SE540380C2

SE540380C2 - A method and a system for controlling an articulated vehicle

Info

Publication number: SE540380C2
Application number: SE1651648A
Authority: SE
Inventors: Sandberg Jesper; Claesson André
Original assignee: Scania Cv Ab
Priority date: 2016-12-15
Filing date: 2016-12-15
Publication date: 2018-09-04
Also published as: DE102017011298A1; SE1651648A1

Abstract

The invention relates to a method for controlling an articulated vehicle (1), the articulated vehicle (1) comprising: a front vehicle section (4) and a rear vehicle section (6); an articulation unit (8) allowing the front vehicle section (4) and the rear vehicle section (6) to pivot in relation to each other; and a damping arrangement (50) arranged to control the pivotal movement about the articulation unit (8); the method comprising the steps of: identifying (s101) an intention to turn the vehicle (1); determining (s102) if any external object (110, 110a, 110b) would cause a dangerous situation if the intended turning of the vehicle (1) is realised; and if so controlling (s103) the damping arrangement (50), such that pivotal movement about the articulation unit (8) is impeded.

Description

A method and a system for controlling an articulated vehicle TECHNICAL FIELD The present invention relates to a method for controlling an articulated vehicle, a system for controlling an articulated vehicle, a vehicle comprising such a system, a computer program and a computer-readable medium.

BACKGROUND Articulated vehicles, such as buses, articulated lorries and trailer trucks, comprise an articulation unit connecting a front vehicle section with a rear vehicle section and enabling the two vehicle sections to pivot in relation to each other. One example of articulated buses is the so called pusher bus, which has a rear driving axle and the propulsion unit arranged at the rear vehicle section. Many challenges come with this type of design as it makes the weight of the vehicle uneven with a great amount of weight in the rear vehicle section on the driving axle, leaving the middle axle with less weight, pressure and grip. This construction may lead to a risk of the bus being folded when making a turn with the vehicle or when driving downhill on a slippery slope. This construction may also lead to general instability of the whole vehicle.

Various ways of controlling articulated vehicles are today known for reducing the risk for dangerous situations. To prevent an articulated vehicle from being folded and to ensure that the vehicle is stable, a damping arrangement may for example be arranged in association with the articulation unit. The damping provided by the damping arrangement may be controlled based on steering angle, articulation angle, articulation angle rate, vehicle speed and similar parameters. Document SE538200 C2 discloses a method for controlling an articulated vehicle changing travel direction, where, if it is determined that the change of travel direction will cause the vehicle to collide with an object in the surroundings, wheels of a rear axle are steered to avoid the collision risk.

SUMMARY OF THE INVENTION Despite known solutions in the field, there is still a need to develop a method for controlling an articulated vehicle for safety reasons.

An object of the present invention is therefore to achieve a new and advantageous method for controlling an articulated vehicle, which reduces the risk of dangerous situations associated with turning the vehicle.

Another object of the present invention is to achieve a new and advantageous system for controlling an articulated vehicle, which reduces the risk of dangerous situations associated with turning the vehicle.

The herein mentioned objects are achieved by a method for controlling an articulated vehicle, a system for controlling an articulated vehicle, a vehicle, a computer program and a computer-readable medium according to the appended claims.

Hence, according to an aspect of the present invention a method for controlling an articulated vehicle is provided. The articulated vehicle comprises: a front vehicle section and a rear vehicle section; an articulation unit allowing the front vehicle section and the rear vehicle section to pivot in relation to each other; and a damping arrangement arranged to control the pivotal movement about the articulation unit. The method comprises the steps of: identifying an intention to turn the vehicle, determining if any external object would cause a dangerous situation if the intended turning of the vehicle is realised, and if so controlling the damping arrangement, such that pivotal movement about the articulation unit is impeded.

The front vehicle section of the articulated vehicle may comprise a front axle with front wheels connected to the steering wheel of the vehicle. The front wheels may thus be referred to as steered wheels. The front vehicle section may also comprise an intermediate axle arranged between the front axle and the articulation unit. The rear vehicle section comprises a rear axle with rear wheels. The rear axle may be the driving axle and the rear wheels may thus be referred to as driving wheels. The articulation unit is a joint mechanism which connects the front vehicle section and the rear vehicle section and allows them to pivot in relation to each other. In order to be able to turn the vehicle articulation about the articulation unit is required. The damping arrangement may be arranged to reduce the horizontal movement between the front vehicle section and the rear vehicle section. When no damping is provided, the front vehicle section and the rear vehicle section can pivot freely in relation to each other. With no damping the risk for jack-knifing is increased. With maximum damping pivotal movement about the articulation unit is more or less prevented. When it has been identified that the operator of the vehicle intends to turn the vehicle and that turning the vehicle would lead to a dangerous situation, the damping arrangement of the vehicle is controlled, such that pivotal movement about the articulation unit is impeded or even prevented. Thus, the damping arrangement is suitably controlled, such that the articulation unit becomes stiff/rigid and the vehicle will no longer act as an articulated vehicle. Turning the vehicle will thereby become very difficult since the intermediate axle must be dragged sideways. Thus, by controlling the damping arrangement to impede/reduce pivotal movement, turning the vehicle will be difficult or even impossible and the determined dangerous situation can thereby be avoided. This way, the number of accidents in the traffic will be reduced. Also, by only affecting the possibility to turn the vehicle the vehicle can be operated in the original travel direction until the dangerous situation is over.

