Vehicle motion management with redundant wheel control safety net functionality

Abstract

Vehicle motion management with a redundant wheel control safety net function is provided, in particular a motion support device, MSD, control unit for a heavy vehicle, the control unit being configured to control one or more MSDs associated with wheels on the vehicle, the MSD control unit being arranged to be communicatively coupled to a vehicle motion management, VMM, unit for receiving control commands including wheel speed requests and / or wheel slip requests from the VMM unit to control vehicle motion by the one or more MSDs, the MSD control unit being arranged to obtain a capability range indicative of a range of wheel behavior for which the VMM unit is allowed to influence the behavior of the wheels by the control commands, and the MSD control unit being arranged to monitor wheel behavior and detect whether the wheel behavior is outside the capability range, the MSD control unit being arranged to trigger a control intervention function if the monitored wheel behavior is outside the capability range.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to vehicle motion management for heavy-duty vehicles, i.e. coordinated control of motion support devices such as service brakes and propulsion devices.

[0002] The present invention can be applied to heavy-duty vehicles such as trucks, buses, construction machines etc. Although the invention will mainly be described with respect to goods transport vehicles such as semi-trailers and trucks, the invention is not limited to this particular type of vehicle but can also be used in other types of vehicles, e.g. passenger cars. BACKGROUND

[0003] Vehicles are becoming more and more complex in terms of mechanics, pneumatics, hydraulics, electronics and software. A modern heavy-duty vehicle, e.g. a semi-trailer truck, can comprise a variety of different physical devices such as internal combustion engines, electric machines, friction brakes, regenerative brakes, shock absorbers, air bellows and power steering pumps. These physical devices are often referred to as motion support devices (MSD). The MSDs can be independently controllable, e.g. a friction brake (i.e. a negative torque) can be applied on one wheel while another wheel on the vehicle, possibly even on the same axle, is simultaneously used to generate a positive torque by an electric machine.

[0004] Recently proposed vehicle motion management (VMM) functions, e.g. executed on a central vehicle unit computer (VUC), rely on combinations of MSDs to operate the vehicle to obtain a desired motion effect while maintaining vehicle stability, cost efficiency and safety. One such example is disclosed in WO2019072379A1 where wheel brakes are selectively used to assist a turning operation of a heavy-duty vehicle. The VMM control can advantageously be based on wheel speed requests or wheel slip requests sent from the VMM to MSD control units that control the various MSDs through low-latency-high-bandwidth control loops that aim to keep the wheel behaviour as close as possible to the requested wheel slip value or wheel speed value.

[0005] Due at least partly to the complexity inherent in these advanced wheel speed or wheel slip based motion management functions, it can be a challenge to verify the overall system functionality according to traditional safety standards. There is a need for methods and control architectures that can prevent these advanced motion management functions from inadvertently locking wheels and / or introducing undesired yaw motion of the vehicle. SUMMARY

[0006] It is an object of the present disclosure to provide an improved vehicle control unit, method and function that fulfils the safety requirements for heavy vehicles. This object is at least partly achieved by a motion support device (MSD) control unit for a heavy vehicle. The MSD control unit is configured to control one or more MSDs associated with at least one wheel on the vehicle, i.e. the control unit disclosed herein can be configured to control a single wheel on the vehicle, or control two wheels on an axle of the vehicle, or control all wheels on certain parts of the vehicle. The MSD control unit is arranged in communicative coupling to a vehicle motion management (VMM) unit for receiving control commands comprising wheel speed requests and / or wheel slip requests from the VMM unit for controlling vehicle motion by the one or more MSDs. The MSD control unit is arranged to obtain a capability range indicative of a wheel behaviour range of the wheel for which the VMM unit is allowed to influence the behaviour of the wheel by said control commands. The MSD control unit is further arranged to monitor the wheel behaviour and detect whether the wheel behaviour is outside said capability range, wherein the MSD control unit is arranged to trigger a control intervention function in case the monitored wheel behaviour is outside said capability range.

[0007] This means that the VMM is free to control the at least one wheel as long as the resulting wheel behaviour is within said capability range. But as soon as the wheel behaviour deviates from said capability range, said MSD control unit triggers said control intervention function. Thus, due to this safety net achieved by said capability range and said control intervention function, the traditional safety standards are still fulfilled. In this way, more advanced functions can be introduced in the vehicle without extensive testing and verification being necessary if the traditional safety mechanisms are not intact. By some small modifications of the existing communication signals and special considerations in the VMM related to the allocation of wheel speed requests, the traditional anti-lock braking function as well as the traction control function and the stability control function that exist in today's brake systems can be re-used to provide this safety net.

