Force constraints for vehicle actuation

Abstract

A computer system configured for controlling a vehicle is disclosed. The vehicle is configured to respond to motion requests by operating motion support devices for actuating the vehicle, in response to actuator instructions which are based on the motion requests. The computer system is configured to apply constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuator instructions. The constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces. A first region is associated with default force allocation, and corresponds to values of the force(s) for which a first threshold condition is satisfied. A second region is associated with restricted force allocation, and corresponds to values of the force(s) for which a second threshold condition is satisfied and the first threshold condition is unsatisfied. A third region is associated with un-allowed force allocation, and corresponds to values of the force(s) for which the first and second threshold conditions are unsatisfied. Corresponding vehicle, computer-implemented method, computer program product, and non-transitory computer-readable storage medium are also disclosed.

Description

FORCE CONSTRAINTS FOR VEHICLE ACTUATIONTECHNICAL FIELD

[0001] The disclosure relates generally to vehicle motion control. In particular aspects, the disclosure relates to force constraints for vehicle actuation. 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, the disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] Generally, the field of vehicle motion control includes various tasks. One example task is allocation of lateral and / or longitudinal forces based on motion requests.

[0003] A problem with existing approaches for allocation of lateral and / or longitudinal forces is that improper allocation may cause unsafe vehicle behavior and / or fail to utilize the full motion potential of the vehicle.

[0004] Therefore, there is a need for alternative approaches to force allocation for a vehicle.SUMMARY

[0005] Various aspects may aim to solve, mitigate, alleviate, or eliminate at least some of the above or other disadvantages.

[0006] According to a first aspect of the disclosure, a computer system configured for controlling a vehicle is provided, wherein the vehicle comprises a plurality of motion support devices for actuating the vehicle and a control allocator for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions. The computer system comprises processing circuitry configured to apply constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuator instructions, wherein the constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces. The regions include at least: a first region corresponding to values of the lateral and / or longitudinal forces for which a firstthreshold condition is satisfied, wherein the first region is associated with default force allocation, a second region corresponding to values of the lateral and / or longitudinal forces for which a second threshold condition is satisfied and for which the first threshold condition is unsatisfied, wherein the second region is associated with restricted force allocation, and a third region corresponding to values of the lateral and / or longitudinal forces for which the first and second threshold conditions are unsatisfied, wherein the third region is associated with un-allowed force allocation. The first aspect of the disclosure may seek to improve force allocation for a vehicle. A technical benefit may include that excessive and / or over-moderate allocation of forces is mitigated, since the uncertainty of parameter estimation is taken into account when allocating forces. This may lead to improved safety for the vehicle operation, and improved utilization of the motion potential of the vehicle.

[0007] According to a second aspect of the disclosure, a computer-implemented method for controlling a vehicle is provided, wherein the vehicle comprises a plurality of motion support devices for actuating the vehicle and a control allocator for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions. The method comprises applying, by processing circuitry of a computer system, constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuator instructions, wherein the constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces. The regions include at least: a first region corresponding to values of the lateral and / or longitudinal forces for which a first threshold condition is satisfied, wherein the first region is associated with default force allocation, a second region corresponding to values of the lateral and / or longitudinal forces for which a second threshold condition is satisfied and for which the first threshold condition is unsatisfied, wherein the second region is associated with restricted force allocation, and a third region corresponding to values of the lateral and / or longitudinal forces for which the first and second threshold conditions are unsatisfied, wherein the third region is associated with un-allowed force allocation. The second aspect of the disclosure may seek to improve force allocation for a vehicle. A technical benefit may include that excessive and / or over-moderate allocation of forces is mitigated, since the uncertainty of parameter estimation is taken into account when allocating forces. This maylead to improved safety for the vehicle operation, and improved utilization of the motion potential of the vehicle.

[0008] Optionally in some examples, including in at least one preferred example, the constraints on lateral and / or longitudinal forces comprise respective constraints on lateral and / or longitudinal forces for each of one or more wheel(s) of the vehicle, or respective constraints on lateral and / or longitudinal forces for each of one or more wheel combination(s) of the vehicle. For example, a wheel combination may be the wheels of a same wheel axle, or the wheels of a same vehicle unit (e.g., a tractor unit, or a trailer unit). A technical benefit may include that the force allocation may be differently constrained for different wheels (or wheel combinations); e.g., depending on respective estimation values and / or uncertainties for the different wheels (or wheel combinations). This may further improve the force allocation.

[0009] Optionally in some examples, including in at least one preferred example, the second region comprises two or more sub-regions defined by one or more further threshold condition(s), wherein different sub-regions are associated with different restrictions of the force allocation. A technical benefit may include that the force allocation may be more flexibly constrained. This may further improve the force allocation.

[0010] Optionally in some examples, including in at least one preferred example, each of the threshold conditions forms a circle, or an ellipsoid, or a polygon in a value space of the lateral and / or longitudinal forces. A technical benefit may include adequate utilization of the motion potential of the vehicle.

[0011] Optionally in some examples, including in at least one preferred example, the restricted force allocation is implemented by application of increased penalty in a cost function. A technical benefit may include that the force allocation can be flexibly restricted.

[0012] Optionally in some examples, including in at least one preferred example, the penalty increases with increasing values of the lateral and / or longitudinal forces in the second region. A technical benefit may include that - within the second region - the likelihood of allocation decreases with increasing force values. Thereby, it is possible (allowed) to allocate relatively high forces close to an upper limit of estimation uncertainty, but such allocation can be restricted to certain situations (e.g., when it is highly necessary for safety reasons).

[0013] Optionally in some examples, including in at least one preferred example, at least one of the threshold conditions is based on an estimation uncertainty for tire-road frictionand / or normal load. A technical benefit may include that the force allocation is flexibly restricted based on tire-road friction and / or normal load.

[0014] Optionally in some examples, including in at least one preferred example, the first threshold condition is based on a lower bound associated with the estimation uncertainty. A technical benefit may include that the first region defines force allocation values that can - certainly, or with relatively high probability - be fulfilled by the motion support devices.

