Vehicle motion management system and actuator control system for a vehicle

Abstract

The present disclosure relates to a vehicle motion management system and an actuator control system for a vehicle. The vehicle motion management system and actuator control system are arranged to control operation of at least one actuator configured to apply torque to at least one wheel of the vehicle. The vehicle motion management system is configured to transmit a control signal to the actuator control system, wherein the actuator control system is configured to generate an operational torque to be executed subject to a torque limit and a desired wheel speed constraint based on the control signal.

Description

Technical Field

[0001] This disclosure relates to a vehicle motion management system and an actuator control system for a vehicle. It also relates to a method and control signals operable via the vehicle motion management system and actuator control system. This disclosure is applicable to electrically propelled vehicles. While this disclosure will primarily relate to truck-type vehicles propelled by an electric motor, it is also applicable to other types of vehicles. Background Technology

[0002] In the vehicle sector, particularly in the low, medium, and heavy-duty vehicle segment commonly referred to as trucks, various vehicle control functions are constantly evolving. Specifically, these control functions aim to improve vehicle driving performance, driver comfort, and safety during operation.

[0003] WO 2017 / 215751 describes a system for improving, for example, overall vehicle stability. Specifically, WO 2017 / 215751 describes a wheel controller including a wheel capability module arranged to communicate with a tire model generator. The wheel capability module is arranged to determine longitudinal wheel force values ​​based on calculated wheel slip values.

[0004] The system described in WO 2017 / 215751 offers significant advantages, for example, in overall vehicle dynamics control. However, WO 2017 / 215751 still requires further improvement. In particular, it is desirable to be able to recover from the wheel slip control described in WO 2017 / 215751, thereby improving driving operation, for example, under different road conditions, namely driving operation on wet roads with normal to high friction between the wheels and the road surface, as well as operation on dry roads. Summary of the Invention

[0005] Therefore, the objective of this invention is to overcome at least part of the above-mentioned defects.

[0006] According to a first aspect, a vehicle motion management system for a vehicle is provided, which is connectable to an actuator control system to communicate control signals between the two, wherein the vehicle motion management system is configured to: obtain parameter values ​​related to a desired wheel force of at least one wheel of the vehicle; determine a torque limit of at least one wheel based on the parameter values ​​related to the desired wheel force; determine a mapping model based on the relationship between the wheel force and wheel speed of at least one wheel; determine parameter values ​​related to the desired wheel speed of at least one wheel based on the mapping model; and transmit control signals to the actuator control system, the control signals being arranged to cause the actuator control system to generate an operating torque to be executed, constrained by the torque limit and the desired wheel speed, when executed by the actuator control system.

[0007] The vehicle motion management system and actuator control system are the vehicle's control systems, each arranged to perform various control functions for controlling vehicle operation, particularly for controlling wheel operation. The vehicle motion management system is preferably configured to receive and determine wheel parameters at a higher level; that is, the vehicle motion management system determines, in a more general form, the desired torque and wheel slip limits, also known as tire slip limits. The actuator control system is arranged as a lower-level control system, configured to translate the parameters received from the vehicle motion management system into appropriate parameters for the actuators. The actuator control system considers, for example, the current drivetrain state before forwarding actuator signals to the actuators. The current drivetrain state may, for example, relate to the current state of the vehicle's transmission, such as the gear stage or the actuation state of the transmission clutch.

[0008] The parameter values ​​related to the desired wheel force (also known as tire force) should be interpreted as being related to both the desired wheel force and the desired wheel torque. Therefore, the desired wheel force / torque is obtained in the form of a force / torque demand signal. The parameter values ​​related to the desired wheel force can be based on requests from the vehicle operator, i.e., the position of the accelerator or brake pedal, or on force demand signals from systems that autonomously control the vehicle's propulsion operations or from advanced driver assistance systems (ADAS). The torque limit can be determined based on the desired wheel force combined with a margin value. Therefore, the torque limit is set to a value corresponding to the desired torque plus a predetermined safety margin. Alternatively, the torque limit can be based on a torque request from the vehicle operator.

[0009] Furthermore, the parameter values ​​related to the desired wheel speed should be interpreted as also being related to the desired wheel slip of at least one wheel of the vehicle. Wheel slip is the relative longitudinal movement between the vehicle wheel and the ground, i.e., the amount of "slippage," which is the difference between the wheel's ground speed and the actual wheel speed. Taking into account the wheel radius, wheel slip can be determined as the relationship between the wheel's longitudinal speed and its rotational speed. Thus, wheel slip is a parameter value related to wheel speed and is preferably defined in a wheel-based coordinate system.

