ET. The external torque ET is a demanded torque and thus knownand provided from an electronic control unit.
Fig. 4 schematically illustrates a system I for facilitating steering of a vehicleduring driving along a road according to an embodiment of the present invention.The system I comprises an electronic control unit 100.
The system I comprises means 110 for determining the steering torque. Themeans 110 for determining the steering torque may comprise any suitabletorque sensor for determining the steering torque. The means 110 fordetermining the steering torque may comprise the electronic control unit. Themeans 110 for determining the steering torque may be arranged to determinethe steering torque in accordance with the determination of the steeringtorque as described with reference to fig. 3.
The system I comprises means 120 for detecting the yaw rate of the vehicle.The means 120 for detecting the yaw rate comprises any suitable detectorunit for detecting the yaw rate. The detector unit is configured todetect/measure the rotation in the x/y-plane. The detector unit is according toan embodiment a gyro configured to sense the rotation in the x/y-plane. Thedetection by means of said detector unit is according to an embodiment performed continuously.
The system I comprises modelling means 130 for modelling the yaw rate ofthe vehicle. The modelling means 130 is arranged to model the yaw ratebased upon the steering torque of the vehicle. The modelling means 130 isarranged to provide a model wherein a certain torque gives a certain yawangle and how quickly it affects yaw rate. The modelling means 130 isaccording to an embodiment a dynamic model built up by means of meaSUFemeFltS.
The modelling means 130 is arranged to obtain the modelled yaw rate via atransfer function. The transfer function is comprised in the modelling means130 and is configured to transfer the steering torque to a yaw rate. Thetransfer function is configured to calculate which yaw rate it would be within acertain time based on a certain steering torque as input.
The transfer function of the modelling means 130 is configured to provide arelationship between steering torque and yaw rate. The transfer function ofthe modelling means 130 is configured to provide a static gain relating to thetorque required for obtaining a constant yaw rate. The transfer function of themodelling means 130 is configured to provide a moment of inertia relating tothe rate of change of the yaw rate due to turning of the steering wheel of thevehicle.
The system I comprises means 140 for comparing the detected and modelledyaw rate. The means 140 for comparing the detected and modelled yaw ratecomprises calculation means for calculating the difference between thedetected and modelled yaw rate. The means 140 is according to anembodiment comprised in the electronic control unit 100.
The system I comprises filtering means 150 for filtering the result of saidcomparison between the detected and modelled yaw rate so as to avoidinfluence of rapid changes. The comparison is thus performed during acertain time span and by filtering the result such rapid changes can beavoided. 11 The system I comprises means 160 for determining the influence of externalforces on the yaw rate based on said comparison of detected and modelledyaw rate. lf there is a difference in the comparison of detected and modelledyaw rate the difference is assumed to relate to external forces.
According to an embodiment of the system said external forces emanatefrom one or more of: influence of cross sloped configuration of the road;influence of lateral wind; and influence of flat tire. lf there is no difference in the comparison of detected and modelled yaw ratethere is likely no influence of external forces. This would be the case if theroad is essentially horizontal and there are no lateral wind affecting thevehicle.
The system I comprises means 170 for determining a compensation torquefor compensating the steering torque of the vehicle based upon thedetermined influence of external forces on the yaw rate.
According to an embodiment of the system a static gain for obtaining saidcompensation torque is arranged to be obtained via said transfer function ofthe modelling means 130. The static gain is the gain provided by the systemwhen the time goes to infinity. The static gain is used for determining therequired steering torque in order to compensate for the error correspondingto the difference between the detected and modelled yaw rate.
The system I comprises means 180 for compensating the steering torquebased upon said determined compensation torque. The means 180 forcompensating the steering torque based upon said determined compensationtorque is arranged to be added/subtracted so as to compensate for thetorque provided by the external forces such that only the vehicle relatedtorque/driver torque affects the driving of the vehicle such that the vehicle isnot affected by the external forces. Thus, the experience for the driver will bethe same as if there were no external forces, e.g. no lateral wind and nobanked road. 12 According to an embodiment external forces could also be detected.
According to an embodiment the external force relating to cross slopedconfiguration of the road, i.e. road banking is detected by means of detectingthe Iateral acceleration. The yaw rate due to cross sloped configuration of theroad can thus be determined by calculation by dividing the thus detectedIateral acceleration with the vehicle speed and subtracting the measured yawrate.
The external force relating to Iateral wind could also be detected by means of one or more detector units.
