SE1650936A1 - Method and system for controlling dapmping of an artiulationjoint of an articulated - Google Patents

Abstract

The present invention relates to a method for controlling damping of an articulation joint of a wheeled articulated vehicle (V) travelling along a road (R), the vehicle comprising a first vehicle unit (1) having a steering wheel (SW) for steering the vehicle, a second vehicle unit (2) and an articulation joint (A) connecting the first and second vehicle units (1, 2), said first and second vehicle units being pivotable about said articulation joint (A), the articulation being controlled by means of damping members (D1, D2) arranged in connection to the articulation joint (A) for damping of the same. The method comprises the steps of: determining the steering angle (a) and/or the steering angle velocity; and, controlling the damping of the articulation joint (A) taking the thus determined steering angle and/or steering angle velocity into account.The present invention also relates to a system for controlling driving of a vehicle along a road. The present invention also relates to a vehicle. The present invention also relates to a computer program and a computer program product.

Description

I\/IETHOD AND SYSTEM FOR CONTROLLING DAPMPING OF ANARTIULATION JOINT OF AN ARTICULATED TECHNICAL FIELD The invention relates to a method for controlling damping of an articulationjoint of a wheeled articulated vehicle travelling along a road according to thepreamble of claim 1. The invention also relates to a system for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road. The invention also relates to a vehicle. The invention in additionrelates to a computer program and a computer program product.

BACKGROUND ART So called articulated buses allow a longer legal length than rigid-bodiedbuses, and thus have a higher passenger capacity. Such articulated busescomprise so called pusher buses having the wheel axle furthest back as thedriving axle, with the engine placed in the back as well. This is done to makemore room for passengers and a better distribution of them in the bus body.l\/lany challenges come with this type of design as it makes the weight of thevehicle uneven with a great amount in the back of the bus on the driving axle,leaving the middle axle with less weight, pressure and grip. This constructionleads to high risks of the bus being folded when making a turn with thevehicle or when driving downhill on a slippery slope, especially incombination if making a turn. lf the vehicle would get folded it may have to bepulled apart again with external assistance. This construction also leads togeneral dangerous instability of the whole vehicle since it is hard tomanoeuvre. To prevent the vehicle from being folded a well-balanced damping system in the articulation is of great importance.

One solution is to control the damping such that the damping is increased atincreased vehicle velocity. The damping is also controlled based upon theangle in the articulation joint and in certain situations the angle velocity of thearticulation joint.

Such a solution may work well in normal driving situations. ln someconditions unsafe situations, such as a jack-knife situation may occur. E.g.for slippery roads with an inclination such problems may arise. One knownstrategy for dealing with low friction is to reduce the torque on the driving axleto prevent the mid axle from being pushed sideways and cause a jack-knifesituation. The vehicle will then roll by its own motion until grip is improved forall wheels and the wheels have the same velocity, wherein the torque can beapplied from the driving axle again. This solution may however not besufficient for an articulated bus and the rear part of the bus can still keep onskidding sideways and put the vehicle in an unfortunate position, such as a jack-knife situation.

WO2008073045 discloses damping of the articulation of an articulatedvehicle based on angle in the articulation joint and speed of the vehicle.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road which facilitates improving safety and drivability.

Another object of the present invention is to provide a system for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road which facilitates improving safety and drivability.

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 c|aims.Preferred embodiments of the method and the system are defined inappended dependent c|aims.

Specifically an object of the invention is achieved by a method for contro||ingdamping of an articulation joint of a wheeled articu|ated vehicle travellingalong a road. The vehicle comprises a first vehicle unit having a steeringwheel for steering the vehicle, a second vehicle unit and an articulation jointconnecting the first and second vehicle unit, said first and second vehicleunits being pivotable about said articulation joint. The articulation is controlledby means of damping members arranged in connection to the articulationjoint for damping of the same. The method comprises the steps of:determining the steering angle and/or the steering angle velocity; and,contro||ing the damping of the articulation joint taking the thus determinedsteering angle and/or steering angle velocity into account.

The step of determining the steering angle comprises according to an embodiment utilizing any suitable steering angle sensor.

The step of determining the steering angle velocity comprises according toan embodiment utilizing any suitable steering angle velocity sensor.

The step of contro||ing the damping of the articulation joint taking the thusdetermined steering angle and/or steering angle velocity into accountcomprises according to an embodiment contro||ing the damping of thearticulation joint based upon thus determined steering angle and/or steeringangle velocity. The damping of the articulation joint may thus be adaptedbased upon thus determined steering angle and/or steering angle velocity.

The step of contro||ing the damping of the articulation joint may be obtainedin any suitable way by any suitable means. The step of contro||ing thedamping of the articulation joint comprises according to an embodiment utilizing an electronic control unit for controlling the damping of the dampingmembers. The damping members comprise according to an embodimenthydraulic cylinders with pistons being movable based upon hydraulic fluid,e.g. oil. The damping members comprises valve members being controllablebetween an open position allowing flow of hydraulic fluid providing a lowerdamping and a closed position preventing flow of hydraulic fluid essentiallylocking the articulation joint and thus providing an essentially stiff damping.

By thus controlling the damping of the articulation joint taking the thusdetermined steering angle and/or steering angle velocity into account saferdriving of the articulated vehicle is facilitated in that proactive damping isobtained since actual turn of the vehicle and possible pivoting effect on thesecond vehicle unit, i.e. the rear vehicle unit, will be delayed so that adapteddamping of the articulation joint has been effected before such pivotingoccurs. The articulation angle, i.e. the angle between the first and secondvehicle unit, will in a curve be essentially proportional to the steering anglebut will appear with a delay compared to the steering angle, whereinproactive damping is facilitated by thus damping the articulation joint inconnection to the steering angle indicating a turn. Hereby the damping maybe controlled based upon situations where the damping should be higherindependent of the vehicle speed, i.e. also at lower speeds, in order toprevent the rear vehicle unit from skidding sideways in an undesired andunsafe manner, e.g. creating a so called jack-knife situation and/or creatinguncomfortable and dangerous oscillations of the rear vehicle unit which maye.g. lead to the vehicle being transversally positioned on the road blockingthe traffic and/or causing an accident, or the rear vehicle unit colliding withanother vehicle during drive. Such a situation may be on a slippery road, e.g.in a downhill slope in connection to a curve and/or due to the rear vehicle unit(or front vehicle unit) having a load which is higher than the load of theintermediate unit of the vehicle, wherein in a relatively higher force of the rearvehicle unit due to e.g. an instability. Such a situation may also occur by a sudden manoeuver by the driver trying to avoid an obstacle, or a sudden brake in a curve. By thus controlling the damping of the articulation jointtaking the thus determined steering angle and/or steering angle velocity intoaccount manoeuvring of the vehicle may be improved e.g. by controlling thedamping such that an increased damping is obtained also at lower speedswhen it is determined by the steering angle and/or steering angle velocity thatthe vehicle is driving in a straight forward direction. Thus by controlling thedamping of the articulation joint taking the thus determined steering angleand/or steering angle velocity into account safer driving and improvedmanoeuvrability of the vehicle is facilitated.

According to an embodiment of the method the step of taking said steeringangle into account comprises the step of controlling said damping to arelatively higher damping if said steering angle has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period, and controlling said damping to a damping for allowing thevehicle to safely entering into a curve if said steering angle has been heldwithin limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

According to an embodiment the time period for the delay between a steeringwheel action such as a change in steering angle indicating a turn and acorresponding change in the angle of the articulation joint is determinedbased upon the vehicle velocity and the distance between the steerable frontwheels of the vehicle and the articulation joint. The thus determined delay isaccording to an embodiment used as information for when to adapt thedamping of the articulation joint.

The method thus comprises the step of determining the delay of change ofsteering angle and corresponding change of articulation angle based uponvehicle velocity and distance between steerable front wheels of the vehiclesand articulation joint. The vehicle velocity is according to an embodiment the mean velocity.

The method thus comprises the step of controlling the damping of thearticulation joint taking the delay of change of steering angle andcorresponding change of articulation angle into account.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle has been held within limits indicatingtravelling in a substantially straight forward direction for a certain time period.By controlling said damping to a relatively higher damping if said steeringangle has been held within limits indicating travelling in a substantiallystraight fon/vard direction for a certain time period drivability may be improvedin that a higher damping is obtained independent of the vehicles speed and thus even at lower vehicle speeds.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle has been held within limits indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod. By controlling said damping to a damping for allowing the vehicle tosafely entering into a curve if said steering angle has been held within limitsindicating intention to travel in a changing direction, indicating a curve, for acertain time period proactive adaption of the damping in order to improvesafety and drivability is facilitated. Hereby a situation where the rear vehicleunit skids sideways in an undesired and unsafe manner, e.g. creating a socalled jack-knife situation and/or uncomfortable and dangerous oscillations ofthe rear vehicle unit which may e.g. lead to the vehicle being transversallypositioned on the road blocking the traffic and/or causing an accident, or therear vehicle unit colliding with another vehicle during drive may be avoided.