[0008] The one or more MSDs can for example comprise at least one service brake arranged to generate negative torque by the wheel and at least one propulsion unit arranged to generate positive and / or negative torque by the wheel. Thus, the proposed control unit is suitable for controlling and coordinating both said propulsion devices and the wheel brakes, which is an advantage.

[0009] According to some aspects, the capability range comprises an upper limit and / or a lower limit of allowed positive longitudinal wheel slip and / or negative longitudinal wheel slip and / or wheel rotational speed. This means that if the VMM control results in wheel behaviour that leads to wheel slip outside acceptable values, a safety net function steps in. The acceptable values can for example correspond to wheel slip values that result in an approximately linear relationship between tyre force and wheel slip. The capability range can also comprise an upper limit and / or a lower limit of allowed positive longitudinal wheel acceleration and / or negative longitudinal wheel acceleration, and an upper limit and / or a lower limit of allowed positive vehicle yaw rate and / or negative vehicle yaw rate. Thus, the vehicle control unit discussed herein defines a capability range based on any of wheel slip, wheel speed, wheel acceleration and / or yaw rate. As long as the wheel behaviour remains within the boundaries set by this capability range, the VMM is allowed to control the wheel behaviour. However, if the wheel behaviour deviates from the currently set capability range, countermeasures are taken to ensure safe vehicle manoeuvring.

[0010] According to some aspects, the MSD control unit is arranged to receive wheel speed data associated with a wheel from a wheel speed sensor, and to detect whether the wheel behaviour is outside the capability range based on this wheel speed data. To some extent, wheel speed, wheel acceleration and wheel slip are all measures of the same wheel behaviour, and can be used interchangeably.

[0011] According to some aspects, the MSD control unit is arranged to obtain a fixed capability range as a parameter loaded from memory or received from an external configuration entity. This fixed capability range can be programmed depending on e.g. traditional vehicle safety standards or safety verification tests. However, the MSD control unit can also be arranged to continuously obtain an updated capability range. This updated capability range can be dynamically configured depending on e.g. vehicle type, vehicle transport task or other parameters such as driving conditions. For example, driving conditions and / or transport task can e.g. warrant an increased safety margin.

[0012] According to some aspects, the control intervention function comprises an intervention function performed by one or more MSDs. Such intervention functions can for example comprise an anti-lock function, a traction control function, etc.

[0013] According to some aspects, the control intervention function comprises triggering a request to an external arbitrator function for direct MSD control by the MSD control unit. This allows arbitration between multiple conflicting requests. For example, it can be the case that the consequences of not allowing VMM control in certain scenarios are worse than allowing the VMM to complete execution of e.g. an ongoing emergency operation.

[0014] According to some aspects, the MSD control unit is arranged to monitor the wheel behaviour by filtering samples of the wheel behaviour over time, and to detect whether the wheel behaviour is outside the capability range based on the result of the filtering. This allows to suppress false excursions from the capability range, which can be caused by measurement errors and / or transient effects that do not warrant triggering an intervention function.

[0015] The object is also achieved by a Vehicle Motion Management (VMM) unit arranged to perform vehicle motion management to control the motion of a heavy vehicle by one or more Motion Support Devices (MSD) associated with at least one wheel on the vehicle.

[0016] The VMM unit is arranged to be communicatively coupled to the MSD control unit for sending control commands comprising wheel speed requests and / or wheel slip requests to the MSD control unit to control the vehicle motion by the one or more MSDs, wherein the VMM unit is arranged to obtain a capability range indicative of a range of wheel behaviour of the wheel for which the VMM unit is allowed to influence the behaviour of the wheel by the control commands, and wherein the VMM unit is arranged to generate the control commands such that the wheel behaviour is within the capability range.

[0017] Hence, as mentioned above, the VMM unit is allowed more freedom to control the one or more wheels as long as the resulting behaviour remains within the obtained capability range. The VMM unit is configured to control the vehicle without generating control commands that result in wheel behaviour that deviates from the capability range. Hence, the capability range indirectly influences vehicle control, such as force distribution and trajectory planning. For example, a more strict limit on wheel slip can influence vehicle motion management such that a less aggressive trajectory is chosen. On the other hand, a more relaxed capability range can allow for more aggressive vehicle motion management control associated with higher wheel slip and / or higher yaw rate.