[0015] Optionally in some examples, including in at least one preferred example, the first threshold condition is further based on one or more slack variable(s) for tuning the restricted force allocation. A technical benefit may include that the boundary between the first and second regions can be flexibly adjusted in relation to the lower bound associated with the estimation uncertainty.

[0016] Optionally in some examples, including in at least one preferred example, the second threshold condition is based on an upper bound associated with the estimation uncertainty. A technical benefit may include that the third region defines force allocation values for which there is a relatively high probability that they cannot be fulfilled by the motion support devices. Alternatively or additionally, a technical benefit may include that the second region defines force allocation values that can possibly - with low to medium probability - be fulfilled by the motion support devices.

[0017] Optionally in some examples, including in at least one preferred example, at least one of the threshold conditions corresponds to a specific probability that the actual tire-road friction and / or normal load exceeds a threshold value, given currently estimated tire-road friction and / or normal load. A technical benefit may include that the regions may be flexibly defined in relation to specific probabilities of force allocation fulfillment by the motion support devices.

[0018] According to a third aspect of the disclosure, a vehicle is provided comprising the computer system of the first aspect and / or processing circuitry configured to perform the method of the second aspect. The third aspect of the disclosure may seek to provide a vehicle with improved force allocation.

[0019] According to a fourth aspect of the disclosure, a computer program product is provided, which comprises program code for performing, when executed by the processing circuitry, the method of the second aspect. The fourth aspect of the disclosure may seek to convey program code for improving the force allocation of a vehicle. A technical benefit mayinclude that new vehicles and / or legacy vehicles may be conveniently configured, by software installation / update, to apply constraints on lateral and / or longitudinal forces as a part of transforming motion requests to actuator instructions, wherein the constraints correspond to two or more threshold conditions defining at least three value regions of the lateral and / or longitudinal forces.

[0020] According to a fifth aspect of the disclosure, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium comprises instructions, which when executed by the processing circuitry, cause the processing circuitry to perform the method the second aspect. The fifth aspect of the disclosure may seek to convey program code for improving the force allocation of a vehicle. A technical benefit may include that new vehicles and / or legacy vehicles may be conveniently configured, by software installation / update, to apply constraints on lateral and / or longitudinal forces as a part of transforming motion requests to actuator instructions, wherein the constraints correspond to two or more threshold conditions defining at least three value regions of the lateral and / or longitudinal forces.

[0021] 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.

[0022] Some 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.

[0023] 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

[0024] Examples are described in more detail below with reference to the appended drawings.

[0025] FIG. 1 is a flowchart illustrating a method according to some examples.

[0026] FIG. 2 is a schematic drawing illustrating a vehicle according to some examples.

[0027] FIG. 3A is a schematic diagram illustrating value regions of lateral and longitudinal forces according to some examples.

[0028] FIG. 3B is a schematic diagram illustrating value regions of lateral and longitudinal forces according to some examples.

[0029] FIG. 3C is a schematic diagram illustrating value regions of lateral and longitudinal forces according to some examples.

[0030] FIG. 4A is a schematic diagram illustrating penalty of a cost function according to some examples.

[0031] FIG. 4B is a schematic diagram illustrating penalty of a cost function according to some examples.

[0032] FIG. 4C is a schematic diagram illustrating value regions of longitudinal force and corresponding cost function penalty according to some examples.

[0033] FIG. 5 is a schematic block diagram illustrating a control apparatus according to some examples.

[0034] FIG. 6 is a schematic block diagram illustrating actuation control according to some examples.

[0035] FIG. 7 is a schematic diagram illustrating a computer system for implementing examples disclosed herein, according to some examples.

[0036] FIG. 8 is a schematic drawing illustrating a computer program product, in the form of a non-transitory computer-readable storage medium, according to some examples.

[0037] FIG. 9 is a schematic block diagram of a control unit according to some examples.DETAILED DESCRIPTION

[0038] 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.

[0039] Examples of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. The solutions disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the examples set forth herein.

[0040] As already mentioned, a problem with existing approaches for force allocation of lateral and / or longitudinal for a vehicle is that improper allocation may cause unsafe vehicle behavior and / or fail to utilize the full motion potential of the vehicle.

[0041] This may - at least partially - be due to that the force allocation is based on estimated parameter values (e.g., tire-road friction coefficient values and / or normal load values). Estimation of parameter values is typically associated with some uncertainty regarding the accuracy of the estimation. Thus, an estimated parameter value may be higher, or lower, than the actual parameter value, which may lead to suboptimal force allocation.

[0042] For example, when an estimated friction coefficient is higher than the actual friction, the force allocation may presume that there is a relatively high force capacity available for allocation since the estimated friction coefficient indicates high grip. The vehicle operation may become unsafe due to excessive allocation of lateral and / or longitudinal force.

[0043] On the other hand, when an estimated friction coefficient is lower than the actual friction, the force allocation may presume that there is a relatively low force capacity available for allocation since the estimated friction coefficient indicates low grip. The vehicle operation may not utilize the full potential of the vehicle due to over-moderate allocation of lateral and / or longitudinal force.

[0044] These and / or other problems relating to vehicle motion management may be solved, or at least mitigated, by applying constraints on lateral and / or longitudinal forces when transforming motion requests to actuator instructions, wherein the constraints correspond to two or more threshold conditions defining at least three value regions (a.k.a., “grip zones”) of the lateral and / or longitudinal forces. By using at least three grip zones, the force allocation can be adaptively restricted. Thereby, the force allocation may be improved; e.g., avoiding or reducing the issuing of actuator requests that are not possible to fulfill, and / or avoiding or reducing unnecessary limitations of allocated forces. Generally, the term “actuator instruction” includes any suitable instruction (e.g., a request) to an actuator (i.e., a motion support device - MSD). Examples of actuator instructions include requests for one or more of: force, torque, wheel speed, wheel slip, etc.

[0045] The regions preferably include a first region for default (non-restricted) force allocation, a second region for restricted force allocation, and a third region for un-allowed force allocation. For example, the first region may correspond to force values which can almost certainly be fulfilled given the estimation uncertainty, the second region may correspond to force values which might be possible to fulfill given the estimation uncertainty,and the third region may correspond to force values which can almost certainly not be fulfilled given the estimation uncertainty.

