SE541345C2

SE541345C2 - Method and system for controlling damping of an articulation joint of an articulated vehicle

Info

Publication number: SE541345C2
Application number: SE1650936A
Authority: SE
Inventors: Catharina Sundkvist
Original assignee: Scania Cv Ab
Priority date: 2016-06-29
Filing date: 2016-06-29
Publication date: 2019-07-23
Also published as: SE1650936A1

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 (α) 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

METHOD AND SYSTEM FOR CONTROLLING DAMPING OF AN ARTICULATION JOINT OF AN ARTICULATED VEHICLE TECHNICAL FIELD The invention relates to a method for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road according to the preamble of claim 1. The invention also relates to a system for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road. The invention also relates to a vehicle. The invention in addition relates to a computer program and a computer program product.

BACKGROUND ART So called articulated buses allow a longer legal length than rigid-bodied buses, and thus have a higher passenger capacity. Such articulated buses comprise so called pusher buses having the wheel axle furthest back as the driving axle, with the engine placed in the back as well. This is done to make more room for passengers and a better distribution of them in the bus body. Many challenges come with this type of design as it makes the weight of the vehicle 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 construction leads to high risks of the bus being folded when making a turn with the vehicle or when driving downhill on a slippery slope, especially in combination if making a turn. If the vehicle would get folded it may have to be pulled apart again with external assistance. This construction also leads to general dangerous instability of the whole vehicle since it is hard to manoeuvre. 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 at increased vehicle velocity. The damping is also controlled based upon the angle in the articulation joint and in certain situations the angle velocity of the articulation joint.

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

WO2008073045 discloses damping of the articulation of an articulated vehicle 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 controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road which facilitates improving safety and drivability.

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

SUMMARY OF THE INVENTION These and other objects, apparent from the following description, are achieved by a method, a system, a vehicle, a computer program and a computer program product, as set out in the appended independent claims. Preferred embodiments of the method and the system are defined in appended dependent claims.

Specifically an object of the invention is achieved by a method for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road. The vehicle comprises a first vehicle unit having a steering wheel for steering the vehicle, a second vehicle unit and an articulation joint connecting the first and second vehicle unit, said first and second vehicle units being pivotable about said articulation joint. The articulation is controlled by means of damping members arranged in connection to the articulation joint for damping of the same. The method comprises the steps of: determining the steering angle and/or the steering angle velocity; and, controlling the damping of the articulation joint taking the thus determined steering 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 to an embodiment utilizing any suitable steering angle velocity sensor.

The step of controlling the damping of the articulation joint taking the thus determined steering angle and/or steering angle velocity into account comprises according to an embodiment controlling the damping of the articulation joint based upon thus determined steering angle and/or steering angle velocity. The damping of the articulation joint may thus be adapted based upon thus determined steering angle and/or steering angle velocity.

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

By thus controlling the damping of the articulation joint taking the thus determined steering angle and/or steering angle velocity into account safer driving of the articulated vehicle is facilitated in that proactive damping is obtained since actual turn of the vehicle and possible pivoting effect on the second vehicle unit, i.e. the rear vehicle unit, will be delayed so that adapted damping of the articulation joint has been effected before such pivoting occurs. The articulation angle, i.e. the angle between the first and second vehicle unit, will in a curve be essentially proportional to the steering angle but will appear with a delay compared to the steering angle, wherein proactive damping is facilitated by thus damping the articulation joint in connection to the steering angle indicating a turn. Hereby the damping may be controlled based upon situations where the damping should be higher independent of the vehicle speed, i.e. also at lower speeds, in order to prevent the rear vehicle unit from skidding sideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or creating uncomfortable 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. 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 the intermediate unit of the vehicle, wherein in a relatively higher force of the rear vehicle 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 joint taking the thus determined steering angle and/or steering angle velocity into account manoeuvring of the vehicle may be improved e.g. by controlling the damping such that an increased damping is obtained also at lower speeds when it is determined by the steering angle and/or steering angle velocity that the vehicle is driving in a straight forward direction. Thus by controlling the damping of the articulation joint taking the thus determined steering angle and/or steering angle velocity into account safer driving and improved manoeuvrability of the vehicle is facilitated.

Further, the method the step of taking said steering angle into account comprises the step of controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle to safely entering into a curve if 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 the time period for the delay between a steering wheel action such as a change in steering angle indicating a turn and a corresponding change in the angle of the articulation joint is determined based upon the vehicle velocity and the distance between the steerable front wheels of the vehicle and the articulation joint. The thus determined delay is according to an embodiment used as information for when to adapt the damping of the articulation joint.

