Improved startability of a heavy vehicle under split-MU conditions

Abstract

A computer system (500) for a heavy vehicle equipped with an active suspension (552) is provided, including processing circuitry (510) configured to obtain an indication (522) of a desire to start the vehicle from a standstill; obtain an indication (530) of a surface friction on a first side of a driven axle of the vehicle being lower than a surface friction on an opposite, second side of the driven axle; obtain an indication whether a differential (542) of the driven axle is currently open or locked; in response to the differential being, control (550) the active suspension to increase a loading on the first side of the driven axle, and, in response to the differential being locked, control the active suspension to increase a loading on the second side of the driven axle. A corresponding vehicle, computer-implemented method, computer program product and computer-readable storage medium are also provided.

Description

IMPROVED STARTABILITY OF A HEAVY VEHICLE UNDER SPLIT- MU CONDITIONSTECHNICAL FIELD

[0001] The disclosure relates generally to the field of heavy vehicles having height adjustable suspension. In particular aspects, the disclosure relates to handling (such as starting) of such vehicles under so-called split-mu conditions, wherein a road friction coefficient between each wheel and ground is not equal for all wheels. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, such as a bus, the disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] So-called split-mu conditions arise when all wheels of a vehicle do not experience the same road conditions. For example, the vehicle may be on a stretch of road wherein e.g. half a lane is covered with ice or snow, but wherein the other half of the lane has exposed patches of tarmac, gravel or similar. As a consequence, the friction coefficients (mu’s, or / Us) between the respective wheels and ground will thus not all be equal.

[0003] If the vehicle is equipped with a differential, split-mu conditions may make handling of the vehicle particularly challenging, especially when attempting to e.g. start the vehicle from standstill. For example, if the differential is open, more of the power will be transferred to the wheel where the friction coefficient is lowest, resulting in this wheel spinning and a loss of efficiency as the vehicle will gain no or little speed compared to when driving on a surface with even friction across the whole lane. If the differential is instead locked, the traction force may be limited by the available normal load on the comer / wheel that is currently on the higher-friction surface.

[0004] The present disclosure aims at facilitating the handling (such as starting) of the vehicle under split-mu conditions.SUMMARY

[0005] According to a first aspect of the present disclosure, there is provided a computer system for a heavy vehicle equipped with an active suspension. The computer systemincludes processing circuitry configured to: obtain an indication of a desire to start the vehicle from a standstill (or e.g. increase a speed of the vehicle from a low speed, such as from almost standstill); obtain an indication of a surface friction on a first side of a driven axle of the vehicle being lower than a surface friction on an opposite, second side of the driven axle (wherein the surface friction is for a surface on which the vehicle is standing / located); obtain an indication of whether a differential of the driven axle is open or locked; in response to the differential being open, control the active suspension to increase a loading on the first side of the driven axle, and, in response to the differential being open, control the active suspension to increase a loading on the second side of the driven axle. The first aspect of the present disclosure may seek to improve the handling (i.e. startability) of the vehicle under split-mu conditions. A technical benefit may include that by shifting load to a particular side of the driven axle of the vehicle taking the state of the differential into account, the shifting of load can be performed such that traction of the driven axle is improved, thereby making starting of the vehicle under the split-mu conditions more manageable and effective.

[0006] Optionally in some examples, including in at least one preferred example, the processing circuitry may be further configured to: in response to the differential being open, control the active suspension to decrease a loading on the second side of the driven axle, and, in response to the differential being locked, control the active suspension to decrease a loading on the first side of the driven axle. A technical benefit may include that by adjusting the loading on both sides of the driven axle, the startability may be further improved by further increasing the overall traction of the driven axle.

[0007] Optionally in some examples, including in at least one preferred example, increasing the loading on the first or second side of the driven axle may include to control the active suspension to move a center-of-gravity (COG) of the vehicle. A technical benefit may include that the COG may be positioned such that the overall traction of the driven axle, taking the state of the differential into account, may be improved.

[0008] Optionally, in some examples, including in at least one preferred example, increasing the loading on the first or second side of the driven axle may include to control the active suspension to increase the loading by one or more forces on the driven axle induced by a torsional stiffness of a chassis of the vehicle. A technical effect may include that the chassis may be used to create the desired forces on the respective side of the driven axle, without necessarily having to move the vehicle’s COG.

[0009] Optionally, in some examples, including in at least one preferred example, increasing the loading on the first or second side of the driven axle may include to request different roll angles from front and rear axle groups of the vehicle. As mentioned above, a technical benefit may include that he forces on the respective side of the driven axle can be obtained without necessarily, or in addition to, moving the COG of the vehicle.

[0010] Optionally, in some examples, including in at least one preferred example, the processing circuitry may be further configured to control the active suspension based on (physical) model of the vehicle. A technical benefit may include that a trial-and-error procedure wherein the active suspension is controlled until a desired configuration is obtained may be avoided, and energy may thus be spent more wisely or not at all. This as by using the model of the vehicle, a desired wheel height level configuration may be determined in advance in order to obtain a desired resulting force distribution on the vehicle’s wheels (especially on the wheels of the driven axle), and the various wheel level heights can then be obtained directly without preceding trial-and-error.

[0011] Optionally, in some examples, including in at least one preferred example, the model may include a mapped knowledge of load shifts for different combinations of roll angles requested from front and rear axle groups of the vehicle. This may be particularly useful if the stiffness of the vehicle chassis is used to induce the various (normal / vertical) forces on the wheels.

[0012] Optionally, in some examples, including in at least one preferred example, the physical model may include a model-based algorithm for the vehicle. A technical benefit may include that the need to map knowledge by e.g. one or more experiments can be avoided, and / or that such a model-based algorithm may complement a model obtained based on such experiments, and similar.

[0013] Optionally, in some examples, including in at least one preferred example, the processing circuitry may be further configured to obtain suspension capability information pertinent to a current capability of the active suspension of the vehicle, and to control the active suspension also based on the suspension capability information. A technical benefit of taking the capabilities of the suspension into account may include that a more energy efficient solutions is obtained, and / or that solutions that are theoretically but not practically possible are avoided completely or at least more often. The suspension capability information may e.g. include information about possible load transfers that may be achieved by the activesuspension as currently configured. The suspension capability information may e.g. indicate that one or more actuators of the active suspension is currently not offering their full potential (due to e.g. being fully or partially damaged), and the computer system may take this into account when deciding how to operate the active suspension to achieve the load transfers.

