A robust actuator control method for dynamics management of large vehicles.

Abstract

A control unit (230) for controlling at least one torque generating motion assist device (torque generating MSD) (220, 250) on a large vehicle (100), the control unit (230) controlling a desired positive longitudinal tire force (F) generated by the torque generating MSD (220, 250). x ) to indicate the motor demand (T i ) that indicates the current torque generated by the torque generating MSD (220, 250) and EST ) and obtain the motion request (T i ) and the estimated applied torque (T EST ) based on the target wheel speed (ω i ) and determine the target wheel speed (ω i ) and the control unit (230) is configured to set the torque generating MSDs (220, 250) to maintain the set wheel speed (ω i ) increases with the estimated applied torque (T EST ) to cause a decrease in the target wheel speed (ω i ) is configured to reduce

Description

[Technical field]

[0001] This disclosure relates to vehicle dynamics management for electric heavy vehicles, i.e., coordinated control of electric machines and other dynamics aids, such as service brakes and steering.

[0002] The present invention may be advantageously applied to large vehicles such as trucks, buses, and construction machinery. [Background technology]

[0003] Vehicles are becoming increasingly complex in terms of mechanics, aerodynamics, hydraulics, electronics, and software. Modern heavy vehicles may include a wide range of different torque-generating physical devices, such as a combustion engine, one or more electric machines, friction brakes, and electromagnetic brakes. These physical devices are commonly known as torque-generating motion support devices (MSDs) and may be controlled by respective MSD control units that are often located in direct connection with the MSD actuators. The local MSD control units are typically connected to a central vehicle controller, which is configured to execute the entire vehicle motion management VMM by coordinating the different MSDs to obtain the desired motion by the vehicle.

[0004] The interface between the central VMM controller and the torque generating MSDs is traditionally based on torque requests determined by the central VMM control unit and transmitted to the local MSD control units via a torque-based interface. However, the interface between the central controller and the local controllers typically has limited bandwidth and may involve significant latency, hindering the efficiency of vehicle dynamics management in responding to sudden and unexpected changes in operating conditions.

[0005] Significant improvements in responsiveness may be achieved by instead using wheel speed or wheel slip based requirements in the interface between the central controller and the local controllers, as discussed in WO2021144010A1. This type of control may overcome the interface bandwidth problem, but relies on the relationship between tire forces and wheel slip generated at the wheels of a large vehicle being at least approximately known, which may not always be the case, for example, when road conditions are unknown or when one or more important vehicle characteristics, such as load weight, are unknown. Summary of the Invention

[0006] It is an object of the present disclosure to provide a wheel slip based control method that can function even when little is known about the current relationship between wheel slip and tire forces. It is a further object of the present disclosure to provide a wheel slip based control method that does not require precise data regarding ground vehicle speed.

[0007] This object is achieved at least in part by a control unit for controlling at least one torque generating MSD on a heavy vehicle, the control unit being adapted to control a desired positive longitudinal tire force F generated by the torque generating MSD. x A motion demand T i and receiving an estimated applied torque T indicative of a current positive torque generated by at least one torque generating MSD. EST Further, the control unit is configured to obtain a motion request T i and the estimated applied torque T EST Based on the target wheel speed ω i In addition to determining the target wheel speed ω i and the control unit is configured to set the torque generation MSD to maintain the set wheel speed ω i The increase in the estimated applied torque T EST If this results in a decrease in the target wheel speed ω i The device is configured to perform a backoff procedure including reducing

[0008] In this way the control unit can detect when the peak tire force has passed and when the tire has entered a region of the inverse tire model where a further increase in wheel speed will result in a reduction in wheel force. This operation does not require explicit knowledge of any inverse tire model or precise information about the ground vehicle speed. The technique proposed herein can be applied by itself or as a back-up method to an inverse tire model based control method for heavy vehicle motion management.

[0009] The techniques disclosed herein are also applicable in braking situations, i.e. when negative torque is required to slow a large vehicle.

[0010] According to an aspect, the at least one MSD includes an electric machine, and the estimated applied torque is based at least in part on a motor current associated with the electric machine. This type of torque estimation is particularly fast because it is based on electrical measurements rather than mechanical sensors. However, it will be appreciated that the estimated applied torque may also be based at least in part on an output from a torque sensor, such as a strain force sensor. According to a preferred embodiment, the at least one MSD comprises a wheel hub electric machine including an integrated electronic control unit (ECU) configured to output a signal having the estimated applied torque.

[0011] The control unit is optionally configured to determine a relationship between the target wheel speed and the torque generated by the torque generating MSD based on the sequence of the estimated applied torque and the correspondingly configured wheel speed. This relationship can be output to a central controller or some other entity that can use the information in optimizing vehicle control. For example, the control unit can be configured to output data indicative of the determined model as a capability signal to a higher layer control function in a layered heavy vehicle control architecture.