The electronic control unit 100 is operably connected to the means 110 fordetermining the steering torque via a link 10. The electronic control unit 100is via the link 10 arranged to receive a signal from said means 110representing data for steering toque.
The electronic control unit 100 is operably connected to the means 120 fordetecting the yaw rate of the vehicle via a link 20. The electronic control unit100 is via the link 20 arranged to receive a signal from said means 120representing data for the detected yaw rate of the vehicle.
The electronic control unit 100 is operably connected to the modelling means130 for modelling the yaw rate of the vehicle via a link 30a. The electroniccontrol unit 100 is via the link 30a arranged to send a signal to said means130 representing data for the steering toque.
The electronic control unit 100 is operably connected to the modelling means130 for modelling the yaw rate of the vehicle based on the steering torque viaa link 30b. The electronic control unit 100 is via the link 30b arranged toreceive a signal from said means 130 representing data for the modelled yawrate.
The electronic control unit 100 is operably connected to the modelling means130 for modelling the yaw rate of the vehicle based on the steering torque via 13 a link 30c. The electronic control unit 100 is via the link 30c arranged toreceive a signal from said means 130 representing data for static gain.
The electronic control unit 100 is operably connected to the means 140 forcomparing the detected and modelled yaw rate via a link 40a. The electroniccontrol unit 100 is via the link 40a arranged to send a signal to said means140 representing data for detected yaw rate.
The electronic control unit 100 is operably connected to the means 140 forcomparing the detected and modelled yaw rate via a link 40b. The electroniccontrol unit 100 is via the link 40b arranged to send a signal to said means140 representing data for modelled yaw rate.
The electronic control unit 100 is operably connected to the means 140 forcomparing the detected and modelled yaw rate via a link 40c. The electroniccontrol unit 100 is via the link 40c arranged to receive a signal from saidmeans 140 representing data for result of comparison between detected andmodelled yaw rate, i.e. data for difference between detected and modelled yaw rate.
The electronic control unit 100 is operably connected to the filtering means150 for filtering the result of said comparison between the detected andmodelled yaw rate so as to avoid influence of rapid changes via a link 50a.The electronic control unit 100 is via the link 50a arranged to send a signal tosaid means 150 representing data for result of comparison between detectedand modelled yaw rate.
The electronic control unit 100 is operably connected to the filtering means150 for filtering the result of said comparison between the detected andmodelled yaw rate so as to avoid influence of rapid changes via a link 50b.The electronic control unit 100 is via the link 50b arranged to receive a signalfrom said means 150 representing data for filtered result of comparisonbetween detected and modelled yaw rate. 14 The electronic control unit 100 is operably connected to the means 160 fordetermining the influence of external forces on the yaw rate based on saidcomparison of detected and modelled yaw rate via a link 60a. The electroniccontrol unit 100 is via the link 60a arranged to send a signal to said means160 representing data for filtered result of comparison between detected andmodelled yaw rate.
The electronic control unit 100 is operably connected to the means 160 fordetermining the influence of external forces on the yaw rate based on saidcomparison of detected and modelled yaw rate via a link 60b. The electroniccontrol unit 100 is via the link 60b arranged to receive a signal from saidmeans 160 representing data for influence of external forces on the yaw rate.
The electronic control unit 100 is operably connected to the means 170 fordetermining a compensation torque for compensating the steering torque ofthe vehicle based upon the determined influence of external forces on theyaw rate via a link 70a. The electronic control unit 100 is via the link 70aarranged to send a signal to said means 170 representing data for influenceof external forces on the yaw rate.
The electronic control unit 100 is operably connected to the means 170 fordetermining a compensation torque for compensating the steering torque ofthe vehicle based upon the determined influence of external forces on theyaw rate via a link 70b. The electronic control unit 100 is via the link 70barranged to send a signal to said means 170 representing data for static gainfrom the transfer function.
The electronic control unit 100 is operably connected to the means 170 fordetermining a compensation torque for compensating the steering torque ofthe vehicle based upon the determined influence of external forces on theyaw rate via a link 70c. The electronic control unit 100 is via the link 70carranged to receive a signal from said means 170 representing data forcompensation torque for compensating the steering torque of the vehicle.
The electronic control unit 100 is operably connected to the means 180 forcompensating the steering torque based upon said determined compensationtorque via a link 80a. The electronic control unit 100 is via the link 80aarranged to send a signal to said means 180 representing data forcompensation torque for compensating the steering torque of the vehicle.