The damping arrangement suitably comprises at least one damping means. The at least one damping means may be a damping cylinder. The damping cylinder may comprise a fluid reservoir and a reciprocating piston arranged in the reservoir. The reservoir and the piston form a chamber on each side of the piston. The damping cylinder may be configured, such that a fluid in the reservoir can flow between the two chambers, where the direction of the flow depends on whether the piston is pushed inwards in the reservoir or if the piston is pulled outwards. The damping arrangement may comprise at least one proportional valve unit arranged to regulate the flow of fluid between the two different chambers and thereby regulate the hydraulic pressure on the piston. The hydraulic pressure on the piston determines the damping. Thus, the step of controlling the damping arrangement to impede pivotal movement about the articulation unit suitably comprises to control the proportional valve unit. The proportional valve unit may be a solenoid valve unit controlled by a control current provided by a control unit. A control current thus controls the proportional valve unit between different open or closed states. The control current supplied to the proportional valve unit may be a variable control current and normally depends on the vehicle speed, steering angle, articulation angle, articulation angle rate and similar. The control current used for controlling the proportional valve unit controls the damping effect of the damping cylinder. For example, a high control current may correspond to a closed state of the proportional valve unit. A closed state of the proportional valve unit may be a completely closed state or an essentially closed state. A closed state may thus allow a limited flow of fluid to flow between the chambers. When the proportional valve unit is in a closed state the fluid in the reservoir is obstructed to flow between the chambers and the hydraulic pressure on the piston is high. The fluid will thus apply a force on the piston in a direction opposite to the force caused by the pivotal movement of the two vehicle sections. The fluid will thereby impede the movement of the piston and the damping cylinder will thereby provide a high damping on the articulation unit. Similarly, a low control current may correspond to an open state of the proportional valve unit. When the proportional valve unit is in an open state the fluid in the reservoir can more easily flow between the two chambers when the piston is moving, which thus results in a low damping on the articulation unit.

By turning the vehicle is meant to at least temporarily change the travel direction of the vehicle. Turning the vehicle thus suitably comprises to turn the steering wheel and the steered wheels linked to the steering wheel. Turning the vehicle may also be referred to as a lateral displacement of the vehicle. Turning the vehicle may comprise to change lane, turn in an intersection, leaving a bus stop etc.

According to an embodiment of the invention an intention to turn the vehicle is identified based on the steering angle, the status of the flashers, the vehicle speed, the position of the accelerator pedal, the status of the brakes and/or the status of the gearbox of the vehicle. The steering angle is suitably defined as the angle of the steering wheel in relation to a zero position. In the zero position the steering wheel is directed such that the steered front wheels of the vehicle are directed essentially in parallel with the longitudinal extension of the vehicle. Thus, when the operator of the vehicle intends to turn the vehicle the operator turns the steering wheel to achieve a positive or negative steering angle in relation to the zero position. Suitably, when the operator of the vehicle intends to turn the vehicle the operator activates a flasher indicating the direction of the turn. Thus, if a flasher is activated an intention to turn the vehicle may be identified. The vehicle speed may also indicate an intention to turn, suitably as a factor together with the steering angle and/or the status of the flashers. Depending on the situation, the vehicle speed may or may not indicate an intention to turn the vehicle. For example, a vehicle with a vehicle speed that is essentially zero typically has no immediate intention to turn. The vehicle cannot be turned as long as the vehicle stands still. Thus, an operator may prepare for a turn by changing the steering angle and by activating a flasher but as long as the vehicle is standing still there is no risk for a dangerous situation and the damping arrangement does not have to be controlled to impede pivotal movement. However, if the vehicle has a vehicle speed different from zero and at the same time changes the steering angle and/or activates a flasher, it is clear that the vehicle is about to turn and the safety precaution of controlling the damping arrangement is suitably performed. Similarly, the position of the accelerator pedal, the status of the brakes and the status of the gearbox can be used to determine if there is an intention to turn the vehicle. If the vehicle has been standing still, for example at a bus stop or in an intersection, and the brakes are released, the accelerator pedal is depressed and/or a gear is engaged, this indicates that the vehicle is about to turn. The steering angle, the status of the flashers, the vehicle speed, the position of the accelerator pedal, the status of the brakes and/or the status of the gearbox of the vehicle is suitably determined by means of vehicle internal sensor means, control units and/or systems.

According to an embodiment of the invention an intention to turn the vehicle is identified based on a bus schedule associated with the vehicle. In the case where the vehicle is an articulated bus the bus schedule associated with the vehicle may indicate that it is time to leave the bus stop and thereby turn the vehicle.