[0012] According to some further aspects, the estimated applied torque is compensated by the control unit for one or more predetermined wheel and / or driveline characteristics, such as predetermined or estimated inertia and / or stiffness values, thereby providing a more accurate estimate of the applied torque, especially during dynamic transient behavior. Additionally, the estimated applied torque may be determined based at least in part on predetermined electric machine windup characteristics, thereby further improving the estimated torque.

[0013] According to another aspect, the control unit is configured to vary the target wheel speed around a nominal target wheel speed value and monitor the estimated applied torque as a function of the variation of the target wheel speed, which enables the control unit to examine the fundamental relationship between wheel force and wheel slip (or wheel speed) in order to gain knowledge about the location of the peak of the wheel force curve.

[0014] Furthermore, the control unit may be configured to set the current torque generating capacity as the estimated applied torque if an increase in the set wheel speed results in a decrease in the estimated applied torque, which may be used by higher layer control functions, for example in controlling large vehicles more accurately.

[0015] According to some additional aspects, the control unit is configured to increase the set control bandwidth of the MSD actuator when an increase in the set wheel speed results in a decrease in the estimated applied torque. Increasing the set control bandwidth improves the responsiveness of the MSD, which is an advantage when the tire operating point is transitioning from its linear region to its nonlinear region.

[0016] Also disclosed herein are computer programs, computer readable media, computer program products, and vehicles associated with the above advantages.

[0017] Generally, all terms used in the claims should be interpreted according to their ordinary meaning in the art, unless otherwise specified herein. All references to "elements, devices, components, means, steps, etc." should be openly interpreted as referring to at least one example of the elements, devices, components, means, steps, etc., unless otherwise specified. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless otherwise specified. Further features of the present invention and advantages associated with the present invention will become apparent upon review of the appended claims and the following description. Those skilled in the art will understand that different features of the present invention can be combined to create embodiments other than those described below without departing from the scope of the present invention.

[0018] Below follows a more detailed description of embodiments of the invention, cited as examples, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing an example of a large vehicle. [Diagram 2] FIG. 2 is a diagram illustrating a control arrangement of the exercise support device. [Diagram 3] FIG. 1 is a diagram illustrating a layered vehicle control function architecture. [Figure 4] FIG. 2 is a schematic diagram of an exemplary inverse tire model. [Diagram 5] FIG. 2 is a schematic diagram of an exemplary inverse tire model. [Figure 6] FIG. 2 is a schematic diagram of an exemplary inverse tire model. [Figure 7] 4 is a graph illustrating an example wheel speed control strategy. [Figure 8] 1 is a flow chart illustrating a method. [Figure 9] FIG. 2 is a schematic diagram of a control unit. [Figure 10]FIG. 1 illustrates an exemplary computer program product. [Figure 11] FIG. 1 illustrates an example of a fitted model based on measurements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which show certain aspects of the invention. However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments and aspects set forth herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0021] It should be understood that the invention is not limited to the embodiments described herein and shown in the drawings, but rather, those skilled in the art will recognize that many variations and modifications may be made within the scope of the appended claims.

[0022] FIG. 1 illustrates an exemplary vehicle 100 for transporting cargo to which the technology disclosed herein may be advantageously applied. The vehicle 100 includes a tractor or towing vehicle 110 supported on front wheels 150 and rear wheels 160, at least some of which are driven wheels. Typically, but not necessarily, all of the tractor wheels are braked wheels. The tractor 110 is configured to tow a first trailer unit 120 supported on trailer wheels 170 by a fifth wheel connection in a known manner. The trailer wheels are typically braked wheels, but one or more axles may also include driven wheels.

[0023] It will be appreciated that the methods and control units disclosed herein may also be advantageously applied in other types of heavy vehicles such as rigid trucks, trucks with drawbar connections, construction equipment, buses, etc.

[0024] The tractor 110 includes a vehicle unit computer (VUC) 130 for controlling various kinds of functions, i.e. propulsion, braking, and steering. Some trailer units 120 also include a VUC 140 for controlling various functions of the trailer, such as braking of the trailer wheels, and often propulsion of the trailer wheels. The VUCs 130, 140 may be centralized or distributed over several processing circuits. Also, some of the vehicle control functions may be executed remotely, for example on a remote server 190 connected to the vehicle 100 via a wireless link 180 and a wireless access network 185.

[0025] One or more sensor devices 115, 116 mounted on the vehicle 100 are configured to provide input data to the VUC. These sensor devices may be used for vehicle environment estimation, i.e. to obtain information about the surrounding environment in which the vehicle 100 is operating. Using one or more sensor devices, the speed of the vehicle and / or one of the wheels relative to the road surface, v x The information from the sensors 115, 116 may also include data regarding the geometry of the road ahead of the vehicle, the nature of the road surface, the temperature, wind conditions, etc.

[0026] The VUC 130 of the tractor 110, and possibly also the VUC 140 of the trailer 120, may be configured to execute vehicle control methods that are organized according to a layered functional architecture in which some functions may be included in a traffic situation management (TSM) domain at a higher layer and some other functions may be included in a vehicle motion management (VMM) domain that resides in a lower functional layer.