The electronic control unit 100 is operably connected to the means 180 forcompensating the steering torque based upon said determined compensationtorque via a link 80b. The electronic control unit 100 is via the link 80barranged to receive a signal from said means 180 representing data forcompensating the steering torque.
Fig. 5 schematically illustrates a block diagram of a system ll for providing acompensation torque for facilitating steering of a vehicle during driving alonga road according to an embodiment of the present invention.
The system ll could be a subsystem to the system l. The system ll maycomprise parts of the system l. The system ll is arranged to provide generallythe same information as the system l.
The system ll comprises a transfer function G(z) configured to provide arelationship between steering torque and yaw rate. The transfer function G(z)is part of a modelling means 230. The transfer function G(z) is thuscomprised in the modelling means 230 and is configured to transfer thesteering torque to a yaw rate.
The modelling means 230 is arranged for modelling the yaw rate of thevehicle. The modelling means 230 is arranged to model the yaw rate basedupon the steering torque of the vehicle. The modelling means 230 isarranged to receive a signal via a link 230a representing data for steeringtorque.
The modelling means 230 is arranged to provide a model wherein a certaintorque gives a certain yaw angle and how quickly it affects yaw rate. The 16 modelling means 230 is according to an embodiment a dynamic model built up by means of measurements.
The transfer function G(z) is configured to calculate which yaw rate it wouldbe within a certain time based on a certain steering torque as input via thelink 230a.
The transfer function G(z) of the modelling means 230 is configured toprovide a static gain relating to the torque required for obtaining a constantyaw rate. The transfer function G(z) of the modelling means 230 is configuredto provide a moment of inertia relating to the rate of change of the yaw ratedue to turning of the steering wheel of the vehicle.
The system ll comprises means 240 for comparing detected and modelledyaw rate.
The means 240 for comparing the detected and modelled yaw rate isarranged to receive a signal via a link 220a representing detected yaw rate.
The means 240 for comparing the detected and modelled yaw rate isarranged to receive a signal via a link 230b representing the modelled yawrate.
The means 240 for comparing the detected and modelled yaw ratecomprises calculation means for calculating the difference between thedetected and modelled yaw rate.
The system ll comprises filtering means 250 for filtering the result of saidcomparison between the detected and modelled yaw rate so as to avoidinfluence of rapid changes.
The filtering means 250 is arranged to receive a signal via a link 240crepresenting data for result of comparison between the detected andmodelled yaw rate. 17 The comparison is thus performed during a certain time span and by filteringthe result such rapid changes can be avoided.
The influence of external forces on the yaw rate is determined based on saidcomparison of detected and modelled yaw rate. lf there is a difference in thecomparison of detected and modelled yaw rate the difference is assumed torelate to external forces. The external forces emanate from one or more of:influence of cross sloped configuration of the road; influence of lateral wind;and influence of flat tire.
The system ll comprises means 270 for determining a compensation torquefor compensating the steering torque of the vehicle based upon thedetermined influence of external forces on the yaw rate.
The means 270 for determining a compensation torque is operablyconnected to the modelling means 230 and hence the transfer function G(z)via a link 230c. The means 270 for determining a compensation torque isarranged to receive a signal via the link 230c representing data for staticgain. The static gain is the gain provided by the system when the time goesto infinity. The static gain is used for determining the required torque in orderto compensate for the error.
A static gain for obtaining said compensation torque is thus arranged to beobtained via said transfer function G(z) of the modelling means 230.
The means 270 for determining a compensation torque is operablyconnected to the filtering means 250 via a link 250b. The means 270 fordetermining a compensation torque is arranged to receive a signal via thelink 250b representing data for filtered result of comparison between thedetected and modelled yaw rate.
The means 270 for determining a compensation torque is arranged toprocess the data for static gain and the data for result of comparison betweenthe detected and modelled yaw rate so as to obtain the compensation torque. 18 The thus obtained compensation torque may via a link 270b be sent to ameans for compensating the steering torque. Compensation of the steeringtorque is thus based upon the determined compensation torque. Thedetermined compensation torque may be added/subtracted to the steeringtorque so as to compensate for the torque provided by the external forces.The determined compensation torque may be comprised or constitute theexternal torque ET according to fig. 3.
Fig. 6 schematically illustrates a block diagram of a method for facilitatingsteering of a vehicle during driving along a road according to an embodiment of the present invention.