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

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

Thus according to an embodiment the method comprises the step of determining if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period. By controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period drivability may be improved in 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 of determining if said steering angle has been held within limits indicating intention to 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 safely entering into a curve if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period proactive adaption of the damping in order to improve safety and drivability is facilitated. Hereby a situation where the rear vehicle unit skids sideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or uncomfortable 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 of the method the step of taking said steering angle velocity into account comprises the step of controlling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, controlling said damping to a damping for allowing the vehicle 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 for allowing the vehicle to safely enter into a turn manoeuvre 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 method comprises the step of determining if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period. By controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period drivability may be improved in that a higher damping is obtained independent of the vehicles speed and thus even at lower speeds.

Thus according to an embodiment the method comprises the step of determining if said steering angle velocity exceeds a limit indicating intention to 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 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 proactive adaption of the damping in order to improve safety and drivability is facilitated. Hereby a situation where the rear vehicle unit skids sideways in an undesired and unsafe manner, e.g. creating a so called jackknife situation and/or uncomfortable 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.

Thus according to an embodiment the method comprises the step of determining if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity. By controlling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity proactive adaption of the damping in order to improve safety and drivability is facilitated. Hereby a situation where the rear vehicle unit skids sideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or uncomfortable 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 and comparing the velocity of the vehicle wheels; and, if the velocity of all wheels are about the same taking this as an indication of the vehicle travelling in a straight forward direction, controlling the damping accordingly, and, if the velocity of the vehicle front wheels is determined to differ to a certain extent, taking this as indication of the vehicle entering into a curve 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 of determining whether all wheels are about the same.

The step of controlling the damping accordingly if it has been indicated that the vehicle travelling in a straight forward direction based on the velocity of all wheels 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 topology along 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 and topology along which the vehicle is travelling comprises the step of detecting the trajectory of the road comprising curvature and topology of the road. The step of detecting the trajectory of the road comprises utilizing any suitable detector means comprising any suitable detector such as one or more camera units, one or more laser scanner units, one or more radar units or the like. 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 and topology along which the vehicle is travelling comprises the step of determining the current position of the vehicle and extracted map information of the extension of the road along which the vehicle is travelling. The step of determining the current position of the vehicle comprises according to an embodiment utilizing a Global Navigation 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.

By thus determining the extension of the road comprising curvature and topology along which the vehicle is travelling relevant information for optimizing control of the damping of the articulation joint is obtained and may be 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. By taking the thus determined extension of the road into account when controlling the damping of the articulation joint proactive adaption of the damping in order to improve safety and drivability is facilitated. Hereby a situation where the rear vehicle unit skids sideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or uncomfortable 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 road conditions in connection to the vehicle driving along said road; and taking the thus determined weather conditions and/or road conditions into account when controlling the damping of the articulation joint.

The step of determining the weather conditions comprises determining weather conditions along the road on which the wheeled articulated vehicle is travelling and in connection to the occasion on which the vehicle is travelling along said road. The step of determining the weather conditions comprises according to an embodiment utilizing weather sensors comprising any suitable rain sensor/precipitation sensor e.g. arranged in connection to the windshield, any suitable temperature sensor, any suitable wind sensor or the like. The step of determining the weather conditions comprises according to an embodiment utilizing external weather data 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 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 when controlling the damping of the articulation joint proactive adaption of the damping in order to improve safety and drivability is facilitated.

The step of determining the road conditions comprises determining road conditions along the road on which the wheeled articulated vehicle is travelling and in connection to the occasion on which the vehicle is travelling along said road. The step of determining the road conditions comprises according to an embodiment utilizing any suitable detector means comprising any suitable detector unit for detecting the surface of 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 step of determining the road conditions comprises according to an embodiment utilizing external data 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. ice on the road, snow on the road, oil on the road, gravel on the road, water on the road, curves of the road, slopes of the road and/or other road conditions that may affect driving along the road.

By thus taking the determined road conditions into account when controlling the damping of the articulation joint proactive adaption of the damping in order to improve safety and drivability is facilitated. Hereby a situation where the rear vehicle unit skids sideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or uncomfortable 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.