[0010] Furthermore, according to an example embodiment, a mapping model based on predetermined characteristic values ​​of at least one wheel defines the relationship between wheel force and wheel speed. Wheel speed can be defined and normalized relative to the ground, i.e., wheel slip, or defined as absolute rotational speed. Therefore, by defining the mapping model, a wheel force value for a specific wheel speed value can be obtained.

[0011] The mapping model can be a fixed mapping model, and / or a mapping model that includes estimated features of the relationship between wheel forces and wheel speeds. As an alternative, the mapping model can be parameterized based on other factors, such as tire normal load, tire type, wear, friction, etc.

[0012] By defining and transmitting control signals indicating torque limits, the vehicle can operate in both a torque limit-based control mode and a speed-based control model, depending on actual road conditions. Thus, when the actuator generates operating torque based on the desired wheel speed, the torque limit will not be exceeded. Therefore, the mapping model can preferably be defined to correspond to relatively slippery road conditions, i.e., wet asphalt or icy roads. By setting such a mapping model, the actuator will operate in torque limit control mode, for example, when driving on dry roads, because the applied torque will reach the torque limit. On the other hand, when operating the vehicle with large steering inputs (i.e., high lateral acceleration) on, for example, slippery roads or dry roads, the torque limit will not be reached, and the actuator will operate in wheel speed control mode.

[0013] According to an example embodiment, the mapping model can be based on the relationship between wheel force and wheel speed for predetermined wheel characteristics of at least one wheel. As mentioned above, the predetermined wheel characteristics can be, for example, wheel normal load, friction between the wheel and the ground, the specific type of tire, etc. Therefore, the mapping model can be modified based on various parameters.

[0014] According to an example embodiment, the mapping model can be based on safety parameters that indicate the current operating conditions of the vehicle. As mentioned above, the mapping model can be based on relatively slippery road conditions. Thus, the safety parameters enable the actuator to be controlled primarily in torque limit control mode, and only in wheel speed control mode when road conditions are "slipperier" than considered by the safety parameters.

[0015] According to the example embodiment, and as described above, the parameter related to the desired wheel speed can be the desired wheel slip parameter.

[0016] According to the example embodiment, the torque limit can be determined independently of the determined mapping model. The advantage is that the mapping model can be based on, for example, slippery road conditions or any of the other factors mentioned above, and the torque limit can be freely determined according to, for example, the desired driving experience.

[0017] According to an example embodiment, the mapping model may be a first mapping model, and the vehicle motion management system is configured to determine a second mapping model, which is based on an increased wheel force compared to the first mapping model used for the corresponding wheel speed.

[0018] According to an example embodiment, the torque limit may be a first torque limit, and the vehicle motion management system is configured to determine a second torque limit related to the desired wheel speed based on a second mapping model, wherein the transmitted control signal is arranged to cause the actuator control system to generate an operating torque to be executed, constrained by the desired wheel speed and the first and second torque limits, when executed by the actuator control system.

[0019] Using the first and second mapping models, a range can be defined, where one mapping model represents, for example, slippery road conditions, while the other mapping models represent, for example, road conditions with relatively high friction between the wheel surface and the road surface. Therefore, the applied torque will not exceed the upper torque limit and will not fall below the lower torque limit.

[0020] According to an example embodiment, the first and second mapping models can be determined based on a predetermined range between wheel force values ​​at a specific wheel speed.

[0021] The predetermined range can be based on the desired torque, where the range is set based on this desired torque, namely, an upper safety margin and a lower safety margin. More specifically, the upper torque limit can correspond to the desired torque plus a predetermined torque value, while the lower torque limit corresponds to the desired torque minus the predetermined torque value.

[0022] According to a second aspect, an actuator control system for a vehicle is provided, the actuator control system being connectable to a vehicle motion management system and at least one actuator configured to apply torque to at least one wheel of the vehicle, wherein the actuator control system is configured to: receive a control signal from the vehicle motion management system indicating a torque limit for the actuator and a parameter value related to a desired wheel speed; and transmit an actuator signal to the actuator to cause the actuator to generate an operating torque on at least one wheel constrained by the torque limit and the parameter value related to the desired wheel speed.

[0023] Therefore, the actuator control system of the second aspect receives the control signals described above with respect to the first aspect. The advantage of using an actuator control system to control parameters related to wheel speed (such as wheel slip) is that the actuator control system can reject rapidly changing disturbances in the vehicle system. For example, when operating the vehicle on rough roads, wheel slip can be kept within a substantially safe slip range. The effect of the second aspect is similar to that described above.