[0046] Typically, force allocation within the first region is considered unproblematic and force allocation within the third region is not allowed, while force allocation within the second region is allowed, but should only be used in scenarios where relatively high total force is crucially needed (e.g., for safety reasons).

[0047] Generally, the constraints on lateral and / or longitudinal forces may be implemented for any suitable portion of a vehicle. For example, the constraints may be implemented at wheel level (individual constraints for each controlled wheel), at axle level (individual constraints for each controlled wheel axle), at vehicle unit level (individual constraints for each controlled vehicle unit), or at vehicle level (same constraints for entire vehicle). It should be noted that other wheel combinations are also possible for application of collective constraints (e.g., same constraints for all controlled wheel on one side of a vehicle, etc.). Thus, the constraints may comprise respective constraints for each of one or more wheel(s) of a vehicle, or respective constraints for each of one or more wheel combination(s) of the vehicle.

[0048] FIG. 1 illustrates a method 100 according to some examples. The method 100 is a computer-implemented method for controlling a vehicle. The method 100 may, for example, be performed by processing circuitry (e.g., processing circuitry) of a computer system.

[0049] The method 100 is suitable for a vehicle, which comprises a plurality of motion support devices for actuating the vehicle and a control allocator for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions.

[0050] As illustrated by optional step 110, the method 100 may comprise acquiring the motion requests. For example, the motion requests may originate from driver controls of the vehicle (e.g., steering wheel, accelerator pedal, brake pedal, etc.). Alternatively or additionally, the motion requests may originate from an autonomous - or semi-autonomous - driving control function of the vehicle (e.g., requesting longitudinal speed, longitudinal acceleration, steering angle, etc.).

[0051] As illustrated by step 120, the method 100 comprises applying constraints on lateral and / or longitudinal forces as a part of (i.e., when) transforming the motion requests to the actuator instructions.

[0052] The constraints correspond to two or more threshold conditions defining at least three value regions of the lateral and / or longitudinal forces: a first region associated with default force allocation, a second region associated with restricted force allocation, and a third region associated with un-allowed force allocation.

[0053] Generally, restricted force allocation may be defined in any suitable way. Typically, the restricted force allocation is defmed / implemented such that it is less likely to be used than the default force allocation. For example, the restricted force allocation may be implemented by application of increased penalty in a cost function (compared to the default force allocation), which is used by a control allocator to determine allocation of lateral and / or longitudinal forces. An increased penalty in the cost function typically renders the corresponding force values less likely to be allocated.

[0054] As illustrated by optional step 130, the method 100 may also comprise operating one or more motion support device (MSD) based on the actuator instructions.

[0055] FIG. 2 schematically illustrates an example vehicle 200 for cargo transport where the techniques disclosed herein can be advantageously applied. The vehicle 200 comprises a truck / tractor / towing unit 210 configured to tow one or more trailer unit(s) 211, 212 in a known manner. The tractor unit 210 and / or the trailer unit(s) 211, 212 may comprise a vehicle control unit (VCU) 290 configured to perform various vehicle (unit) control functions, such as vehicle motion management (VMM). For example, any of one or more VCU(s) 290 may be configured to perform one or more steps of the method 100 of FIG. 1. Thus, the techniques disclosed herein may be performed by any of one or more VCU(s) 290.

[0056] FIG. 3A illustrates value regions of lateral and longitudinal forces according to some examples. The diagram shows the lateral force Fyon the horizontal axis (x-axis), and the longitudinal force Fxon the vertical axis (y-axis). The first region 310, which is associated with default force allocation, corresponds to values of the lateral and longitudinal forces for which a first threshold condition is satisfied. The first threshold condition is shown as a circle 315, and can be expressed as Fx+ Fy< Cx. The second region 320 (gray ring), which is associated with restricted force allocation, corresponds to values of the lateral and longitudinal forces for which the first threshold condition is unsatisfied (i.e., Fx+ Fy> Cx)and a second threshold condition is satisfied. The second threshold condition is shown as a circle 325, and can be expressed as F + Fy << C2. The third region 340, which is associated with un-allowed force allocation, corresponds to values of the lateral and longitudinal forces for which the first and second threshold conditions are unsatisfied (i.e., Fx + Fy > C2). It can be seen that the threshold conditions form circles in the value space of the lateral and longitudinal forces.

[0057] FIG. 3B illustrates value regions of lateral and longitudinal forces according to some examples. The diagram shows the lateral force on the horizontal axis (x-axis), and the longitudinal force on the vertical axis (y-axis). Compared to the value regions of FIG. 3A, it can be seen that the second region comprises two sub-regions 320’ (light gray ring), 330 (dark gray ring). The sub-regions are associated with different restrictions of the force allocation. Typically, a sub-region 330 that represents higher total force allocation than another sub-region 320’ is associated with the more restrictive force allocation. The two subregions 320’, 330 are defined by a further threshold condition, which is shown as a circle 335, and can be expressed as F + Fy << C3< C2. The sub-region 320’ corresponds to values of the lateral and longitudinal forces for which the first threshold condition is unsatisfied (i.e., F + Fyand the further threshold condition is satisfied, and the sub-region 330 corresponds to values of the lateral and longitudinal forces for which the second threshold condition is satisfied (i.e., F + Fy < C2) and the further threshold condition is unsatisfied (i.e., F + Fy > C3). It should be noted that, generally, the second region can be divided into any suitable number of sub-regions.

[0058] Typically, the threshold conditions 315, 325, 335 are based on a parameter estimation uncertainty (e.g., for tire-road friction and / or normal load). Also shown in FIG. 3B is a circle 350 representing an example force allocation boundary resulting from using only the estimated parameter value(s) without consideration of the estimation uncertainty. If such a constraint on lateral and longitudinal forces was used, there would be only two value regions; one associated with default force allocation for values within the circle 350, and one associated with un-allowed force allocation for values outside the circle 350.

[0059] Then, it would not be possible (allowed) to allocate forces outside the circle 350, even if there is some possibility that such forces can be achieved by the MSD(s) if the parameter estimation was too pessimistic, and even if such force allocation could bebeneficial in some scenarios (e.g., to exit an unsafe situation). Hence, the constraint 350 is over-moderate, and the full motion potential of the vehicle would not be utilized. This problem is alleviated by the use of a second threshold condition being more generous than the circle 350.