[0014] Optionally, in some examples, including in at least one preferred example, the processing circuitry may be further configured to both obtain the suspension capability information and control the active suspension of the vehicle via a same suspension control / capability interface. A technical benefit may include that the computer system can be made agnostic to the exact configuration of the active suspension, and include all information required via the interface only. For example, the computer system may thus not be required to have any hardcoded data about e.g. various types of suspension actuators, their capabilities, etc. programmed into its memory, but may receive any such information (as needed) from the interface. Likewise, the computer system may not need to be explicitly configured to communicate with a particular actuator or control system of the active suspension, but both the control and readout of capabilities may instead be performed via the interface which may be standardized such that how to communicate with the interface does not depend on the exact configuration of the active suspension.

[0015] According to a second aspect of the present disclosure, there is provided a heavy vehicle. The vehicle includes an active suspension, at least one driven axle, and the computer system of the first aspect (or any examples thereof disclosed herein).

[0016] Optionally, in some examples, including in at least one preferred example, of the vehicle, the active suspension may be a gas-hydraulic suspension and / or pneumatic suspension. In other examples, other types of active suspension are also envisaged as suitable for the solution of the present disclosure

[0017] According to a third aspect of the present disclosure, there is provided a computer- implemented method for improving startability of a heavy vehicle having an active suspension. The method includes obtaining, by processing circuitry of a computer system (such as the computer system of the first aspect or embodiments thereof described herein), an indication of a desire to start the vehicle from a standstill (or e.g. from almost standstill); obtaining an indication of a surface friction on a first side of a driven axle of the vehicle being lower than a surface friction on an opposite, second side of the driven axle; obtaining an indication of whether a differential of the driven axle is open or locked, and, controllingthe active suspension to increase a loading on either the first side of the driven axle or on the second side of the driven axle, depending on whether the differential is open or locked.

[0018] Optionally, in some examples, including in at least one preferred example, of the method, controlling the active suspension may include to increase a loading on the first side of the driven axle in response to the differential being open.

[0019] Optionally, in some examples, including in at least one preferred example, of the method, controlling the active suspension may include to increase a loading on the second side of the driven axle in response to the differential being locked.

[0020] Optionally, in some examples, including in at least one preferred example, of the method, controlling the active suspension may include to decrease a loading on the second side of the driven axle in response to the differential being open.

[0021] Optionally, in some examples, including in at least one preferred example, of the method, controlling the active suspension may include to decrease a loading on the first side of the driven axle in response to the differential being locked.

[0022] According to a fourth aspect of the present disclosure, there is provided a computer program product including program code (e.g. instructions) for performing, when executed by a processing circuitry of a computer system (such as the computer system of the first aspect or embodiments thereof described herein), the method of the third aspect (or any examples thereof disclosed herein).

[0023] According to a fifth aspect of the present disclosure, there is provided a non- transitory computer-readable storage medium comprising instructions, which when executed by a processing circuitry of a computer system (such as the computer system of the first aspect or examples thereof described herein), cause the processing circuitry to perform the method of the third aspect (or any examples thereof described herein).

[0024] The disclosed aspects, examples (including any preferred examples), and / or accompanying claims may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art. Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein.

[0025] There are also disclosed herein computer systems, control units, code modules, computer-implemented methods, computer readable media, and computer program products associated with the above discussed technical benefits.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Examples are described in more detail below with reference to the appended drawings.

[0027] FIGS. 1A and IB schematically illustrate an exemplary vehicle, in form of a bus, equipped with an active suspension, according to an example.

[0028] FIG. 2 schematically illustrates a flowchart of an exemplary method according to an example.

[0029] FIG. 3 schematically illustrates a setup of an exemplary experiment performed to validate the proposed solution.

[0030] FIG. 4 schematically illustrates a diagram of an exemplary computer system for implementing examples disclosed herein, according to an example.

[0031] FIGS. 5A and 5B schematically illustrate exemplary computer systems for implementing examples disclosed herein, according to an example.DETAILED DESCRIPTION

[0032] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0033] Figs. 1A and IB schematically illustrates an exemplary heavy vehicle 100 according to an example, in form of a bus. This particular vehicle 100 has a first (wheel) axle 110 and a second (wheel) axle 120. The first axle 110 includes a transverse pair of wheel units 112 and 114, and the second axle 120 includes a transverse par of wheel units 122 and 124. Herein, a “wheel unit” may be a single wheel, a set of dual wheels, a set of triple wheels, or similar. A “transverse pair of wheels” includes two wheels mounted on or arranged at opposite sides of the axle. In the particular example illustrated in Figs. 1 A and IB, the wheel units 112 and 114 of the first axle 110 are each single wheels, while the wheel units 122 and 124 of the second axle 120 are each dual wheels (i.e. a combination of two single wheels side by side). In the particular example of the vehicle 100, the first axle 110 is a steerable front axle of the vehicle 100, and the second axel 120 is a driven rear axle of the vehicle 100. It should be noted that herein, when referring to two wheel units being associated with, mounted on, arranged on or at, e.g., a particular “axle”, it is not necessarily so that the twowheel units are physically linked by a physical axle. For example, the steerable front axle 110 may not be a driven axle, and there may be no physical axle connecting the two wheel units 112 and 114, and similar. Thus, it is assumed that as a minimum, an axle is a representation of a pair of transverse wheel units that may or may not be physically linked / connected by a same physical axle, such as e.g. a drive shaft or similar. For example, in a driven axle utilizing a differential, the wheel units on each side of the axle may not necessarily be connected via a single shaft or similar, but instead each be connected, via the differential, such that the wheel units may rotate independently of each other, at least in some configurations of the differential.

[0034] A vehicle as envisaged herein may be at least partially or fully electric, wherein one or more electrical machines are used to propel the vehicle. In other examples as envisaged herein, propulsion may instead by provided by one or more internal combustion engines (ICEs). In any case, it is envisaged that the vehicle has at least one driven axle, and that this axle includes, or is associated with, a differential which governs how much of a single propulsion torque / force that is provided to the differential that is then distributed to each wheel unit. The same applies for other types of propulsion systems such as hybridelectrics, fuel cells, and similar, which are also envisaged as possible alternatives for how the vehicle as envisaged herein is propelled.

[0035] The vehicle 100 is equipped with a differential 170 (not explicitly illustrated in FIGS. 1 A and IB, but instead indicated by the iconic symbol in FIG. IB) on the driven axle 120. The differential 170 is operable between at least an open state and a locked state. In the open state (i.e. when the differential is “open”, or “unlocked”), the differential 170 will allow the wheel units 122 and 124 to rotate independently of each other (i.e. with different rotational speeds), in order to e.g. prevent wheel hop, vehicle instability and excessive tire wear, especially when the vehicle is turning. In the open state, the differential 170 distributes power from a transmission / propulsion system 174 of the vehicle 100 such that more power is provided to the wheel unit having easier to rotate, i.e. to the wheel unit providing least traction. Consequently, if there is no friction between a particular wheel unit and the ground, e.g. as a consequence of the wheel unit being lifted from ground, that wheel unit will be rotated while the other wheel unit, in contact with the ground, will remain still and receive no propulsion torque / force.