By thus taking the determined weather conditions and road conditions into account when controlling the damping of the articulation joint proactive adaption of the damping in order to improve safety and drivability is facilitated. Hereby a situation where the rear vehicle unit skids sideways in an undesired and unsafe manner, e.g. creating a so called jack-knife situation and/or uncomfortable 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 of the method said wheeled articulated vehicle is an articulated bus. According to an embodiment the articulated bus is a so called accordion bus. According to an embodiment of the method said wheeled articulated vehicle is an articulated passenger vehicle. According to an 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 the rear vehicle unit, and a third vehicle unit being an intermediate vehicle unit, wherein a first articulation joint connects the front and intermediate vehicle units which are pivotable about said first articulation joint, and a second articulation joint connects the intermediate and rear vehicle units which are pivotable about said second articulation joint. The articulation for the bi-articulated bus is arranged to be controlled by means of damping members arranged 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 wheeled articulated vehicle travelling along a road. The vehicle comprises a first vehicle unit having a steering wheel for steering the vehicle, a second vehicle unit and an articulation joint connecting the first and second vehicle unit, said first and second vehicle units being pivotable about said articulation joint. The articulation is arranged to be controlled by means of damping members arranged in connection to the articulation joint for damping of the same. The system comprises means for determining the steering angle and/or means for determining the steering angle velocity; and, means for controlling the damping 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 relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and means for controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle has been 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 for determining if 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 the means for taking said steering angle velocity into account comprises means for controlling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and means for controlling said damping to a damping for allowing the vehicle 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 means for controlling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre 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 for determining if said steering angle velocity has been 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 for determining if said steering angle velocity exceeds a limit 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 for determining if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity. By controlling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre 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 further comprises means for determining and comparing the velocity of the vehicle wheels; and means for taking it as an indication of the vehicle travelling in a straight forward direction if the velocity of all wheels are about the same, the damping being arranged to be controlled accordingly, and, means for taking it as indication of the vehicle entering into a curve and controlling the damping accordingly if the velocity of the vehicle front wheels is determined to differ to a certain extent.

According to an embodiment the system further comprises means for determining the extension of the road comprising curvature and topology along which the vehicle is travelling; and, means for taking the thus determined extension of the road into account when controlling the damping of the articulation joint.

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

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

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

The system for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road is adapted to perform the methods as set out herein.

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

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

Specifically an object of the invention is achieved by a computer program for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road, said computer program comprising program code which, when run on an electronic control unit or another computer connected to the electronic control unit, causes the electronic control unit to perform methods as set out herein.

Specifically an object of the invention is achieved by a computer program product comprising a digital storage medium storing the computer program.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention reference is made to the following detailed description when read in conjunction with the accompanying drawings, wherein like reference characters refer to like parts throughout the several views, and in which: Fig. 1a schematically illustrates a side view of a wheeled articulated vehicle having a front and rear vehicle unit according to the present invention; Fig. 1b schematically illustrates a plan view of the articulated vehicle in fig. 1a; Fig. 1c schematically illustrates a plan view of the articulated vehicle in fig. 1b where the rear vehicle unit has pivoted about an articulation joint relative to the front vehicle unit; Fig. 1d schematically illustrates a side view of the articulated vehicle in fig. 1 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; Fig. 3 schematically illustrates a block diagram of a system for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road according to an embodiment of the present invention; Fig. 4 schematically illustrates a block diagram of a method for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along 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 a physical connector, such as an optoelectronic communication wire, or a nonphysical connector such as a wireless connection, for example a radio or microwave link.

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 vehicle according to the present invention. The exemplified vehicle V is an articulated bus in the shape of an accordion bus. The vehicle comprises a system I for controlling damping of an articulation joint of the wheeled articulated vehicle V travelling along a road R according to an embodiment of the present invention.

The vehicle V comprises a first vehicle unit 1 having a steering wheel SW for steering the vehicle and a second vehicle unit 2. The vehicle V has an intermediate unit 3 between the first and second vehicle units 1, 2. The intermediate unit 3 comprises an articulation joint A schematically illustrated in 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 front wheel WL1 is shown, and a set of intermediate wheels of which the left intermediate wheel WL3 is shown. The second vehicle unit 2 has a set of rear 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 driving the 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.

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 the second vehicle unit 2. The powered rear wheeled axel X2 is also called the drive axle X2. The drive axle X2 is supporting said set of left and right rear wheels W2L, W2R. The vehicle V has an intermediate wheeled axel X3 arranged in the first vehicle unit 1. The intermediate axle X3 is supporting said set of left and right intermediate wheels W3L, W3R.

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

The steering wheel SW is connected to the front wheels W1L, W1R and configured to steer the front wheels W1L, W1R by turning the steering wheel changing the steering wheel angle. By changing the steering wheel angle a corresponding change in the front wheels W1L, W1R will be generated.

In fig. 1 b the front wheels W1L, W1R have been turned by means of changing the steering angle to a steering angle ?.

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 A relative to the first vehicle unit 1 such that an articulation angle ? is formed.

