Method for controlling a combination of vehicles

Abstract

The invention relates to a method for controlling a vehicle combination (10) comprising a towing vehicle (12) and a trailer (14). The tractor (12) includes a set of tractor wheels (16, 18, 20, 22) and the trailer (14) includes a set of trailer wheels (26, 28, 32, 34). The tractor (12) comprises a set of tractor motion support means (36, 38, 40, 42) comprising at least one tractor motion support means connectable to the set of tractor wheels (16, 18, 20, 22) so as to provide at least a tractor force, the tractor force being at least one of a tractor propulsive force and a tractor braking force; and the trailer (14) comprises a set of trailer movement support means (44, 46, 48) comprising at least one trailer movement support means connectable to the set of trailer wheels (26, 28, 32, 34) so as to provide at least a trailer force, the trailer force being at least one of a trailer propulsion force and a trailer braking force. The method comprises:-receiving a request that a desired force applied on the combination of vehicles (10) should be provided by a set of motion support devices of a unique dedicated unit of the combination of vehicles (10), the unique dedicated unit being a tractor (12) or a trailer (14); upon determining that the set of motion support means of the uniquely dedicated unit is capable of providing a desired force exerted on the combination of vehicles (10) when each of a predetermined set of safety requirements of the combination of vehicles (10) is met, operating only the set of motion support means of the uniquely dedicated unit in order to provide the desired force; otherwise, one or more of the tractor (12) motion support means and one or more of the trailer (14) motion support means are operated in order to provide the desired force exerted on the vehicle combination (10), where the predetermined set of safety requirements includes at least one safety requirement.

Description

Technical Field

[0001] Furthermore, the invention relates to a method for controlling a vehicle combination. Furthermore, the invention relates to each of a computer program, a computer readable medium, a control unit and a vehicle combination.

[0002] The present invention is applicable to heavy vehicles such as trucks, buses and construction equipment. Although the present invention will be described with respect to a truck, the present invention is not limited to this particular vehicle but may also be used in other vehicles such as transporters, cars and the like. Background Art

[0003] A vehicle combination usually includes a tractor and a trailer. Traditionally, the tractor provides propulsion for the vehicle combination, and the tractor and trailer may be provided with brakes to ensure that the vehicle combination can be properly braked.

[0004] However, it is currently envisaged to use a vehicle combination in which each of the tractor and trailer comprises motion support means for propelling and braking the vehicle combination. To this end, although only as an example, each of the tractor and trailer may be equipped with a set of electric motors. Such electric motors may be connected to an electric power storage system, such as a battery.

[0005] Besides being able to propel vehicle combinations with little or even zero CO2 emissions, electric motors also have the advantage of being used for regenerative braking, where the energy generated during braking by means of the electric motor can be converted into electrical energy for storage in a selected electricity storage system.

[0006] Furthermore, for other variants of vehicle combinations that do not necessarily include electric motors, it may be desirable to control the force distribution between the motion support devices of the tractor and trailer. As a non-limiting example, it may be desirable to use only a limited number of service brakes at a time to ensure that the other service brakes can be adequately cooled.

[0007] As can be seen from the above, it is desirable to control the motion support devices of the tractor and trailer, respectively, in an appropriate manner to achieve the desired force distribution. Summary of the invention

[0008] The object of the present invention is to provide a method which makes it possible to control the force distribution between the tractor and the trailer in an appropriate manner.

[0009] This object is achieved by a method according to claim 1 .

[0010] The invention therefore relates to a method for controlling a vehicle combination. The vehicle combination comprises a tractor and a trailer. The tractor comprises a set of tractor wheels and the trailer comprises a set of trailer wheels. The tractor comprises a set of tractor motion support devices including at least one tractor motion support device, the set of tractor motion support devices being connectable to the set of tractor wheels and being adapted to provide at least a tractor force. The tractor force is at least one of a tractor propulsion force and a tractor braking force. The trailer comprises a set of trailer motion support devices including at least one trailer motion support device, the set of trailer motion support devices being connectable to the set of trailer wheels and being adapted to provide at least a trailer force. The trailer force is at least one of a trailer propulsion force and a trailer braking force.

[0011] The method comprises:

[0012] − receiving a request that a desired force exerted on said vehicle combination should be provided by said set of motion support means of a unique dedicated unit of said vehicle combination, said unique dedicated unit being said tractor vehicle or said trailer vehicle;

[0013] − upon determining that the set of motion support devices of the unique dedicated unit is capable of providing a desired force to be exerted on the vehicle combination when each of a predetermined set of safety requirements of the vehicle combination is met, operating only the set of motion support devices of the unique dedicated unit so as to provide the desired force, otherwise operating one or more of the tractor motion support devices and one or more of the trailer motion support devices so as to provide the desired force to be exerted on the vehicle combination, wherein the predetermined set of safety requirements includes at least one safety requirement.