[0060] Furthermore, it would be possible (allowed) to allocate forces inside - but relatively close to - the circle 350, even if there is some possibility that such forces cannot be achieved by the MSD(s) if the parameter estimation was too optimistic. Hence, the constraint 350 may cause excessive force allocation. This problem is alleviated by the use of a first threshold condition being less generous than the circle 350, and higher cost function penalty for allocations within the second region than for allocations within the first region.

[0061] FIG. 3C illustrates value regions of lateral and longitudinal forces according to some examples. The diagram shows the lateral force on the horizontal axis (x-axis), and the longitudinal force on the vertical axis (y-axis). Compared to the value regions of FIG. 3B, it can be seen that the threshold conditions do not form circles, but ellipsoids in the value space of the lateral and longitudinal forces. The orientation of the ellipsoid indicates that longitudinal force allocation is more generous than lateral force allocation.

[0062] FIG. 4A illustrates cost function penalty 400 according to some examples. The diagram shows total force metric (e.g., F + Fy when applied to the value regions illustrated in FIG. 3A) on the horizontal axis (x-axis), and the applicable penalty on the vertical axis (y- axis). When the total force metric is below the value indicated by 415 (compare with 315 of FIG. 3A), the force allocation is within the first region (compare with 310 of FIG. 3A), and there is no increased cost function penalty; i.e., the cost function penalty 400 equals zero.When the total force metric is above the value indicated by 415 but below the value indicated by 425, the force allocation is within the second region (compare with 320 of FIG. 3A), and there is an increased cost function penalty compared to the first region. In this example, this is implemented by the cost function penalty 400 following a straight line from zero at 415 to a positive value at 425. When the total force metric is above the value indicated by 425 (compare with 325 of FIG. 3A), the force allocation is within the third region (compare with 340 of FIG. 3A), and the cost function penalty 400 is infinite (or equals a very high value).

[0063] FIG. 4B illustrates cost function penalty 400’ according to some examples. The diagram shows total force metric (e.g., F + Fy when applied to the value regions illustrated in FIG. 3B) on the horizontal axis (x-axis), and the applicable penalty on the vertical axis (y-axis). When the total force metric is below the value indicated by 415 (compare with 315 of FIG. 3B), the force allocation is within the first region, and there is no increased cost function penalty; i.e., the cost function penalty 400’ equals zero. When the total force metric is above the value indicated by 415 but below the value indicated by 435 (compare with 335 of FIG. 3B), the force allocation is within the low-valued sub-region of second region (compare with 320’ of FIG. 3B), and there is an increased cost function penalty compared to the first region. In this example, this is implemented by the cost function penalty 400’ following a straight line from zero at 415 to a first positive value at 435. When the total force metric is above the value indicated by 435 but below the value indicated by 425, the force allocation is within the high-valued sub-region of second region (compare with 330 of FIG. 3B), and there is an increased cost function penalty compared to the first region and compared to the low-valued sub-region of second region. In this example, this is implemented by the cost function penalty 400’ following a straight line from the first positive value at 435 to a second (higher) positive value at 425. When the total force metric is above the value indicated by 425 (compare with 325 of FIG. 3B), the force allocation is within the third region, and the cost function penalty 400’ is infinite (or equals a very high value).

[0064] FIG. 4C illustrates value regions of only longitudinal force, and a corresponding cost function penalty 400” according to some examples. The diagram shows the longitudinal force on the horizontal axis (x-axis), and the applicable penalty on the vertical axis (y-axis). For example, the diagram of FIG. 4C may be suitable to illustrate constraints on longitudinal force that can be applied when lateral force is already allocated (e.g., when lateral and longitudinal forces are, respectively, allocated by outer and inner control loops). Such a onedimensional approach is often easier to handle than a two-dimensional approach (e.g., due to the possibility to use linear - or affine - constraints on longitudinal force as opposed to nonlinear constraints for the two-dimensional case). This scenario may be illustrated by the dashed vertical line 351 in FIG. 3B; which moves along the horizontal axis of FIG. 3B as the value of the already allocated lateral force changes. This dashed vertical line 351 therefore represents longitudinal force values for a given lateral force.

[0065] In FIG. 4C, the first region corresponds to absolute values of the longitudinal force for which a first threshold condition is satisfied. The first threshold condition is represented by 416, and can be expressed as | Fx| < K . In relation to FIG. 3B, K =jC- — F . Within the first region, there is no increased cost function penalty; i.e., the costfunction penalty 400” equals zero. The third region corresponds to absolute values of the longitudinal force for which a second threshold condition is un-satisfied. The second threshold condition is represented by 426, and can be expressed as |FX| < K2. In relation to FIG. 3B, K2= / C2— F . Within the third region, the cost function penalty 400” is infinite (or equals a very high value).

[0066] A low-valued sub-region of the second region corresponds to absolute values of the longitudinal force for which the first threshold condition is un-satisfied and a further threshold condition is satisfied. The further threshold condition is represented by 436, and can be expressed as |FX| < K3. In relation to FIG. 3B, K3= ^ C3— F . Within the lowvalued sub-region of the second region, the cost function penalty 400” follows a straight line from zero at 416 to a first positive value at 436. A high-valued sub-region of the second region corresponds to absolute values of the longitudinal force for which the further threshold condition is un-satisfied and the second threshold condition is satisfied. Within the highvalued sub-region of the second region, the cost function penalty 400” follows a straight line from the first positive value at 436 to a second (higher) positive value at 426.

[0067] It should be noted that the value regions, threshold conditions, and cost function penalties illustrated in FIGs. 3A, 3B, 3C, 4A, 4B, and 4C are merely examples, and that any suitable value regions, threshold conditions, and cost function penalties may be used.

[0068] For example, the threshold conditions do not necessarily have to form a circle or an ellipsoid in the value space of the lateral and longitudinal forces, but may correspond to any other suitable geometric form, such as a rhombic form, a rectangular form, etc. In some examples, an approximation of a circle (or an ellipsoid) may be applied, where a plurality of piecewise linear - or affine - segments are used to collectively form a shape resembling the circle (or the ellipsoid); e.g., a - typically equilateral - polygon. Using six segments would correspond to a hexagon, using eight segments would correspond to an octagon, etc. Such an approach allows the use of a plurality of linear - affine - constraints (one per segment) instead of non-linear constraints (e.g., Fx2+ Fy < C), which typically decreases computational complexity.