By looking at the present steering wheel angle ? and what the that angle has been for some time it can be determined whether the vehicle is said to travel in a straight line and being in a straight position or not. If the steering angle has been the same for a certain time the vehicle can be defined as travelling in a straight forward direction. Also, by looking at the angle velocity a complementary indication of the movement of the vehicle can be made, e.g. if higher than zero an upcoming turn can be suspected. Additionally, data such as wheel speed can also help confirming the positioning of the vehicle. If all wheels have the same speed the vehicle is with a high probability travelling in a straight line. If the speed of one of the front wheels is suddenly reduced the vehicle can be said to start going into a curve.

If the vehicle speed is known and the steering angle is known it can also be known when articulation will need to have a certain curvature / angle to be in line with the road. If it is known when the articulation will have a certain angle the damping can be ramped up ahead of time, i.e. proactively, and increase stability of the vehicle. This may according to an embodiment be determined with the equation below.

Image available on "Original document" A Global Navigation Satellite System, GNSS, e.g. a global positioning system, GPS, for continuously determining the position of the vehicle is according to an embodiment applied to complement this algorithm with 2D or 3D map data. When the vehicle is known to travel in a forwards direction on a straight road a much higher damping can be applied, and more stability for the vehicle as a whole is achieved.

If damping is increased sooner or later than the actual need, the driver will not achieve the curvature of the vehicle that needed to drive the full curve. It is dangerous to stiffen the articulation at the wrong time; exact timing for the amount of damping for when going into, during and going out of a curve, is crucial. E.g. when the vehicle is turning the articulation cannot be totally stiffened, the joint must be able to move. If the road is known to be straight or the 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 the steering wheel angle a illustrated in fig. 1b with the front wheels turned to an angle change to an angle ? in the articulation joint A illustrated in fig. 1c as a consequence 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 ?.

Thus according to the invention the damping of the articulation joint A is controlled taking the thus determined steering angle and/or steering angle velocity into account. In the example in fig. 1d also the slope and the road condition is taken into account.

By proactive increased damping according to the present invention in the articulation joint A in hilly topology as in fig. 1d prevention of the vehicle bending /get critical articulation angles and end up in safety critical situations is obtained. Hereby a more progressive, enhanced and proactive damping strategy can be applied for low speeds and low angles (and low angle speeds) 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, D2 arranged in connection to the articulation joint. Controlling the damping of the articulation joint A comprises according to an embodiment utilizing an electronic control unit ECU for controlling the damping of the damping members D1, D2.

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

The damping members D1, D2 comprise according to an embodiment hydraulic cylinders C1, C2 with pistons P1, P2 being movable based upon hydraulic fluid, e.g. oil. The damping members D1, D2 comprise valve members V1, V2 being controllable between an open position allowing flow of hydraulic fluid via a fluid line F1, F2 providing a lower damping and a closed 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 this embodiment utilizing an electronic control unit ECU for controlling the damping of the damping members D1, D2. The electronic control unit is operably connected to the respective valve V1, V2 for receiving information about 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 M being rotatably journalled in said intermediate unit 3.

The cylinder C1, C2 are connected to the second vehicle unit at one end and to the rotatable member M at the opposite end via the pistons P1, P2 so as to allow 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 I for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road according to an embodiment of the present invention.

The vehicle comprises a first vehicle unit having a steering wheel for steering the vehicle, a second vehicle unit and an articulation joint connecting the first and second vehicle unit, said first and second vehicle units being pivotable about said articulation joint. The articulation is controlled by means of damping members arranged in connection to the articulation joint.

The system I comprises an electronic control unit 100.

The system I comprises means 110 for determining the steering angle. The means 110 for determining the steering angle comprises any suitable steering angle sensor.

According to an embodiment the means 110 for determining the steering angle comprises means 112 for determining if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period.

According to an embodiment the means 110 for determining the steering angle comprises means 114 for determining if said steering angle has been held 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 angle velocity. The means 120 for determining the steering angle velocity comprises any suitable steering angle velocity sensor. According to an embodiment means 120 for determining the steering angle velocity comprises any suitable steering angle sensor, wherein the steering angle velocity is arranged to be determined by continuously or intermittently determining the steering angle with said steering angle sensor.

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

According to an embodiment the means 120 for determining the steering angle velocity comprises means 124 for determining if said steering angle velocity 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 steering angle velocity comprises means 126 for determining if said steering angle 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 the articulation joint.

The means 130 for controlling the damping of the articulation joint comprises means 131 for controlling the damping of the articulation joint taking the thus determined steering angle into account.

The means 130 for controlling the damping of the articulation joint comprises means 132 for controlling the damping of the articulation joint taking the thus determined steering angle velocity into account.

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

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

According to an embodiment of the system I the means 131 for taking said steering angle into account comprises means 131b for controlling said damping to a damping for allowing the vehicle to safely entering into a curve if 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 said steering angle velocity into account comprises means 132a for controlling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period.