[0027] 2 shows a schematic of a function 200 for controlling wheels 210 by some exemplary MSDs, here including friction brakes 220 (such as disc or drum brakes), a means of steering 290 such as a power steering arrangement, and a propulsion device 250. One or more propulsion devices may be used to power the vehicle 100. For example, a central propulsion device may be connected to the wheels of the drive axle by a differential. Separate electric machines may also be connected to some of the wheels of the vehicle. These separate electric machines allow greater freedom of control of the actuators, as they can be controlled independently of each other.

[0028] The friction brakes 220 and propulsion devices are examples of wheel torque generating devices, sometimes called actuators, that may be controlled by one or more motion support device control units 230. The control is based on measurement data obtained, for example, from wheel speed sensors 240 and other vehicle condition sensors, such as radar sensors, lidar sensors, and vision-based sensors, such as camera sensors and infrared detectors. Part of the control is optionally based on ground vehicle speed 280. However, an advantage of the techniques disclosed herein is that this information is not strictly necessary.

[0029] Other examples of torque generating motion assist devices that may be controlled according to the principles described herein include engine retarders and power steering devices. The MSD control unit 230 may be arranged to control one or more actuators. For example, it is not uncommon for the MSD control unit 230 to be arranged to control both wheels on an axle.

[0030] The TSM function 270 plans driving maneuvers over a time horizon, such as 10 seconds. This period corresponds, for example, to the time it takes the vehicle 100 to negotiate a curve. Vehicle steering planned and executed by the TSM can be associated with acceleration and curvature profiles that represent the desired vehicle speed and turning for a given maneuver. The TSM receives the desired acceleration profile a from the VMM function 260 and distributes forces to satisfy requests from the TSM in a safe and robust manner. req and curvature profile c req The VMM function 260 continuously requests (275) capability information to the TSM function 270 detailing the current capabilities of the vehicle in terms of, for example, forces, maximum speed, and acceleration that can be generated.

[0031] Of course, the acceleration and curvature profiles may be obtained from the driver of the large vehicle via conventional control input devices such as a steering wheel, accelerator pedal, and brake pedal, etc. The sources of said acceleration and curvature profiles are not within the scope of this disclosure and will not be described in greater detail herein.

[0032] The wheel 210 has a longitudinal velocity component v x and the lateral velocity component v y The longitudinal tire force F x and lateral tire force F y Unless otherwise stated, tire forces are defined in the wheel's coordinate system, i.e. longitudinal forces are directed in the plane of rotation of the wheel and lateral tire forces are directed perpendicular to the plane of rotation of the wheel. The rotational speed of the wheel is ω x , the radius is R.

[0033] Referring also to FIG. 3, the VMM function 260 operates with a planned period of about 1 second and an acceleration profile a req and curvature profile c reqinto control commands for controlling vehicle motion functions actuated by various MSDs 220, 250, 290 of the vehicle 100, and the MSDs report capabilities 231, 232, 233 to the VMM function 260, which are then used as constraints for vehicle control.

[0034] The reported capabilities may include, for example, the estimated current torque applied to one or more wheels, the estimated maximum torque (positive and / or negative) that can be generated under the current operating conditions, the maximum longitudinal tire force (F x ), maximum possible lateral force (F y ), etc. The reported capabilities may also include status signals, such as warning and error messages indicating malfunctions.

[0035] The VMM function 260 performs vehicle state or motion estimation 305, i.e., the VMM function 260 continuously determines the current vehicle state s(t) at time t, including the positions, speeds, accelerations, and articulation angles of the various units of the vehicle combination, by monitoring operation using various sensors 306 located on the vehicle 100 that are often, but not necessarily, connected to the MSDs 220, 250, 290.

[0036] The VMM function 260 also optionally performs motion estimation 310, i.e., estimating the future vehicle state s(t+T) at one or more time points t+T in the future. Both motion estimation 305 and motion estimation 310 are commonly known techniques and several exemplary implementations exist in the literature. Therefore, these sub-functions are not described in further detail herein.

[0037] The results of the motion estimation 305 and optional motion prediction 310, i.e. the estimated vehicle state s(t) and the predicted future vehicle state s(t+T), are input to a force generation module 320, which determines the total forces V=[V1, V2] required for the different vehicle units and generates the required acceleration profile a req and curvature profile c req The vehicle 100 is moved in accordance with the above.

[0038] The total required force vector V is input to an MSD coordination function 330, which allocates tire forces and coordinates other MSDs such as steering and suspension. Together, the coordinated MSDs then provide the desired lateral and longitudinal forces Fy and Fx, as well as the required moments Mz, on the vehicle units to obtain the desired motion through the vehicle linkage 100.