According to an embodiment of the method the step of taking said steeringangle velocity into account comprises the step of controlling said damping toa relatively higher damping if said steering angle velocity has been heldwithin limits indicating travelling in a substantially straight forward direction fora certain time period, controlling said damping to a damping for allowing thevehicle to safely entering into a curve if said steering angle velocity exceeds a limit indicating intention to travel in a changing direction, indicating a curve,for a certain time period, and controlling said damping to a damping forallowing the vehicle to safely enter into a turn manoeuvre if said steeringangle velocity indicates a, compared to said steering angle velocity indicatinga curve, higher steering angle velocity.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle velocity has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period. By controlling said damping to a relatively higher damping if saidsteering angle has been held within limits indicating travelling in asubstantially straight forward direction for a certain time period drivability maybe improved in that a higher damping is obtained independent of the vehiclesspeed and thus even at lower speeds.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle velocity exceeds a limit indicating intentionto travel in a changing direction, indicating a curve, for a certain time period.By controlling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle velocity exceeds a limit indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod proactive adaption of the damping in order to improve safety anddrivability is facilitated. Hereby a situation where the rear vehicle unit skidssideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or uncomfortable and dangerous oscillations of the rearvehicle unit which may e.g. lead to the vehicle being transversally positionedon the road blocking the traffic and/or causing an accident, or the rear vehicleunit colliding with another vehicle during drive may be avoided.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle velocity indicates a, compared to saidsteering angle velocity indicating a curve, higher steering angle velocity. Bycontrolling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre if said steering angle velocity indicates a, compared tosaid steering angle velocity indicating a curve, higher steering angle velocityproactive adaption of the damping in order to improve safety and drivability isfacilitated. Hereby a situation where the rear vehicle unit skids sideways in anundesired and unsafe manner, e.g. creating a so called jack-knife situationand/or uncomfortable and dangerous oscillations of the rear vehicle unitwhich may e.g. lead to the vehicle being transversally positioned on the roadblocking the traffic and/or causing an accident, or the rear vehicle unitcolliding with another vehicle during drive may be avoided.

According to an embodiment the method further comprises the steps of:determining and comparing the velocity of the vehicle wheels; and, if thevelocity of all wheels are about the same taking this as an indication of thevehicle travelling in a straight forward direction, controlling the dampingaccordingly, and, if the velocity of the vehicle front wheels is determined todiffer to a certain extent, taking this as indication of the vehicle entering into acurve and controlling the damping accordingly.

According to this embodiment the method thus comprises the steps of:determining the velocity of the vehicle wheels of the vehicle; and comparting the thus determined velocity of the vehicle wheels of the vehicle.

According to this embodiment the method thus comprises the step ofdetermining whether all wheels are about the same.

The step of controlling the damping accordingly if it has been indicated thatthe vehicle travelling in a straight forward direction based on the velocity of allwheels being about the same refers to controlling said damping to a relativelyhigher damping.

According to an embodiment the method further comprises the steps of:determining the extension of the road comprising curvature and topologyalong which the vehicle is travelling; and, taking the thus determined extension of the road into account when controlling the damping of the articulation joint.

The step of determining the extension of the road comprising curvature andtopology along which the vehicle is travelling comprises the step of detectingthe trajectory of the road comprising curvature and topology of the road. Thestep of detecting the trajectory of the road comprises utilizing any suitabledetector means comprising any suitable detector such as one or morecamera units, one or more laser scanner units, one or more radar units or thelike. The step of detecting slopes may comprise a gyro for detecting the degree of inclination.

The step of determining the extension of the road comprising curvature andtopology along which the vehicle is travelling comprises the step ofdetermining the current position of the vehicle and extracted map informationof the extension of the road along which the vehicle is travelling. The step ofdetermining the current position of the vehicle comprises according to anembodiment utilizing a Global Navigation Satellite System, GNSS, e.g. aglobal positioning system, GPS, for continuously determining the position ofthe vehicle and thus whether the vehicle is moving.

By thus determining the extension of the road comprising curvature andtopology along which the vehicle is travelling relevant information foroptimizing control of the damping of the articulation joint is obtained and maybe obtained in time to be able to proactively take action in order to have adamping that will be safe for e.g. an upcoming curve when driving in a slope.By taking the thus determined extension of the road into account whencontrolling the damping of the articulation joint proactive adaption of thedamping in order to improve safety and drivability is facilitated. Hereby asituation where the rear vehicle unit skids sideways in an undesired andunsafe manner, e.g. creating a so called jack-knife situation and/oruncomfortable and dangerous oscillations of the rear vehicle unit which may e.g. lead to the vehicle being transversally positioned on the road blocking the traffic and/or causing an accident, or the rear vehicle unit colliding with another vehicle during drive may be avoided.

According to an embodiment the method further comprises the steps of:determining external conditions comprising weather conditions and/or roadconditions in connection to the vehicle driving along said road; and taking thethus determined weather conditions and/or road conditions into accountwhen controlling the damping of the articulation joint.

The step of determining the weather conditions comprises determiningweather conditions along the road on which the wheeled articulated vehicle istravelling and in connection to the occasion on which the vehicle is travellingalong said road. The step of determining the weather conditions comprisesaccording to an embodiment utilizing weather sensors comprising anysuitable rain sensor/precipitation sensor e.g. arranged in connection to thewindshield, any suitable temperature sensor, any suitable wind sensor or thelike. The step of determining the weather conditions comprises according toan embodiment utilizing external weather data from any externalprovider/server with which the vehicle, i.e. a control unit/server unit or the like of the vehicle, may establish contact.

Thus determined weather conditions may comprise rain and extent of rain,snow and extent of snow, current temperature, wind conditions, extent of wind and direction of wind or the like.

By thus taking the determined weather conditions into account whencontrolling the damping of the articulation joint proactive adaption of thedamping in order to improve safety and drivability is facilitated.

The step of determining the road conditions comprises determining roadconditions along the road on which the wheeled articulated vehicle istravelling and in connection to the occasion on which the vehicle is travellingalong said road. The step of determining the road conditions comprisesaccording to an embodiment utilizing any suitable detector means comprising 11 any suitable detector unit for detecting the surface of the road along whichthe vehicle is travelling such as one or more camera units and/or one or morelaser scanner units and/or one or more radar units. The step of determiningthe road conditions comprises according to an embodiment utilizing externaldata from any external provider/server with which the vehicle, i.e. a control unit/server unit or the like of the vehicle, may establish contact.

Thus determined road conditions may comprise slippery road due to e.g. iceon the road, snow on the road, oil on the road, gravel on the road, water onthe road, curves of the road, slopes of the road and/or other road conditionsthat may affect driving along the road.

By thus taking the determined road conditions into account when controllingthe damping of the articulation joint proactive adaption of the damping inorder to improve safety and drivability is facilitated. Hereby a situation wherethe rear vehicle unit skids sideways in an undesired and unsafe manner, e.g.creating a so called jack-knife situation and/or uncomfortable and dangerousoscillations of the rear vehicle unit which may e.g. lead to the vehicle beingtransversally positioned on the road blocking the traffic and/or causing anaccident, or the rear vehicle unit colliding with another vehicle during drivemay be avoided.

By thus taking the determined weather conditions and road conditions intoaccount when controlling the damping of the articulation joint proactiveadaption of the damping in order to improve safety and drivability isfacilitated. Hereby a situation where the rear vehicle unit skids sideways in anundesired and unsafe manner, e.g. creating a so called jack-knife situationand/or uncomfortable and dangerous oscillations of the rear vehicle unitwhich may e.g. lead to the vehicle being transversally positioned on the roadblocking the traffic and/or causing an accident, or the rear vehicle unitcolliding with another vehicle during drive may be avoided. 12 According to an embodiment of the method said wheeled articulated vehicleis an articulated bus. According to an embodiment the articulated bus is a socalled accordion bus. According to an embodiment of the method saidwheeled articulated vehicle is an articulated passenger vehicle. According toan embodiment of the method said wheeled articulated vehicle is a bi-articulated bus having two articulation joints and thus a third vehicle unit, i.e.a first vehicle unit being the front vehicle unit, a second vehicle unit being therear vehicle unit, and a third vehicle unit being an intermediate vehicle unit,wherein a first articulation joint connects the front and intermediate vehicleunits which are pivotable about said first articulation joint, and a secondarticulation joint connects the intermediate and rear vehicle units which arepivotable about said second articulation joint. The articulation for the bi-articulated bus is arranged to be controlled by means of damping membersarranged in connection to the first articulation joint and damping members arranged in connection to the second articulation joint.