According to an embodiment of the system I the means 132 for taking said steering angle velocity into account comprises means 132b for controlling said damping to a damping for allowing the vehicle 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. The means 132b for controlling said damping to a relatively higher damping is according to an embodiment arranged to control said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in an evenly distributed curve, distributed so that the articulation can have the same angle for a certain time period.

According to an embodiment of the system I the means 132 for taking said steering angle velocity into account comprises means 132c for controlling said damping to a damping for allowing the vehicle to safely enter into a turn manoeuvre 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 for determining the velocity of the vehicle wheels. The means 140 for determining 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 for comparing the velocity of the vehicle wheels. The means 150 for comparing the velocity of the vehicle wheels may comprise any suitable unit for comparing data from the means 140. The means 150 for comparing the velocity of the vehicle wheels is according to an embodiment comprised in the electronic control unit.

The means 130 for controlling the damping of the articulation joint comprises means 133 for controlling 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 comprises means 142 for determining if the velocity of all wheels are about the same based on the comparison of the velocity of the vehicle wheels.

The means 140 for determining the velocity of the vehicle wheels comprises means 144 for determining if the velocity of the vehicle front wheels is determined to differ to a certain extent based on the comparison of the velocity of the vehicle wheels.

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

According to an embodiment of the system I the means 133 for taking said determined velocity of the vehicle wheels into account comprises means 133b for controlling said damping to a damping for allowing the vehicle to safely entering into a curve if the velocity of the vehicle front wheels is determined 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 determined velocity of the vehicle wheels into account is arranged to control the damping to a relatively higher damping if the vehicle is in a curve having an extension such 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 for determining the extension of the road comprising curvature and topology along which the vehicle is travelling.

The means 160 for determining the extension of the road comprising curvature and topology along which the vehicle is travelling comprises means 162 for detecting the trajectory of the road comprising curvature and topology of the road. The means 162 for detecting the trajectory of the road comprises any suitable detector means comprising any suitable detector such as one or more camera units, one or more laser scanner units, one or more radar units or 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 comprising curvature and topology along which the vehicle is travelling comprises means 164 for determining the current position of the vehicle and extracted map information of the extension of the road along which the vehicle is travelling.

The means 164 for determining the current position of the vehicle and extracted map information of the extension of the road along which the vehicle is travelling comprises according to an embodiment a map information unit 164a comprising map data comprising information about the trajectory 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 and extracted map information of the extension of the road along which the vehicle is travelling comprises means 164b for determining the current position of the vehicle. The means 164b for determining the current position of the vehicle comprises according to an embodiment utilizing a Global Navigation 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 comprises means 134 for controlling the damping of the articulation joint taking the thus determined extension of the road into account when controlling the damping of the articulation joint.

According to an embodiment the system I further comprises means 170 for determining external conditions comprising weather conditions and/or road conditions in connection to the vehicle driving along said road.

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

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

The means 172 for determining weather conditions in connection to the vehicle driving along said road comprises one or more weather sensor units. The weather sensor units may comprise one or more rain sensor units. The weather 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 the vehicle driving along said road comprises according to an embodiment means for extracting external weather data from one or more external weather data units comprising any suitable external server unit. The means 172 for determining weather conditions in connection to the vehicle driving along 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 for determining road conditions in connection to the vehicle driving along said road.

The means 174 for determining road conditions in connection to the vehicle driving along said road comprises means for detecting road conditions in connection to the vehicle driving along said road. The means for detecting road conditions comprises any suitable detector unit for detecting the surface of 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 vehicle driving along said road comprises means for extracting information about road conditions from one or more external units comprising any suitable server unit.

Thus determined road conditions may comprise slippery road due to e.g. ice on the road, snow on the road, oil on the road, gravel on the road, water on the 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 comprises means 135 for controlling the damping of the articulation joint taking the thus determined weather conditions into account when controlling the damping of the articulation joint.

The means 130 for controlling the damping of the articulation joint comprises means 136 for controlling the damping of the articulation joint taking the thus determined road conditions into account when controlling the damping of the articulation joint.

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

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 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 for determining if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period via a link 12a. The electronic control unit 100 is via the link 12a arranged to send a signal to said means 112 representing data for steering angle.