According to the embodiment the method for facilitating steering of a vehicleduring driving along a road comprises a step S1. ln this step the yaw rate ofthe vehicle is detected.
According to the embodiment the method for facilitating steering of a vehicleduring driving along a road comprises a step S2. ln this step the yaw rate ofthe vehicle is modelled, the modelled yaw being is based upon the steeringtorque of the vehicle.
According to the embodiment method for facilitating steering of a vehicleduring driving along a road comprises a step S3. ln this step the detectedand modelled yaw rate are compared.
According to the embodiment the method for facilitating steering of a vehicleduring driving along a road comprises a step S4. ln this step the influence ofexternal forces on the yaw rate based on said comparison of detected andmodelled yaw rate is determined.
According to the embodiment the method for facilitating steering of a vehicleduring driving along a road comprises a step S5. ln this step a compensationtorque for compensating the steering torque of the vehicle based upon the determined influence of external forces on the yaw rate is determined. 19 According to the embodiment the method for facilitating steering of a vehicleduring driving along a road comprises a step S6. ln this step the steeringtorque is compensated based upon said determined compensation torque.
Hereby an easy and efficient method for compensating the steering of thevehicle due to external forces is facilitated, by thus basing the modelled yawrate upon the steering torque of the vehicle compensation of the steering ofthe vehicle without the need of information regarding the steering angle of thesteering wheel of the vehicle. For automated steering functions such as lanekeep assist, compensation of external forces will prevent the vehicle frombouncing against the boundary of the lane within which the vehicle isintended to be kept. For manual driving, the driver will have a muchincreased comfort and does not have to compensate for external effects suchas longer periods of road banking, i.e. cross sloped configuration of the road,and/or side wind.
According to an embodiment of the method the result of said comparisonbetween the detected and modelled yaw rate is filtered so as to avoidinfluence of rapid changes. Hereby a more efficient compensation isobtained, further improving the comfort during driving along a road in thatrapid changes are avoided.
According to an embodiment of the method the modelled yaw rate isobtained via a transfer function. By applying a transfer function an efficientway of obtaining the modelled yaw rate is facilitated. The transfer function isconfigured to transfer the steering torque to the modelled yaw rate. Thetransfer function comprises calculating what the yaw rate would be after acertain time based upon a certain steering torque, i.e. a certain torqueapplied on the steering wheel of the vehicle. The method thus comprises thestep of obtaining the modelled yaw rate from the steering torque by means ofa transfer function.
According to an embodiment of the method a static gain for obtaining saidcompensation torque is obtained via said transfer function. The static gainprovides information regarding the torque that needs to be maintained inorder to maintain a constant yaw rate.
According to an embodiment of the method said external forces emanatefrom one or more of: influence of cross sloped configuration of the road;influence of Iateral wind; and influence of flat tire.
With reference to figure 7, a diagram of an apparatus 500 is shown. Thecontrol unit 100 described with reference to fig. 4 may according to anembodiment comprise apparatus 500. Apparatus 500 comprises a non-volatile memory 520, a data processing device 510 and a read/write memory550. Non-volatile memory 520 has a first memory portion 530 wherein acomputer program, such as an operating system, is stored for controlling thefunction of apparatus 500. Further, apparatus 500 comprises a bus controller,a serial communication port, I/O-means, an A/D-converter, a time date entryand transmission unit, an event counter and an interrupt controller (notshown). Non-volatile memory 520 also has a second memory portion 540.
A computer program P is provided comprising routines for facilitating steeringof a vehicle during driving along a road according to an embodiment of thepresent invention. The program P comprises routines for detecting the yawrate of the vehicle. The program P comprises routines for modelling the yawrate of the vehicle, the modelled yaw rate being based upon the steeringtorque of the vehicle. The modelled yaw rate is according to a variantobtained via a transfer function. The program P comprises routines forcomparing the detected and modelled yaw rate. The program P comprisesroutines for filtering the result of said comparison between the detected andmodelled yaw rate so as to avoid influence of rapid changes. The program Pcomprises routines for determining the influence of external forces on theyaw rate based on said comparison of detected and modelled yaw rate. The program P comprises routines for determining a compensation torque for 21 compensating the steering torque of the vehicle based upon the determinedinfluence of external forces on the yaw rate. The external forces emanatefrom one or more of: influence of cross sloped configuration of the road;influence of lateral wind; and influence of flat tire. A static gain for obtainingsaid compensation torque is obtained via said transfer function. The programP comprises routines for compensating the steering torque based upon saiddetermined compensation torque. The computer program P may be stored inan executable manner or in a compressed condition in a separate memory560 and/or in read/write memory 550.