External objects that might cause a dangerous situation may be determined by means of sensor means, such as cameras, lidar, radar or similar. By such sensor means objects in the surroundings of the vehicle can be identified and it can be concluded if they constitute a potential risk or not. The sensor means may be adapted to determine if an external object is moving with constant speed or if the object is decelerating. The sensor means may be adapted to determine if the vehicle will cross the travel direction of an external object when the vehicle performs the intended turn. The sensor means may be adapted to determine if the vehicle will interfere with an external object when the vehicle performs the intended turn.

According to an aspect of the invention the intention to turn the vehicle relates to a change of lane. The external object that would cause a dangerous situation may thus be an overtaking vehicle. When changing lane it may be difficult for the operator to notice vehicles approaching from behind. It is particularly difficult to notice vehicles in the blind spot. Vehicles approaching from behind may thus constitute external objects that would cause a dangerous situation if the vehicle turns. With modern technology it is, however, possible to identify such objects. The approaching vehicle is particularly a risk object if the vehicle speed of the approaching vehicle is constant. That typically means that the operator of the approaching vehicle has not noticed the turning vehicle and there is a risk that the two vehicles will collide. If the approaching vehicle is decelerating, the operator of the approaching vehicle has most likely noticed the turning vehicle and there is less risk that the two vehicles will collide. Thus, an approaching vehicle with a constant vehicle speed may be determined as an external object that would cause a dangerous situation if the intended turning of the vehicle is realised, while an approaching decelerating vehicle may not be considered to be an external object that would cause a dangerous situation of the intended turning of the vehicle is realised.

A change of lane may also relate to a bus leaving a bus stop. Thus, according to an embodiment of the invention the intention to turn the vehicle relates to leaving a bus stop. In this case the vehicle intending to turn is an articulated bus. The external object that would cause a dangerous situation may still be an overtaking vehicle. That is, an object that would cause a dangerous situation may be a vehicle approaching from behind in the lane next to the bus stop. It may be difficult for the operator to notice vehicles approaching from behind when leaving the bus stop. It is particularly difficult to notice vehicles in the blind spot. In some countries, during certain traffic conditions, approaching vehicles should always give way for buses leaving a bus stop. The operator of the bus can, however, not trust that this will always be the case and an approaching vehicle may therefore constitute an external factor that would cause a dangerous situation. An approaching vehicle with a constant vehicle speed may be determined as an external object that would cause a dangerous situation if the intended turning of the vehicle is realised, while an approaching decelerating vehicle may not be considered to be an external object that would cause a dangerous situation of the intended turning of the vehicle is realised.

According to an embodiment of the invention the intention to turn the vehicle relates to a turn in an intersection. An external object that would cause a dangerous situation may thus be a cyclist or mopedist positioned next to (adjacent) the vehicle. An object positioned along the side of a vehicle may be difficult to notice due to the A-pillar of the vehicle. Another external object that would cause a dangerous situation may be a pedestrian or an animal crossing the road, which the vehicle is intending to turn to. Suitably, objects positioned, such that the vehicle would traverse the travel direction of the object when turning, are considered to constitute external factors that would cause a dangerous situation.

According to an embodiment of the invention the method further comprises to inform an operator of the vehicle of the dangerous situation. The step of informing the operator may be performed prior to controlling the damping arrangement or essentially at the same time as controlling the damping arrangement. This way, the operator of the vehicle will be informed that a dangerous situation is about to happen if the vehicle is turned and the operator can take suitable actions to avoid the dangerous situation. The method may comprise to provide an alert visually on a display, for example on the control panel. The method may alternatively or additionally comprise to provide an audial alert and/or a tactile alert. A tactile alert may be vibrations in the seat, the steering wheel or similar. An alert may also be provided visually in a rearview mirror. The information about the dangerous situation may also be presented by augmented reality. In one embodiment of the invention the method comprises to inform the operator of the dangerous situation and if it is determined that the operator still intend to turn the vehicle, the damping arrangement is controlled to impede pivotal movement about the articulation unit.

According to an embodiment of the invention the method further comprises to control the vehicle speed if it is determined that an external object would cause a dangerous situation. This way, it is ensured that the operator is made aware of the dangerous situation. The vehicle speed is suitably controlled, such that the vehicle speed is reduced. A reduced vehicle speed may be obtained by controlling the brakes of the vehicle and/or by controlling the throttle. Thus, the method may comprise to activate a vehicle brake and/or release the accelerator throttle.

According to an aspect of the invention a system for controlling an articulated vehicle is provided. The vehicle comprises: a front vehicle section and a rear vehicle section; an articulation unit allowing the front vehicle section and the rear vehicle section to pivot in relation to each other; and a damping arrangement arranged to control the pivotal movement about the articulation unit; wherein the system comprises a control unit. The control unit comprises: means for identifying an intention to turn the vehicle, means for determining if any external object would cause a dangerous situation if the intended turning of the vehicle is realised, and means for controlling the damping arrangement, such that pivotal movement about the articulation unit is prevented.

A control unit is to be interpreted herein as a unit comprising control logic capable of exchanging digital data with other control units. The control unit may comprise a single control unit or a plurality of control units.