[0069] Alternatively or additionally, the threshold conditions do not necessarily have to have the same form. For example, the first threshold condition may form an ellipsoid, while the second threshold condition forms a circle.

[0070] Yet alternatively or additionally, the cost function penalty for the second region does not necessarily have to be formed by a straight line (or a collection of connected straight lines) from zero at the boundary towards the first region to some positive value at the boundary towards the third region. For example, the cost function penalty for the second region could have a constant (positive) value, or be formed by any suitable function increasing from a first (non-negative) value at the boundary towards the first region to a second (higher) value at the boundary towards the third region (e.g., an exponential function, a polynomial function - such as a quadratic function, etc.).

[0071] As already mentioned, one or more of the (first, second, further) threshold conditions may typically be based on an estimation uncertainty for a parameter value that is used as input to the force allocation (e.g., tire-road friction and / or normal load Fz). Normally, the force allocation might be based on only the estimated parameter values as illustrated by 350 in FIG. 3B (e.g., having default force allocation when Fx2+ Fy < ( / / ■ Fz)2and un-allowed force allocation otherwise), while the at least three regions may be introduced by considering also lower and / or upper bounds for the estimated parameter values. For example, the upper and lower bounds may correspond to some percentile of probability that the actual parameter value falls, respectively, below the lower bound and above the upper bound.

[0072] For example, the first threshold condition may be based on a lower bound associated with the estimation uncertainty (e.g., a lower bound for the estimation uncertainty of tire-road friction and / or a lower bound for the estimation uncertainty of normal load Fz). In some examples, the lower bound associated with the estimation uncertainty corresponds to a parameter value with a specific probability of exceeding that value, given the parameter estimation. Referring to the examples of FIGs. 3A and 3B, this corresponds to= / I(F< FZ), whererepresents some suitable function; e.g.,= ( ■ Fz)2.

[0073] Alternatively or additionally, the second threshold condition may be based on an upper bound associated with the estimation uncertainty (e.g., an upper bound for the estimation uncertainty of tire-road friction and / or an upper bound for the estimation uncertainty of normal load Fz). In some examples, the upper bound associated with the estimation uncertainty corresponds to a parameter value with a specific probability of exceeding that value, given the parameter estimation. Referring to the examples of FIGs. 3Aand 3B, this corresponds to C2= f2( i, Fz), where f2represents some suitable function; e.g.,

[0074] Yet alternatively or additionally, each of the further threshold condition(s) may be based on the lower or upper bounds associated with the estimation uncertainty.

[0075] Alternatively or additionally to being based on a parameter estimation uncertainty, one or more of the (first, second, further) threshold conditions may be based on one or more additional variables (termed slack variables) for tuning the restricted force allocation of the second region (adapting the boundaries of the second region and its sub-regions, when applicable). For example, referring to FIG. 3B, and using three slack variables y15y2, y3which are all > 0, the first threshold condition 315 may be expressed as Fj + Fy — y2< (y3■ ■ Fz)2, the second threshold condition 325 may be expressed as Fx2+ Fy < (Ji - Fz)2, and the further threshold condition 335 may be expressed as Fj + Fy — y < ( ■ Fz)2.Typically, y3< 1 acts as a safety margin. Also typically, y2< yx.

[0076] The slack variables may also be used to define the cost function penalty. For example (compare with FIG. 4B), when a low-valued sub-region (415-435) of the second region has a first-order polynomial function defining the cost function penalty and a highvalued sub-region (435-425) of the second region has a second-order polynomial function defining the cost function penalty, the cost function penalty can be expressed as cost2y2+ cos^y2, where cost-L > 0 and cost2> 0 represent tuning parameters.

[0077] Generally, the principles described herein may be applied in any suitable context of force allocation for a vehicle. They may be particularly suitable for situations when a control allocator solves an optimization problem (e.g., minimizing power losses, etc.) via a cost function, in which situations the constraints on lateral and / or longitudinal forces may be applied as part of the optimization problem.

[0078] For example, a default optimization problem can be expressed as min cost(u) u subject to u < u < u, Bu = v, and G(u) < h, where it, u, u represents actuator instructions and actuator capacity limits, v represents motion requests, B represents a linear transform function, and G(u) < h represents force limitations (e.g., per axle and / or per wheel) to be applied when transforming the motion requests to the actuator instructions. Then, the constraints on lateral and / or longitudinal forces as suggested herein may be applied by usingthe at least three regions in place of G(u) < h and letting the cost function cost(u) have the increased penalty in the second region.

[0079] FIG. 5 schematically illustrates a control apparatus 500 according to some examples. The control apparatus 500 may be comprised in computer system 510 for controlling a vehicle (e.g., the vehicle 200 of FIG. 2). For example, the control apparatus 500 may be comprised in the VCU 290 of FIG. 2. Alternatively or additionally, the control apparatus 500 may be configured to cause execution of (e.g., may be configured to perform) one or more steps of the method 100 of FIG. 1.

[0080] The control apparatus 500 comprises a controller (CNTR; e.g., control circuitry or a control module) 520; e.g., in the form of processing circuitry.

[0081] The controller 520 is configured to cause application of constraints on lateral and / or longitudinal forces as a part of transforming motion requests to actuator instructions, wherein the constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces as described and exemplified herein.

[0082] To this end, the controller 520 may comprise, or be otherwise associated with (e.g., connected, or connectable, to) a constraint applier (CONS; e.g., constraint applying circuitry, or a constraint application module) 522, which may be configured to apply the constraints.

[0083] FIG. 6 schematically illustrates functionality 600 for actuation control of a wheel 610 according to some examples. The control of the wheel 610 is performed via some example motion support devices (MSDs) 620; here comprising a propulsion device (PR) 621, such as an electric machine (EM) and a power steering arrangement (ST) 622. A power steering arrangement and a propulsion device are examples of actuators which can be controlled by one or more MSD control units. It should be noted that any suitable actuator(s) may be used as MSD(s), and that FIG. 6 only represents an example of MSDs. Other examples include various types of brakes.