[0039] The output of the MSD coordination function 330 is the classical torque demand T i and steering angle requirement δ i The request may include: a request for a vehicle actuator that is connected to the central controller and one or more local MSD controllers; the request is sent via an interface 265 between the central controller and one or more local MSD controllers. This interface may be based on a controller area network (CAN) bus, or some other network technology, such as an Ethernet link. A problem in many large vehicle architectures is that the interface between the central controller and the local MSD controllers has limited bandwidth, which may result in significant delays in requests sent over the interface. This means that the response time of the vehicle actuators to a change in operating conditions, such as a sudden decrease in road friction, may not be fast enough to successfully compensate for the change in operating conditions.

[0040] Longitudinal wheel slip λ x can be defined as follows in accordance with SAE J670 SAE Vehicle Dynamics Standards Committee January 24, 2008:

number

[0041] For a wheel or tire to generate tire force, slip must occur. For small slip values, the relationship between slip and the force generated is approximately linear, and the proportionality constant is often expressed as the tire's slip stiffness. The normal force F acting on the tire of the wheel 210 is z is key to determining several important vehicle characteristics. For example, normal force is the lateral tire force F that can be achieved by the wheel. y To a large extent, this is because, usually, F x ≦μF z where μ is the friction coefficient associated with the current road friction conditions. The maximum available lateral force for a given lateral slip can be expressed by the so-called magic formula, as described in "Tyre and vehicle dynamics" by Hans Pacejka, Elsevier Ltd. 2012, ISBN 978-0-08-097016-5.

[0042] In this document, an inverse tire model is a model of wheel behavior that describes tire forces generated in the longitudinal direction (rolling direction) and / or lateral direction (orthogonal to the longitudinal direction) as a function of wheel slip. In "Tyre and vehicle dynamics", Elsevier Ltd. 2012, ISBN 978-0-08-097016-5, Hans Pacejka covers the fundamentals of tire models. See for example chapter 7 where the relationship between wheel slip and longitudinal forces is explained.

[0043] 4 is a graph showing an example of achievable tire forces as a function of wheel slip λ, i.e., an example of an inverse tire model, it should be noted that the tire force values ​​on the axles are merely example values ​​and should not be construed as limiting the present disclosure. x shows a portion 410 that increases approximately linearly for small wheel slips, followed by a portion 420 with a more non-linear behavior for larger wheel slips. Note that there is a peak 430 beyond which tire forces decrease with wheel slip, i.e., if the wheel speed increases above a given wheel speed, the generated tire force decreases. The resulting lateral tire force F y decreases rapidly even with relatively small longitudinal wheel slips. It is desirable to keep the vehicle operating in the linear region 410, where the longitudinal forces obtainable in response to the applied brake command are easy to predict and sufficient lateral tire forces can be generated when required. Where wheel slip is larger, e.g., above 0.1, a more nonlinear region 420 is found. Control of the vehicle in this region can be difficult and is therefore often avoided. It may be interesting for traction, such as in off-road conditions, but not for on-road operation, although a larger slip limit for traction control may be preferable. To ensure operation in this region, a wheel slip limit λ, e.g., on the order of 0.1, may be used. LIM can be imposed on a given wheel. However, this requires that the ground vehicle speed is known with sufficient reliability and accuracy, and furthermore, setting the wheel slip limit requires some basic information about the inverse tire model given the current operating conditions of the wheel 210, i.e., the road friction conditions, the normal load, and the characteristics of the interaction between the tire tread and the road surface.

[0044] Classic torque control loops for large vehicles, as mentioned above, are typically associated with time constants on the order of 10 ms or so, which may not be fast enough to react to changes in, for example, road friction. To improve vehicle dynamics management, the VMM 260 can use an inverse tire model to instead generate a desired tire force at a wheel. Then, instead of requesting a torque corresponding to the desired tire force, the VMM can convert the desired tire force to an equivalent wheel slip (or, equivalently, wheel speed relative to ground speed) and request this slip instead. The main advantage is that the MSD control device 230 can calculate the torque based on the vehicle speed v x and the wheel rotation speed ω x The advantage of this approach is that it is possible to provide the requested torque at a much higher bandwidth by using a tread pattern to maintain operation at the desired wheel slip, since the control loop is now local on the MSD side of the interface 265, avoiding the delay 340 at the interface between the central VMM controller and the local MSD controller. These concepts are explained in WO2021144010A1. Of course, this approach assumes that the inverse tire model is at least approximately known, and furthermore that the vehicle speed v x and the wheel rotation speed ω x This requires that reasonably accurate data regarding the number of VMMs is available to the central VMM control unit 260. As noted in the introduction to this disclosure, this may not always be the case.

[0045] Referring to example 500 of FIG. 5, where the inverse tire model is F xAssume that the vehicle 100 is accelerating (wheel force request is positive). A tire force of about 6 kN is initially set (520), corresponding to a wheel slip of about 0.05. Further acceleration is then desired and the tire force is increased (530) to about 9 kN, which corresponds to the peak tire force that can be obtained in this example. If the VMM control unit 260 requests a further increase in tire force, for example to operating point 540, the tire will enter the nonlinear region 420 and the wheel speed will increase, resulting in a reduction in the tire force generated, which is undesirable in most situations. Notably, this reduction in the tire force generated is also seen as a reduction in the torque generated at the wheel axle, as long as the wheel speed remains at least constant for slowly changing vehicle speeds.