A system for controlling damping of an articulation joint of a wheeledarticulated vehicle travelling along a road. The vehicle comprises a firstvehicle unit having a steering wheel for steering the vehicle, a second vehicleunit and an articulation joint connecting the first and second vehicle unit, saidfirst and second vehicle units being pivotable about said articulation joint. Thearticulation is arranged to be controlled by means of damping membersarranged in connection to the articulation joint for damping of the same. Thesystem comprises means for determining the steering angle and/or meansfor determining the steering angle velocity; and, means for controlling thedamping of the articulation joint taking the thus determined steering angle and/or steering angle velocity into account.

The first vehicle unit is according to an embodiment the front vehicle unit.The second vehicle unit is according to an embodiment the rear vehicle unit.

According to an embodiment of the system the means for taking said steering angle into account comprises means for controlling said damping to a 13 relatively higher damping if said steering angle has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period, and means for controlling said damping to a damping forallowing the vehicle to safely entering into a curve if said steering angle hasbeen held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

Thus, according to an embodiment the system comprises means fordetermining if said steering angle has been held within limits indicatingintention to travel in a changing direction, indicating a curve, for a certain time penod.

Thus, according to an embodiment the system comprises means fordetermining if said steering angle has been held within limits indicatingintention to travel in a changing direction, indicating a curve, for a certain time penod.

According to an embodiment of the system the means for taking said steeringangle velocity into account comprises means for controlling said damping toa relatively higher damping if said steering angle velocity has been heldwithin limits indicating travelling in a substantially straight forward direction fora certain time period, and means for controlling said damping to a dampingfor allowing the vehicle to safely entering into a curve if said steering anglevelocity exceeds a limit indicating intention to travel in a changing direction,indicating a curve, for a certain time period, and means for controlling saiddamping to a damping for allowing the vehicle to safely enter into a turnmanoeuvre if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity.

Thus according to an embodiment the system comprises means fordetermining if said steering angle velocity has been held within limitsindicating intention to travel in a changing direction, indicating a curve, for a certain time period. 14 Thus according to an embodiment the system comprises means fordetermining if said steering angle velocity exceeds a limit indicating intentionto travel in a changing direction, indicating a curve, for a certain time period.

Thus according to an embodiment the system comprises means fordetermining if said steering angle velocity indicates a, compared to saidsteering angle velocity indicating a curve, higher steering angle velocity. Bycontrolling said damping to a damping for allowing the vehicle to safely enterinto a turn manoeuvre if said steering angle velocity indicates a, compared tosaid steering angle velocity indicating a curve, higher steering angle velocity.

According to an embodiment the system further comprises means fordetermining and comparing the velocity of the vehicle wheels; and means fortaking it as an indication of the vehicle travelling in a straight forward directionif the velocity of all wheels are about the same, the damping being arrangedto be controlled accordingly, and, means for taking it as indication of thevehicle entering into a curve and controlling the damping accordingly if thevelocity of the vehicle front wheels is determined to differ to a certain extent.

According to an embodiment the system further comprises means fordetermining the extension of the road comprising curvature and topologyalong which the vehicle is travelling; and, means for taking the thusdetermined extension of the road into account when controlling the dampingof the articulation joint.

According to an embodiment the system further comprises means fordetermining external conditions comprising means for determining weatherconditions and/or means for determining road conditions in connection to thevehicle driving along said road; and means for taking the thus determinedweather conditions and/or road conditions into account when controlling the damping of the articulation joint.

According to an embodiment the system also comprises means fordetermining the vehicle speed. The means for determining the vehicle speedmay comprise the speedometer of the vehicle.

According to an embodiment of the system said wheeled articulated vehicleis an articulated bus.

The system for controlling damping of an articulation joint of a wheeledarticulated vehicle travelling along a road is adapted to perform the methodsas set out herein.

The system according to the invention has the advantages according to thecorresponding method.

Specifically an object of the invention is achieved by a vehicle comprising asystem as set out herein.

Specifically an object of the invention is achieved by a computer program forcontrolling damping of an articulation joint of a wheeled articulated vehicletravelling along a road, said computer program comprising program codewhich, when run on an electronic control unit or another computer connectedto the electronic control unit, causes the electronic control unit to performmethods 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 thefollowing detailed description when read in conjunction with theaccompanying drawings, wherein like reference characters refer to like parts throughout the several views, and in which: 16 Fig. fa schematically illustrates a side view of a wheeled articulated vehicle having a front and rear vehicle unit according to the present invention; Fig. fb schematically illustrates a plan view of the articulated vehicle in fig. fa; Fig. fc schematically illustrates a plan view of the articulated vehicle in fig. fbwhere the rear vehicle unit has pivoted about an articulation joint relative tothe front vehicle unit; Fig. fd schematically illustrates a side view of the articulated vehicle in fig. f in a downhill slope; Fig. 2 schematically illustrates a plan view of a part of the articulated vehicle in fig. fb with the articulation joint; Fig. 3 schematically illustrates a block diagram of a system for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road according to an embodiment of the present invention; Fig. 4 schematically illustrates a block diagram of a method for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road according to an embodiment of the present invention; and Fig. 5 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. 17 Hereinafter the term “certain time period” may be a “determined time period” and where applicable a “predetermined time period”.

Fig. 1a schematically illustrates a side view of a wheeled articulated vehicleaccording to the present invention. The exemplified vehicle V is an articulatedbus in the shape of an accordion bus. The vehicle comprises a system l forcontrolling damping of an articulation joint of the wheeled articulated vehicleV travelling along a road R according to an embodiment of the present invenfion.

The vehicle V comprises a first vehicle unit 1 having a steering wheel SW forsteering the vehicle and a second vehicle unit 2. The vehicle V has anintermediate unit 3 between the first and second vehicle units 1, 2. Theintermediate unit 3 comprises an articulation joint A schematically illustratedin fig. 1b and 1c and schematically in more detail in fig. 2. The intermediate unit 3 comprises an accordion configuration.

The first vehicle unit 1 comprises a set of front wheels of which the left frontwheel WL1 is shown, and a set of intermediate wheels of which the leftintermediate wheel WL3 is shown. The second vehicle unit 2 has a set ofrear wheel of which the left rear wheel W2L is shown. The rear wheels constitute the drive wheels of the vehicle V.

The vehicle V comprises drive member E for operating the vehicle by drivingthe drive wheels. The drive member E may be any suitable drive member E.

Said first vehicle unit 1 constitutes the front vehicle unit and the second vehicle unit 2 constitutes the rear vehicle unit.

Fig. 1b schematically illustrates a plan view of the articulated vehicle V in fig.1a. The articulation joint A is connecting the first and second vehicle units 1,2. The first and second vehicle units 1, 2 are pivotable about said articulation joint A. 18 The vehicle V has a front wheeled axel X1 arranged in the first vehicle unit 1.The front axle X1 is supporting said set of left and right front wheels W1L,W1R. The vehicle V has a powered rear wheeled axel X2 arranged in thesecond vehicle unit 2. The powered rear wheeled axel X2 is also called thedrive axle X2. The drive axle X2 is supporting said set of left and right rearwheels W2L, W2R. The vehicle V has an intermediate wheeled axel X3arranged in the first vehicle unit 1. The intermediate axle X3 is supportingsaid set of left and right intermediate wheels W3L, W3R.

The first vehicle unit 1 comprises a first vehicle frame 1A, 1B to which thefront axle X1 and intermediate axle X3 are connected. The second vehicleunit 2 comprises a second vehicle frame 2A, 2B to which the rear axle X2 isconnected.

The steering wheel SW is connected to the front wheels W1L, W1R andconfigured to steer the front wheels W1 L, W1R by turning the steering wheelchanging the steering wheel angle. By changing the steering wheel angle acorresponding change in the front wheels W1 L, W1R will be generated. ln fig. 1b the front wheels W1L, W1R have been turned by means ofchanging the steering angle to a steering angle d.

Fig. 1c schematically illustrates a plan view of the articulated vehicle V in fig.1b where the second vehicle unit 2 has pivoted about the articulation joint Arelative to the first vehicle unit 1 such that an articulation angle ß is formed.