[0036] In the locked stated (i.e. when the differential is “locked”), the differential 170 will not allow the wheel units 122 and 124 to rotate independently of each other, and both wheel units 122 and 124 will be required to rotate with a same rotational speed. When locked, the differential 170 thus provides an equal amount of power from the transmission / propulsion system 174 to each wheel unit 122 and 124, providing better traction capabilities on e.g. slippery surfaces or in a situation when one of the wheel units 122 and 124 are not in contact with the ground, as the other wheel unit would then still be allowed to propel the vehicle 100 forward / backward. As used herein, if the vehicle 100 were to have more than one driven axle, it is envisaged that “a differential” may include individual differentials for each driven axle, a central differential, or a combination of both a central differential (such as a “transfer case”) and differentials for / in each driven axle.

[0037] As used herein, that the differential 170 is operable between at least these two states includes that the differential is manually operable (e.g. by the driver interacting with a switch, lever or menu option on e.g. the dashboard 160s, in which case the differential 170 may also be referred to as a “selectable locker” or similar) between the two states, or that the differential 170 is automatically changed between the at least two states based on input from (or e.g. controlled by) some other functional entity of the vehicle 100, such as e.g. an automated driving system (ADS), advanced driver-assistance system (ADAS), or similar. As also envisaged herein, a differential may also be e.g. a so-called “automatic locker”, such as an automatic unlocking differential, an automatic locker operating as an open differential until e.g. wheel slip is encountered, or similar. In particular, it is envisaged herein that the proposed solution may include to check whether the differential is currently locked and, if not, control the differential (if possible) to its locked state, as this may improve traction due to the longitudinal force exerted on ground being highest on the higher-mu side with a locked differential compared to the lower-mu side with an open differential (for a same amount of load transfer). Phrased differently, the proposed solution may include to force the differential (if possible) to its locked state on purpose, and then of course include not doing any particular operation in case the differential is determined to be opened, other than forcing it to be locked.

[0038] The vehicle 100 is further equipped with an active suspension, that allows to individually control a distance between at least each wheel unit 122 and 124 and a chassis of the vehicle 100 in a vertical direction. The active suspension may also, as will be assumed inthis particular example, be capable of control such distances also for the wheel units 112 and 114 of / on the front axle 110. In this particular example, the active suspension includes a plurality of suspension cylinders, including a cylinder 130a for the wheel unit 112, a cylinder 130b for the wheel unit 114, two cylinders 130c for the wheel unit 122, and two cylinders 130d for the wheel unit 124. The cylinders 130a-d may be air springs (in case of a pneumatic suspension), air / hydraulic springs in case of gas-hydraulic suspension, and similar. For example, in case of a gas-hydraulic active suspension, each cylinder 130a-d may include a volume of a compressible gas (such as e.g. nitrogen) trapped between an upper part of the cylinder and a non-permeable (such as rubber) membrane. On the other side of the membrane, hydraulic fluid may be provided in order to cause actuation of the spring element in form of the compressible gas once force (from the wheel units) is exerted on the (non- compressible) hydraulic fluid. By adjusting the amount of hydraulic fluid in each cylinder, a leveling functionality may be implemented in which the distance between the vehicle chassis and each wheel unit in the vertical direction can be adjusted. In other examples, if the cylinders 130a-d are instead air-springs, the cylinders 130a-d may e.g. be bellows whose sizes may be adjusted depending on how much air that is currently provided in each bellow. Other examples are also envisaged, as long as these alternatives allow to adjust the distances as described above, at least individually on both sides of a driven axle of the vehicle.Although not illustrated in Figs. 1 A and IB, one or more (steel) springs may also be provided for each wheel, in addition to the cylinders 130a-d, if required. Independent on exactly how the active suspension is constructed and operates, it is envisaged herein that the active suspension is any suspension that allows the distance between the respective wheel unit (unsprung mass) and a chassis (sprung mass) of the vehicle 100 to be adjusted. Such active suspensions are commonly known and available to the skilled person.

[0039] In order to adjust the amount of air, hydraulic fluid, etc., in each cylinder 130a-d, the active suspension includes, in this example, a plurality of fluid channels 140 in which air, hydraulic fluid, etc., can be routed to and / or from each cylinder 130a-d. The active suspension further includes at least one reservoir 142 for storing the fluid not currently in any of the cylinders 130a-d, and also a plurality of control valves 144 for controlling how the fluid flows between the cylinders 130a-d and the reservoir 142. Although not shown, the active suspension may also include on or more pressure providing elements, such as a compressor, to provide sufficient fluid pressure in the active suspension system.

[0040] The active suspension may also include one or more level sensors 146a-d, e.g. a sensor 146a at the wheel unit 112, a sensor 146b at the wheel unit 114, a sensor 146c at the wheel unit 122, and a sensor 146d at the wheel unit 124. The sensors 146a-d may be configured to provide a signal indicative of the distance between the respective wheel unit and the chassis in the vertical direction. Such signals, as well as e.g. control signals to / from the fluid valves 144, are provided via a plurality of control and / or communication lines 148 to a control unit 150. The control unit 150 may also be referred to as, or at least include or be included as part of, a computer system 150, and is configured to e.g. control the active suspension to individually adjust the distance between each wheel unit 112, 114, 122, 124 and the chassis of the vehicle 100.

[0041] The computer system 150 may optionally also be communicatively coupled to one or more other systems of the vehicle 100 (via e.g. the plurality of control and / or communication lines 148), for example to one or more of a dashboard 160 of the vehicle 100, such that the computing system 150 may receive signals indicative of for example a driver pressing a particular button on the dashboard, selecting a particular menu option on a touch-sensitive display of the dashboard 160, and / or to display one or more messages to the driver via the dashboard 160; a steering wheel 162 of the vehicle 100, such that the computer system 150 may receive information about e.g. a turning angle and / or turning rate of the steering wheel 162; one or more actuation pedals 164 of the vehicle 100, such as e.g. one or more of a throttle pedal, clutch pedal, brake pedal, and similar, in order for the computing system 150 to know how / when the driver presses / releases such pedals, and similar.