The means for identifying an intention to turn the vehicle; the means for determining if any external object would cause a dangerous situation if the intended turning of the vehicle is realised; and the means for controlling the damping arrangement, such that pivotal movement about the articulation unit is prevented, may e.g. be different software modules/portions in the control unit, program code, algorithms or similar.

It will be appreciated that all the embodiments described for the method aspect of the invention are also applicable to the system aspect of the invention. That is, the control unit of the system for controlling an articulated vehicle may be configured to perform any one of the steps of the method according to various embodiments described herein.

Further objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following details, and also by putting the invention into practice. Whereas embodiments of the invention are described below, it should be noted that it is not restricted to the specific details described. Specialists having access to the teachings herein will recognise further applications, modifications and incorporations within other fields, which are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS For fuller understanding of the present invention and further objects and advantages of it, the detailed description set out below should be read together with the accompanying drawings, in which the same reference notations denote similar items in the various drawings, and in which: Figure 1 schematically illustrates an articulated vehicle according to an embodiment of the invention; Figure 2 schematically illustrates a system for controlling an articulated vehicle according to an embodiment of the invention; Figures 3a-c schematically illustrate different driving situations related to the inventive method according to embodiments of the invention; Figure 4 illustrates a flow chart for a method for controlling an articulated vehicle according to an embodiment of the invention; and Figure 5 schematically illustrates a control unit or computer according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS The term “link” refers herein to a communication link which may be a physical connection such as an opto-electronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.

The herein mentioned term “external object” relates to objects in the surrounding of the vehicle. The external objects may comprise moving objects and/or non-moving objects. Said objects may be structures, such as roads, pavements, buildings etc. The objects may alternatively be vehicles, pedestrians, cyclists, other road users or animals.

The herein mentioned term "dangerous situation” relates to a situation where there is a risk that the vehicle will interfere in some way with another object. Interfering with another object suitably means that the vehicle collides with an object. Interfering may mean to disturb the performance of the vehicle and/or the performance of the object.

Figure 1 schematically illustrates a side view of a wheeled articulated vehicle 1 according to an embodiment of the invention. The exemplified vehicle 1 is an articulated bus in the shape of an accordion bus. The vehicle 1 comprises a propulsion unit 2 for driving the vehicle 1, a front vehicle section 4 and a rear vehicle section 6. The vehicle 1 further comprises an articulation unit 8 arranged to connect the front vehicle section 4 and the rear vehicle section 6 and to allow the two vehicle sections 4, 6 to pivot in relation to each other. The front vehicle section 4 comprises a front axle 10 with front wheels 12. The vehicle has a steering wheel SW connected to the front axle 10 and the front wheels 12. The front wheels 12 may thus be referred to as steered wheels 12. By turning the steering wheel SW and thereby changing the steering angle a corresponding change in the front wheels 12 will be generated. The vehicle 1 further comprises an intermediate axle 14 with intermediate wheels 16. The intermediate axle 14 is arranged on the front vehicle section 4 in front of the articulation unit 8. The rear vehicle section 6 comprises a rear axle 18 with rear wheels 20. The rear axle 18 is suitably connected to the propulsion unit 2 and is thus a drive axle. The rear wheels 20 may thereby be referred to as driving wheels 20.

The propulsion unit 2 of the vehicle 1 is suitably arranged at the rear vehicle section 6. The vehicle 1 may thus be referred to as a pusher bus. The configuration with the propulsion unit 2 at the rear end of the vehicle 1 makes more room for passengers and a better distribution of the passengers in the bus. Challenges does, however, come with this type of design as it makes the weight of the vehicle 1 uneven with a great amount on the driving axle 18, leaving the intermediate axle 14 with less weight, pressure and grip. This may increase the risk of jack-knifing when making a turn or when driving downhill on a slippery slope. The vehicle 1 may therefore comprise a damping arrangement 50 arranged to control the pivotal movement about the articulation unit 8. The damping arrangement 50 suitably comprises two damping cylinders (not shown) and a control unit (not shown) for controlling the damping effect of the damping cylinders.

The vehicle 1 may further comprise a system 100 for controlling an articulated vehicle. The system 100 may comprise a control unit 200, which may comprise the control unit of the damping arrangement 50 or any other control unit associated with the vehicle 1.

Figure 2 schematically illustrates a system 100 for controlling an articulated vehicle according to an embodiment of the invention. The system 100 is suitably adapted for controlling an articulated vehicle 1 as disclosed in Figure 1. The system 100 comprises a control unit 200. The control unit 200 comprises: means for identifying an intention to turn the vehicle 1 ; means for determining if any external object would cause a dangerous situation if the intended turning of the vehicle 1 is realised; and means for controlling the damping arrangement 50, such that pivotal movement about the articulation unit 8 is prevented. The means for identifying an intention to turn the vehicle 1 ; the means for determining if any external object would cause a dangerous situation if the intended turning of the vehicle 1 is realised; and the means for controlling the damping arrangement 50, such that pivotal movement about the articulation unit is prevented, may e.g. be different software modules/portions in the control unit, program code, algorithms or similar.