[0014] As used herein, the term "operating only the set of kinematic support devices of the unique dedicated unit so as to provide the desired force" is intended to encompass operating only the set of kinematic support devices of the unique dedicated unit so as to provide the desired force. In other words, the term "operating only the set of kinematic support devices of the unique dedicated unit so as to provide the desired force" is intended to encompass not operating the set of kinematic support devices of the tractor or trailer that is not the unique dedicated unit.

[0015] The above method suggests a suitable way for determining when and how to use only the set of motion supporting devices of one unit of the vehicle combination to provide a desired force.

[0016] Optionally, the predetermined set of safety requirements for the vehicle combination includes a lateral acceleration safety condition, which requires that for each of the set of motion support devices of the unique dedicated unit, the longitudinal force generated by the motion support device must be equal to or lower than a longitudinal force limit value determined by a longitudinal force limit function, which is a function of at least the lateral acceleration of the unique dedicated unit.

[0017] Merely by way of example, said longitudinal force limit values ​​of each motion support device of a unique dedicated unit (ie a tractor or trailer) may be aggregated in order to obtain a longitudinal force limit value of the unique dedicated unit.

[0018] Optionally, the longitudinal force limit function is a function that uses as input a value proportional to the lateral acceleration of the unique dedicated unit and provides as output a value proportional to a normalized longitudinal force, the normalized longitudinal force being the longitudinal force divided by a total vertical load applied to one or more wheels connected to the motion support device and a friction value indicative of friction between the one or more wheels connected to the motion support device and a ground supporting the unique dedicated unit.

[0019] Optionally, the longitudinal force limit function uses as input the lateral acceleration of the unique dedicated unit divided by a friction reference value, which is a friction value indicative of the friction between the set of wheels of the unique dedicated unit and the ground supporting the unique dedicated unit multiplied by an acceleration value corresponding to the acceleration due to gravity.

[0020] Optionally, the longitudinal force limit function is a step function such that: when a value less than or equal to a predetermined threshold value obtained by dividing the lateral acceleration of the unique dedicated unit by the friction reference value is used as input, the output is set to a fixed non-zero value of the standardized longitudinal force; when a value greater than the predetermined threshold value obtained by dividing the lateral acceleration of the unique dedicated unit by the friction reference value is used as input, the output is set to zero.

[0021] Optionally, the predetermined set of safety requirements for the vehicle combination comprises a longitudinal slip safety condition requiring that detected longitudinal slip values ​​for at least a selected subset of the set of wheels of the unique dedicated unit be below a predetermined threshold.

[0022] Optionally, the predetermined set of safety requirements for the vehicle combination includes a state determination condition, which requires that for a predetermined vehicle state, the difference between a vehicle state measurement value associated with a measurement value indicating the predetermined vehicle state and a vehicle state expected value associated with an expected value indicating the predetermined vehicle state is within a predetermined state range.

[0023] Optionally, the expected value of the vehicle state is determined using a vehicle model of the vehicle combination, preferably, the expected value of the vehicle state is determined using a vehicle model and a tire model of the set of tractor wheels and / or the set of trailer wheels.

[0024] Optionally, said predetermined vehicle state is a yaw rate of said unique dedicated unit.

[0025] Optionally, the predetermined vehicle state is an articulation angle or an articulation angle change rate between the tractor and the trailer.

[0026] Optionally, said predetermined vehicle state is a sideslip angle of said unique dedicated unit.

[0027] Optionally, said predetermined vehicle state is a sideslip angle for at least a selected subset of said set of wheels of said unique dedicated unit.

[0028] Optionally, said desired force exerted on said vehicle is a propulsive force.

[0029] Optionally, said desired force exerted on said vehicle is a braking force.

[0030] Optionally, the vehicle combination comprises one or more additional trailers or dollies, each additional trailer comprising a set of additional trailer motion support devices including at least one additional trailer motion support device, the set of additional trailer motion support devices being connectable to the set of additional trailer wheels so as to be adapted to provide at least an additional trailer force, the additional trailer force being at least one of an additional trailer propulsion force and an additional trailer braking force. The method comprises:

[0031] − receiving a request that a desired force exerted on said vehicle combination should be provided by said set of motion support devices of a unique dedicated unit of said vehicle combination, said unique dedicated unit being one of said one or more additional trailers, said tractor vehicle or said trailer;

[0032] − upon determining that the set of motion support devices of the unique dedicated unit are capable of providing a desired force to be exerted on the vehicle combination when each of a predetermined set of safety requirements of the vehicle combination is met, only operating the set of motion support devices of the unique dedicated unit so as to provide the desired force, otherwise operating one or more of the tractor motion support devices and one or more of the trailer motion support devices and / or one or more of the additional trailer motion support devices of one or more of the one or more additional trailers so as to provide the desired force to be exerted on the vehicle combination, wherein the predetermined set of safety requirements includes at least one safety requirement.