[0042] The computer system 150 is communicatively coupled to the differential (or plurality of differentials) 170 in order to obtain an indication of a current state of the differential, or at least to some other entity capable of providing such information about the state of the differential 170. The computer system 150 may also be communicatively coupled to, and e.g. capable of controlling, a steering system 172 for providing assisted (servo) steering of the vehicle 100, and / or a transmission / propulsion system 174 of the vehicle 100 responsible for e.g. propelling and / or braking the vehicle 100. There may of course be separate systems responsible for the braking and propelling of the vehicle 100, respectively, and the computer system 150 may then of course be connected to one or both of such separate systems. In general, the control system 150 may include all required functionality in a same physical unit, or may e.g. be formed by a plurality of distributed units of the vehicle100. For example, there may be separate units responsible for a respective part of the overall functionality, such as controlling the valves 144, reading the sensors 146a-d, and / or to communicate with / control one or more other parts of the vehicle 100. In some examples, one, more or all such units required to perform a certain functionality being recited herein as “performed by the computer system” are assumed to be included as part of the computer system 150.

[0043] The vehicle 100 may further include a memory 154 readable / accessible by the computer system 150. The memory 154 may be a stand-alone memory, or may e.g. form part of the computer system 150 itself. The memory 154 may store e.g. a model of the vehicle 100, in form of for example mapped knowledge related to the active suspension that the computer system 150 may access and use to control the active suspension as will be described in more detail later herein. As used herein, a model of a vehicle may include a static, dynamic and / or kinematic mode of the vehicle.

[0044] The vehicle 100 may further include one or more sensors (not shown) for determining road conditions under at least the driven axle 120, in order to detect that a friction coefficient (mu, or ) between the ground and a wheel unit is lower on one side of the driven axle 120 than on the other side of the driven axle 120. Such one or more sensors may e.g. include / provide capability of visually scanning the ground surface and use one or more image processing / analysis algorithms for visually determining road surface conditions, such as patches of different surfaces / materials, etc. Other envisaged examples include sensors capable of detecting such differences based on e.g. wheel slip or similar. Other envisaged examples include sensors capable of detecting such differences using other forms of scanning techniques, such as by temperature readings, reflection readings, and similar. It is envisaged that e.g. various forms of machine learning may be used to train e.g. a camera to detect such different conditions, and similar. For the purpose of the present disclosure, it is not important exactly how it is determined that the friction conditions are different at the respective ends of the driven axle 120, as long as at least some indication of such different conditions may be provided.

[0045] The vehicle 100 may further include an interface 180 through which a current capability of the active suspension can be obtained. The interface 180 may be a stand-alone interface or provided e.g. as part of the computer system 150. The interface 180 may provide suspension capability information pertinent to the current capability of the active suspension.Such information may include e.g. current normal load forces on each of the wheel units 112, 114, 122 and 124; limitations for possible normal load forces (and / or changing rates) on each of the wheel units 112, 114, 122 and 124 after adjusting the active suspension, and / or limitations for possible distances (and / or changing rates) between each wheel unit 112, 114, 122 and 124 and the chassis of the vehicle (in the vertical direction). If not formed as part of the computer system 150, the interface 180 and computer system 150 may be communicatively connected, such that the computer system 150 may receive such information from the interface 180. The interface 180 may in turn be communicatively coupled to one or more sensors of the active suspension, such as the sensors 146a-d or other sensors (not shown) capable of providing such information about the active suspension capabilities.

[0046] The present disclosure aims at solving, or at least alleviating, the problem of vehicle handling under split-mu conditions (e.g. when friction is different for different wheel units on a same axle). In particular, the present disclosure aims at solving or at least alleviating such a problem during takeoff / starting of the vehicle 100 from standstill, or at least from a low speed and when the vehicle 100 is accelerated towards its intended cruising speed. The present disclosure proposes to solve this task by using the active suspension of the vehicle 100 to improve vehicle handling performance under split-mu conditions, and based on the current state of the differential 170.

[0047] How the computer system 150 is envisaged to operate to solve this task using the active suspension will now be described in more detail with reference also to FIG. 2.

[0048] FIG. 2 schematically illustrates a flowchart of an exemplary method 200 according to an example. The computer system 150 is envisaged as being capable of performing the various operations of the method 200.

[0049] As part of an operation S210 of the method 200, an indication is received of a desire to start the vehicle 100 from a standstill. The indication may e.g. come from the driver (or passenger) of the vehicle 100 pressing a particular button on the dashboard 160, selecting a particular menu option on a touch-sensitive display of the dashboard 160, by use of e.g. a smart phone running an application interacting with the computer system 150, or similar. The indication may also, in other examples, be automatically generated when it is detected that the driver presses, or is about to press, the throttle pedal when the vehicle is standing still, or similar. The indication may also, in other examples, come from some other system of thevehicle 100, such as for example an ADAS or ADS, or similar. Exactly how the indication is obtained by the computer system 150 is not of particular importance, as long as there is some way available of providing such an indication to the computer system 150, or as long as the computer system 150 may on its own somehow figure out that there is the desired intent to start the vehicle 100 from the standstill.

[0050] As part of an operation S220 of the method 200, performed before, simultaneously with, or after the operation S210, an indication is received of a surface friction on a first side of the driven axle 120 (i.e., between a wheel unit arranged on that first side and the underlying ground) of the vehicle 100 being lower than a surface friction on an opposite, second side of the driven axle 120. As mentioned earlier herein, such an indication may be generated by one or more suitable sensors, or even manually provided by e.g. a driver as part of the driver noticing that there are split-mu conditions on the ground / road. For example, the driver may be provided with a switch having at least two positions, such as a first position indicating that the friction is higher on the left side than on the right side, and a second position indicating that the opposite is true. The switch may also, of course, have a “neutral” position indicating that there are no split-mu conditions. By using such a switch, or other equivalent button, menu option or similar, the indication about the split-mu conditions may be provided to the computer system 150.

[0051] As part of an operation S230 of the method 200, performed before, simultaneously with, or after one or both of the operations S210 and S220, an indication is obtained about whether the differential 170 of the driven axle 120 is currently open (i.e. in the open state) or locked (i.e. in the locked state). Such an indication may be provided by the computer system 150 communication directly or indirectly with the differential 170, or by other suitable means.

[0052] As part of an operation S240 of the method, performed in response to the operations S210, S220 and S230, it is determined, based on the relevant indication, whether the differential is currently opened or locked.