[0018] According to some aspects, the VMM unit comprises an arbitrator function configured to receive requests for direct MSD control by the MSD control unit, and to yield vehicle control to the MSD control unit in case the wheel behaviour is outside a predetermined wheel behaviour safety range. The arbitrator function can be configured to arbitrate between a desired VMM control objective and allowing the MSD control unit to intervene. This way, occasional excursions of the wheel behaviour can be tolerated in some situations where it is deemed that yielding control to the MSD control unit would be worse. For example, this can be the case if an emergency evasion operation is being performed to avoid an obstacle, in which case a slightly higher wheel slip can be temporarily allowed.

[0019] Also disclosed herein are computer programs, computer readable media, computer program products and vehicles associated with the above advantages.

[0020] In general, all terms used herein are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined herein. All references to a / an / the [element, device, component, means, step, etc.] are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed unless explicitly stated. Further features and advantages of the present application will become apparent from studying the appended claims and the following description. Those skilled in the art will recognize that the present application can be embodied in many different forms and taken into account the possibility of combining different features in other embodiments not explicitly described. BRIEF DESCRIPTION OF DRAWINGS

[0021] With reference to the appended drawings, below follows a more detailed description of embodiments of the application cited as examples.

[0022] In these drawings:

[0023] Figure 1 An example heavy vehicle is shown;

[0024] Figure 2 A motion support arrangement is schematically shown;

[0025] Figure 3 is a graph showing tire forces as a function of wheel slip;

[0026] Figure 4 A capability range is schematically shown;

[0027] Figures 5 to 6 An example motion support control system is shown;

[0028] Figure 7 is a flow chart illustrating a method;

[0029] Figure 8 A control unit is schematically shown; and

[0030] Figure 9 An example computer program product is shown. DETAILED DESCRIPTION

[0031] The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the application are shown. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. Like reference numerals refer to like elements throughout the specification.

[0032] It should be understood that the application is not limited to the embodiments described and shown herein; rather, persons skilled in the art will recognize that many modifications and variations of the present application can be made without departing from the scope of the appended claims.

[0033] Figure 1 An example vehicle 100 for goods transport is shown, in which the technology disclosed herein can be advantageously applied. The vehicle 100 comprises a trailer or tractor vehicle 110 supported on front wheels 150 and rear wheels 160, at least some of which are drive wheels. The trailer 110 is configured to tow a first trailer unit 120 in a known manner, which is supported on trailer wheels 170 by fifth wheel connections. These trailer wheels are typically brake wheels, but can also comprise drive wheels on one or more axles.

[0034] The trailer 110 comprises a vehicle unit computer (VUC) 130 for controlling various functions, i.e. enabling propulsion, braking and steering. Some trailer units 120 also comprise a VUC 140 for controlling various functions of the trailer, such as braking of the trailer wheels, and sometimes also propulsion of the trailer wheels. The VUCs 130, 140 can be centralized, or distributed over several processing circuits. Parts of the vehicle control functions can also be performed remotely, e.g. on a remote server 190 connected to the vehicle 100 via a wireless link 180 and a wireless access network 185.

[0035] The VUC 130 on the tractor 110 (and possibly also the VUC 140 on the trailer 120) can be configured to execute a vehicle control method organized according to a hierarchical functional architecture, in which some functions can be included in a Traffic Situation Management (TSM) domain in a higher layer, while some other functions can be included in a Vehicle Motion Management (VMM) domain in a lower functional layer. The TSM plans the driving operation in a time horizon of, for example, 10 seconds. This time horizon corresponds to, for example, the time it takes for the vehicle 100 to cross a curve. The vehicle maneuvers planned and executed by the TSM can be associated with acceleration profiles and curvature profiles. The TSM constantly requests the desired acceleration profiles and curvature profiles to the VMM function, which performs the allocation of forces in order to fulfill the requests from the TSM in a safe and robust way.

[0036] The VMM operates in a time horizon of about 1 second or so, and constantly translates the acceleration profiles and curvature profiles into control commands for controlling the vehicle motion functions actuated by the different MSDs of the vehicle. If the vehicle is in motion, the VMM performs motion estimation, i.e. determines the position, velocity, acceleration, articulation angles of the different units in the vehicle combination by monitoring the operation using various sensors arranged on the vehicle, typically associated with the MSDs. For example, by determining the vehicle unit motion using, for example, global positioning system, radar sensors and / or lidar sensors and translating this vehicle unit motion into a local coordinate system of a given wheel, wheel slip can be accurately estimated by comparing the vehicle unit motion in the wheel reference coordinate system with data obtained from a wheel speed sensor connected to the wheel. The tire model discussed in more detail below can be used to translate between the desired tire forces and the wheel slip. Figure 3

[0037] The VMM also manages the generation and coordination of forces, i.e. it determines what forces are needed to fulfill the requests from the TSM, such as accelerating the vehicle according to a requested acceleration profile requested by the TSM and / or generating a specific curvature motion of the vehicle also requested by the TSM. These forces can include, for example, longitudinal and lateral forces, as well as different types of torques.