By looking at the present steering wheel angle d and what the that angle hasbeen for some time it can be determined whether the vehicle is said to travelin a straight line and being in a straight position or not. lf the steering anglehas been the same for a certain time the vehicle can be defined as travellingin a straight forward direction. Also, by looking at the angle velocity acomplementary indication of the movement of the vehicle can be made, e.g.if higher than zero an upcoming turn can be suspected. Additionally, datasuch as wheel speed can also help confirming the positioning of the vehicle. 19 lf all wheels have the same speed the vehicle is with a high probabilitytravelling in a straight line. lf the speed of one of the front wheels is suddenlyreduced the vehicle can be said to start going into a curve. lf the vehicle speed is known and the steering angle is known it can also beknown when articulation will need to have a certain curvature /angle to be inline with the road. lf it is known when the articulation will have a certain anglethe damping can be ramped up ahead of time, i.e. proactively, and increasestability of the vehicle. This may according to an embodiment be determinedwith the equation below. ß(t0 + At) oc a(t0)ß = articulation angle, a = steering angle,to = time from where steering wheel is turned AExample of rough estimation for finding At: At = TSv As = distance between steered front wheels and articulationjoint A\7 = mean velocity of vehicle A Global Navigation Satellite System, GNSS, e.g. a global positioningsystem, GPS, for continuously determining the position of the vehicle isaccording to an embodiment applied to complement this algorithm with 2D or3D map data. When the vehicle is known to travel in a forwards direction on astraight road a much higher damping can be applied, and more stability for the vehicle as a whole is achieved. lf damping is increased sooner or later than the actual need, the driver willnot achieve the curvature of the vehicle that needed to drive the full curve. ltis dangerous to stiffen the articulation at the wrong time; exact timing for theamount of damping for when going into, during and going out of a curve, iscrucial. E.g. when the vehicle is turning the articulation cannot be totallystiffened, the joint must be able to move. lf the road is known to be straight orthe curve is distributed so that the articulation angle can remain essentially constant for a certain time period, comparably more damping can be applied.

Fig. 1b and 1c illustrates the time delay between the angle change of thesteering wheel angle o illustrated in fig. 1b with the front wheels turned to anangle change to an angle ß in the articulation joint A illustrated in fig. 1c as aconsequence of the steering wheel angle change in fig. 1b.

Fig. 1d schematically illustrates a side view of the articulated vehicle V in fig. 1 in a downhill slope of the road R. The slope has an inclination y.

Thus according to the invention the damping of the articulation joint A iscontrolled taking the thus determined steering angle and/or steering anglevelocity into account. ln the example in fig. 1d also the slope and the roadcondition is taken into account.

By proactive increased damping according to the present invention in thearticulation joint A in hilly topology as in fig. 1d prevention of the vehiclebending /get critical articulation angles and end up in safety critical situationsis obtained. Hereby a more progressive, enhanced and proactive dampingstrategy can be applied for low speeds and low angles (and low anglespeeds) where needed, as in this case with the vehicle travelling in a downhill slope.

Fig. 2 schematically illustrates a plan view of a part of the articulated vehicle in fig. 1b with the articulation joint A.

The articulation is controlled by means of damping members D1, D2arranged in connection to the articulation joint. Controlling the damping of thearticulation joint A comprises according to an embodiment utilizing anelectronic control unit ECU for controlling the damping of the dampingmembers D1, D2.

The damping members D1, D2 here constitutes a first damping member D1and a second damping member D2.

The damping members D1, D2 comprise according to an embodimenthydraulic cylinders C1, G2 with pistons P1, P2 being movable based upon 21 hydraulic fluid, e.g. oil. The damping members D1, D2 comprise valvemembers V1, V2 being controllable between an open position allowing flowof hydraulic fluid via a fluid line F1, F2 providing a lower damping and aclosed position preventing flow of hydraulic fluid essentially locking the articulation joint A and thus providing an essentially stiff damping.

Controlling the damping of the articulation joint A comprises according to thisembodiment utilizing an electronic control unit ECU for controlling thedamping of the damping members D1, D2. The electronic control unit isoperably connected to the respective valve V1, V2 for receiving informationabout current damping and sending signals representing data for controlling the valves so as to adapt the damping of the damping members D1, D2.The damping members D1, D2 may be controlled individually.

The articulation joint comprises a rotatable member l\/I being rotatably journalled in said intermediate unit 3.

The cylinder C1, G2 are connected to the second vehicle unit at one end andto the rotatable member l\/I at the opposite end via the pistons P1, P2 so as toallow the first and second vehicle units 1, 2 to pivot about said articulation joint A.

Fig. 3 schematically illustrates a block diagram of a system l for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road according to an embodiment of the present invention.

The vehicle comprises a first vehicle unit having a steering wheel for steeringthe vehicle, a second vehicle unit and an articulation joint connecting the firstand second vehicle unit, said first and second vehicle units being pivotableabout said articulation joint. The articulation is controlled by means ofdamping members arranged in connection to the articulation joint.

The system I comprises an electronic control unit 100. 22 The system I comprises means 110 for determining the steering angle. Themeans 110 for determining the steering angle comprises any suitablesteering angle sensor.

According to an embodiment the means 110 for determining the steeringangle comprises means 112 for determining if said steering angle has beenheld within limits indicating travelling in a substantially straight fon/varddirection for a certain time period.

According to an embodiment the means 110 for determining the steeringangle comprises means 114 for determining if said steering angle has beenheld within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

The system I comprises means 120 for determining the steering anglevelocity. The means 120 for determining the steering angle velocitycomprises any suitable steering angle velocity sensor. According to anembodiment means 120 for determining the steering angle velocitycomprises any suitable steering angle sensor, wherein the steering anglevelocity is arranged to be determined by continuously or intermittentlydetermining the steering angle with said steering angle sensor.

According to an embodiment the means 120 for determining the steeringangle velocity comprises means 122 for determining if said steering anglevelocity has been held within limits indicating travelling in a substantiallystraight forward direction for a certain time period.

According to an embodiment the means 120 for determining the steeringangle velocity comprises means 124 for determining if said steering anglevelocity exceeds a limit indicating intention to travel in a changing direction,indicating a curve, for a certain time period.

According to an embodiment the means 120 for determining the steeringangle velocity comprises means 126 for determining if said steering angle 23 velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity.

The system I comprises means 130 for controlling the damping of thearticulation joint.

The means 130 for controlling the damping of the articulation joint comprisesmeans 131 for controlling the damping of the articulation joint taking the thusdetermined steering angle into account.

The means 130 for controlling the damping of the articulation joint comprisesmeans 132 for controlling the damping of the articulation joint taking the thusdetermined steering angle velocity into account.

The means 130 for controlling the damping of the articulation joint comprisesmeans 131, 132 for controlling the damping of the articulation joint taking thethus determined steering angle and/or steering angle velocity into account.

According to an embodiment of the system I the means 131 for taking saidsteering angle into account comprises means 131a for controlling saiddamping to a relatively higher damping if said steering angle has been heldwithin limits indicating travelling in a substantially straight forward direction fora certain time period.

According to an embodiment of the system I the means 131 for taking saidsteering angle into account comprises means 131b for controlling saiddamping to a damping for allowing the vehicle to safely entering into a curveif said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

According to an embodiment of the system I the means 132 for taking saidsteering angle velocity into account comprises means 132a for controllingsaid damping to a relatively higher damping if said steering angle velocity hasbeen held within limits indicating travelling in a substantially straight forwarddirection for a certain time period. 24 According to an embodiment of the system I the means 132 for taking saidsteering angle velocity into account comprises means 132b for contro||ingsaid damping to a damping for allowing the vehicle to safely entering into acurve if said steering angle velocity exceeds a limit indicating intention totravel in a changing direction, indicating a curve, for a certain time period.The means 132b for contro||ing said damping to a relatively higher dampingis according to an embodiment arranged to control said damping to arelatively higher damping if said steering angle velocity has been held withinlimits indicating travelling in an evenly distributed curve, distributed so thatthe articulation can have the same angle for a certain time period.

According to an embodiment of the system I the means 132 for taking saidsteering angle velocity into account comprises means 132c for contro||ingsaid damping to a damping for allowing the vehicle to safely enter into a turnmanoeuvre if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity.

According to an embodiment the system I further comprises means 140 fordetermining the velocity of the vehicle wheels. The means 140 fordetermining the velocity of the vehicle wheels may comprise any suitable sensor for determining speed of wheels.

According to an embodiment the system I further comprises means 150 forcomparing the velocity of the vehicle wheels. The means 150 for comparingthe velocity of the vehicle wheels may comprise any suitable unit forcomparing data from the means 140. The means 150 for comparing thevelocity of the vehicle wheels is according to an embodiment comprised in the electronic control unit.

The means 130 for contro||ing the damping of the articulation joint comprisesmeans 133 for contro||ing the damping of the articulation joint taking the thus determined velocity of the vehicle wheels into account.

The means 140 for determining the velocity of the vehicle wheels comprisesmeans 142 for determining if the velocity of all wheels are about the samebased on the comparison of the velocity of the vehicle wheels.

The means 140 for determining the velocity of the vehicle wheels comprisesmeans 144 for determining if the velocity of the vehicle front wheels isdetermined to differ to a certain extent based on the comparison of thevelocity of the vehicle wheels.