[0053] If the differential 170 is open, the method 200 proceeds with an operation S250 in which the active suspension is controlled to increase a loading on the first side of the driven axle 120, i.e. at the side where the friction is lower. Increasing the loading on the lower- friction side (and thus making the wheel unit on the lower-friction side of the driven axle 120 harder to rotate) may cause more of the power from the propulsion system 174 to betransferred to the higher-friction side, and to increase overall traction and startability by better utilizing the higher-friction wheel unit. Optionally, the method 200 may then also proceed with an operation S252 (before, after or in parallel with the operation S250) in which the active suspension is controlled to decrease a loading on the second side of the driven axle 120, i.e. at the side where the friction is higher. This may cause the wheel unit on the lower- friction side to be even more hard to rotate, resulting in a further transfer of power to the wheel unit on the higher-friction side of the driven axle 120.

[0054] If the differential is instead determined to be locked, the method 200 proceeds with another operation S260 in which the active suspension is instead controlled to increase a loading on the second side of the driven axle 120, i.e. at the side where the friction is higher. By increasing the loading on the higher-friction side when the differential is locked, the power distributed to the wheel unit on the higher-friction side can be better utilized by increasing the normal load on that wheel unit, thereby improving startability also in such a situation. Optionally, the method 200 may then also proceed with an operation S262 (before, after or in parallel with the operation S260) in which the active suspension is controlled to decrease a loading on the first side of the driven axle 120, i.e. at the side where the friction is lower. This may further improve the utilization of the power transferred to the wheel unit on the higher-friction side, as that wheel unit will have the best traction out of the wheel units on the driven axle 120.

[0055] As an example, increasing (or decreasing) a loading on a particular side of the driven axle 120 may be performed by controlling the active suspension such that a center-of- gravity (COG) of the vehicle 100 is moved. For example, moving the COG closer towards a particular end of the driven axle 120 will increase a loading on the wheel unit at that side of the driven axle 120, while moving the COG of the vehicle 100 further away from the particular end of the driven axle 120 will instead decrease such a loading. For example, increasing a load at a particular corner of the vehicle can be achieved by for example raising the wheel unit at that particular comer, by raising the wheel units at the other corners, or a combination thereof. Similarly, decreasing a load at the particular corner of the vehicle can be achieved by for example lowering the wheel unit at that particular corner, by lowering the wheel units at the other corners, or a combination thereof, or similar.

[0056] As another example, a loading at a particular end of the driven axle 120 may also be achieved by using a torsional stiffness of the vehicle’s chassis, and to induce the desired forces at the particular end via the chassis.

[0057] As an example, different roll angles for the front and rear axles 110 and 120 of the vehicle can be used to either increase or decrease a loading on the particular end of the rear (driven) axle 120.

[0058] In one or more examples, a model that includes mapped knowledge of load shifts for different combinations of e.g. roll angles requested for the front and rear axles 110 and 120 can be used to control the active suspension to achieve the desired load shifting. For example, such mapped knowledge may include one or more mathematical expressions, and / or a collection of experimentally obtained load shifts for a plurality of different roll angle requests, or similar. Experiments may be performed in a lab environment, or include data collected during actual driving of the vehicle 100 in real-life situations. If the desired load shift is not found in such a collection, it is envisaged that interpolation and / or extrapolation can be used to estimate e.g. the necessary roll angles based by combining roll angles that produces load shifts sufficiently close to the desired load shift, and similar. Such mapped knowledge may, in some examples, e.g. include experimental values obtained for a plurality of different initial weight distributions, different initial loadings on each wheel unit and axle, etc., and can be used as part of finding the suitable roll angles to request in order to achieve the desire load shifting. The mapped knowledge and model may knowledge of gain or loss in normal forces at each vehicle comer / wheel unit for a given vehicle / axle motion and similar. Knowledge may e.g. be collected and catalogued to show how e.g. normal load forces Fzion each i :th wheel unit (or vehicle corner) depend on vertical distances dzibetween each wheel unit and the chassis of the vehicle, or e.g. vertical displacements dziof each wheel unit from a baseline value, or similar; how the distances dzidepend on normal load forces FZ(-; and / or e.g. how normal load forces Fzidepend on roll angles (for the vehicle as a whole or for individual axles of the vehicle), pitch angles, heave and / or COG position of the vehicle. Catalogued experimental data may also be complemented, or replaced, by e.g. a model-based algorithm describing the dynamics of the vehicle in terms of its active suspension and normal load forces. For example, with knowledge of certain parameters of the vehicle such as wheel base, track width, torsional stiffness of chassis and COG height, it is assumed that forexample a load transfer induced at an axle as a function of front / rear axle roll angles may be calculated.

[0059] In some examples, the computer system 150 and its processing circuitry may be further configured to obtain the suspension capability information, from e.g. the interface 180, and to use this suspension capability information when controlling the active suspension. The same interface 180 may also, in some examples, be used for the control of the active suspension, e.g. by sending standardized commands to the interface 180 and then let the interface 180 translate (if needed) these standardized commands to something that the active suspension may understand. The interface 180 may provide information such as current normal loads Fzion each i :th wheel unit, current distances / displacements dzi, current limits for Fziand / or dzi(i.e. FZlmand / or dzl"n), current limits for changes of Fziand / or dzi(i.e. AFz'mand / or dzl™), and / or current rate of change limits dFzi / dt and / or d(dzl)' / dt (e.g. “normal load changing rate limitations” and / or “level changing rate limitations”, e.g. Fzilimand / or dz'i)limand similar. Force limitations may in some examples include separate limits for e.g. raising and lowering of a wheel unit, etc.

[0060] If used to also control the active suspension, the interface 180 may for example receive commands such as requests for a particular normal load force Fzqto be exerted on the i :th wheel unit, a particular distance d^ to be configured for the i :th wheel unit, a particular change in normal load force Fzq, a particular change in distance Adzi, a request to achieve a certain normal load force Fzqor change in normal load force Fzqwhile remaining within a limitation in distancea request to achieve a certain distance dzrlqor change in distance dzreqwhile remaining within a limitation in normal load forceand similar.

[0061] Using the suspension capability information obtained from the interface 180 may provide a more efficient usage of the active suspension, e.g. by avoiding requesting normal load changes that are not currently obtainable, and / or by e.g. taking into account whether all suspension actuators (such as cylinders) for the wheel units are working properly (as a failure or reduced capacity of a particular such actuator may be signaled by the interface 180 by e.g. reducing the reported rate of change limitations, or similar). Similarly, if the attempted acceleration of the vehicle has already started, it may be preferably to prioritize normal load changes that can be made more quicker than others, based on e.g. the reported rate of changecapabilities of the active suspension, and similar. Other advantageous uses of the reported suspension capability information in order to optimize the use of the active suspension for vehicle takeoff / startability under split-mu conditions are of course also possible.