The system 100 suitably comprises first sensor means 210 arranged in communication with the control unit 200. The control unit 200 is suitably arranged in communication with the first sensor means 210 via a link L210. The first sensor means 210 may comprise a plurality of sensors. The first sensor means 210 may comprise sensors for determining the vehicle speed; sensors for determining the steering angle, sensors for determining the status of the flashers, sensors for determining the status of the brakes and sensors for determining the status of the gearbox. The first sensors means 210 may be arranged in communication with the control unit 200 via other control units or via a CAN bus or similar. Based on signals from the first sensor means 210 the control unit 200 can identify an intention to turn the vehicle 1.

The system 100 suitably further comprises second sensor means 220 arranged in communication with the control unit 200. The control unit 200 is suitably arranged in communication with the second sensor means 220 via a link L220. The second sensor means 220 may comprise a plurality of sensors. The second sensor means 220 may comprise sensors for observing the surroundings of the vehicle 1. The second sensor means 220 may comprise sensors for determining if an object in the surroundings of the vehicle is moving with constant speed or if it is decelerating. The second sensor means 220 may comprise cameras, lidar, radar or similar. The second sensors means 220 may be arranged in communication with the control unit 200 via other control units or via a CAN bus or similar. Based on signals from the second sensor means 220 the control unit 200 can determine if any external object would cause a dangerous situation if the intended turning of the vehicle 1 is realised.

The control unit 200 of the system 100 is suitably arranged in communication with the damping arrangement 50 of the vehicle 1. The control unit 200 may be arranged for communication with said damping arrangement 50 via a link L50. The control unit 200 may alternatively constitute a control unit of the damping arrangement 50. The control unit 200 may be adapted to control a pivotal movement about an articulation unit 8 of an articulated vehicle 1 as disclosed in Figure 1. The control unit 200 may thus be adapted to control at least one hydraulic damping means arranged to dampen a pivotal movement about the articulation unit 8. The control unit 200 may be adapted to control at least one proportional valve unit arranged to regulate the damping effect of the at least one damping means, by supplying a control current to the proportional valve unit. The control unit 200 may thus be arranged in communication with the proportional valve unit of the damping arrangement 50. The control unit 200 is suitably adapted to control the damping arrangement 50, such that pivotal movement about the articulation unit 8 is impeded.

The system 100 may further comprise means 230 for informing the operator of the vehicle 1 about the dangerous situation that might occur if the vehicle 1 turns. The means 230 for informing the operator of the vehicle 1 are suitably arranged in communication with the control unit 200 via a link L230. The means 230 for informing the operator may comprise means for providing a visual alert to the operator. The means 230 for informing the operator may comprise means for providing an audial alert to the operator. The means 230 for informing the operator may comprise means for providing a tactile alert.

The control unit 200 of the system 100 may also be arranged in communication with other systems 240 of the vehicle 1. The control unit 200 may be arranged in communication with said other systems 240 via link L240.

Such systems 240 may comprise an engine control system, a brake control system, a transmission control system or similar.

A computer 205 may also be arranged for communication with the control unit 200 via a link L205 and may be detachably connected to it. The computer 205 may be adapted to conduct the innovative method steps according to the invention. The computer 205 may be used to cross-load software to the control unit 200, particularly software for conducting the innovative method. The computer 205 may alternatively be arranged for communication with the control unit 200 via an internal network on board the vehicle. The innovative method as described in Figure 4 may be conducted by the control unit 200 or the computer 205, or by both of them.

Figures 3a-3c schematically illustrate a vehicle in different situations according to embodiments of the invention. The situations suitably relate to the inventive method as described in Figure 4. The vehicle is suitably a vehicle 1 as disclosed in Figure 1 and the vehicle 1 thus comprises a system as disclosed in Figure 2.

Figure 3a schematically illustrates the vehicle 1 in a first situation according to an embodiment of the invention. The vehicle 1 has stopped at a bus stop H and the vehicle 1 may thus be an articulated bus. An external object 110 is approaching the vehicle 1 from behind. The external object 110 is suitably an approaching vehicle. The external object 110 may be an overtaking vehicle 110. The approaching vehicle 110 would cause a dangerous situation if the vehicle 1 turns out to the same lane as the approaching vehicle 110 and if the approaching vehicle 110 does not give way for the articulated vehicle 1. Vehicles approaching from behind may be very difficult to notice in the rearview mirrors. A vehicle in the blind spot may even be impossible to see. A system 100 for controlling an articulated vehicle 1 as disclosed in Figure 2 is therefore advantageous to ensure safety. If the system 100 identifies an intention to turn the vehicle 1 and if the system 100 determines that the approaching vehicle 110 is not slowing down, the damping arrangement 50 of the vehicle 1 is suitably controlled, such that pivotal movement about the articulation unit 8 is impeded or prevented. This way, turning the vehicle 1 will be difficult and the dangerous situation may be avoided. An intention to turn the vehicle 1 is suitably identified by means of the first sensor means 210 and whether the approaching vehicle 110 is slowing down or not is suitably determined by means of the second sensor means 220 as described in Figure 2.