[0038] Conventionally, the interface between the VMM and the MSDs capable of delivering torques to the wheels of the vehicle has been focused on torque-based requests from the VMM to each MSD. However, by instead using wheel speed or wheel slip based requests, significant benefits can be obtained - shifting the difficult actuator speed control loop to the MSD controllers, which typically operate with much shorter sampling times than the VMM. This architecture can provide better disturbance rejection and can improve the predictability of the forces generated at the tire road contact surface compared to a torque-based control interface. ​

[0039] While the wheel speed (or wheel slip) based interface has many benefits, there are strict safety requirements that vehicles on public roads must meet with respect to preventing excessive wheel slip and loss of vehicle stability. A great deal of testing, validation and documentation must be performed before a VMM based wheel speed or wheel slip interface can be delivered to public roads.

[0040] It is therefore desirable to reduce the safety requirements on the VMM and MSD speed control loops by adding a "safety net" function that prevents these functions from locking the wheels and / or introducing unwanted yaw motion. The existing anti-lock braking, traction control and stability control functions that exist in today's brake systems can be used to provide this safety net with some small modifications to the existing communication signals and special considerations in the VMM with respect to the distribution of speed requests.

[0041] The VMM is of course designed such that the vehicle motion remains within the operational design domain of the vehicle, i.e. such that the wheel slip remains within acceptable bounds and optionally also such that the vehicle yaw rate does not exceed a set safety level. However, for various reasons the VMM function can potentially generate control commands that inadvertently lead to undesirable wheel behavior. If this happens, safety measures must be taken to mitigate the consequences of this unexpected wheel behavior.

[0042] The present disclosure relates to a technology in which a capability range is defined that includes a range of acceptable wheel behavior, e.g. in terms of wheel slip and / or wheel rotational acceleration. As long as the wheel behavior remains within the bounds set by this capability range, the VMM is allowed to control the different MSDs. However, if the wheel behavior goes beyond this capability range, the MSD control unit triggers one or more control intervention functions.

[0043] For excessive positive wheel slip - when a wheel slip exceeding a given threshold and / or a large positive wheel rotational acceleration is measured - the MSD control unit can impose a torque limit on the propulsion device in an attempt to let the wheel return to the stable part of the tire curve (see below for a more detailed discussion of the tire curve). Figure 3 For excessive positive wheel slip - when a wheel slip exceeding a given threshold and / or a large positive wheel rotational acceleration is measured - the MSD control unit can impose a torque limit on the propulsion device in an attempt to let the wheel return to the stable part of the tire curve (see below for a more detailed discussion of the tire curve).

[0044] If the slip only occurs on one side of the driven axle, this typically indicates a split-mu situation: where the available friction on one side of the road is higher than on the other side. In this case, the brake system can in addition to imposing a torque limit also provide a brake torque on the spinning wheel in order to transfer drive torque to the non-slippery wheel through an open differential.

[0045] For excessive negative slip (e.g. during engine braking, or due to driveline inertia) - when wheel slip exceeding a given threshold and / or large negative wheel rotational acceleration is measured, the MSD control unit can impose a "zero engine braking" torque limit on the propulsion unit. This limit can either be communicated as a torque limit signal by the MSD control unit from the braking system to the propulsion unit, or it can be communicated by the MSD control unit simply sending an "anti-lock braking activated" signal, in which case the propulsion unit is required to release all braking torque.

[0046] In case the wheels are approaching a wheel lock-up situation due to e.g. downshifting, the MSD control unit can in some situations request positive torque from the propulsion unit in order to bring the wheel slip back into the stable region of the tire curve.

[0047] The above described approach to handling critical wheel behavior by the MSD controller (e.g. an electronic brake system (EBS)) has "proven in use" and represents a reasonable choice when the propulsion means is very slow to respond (i.e. has a low control bandwidth). The above described approach also puts relatively simple safety requirements on the propulsion means (e.g. it should always release braking torque when the anti-lock braking signal becomes active), which is an advantage.