[0062] FIG. 3 schematically illustrates a setup 300 of an exemplary experiment performed to validate the proposed solution. This experiment was performed using a two- axled bus 100 equipped with active suspension and driven (via an open differential) on its rear axle 120 (such as illustrated in FIG. 1 A), and startability was tested by fully pressing on the throttle pedal (i.e. by requesting 100% acceleration) from standstill and taking notes of (e.g. recording) the longitudinal velocity obtained after 20 seconds (s) of attempted acceleration. The split-mu surface conditions were such that the friction was higher on the right (R) side of the bus 100 / road 320 than on the left side (L), wherein the lower-friction on the left side was caused by a patch 310 of icy surface on the road 320 along which the bus was driven during the experiment. As a baseline, the corner loads (i.e. normal loads on the respective wheel unit in the respective corner of the vehicle) for a setting of zero degrees roll angle on both the front and rear axle were 2740 kilograms (kg) at the front left comer, 2215 kg at the front right corner, 4120 kg at the rear left comer, and 4120 kg at the rear right corner. In the baseline test, the vehicle managed to reach a longitudinal velocity of 22.9 kilometers per hour (km / h) in 20 s.

[0063] The corner loads after requesting a front axle roll of -1 degrees and a rear axle roll of -3 degrees were 2810 kg for the front left corner, 2105 kg for the front right corner, 4360 kg for the rear left corner, and 3920 kg for the rear right corner. In this setting, the vehicle managed to reach a longitudinal velocity of 27 km / h in 20 s.

[0064] The corner loads after requesting a front axle roll of -2 degrees and a rear axle roll of -3 degrees were 2620 kg for the front left corner, 2290 kg for the front right corner, 4585 kg for the rear left corner, and 3695 kg for the rear right comer. In this setting, the vehicle managed to reach a longitudinal velocity of 34.3 km / h in 20 s.

[0065] Consequently, it can be seen that by shifting about 250 kg on the driven axle to the lower-mu / friction (left) side, the longitudinal velocity obtained in 20 s increased by approximately 4 km / h, while shifting about 450 kg on the driven axle to the lower- mu / friction (left) side increased the longitudinal velocity obtained in 20 s by 11.4 km / h.

[0066] FIG. 4 schematically illustrates a diagram of an exemplary computer system 400 for implementing examples disclosed herein, such as e.g. the computer system 150, in moredetail. The computer system 400 is adapted to execute instructions from a computer-readable medium to perform these and / or any of the functions or processing described herein. The computer system 400 may be connected (e.g., networked) to other machines in a LAN (Local Area Network), LIN (Local Interconnect Network), automotive network communication protocol (e.g., FlexRay), an intranet, an extranet, or the Internet. While only a single device is illustrated, the computer system 400 may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Accordingly, any reference in the disclosure and / or claims to a computer system, computing system, computer device, computing device, control system, control unit, electronic control unit (ECU), processor device, processing circuitry, etc., includes reference to one or more such devices to individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. For example, control system may include a single control unit or a plurality of control units connected or otherwise communicatively coupled to each other, such that any performed function may be distributed between the control units as desired. Further, such devices may communicate with each other or other devices by various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc.

[0067] The computer system 400 may comprise at least one computing device or electronic device capable of including firmware, hardware, and / or executing software instructions to implement the functionality described herein. The computer system 400 may include processing circuitry 402 (e.g., processing circuitry including one or more processor devices or control units), a memory 404, and a system bus 406. The computer system 400 may include at least one computing device having the processing circuitry 402. The system bus 406 provides an interface for system components including, but not limited to, the memory 404 and the processing circuitry 402. The processing circuitry 402 may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory 404. The processing circuitry 402 may, for example, include a general-purpose processor, an application specific processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic device, discrete gate or transistor logic, discrete hardware components,or any combination thereof designed to perform the functions described herein. The processing circuitry 402 may further include computer executable code that controls operation of the programmable device.

[0068] The system bus 406 may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and / or a local bus using any of a variety of bus architectures. The memory 404 may be one or more devices for storing data and / or computer code for completing or facilitating methods described herein. The memory 404 may include database components, object code components, script components, or other types of information structure for supporting the various activities herein. Any distributed or local memory device may be utilized with the systems and methods of this description. The memory 404 may be communicably connected to the processing circuitry 402 (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for executing one or more processes described herein. The memory 404 may include non-volatile memory 408 (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory 410 (e.g., randomaccess memory (RAM)), or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a computer or other machine with processing circuitry 402. A basic input / output system (BIOS) 412 may be stored in the non-volatile memory 408 and can include the basic routines that help to transfer information between elements within the computer system 400.

[0069] The computer system 400 may further include or be coupled to a non-transitory computer-readable storage medium such as the storage device 414, which may comprise, for example, an internal or external hard disk drive (HDD) (e.g., enhanced integrated drive electronics (EIDE) or serial advanced technology attachment (SATA)), HDD (e.g., EIDE or SATA) for storage, flash memory, or the like. The storage device 414 and other drives associated with computer-readable media and computer-usable media may provide nonvolatile storage of data, data structures, computer-executable instructions, and the like.

[0070] Computer-code which is hard or soft coded may be provided in the form of one or more modules. The module(s) can be implemented as software and / or hard-coded in circuitry to implement the functionality described herein in whole or in part. The modules may bestored in the storage device 414 and / or in the volatile memory 410, which may include an operating system 416 and / or one or more program modules 418. All or a portion of the examples disclosed herein may be implemented as a computer program 420 stored on a transitory or non-transitory computer-usable or computer-readable storage medium (e.g., single medium or multiple media), such as the storage device 414, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the processing circuitry 402 to carry out actions described herein. Thus, the computer-readable program code of the computer program 420 can comprise software instructions for implementing the functionality of the examples described herein when executed by the processing circuitry 402. In some examples, the storage device 414 may be a computer program product (e.g., readable storage medium) storing the computer program 420 thereon, where at least a portion of a computer program 420 may be loadable (e.g., into a processor) for implementing the functionality of the examples described herein when executed by the processing circuitry 402. The processing circuitry 402 may serve as a controller or control system for the computer system 400 that is to implement the functionality described herein.

[0071] The computer system 400 may include an input device interface 422 configured to receive input and selections to be communicated to the computer system 400 when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processing circuitry 402 through the input device interface 422 coupled to the system bus 406 but can be connected through other interfaces, such as a parallel port, an Institute of Electrical and Electronic Engineers (IEEE) 1394 serial port, a Universal Serial Bus (USB) port, an IR interface, and the like. The computer system 400 may include an output device interface 424 configured to forward output, such as to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system 400 may include a communications interface 426 suitable for communicating with a network as appropriate or desired.