When it is stated that data processing device 510 performs a certain functionit should be understood that data processing device 510 performs a certainpart of the program which is stored in separate memory 560, or a certain partof the program which is stored in read/write memory 550.
Data processing device 510 may communicate with a data communicationsport 599 by means of a data bus 515. Non-volatile memory 520 is adaptedfor communication with data processing device 510 via a data bus 512.Separate memory 560 is adapted for communication with data processingdevice 510 via a data bus 511. Read/write memory 550 is adapted forcommunication with data processing device 510 via a data bus 514. To thedata communications port 599 e.g. the links connected to the control units100 may be connected.
When data is received on data port 599 it is temporarily stored in secondmemory portion 540. When the received input data has been temporarilystored, data processing device 510 is set up to perform execution of code ina manner described above. The signals received on data port 599 can beused by apparatus 500 for detecting the yaw rate of the vehicle. The signalsreceived on data port 599 can be used by apparatus 500 for modelling theyaw rate of the vehicle, the modelled yaw rate being based upon the steeringtorque of the vehicle. The modelled yaw rate is according to a variantobtained via a transfer function. The signals received on data port 599 can be 22 used by apparatus 500 for comparing the detected and modelled yaw rate.The signals received on data port 599 can be used by apparatus 500 forfiltering the result of said comparison between the detected and modelledyaw rate so as to avoid influence of rapid changes. The signals received ondata port 599 can be used by apparatus 500 for determining the influence ofexternal forces on the yaw rate based on said comparison of detected andmodelled yaw rate. The signals received on data port 599 can be used byapparatus 500 for determining a compensation torque for compensating thesteering torque of the vehicle based upon the determined influence ofexternal forces on the yaw rate. The external forces emanate from one ormore of: influence of cross sloped configuration of the road; influence oflateral wind; and influence of flat tire. A static gain for obtaining saidcompensation torque is obtained via said transfer function. The signalsreceived on data port 599 can be used by apparatus 500 for compensatingthe steering torque based upon said determined compensation torque.
Parts of the methods described herein can be performed by apparatus 500by means of data processing device 510 running the program stored inseparate memory 560 or read/write memory 550. When apparatus 500 runsthe program, parts of the methods described herein are executed.
The foregoing description of the preferred embodiments of the presentinvention has been provided for the purposes of illustration and description. ltis not intended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparent topractitioners skilled in the art. The embodiments were chosen and describedin order to best explain the principles of the invention and its practicalapplications, thereby enabling others skilled in the art to understand theinvention for various embodiments and with the various modifications as are suited to the particular use contemplated.
Claims (13)
1. A method for facilitating steering of a vehicle (1) during driving along aroad (Fl) comprising the steps of: detecting (S1) the yaw rate of the vehicle;modelling (S2) the yaw rate of the vehicle; comparing (S3) the detected andmodelled yaw rate, characterized in that the modelled yaw rate is basedupon the steering torque of the vehicle, the method further comprising thesteps of: - determining (S4) the influence of external forces on the yaw rate basedon said comparison of detected and modelled yaw rate; - based upon the determined influence of external forces on the yaw ratedetermining (S5) a compensation torque for compensating the steeringtorque of the vehicle; and - compensating (S6) the steering torque based upon said determined compensation torque.
2. A method according to claim 1, wherein the result of said comparisonbetween the detected and modelled yaw rate is filtered so as to avoidinfluence of rapid changes.
3. A method according to claim 1 or 2, wherein the modelled yaw rate isobtained via a transfer function (G(z)).
4. A method according to claim 3, wherein a static gain for obtaining saidcompensation torque is obtained via said transfer function (G(z)).
5. A method according to any preceding claims wherein said external forcesemanate from one or more of: influence of cross sloped configuration of the road; influence of Iateral wind; and influence of flat tire.
6. A system for facilitating steering of a vehicle (1) during driving along aroad (Fl) comprising means (120) for detecting the yaw rate of the vehicle;modelling means (130; 230) for modelling the yaw rate of the vehicle; means(140; 240) for comparing the detected and modelled yaw rate, characterized 24 in that the modelling means is arranged to model the yaw rate is based uponthe steering torque of the vehicle, the system further comprising means (160)for determining the influence of external forces on the yaw rate based on saidcomparison of detected and modelled yaw rate; means (170; 270) fordetermining a compensation torque for compensating the steering torque ofthe vehicle based upon the determined influence of external forces on theyaw rate; and means (180) for compensating the steering torque based uponsaid determined compensation torque.