[0084] A vehicle motion management (VMM) function 630 may be employed to perform force allocation to meet received motion requests (REQ) 640 in a safe and robust manner. The VMM function 630 communicates actuator instructions to the different MSDs via the MDS control units. The VMM function 630 manages both force generation and MSD coordination; i.e., it determines what forces that are required for different wheels and vehicle units in order to fulfil the motion requests 640, for instance to accelerate the vehicleaccording to a requested acceleration profile and / or to generate a requested curvature motion by the vehicle.

[0085] For example, the VMM function 630 may be comprised in the VCU 290 of FIG. 2. Alternatively or additionally, the VMM function 630 may be configured to cause execution of (e.g., may be configured to perform) one or more steps of the method 100 of FIG. 1. Yet alternatively or additionally, the VMM function 630 may comprise the control apparatus 500 of FIG. 5

[0086] The VMM function 630 is configured to apply constraints on lateral and / or longitudinal forces as a part of transforming motion requests to actuator instructions, wherein the constraints correspond to two or more threshold conditions defining value regions of lateral and / or longitudinal forces as described and exemplified herein. To this end the VMM function 630 has access to estimated values of one or more parameters (e.g., tire-road friction and / or normal load) and corresponding uncertainty information. For example, the parameter information may be received from another functional unit of the vehicle, or may be determined by the VMM function 630 function itself (e.g., based on sensor data).

[0087] In some examples, the VMM function 630 may comprise a control allocator (CA) 631 for transforming the motion requests to actuator instructions, and the control allocator 631 may be configured to apply the constraints.

[0088] FIG. 7 is a schematic diagram of a computer system 700 for implementing examples disclosed herein. For example, the computer system 700 (or part thereof) may be comprised in the VCU 290 of FIG. 2. Alternatively or additionally, the computer system 700 may be configured to cause execution of (e.g., may be configured to perform) one or more steps of the method 100 of FIG. 1. Yet alternatively or additionally, the computer system 700 may comprise the control apparatus 500 of FIG. 5. Yet alternatively or additionally, the computer system 700 may be configured to implement the VMM function 630 of FIG. 6.

[0089] The computer system 700 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 700 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 700 may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any oneor 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.

[0090] The computer system 700 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 700 may include processing circuitry 702 (e.g., processing circuitry including one or more processor devices or control units), a memory 704, and a system bus 706. The computer system 700 may include at least one computing device having the processing circuitry 702. The system bus 706 provides an interface for system components including, but not limited to, the memory 704 and the processing circuitry 702. The processing circuitry 702 may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory 704. The processing circuitry 702 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 702 may further include computer executable code that controls operation of the programmable device.

[0091] The system bus 706 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 704 may be one or more devices for storing data and / or computer code for completing or facilitating methodsdescribed herein. The memory 704 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 704 may be communicably connected to the processing circuitry 702 (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 704 may include non-volatile memory 708 (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory 710 (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 702. A basic input / output system (BIOS) 712 may be stored in the non-volatile memory 708 and can include the basic routines that help to transfer information between elements within the computer system 700.

[0092] The computer system 700 may further include or be coupled to a non-transitory computer-readable storage medium such as the storage device 714, 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 714 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.

[0093] 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 be stored in the storage device 714 and / or in the volatile memory 710, which may include an operating system 716 and / or one or more program modules 718. All or a portion of the examples disclosed herein may be implemented as a computer program 720 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 714, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the processing circuitry 702 to carry out actions described herein. Thus, the computer-readableprogram code of the computer program 720 can comprise software instructions for implementing the functionality of the examples described herein when executed by the processing circuitry 702. In some examples, the storage device 714 may be a computer program product (e.g., readable storage medium) storing the computer program 720 thereon, where at least a portion of a computer program 720 may be loadable (e.g., into a processor) for implementing the functionality of the examples described herein when executed by the processing circuitry 702. The processing circuitry 702 may serve as a controller or control system for the computer system 700 that is to implement the functionality described herein.

[0094] The computer system 700 may include an input device interface 722 configured to receive input and selections to be communicated to the computer system 700 when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processing circuitry 702 through the input device interface 722 coupled to the system bus 706 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 700 may include an output device interface 724 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 700 may include a communications interface 726 suitable for communicating with a network as appropriate or desired.

[0095] 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 the actions may differ. In addition, two or more actions may be performed concurrently or with partial concurrence.

[0096] The described examples and their equivalents may be realized in software or hardware or a combination thereof. The examples may be performed by general purpose circuitry. Examples of general purpose circuitry include digital signal processors (DSP), central processing units (CPU), co-processor units, field programmable gate arrays (FPGA) and other programmable hardware. Alternatively or additionally, the examples may be performed by specialized circuitry, such as application specific integrated circuits (ASIC).The general purpose circuitry and / or the specialized circuitry may, for example, be associated with or comprised in an electronic apparatus such as a VCU.

[0097] The electronic apparatus may comprise arrangements, circuitry, and / or logic according to any of the examples described herein. Alternatively or additionally, the electronic apparatus may be configured to perform method steps according to any of the examples described herein.

[0098] According to some examples, a computer program product comprises a non- transitory computer readable medium such as, for example, a universal serial bus (USB) memory, a plug-in card, an embedded drive, or a read only memory (ROM). FIG. 8 illustrates a computer program product exemplified as a non-transitory computer-readable medium in the form of a compact disc (CD) ROM 800. The computer-readable medium has stored thereon program code 840 comprising instructions. The program code is loadable into processing circuitry (PROC; e.g., a data processing unit) 820, which may, for example, be comprised in a VCU 810. When loaded into the processing circuitry, the program code may be stored in a memory (MEM) 830 associated with, or comprised in, the processing circuitry. According to some examples, the program code may, when loaded into, and run by, the processing circuitry, cause execution of method steps according to, for example, any of the methods described herein.