[0033] A second aspect of the invention relates to a computer program comprising program code means for performing the steps of the method according to the first aspect of the invention when said program is run on a computer.

[0034] A third aspect of the invention relates to a computer readable medium carrying a computer program comprising program code means for executing the steps of the method according to the first aspect of the invention when the program product is run on a computer.

[0035] A fourth aspect of the invention relates to a control unit for controlling a vehicle, the control unit being configured to perform the steps of the method according to the first aspect of the invention.

[0036] A fifth aspect of the invention relates to a vehicle combination comprising a control unit according to the fourth aspect of the invention.

[0037] Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Embodiments of the invention cited as examples will be described in more detail hereinafter with reference to the accompanying drawings.

[0039] In the attached picture:

[0040] Figure 1 is a schematic top view of the vehicle combination;

[0041] Figure 2 Is a flowchart showing an embodiment of the method of the present invention;

[0042] Figure 3 is a diagram related to an embodiment of the present invention;

[0043] Figure 4 is a diagram related to another embodiment of the present invention, and

[0044] Figure 5 is a diagram showing the load envelope for a vehicle combination. DETAILED DESCRIPTION

[0045] Figure 1 An exemplary vehicle combination 10 of the type contemplated by the present disclosure is shown.

[0046] from Figure 1 As can be seen, the vehicle combination 10 includes a tractor 12 and a trailer 14. The tractor 12 includes a set of tractor wheels 16, 18, 20, 22, and the trailer includes a set of trailer wheels 26, 28, 32, 34. Figure 1In the embodiment of the vehicle combination 10 of FIG. 1 , the set of tractor wheels 16, 18, 20, 22 includes four wheels, and the set of trailer wheels 26, 28, 32, 34 includes six wheels. However, it is certainly contemplated that in various embodiments of the vehicle combination 10, each of the set of tractor wheels and the set of trailer wheels may include any number of wheels.

[0047] In addition, if Figure 1 As indicated, the tractor 12 includes a set of tractor motion support devices 36, 38, 40, 42 including at least one tractor motion support device, the set of tractor motion support devices being connectable to the set of tractor wheels 16, 18, 20, 22 and adapted to provide at least a tractor force. The tractor force is at least one of a tractor propulsion force and a tractor braking force. Figure 1 In the embodiment of the vehicle combination, the set of tractor motion support devices 36, 38, 40, 42 comprises two electric motors 36, 38, each connected to a dedicated wheel 16, 20. However, the set of tractor motion support devices 36, 38 may also or alternatively comprise an internal combustion engine (not shown). Furthermore, in embodiments of the vehicle combination, a single motor, engine or other type of propulsion device may be connected to one or more wheels via, for example, an axle or axle. Although Figure 1 The embodiment of the tractor 12 in the drawings includes two electric motors 36, 38, each connected to a dedicated front wheel 16, 20, but it is also contemplated that other embodiments of the tractor 12 may include one or more propulsion units (not shown) connected to the rear wheels 18, 22 of the tractor 12.

[0048] In addition, Figure 1 In an embodiment of the present invention, the set of tractor motion support devices 36, 38, 40, 42 includes service brakes 40, 42, each of which is connected to a dedicated wheel 18, 22. In addition, other embodiments of the tractor 12 may include service brakes arranged at wheels that are also connected to a propulsion unit (such as one of the electric motors 36, 38 described above).

[0049] It should be noted that Figure 1 The embodiment of the tractor 12 and the set of tractor motion support devices 36 , 38 , 40 , 42 shown in is merely an example, and other embodiments of the tractor 12 may have other configurations of the set of tractor motion support devices 36 , 38 , 40 , 42 .

[0050] In addition, if Figure 1As indicated, the trailer comprises a set of trailer motion support devices 44, 46, 48 including at least one trailer motion support device, the set of trailer motion support devices being connectable to the set of trailer wheels 26, 28, 32, 34 and adapted to provide at least a trailer force. The trailer force is at least one of a trailer propulsion force and a trailer braking force. Figure 1 The illustrated embodiment of the set of trailer movement support devices 44 , 46 , 48 comprises a propulsion device 44 , which can be embodied, for example, as an electric motor or an internal combustion engine, which is connected to two wheels via an axle 50 . Figure 1 The illustrated embodiment of the set of trailer motion support devices 44, 46, 48 comprises a service brake 46, 48, each service brake being connected to a dedicated wheel 28, 24. In the embodiment of the trailer 14, each wheel axle, and possibly each wheel, is connected to a service brake.