According to an embodiment of the system I the means 133 for taking saiddetermined velocity of the vehicle wheels into account comprises means133a for controlling said damping to a relatively higher damping if the velocityof all wheels are about the same indicating travelling in a substantiallystraight forward direction for a certain time period.

According to an embodiment of the system I the means 133 for taking saiddetermined velocity of the vehicle wheels into account comprises means133b for controlling said damping to a damping for allowing the vehicle tosafely entering into a curve if the velocity of the vehicle front wheels isdetermined to differ to a certain extent indicating entering into a curve for a certain time period.

According to an embodiment the means 133 for taking said determinedvelocity of the vehicle wheels into account is arranged to control the dampingto a relatively higher damping if the vehicle is in a curve having an extensionsuch that a relatively constant relationship between the speed of the outer wheels and the speed of the inner wheels of the vehicle.

According to an embodiment the system further comprises means 160 fordetermining the extension of the road comprising curvature and topologyalong which the vehicle is travelling.

The means 160 for determining the extension of the road comprisingcurvature and topology along which the vehicle is travelling comprises means 26 162 for detecting the trajectory of the road comprising curvature and topologyof the road. The means 162 for detecting the trajectory of the road comprisesany suitable detector means comprising any suitable detector such as one ormore camera units, one or more laser scanner units, one or more radar unitsor the like. The means 160 for slopes may comprise a gyro for detecting the degree of inclination.

The means 160 for determining the extension of the road comprisingcurvature and topology along which the vehicle is travelling comprises means164 for determining the current position of the vehicle and extracted mapinformation of the extension of the road along which the vehicle is travelling.

The means 164 for determining the current position of the vehicle andextracted map information of the extension of the road along which thevehicle is travelling comprises according to an embodiment a mapinformation unit 164a comprising map data comprising information about thetrajectory of the road on which the vehicle is travelling comprising curves,slopes and the like.

The means 164 for determining the current position of the vehicle andextracted map information of the extension of the road along which thevehicle is travelling comprises means 164b for determining the currentposition of the vehicle. The means 164b for determining the current positionof the vehicle comprises according to an embodiment utilizing a GlobalNavigation satellite System, GNSS, e.g. a global positioning system, GPS,for continuously determining the position of the vehicle and thus whether the vehicle is moving.

The means 130 for controlling the damping of the articulation joint comprisesmeans 134 for controlling the damping of the articulation joint taking the thusdetermined extension of the road into account when controlling the dampingof the articulation joint. 27 According to an embodiment the system I further comprises means 170 fordetermining external conditions comprising weather conditions and/or roadconditions in connection to the vehicle driving along said road.

The means 170 for determining external conditions comprises means 172 fordetermining weather conditions in connection to the vehicle driving along said road.

The means 172 for determining weather conditions in connection to thevehicle driving along said road may comprise any suitable means for determining weather conditions.

The means 172 for determining weather conditions in connection to thevehicle driving along said road comprises one or more weather sensor units.The weather sensor units may comprise one or more rain sensor units. Theweather sensor units may comprise one or more temperature sensor units.

The weather sensor units may comprise one or more wind sensor units.

The means 172 for determining weather conditions in connection to thevehicle driving along said road comprises according to an embodimentmeans for extracting external weather data from one or more externalweather data units comprising any suitable external server unit. The means172 for determining weather conditions in connection to the vehicle drivingalong said road comprises one or more external weather data units.

Thus determined weather conditions may comprise rain and extent of rain, snow and extent of snow, current temperature, wind conditions or the like.

The means 170 for determining external conditions comprises means 174 fordetermining road conditions in connection to the vehicle driving along saidroad.

The means 174 for determining road conditions in connection to the vehicledriving along said road comprises means for detecting road conditions inconnection to the vehicle driving along said road. The means for detecting 28 road conditions comprises any suitable detector unit for detecting the surfaceof the road along which the vehicle is travelling such as one or more camera units and/or one or more laser scanner units and/or one or more radar units.

The means 174 for determining road conditions in connection to the vehicledriving along said road comprises means for extracting information aboutroad conditions from one or more external units comprising any suitable server unit.

Thus determined road conditions may comprise slippery road due to e.g. iceon the road, snow on the road, oil on the road, gravel on the road, water onthe road, curves of the road or other road conditions that may affect driving along the road.

The means 130 for controlling the damping of the articulation joint comprisesmeans 135 for controlling the damping of the articulation joint taking the thusdetermined weather conditions into account when controlling the damping of the articulation joint.

The means 130 for controlling the damping of the articulation joint comprisesmeans 136 for controlling the damping of the articulation joint taking the thusdetermined road conditions into account when controlling the damping of the articulation joint.

According to an embodiment the system also comprises means 180 fordetermining the vehicle speed. The means 180 for determining the vehiclespeed may comprise the speedometer of the vehicle. The vehicle speed maybe used for determining when e.g. increased damping is supposed to beactivated.

According to an embodiment of the system said wheeled articulated vehicleis an articulated bus.

The electronic control unit 100 is operably connected to the means 110 for determining the steering angle via a link 10. The electronic control unit 100 is 29 via the link 10 arranged to receive a signal from said means 110 representing data for steering angle.

The electronic control unit 100 is operably connected to the means 112 fordetermining if said steering angle has been held within limits indicatingtravelling in a substantially straight forward direction for a certain time periodvia a link 12a. The electronic control unit 100 is via the link 12a arranged tosend a signal to said means 112 representing data for steering angle.

The electronic control unit 100 is operably connected to the means 112 fordetermining if said steering angle has been held within limits indicatingtravelling in a substantially straight forward direction for a certain time periodvia a link 12b. The electronic control unit 100 is via the link 12b arranged toreceive a signal to from said means 112 representing data for steering anglehaving been held within limits indicating travelling in a substantially straightforward direction for a certain time period.

The electronic control unit 100 is operably connected to the means 114 fordetermining if said steering angle has been held within limits indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod via a link 14a. The electronic control unit 100 is via the link 14aarranged to send a signal to said means 114 representing data for steering angle.

The electronic control unit 100 is operably connected to the means 114 fordetermining if said steering angle has been held within limits indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod via a link 14b. The electronic control unit 100 is via the link 14barranged to receive a signal to from said means 114 representing data forsteering angle having been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

The electronic control unit 100 is operably connected to the means 120 fordetermining the steering angle velocity via a link 20. The electronic control unit 100 is via the link 20 arranged to receive a signal from said means 120 representing data for steering angle velocity.

The electronic control unit 100 is operably connected to the means 122 fordetermining if said steering angle velocity has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period via a link 22a. The electronic control unit 100 is via the link 22aarranged to send a signal to said means 122 representing data for steering angle velocity.

The electronic control unit 100 is operably connected to the means 122 fordetermining if said steering angle velocity has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period via a link 22b. The electronic control unit 100 is via the link 22barranged to receive a signal to from said means 122 representing data forsteering angle velocity having been held within limits indicating travelling in a substantially straight forward direction for a certain time period.

The electronic control unit 100 is operably connected to the means 124 fordetermining if said steering angle velocity exceeds a limit indicating intentionto travel in a changing direction, indicating a curve, for a certain time periodvia a link 24a. The electronic control unit 100 is via the link 24a arranged tosend a signal to said means 124 representing data for steering angle velocity.

The electronic control unit 100 is operably connected to the means 124 fordetermining if said steering angle velocity exceeds a limit indicating intentionto travel in a changing direction, indicating a curve, for a certain time periodvia a link 24b. The electronic control unit 100 is via the link 24b arranged toreceive a signal to from said means 124 representing data for steering anglevelocity exceeds a limit indicating intention to travel in a changing direction, indicating a curve, for a certain time period. 31 The electronic control unit 100 is operably connected to the means 126 fordetermining means 126 for determining if said steering angle velocityindicates a, compared to said steering angle velocity indicating a curve,higher steering angle velocity via a link 26a. The electronic control unit 100 isvia the link 26a arranged to send a signal to said means 126 representing data for steering angle velocity.

The electronic control unit 100 is operably connected to the means 126 fordetermining means 126 for determining if said steering angle velocityindicates a, compared to said steering angle velocity indicating a curve,higher steering angle velocity via a link 26b. The electronic control unit 100 isvia the link 26b arranged to receive a signal to from said means 126representing data for steering angle velocity indicating a, compared to saidsteering angle velocity indicating a curve, higher steering angle velocity.

The electronic control unit 100 is operably connected to the means 140 fordetermining the velocity of the vehicle wheels via a link 40. The electroniccontrol unit 100 is via the link 40 arranged to receive a signal from saidmeans 140 representing data for velocity of the vehicle wheels.

The electronic control unit 100 is operably connected to the means 150 forcomparing the velocity of the vehicle wheels via a link 50a. The electroniccontrol unit 100 is via the link 50a arranged to send a signal to said means150 representing data for velocity of the vehicle wheels.