[0099] FIG. 9 schematically illustrates, in terms of a number of functional units, the components of a control unit 900 according to some examples. This control unit 900 may be comprised in the vehicle 200; e.g., in the form of a VCU 290. Processing circuitry 910 is provided using any combination of one or more of a suitable central processing unit CPU, multiprocessor, microcontroller, digital signal processor DSP, etc., capable of executing software instructions stored in a computer program product, e.g. in the form of a storage medium 930. The processing circuitry 910 may further be provided as at least one application specific integrated circuit ASIC, or field programmable gate array FPGA.

[0100] Particularly, the processing circuitry 910 is configured to cause the control unit 900 to perform a set of operations, or steps, such as the method discussed in connection to FIG. 1

[0101] Consequently, there is disclosed herein a control unit 900 for controlling a heavy- duty vehicle 200 to enforce limitation on longitudinal slip as described herein.

[0102] For example, the storage medium 930 may store the set of operations, and the processing circuitry 910 may be configured to retrieve the set of operations from the storage medium 930 to cause the control unit 900 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 910 is thereby arranged to execute methods as herein disclosed. In particular, there is disclosed a control unit 900 for controlling an articulated vehicle 200 comprising a tractor 210 and / or one or more towed vehicle units 211, 212, the control unit comprising processing circuitry 910, an interface 920 coupled to the processing circuitry 910, and a memory 930 coupled to the processing circuitry 910, wherein the memory comprises machine readable computer program instructions that, when executed by the processing circuitry, causes the control unit to perform the methods discussed herein.

[0103] The storage medium 930 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0104] The control unit 900 may further comprise an interface 920 for communications with at least one external device. As such, the interface 920 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of ports for wireline or wireless communication.

[0105] The processing circuitry 910 controls the general operation of the control unit 900, e.g., by sending data and control signals to the interface 920 and the storage medium 930, by receiving data and reports from the interface 920, and by retrieving data and instructions from the storage medium 930. Other components, as well as the related functionality, of the control node are omitted in order not to obscure the concepts presented herein.A non-exhaustive list of examples:

[0106] Example 1: A computer system configured for controlling a vehicle, wherein the vehicle comprises a plurality of motion support devices for actuating the vehicle and a control allocator for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions, the computer system comprising processing circuitry configured to apply constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuator instructions, wherein the constraintscorrespond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces, the regions including at least: a first region corresponding to values of the lateral and / or longitudinal forces for which a first threshold condition is satisfied, wherein the first region is associated with default force allocation, a second region corresponding to values of the lateral and / or longitudinal forces for which a second threshold condition is satisfied and for which the first threshold condition is unsatisfied, wherein the second region is associated with restricted force allocation, and a third region corresponding to values of the lateral and / or longitudinal forces for which the first and second threshold conditions are unsatisfied, wherein the third region is associated with un-allowed force allocation.

[0107] Example 2: The computer system of Example 1, wherein the constraints on lateral and / or longitudinal forces comprise respective constraints on lateral and / or longitudinal forces for each of one or more wheel(s) of the vehicle, or respective constraints on lateral and / or longitudinal forces for each of one or more wheel combination(s) of the vehicle.

[0108] Example 3: The computer system of any of Examples 1-2, wherein the second region comprises two or more sub-regions defined by one or more further threshold condition(s), wherein different sub-regions are associated with different restrictions of the force allocation.

[0109] Example 4: The computer system of any of Examples 1-3, wherein each of the threshold conditions forms a circle, or an ellipsoid, or a polygon in a value space of the lateral and / or longitudinal forces.

[0110] Example 5: The computer system of any of Examples 1-4, wherein the restricted force allocation is implemented by application of increased penalty in a cost function.

[0111] Example 6: The computer system of Example 5, wherein the penalty increases with increasing values of the lateral and / or longitudinal forces in the second region.

[0112] Example 7: The computer system of any of Examples 1-6, wherein at least one of the threshold conditions is based on an estimation uncertainty for tire-road friction and / or normal load.

[0113] Example 8: The computer system of Example 7, wherein the first threshold condition is based on a lower bound associated with the estimation uncertainty.

[0114] Example 9: The computer system of Example 8, wherein the first threshold condition is further based on one or more slack variable(s) for tuning the restricted force allocation.

[0115] Example 10: The computer system of any of Examples 7-9, wherein the second threshold condition is based on an upper bound associated with the estimation uncertainty.

[0116] Example 11: The computer system of any of Examples 7-10, wherein at least one of the threshold conditions corresponds to a specific probability that the actual tire-road friction and / or normal load exceeds a threshold value, given currently estimated tire-road friction and / or normal load.

[0117] Example 12: A computer-implemented method for controlling a vehicle, wherein the vehicle comprises a plurality of motion support devices for actuating the vehicle and a control allocator for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions, the method comprising applying, by processing circuitry of a computer system, constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuator instructions, wherein the constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces, the regions including at least: a first region corresponding to values of the lateral and / or longitudinal forces for which a first threshold condition is satisfied, wherein the first region is associated with default force allocation, a second region corresponding to values of the lateral and / or longitudinal forces for which a second threshold condition is satisfied and for which the first threshold condition is unsatisfied, wherein the second region is associated with restricted force allocation, and a third region corresponding to values of the lateral and / or longitudinal forces for which the first and second threshold conditions are unsatisfied, wherein the third region is associated with un-allowed force allocation.

[0118] Example 13: The method of Example 12, wherein the constraints on lateral and / or longitudinal forces comprise respective constraints on lateral and / or longitudinal forces for each of one or more wheel(s) of the vehicle, or respective constraints on lateral and / or longitudinal forces for each of one or more wheel combination(s) of the vehicle.

[0119] Example 14: The method of any of Examples 12-13, wherein the second region comprises two or more sub-regions defined by one or more further threshold condition(s), wherein different sub-regions are associated with different restrictions of the force allocation.

[0120] Example 15: The method of any of Examples 12-14, wherein each of the threshold conditions forms a circle, or an ellipsoid, or a polygon in a value space of the lateral and / or longitudinal forces.

[0121] Example 16: The method of any of Examples 12-15, wherein the restricted force allocation is implemented by application of increased penalty in a cost function.

[0122] Example 17: The method of Example 16, wherein the penalty increases with increasing values of the lateral and / or longitudinal forces in the second region.

[0123] Example 18: The method of any of Examples 12-17, wherein at least one of the threshold conditions is based on an estimation uncertainty for tire-road friction and / or normal load.