[0046] Figure 5 also shows what happens if friction suddenly decreases. In this case, the inverse tire model F x From F x’ Friction changes rapidly to 0. Assume the vehicle is accelerating and a given tire force is desired. To maintain this tire force after a change in operating conditions, an increase in wheel slip is required (510). However, an MSD actuator, such as an electric machine operating at a high control bandwidth and set to maintain a target wheel speed, will not spin out of control if friction suddenly decreases. To see this, consider two operating points 550 and 560. As friction decreases, the operating point also decreases, but because the vehicle speed changes relatively slowly due to the inertia involved and the wheel speed is maintained by the high bandwidth MSD actuator controller, there is no transition into the nonlinear region as there would be if the torque target were instead controlled by a high bandwidth MSD actuator controller.

[0047] This disclosure assumes that both the applied torque and the controlled wheel speed change much faster than the ground vehicle speed, and instead, the torque T currently applied by the MSD is ESTBy estimating the applied torque T and correlating the change in applied torque with the change in wheel or axle speed ω, the need for both an inverse tire model and accurate vehicle ground speed is eliminated. During propulsion with a positive generated torque, an increase in wheel speed ω increases the estimated applied torque T EST If the torque request results in a decrease in , it can be inferred that the peak 430 in the (unknown) inverse tire model has passed and entered the nonlinear region to the right of the peak. If this occurs, the controller immediately backs off and reduces the target wheel speed set in the MSD. Note that the MSD actuator always controls the wheel to maintain the set wheel speed, regardless of whether the torque request is negative or positive. Thus, even if road conditions change rapidly, the wheel will not suddenly increase its wheel slip as it would if the torque was set.

[0048] In summary, disclosed herein is a control unit 230 for controlling at least one torque generating MSD 220, 250, such as an electric machine, on a heavy vehicle 100. The control unit 230 controls a desired longitudinal tire force F generated by the torque generating MSD 220, 250. x A motion demand T, such as a torque demand or tire force demand, i 4 and 5, and without any knowledge of the ground speed of the vehicle 100. Rather, if the TSM function 270 wishes to accelerate or brake the vehicle, it can adapt the motion request accordingly.

[0049] The control unit 230 also calculates an estimated applied torque T EST For example, if the MSD 250 is an electric machine, the estimated applied torque T EST may be determined based at least in part on a motor current associated with the electric machine, as described below. ESTmay be obtained from an actuator control unit, which often implements an output port to provide this information in electrical or digital format to its controller. Interestingly, in the case where the MSD 250 is a wheel hub electric machine that includes an integrated electronic control unit (ECU), the ECU may also provide the estimated applied torque T EST As described above, the estimated applied torque T EST may also be obtained at least in part based on an output from a torque sensor, such as a mechanical strain force sensor. Thus, the control unit receives or determines the torque currently applied by the torque generating device. This torque can be either positive or negative. An electric machine can generate both positive and negative torque, whereas a friction brake can only generate negative torque. Of course, to estimate the torque generated by a friction brake, a torque sensor is required, unless the applied torque can be inferred from the applied brake pressure, which is often problematic to calibrate, but is possible in some cases. Torque estimation and torque sensors are described in more detail below.

[0050] Furthermore, the control unit 230 determines the motion demand T i and the estimated applied torque T EST based on, for example, the difference between the two, i Determine the torque generation MSD220, 250 and set the target wheel speed ω to the set level. iThe set wheel speed is maintained by the MSD actuator regardless of road friction conditions (and independent of vehicle speed). Thus, if a given wheel speed is set, for example by an electric machine, and the wheel subsequently encounters an ice patch, there is no or very little change in wheel speed because control of the MSD is based on the maintained target speed. This is a significant difference compared to the case where a wheel encountering low friction may spin out of control and enter the nonlinear region 420 if the MSD is set to maintain the target torque. The change in wheel speed is set by the control unit 230 based on the difference between the motion request and the current estimate of the applied torque. If the motion request calls for generating additional force, the wheel speed is increased in a controlled manner, i.e., by a step increase or a controlled continuous increase, while the estimated applied torque is monitored.

[0051] As an important concept of the present disclosure, the control unit 230 controls the set wheel speed ω i The increase in the estimated applied torque T EST When the target wheel speed ω i , the wheel speed is then configured to execute a back-off procedure that includes decreasing the estimated applied torque T. If this occurs, i.e., if an increase in wheel speed during positive torque development results in a decrease in the estimated torque, this most likely means that we have passed the peak 430 and entered the non-linear region 420 where the slope of the relationship between tire force and wheel slip is negative. Since this is most likely undesirable, the wheel speed is immediately backed off (e.g., by a predetermined amount). EST , and the changes in wheel speed are assumed to be well time synchronized, or at least approximately time synchronized, the level of synchronization depending on the rate at which the vehicle changes its ground speed, as well as any transient effects present in the estimated torque signal.