The electronic control unit 100 is operably connected to the means 150 forcomparing the velocity of the vehicle wheels via a link 50b. The electroniccontrol unit 100 is via the link 50b arranged to receive a signal to from saidmeans 150 representing data for comparison of the velocity of the vehicle wheels.

The electronic control unit 100 is operably connected to the means 142 fordetermining if the velocity of all wheels are about the same based on thecomparison of the velocity of the vehicle wheels via a link 42a. The electronic 32 control unit 100 is via the link 42a arranged to send a signal to said means142 representing data for velocity of the vehicle wheels and comparison ofthe velocity of the vehicle wheels.

The electronic control unit 100 is operably connected to the means 142 fordetermining if the velocity of all wheels are about the same based on thecomparison of the velocity of the vehicle wheels via a link 42b. The electroniccontrol unit 100 is via the link 42b arranged to receive a signal to from saidmeans 142 representing data for the velocity of all wheels being about the Same.

The electronic control unit 100 is operably connected to the means 144 fordetermining if the velocity of the vehicle front wheels is determined to differ toa certain extent based on the comparison of the velocity of the vehiclewheels via a link 44a. The electronic control unit 100 is via the link 44aarranged to send a signal to said means 144 representing data for velocity of the vehicle wheels and comparison of the velocity of the vehicle wheels.

The electronic control unit 100 is operably connected to the means 144 fordetermining if the velocity of the vehicle front wheels is determined to differ toa certain extent based on the comparison of the velocity of the vehiclewheels via a link 44b. The electronic control unit 100 is via the link 44barranged to receive a signal to from said means 144 representing data for thevelocity of the vehicle front wheels being determined to differ to a certain eXtent.

The electronic control unit 100 is operably connected to the means 160 fordetermining the extension of the road comprising curvature and topologyalong which the vehicle is travelling via a link 60. The electronic control unit100 is via the link 60 arranged to receive a signal from said means 160representing data for extension of the road comprising curvature and topology along which the vehicle is travelling. 33 The electronic control unit 100 is operably connected to the means 162 fordetecting the trajectory of the road comprising curvature and topology of theroad via a link 62. The electronic control unit 100 is via the link 62 arrangedto receive a signal to from said means 162 representing data for extension ofthe road comprising curvature and topology along which the vehicle is travelling.

The electronic control unit 100 is operably connected to the means 164 fordetermining the current position of the vehicle and extracted map informationof the extension of the road along which the vehicle is travelling via a link 64.The electronic control unit 100 is via the link 64 arranged to receive a signalto from said means 164 representing data for extension of the roadcomprising curvature and topology along which the vehicle is travelling.

The electronic control unit 100 is operably connected to the means 170 fordetermining external conditions comprising weather conditions and/or roadconditions in connection to the vehicle driving along said road via a link 70.The electronic control unit 100 is via the link 70 arranged to receive a signalfrom said means 170 representing data for external conditions comprisingweather conditions and/or road conditions in connection to the vehicle driving along said road.

The electronic control unit 100 is operably connected to the means 172 fordetermining weather conditions in connection to the vehicle driving along saidroad via a link 72. The electronic control unit 100 is via the link 72 arrangedto receive a signal to from said means 172 representing data for weatherconditions in connection to the vehicle driving along said road.

The electronic control unit 100 is operably connected to the means 174 fordetermining road conditions in connection to the vehicle driving along saidroad via a link 74. The electronic control unit 100 is via the link 74 arrangedto receive a signal to from said means 174 representing data for roadconditions in connection to the vehicle driving along said road. 34 The electronic control unit 100 is operably connected to the means 131 forcontrolling the damping of the articulation joint taking the thus determinedsteering angle into account via a link 31. The electronic control unit 100 is viathe link 31 arranged to send a signal to said means 131 representing data forcontrolling the damping of the articulation joint taking the thus determined steering angle into account.

The electronic control unit 100 is operably connected to the means 131a forcontrolling said damping to a relatively higher damping if said steering anglehas been held within limits indicating travelling in a substantially straightforward direction for a certain time period via a link 31a. The electroniccontrol unit 100 is via the link 31a arranged to send a signal to said means131a representing data for controlling the damping to a relatively higherdamping.

The electronic control unit 100 is operably connected to the means 131b forcontrolling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle has been held within limitsindicating intention to travel in a changing direction, indicating a curve, for acertain time period via a link 31b. The electronic control unit 100 is via thelink 31 b arranged to send a signal to said means 131 b representing data forcontrolling the damping to a damping for allowing the vehicle to safely entering into a curve.

The electronic control unit 100 is operably connected to the means 132 forcontrolling the damping of the articulation joint taking the thus determinedsteering angle velocity into account via a link 32. The electronic control unit100 is via the link 32 arranged to send a signal to said means 132representing data for controlling the damping of the articulation joint taking the thus determined steering angle velocity into account.

The electronic control unit 100 is operably connected to the means 132a forcontrolling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantiallystraight forward direction for a certain time period via a link 32a. Theelectronic control unit 100 is via the link 32a arranged to send a signal to saidmeans 132a representing data for controlling the damping to a relatively higher damping.

The electronic control unit 100 is operably connected to the means 132b forcontrolling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle velocity exceeds a limit indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod via a link 32b. The electronic control unit 100 is via the link 32barranged to send a signal to said means 132b representing data forcontrolling the damping to a damping for allowing the vehicle to safely entering into a curve.

The electronic control unit 100 is operably connected to the means 132c forcontrolling said damping to a damping for allowing the vehicle to safely enterinto a turn manoeuvre if said steering angle velocity indicates a, compared tosaid steering angle velocity indicating a curve, higher steering angle velocityvia a link 32c. The electronic control unit 100 is via the link 32c arranged tosend a signal to said means 132c representing data for controlling thedamping to a damping for allowing the vehicle to safely enter into a turn ITIQFIOGUVFG.

The electronic control unit 100 is operably connected to the means 133 forcontrolling the damping of the articulation joint taking the thus determinedvelocity of the vehicle wheels into account via a link 33. The electronic controlunit 100 is via the link 33 arranged to send a signal to said means 133representing data for controlling the damping of the articulation joint taking the thus determined velocity of the vehicle wheels into account.

The electronic control unit 100 is operably connected to the means 133a forcontrolling said damping to a relatively higher damping if the velocity of all 36 wheels are about the same indicating travelling in a substantially straightforward direction for a certain time period via a link 33a. The electroniccontrol unit 100 is via the link 33a arranged to send a signal to said means133a representing data for controlling the damping to a relatively higherdamping.

The electronic control unit 100 is operably connected to the means 133b forcontrolling said damping to a damping for allowing the vehicle to safelyentering into a curve if the velocity of the vehicle front wheels is determinedto differ to a certain extent indicating entering into a curve for a certain timeperiod via a link 33b. The electronic control unit 100 is via the link 33barranged to send a signal to said means 133b representing data forcontrolling the damping to a damping for allowing the vehicle to safely entering into a curve.

The electronic control unit 100 is operably connected to the means 134 forcontrolling the damping of the articulation joint taking the thus determinedextension of the road into account when controlling the damping of thearticulation joint via a link 34. The electronic control unit 100 is via the link 34arranged to send a signal to said means 134 representing data for controllingthe damping of the articulation joint taking the thus determined extension ofthe road into account.

The electronic control unit 100 is operably connected to the means 135 forcontrolling the damping of the articulation joint taking the thus determinedweather conditions into account when controlling the damping of thearticulation joint via a link 35. The electronic control unit 100 is via the link 35arranged to send a signal to said means 135 representing data for controllingthe damping of the articulation joint taking the thus determined weather conditions into account.

The electronic control unit 100 is operably connected to the means 136 forcontrolling the damping of the articulation joint taking the thus determined 37 road conditions into account when controlling the damping of the articulationjoint via a link 36. The electronic control unit 100 is via the link 36 arranged tosend a signal to said means 136 representing data for controlling thedamping of the articulation joint taking the thus determined road conditions into account.

Fig. 4 schematically illustrates a block diagram of a method for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road to an embodiment of the present invention. The vehiclecomprises a first vehicle unit having a steering wheel for steering the vehicle,a second vehicle unit and an articulation joint connecting the first and secondvehicle unit, said first and second vehicle units being pivotable about saidarticulation joint. The articulation is controlled by means of damping members arranged in connection to the articulation joint.

According to the embodiment the method for controlling damping of anarticulation joint of a wheeled articulated vehicle travelling along a roadcomprises a step S1. ln this step the steering angle and/or the steering angle velocity are determined.

According to the embodiment the method for controlling damping of anarticulation joint of a wheeled articulated vehicle travelling along a roadcomprises a step S2. ln this step the damping of the articulation joint iscontrolled taking the thus determined steering angle and/or steering angle velocity into account.