[0051] It should be noted that Figure 1 The embodiment of the trailer 14 and the set of trailer movement support devices 44 , 46 , 48 shown in is merely an example, and other embodiments of the trailer 14 may have other configurations of the set of trailer movement support devices 44 , 46 , 48 .

[0052] In addition, if Figure 1 As shown, the tractor 12 has a longitudinal direction L of the tractor. TR The tractor longitudinally extends along the tractor transverse direction T TR The tractor extends transversely and along the vertical direction V of the tractor TR The tractor extends vertically. The longitudinal direction of the tractor L TR Corresponds to the expected driving direction of the tractor 12 when the vehicle combination 10 is driving straight forward. TR Corresponding to the normal direction of the plane surface supporting the tractor 12, and the tractor transverse direction T TR Perpendicular to the longitudinal direction L of the tractor TR and the tractor vertical direction V TR Each one of them.

[0053] Similarly, the trailer 14 has a longitudinal direction L of the trailer. TL The longitudinal extension of the trailer and the transverse direction of the trailer T TL The trailer's transverse extension and the trailer's vertical direction V TL The trailer extends vertically. The longitudinal direction of the trailer L TL Corresponds to the expected driving direction of the trailer 14 when the vehicle combination 10 is traveling in a straight line. TL corresponds to the normal direction of the plane surface supporting the trailer 14, and the trailer transverse direction T TL Perpendicular to the trailer's longitudinal direction L TLand the trailer vertical direction V TL Each one of them.

[0054] Furthermore, the tractor 12 and trailer 14 are generally and as Figure 1 The tractor 10 and the tractor 11 are shown pivotably connected to each other at a pivot point 52. By way of example only, such a pivot point 52 can be implemented by a so-called fifth wheel. TR and the trailer longitudinal direction L TL There may be an articulation angle φ between them.

[0055] also, Figure 1 The vehicle combination is shown to include a control unit 54 for controlling the vehicle combination 10. Figure 1 In the embodiment of the invention, the control unit 54 is located in the tractor 12, but the control unit 54 may also be located in other locations, such as in the trailer 14. The control unit 54 is adapted to communicate with the set of tractor movement support devices 36, 38, 40, 42 and the set of trailer movement support devices 44, 46, 48 to control the operation of the vehicle combination 10. To this end, the control unit 54 may be connected to the set of tractor movement support devices 36, 38, 40, 42 and the set of trailer movement support devices 44, 46, 48 via wires (not shown), via a CAN bus system (not shown), via Ethernet, via a wireless system (not shown) or a combination of any of the above possibilities.

[0056] The present invention will be described below in conjunction with a method for controlling a vehicle combination 10. However, it should be noted that the following information also applies to the control unit 54 described above.

[0057] Thus, the present invention relates to a method for controlling a vehicle combination 10. As mentioned above, the vehicle combination 10 comprises a tractor 12 and a trailer 14. The tractor 12 comprises a set of tractor wheels 16, 18, 20, 22, and the trailer comprises a set of trailer wheels 26, 28, 32, 34. The tractor comprises a set of tractor motion support devices 36, 38, 40, 42 comprising at least one tractor motion support device, the set of tractor motion support devices being connectable to the set of tractor wheels 16, 18, 20, 22 and being adapted to provide at least a tractor force. The tractor force is at least one of a tractor propulsion force and a tractor braking force. The trailer comprises a set of trailer motion support devices 44, 46, 48 comprising at least one trailer motion support device, the set of trailer motion support devices being connectable to the set of trailer wheels 26, 28, 32, 34 and being adapted to provide at least a trailer force. The trailer force is at least one of a trailer propulsion force and a trailer braking force.

[0058] refer to Figure 2, the method comprising:

[0059] A request is received that a desired force exerted on the vehicle combination 10 should be provided by a set of motion support devices of a unique dedicated unit of the vehicle combination, which is a tractor or trailer (S10). As non-limiting examples, such a request may be issued by an operator, for example using an actuation device such as a joystick, a knob or a touch screen (not shown), or by an autonomous driving system (not shown).

[0060] By way of example only, such a request may be implemented by one of the following:

[0061] − Applying the desired braking force to the vehicle combination 10 solely by means of the set of motion supporting devices of the tractor vehicle 12. Such an implementation may be desirable, for example, when regenerative braking of the tractor vehicle 12 is employed in order to charge one or more electrical energy storage devices (not shown) of the tractor vehicle.