[0052] The vehicle state, i.e. its speed and acceleration, takes time to change due to the large mass of a large vehicle. On the other hand, the applied torque and wheel speed can be changed very quickly with modern actuators that are designed for high bandwidth operation. This means that the vehicle speed can be assumed to be nearly constant, or piecewise constant, while performing fast speed control at the wheels.

[0053] It will be appreciated that the above concepts may also be applied during braking, i.e., during the generation of negative torque by one or more torque generating MSDs. An exemplary inverse tire model 600 for negative applied torque is shown in FIG. 6, and it should be noted that it is, at least approximately, essentially a mirror version of the inverse tire model for propulsion. It also has a peak force 430 that separates the linear region 410 from the nonlinear region. In this case, the control unit 230 calculates the desired negative longitudinal tire force F generated by the torque generating MSDs 220, 250 as x A motion demand T i and receiving the set wheel speed ω i The decrease in the estimated applied torque T EST (upward on the y-axis in FIG. 6 ), the target wheel speed ω i immediately increases (to the right of the 4x-axis in Figure 6). In other words, the more braking, the smaller the braking force.

[0054] Regarding the details of torque estimation, it is noted that there are several methods known in the art for estimating the torque applied by an electric machine, such methods are outside the scope of this disclosure and will only be briefly described herein.

[0055] For example, in the case of a permanent magnet synchronous machine PMSM, the following relationship holds in many cases, at least approximately:

number

[0056] In “Accurate Torque Estimation for Induction Motors by Utilizing Globally Optimized Flux Observers”, 2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion SPEEDAM, 2020, pp. 219-226, M. Stender, O. Wallscheid and J. Bocker discuss torque estimation for induction motors.

[0057] US8080956B2 provides an example of how the applied torque can actually be estimated.

[0058] Of course, the torque applied to the axle can also be measured by a mechanical or electrical torque sensor. A torque sensor, also known as a torque transducer or torque meter, is a device for measuring, and possibly recording, the torque in a rotating system, such as the drive axle of the wheels 210. It is relatively easy to measure static torque. Dynamic torque, on the other hand, is not so easy to measure, since it generally requires the transfer of some effect, either electric or magnetic, from the shaft being measured to the static system. One way to achieve this is to coordinate the shaft, or a member attached to the shaft, with a series of permanent magnet domains. The magnetic properties of these domains vary in response to the applied torque, and can therefore be measured using a non-contact sensor.

[0059] Generally, torque sensors or torque transducers use strain gauges applied to a rotating shaft or axle. This method requires a means to power the strain gauge bridge as well as a means to receive signals from the rotating shaft. This may be accomplished using slip rings, radio telemetry, or rotary transformers. Newer types of torque transducers add electronics and A / D converters that coordinate with the rotating shaft. The stator electronics then read the digital signals and convert those signals to a high level analog output signal. Yet another method of measuring torque is by torsion angle or phase shift measurement, whereby the torsion angle resulting from an applied torque is measured by using two angular position sensors and measuring the phase angle between them.

[0060] The control unit 230 calculates the target wheel speed ω i and the estimated applied torque (T EST ) and the correspondingly set wheel speed (ω i) and optionally configured to determine, or at least approximate, a relationship between the torque generated by the torque generating MSD 220, 250 and the applied torque and the wheel speed. In a naive view, this relationship can be just a linear relationship between the applied torque and the wheel speed, conveying information about the linear region 410 of the current inverse tire model. Of course, polynomial models or other more advanced models can also be used. Filtering can be applied to reduce measurement noise. This relationship can be estimated from the wheel speed and estimated applied torque pair, for example, by fitting a model curve, such as a straight line, or by applying a model-based filter, such as a Kalman filter, particle filter, etc., as shown in example 1100 of FIG. 11, where crosses 1110 represent the estimated torque and wheel speed measurement pair and dashed line 1120 represents the fitted model curve. This fitted model is of course only valid for a given vehicle speed, but the VMM function 260, knowing the vehicle speed, can infer the true inverse tire model from this type of feedback data. According to one example, the control unit 230 is configured to output data indicative of the determined model as capability signals 231, 232 to the VMM control unit 260. The VMM control unit 260 may have information related to the speed of the vehicle and the radius of the wheels 210 and can therefore convert the model into an approximation of the current inverse tire model.

[0061] Estimated applied torque T EST is preferably compensated for one or more predetermined wheel and / or driveline characteristics, such as inertia and / or stiffness values. EST may be determined at least in part based on a predetermined electric machine windup characteristic. According to one example, the control unit 230 may determine the current generated tire force F x may be configured to estimate as follows:

number

number

[0062] The method described thus far avoids operation in the nonlinear region by backing off as soon as it determines that a change in wheel speed results in an undesired change in the estimated applied torque. For positive torque (propulsion), backing off is triggered when an increase in wheel speed results in a decrease in the estimated applied torque. For negative torque (braking), backing off is triggered when a decrease in wheel speed results in a decrease in the applied torque.