According to the embodiment the method for controlling damping of anarticulation joint of a wheeled articulated vehicle travelling along a roadcomprises a step S3. ln this step.

The step of determining the steering angle comprises according to an embodiment utilizing any suitable steering angle sensor. 38 The step of determining the steering angle velocity comprises according to an embodiment utilizing any suitable steering angle velocity sensor.

The step of controlling the damping of the articulation joint taking the thusdetermined steering angle and/or steering angle velocity into accountcomprises according to an embodiment controlling the damping of thearticulation joint based upon thus determined steering angle and/or steeringangle velocity. The damping of the articulation joint may thus be adaptedbased upon thus determined steering angle and/or steering angle velocity.

The step of controlling the damping of the articulation joint may be obtainedin any suitable way by any suitable means. The step of controlling thedamping of the articulation joint comprises according to an embodimentutilizing an electronic control unit for controlling the damping of the dampingmembers. The damping members comprise according to an embodimenthydraulic cylinders with pistons being movable based upon pressurizedhydraulic fluid, e.g. oil. The damping members comprises valve membersbeing controllable between an open position allowing flow of hydraulic fluidproviding a lower damping and a closed position preventing flow of hydraulicfluid essentially locking the articulation joint and thus providing an essentially stiff damping.

According to an embodiment of the method the step of taking said steeringangle into account comprises the step of controlling said damping to arelatively higher damping if said steering angle has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period, and controlling said damping to a damping for allowing thevehicle to safely entering into a curve if said steering angle has been heldwithin limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period. 39 Thus according to an embodiment the method comprises the step ofdetermining if said steering angle has been held within limits indicatingtravelling in a substantially straight fon/vard direction for a certain time period.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle has been held within limits indicatingintention to travel in a changing direction, indicating a curve, for a certain time penod.

According to an embodiment of the method the step of taking said steeringangle velocity into account comprises the step of controlling said damping toa relatively higher damping if said steering angle velocity has been heldwithin limits indicating travelling in a substantially straight forward direction fora certain time period, controlling said damping to a damping for allowing thevehicle to safely entering into a curve if said steering angle velocity exceedsa limit indicating intention to travel in a changing direction, indicating a curve,for a certain time period, and controlling said damping to a damping forallowing the vehicle to safely enter into a turn manoeuvre if said steeringangle velocity indicates a, compared to said steering angle velocity indicatinga curve, higher steering angle velocity.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle velocity has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period. By controlling said damping to a relatively higher damping if saidsteering angle has been held within limits indicating travelling in asubstantially straight forward direction for a certain time period drivability maybe improved in that a higher damping is obtained independent of the vehiclesspeed and thus even at lower speeds.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle velocity exceeds a limit indicating intentionto travel in a changing direction, indicating a curve, for a certain time period.

Thus according to an embodiment the method comprises the step ofdetermining if said steering angle velocity indicates a, compared to saidsteering angle velocity indicating a curve, higher steering angle velocity.

According to an embodiment the method further comprises the steps of:determining and comparing the velocity of the vehicle wheels; and, if thevelocity of all wheels are about the same taking this as an indication of thevehicle travelling in a straight forward direction, controlling the dampingaccordingly, and, if the velocity of the vehicle front wheels is determined todiffer to a certain extent, taking this as indication of the vehicle entering into acurve and controlling the damping accordingly.

According to this embodiment the method thus comprises the steps of:determining the velocity of the vehicle wheels of the vehicle; and compartingthe thus determined velocity of the vehicle wheels of the vehicle.

According to this embodiment the method thus comprises the step of determining whether all wheels are about the same.

The step of controlling the damping accordingly if it has been indicated thatthe vehicle travelling in a straight forward direction based on the velocity of allwheels being about the same refers to controlling said damping to a relatively higher damping.

According to an embodiment the method further comprises the steps of:determining the extension of the road comprising curvature and topologyalong which the vehicle is travelling; and, taking the thus determinedextension of the road into account when controlling the damping of thearticulation joint.

The step of determining the extension of the road comprising curvature andtopology along which the vehicle is travelling comprises the step of detectingthe trajectory of the road comprising curvature and topology of the road. Thestep of detecting the trajectory of the road comprises utilizing any suitable 41 detector means comprising any suitable detector such as one or morecamera units, one or more laser scanner units, one or more radar units or thelike. The step of detecting slopes may comprise a gyro for detecting the degree of inclination.

The step of determining the extension of the road comprising curvature andtopology along which the vehicle is travelling comprises the step ofdetermining the current position of the vehicle and extracted map informationof the extension of the road along which the vehicle is travelling. The step ofdetermining the current position of the vehicle comprises according to anembodiment utilizing a Global Navigation satellite System, GNSS, e.g. aglobal positioning system, GPS, for continuously determining the position ofthe vehicle and thus whether the vehicle is moving.

By thus determining the extension of the road comprising curvature andtopology along which the vehicle is travelling relevant information foroptimizing control of the damping of the articulation joint is obtained and maybe obtained in time to be able to proactively take action in order to have a damping that will be safe for e.g. an upcoming curve when driving in a slope.

According to an embodiment the method further comprises the steps of:determining external conditions comprising weather conditions and/or roadconditions in connection to the vehicle driving along said road; and taking thethus determined weather conditions and/or road conditions into accountwhen controlling the damping of the articulation joint.

The step of determining the weather conditions comprises determiningweather conditions along the road on which the wheeled articulated vehicle istravelling and in connection to the occasion on which the vehicle is travellingalong said road. The step of determining the weather conditions comprisesaccording to an embodiment utilizing weather sensors comprising anysuitable rain sensor/precipitation sensor e.g. arranged in connection to thewindshield, any suitable temperature sensor, any suitable wind sensor or the 42 like. The step of determining the weather conditions comprises according to an embodiment utilizing external weather data from any externalprovider/server with which the vehicle, i.e. a control unit/server unit or the like of the vehicle, may establish contact.

Thus determined weather conditions may comprise rain and extent of rain,snow and extent of snow, current temperature, wind conditions, extent of wind and direction of wind or the like.

The step of determining the road conditions comprises determining roadconditions along the road on which the wheeled articulated vehicle istravelling and in connection to the occasion on which the vehicle is travellingalong said road. The step of determining the road conditions comprisesaccording to an embodiment utilizing any suitable detector means comprisingany suitable detector unit for detecting the surface of the road along whichthe vehicle is travelling such as one or more camera units and/or one or morelaser scanner units and/or one or more radar units. The step of determiningthe road conditions comprises according to an embodiment utilizing externaldata from any external provider/server with which the vehicle, i.e. a controlunit/server unit or the like of the vehicle, may establish contact.

Thus determined road conditions may comprise slippery road due to e.g. iceon the road, snow on the road, oil on the road, gravel on the road, water onthe road, curves of the road, slopes of the road and/or other road conditionsthat may affect driving along the road.

The method and the method steps described above with reference to fig. 4are according to an embodiment performed with the system l according to fig.3.

With reference to figure 5, a diagram of an apparatus 500 is shown. Thecontrol unit 100 described with reference to fig. 3 may according to anembodiment comprise apparatus 500. Apparatus 500 comprises a non-volatile memory 520, a data processing device 510 and a read/write memory 43 550. 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 seria| communication port, I/O-means, an A/D-converter, a time date entryand transmission unit, an event counter and an interrupt controller (not shown). Non-volatile memory 520 also has a second memory portion 540.