An intention to turn the vehicle 1 may be identified based on the steering angle. In one example the vehicle 1 is standing still and the operator has turned the steering wheel SW such that the steered wheels 12 are directed towards the lane adjacent the bus stop H. The operator may also have activated the left flasher to show the intent to turn. Thus, the activated flasher and the steering angle may indicate an intention to turn the vehicle 1 and the approaching vehicle 110 may thereby be considered to cause a dangerous situation. Turning the vehicle 1 may then be impeded by controlling the damping arrangement 50. However, the steering angle and the left flasher may only be preparations for turning the vehicle 1 and the operator may in fact not intend to turn the vehicle 1 until the approaching vehicle 110 has passed. Suitably, it is not until the operator of the vehicle 1 releases the brakes and/or starts depressing the accelerator pedal that it is clear that the operator intends to turn the vehicle 1. Thus, when the brakes are released and/or the accelerator is depressed an intention to turn the vehicle 1 is identified, the approaching vehicle 110 would cause a dangerous situation and the damping arrangement 50 is controlled to impede the intended turning of the vehicle 1.

Figure 3b schematically illustrates the vehicle 1 in a second situation according to an embodiment of the invention. The vehicle 1 is operated for example on a highway and intends to perform a lane change to the left at right-hand traffic. An external object 110 is approaching the vehicle 1 from behind. The external object 110 is suitably an approaching vehicle 110. The external object 110 may be an overtaking vehicle 110. The approaching vehicle 110 would cause a dangerous situation if the vehicle 1 turns left into the same lane as the approaching vehicle 110 and if the approaching vehicle 110 does not give way for the vehicle 1. A system 100 for controlling an articulated vehicle 1 as disclosed in Figure 2 is therefore advantageous to ensure safety. If the system 100 identifies an intention to turn the vehicle 1 and if the system 100 determines that the approaching vehicle 110 is not slowing down, the damping arrangement 50 of the vehicle 1 is suitably controlled, such that pivotal movement about the articulation unit 8 is impeded or prevented. This way, turning the vehicle 1 will be difficult and the dangerous situation may be avoided. An intention to turn the vehicle 1 is suitably identified by means of the first sensor means 210 and whether the approaching vehicle 110 is slowing down or not is suitably determined by means of the second sensor means 220 as described in Figure 2.

An intention to turn the vehicle 1 may in this situation be identified based on the activation of the left flasher and/or the steering angle. Since the vehicle 1 is moving, changing the steering angle by turning the steering wheel SW to the left will immediately move the vehicle 1 to the left. For ensuring safety the activated flasher may be considered to, alone, indicate that the operator intends to turn the vehicle 1. Thus, when the left flasher is activated it is determined if the approaching vehicle 110 may be be considered to cause a dangerous situation based on the speed of the approaching vehicle 110. If the approaching vehicle 110 has an essentially constant speed, there is no intention to give way for the vehicle 1 and a dangerous situation may thereby occur. The damping arrangement 50 may thereby be controlled to impede the intended turning of the vehicle 1 and the dangerous situation can be avoided.

Figure 3c schematically illustrates the vehicle 1 in a third situation according to an embodiment of the invention. The vehicle 1 is approaching an intersection at right-hand traffic and intends to turn right at the intersection. In one example an external object 110a is situated to the right of the vehicle 1 and intends to move straight ahead. The external object 110a may be a cyclist or moped rider. This object 110a may be determined to cause a dangerous situation if the vehicle 1 turns right. Objects positioned to the right of a large vehicle may be very difficult for the operator to notice and there is a risk that the vehicle 1 would collide with the object 110a as the vehicle 1 turns right. In another example an external object 110b crosses the lane, which the vehicle 1 intends to get into. The external object 110b may be a pedestrian walking on a crossing or an animal crossing the road. Such external object 110b might cause a dangerous situation if the vehicle 1 turns right. A system 100 for controlling an articulated vehicle 1 as disclosed in Figure 2 is therefore advantageous to ensure safety related the turning of the vehicle 1. If the system 100 identifies an intention to turn the vehicle 1 and if the system 100 determines that there is an external object 110a, 110b, which will cause a dangerous situation as the vehicle 1 turns, the damping arrangement 50 of the vehicle 1 is suitably controlled to impede or prevent pivotal movement about the articulation unit 8. This way, turning the vehicle 1 to the right will be difficult and the dangerous situation can be avoided. An intention to turn the vehicle 1 is suitably identified by means of the first sensor means 210 and the external objects 110a, 110b that would cause a dangerous situation are suitably determined by means of the third sensor means 220.

An intention to turn the vehicle 1 may in this situation be identified based on the steering angle and/or the activated right flasher. Thus, the damping arrangement 50 may be controlled to impede or prevent pivotal movement about the articulation unit 8 if the steering angle and/or the right flasher indicate that the vehicle 1 intends to turn right and if an external object 110a, 110b has been identified. However, if the vehicle 1 is standing still and the operator has turned the steering wheel SW and activated the right flasher to prepare for the turn, the damping arrangement 50 may be controlled to allow pivotal movement about the articulation unit 8. Suitably, it is not until the operator of the vehicle 1 releases the brakes and/or starts depressing the accelerator pedal that it is clear that the operator intends to turn the vehicle 1 and that a dangerous situation would occur. Thus, when the brakes are released and/or the accelerator is depressed an intention to turn the vehicle 1 is identified, the external object 110a, 110b would cause a dangerous situation and the damping arrangement 50 is controlled to impede the intended turning of the vehicle 1.