The electronic control unit 100 is operably connected to the means 112 for determining if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period via a link 12b. The electronic control unit 100 is via the link 12b arranged to receive a signal to from said means 112 representing data for steering angle 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 114 for determining if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period via a link 14a. The electronic control unit 100 is via the link 14a arranged 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 for determining if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period via a link 14b. The electronic control unit 100 is via the link 14b arranged to receive a signal to from said means 114 representing data for steering 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 for determining 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 for determining if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period via a link 22a. The electronic control unit 100 is via the link 22a arranged 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 for determining if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period via a link 22b. The electronic control unit 100 is via the link 22b arranged to receive a signal to from said means 122 representing data for steering 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 for determining if said steering angle velocity exceeds a limit indicating intention to travel in a changing direction, indicating a curve, for a certain time period via a link 24a. The electronic control unit 100 is via the link 24a arranged to send a signal to said means 124 representing data for steering angle velocity.

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

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

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

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

The electronic control unit 100 is operably connected to the means 142 for determining if the velocity of all wheels are about the same based on the comparison of the velocity of the vehicle wheels via a link 42a. The electronic control unit 100 is via the link 42a arranged to send a signal to said means 142 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 142 for determining if the velocity of all wheels are about the same based on the comparison of the velocity of the vehicle wheels via a link 42b. The electronic control unit 100 is via the link 42b arranged to receive a signal to from said means 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 for determining if the velocity of the vehicle front wheels is determined to differ to a certain extent based on the comparison of the velocity of the vehicle wheels via a link 44a. The electronic control unit 100 is via the link 44a arranged 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 for determining if the velocity of the vehicle front wheels is determined to differ to a certain extent based on the comparison of the velocity of the vehicle wheels via a link 44b. The electronic control unit 100 is via the link 44b arranged to receive a signal to from said means 144 representing data for the velocity 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 for determining the extension of the road comprising curvature and topology along which the vehicle is travelling via a link 60. The electronic control unit 100 is via the link 60 arranged to receive a signal from said means 160 representing data for extension of the road comprising curvature and topology along which the vehicle is travelling.

The electronic control unit 100 is operably connected to the means 162 for detecting the trajectory of the road comprising curvature and topology of the road via a link 62. The electronic control unit 100 is via the link 62 arranged to receive a signal to from said means 162 representing data for extension of the road comprising curvature and topology along which the vehicle is travelling.

The electronic control unit 100 is operably connected to the means 164 for determining the current position of the vehicle and extracted map information of 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 signal to from said means 164 representing data for extension of the road comprising curvature and topology along which the vehicle is travelling.

The electronic control unit 100 is operably connected to the means 170 for determining external conditions comprising weather conditions and/or road conditions 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 signal from said means 170 representing data for external conditions comprising weather 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 for determining weather conditions in connection to the vehicle driving along said road via a link 72. The electronic control unit 100 is via the link 72 arranged to receive a signal to from said means 172 representing data for weather conditions in connection to the vehicle driving along said road.

The electronic control unit 100 is operably connected to the means 174 for determining road conditions in connection to the vehicle driving along said road via a link 74. The electronic control unit 100 is via the link 74 arranged to receive a signal to from said means 174 representing data for road conditions in connection to the vehicle driving along said road.

The electronic control unit 100 is operably connected to the means 131 for controlling the damping of the articulation joint taking the thus determined steering angle into account via a link 31. The electronic control unit 100 is via the link 31 arranged to send a signal to said means 131 representing data for controlling 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 for controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period via a link 31a. The electronic control unit 100 is via the link 31a arranged to send a signal to said means 131a representing data for controlling the damping to a relatively higher damping.

The electronic control unit 100 is operably connected to the means 131b for controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period via a link 31 b. The electronic control unit 100 is via the link 31b arranged to send a signal to said means 131b representing data for controlling 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 for controlling the damping of the articulation joint taking the thus determined steering angle velocity into account via a link 32. The electronic control unit 100 is via the link 32 arranged to send a signal to said means 132 representing 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 for controlling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period via a link 32a. The electronic control unit 100 is via the link 32a arranged to send a signal to said means 132a representing data for controlling the damping to a relatively higher damping.

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

The electronic control unit 100 is operably connected to the means 133 for controlling the damping of the articulation joint taking the thus determined velocity of the vehicle wheels into account via a link 33. The electronic control unit 100 is via the link 33 arranged to send a signal to said means 133 representing 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 for controlling said damping to a relatively higher damping if the velocity of all wheels are about the same indicating travelling in a substantially straight forward direction for a certain time period via a link 33a. The electronic control unit 100 is via the link 33a arranged to send a signal to said means 133a representing data for controlling the damping to a relatively higher damping.

The electronic control unit 100 is operably connected to the means 133b for controlling said damping to a damping for allowing the vehicle to safely entering into a curve if the velocity of the vehicle front wheels is determined to differ to a certain extent indicating entering into a curve for a certain time period via a link 33b. The electronic control unit 100 is via the link 33b arranged to send a signal to said means 133b representing data for controlling 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 for controlling the damping of the articulation joint taking the thus determined extension of the road into account when controlling the damping of the articulation joint via a link 34. The electronic control unit 100 is via the link 34 arranged to send a signal to said means 134 representing data for controlling the damping of the articulation joint taking the thus determined extension of the road into account.