[0062] − The desired propulsion force is applied to the vehicle combination 10 only by the set of motion support devices of the trailer 14. Such an embodiment may be necessary, for example, when the energy storage devices associated with the set of tractor motion support devices 36, 38, 40, 42 have a small amount of energy.

[0063] − The desired braking force is applied to the vehicle combination 10 only by the set of motion supporting devices of the trailer. Such an implementation may be desirable, for example, when regenerative braking of the trailer 14 is employed in order to charge one or more electrical energy storage devices (not shown) of the trailer.

[0064] − The desired propulsion force is applied to the vehicle combination 10 only by the set of motion support devices of the tractor 14. Such an embodiment may be necessary, for example, when the energy storage device associated with the set of trailer motion support devices 46, 48, 50 has a small amount of energy.

[0065] Regardless of which unique dedicated unit is selected and the reason for selecting the unique dedicated unit, the method further comprises:

[0066] When it is determined that the set of motion support devices of the unique dedicated unit is capable of providing the desired force applied to the vehicle combination when each safety requirement in a predetermined set of safety requirements of the vehicle combination is met (S12), only the set of motion support devices of the unique dedicated unit is operated to provide the desired force (S14), otherwise one or more of the tractor motion support devices and one or more of the trailer motion support devices are operated to provide the desired force applied to the vehicle combination (S16), wherein the predetermined set of safety requirements includes at least one safety requirement.

[0067] In general, it should be noted that upon determining that the set of motion support devices of the unique dedicated unit cannot provide the desired force to be applied to the vehicle combination when each of the predetermined set of safety requirements of the vehicle combination is met, the method preferably includes operating the set of motion support devices of the unique dedicated unit so as to provide a reduced force having an absolute value that is smaller than the absolute value of the desired force. Preferably, such reduced force is determined by determining the force with the maximum absolute value that the set of motion support devices of the unique dedicated unit can provide when each of the predetermined set of safety requirements of the vehicle combination is met. The remaining load (i.e. the difference between the desired force and the reduced force) can then be provided by the set of motion support devices of the tractor 12 or trailer 14 that is not the unique dedicated unit.

[0068] However, it is also conceivable that in an embodiment of the method of the present invention, it is determined that the set of motion support devices of the unique dedicated unit cannot provide the desired force applied to the vehicle combination when each of the predetermined set of safety requirements of the vehicle combination is met, and the method may include determining a predetermined force distribution of the forces provided by the set of motion support devices of the tractor 12 and the trailer 14 so as to achieve the desired force.

[0069] Various implementations of the security requirements are described below.

[0070] In a first embodiment, the predetermined set of safety requirements of the vehicle combination comprises a lateral acceleration safety condition requiring that for each of the set of motion support devices of the unique dedicated unit, the longitudinal force F generated by the motion support device x must be equal to or below a longitudinal force limit value determined by a longitudinal force limit function which is a function of at least the lateral acceleration ay of the unique dedicated unit.

[0071] Lateral acceleration a y Extending in the transverse direction of the unique dedicated unit, that is, in the transverse direction of the tractor 12, the tractor TR , and for the trailer 14, the trailer transverse direction T TL The lateral acceleration a may be measured using an acceleration sensor (not shown) located in a unique dedicated unit (i.e., tractor 12 or trailer 14). y .

[0072] Longitudinal force F x It can be propulsion or braking force.

[0073] For example only, the longitudinal force limit function may be the lateral acceleration a using the unique dedicated unit y A proportional value is taken as input and provides the normalized longitudinal force F x / µF z As a function of the proportional value of the output, the normalized longitudinal force is the longitudinal force F x divided by the total vertical load F applied to the wheel or wheels connected to the motion support device z and a friction value µ indicative of the friction between one or more wheels connected to the motion support device and the ground supporting the unique dedicated unit.

[0074] Furthermore, but again only by way of example, the longitudinal force limit function uses the lateral acceleration a of the unique dedicated unit y Dividing by a friction reference value µg as input, the friction reference value being a friction value µ indicative of the friction between the set of wheels of the unique dedicated unit and the ground supporting the unique dedicated unit multiplied by an acceleration value g corresponding to the acceleration due to gravity.

[0075] refer to Figure 3 , the longitudinal force limit function can be a step function, such that:

[0076] − When the lateral acceleration a of the unique dedicated unit y The value obtained by dividing the friction reference value µg is less than or equal to a predetermined threshold value (the threshold value is Figure 3 The output is set to a fixed non-zero value of the normalized longitudinal force when the value of

[0077] − When the lateral acceleration of the unique dedicated unit divided by the friction reference value has a value greater than the predetermined threshold as input, the output is set to zero.