[0048] The relevant capability range can e.g. be determined by computer simulation or by actual experiments. In some cases, the capability range can also be inherited from traditional safety systems, such as anti-lock systems and systems for traction control. This can e.g. be done by determining when the traditional safety system intervenes, and then defining the capability range based on this operating point, possibly with some additional safety margin. This will be further discussed below in connection with Figure 3 The capability range relating to wheel slip is discussed in more detail.

[0049] Figure 2 A wheel end portion of a vehicle 100 in which the proposed technology can be implemented is shown. A wheel 210 is associated with a wheel behavior (e.g. current wheel slip and / or wheel acceleration). A service brake 220 is arranged to generate negative torque to brake the wheel 210. The service brake can e.g. be a friction brake, a drum brake or any other type of brake configured to generate negative torque, as schematically illustrated in Figure 2 Fig. 1. The service brake can e.g. be a friction brake, a drum brake or any other type of brake configured to generate negative torque, as schematically illustrated in

[0050] The MSD control unit 230 is communicatively coupled to the VMM 260 via the interface 235, and is configured to control the service brakes 220 via the service brake interface 225. The control is facilitated by wheel behavior data received from the wheel speed sensor (WS) 240, e.g. the current wheel speed. The wheel speed data can be received directly from the wheel speed sensor 240 via the interface 245, or indirectly via the VMM 260 through the interface 235.

[0051] Vehicle state information from one or more vehicle state sensors 270 is available via the vehicle state interface 275. The vehicle state information can for example include an accurate estimate of the vehicle speed, which if converted into the coordinate system of the wheel 210, can be used to accurately determine wheel slip, which will be discussed in more detail below.

[0052] According to the example in Figure 2 The VMM 260 is also arranged to control the propulsion device 250, according to the example in

[0053] According to SAE J670 (SAE Vehicle Dynamics Standards Committee, January 24, 2008), the longitudinal wheel slip λ can be defined as:

[0054]

[0055] where R is the effective wheel radius in meters, ω x is the angular velocity of the wheel, v x is the longitudinal velocity of the wheel (in the coordinate system of the wheel). Thus, λ is between -1 and 1, and quantifies the degree of wheel slip relative to the road surface. Wheel slip is essentially the speed difference measured between the wheel and the vehicle. Thus, the techniques disclosed herein can be applicable to any type of wheel slip definition.

[0056] The VMM 260 (and optionally also the MSD control unit 230) maintains information about v x (in the reference coordinate system of the wheel), while the wheel speed sensor 240 etc. can be used to determine ω.

[0057] It is noted that in the following, when discussing limits of wheel slip, the limit is the magnitude or absolute value of the wheel slip. That is, an increased wheel slip limit can refer to a larger positive allowable wheel slip or a smaller negative allowable wheel slip.

[0058] Figure 3is a graph showing the achievable tire force as a function of wheel slip. The achievable longitudinal tire force Fx presents a nearly linear increasing part 310 for small wheel slips, followed by a part 320 with more nonlinear behavior for large wheel slips. The achievable lateral tire force Fy decreases rapidly even at relatively small longitudinal wheel slips. It is desirable to maintain vehicle operation in the linear region 310 where the achievable longitudinal force in response to an applied brake command is more easily predictable and sufficient lateral tire force can be generated if needed. To ensure operation in this region, a wheel slip limit λ of e.g. approximately 0.1 can be imposed on a given wheel LIM .

[0059] This type of tire model can be used by the VMM to generate a desired tire force on a certain wheel. Instead of requesting a torque corresponding to the desired tire force, the VMM can convert the desired tire force to an equivalent wheel slip and request this slip. The main advantage is that the MSD control will be able to maintain operation at the desired wheel slip with higher bandwidth to deliver the requested torque. x and the wheel rotation rate ω x to deliver the requested torque.

[0060] For example, an effective capability range can be determined from the tire force curves. As long as the wheel slip is kept below 0.1 (i.e. in the range between 0-0.1), force coordination and overall vehicle motion management is relatively simple. However, once the wheel slip goes beyond this range, control becomes much more difficult.

[0061] Figure 4 An example capability range 400 is schematically shown. This particular example of a capability range has three dimensions 401, 402, 403. One dimension can correspond to wheel slip, another dimension can correspond to wheel acceleration, and a third dimension can correspond to vehicle yaw rate. According to the present teachings, as long as the wheel behavior is kept within a defined capability range 410, the VMM is allowed to control the MSD by sending control commands to the MSD control unit 230 via the interface 235, 255 and to the propulsion means 250. However, if an event occurs that makes the current wheel behavior go beyond the defined capability range 410, the MSD control unit 230 triggers a control intervention function. This control intervention function can comprise the MSD function overriding the control commands received from the VMM, or it can comprise the MSD control unit requesting vehicle control by sending a request to some external arbitrator function that then decides whether the request for overriding control should be granted or not.