Figure 4 illustrates a flow chart for a method for controlling an articulated vehicle according to an embodiment of the invention. The articulated vehicle is suitably configured as the vehicle 1 disclosed in Figure 1 and thus comprises: a front vehicle section 4 and a rear vehicle section 6; an articulation unit 8 allowing the front vehicle section 4 and the rear vehicle section 6 to pivot in relation to each other; and a damping arrangement 50 arranged to control the pivotal movement about the articulation unit 8. The method comprises the steps of: identifying s101 an intention to turn the vehicle 1 ; determining s102 if any external object 110, 110a, 110b would cause a dangerous situation if the intended turning of the vehicle 1 is realised; and if so, controlling s103 the damping arrangement 50, such that pivotal movement about the articulation unit 8 is impeded.

Controlling s103 the damping arrangement 50, such that pivotal movement about the articulation unit 8 is impeded suitably comprise to control the damping arrangement 50, such that the articulation unit 8 becomes stiff/rigid. This way, the vehicle 1 will no longer behave as an articulated vehicle. Turning the vehicle 1 will thereby become very difficult since the intermediate axle 14 must be dragged sideways.

The method according to the invention is suitably performed by means of a system for controlling an articulated vehicle 1 as disclosed in Figure 2. The system 100 comprises a control unit 200, which suitably is adapted to perform the herein described method steps.

The step of identifying s101 an intention to turn the vehicle 1 may be based on the steering angle, the status of the flashers, the vehicle speed, the position of the accelerator pedal, the status of the brakes and/or the status of the gearbox of the vehicle 1. The step of identifying s101 an intention to turn the vehicle 1 may thus comprise to determine the steering angle, the status of the flashers, the vehicle speed, the position of the accelerator pedal, the status of the brakes and/or the status of the gearbox of the vehicle 1. Turning the steering wheel and activating a flasher may be obvious indicators that the vehicle 1 is about to turn and an intention to turn the vehicle 1 may thus be based on these factors. However, sometimes the operator of the vehicle 1 prepares the vehicle 1 for turning by changing the steering angle and by activating a flasher when the vehicle is standing still. There is thus no immediate risk for a dangerous situation. In such cases it may be unnecessary to impede pivotal movement until the operator releases the brakes, depresses the accelerator pedal and/or engages a gear.

The step of identifying s101 an intention to turn the vehicle 1 may be based on a bus schedule associated with the vehicle 1. In the case where the vehicle 1 is an articulated bus as disclosed in Figure 3a the bus schedule associated with the vehicle 1 may indicate that it is time to leave the bus stop H and thereby turn the vehicle 1.

The step of determining s102 if any external objects 110, 110a, 110b would cause a dangerous situation if the vehicle 1 is turned may comprise to determine the presence of objects 110, 110a, 110b in the surroundings of the vehicle 1 and to conclude if they constitute a potential risk or not. The step of determining s102 if any external objects 110, 110a, 110b would cause a dangerous situation if the vehicle 1 is turned may comprise to determine if the vehicle 1 will cross the travel direction of an external object 110, 110a, 110b or if the vehicle 1 will interfere with an external object 110, 110a, 110b when the intended turn is realised. The step of determining s102 if any external objects 110, 110a, 110b would cause a dangerous situation if the vehicle 1 is turned may comprise to determine if an approaching vehicle 110 is decelerating or if it has an essentially constant vehicle speed. The step of determining s102 if any external objects 110, 110a, 110b would cause a dangerous situation if the vehicle 1 is turned may be performed by means of second sensor means 220, such as cameras, lidar, radar or similar.

The method may further comprise to inform an operator of the vehicle of the dangerous situation. The step of informing the operator may be performed prior to controlling s103 the damping arrangement or essentially at the same time as controlling s103 the damping arrangement. This way, the operator of the vehicle will be informed that a dangerous situation is about to happen if the vehicle 1 is turned and the operator can take suitable actions to avoid the dangerous situation. The step of informing the operator may comprise to provide an alert visually on a display, for example on the control panel. The step of informing the operator may alternatively or additionally comprise to provide an audial alert and/or a tactile alert. A tactile alert may be vibrations in the seat, the steering wheel or similar. The step of informing the operator may comprise to provide an alert visually in a rear-view mirror or by augmented reality. In the case where the method comprises to inform the operator of the dangerous situation prior to impeding pivotal movement about the articulation unit 8, the operator may perform actions, such that the identified intention to turn the vehicle 1 no longer is valid. The damping arrangement 50 will thereby not be controlled to impede the pivotal movement about the articulation unit 8. However, if the operator does not respond to the alert the damping arrangement 50 will be controlled to impede pivotal movement about the articulation unit 8.