[0078] It should be noted that the longitudinal force limit function does not have to be a step function. Figure 4 , which shows an implementation in which the longitudinal force limit function is a continuous function.

[0079] Regardless of how the longitudinal force limit function is implemented, a longitudinal force limit value may be determined for each motion support device of a unique dedicated unit, for example according to the following procedure.

[0080] The lateral acceleration a of a unique dedicated unit (i.e., tractor 12 or trailer 14) can be determined y Such a lateral acceleration value a can be determined, for example, using an accelerometer (not shown). y. In addition, a value of a friction value μ indicative of the friction between the one or more wheels connected to the motion support device and the ground supporting the unique dedicated unit may be determined. Such a friction value μ may be determined using any known procedure, such as using a sensor (such as a camera) to monitor the condition of the ground on which the unique dedicated unit is traveling and / or by using a brush model or using slip values ​​associated with one or more wheels. In addition, the total vertical load currently applied to the one or more wheels connected to the motion support device is determined, for example using information available from one or more suspension devices connected to the one or more wheels.

[0081] Lateral acceleration value a y and the friction value µ can be used as input to the longitudinal force limit function, e.g. as described above in reference Figure 3 or Figure 4 As shown, in order to obtain the standardized longitudinal force F x / µF z Then, the normalized longitudinal force F x / µF z Multiply the friction value µ and the total vertical load F currently applied to the wheel or wheels connected to the kinematic support device z To determine the longitudinal force limit F x .

[0082] The above procedure may be performed for each motion support device of a unique dedicated unit (ie, tractor 12 or trailer 14), and the longitudinal force limit value F may thereafter be calculated. x The summation is performed to arrive at a total longitudinal force limit value associated with the unique dedicated unit.

[0083] As an alternative or in addition to the above-mentioned lateral acceleration safety condition, the predetermined set of safety requirements for the vehicle combination may include a longitudinal slip safety condition, which requires that the detected longitudinal slip value for at least a selected subset of the set of wheels of the unique dedicated unit is below a predetermined threshold. Therefore, the unique dedicated unit (i.e., the tractor 12 or the trailer 14) can be equipped with a device for determining the longitudinal slip value of at least a selected subset of the set of wheels associated with the unique dedicated unit. Thereafter, each determined longitudinal slip value can be compared with a predetermined threshold to ensure that any of the selected subset of the set of wheels does not slip excessively. In response to verifying that excessive slip does not occur, the longitudinal slip safety condition can be deemed to have been met or achieved.

[0084] As an alternative to or in addition to the above-mentioned safety conditions, the predetermined set of safety requirements for the vehicle combination may include a state determination condition, which requires that for a predetermined vehicle state, the difference between a vehicle state measurement value associated with a measurement value indicating the predetermined vehicle state and a vehicle state expected value associated with an expected value indicating the predetermined vehicle state is within a predetermined state range.

[0085] Merely as an example, the expected value of the vehicle state may be determined using a vehicle model of the vehicle combination, preferably a vehicle model and a tire model of the set of tractor wheels and / or the set of trailer wheels.

[0086] For example, the predetermined vehicle state is the yaw rate of the unique dedicated unit. The yaw rate is generally associated with the rotation speed about an axis of the unique dedicated unit extending in the vertical direction.

[0087] As another non-limiting example, the predetermined vehicle state may be the articulation angle φ (described above with reference to Figure 1 The articulation angle φ is presented, or the rate of change of the articulation angle between the tractor 12 and the trailer 14 .

[0088] Furthermore, the predetermined vehicle state may be a sideslip angle of the unique dedicated unit.

[0089] Furthermore, the predetermined vehicle state may be a sideslip angle for at least a selected subset of the set of wheels of the unique dedicated unit.

[0090] It should be noted that embodiments of the method according to the present invention may employ combinations of the state determination conditions exemplified above.

[0091] As mentioned above, the desired force exerted on the vehicle may be a propulsion force or a braking force.

[0092] It should also be noted that the present invention is not limited to a vehicle combination 10 comprising a tractor and a single trailer. Therefore, in an embodiment of the method, the vehicle combination comprises one or more additional trailers, each additional trailer comprising a set of additional trailer motion support devices including at least one additional trailer motion support device, the set of additional trailer motion support devices being connectable to the set of additional trailer wheels and being adapted to provide at least an additional trailer force, the additional trailer force being at least one of an additional trailer propulsion force and an additional trailer braking force.