[0072] The operational actions described in any of the exemplary aspects herein are described to provide examples and discussion. The actions may be performed by hardware components, may be embodied in machine-executable instructions to cause a processor to perform the actions, or may be performed by a combination of hardware and software. Although a specific order of method actions may be shown or described, the order of theactions may differ. In addition, two or more actions may be performed concurrently or with partial concurrence.

[0073] Finally, more generalized computer systems falling with the envisaged examples of the present disclosure will now be described with reference also to FIGS. 5A and 5B.

[0074] FIG. 5A schematically illustrates an exemplary computer system 500 (that may correspond to e.g. the computer system 150 described earlier herein with reference to FIGS.1 A and IB and / or the computer system 400 described with reference to FIG. 4). The computer system 500 includes processing circuitry 510, that is configured to obtain an indication (via a message, such as a signal, reading, detection, etc., 520) of a desire to start a vehicle with which the computer system 500 is associated from a standstill, as described earlier herein. Here, “associated” means that the computer system may e.g. form part of the vehicle or vehicle unit, or e.g. be provided separately from the vehicle or vehicle unit but still able to control the required functionality of the vehicle or vehicle unit. The computer system 500 may e.g. form part of a cloud service, server, or similar, with which the vehicle or vehicle unit is configured to communicate.

[0075] The computer system 500 and processing circuitry 510 are further configured to obtain another indication of a surface friction on a first side of a driven axle of the vehicle being lower than a surface friction on an opposite, second side of the vehicle. Using the exemplary experiment described with reference to FIG. 3 as reference, the first side may e.g. be the left side (L) of the vehicle 100 / road 320 and the second side may be the right side (R) of the vehicle 100 / road 320, as the surface friction (mu or / z) on the left side is lower due to the presence of the icy patch 310. The indication about the surface friction may be provided as part of a message 530 provided from e.g. one or more suitable sensors 532 of the vehicle, or similar, as described herein.

[0076] The computer system 500 and processing circuitry 510 are further configured to obtain yet another indication about whether a differential 542 (e.g. the differential 170 of FIG. IB) of the driven axle is open or locked, e.g. as part of a message (540) provided from the differential 542 or from any other entity capable of providing such information to the computer system 500.

[0077] The computer system 500 and processing circuitry 510 are further configured to, based on the indications received as 520, 530 and 540, control an active suspension 552 (such as described with reference to e.g. FIGS. 1 A and IB, and via for example a control message550) of the vehicle to increase a loading on the first side of the driven axle in response to the differential 542 being open, and to control the active suspension 552 of the vehicle to increase a loading on the second side of the vehicle in response to the differential 542 being closed.

[0078] FIG. 5B schematically illustrates another exemplary computer system 501 similarly to the computer system 500, but with differences as described below.

[0079] The computer system 500 and proc6essing circuitry 510 may be further configured to use a model (e.g. mapped knowledge) 560 of the vehicle and active suspension as described earlier herein. The model 560 may e.g. be stored in and accessible from a memory 562, in form of e.g. mapped knowledge.

[0080] The control system 501 and processing circuitry 510 may also be configured to communicate with an interface 582 (such as interface 180) from which suspension capability information (as described earlier herein, as part of e.g. a signal / message / indication 580) can be provided to the control system 501 and processing circuitry 510, such that the processing circuitry 510 may take the current capabilities of the active suspension 552 into account when e.g. determining how to change the normal load forces on the axles and / or wheel units of the vehicle in order to improve startability as described herein. In some examples, it is envisaged that the interface 582 may, in addition to providing suspension capabilities, also receive control commands for the active suspension 552, in which case the computer system 501 and processing circuitry 510 may instead (or in addition) control the active suspension 552 via the interface 582 (in which case the messaging / signaling / indicating 580 is two-way and the control message(s) 550 may not be needed). For example, the interface 582 may provide a standardized interface with a standardized set of possible control commands as well as e.g. a standardized set of suspension capabilities that are reported from the interface 582 to the computer system 501 and processing circuitry 510. As described earlier herein, this may be advantageous in that the computer system 501 may not need to know the exact configuration of the active suspension 552, as the interface 582 will serve as a translator between active suspension 552 specific-details to a standardized language that the computer system 501 may understand.

[0081] In summary of all of the above, the present disclosure improves upon currently available technology in that it makes use of the active suspension of the vehicle in order to improve startability under split-mu conditions. In particular, the present disclosure proposesto take into account the state of a differential of a driven axle of the vehicle, as part of deciding how to use the active suspension to change the normal load forces on the axle and wheel units of the vehicle in order to obtain best possible traction given the prevailing split- mu conditions. This helps to e.g. more faster reaching a desired speed, or to reach a higher speed within a preset time interval, as has been experimentally verified and described herein.

[0082] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0083] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0084] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0085] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of thisspecification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0086] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