The electronic control unit 100 is operably connected to the means 135 for controlling the damping of the articulation joint taking the thus determined weather conditions into account when controlling the damping of the articulation joint via a link 35. The electronic control unit 100 is via the link 35 arranged to send a signal to said means 135 representing data for controlling the 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 for controlling the damping of the articulation joint taking the thus determined road conditions into account when controlling the damping of the articulation joint via a link 36. The electronic control unit 100 is via the link 36 arranged to send a signal to said means 136 representing data for controlling the damping of the articulation joint taking the thus determined road conditions into account.

Fig. 4 schematically illustrates a block diagram of a method for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road to an embodiment of the present invention. The vehicle comprises a first vehicle unit having a steering wheel for steering the vehicle, a second vehicle unit and an articulation joint connecting the first and second vehicle unit, said first and second vehicle units being pivotable about said articulation 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 an articulation joint of a wheeled articulated vehicle travelling along a road comprises a step S1. In this step the steering angle and/or the steering angle velocity are determined.

According to the embodiment the method for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road comprises a step S2. In this step the damping of the articulation joint is controlled taking the thus determined steering angle and/or steering angle velocity into account.

According to the embodiment the method for controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road comprises a step S3. In this step.

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

According to an embodiment of the method the step of taking said steering angle into account comprises the step of controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle has been 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 method comprises the step of determining if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period.

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

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

By thus determining the extension of the road comprising curvature and topology along which the vehicle is travelling relevant information for optimizing control of the damping of the articulation joint is obtained and may be 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.

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

With reference to figure 5, a diagram of an apparatus 500 is shown. The control unit 100 described with reference to fig. 3 may according to an embodiment comprise apparatus 500. Apparatus 500 comprises a non-volatile memory 520, a data processing device 510 and a read/write memory 550. Non-volatile memory 520 has a first memory portion 530 wherein a computer program, such as an operating system, is stored for controlling the function of apparatus 500. Further, apparatus 500 comprises a bus controller, a serial communication port, l/O-means, an A/D-converter, a time date entry and 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 controlling damping of an articulation joint of a wheeled articulated vehicle travelling along a road according to an embodiment of the present invention. The vehicle comprises a first vehicle unit having a steering wheel for steering the vehicle, a second vehicle unit and an articulation joint connecting the first and second vehicle unit, said first and second vehicle units being pivotable about said articulation joint. The articulation is controlled by means of damping members arranged in connection to the articulation joint. The program P comprises routines for determining the steering angle and/or the steering angle velocity. The routines for taking said steering angle into account comprises routines for controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period. The routines for taking said steering angle velocity into account comprises the step of controlling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle 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 for allowing the vehicle to safely enter into a turn manoeuvre if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity. The program P comprises routines for determining and comparing the velocity of the vehicle wheels. The program P comprises routines for taking the fact that the velocity of all wheels are about the same as an indication of the vehicle travelling in a straight forward direction and controlling the damping accordingly. The program P comprises routines for taking the fact that the velocity of the vehicle front wheels is determined to differ to a certain extent as indication of the vehicle entering into a curve and controlling the damping accordingly. The program P comprises routines for determining the extension of the road comprising curvature and topology along which the vehicle is travelling. The program P comprises routines for taking the thus determined extension of the road into account when controlling the damping of the articulation joint. The program P comprises routines for determining external conditions comprising weather conditions and/or road conditions in connection to the vehicle driving along said road. The program P comprises routines for taking the thus determined weather conditions and/or road conditions into account when controlling the damping of the articulation joint. The computer program P may be stored in an executable 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 function it should be understood that data processing device 510 performs a certain part of the program which is stored in separate memory 560, or a certain part of the program which is stored in read/write memory 550.

Data processing device 510 may communicate with a data communications port 599 by means of a data bus 516. Non-volatile memory 520 is adapted for communication with data processing device 510 via a data bus 513. Separate memory 560 is adapted for communication with data processing device 510 via a data bus 511. Read/write memory 550 is adapted for communication with data processing device 510 via a data bus 515. To the data communications port 599 e.g. the links connected to the control units 100 may be connected.