[0093] The method comprises:

[0094] − receiving a request that a desired force exerted on said vehicle combination should be provided by said set of motion support devices of a unique dedicated unit of said vehicle combination, said unique dedicated unit being one of said one or more additional trailers, said tractor vehicle or said trailer;

[0095] − upon determining that the set of motion support devices of the unique dedicated unit are capable of providing a desired force to be exerted on the vehicle combination when each of a predetermined set of safety requirements of the vehicle combination is met, only operating the set of motion support devices of the unique dedicated unit so as to provide the desired force, otherwise operating one or more of the tractor motion support devices and one or more of the trailer motion support devices and / or one or more of the additional trailer motion support devices of one or more of the one or more additional trailers so as to provide the desired force to be exerted on the vehicle combination, wherein the predetermined set of safety requirements includes at least one safety requirement.

[0096] at last, Figure 5 A force envelope 56 for a vehicle combination 10 including a first motion support device and a second motion support device is shown. For each motion support device, Figure 5 The force envelope presents the normalized longitudinal force F as discussed above. x,1 / µF z,1 or F x,2 / µF z,2 The limit is the lateral acceleration a of the relevant unit (ie, the tractor 12 or the trailer 14). y Divide by the above friction reference value µg function.

[0097] from Figure 5 It can be seen that the envelope can be used to determine the maximum combined longitudinal load that the first motion support device and the second motion support device can provide while satisfying each of a predetermined set of safety requirements for the vehicle combination. Figure 5 The envelope of may be used to identify one or more suitable pairs of longitudinal forces provided by the first motion support device and the second motion support device.

[0098] There is no doubt that Figure 5 The envelope of may be extended to include a plurality of kinematic supports greater than two, such that an envelope is created for each kinematic support in the vehicle combination 10 .

[0099] In addition, the longitudinal force limit value of each motion support device of the tractor 12 can be aggregated to obtain the longitudinal force limit value of the longitudinal force that can currently be generated by all the motion support devices of the tractor 12. Similarly, the longitudinal force limit value of each motion support device of the trailer 14 can be aggregated to obtain the longitudinal force limit value of the longitudinal force that can currently be generated by all the motion support devices of the trailer 14.

[0100] Thereafter, the longitudinal force limit values ​​of all motion support devices of the tractor and trailer, respectively, may be used in order to determine a suitable combination of longitudinal forces to be provided by the tractor 12 and trailer 14 .

[0101] It should be understood that the present invention is not limited to the embodiments described above and shown in the drawings; rather, those skilled in the art will recognize that many changes and modifications are possible within the scope of the appended claims.

Claims

1. A method for controlling a vehicle combination (10), the vehicle combination (10) comprising a tractor (12) and a trailer (14), the tractor (12) comprising a set of tractor wheels (16, 18, 20, 22), and the trailer (14) comprising a set of trailer wheels (26, 28, 32, 34), the tractor (12) comprising a set of tractor motion support devices (36, 38, 40, 42) including at least one tractor motion support device, the set of tractor motion support devices being connectable to the set of tractor wheels (16, 18, 20, 22) and being adapted to provide at least a tractor force, the tractor force being at least one of a tractor propulsion force and a tractor braking force, and the trailer (14) comprising a set of trailer motion support devices (44, 46, 48) including at least one trailer motion support device, the set of trailer motion support devices being connectable to the set of trailer wheels (26, 28, 32, 34), thereby being suitable for providing at least a trailer force, the trailer force being at least one of a trailer propulsion force and a trailer braking force, the method comprising: − receiving a request that a desired force exerted on the vehicle combination (10) should be provided by a set of motion support devices of a unique dedicated unit of the vehicle combination (10), the unique dedicated unit being the tractor (12) or the trailer (14); − when it is determined that the set of motion support devices of the unique dedicated unit is capable of providing the desired force applied to the vehicle combination (10) when each safety requirement in a predetermined set of safety requirements of the vehicle combination (10) is met, only the set of motion support devices of the unique dedicated unit is operated to provide the desired force, otherwise one or more of the tractor (12) motion support devices and one or more of the trailer (14) motion support devices are operated to provide the desired force applied to the vehicle combination (10), wherein the predetermined set of safety requirements includes at least one safety requirement.

2. The method according to claim 1, wherein the predetermined set of safety requirements of the vehicle combination (10) includes a lateral acceleration safety condition requiring that, for each of the set of motion support devices of the unique dedicated unit, the longitudinal force (F x ) must be equal to or lower than a longitudinal force limit value determined by a longitudinal force limit function, the longitudinal force limit function being a function of at least the lateral acceleration (a) of the unique dedicated unit. y ) function.