7. A system according to claim 6, comprising filtering means (150; 250) forfiltering the result of said comparison between the detected and modelledyaw rate so as to avoid influence of rapid changes.
8. A system according to claim 6 or 7, wherein the modelling means (130;230) is arranged to obtain the modelled yaw rate via a transfer function (G(2))-
9. A system according to claim 8, wherein a static gain for obtaining saidcompensation torque is arranged to be obtained via said transfer function (G(2))-
10. A system according to any of claims 6-9, wherein said external forcesemanate from one or more of: influence of cross sloped configuration of the road; influence of lateral wind; and influence of flat tire.
11. A vehicle (1) comprising a system (I) according to any of claims 6-10.
12. A computer program (P) for facilitating steering of a vehicle during drivingalong a road, said computer program (P) comprising program code which,when run on an electronic control unit (100) or another computer (500)connected to the electronic control unit (100), causes the electronic controlunit to perform the steps according to claim 1-5.
13. A computer program product comprising a digital storage medium storingthe computer program according to claim 12.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1551564A SE539434C2 (en) | 2015-12-01 | 2015-12-01 | Method and system for facilitating steering of a vehicle while driving along a road |
| DE112016005067.4T DE112016005067T5 (en) | 2015-12-01 | 2016-11-17 | METHOD AND SYSTEM FOR FACILITATING THE STEERING OF A VEHICLE WHILE DRIVING ALONG A STREET |
| PCT/SE2016/051131 WO2017095300A1 (en) | 2015-12-01 | 2016-11-17 | Method and system for facilitating steering of a vehicle during driving along a road |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1551564A SE539434C2 (en) | 2015-12-01 | 2015-12-01 | Method and system for facilitating steering of a vehicle while driving along a road |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| SE1551564A1 true SE1551564A1 (en) | 2017-06-02 |
| SE539434C2 SE539434C2 (en) | 2017-09-19 |
Family
ID=58797406
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| SE1551564A SE539434C2 (en) | 2015-12-01 | 2015-12-01 | Method and system for facilitating steering of a vehicle while driving along a road |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE112016005067T5 (en) |
| SE (1) | SE539434C2 (en) |
| WO (1) | WO2017095300A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020001758A1 (en) | 2018-06-27 | 2020-01-02 | Volvo Truck Corporation | Method and system for controlling steering of a vehicle |
| EP4234367A1 (en) * | 2022-02-24 | 2023-08-30 | Volvo Truck Corporation | A torque vectoring control method for vehicles |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3625392A1 (en) | 1986-02-13 | 1987-08-20 | Licentia Gmbh | Control system for preventing skidding movements of a motor vehicle |
| DE4226746C1 (en) | 1992-08-13 | 1993-10-07 | Daimler Benz Ag | Method for determining a driving-dependent steering angle |
| GB2372020A (en) * | 2001-02-07 | 2002-08-14 | Lucas Industries Ltd | Haptic controller for electrically-assisted power steering in road vehicles |
| GB0106925D0 (en) * | 2001-03-20 | 2001-05-09 | Lucas Industries Ltd | Steering control during ABS split MU operation |
| FR2915447B1 (en) | 2007-04-30 | 2009-11-20 | Peugeot Citroen Automobiles Sa | METHOD OF MODELING A MOTOR VEHICLE |
| US9180908B2 (en) * | 2010-11-19 | 2015-11-10 | Magna Electronics Inc. | Lane keeping system and lane centering system |
| JP5429234B2 (en) * | 2011-03-23 | 2014-02-26 | トヨタ自動車株式会社 | Information processing apparatus for vehicle |
-
2015
- 2015-12-01 SE SE1551564A patent/SE539434C2/en not_active IP Right Cessation
-
2016
- 2016-11-17 WO PCT/SE2016/051131 patent/WO2017095300A1/en active Application Filing
- 2016-11-17 DE DE112016005067.4T patent/DE112016005067T5/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE112016005067T5 (en) | 2018-07-12 |
| SE539434C2 (en) | 2017-09-19 |
| WO2017095300A1 (en) | 2017-06-08 |
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