When data is received on data port 599 it is temporarily stored in second memory portion 540. When the received input data has been temporarily stored, data processing device 510 is set up to perform execution of code in a manner described above. The signals received on data port 599 can be used by apparatus 500 for determining the steering angle and/or the steering angle velocity. The signals received on data port 599 can be used by apparatus 500 for The routines for taking said steering angle into account comprises routines for controlling said damping to a relatively higher damping if said steering angle has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period. The signals used for taking said steering angle velocity into account comprises the step of controlling said damping to a relatively higher damping if said steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle 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 for allowing the vehicle to safely enter into a turn manoeuvre if said steering angle velocity indicates a, compared to said steering angle velocity indicating a curve, higher steering angle velocity. The signals received on data port 599 can be used by apparatus 500 for determining and comparing the velocity of the vehicle wheels. The signals received on data port 599 can be used by apparatus 500 for taking the fact that the velocity of all wheels are about the same as an indication of the vehicle travelling in a straight forward direction and controlling the damping accordingly. The signals received on data port 599 can be used by apparatus 500 for taking the fact that the velocity of the vehicle front wheels is determined to differ to a certain extent as indication of the vehicle entering into a curve and controlling the damping accordingly. The signals received on data port 599 can be used by apparatus 500 for determining the extension of the road comprising curvature and topology along which the vehicle is travelling. The signals received on data port 599 can be used by apparatus 500 for taking the thus determined extension of the road into account when controlling the damping of the articulation joint. The signals received on data port 599 can be used by apparatus 500 for determining external conditions comprising weather conditions and/or road conditions in connection to the vehicle driving along said road. The signals received on data port 599 can be used by apparatus 500 for taking the thus determined weather conditions and/or road conditions into account when controlling the damping of the articulation joint.

Parts of the methods described herein can be performed by apparatus 500 by means of data processing device 510 running the program stored in separate memory 560 or read/write memory 550. When apparatus 500 runs the program, parts of the methods described herein are executed.

The foregoing description of the preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated.

Claims

1. 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, characterized by the steps of: determining the steering angle and/or the steering angle velocity; and, controlling the damping of the articulation joint taking the thus determined steering angle and/or steering angle velocity into account, wherein the step of taking said steering angle and/or steering angle velocity into account comprises the step of controlling said damping to a relatively higher damping if said steering angle and/or steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle and/or steering angle velocity has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period.

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

3. A method according to any of claims 1-2, further comprising the steps of: determining the extension of the road comprising curvature and topology along which the vehicle is travelling; and, taking the thus determined extension of the road into account when controlling the damping of the articulation joint (position and road map/camera)

4. A method according to any of claims 1-3, further comprising the steps of: determining external conditions comprising weather conditions and/or road conditions in connection to the vehicle driving along said road; and taking the thus determined weather conditions and/or road conditions into account when controlling the damping of the articulation joint.

5. A method according to any one of claims 1-4, wherein said wheeled articulated vehicle is an articulated bus.

6. A system (I) 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, characterized by means (110) for determining the steering angle and/or means (120) for determining the steering angle velocity; and, means (130), for controlling the damping of the articulation joint taking the thus determined steering angle (131) and/or steering angle velocity (132) into account wherein the means (131, 132) for taking said steering angle and/or steering angle velocity into account comprises means (131a, 132b) for controlling said damping to a relatively higher damping if said steering angle and/or steering angle velocity has been held within limits indicating travelling in a substantially straight forward direction for a certain time period, and means (131b, 132c) for controlling said damping to a damping for allowing the vehicle to safely entering into a curve if said steering angle has been held within limits indicating intention to travel in a changing direction, indicating a curve, for a certain time period..

7. A system according to any of claim 6, 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 a straight forward direction if the velocity of all wheels are about the same, the damping being arranged to be controlled accordingly, and, means (133b) for taking it as indication of the vehicle entering into a curve and controlling the damping accordingly if the velocity of the vehicle front wheels is determined to differ to a certain extent.

8. A system according to any of claims 6-7, further comprising means (160) for determining the extension of the road comprising curvature and topology along which the vehicle is travelling; and, means (134) for taking the thus determined extension of the road into account when controlling the damping of the articulation joint.

9. A system according to any of claims 6-8, further comprising means (170) for determining external conditions comprising means (172) for determining weather conditions and/or means (174) for determining road conditions in connection to the vehicle driving along said road; and means (135, 136) for taking the thus determined weather conditions and/or road conditions into account when controlling the damping of the articulation joint.

10. A system according to any one of claims 6-9, wherein said wheeled articulated vehicle is an articulated bus.

11. A vehicle (V) comprising a system (I) according to any of claims 6-10.

12. A computer program (P) for controlling driving of a vehicle along a road, said computer program (P) comprising program code which, when run on an electronic control unit (100) or another computer (500) connected to the electronic control unit (100), causes the electronic control unit to perform the steps according to claim 1-5.

13. A computer program product comprising a digital storage medium storing the computer program according to claim 12.