A computer program P is provided comprising routines for controllingdamping of an articulation joint of a wheeled articulated vehicle travellingalong a road according to an embodiment of the present invention. Thevehicle comprises a first vehicle unit having a steering wheel for steering thevehicle, a second vehicle unit and an articulation joint connecting the first andsecond vehicle unit, said first and second vehicle units being pivotable aboutsaid articulation joint. The articulation is controlled by means of dampingmembers arranged in connection to the articulation joint. The program Pcomprises routines for determining the steering angle and/or the steeringangle velocity. The routines for taking said steering angle into accountcomprises routines for controlling said damping to a relatively higher dampingif said steering angle has been held within limits indicating travelling in asubstantially straight forward direction for a certain time period, andcontrolling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle has been held within limitsindicating intention to travel in a changing direction, indicating a curve, for acertain time period. The routines for taking said steering angle velocity intoaccount comprises the step of controlling said damping to a relatively higherdamping if said steering angle velocity has been held within limits indicatingtravelling in a substantially straight forward direction for a certain time period,and controlling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle velocity exceeds a limit indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod, and controlling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre if said steering angle velocity indicates a, 44 compared to said steering angle velocity indicating a curve, higher steeringangle velocity. The program P comprises routines for determining andcomparing the velocity of the vehicle wheels. The program P comprisesroutines for taking the fact that the velocity of all wheels are about the sameas an indication of the vehicle travelling in a straight forward direction andcontrolling the damping accordingly. The program P comprises routines fortaking the fact that the velocity of the vehicle front wheels is determined todiffer to a certain extent as indication of the vehicle entering into a curve andcontrolling the damping accordingly. The program P comprises routines fordetermining the extension of the road comprising curvature and topologyalong which the vehicle is travelling. The program P comprises routines fortaking the thus determined extension of the road into account whencontrolling the damping of the articulation joint. The program P comprisesroutines for determining external conditions comprising weather conditionsand/or road conditions in connection to the vehicle driving along said road.The program P comprises routines for taking the thus determined weatherconditions and/or road conditions into account when controlling the dampingof the articulation joint. The computer program P may be stored in anexecutable manner or in a compressed condition in a separate memory 560 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 516. Non-volatile memory 520 is adaptedfor communication with data processing device 510 via a data bus 513.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 515. To the data 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 determining the steering angle and/or the steeringangle velocity. The signals received on data port 599 can be used byapparatus 500 for The routines for taking said steering angle into accountcomprises routines for controlling said damping to a relatively higher dampingif said steering angle has been held within limits indicating travelling in asubstantially straight forward direction for a certain time period, andcontrolling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle has been held within limitsindicating intention to travel in a changing direction, indicating a curve, for acertain time period. The signals used for taking said steering angle velocityinto account comprises the step of controlling said damping to a relativelyhigher damping if said steering angle velocity has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period, and controlling said damping to a damping for allowing thevehicle to safely entering into a curve if said steering angle velocity exceedsa limit indicating intention to travel in a changing direction, indicating a curve,for a certain time period, and controlling said damping to a damping forallowing the vehicle to safely enter into a turn manoeuvre if said steeringangle velocity indicates a, compared to said steering angle velocity indicatinga curve, higher steering angle velocity. The signals received on data port 599can be used by apparatus 500 for determining and comparing the velocity ofthe vehicle wheels. The signals received on data port 599 can be used byapparatus 500 for taking the fact that the velocity of all wheels are about thesame as an indication of the vehicle travelling in a straight forward direction and controlling the damping accordingly. The signals received on data port 46 599 can be used by apparatus 500 for taking the fact that the velocity of thevehicle front wheels is determined to differ to a certain extent as indication ofthe vehicle entering into a curve and controlling the damping accordingly.The signals received on data port 599 can be used by apparatus 500 fordetermining the extension of the road comprising curvature and topologyalong which the vehicle is travelling. The signals received on data port 599can be used by apparatus 500 for taking the thus determined extension ofthe road into account when controlling the damping of the articulation joint.The signals received on data port 599 can be used by apparatus 500 fordetermining external conditions comprising weather conditions and/or roadconditions in connection to the vehicle driving along said road. The signalsreceived on data port 599 can be used by apparatus 500 for taking the thusdetermined weather conditions and/or road conditions into account whencontrolling the damping of the articulation joint.

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 (17)

47 CLAIIVIS

1. A method for controlling damping of an articulation joint of a wheeledarticulated vehicle (V) travelling along a road (Fi), the vehicle comprising afirst vehicle unit (1) having a steering wheel (SW) for steering the vehicle, asecond vehicle unit (2) and an articulation joint (A) connecting the first andsecond vehicle units (1, 2), said first and second vehicle units being pivotableabout said articulation joint (A), the articulation being controlled by means ofdamping members (D1, D2) arranged in connection to the articulation joint(A) for damping of the same, characterized by the steps of: determining thesteering angle and/or the steering angle velocity; and, controlling thedamping of the articulation joint taking the thus determined steering angle and/or steering angle velocity into account.

2. A method according to claim 1, wherein the step of taking said steeringangle into account comprises the step of controlling said damping to arelatively higher damping if said steering angle has been held within limitsindicating travelling in a substantially straight fon/vard direction for a certaintime period, and controlling said damping to a damping for allowing thevehicle to safely entering into a curve if said steering angle has been heldwithin limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

3. A method according to claim 1 or 2, wherein the step of taking saidsteering angle velocity into account comprises the step of controlling saiddamping to a relatively higher damping if said steering angle velocity hasbeen held within limits indicating travelling in a substantially straight forwarddirection for a certain time period, and controlling said damping to a dampingfor allowing the vehicle to safely entering into a curve if said steering anglevelocity exceeds a limit indicating intention to travel in a changing direction,indicating a curve, for a certain time period, and controlling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre if said 48 steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity.

4. A method according to any of claims 1-3, further comprising the steps of:determining and comparing the velocity of the vehicle wheels; and, if thevelocity of all wheels are about the same taking this as an indication of thevehicle travelling in a straight forward direction, controlling the dampingaccordingly, and, if the velocity of the vehicle front wheels is determined todiffer to a certain extent, taking this as indication of the vehicle entering into acurve and controlling the damping accordingly.

5. A method according to any of claims 1-4, further comprising the steps of:determining the extension of the road comprising curvature and topologyalong which the vehicle is travelling; and, taking the thus determinedextension of the road into account when controlling the damping of thearticulation joint (position and road map/camera)

6. A method according to any of claims 1-5, further comprising the steps of:determining external conditions comprising weather conditions and/or roadconditions in connection to the vehicle driving along said road; and taking thethus determined weather conditions and/or road conditions into account when controlling the damping of the articulation joint.

7. A method according to any one of claims 1-6, wherein said wheeledarticulated vehicle is an articulated bus.

8. A system (l) for controlling damping of an articulation joint of a wheeledarticulated vehicle (V) travelling along a road (Fi), the vehicle comprising afirst vehicle unit (1) having a steering wheel (SW) for steering the vehicle, asecond vehicle unit (2) and an articulation joint (A) connecting the first andsecond vehicle units (1, 2), said first and second vehicle units being pivotableabout said articulation joint (A), the articulation being controlled by means ofdamping members (D1, D2) arranged in connection to the articulation joint(A) for damping of the same, characterized by means (110) for determining 49 the steering angle and/or means (120) for determining the steering anglevelocity; and, means (130), for controlling the damping of the articulation jointtaking the thus determined steering angle (131) and/or steering angle velocity(132) into account.

9. A system according to claim 8, wherein the means (131) for taking saidsteering angle into account comprises means (131a) for controlling saiddamping to a relatively higher damping if said steering angle has been heldwithin limits indicating travelling in a substantially straight forward direction fora certain time period, and means (131b) for controlling said damping to adamping for allowing the vehicle to safely entering into a curve if saidsteering angle has been held within limits indicating intention to travel in achanging direction, indicating a curve, for a certain time period.

10. A system according to claim 8 or 9, wherein the means (132) for takingsaid steering angle velocity into account comprises means (132a) forcontrolling said damping to a relatively higher damping if said steering anglevelocity has been held within limits indicating travelling in a substantiallystraight forward direction for a certain time period, and means (132b) forcontrolling said damping to a damping for allowing the vehicle to safelyentering into a curve if said steering angle velocity exceeds a limit indicatingintention to travel in a changing direction, indicating a curve, for a certain timeperiod, and means (132c) for controlling said damping to a damping forallowing the vehicle to safely enter into a turn manoeuvre if said steeringangle velocity indicates a, compared to said steering angle velocity indicatinga curve, higher steering angle velocity.

11. A system according to any of claims 8-10, further comprising means(140, 150) for determining and comparing the velocity of the vehicle wheels;and means (133a) for taking it as an indication of the vehicle travelling in astraight forward direction if the velocity of all wheels are about the same, thedamping being arranged to be controlled accordingly, and, means (133b) fortaking it as indication of the vehicle entering into a curve and controlling the damping accordingly if the velocity of the vehicle front wheels is determinedto differ to a certain extent.

12. A system according to any of claims 8-11, further comprising means(160) for determining the extension of the road comprising curvature andtopology along which the vehicle is travelling; and, means (134) for taking thethus determined extension of the road into account when controlling thedamping of the articulation joint.

13. A system according to any of claims 8-12, further comprising means(170) for determining external conditions comprising means (172) fordetermining weather conditions and/or means (174) for determining roadconditions in connection to the vehicle driving along said road; and means(135, 136) for taking the thus determined weather conditions and/or roadconditions into account when controlling the damping of the articulation joint.

14. A system according to any one of claims 8-13, wherein said wheeled articulated vehicle is an articulated bus.

15. A vehicle (V) comprising a system (l) according to any of claims 8-14.

16. A computer program (P) for controlling driving of a vehicle along a road,said computer program (P) comprising program code which, when run on anelectronic control unit (100) or another computer (500) connected to theelectronic control unit (100), causes the electronic control unit to perform thesteps according to claim 1-7.

17. A computer program product comprising a digital storage medium storing the computer program according to claim 16.