[0063] However, it will be appreciated that this concept can also be used to identify peaks in the current inverse tire model, such as peak 430 shown in Figure 4. To do this, and referring to Figure 7, the control unit 230 calculates the target wheel speed ω i (700) is changed to change the estimated applied torque T EST This allows the control unit to determine whether the slope of the inverse tire model is positive or negative about the nominal target wheel speed values ​​710, 720. The sign of the slope is a function of the estimated applied torque T EST That is, for positive torque, when a decrease in wheel speed results in a decrease in torque and an increase in wheel speed results in an increase in torque, the slope is positive, but if a decrease in wheel speed results in an increase in torque and an increase in wheel speed results in a decrease in applied torque, the slope is negative and the wheels 210 are likely operating within the non-linear region 420. Of course, the same mechanism can be used during braking, i.e., when the applied torque is negative. In this case, operation past the peak force is indicated by a decrease in application.

[0064] The methods disclosed herein can also be used to improve the feedback data 231, 232, 233 from the MSD control layer 230 to the VMM function 260. The control unit 230 may also provide feedback to the vehicle speed controller 260 based on the set wheel speed ω i The increase in the estimated applied torque T EST If the torque generation capacity is reduced, the applied torque T EST That is, when the back-off operation is triggered, the current estimated applied torque is most likely close to the maximum torque that a given MSD can generate. This value can then be communicated to higher layers, where it can be used as a capability in MSD cooperation.

[0065] When wheel speed backoff is triggered, it may also be advantageous to set an increased control bandwidth by the actuator controller to allow for a faster response to the unfolding event. The control bandwidth can often be set in the actuator controller, allowing the MSD control function 230 to determine how fast the actuators need to respond to its commands. This value is typically set as a trade-off between actuator responsiveness and other objectives such as energy efficiency and passenger comfort. The control unit 230 then determines the set wheel speed ω i The increase in the estimated applied torque T EST The control bandwidth may be configured to be increased if this results in a decrease in

[0066] 8 is a flow chart illustrating a method summarizing at least a portion of the preceding discussion. A computer-implemented method executed by a control unit 230 for controlling at least one torque generating motion support device (torque generating MSD) 220, 250 on a large vehicle 100 is illustrated, the method comprising: The desired positive longitudinal tire force F generated by the torque generating MSD 220, 250 x A motion demand T i (S1) receiving an estimated applied torque T indicating the current positive torque generated by at least one torque generating MSD 220, 250; EST (S2) exercise requirement T i and the estimated applied torque T EST Based on the target wheel speed ω i and (S3) determining Target wheel speed ω i Setting the torque generation MSD220, 250 so as to maintain (S4), Including, This method uses a set wheel speed ω i The increase in the estimated applied torque T EST When the target wheel speed ω i The method further includes performing a backoff procedure including reducing the bandwidth (S5).

[0067] FIG. 9 illustrates components of a control unit such as the VUC 130, 140, in terms of several functional units. The control unit may implement one or more of the above-mentioned functions of the TSM 270, the VMM 260, and / or the MSD control function 230 according to the embodiments described herein. The control unit is configured to perform at least some of the above-mentioned functions for the control of the heavy vehicle 100. The processing circuitry 910 is provided using any combination of one or more suitable central processing units (CPUs), multiprocessors, microcontrollers, digital signal processors (DSPs), etc. capable of executing software instructions stored in a computer program product in the form of a storage medium 920, for example. The processing circuitry 910 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0068] In particular, the processing circuitry 910 is configured to cause the control unit 101 to perform a set of operations or steps, such as the methods described in connection with Figure 9. For example, the storage medium 920 may store a set of operations, and the processing circuitry 910 may be configured to retrieve the set of operations from the storage medium 920 and cause the control unit 1100 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 configured to perform the methods disclosed herein.

[0069] Storage medium 920 may also include persistent storage, which may be any single or combination of, for example, magnetic memory, optical memory, solid-state memory, or even remotely mounted memory.

[0070] The control unit 1100 may further comprise an interface 930 for communicating with at least one external device. The interface 930 may thus include one or more transmitters and receivers, including analog and digital components, and an appropriate number of ports for wired or wireless communication.

[0071] The processing circuitry 910 controls the general operation of the control unit 1100, for example, by sending data and control signals to the interface 930 and the storage medium 920, by receiving data and reports from the interface 930, and by retrieving data and instructions from the storage medium 920. Other components and associated functions of the control node are omitted so as not to obscure the concepts presented herein.

[0072] Figure 10 shows a computer readable medium 1010 carrying a computer program comprising program code means 1020 for performing the method shown in Figure 8 when said program product is executed on a computer. The computer readable medium and the code means together may form a computer program product 1000.