[0062] Reference is made to Figure 2The MSD control unit 230 is configured to control one or more MSDs 220, 250 associated with the wheel 210. The one or more MSDs can comprise at least one service brake 220 arranged to generate negative torque by the wheel 210, and a propulsion unit 250 arranged to generate positive and / or negative torque by the wheel 210, e.g. an electric machine and / or an internal combustion engine. The MSD control unit 230 is communicatively coupled 235 to the VMM unit 260 for receiving control commands including wheel speed requests and / or wheel slip requests from the VMM unit 260 for controlling vehicle motion by the one or more MSDs 220, 250.

[0063] It should be appreciated that the MSD control unit discussed herein can also be configured to control one or more MSDs associated with other wheels than the wheel 210, e.g. for controlling the wheels of a given axle, or the wheels located on one side of a trailer unit, or all wheels of a trailer unit.

[0064] The MSD control unit 230 is arranged to obtain a capability range indicative of a wheel behavior range of the wheel 210 for which the VMM unit 260 is allowed to influence the behavior of the wheel by said control commands. The capability range is indicative of operating states of the vehicle and the wheel that are considered to be safe. According to various aspects, the capability range can comprise any of the following: an upper limit of allowed positive and / or negative longitudinal wheel slip, an upper limit of allowed positive and / or negative longitudinal wheel acceleration, and / or an upper limit of allowed positive and / or negative vehicle yaw rate. The capability range can be a fixed capability range obtained as parameters loaded from memory or received from an external configuration entity, or a dynamic capability range continuously updated according to e.g. driving scenario and vehicle state, such as vehicle load, estimated road friction, and other scenario parameters.

[0065] The allowed slip, acceleration, and yaw rate ranges can of course also have lower limits. Typically, the upper limit is positive and the lower limit is negative. However, there can also be scenarios and use cases where both the upper and lower limits are negative or both the upper and lower limits are positive.

[0066] The MSD control unit 230 is also arranged to monitor the wheel behavior, e.g. by the wheel sensor 240, and to detect whether the wheel behavior is outside said capability range. Such monitoring can comprise filtering samples of wheel behavior over time, in which case the detection can be based on the result of the filtering.

[0067] If the monitored wheel behaviour is outside the capability range, the MSD control unit 230 triggers a control intervention function. This control intervention function can for example comprise an intervention function performed by one or more of the MSDs 220, 250, as described above. The control intervention function can also comprise triggering a request to an external arbitrator function (which can be comprised in the VMM or some other VUC module) for direct MSD control by the MSD control unit 230.

[0068] The VMM unit 260 is communicatively coupled 235 to the MSD control unit 230 and sends control commands comprising wheel speed requests and / or wheel slip requests to the MSD control unit 230 for controlling the vehicle motion by one or more of the MSDs 220, 250.

[0069] The VMM unit 260 is arranged to obtain an above-mentioned capability range, which indicates a range of wheel behaviour of the wheel 210 for which the VMM unit 260 is allowed to influence the wheel’s behaviour by said control commands. The VMM unit 260 is further arranged to generate said control commands such that the wheel behaviour is within said capability range.

[0070] According to some aspects, the VMM unit 260 comprises an arbitrator function configured to receive a request for direct MSD control by the MSD control unit 230 and to yield vehicle control to the MSD control unit 230 in case the wheel behaviour is outside a predetermined safe range of wheel behaviour. The arbitrator function can be arranged to take other factors into account when deciding whether the VMM should be allowed to control the wheel behaviour or whether the MSD control unit should be allowed to intervene and take over by performing e.g. an anti-lock function or a traction control function. The VMM unit can also be arranged to generate a request to the arbitrator function in order to temporarily control a certain wheel or wheels outside the current capability range. This can for example occur if an emergency manoeuvre is to be performed. In this case, the arbitrator function can allow the VMM to control one or more wheels to have a wheel behaviour outside said capability range for a limited period of time.

[0071] Figure 5 A truck or tractor vehicle 110 with a VMM 260 is schematically illustrated, which is arranged to control a plurality of MSD control units 230a, 230b, 230c, 230d, 230e, 230f. Each MSD control unit is arranged to control a respective wheel 210a, 210b, 210c, 210d, 210e, 210f.