3. The method of claim 2, wherein the longitudinal force limit function is a function of the lateral acceleration (a) of the unique dedicated unit. y ) as input and provides a value proportional to the normalized longitudinal force (F x / µF z ) is a proportional value as a function of the output, the standardized longitudinal force is the longitudinal force (F x ) divided by the total vertical load (F) applied to the wheel or wheels connected to the motion support device z ) and a friction value (µ) indicative of the friction between the one or more wheels connected to the motion support device and the ground supporting the unique dedicated unit.

4. The method of claim 3, wherein the longitudinal force limit function uses the lateral acceleration (a) of the unique dedicated unit. y ) divided by a friction reference value (µg) as input, wherein the friction reference value is a friction value (µ) indicating the friction between a set of wheels of the unique dedicated unit and the ground supporting the unique dedicated unit multiplied by an acceleration value (g) corresponding to the acceleration due to gravity.

5. The method according to claim 4, wherein the longitudinal force limit function is a step function such that: − When the lateral acceleration (a y ) divided by the friction reference value (µg) to obtain a value less than or equal to a predetermined threshold as input, the output is set to the standardized longitudinal force (F x / µF z ), and − When the lateral acceleration (a y ) divided by the friction reference value (µg) is taken as input, and the output is set to zero.

6. A method according to any one of the preceding claims, wherein the predetermined set of safety requirements for the vehicle combination (10) includes a longitudinal slip safety condition, which requires that the detected longitudinal slip value of at least a selected subset of the set of wheels of the unique dedicated unit is below a predetermined threshold.

7. A method according to any one of the preceding claims, wherein the predetermined set of safety requirements for the vehicle combination (10) includes a state determination condition, which requires that for a predetermined vehicle state, the difference between a vehicle state measurement value associated with a measurement value indicating the predetermined vehicle state and a vehicle state expected value associated with an expected value indicating the predetermined vehicle state is within a predetermined state range.

8. The method according to claim 7, wherein the expected value of the vehicle state is determined using a vehicle model of the vehicle combination (10), preferably, the expected value of the vehicle state is determined using a vehicle model and a tire model of the set of tractor wheels (16, 18, 20, 22) and / or the set of trailer wheels (24, 26, 28, 30, 32, 34).

9. A method according to claim 7 or 8, wherein the predetermined vehicle state is the yaw rate of the unique dedicated unit.

10. The method according to any one of claims 7 to 9, wherein the predetermined vehicle state is an articulation angle (φ) or an articulation angle change rate (φ) between the tractor (12) and the trailer (14). ).

11. A method according to any one of claims 7 to 10, wherein the predetermined vehicle state is the sideslip angle of the unique dedicated unit.

12. A method according to any one of claims 7 to 11, wherein the predetermined vehicle state is a sideslip angle for at least a selected subset of the set of wheels of the unique dedicated unit.

13. A method according to any preceding claim, wherein the desired force exerted on the vehicle is a propulsive force.

14. A method according to any one of claims 1 to 12, wherein the desired force applied to the vehicle is a braking force.

15. A method according to any one of the preceding claims, wherein the vehicle combination (10) comprises one or more additional trailers (14), each additional trailer (14) comprising a set of additional trailer (14) motion support devices including at least one additional trailer (14) motion support device, the set of additional trailer (14) motion support devices being connectable to the set of additional trailer (14) wheels so as to be suitable for providing at least an additional trailer (14) force, the additional trailer (14) force being at least one of an additional trailer (14) propulsion force and an additional trailer (14) braking force, the method comprising: − receiving a request that a desired force exerted on the vehicle combination (10) should be provided by a set of motion support devices of a unique dedicated unit of the vehicle combination (10), the unique dedicated unit being one of the one or more additional trailers (14), the tractor (12) or the trailer (14); − when it is determined that the set of motion support devices of the unique dedicated unit is capable of providing the desired force to be applied to the vehicle combination (10) when each of a predetermined set of safety requirements of the vehicle combination (10) is met, only the set of motion support devices of the unique dedicated unit is operated so as to provide the desired force, otherwise one or more of the tractor (12) motion support devices and one or more of the trailer (14) motion support devices and / or one or more of the additional trailer (14) motion support devices of one or more of the one or more additional trailers (14) are operated so as to provide the desired force to be applied to the vehicle combination (10), wherein the predetermined set of safety requirements includes at least one safety requirement.

16. A computer program comprising program code means for performing the steps of any of the preceding claims when said program is run on a computer.

17. A computer readable medium carrying a computer program, the computer program comprising program code means for executing the steps of any one of claims 1 to 15 when the program product is run on a computer.

18. A control unit for controlling a vehicle, the control unit being configured to perform the steps of the method according to any one of claims 1 to 15.

19. A vehicle combination (10) comprising a control unit according to claim 18.

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