Claims

1. A control unit (230) for controlling at least one torque generating motion support device (torque generating MSD) (220, 250) of a heavy vehicle (100), comprising: The control unit (230) The desired positive longitudinal tire force (F) generated by the torque generating MSD (220, 250) ｘ ) to indicate the motion demand (T ｉ ) and an estimated applied torque (T) indicative of a current positive torque generated by the at least one torque generating MSD (220, 250); ＥＳＴ ) and The motion demand (T ｉ ) and the estimated applied torque (T ＥＳＴ ) based on the target wheel speed (ω ｉ ) is determined, The target wheel speed (ω ｉ setting the torque generating MSD (220, 250) to maintain It is configured as follows: The control unit (230) controls the set wheel speed (ω ｉ ) increases with the estimated applied torque (T ＥＳＴ ) to cause a decrease in the target wheel speed (ω ｉ ).

2. The at least one MSD (250) includes an electric machine, and the estimated applied torque (T ＥＳＴ 2. The control unit (230) of claim 1, wherein the motor current associated with the electric machine is based at least in part on a motor current associated with the electric machine.

3. The estimated applied torque (T ＥＳＴ 3. The control unit (230) of claim 1 or 2, wherein the torque sensor (230) is based at least in part on an output from a torque sensor, such as a strain force sensor.

4. The at least one MSD (250) determines the estimated applied torque (T ＥＳＴ 4. A control unit (230) according to any one of claims 1 to 3, comprising a wheel hub electric machine including an integrated electronic control unit ECU configured to output a signal having the following characteristics:

5. The control unit (230) controls the target wheel speed (ω ｉ ) and the estimated applied torque (T ＥＳＴ ) and the correspondingly set wheel speed (ω ｉ 5. The control unit (230) of claim 1, configured to determine a relationship between the torque generated by the torque generating MSD (220, 250) based on a sequence of

6. The control unit (230) of claim 5, wherein the control unit (230) is configured to output data indicative of the determined model as a capability signal (231, 232).

7. The estimated applied torque (T ＥＳＴ 7. A control unit (230) according to any one of claims 1 to 6, wherein one or more predetermined wheel and / or drivetrain characteristics, such as predetermined or estimated inertia and / or stiffness values, are compensated for by the control unit.

8. The estimated applied torque (T ＥＳＴ 8. The control unit (230) of any one of claims 1 to 7, wherein the windup time is determined based at least in part on a predetermined electric machine windup characteristic.

9. Currently generated tire force F ｘ and further configured to estimate [0010] In the ceremony, T モータ is the determined motor torque, [0025] is the moment associated with the motor inertia, and f(Δθ ｏｓｃ 9. The control unit (230) according to any one of claims 1 to 8, wherein: ##EQU1## is the wind-up effect of the electric machine.

10. The target wheel speed (ω ｉ ) is varied (700), and the estimated applied torque (T ＥＳＴ The control unit (230) of any one of claims 1 to 9, configured to monitor a

11. The control unit (230) controls the set wheel speed (ω ｉ ) increases with the estimated applied torque (T ＥＳＴ ) is reduced, the current torque generating capacity is reduced by the estimated applied torque (T ＥＳＴ The control unit (230) of any one of claims 1 to 10, configured to set the metric as:

12. The control unit (230) controls the set wheel speed (ω ｉ ) increases with the estimated applied torque (T ＥＳＴ 12. The control unit (230) of any one of claims 1 to 11, configured to increase a set control bandwidth of the MSD actuator if a decrease in the control bandwidth results in a decrease in the MSD actuator's set bandwidth.

13. The control unit (230) controls a desired negative longitudinal tire force (F) generated by the torque generating MSD (220, 250). ｘ ) to indicate the motion demand (T ｉ ) configured to receive The control unit (230) controls the set wheel speed (ω ｉ ) is reduced by the estimated applied torque (T ＥＳＴ ) to cause an increase in the target wheel speed (ω ｉ The control unit (230) of any one of claims 1 to 12, configured to raise a

14. A heavy vehicle (100) comprising a control unit (130, 140) according to any one of the preceding claims.

15. A computer-implemented method executed in a control unit (230) for controlling at least one torque generating motion support device (torque generating MSD) (220, 250) in a heavy vehicle (100), comprising: The method further comprising: The desired positive longitudinal tire force (F) generated by the torque generating MSD (220, 250) ｘ ) to indicate the motion demand (T ｉ ) (S1); an estimated applied torque (T) indicative of a current positive torque generated by the at least one torque generating MSD (220, 250); ＥＳＴ ) (S2); The motion demand (T ｉ ) and the estimated applied torque (T ＥＳＴ ) based on the target wheel speed (ω ｉ ) (S3); The target wheel speed (ω ｉ setting the torque generating MSD (220, 250) to maintain the torque generating MSD (220, 250) (S4); Including, The method is carried out by adjusting the set wheel speed (ω ｉ ) increases with the estimated applied torque (T ＥＳＴ ) to cause a decrease in the target wheel speed (ω ｉ ) (S5).

16. A computer program comprising program code means for performing the steps according to claim 15 when the program is executed on a processing circuit (810) of a computer or a control unit (130, 140).

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