[0124] Example 19: The method of Example 18, wherein the first threshold condition is based on a lower bound associated with the estimation uncertainty.

[0125] Example 20: The method of Example 19, wherein the first threshold condition is further based on one or more slack variable(s) for tuning the restricted force allocation.

[0126] Example 21: The method of any of Examples 18-20, wherein the second threshold condition is based on an upper bound associated with the estimation uncertainty.

[0127] Example 22: The method of any of Examples 18-21, wherein at least one of the threshold conditions corresponds to a specific probability that the actual tire-road friction and / or normal load exceeds a threshold value, given currently estimated tire-road friction and / or normal load.

[0128] Example 23: A vehicle comprising the computer system of any of Examples 1-11 and / or processing circuitry configured to perform the method of any of Examples 12-22.

[0129] Example 24: A computer program product comprising program code for performing, when executed by processing circuitry, the method of any of Examples 12-22.

[0130] Example 25: A non-transitory computer-readable storage medium comprising instructions, which when executed by processing circuitry, cause the processing circuitry to perform the method of any of Examples 12-22.

[0131] 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 ofone 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.

[0132] 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.

[0133] 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.

[0134] 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 this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0135] Reference has been made herein to various examples. However, a person skilled in the art would recognize numerous variations to the described examples that would still fall within the scope of the claims.

[0136] For example, the methods described herein discloses example methods through steps being performed in a certain order. However, it is recognized that these sequences of events may take place in another order without departing from the scope of the claims. Furthermore, some method steps may be performed in parallel even though they have beendescribed as being performed in sequence. Thus, the steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step.

[0137] In the same manner, it should be noted that the partition of functional blocks into particular units is by no means intended as limiting. Contrarily, these partitions are merely examples. Functional blocks described herein as one unit may be split into two or more units. Furthermore, functional blocks described herein as being implemented as two or more units may be merged into fewer (e.g. a single) unit.

[0138] Any feature of any of the examples disclosed herein may be applied to any other example, wherever suitable. Likewise, any advantage of any of the examples may apply to any other examples.

[0139] 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.

Claims

ClaimsWhat is claimed is:

1. A computer system (700) configured for controlling a vehicle (200), wherein the vehicle comprises a plurality of motion support devices (620) for actuating the vehicle and a control allocator (631) for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions, the computer system comprising processing circuitry configured to: apply constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuator instructions, wherein the constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces, the regions including at least: a first region (310) corresponding to values of the lateral and / or longitudinal forces for which a first threshold condition (315, 415, 416) is satisfied, wherein the first region is associated with default force allocation; a second region (320, 320’, 330) corresponding to values of the lateral and / or longitudinal forces for which a second threshold condition (325, 425, 426) is satisfied and for which the first threshold condition is unsatisfied, wherein the second region is associated with restricted force allocation; and a third region (340) corresponding to values of the lateral and / or longitudinal forces for which the first and second threshold conditions are unsatisfied, wherein the third region is associated with un-allowed force allocation.

2. A computer-implemented method (100) for controlling a vehicle (200), wherein the vehicle comprises a plurality of motion support devices (620) for actuating the vehicle and a control allocator (631) for transforming motion requests to actuator instructions, and wherein the vehicle is configured to respond to the motion requests by operating the plurality of motion support devices in response to the actuator instructions, the method comprising: applying (120), by processing circuitry of a computer system, constraints on lateral and / or longitudinal forces as a part of transforming the motion requests to the actuatorinstructions, wherein the constraints correspond to two or more threshold conditions defining value regions of the lateral and / or longitudinal forces, the regions including at least: a first region (310) corresponding to values of the lateral and / or longitudinal forces for which a first threshold condition (315, 415, 416) is satisfied, wherein the first region is associated with default force allocation; a second region (320, 320’, 330) corresponding to values of the lateral and / or longitudinal forces for which a second threshold condition (325, 425, 426) is satisfied and for which the first threshold condition is unsatisfied, wherein the second region is associated with restricted force allocation; and a third region (340) corresponding to values of the lateral and / or longitudinal forces for which the first and second threshold conditions are unsatisfied, wherein the third region is associated with un-allowed force allocation.

3. The method of claim 2, wherein the constraints on lateral and / or longitudinal forces comprise respective constraints on lateral and / or longitudinal forces for each of one or more wheel(s) (610) of the vehicle, or respective constraints on lateral and / or longitudinal forces for each of one or more wheel combination(s) of the vehicle.

4. The method of any of claims 2-3, wherein the second region comprises two or more sub-regions (320’, 330) defined by one or more further threshold condition(s) (335, 435, 436), wherein different sub-regions are associated with different restrictions of the force allocation.

5. The method of any of claims 2-4, wherein each of the threshold conditions forms a circle, or an ellipsoid, or a polygon in a value space of the lateral and / or longitudinal forces.

6. The method of any of claims 2-5, wherein the restricted force allocation is implemented by application of increased penalty (400, 400’, 400”) in a cost function.

7. The method of claim 6, wherein the penalty increases with increasing values of the lateral and / or longitudinal forces in the second region.

8. The method of any of claims 2-7, wherein at least one of the threshold conditions is based on an estimation uncertainty for tire-road friction and / or normal load.

9. The method of claim 8, wherein the first threshold condition is based on a lower bound associated with the estimation uncertainty.

10. The method of claim 9, wherein the first threshold condition is further based on one or more slack variable(s) for tuning the restricted force allocation.

11. The method of any of claims 8-10, wherein the second threshold condition is based on an upper bound associated with the estimation uncertainty.

12. The method of any of claims 8-11, wherein at least one of the threshold conditions corresponds to a specific probability that the actual tire-road friction and / or normal load exceeds a threshold value, given currently estimated tire-road friction and / or normal load.

13. A vehicle (200) comprising the computer system of claim 1 and / or processing circuitry configured to perform the method of any of claims 2-12.

14. A computer program product (800) comprising program code for performing, when executed by processing circuitry, the method of any of claims 2-12.

15. A non-transitory computer-readable storage medium (800) comprising instructions, which when executed by processing circuitry, cause the processing circuitry to perform the method of any of claims 2-12.

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