[0087] The following is an exemplifying list of examples envisaged herein:Example 1 : A computer system (150, 400, 500, 501) for a heavy vehicle (100) equipped with an active suspension (552), the computer system including processing circuitry (410, 510) configured to: - obtain an indication (520) of a desire to start the vehicle from a standstill; - obtain an indication (530) of a surface friction ( ) on a first side (R) of a driven axle (120) of the vehicle being lower than a surface friction on an opposite, second side (L) of the driven axle; - obtain an indication (540) about whether a differential (170, 542) of the driven axle is currently open or locked; - in response to the differential being open, control (550) the active suspension to increase a loading on the first side of the driven axle, and - in response to the differential being locked, control the active suspension to increase a loading on the second side of the driven axle.Example 2: The computer system of example 1, wherein the processing circuitry is further configured to: - in response to the differential being open, control the active suspension to decrease a loading on the second side of the driven axle, and - in response to the differential being locked, control the active suspension to decrease a loading on the first side of the driven axle.Example 3 : The computer system of example 1 or 2, wherein increasing the loading on the first or second side of the driven axle includes to control the active suspension to move a center-of-gravity, COG, of the vehicle.Example 4: The computer system of any one of examples 1 to 3, wherein increasing the loading on the first or second side of the driven axle includes to control the active suspension to increase the loading by one or more forces on the driven axle induced by a torsional stiffness of a chassis of the vehicle.Example 5: The computer system of example 4, wherein increasing the loading on the first or second side of the driven axle includes to request different roll angles from front and rear axle groups of the vehicle.Example 6: The computer system of any one of the preceding examples, wherein the processing circuitry is further configured to control the active suspension based on a model (560) of the vehicle.Example 7: The computer system of example 6, wherein the model includes a mapped knowledge of load shifts for different combinations of roll angles requested from front and rear axles groups of the vehicle.Example 8: The computer system of example 6 or 7, wherein the model includes a modelbased algorithm for the vehicle.Example 9: The computer system (501) of any one of the preceding examples, wherein the processing circuitry is further configured to obtain suspension capability information (580) pertinent to a current capability of the active suspension of the vehicle, and to control the active suspension also based on the suspension capability information.Example 10: The computer system of example 9, wherein the processing circuitry is further configured to both obtain the suspension control information and control (580) the active suspension of the vehicle via a same suspension control / capability interface (582).Example 11 : The computer system of any one of the preceding examples, wherein the processing circuitry is further configured to, in response to the differential being open and instead of increasing a loading on the first side of the driven axle, control the differential to its locked state and then control the active suspension to increase a loading on the second side of the driven axle.Example 12: A heavy vehicle (100) including: - an active suspension (552), - at least one driven axle (120), and - the computer system (150, 400, 500) of any one of examples 1 to 10.Example 13: The vehicle of example 12, wherein the active suspension is a gas-hydraulic suspension and / or pneumatic suspension.Example 14: A computer-implemented method (200) for improving startability of a heavy vehicle having active suspension, including: - obtaining (S210) an indication of a desire to start the vehicle from a standstill; - obtaining (S220) an indication of a surface friction on a first side of a driven axle of the vehicle being lower than a surface friction on an opposite, second side of the driven axle; - obtaining (S230) an indication about whether a differentialof the driven axle is open or locked, and - controlling (S250, S260) the active suspension to increase a loading on either the first side of the driven axle or on the second side of the driven axle, depending (S240) on whether the differential is open or locked.Example 15: The method of example 14, wherein controlling the active suspension includes to increase (S250) a loading on the first side of the driven axle in response to the differential being open.Example 16: The method of example 14, wherein controlling the active suspension includes to increase (S260) a loading on the second side of the driven axle in response to the differential being locked.Example 17: The method of example 15, wherein controlling the active suspension includes to decrease (S252) a loading on the second side of the driven axle in response to the differential being open.Example 18: The method of example 16, wherein controlling the active suspension includes to decrease (S262) a loading on the first side of the driven axle in response to the differential being locked.Example 19: A computer program product (414) including program code (420) for performing, when executed by a processing circuitry (402) of a computer system (400), the method of any one of examples 14 to 18.Example 20: A non-transitory computer-readable storage medium (414) including instructions (420), which when executed by a processing circuitry (402) of a computer system (400), cause the processing circuitry to perform the method of any one of examples 14 to 18.

Claims

ClaimsWhat is claimed is:

1. A computer system (150, 400, 500, 501) for a heavy vehicle (100) equipped with an active suspension (552), the computer system comprising processing circuitry (410, 510) configured to:- obtain an indication (520) of a desire to start the vehicle from a standstill;- obtain an indication (530) of a surface friction ( ) on a first side (R) of a driven axle (120) of the vehicle being lower than a surface friction on an opposite, second side (L) of the driven axle;- obtain an indication (540) about whether a differential (170, 542) of the driven axle is currently open or locked;- in response to the differential being open, control (550) the active suspension to increase a loading on the first side of the driven axle, and- in response to the differential being locked, control the active suspension to increase a loading on the second side of the driven axle.

2. The computer system of claim 1, wherein the processing circuitry is further configured to:- in response to the differential being open, control the active suspension to decrease a loading on the second side of the driven axle, and- in response to the differential being locked, control the active suspension to decrease a loading on the first side of the driven axle.

3. The computer system of claim 1 or 2, wherein increasing the loading on the first or second side of the driven axle comprises to control the active suspension to move a center-of- gravity, COG, of the vehicle.

4. The computer system of any one of claims 1 to 3, wherein increasing the loading on the first or second side of the driven axle comprises to control the active suspension to increase the loading by one or more forces on the driven axle induced by a torsional stiffness of a chassis of the vehicle.

5. The computer system of claim 4, wherein increasing the loading on the first or second side of the driven axle comprises to request different roll angles from front and rear axle groups of the vehicle.

6. The computer system of any one of the preceding claims, wherein the processing circuitry is further configured to control the active suspension based on a model (560) of the vehicle.

7. The computer system of claim 6, wherein the model comprises a mapped knowledge of load shifts for different combinations of roll angles requested from front and rear axles groups of the vehicle.

8. The computer system of claim 6 or 7, wherein the model comprises a model-based algorithm for the vehicle.

9. The computer system (501) of any one of the preceding claims, wherein the processing circuitry is further configured to obtain suspension capability information (580) pertinent to a current capability of the active suspension of the vehicle, and to control the active suspension also based on the suspension capability information.

10. The computer system of claim 9, wherein the processing circuitry is further configured to both obtain the suspension control information and control (580) the active suspension of the vehicle via a same suspension control / capability interface (582).

11. The computer system of any one of the preceding claims, wherein the processing circuitry is further configured to, in response to the differential being open and instead of increasing a loading on the first side of the driven axle, control the differential to its locked state and then control the active suspension to increase a loading on the second side of the driven axle.

12. A heavy vehicle (100) comprising:- an active suspension (552),- at least one driven axle (120), and- the computer system (150, 400, 500) of any one of claims 1 to 10.

13. The vehicle of claim 12, wherein the active suspension is a gas-hydraulic suspension and / or pneumatic suspension.

14. A computer-implemented method (200) for improving startability of a heavy vehicle having active suspension, comprising:- obtaining (S210) an indication of a desire to start the vehicle from a standstill;- obtaining (S220) an indication of a surface friction on a first side of a driven axle of the vehicle being lower than a surface friction on an opposite, second side of the driven axle;- obtaining (S230) an indication about whether a differential of the driven axle is open or locked, and- controlling (S250, S260) the active suspension to increase a loading on either the first side of the driven axle or on the second side of the driven axle, depending (S240) on whether the differential is open or locked.

15. The method of claim 14, wherein controlling the active suspension comprises to increase (S250) a loading on the first side of the driven axle in response to the differential being open.

16. The method of claim 14, wherein controlling the active suspension comprises to increase (S260) a loading on the second side of the driven axle in response to the differential being locked.

17. The method of claim 15, wherein controlling the active suspension comprises to decrease (S252) a loading on the second side of the driven axle in response to the differential being open.

18. The method of claim 16, wherein controlling the active suspension comprises to decrease (S262) a loading on the first side of the driven axle in response to the differential being locked.

19. A computer program product (414) comprising program code (420) for performing, when executed by a processing circuitry (402) of a computer system (400), the method of any one of claims 14 to 18.

20. A non-transitory computer-readable storage medium (414) comprising instructions (420), which when executed by a processing circuitry (402) of a computer system (400), cause the processing circuitry to perform the method of any one of claims 14 to 18.

Images