[0072] Figure 6A truck or tractor vehicle 110 connected to a trailer vehicle 120 is schematically illustrated. A first VMM unit 260a sends control commands to the MSD control unit on the truck 110, while a second VMM unit 260b operates in slave mode with respect to the first VMM unit 260a, sending control commands to the MSD control units associated with the wheels on the trailer unit 120. The communication link 610 between the different VMM units 260a, 260b is preferably a wired connection, but wireless connections are also considered.

[0073] Figure 7 is a flowchart illustrating a method summarizing at least some of the above discussion. Therein is illustrated a method for controlling the motion of a heavy vehicle 100. The method comprises configuring S1 the MSD control unit 230 to control one or more MSDs 220, 250 associated with wheels 210 on the vehicle 100, as exemplified above in connection with Figure 2 The method further comprises configuring S2 the VMM unit 260 to perform vehicle motion management by the one or more MSDs 220, 250 via control commands sent to the MSD control unit 230, and defining S3 a capability range indicative of a wheel behavior range of the wheels 210 for which the VMM unit 260 is allowed to influence the behavior of the wheels by the control commands. The method further comprises monitoring S4 the wheel behavior, and in case the monitored wheel behavior exceeds the defined capability range, triggering S5 a control intervention function by the MSD control unit 230, as discussed above.

[0074] Figure 8 Components of a control unit 800 according to embodiments discussed herein, such as the VUC 130, 140, the MSD control unit 230 or the VMM unit 260, are schematically illustrated in the form of a number of functional units. The control unit 800 is configured to perform at least some of the functions discussed above for controlling a heavy vehicle 100. Processing circuitry 810, which can comprise any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., is arranged to execute software instructions stored in a computer program product, e.g. in the form of a storage medium 820. The processing circuitry 810 can further be provided as at least one application-specific integrated circuit (ASIC), or field

[0075] In particular, the processing circuitry 810 is configured to cause the control unit 101 to perform a set of operations or steps, e.g. in connection with Figure 7The method discussed can for instance be implemented by the control unit 800 in that the set of operations is performed. The control unit 800 can thus be implemented to execute methods as disclosed herein. This is for instance the case when the control unit 800 is implemented as a processor and / or as an application specific integrated circuit. The set of operations can be provided as a set of executable instructions. Therefore, the control unit 800 is thereby arranged to execute methods as disclosed herein.

[0076] The storage medium 820 can also include a permanent storage, which, for example, can be any single one or combination of magnetic storage, optical storage, solid state storage or even remotely mounted storage.

[0077] The control unit 800 can further include an interface 830 for communication with at least one external device. The interface 830 can for instance include one or more transmitters and receivers that include analog and digital components and suitable number of ports for wired or wireless communication.

[0078] The processing circuitry 810 controls the general operation of the control unit 800, e.g. by sending data and control signals to the interface 830 and the storage medium 820, by receiving data from the interface 830 and reporting to the outside, and by retrieving data and instructions from the storage medium 820. Other components and functionalities of the control node are omitted in order not to obscure the concepts presented herein.

[0079] Figure 9 A computer readable medium 910 is shown, carrying a computer program comprising program code means 920 for performing the methods as shown in Figure 7 when said program product is run on a computer. The computer readable medium and code means can together form a computer program product 900.

Claims

1. A motion support device, MSD, control unit (230) for a heavy-duty vehicle (100), the control unit (230) being configured to control one or more MSDs (220, 250) associated with at least one wheel (210) on the vehicle (100), wherein the MSD control unit (230) being arranged to be communicatively coupled (235) to a vehicle motion management, VMM, unit (260) for receiving control commands comprising wheel speed requests and / or wheel slip requests from the VMM unit (260) for controlling vehicle motion by the one or more MSDs (220, 250), wherein the MSD control unit (230) is arranged to obtain a capability range indicative of a wheel behavior range of the wheel (210) for which the VMM unit (260) is allowed to influence behavior of the wheel by the control commands, and wherein the MSD control unit (230) is arranged to monitor wheel behavior and detect whether the wheel behavior is outside the capability range, wherein the MSD control unit (230) is arranged to trigger a control intervention function if the monitored wheel behavior is outside the capability range, wherein the control intervention function is arranged to prevent the VMM unit (260) from influencing behavior of the wheel by the control commands if the wheel behavior is outside the capability range.

2. The MSD control unit (230) according to claim 1, wherein the one or more MSDs comprise at least one service brake (220) arranged to generate negative torque by the wheel (210).