The method may also comprise to control the vehicle speed if it is determined that an external object 110, 110a, 110b would cause a dangerous situation if the vehicle 1 turns. This way, it is ensured that the operator is made aware of the dangerous situation and the dangerous situation may be avoided. The method suitably comprises to reduce the vehicle speed if it is determined that an external object 110, 110a, 110b would cause a dangerous situation if the vehicle 1 turns. Reducing the vehicle speed may comprise controlling the brakes of the vehicle 1 and/or to control the throttle. Thus, the step of controlling the vehicle speed may comprise to activate a vehicle brake and/or release the accelerator throttle.

Figure 5 is a diagram of a version of a device 500. The control unit 200 and/or computer 205 described with reference to Figure 2 may in a version comprise the device 500. The term “link” refers herein to a communication link which may be a physical connection such as an optoelectronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link. The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer programme, e.g. an operating system, is stored for controlling the function of the device 500. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted). The non-volatile memory 520 has also a second memory element 540.

There is provided a computer programme Pr which comprises routines for controlling an articulated vehicle. The computer programme Pr comprises routines for identifying an intention to turn the vehicle. The computer programme Pr comprises routines for determining if any external objects would cause a dangerous situation if the intended turn is realised. The computer programme Pr comprises routines for controlling a damping arrangement, such that pivotal movement about an articulation unit is impeded.

The programme Pr may be stored in an executable form or in a compressed form in a memory 560 and/or in a read/write memory 550.

Where the data processing unit 510 is described as performing a certain function, it means that the data processing unit 510 effects a certain part of the programme stored in the memory 560 or a certain part of the programme stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511. The read/write memory 550 is adapted to communicating with the data processing unit 510 via a data bus 514.

When data are received on the data port 599, they are stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 is prepared to effect code execution as described above.

Parts of the methods herein described may be effected by the device 500 by means of the data processing unit 510 which runs the programme stored in the memory 560 or the read/write memory 550. When the device 500 runs the programme, methods herein described are executed.

The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to restrict the invention to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order best to explain the principles of the invention and its practical applications and hence make it possible for specialists to understand the invention for various embodiments and with the various modifications appropriate to the intended use.

Claims

1. A method for controlling an articulated vehicle (1), the articulated vehicle (1) comprising: a front vehicle section (4) and a rear vehicle section (6); an articulation unit (8) allowing the front vehicle section (4) and the rear vehicle section (6) to pivot in relation to each other; and a damping arrangement (50) arranged to control the pivotal movement about the articulation unit (8); the method comprising the steps of: - identifying (s101) an intention to turn the vehicle (1); - determining (s102) if any external object (110, 110a, 110b) would cause a dangerous situation if the intended turning of the vehicle (1) is realised; and if so - controlling (s103) the damping arrangement (50), such that pivotal movement about the articulation unit (8) is impeded.

2. The method according to claim 1, wherein an intention to turn the vehicle (1) is identified based on the steering angle, the vehicle speed, the position of the accelerator pedal, the status of the flashers, the status of the brakes and/or the status of the gearbox of the vehicle.

3. The method according to claim 1 or 2, wherein an intention to turn the vehicle (1) is identified based on a bus schedule associated with the vehicle (1).

4. The method according to any of the preceding claims, wherein the intention to turn the vehicle (1) relates to a change of lane.

5. The method according to any of the preceding claims, wherein an external object (110) that would cause a dangerous situation is an overtaking vehicle.

6. The method according to any of claims 1-3, wherein the intention to turn the vehicle (1) relates to a turn in an intersection.

7. The method according to any of the preceding claims, wherein the method further comprises to inform an operator of the vehicle (1) of the dangerous situation.

8. The method according to any of the preceding claims, wherein the method further comprises to control the vehicle speed if it is determined that an external object (110, 110a, 110b) would cause a dangerous situation.

9. A computer program (Pr), wherein said computer program comprises programme code for causing a control unit (200; 500) or a computer (205; 500) connected to the control unit (200; 500) to perform the method according to any one of the preceding claims.

10. A computer-readable medium comprising instructions, which when executed by a control unit (200; 500) or a computer (205; 500) connected to the control unit (200; 500), cause the control unit (200; 500) or the computer (205; 500) to perform the method according to any one of claims 1 -8.

11. A system (100) for controlling an articulated vehicle (1), the vehicle (1) comprising: a front vehicle section (4) and a rear vehicle section (6); an articulation unit (8) allowing the front vehicle section (4) and the rear vehicle section (6) to pivot in relation to each other; and a damping arrangement (50) arranged to control the pivotal movement about the articulation unit (8); wherein the system (100) comprises a control unit (200), the control unit (200) comprising: - means for identifying an intention to turn the vehicle (1); - means for determining if any external object (100, 100a, 100b) would cause a dangerous situation if the intended turning of the vehicle (1) is realised; and - means for controlling the damping arrangement (50), such that pivotal movement about the articulation unit (8) is impeded.

12. An articulated vehicle (1), comprising a system (100) according to claim 11.