3. The MSD control unit (230) according to claim 1 or 2, wherein the one or more MSDs comprise at least one propulsion unit (250) arranged to generate positive and / or negative torque by the wheel (210).

4. The MSD control unit (230) according to claim 1 or 2, wherein the capability range comprises an upper limit for allowed positive and / or negative longitudinal wheel slip and / or wheel rotational speed.

5. The MSD control unit (230) according to claim 1 or 2, wherein, the capability range comprises an upper limit for allowed positive and / or negative longitudinal wheel acceleration.

6. The MSD control unit (230) according to claim 1 or 2, wherein the capability range comprises an upper limit for allowed positive and / or negative vehicle yaw rate.

7. The MSD control unit (230) according to claim 1 or 2, wherein the capability range comprises a lower limit for allowed positive and / or negative longitudinal wheel slip and / or wheel rotational speed.

8. The MSD control unit (230) according to claim 1 or 2, wherein the capability range comprises a lower limit for allowed positive and / or negative longitudinal wheel acceleration.

9. The MSD control unit (230) according to claim 1 or 2, wherein, the capability range comprises a lower limit for allowed positive and / or negative vehicle yaw rate.

10. The MSD control unit (230) according to claim 1 or 2, the MSD control unit (230) being arranged to receive wheel speed data associated with the wheel (210) from a wheel speed sensor (240) and to detect whether the wheel behavior is outside the capability range based on the wheel speed data.

11. The MSD control unit (230) according to claim 1 or 2, arranged to obtain a fixed capability range as a parameter received from memory or from an external configuration entity.

12. The MSD control unit (230) according to claim 1 or 2, arranged to continuously obtain an updated capability range.

13. The MSD control unit (230) according to claim 1 or 2, wherein, The control intervention function comprises an intervention function performed by one or more of the MSDs (220, 250).

14. The MSD control unit (230) according to claim 1 or 2, wherein, The control intervention function comprises triggering a request to an external arbitrator function for direct MSD control by the MSD control unit (230).

15. The MSD control unit (230) according to claim 1 or 2, wherein, The MSD control unit (230) is arranged to monitor wheel behaviour by filtering samples of wheel behaviour over time, and to detect whether the wheel behaviour is outside the capability range based on the result of the filtering.

16. A vehicle motion management, VMM, unit (260) arranged to perform vehicle motion management to control motion of a heavy vehicle (100) by one or more motion support devices, MSDs, (220, 250) associated with at least one wheel (210) on the vehicle (100), wherein, The VMM unit (260) is arranged to be communicatively coupled (235) to a MSD control unit (230) for sending control commands comprising wheel speed requests and / or wheel slip requests to the MSD control unit (230) for controlling vehicle motion by the one or more MSDs (220, 250), wherein the VMM unit (260) is arranged to obtain a capability range indicative of a wheel behaviour range of the wheel (210) for which the VMM unit (260) is allowed to influence the behaviour of the wheel by the control commands, wherein the VMM unit (260) is arranged to generate the control commands such that the wheel behaviour is within the capability range, and wherein the VMM unit (260) comprises an arbitrator function configured to receive a request for direct MSD control by the MSD control unit (230), and to yield vehicle control to the MSD control unit (230) if the wheel behaviour is outside a predetermined wheel behaviour safety range.

17. A vehicle (100) comprising a motion support device, MSD, control unit (230) according to any of claims 1-15, and a vehicle motion management, VMM, unit (260) according to claim 16.

18. A method for controlling motion of a heavy vehicle (100), the method comprising: configuring (S1) a motion support device, MSD, control unit (230) to control one or more MSDs (220, 250) associated with at least one wheel (210) on the vehicle (100), configuring (S2) a vehicle motion management, VMM, unit (260) to perform vehicle motion management by the one or more MSDs (220, 250) via control commands sent to the MSD control unit (230), defining (S3) a capability range indicative of a wheel behavior range of the wheel (210) for which the VMM unit (260) is allowed to influence the behavior of the wheel by the control commands, monitoring (S4) wheel behavior, and in case the monitored wheel behavior is outside the defined capability range, triggering (S5) a control intervention function by the MSD control unit (230), wherein the control intervention function is arranged to prevent the VMM unit (260) from influencing the behavior of the wheel by the control commands if the wheel behavior is outside the capability range.

19. A computer readable medium (910) carrying a computer program (920), the computer program (920) comprising program code means for performing the steps of the method of claim 18 when the computer program is run on a computer or on the processing circuit (810) of the control unit (800).

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