[0024] According to an example embodiment, the actuator signal can be configured to control the actuator to generate operating torque without exceeding a torque limit. According to another example, the actuator signal can be configured to control the actuator to generate operating torque higher than the torque lower limit described above with respect to the first aspect.

[0025] According to an example embodiment, the actuator control system can be configured to generate operating torque based on the current state of the vehicle's drivetrain.

[0026] The current drivetrain state should be interpreted as the current operating mode of the drivetrain (particularly the transmission). According to an example embodiment, the current vehicle drivetrain state can be one of the current vehicle transmission states, such as the gear position or transmission clutch actuation state. Therefore, and as described above, the actuator control system is arranged as a lower-level control system configured to take into account the current drivetrain state and convert parameters received from the vehicle motion management system into appropriate parameters for the actuator.

[0027] According to an example embodiment, the actuator control system may be a distributed actuator control system that can be connected to a wheel-specific actuator configured to control a single wheel of a vehicle.

[0028] Using a distributed actuator control system enables rapid responses to the specific actuators it is connected to, thus improving the vehicle's maneuverability in terms of propulsion and braking. A distributed actuator control system can be connected to a separate vehicle motion management system, or to a central vehicle motion management system that connects to multiple distributed actuator control systems.

[0029] The further effects and features of the second aspect are largely similar to those described above regarding the first aspect.

[0030] According to a third aspect, a method for controlling an actuator of a vehicle is provided, the actuator being configured to apply torque to at least one wheel of the vehicle, wherein the method includes: determining parameter values ​​related to a desired wheel force of at least one wheel of the vehicle; determining a torque limit of at least one wheel based on the parameter values ​​related to the desired wheel force; determining a mapping model based on a relationship between the wheel force and wheel speed of at least one wheel; determining parameter values ​​related to the desired wheel speed of said at least one wheel based on the mapping model; and controlling the actuator to generate an operating torque on said at least one wheel constrained by the torque limit and the parameter values ​​related to the desired wheel speed.

[0031] The various operations performed by the methods of the third aspect should not be construed as necessarily requiring execution by a particular one of the aforementioned vehicle motion management system or actuator control system. Rather, unless otherwise stated, these operations may be performed by either the vehicle motion management system or the actuator control system.

[0032] According to the fourth aspect, a control signal is provided representing an instruction to be executed by an actuator control system of a vehicle, the control signal including: a wheel speed component, representing the instruction, which, when executed by the actuator control system, causes the actuator control system to generate a parameter value associated with a desired wheel speed of the vehicle's wheels; and a torque limit component, representing the instruction, which, when executed by the actuator control system, causes the actuator control system to generate a maximum permissible torque limit of the vehicle's wheels; wherein the actuator control system is adapted to execute an operating torque constrained by the desired wheel speed and the maximum permissible torque limit.

[0033] According to a fifth aspect, a computer program is provided that includes program code means for performing the steps of the third aspect when the program is run on a computer.

[0034] According to a sixth aspect, a computer-readable medium carrying a computer program is provided, the computer program including program means for performing the steps of the third aspect when the program means are run on a computer.

[0035] The effects and characteristics of the third, fourth, fifth, and sixth aspects are largely similar to those described above regarding the first and second aspects.

[0036] Further features and advantages will become apparent as the claims are examined and the following description is provided. Those skilled in the art will recognize that different features can be combined to produce embodiments other than those described below, without departing from the scope of this disclosure. Attached Figure Description

[0037] The above and additional objectives, features, and advantages will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments, wherein:

[0038] Figure 1 This is a side view illustrating an example embodiment of a vehicle in the form of a truck;

[0039] Figure 2 This is a schematic diagram of a vehicle motion management system and an actuator control system according to an example embodiment;

[0040] Figure 3 This is a graph illustrating an example embodiment of a model representing the relationship between wheel slippage and tire force;

[0041] Figure 4 This is a graph illustrating a further example embodiment of a model representing the relationship between wheel slippage and tire force;

[0042] Figure 5A graph illustrating a further example embodiment of a model representing the relationship between wheel slippage and tire force; and

[0043] Figure 6 It is for control according to the example embodiment Figure 1 A flowchart of a method for manufacturing a vehicle actuator. Detailed Implementation

[0044] This disclosure will now be described more fully below with reference to the accompanying drawings, in which illustrative embodiments are shown. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Throughout the description, the same reference numerals refer to the same elements.

[0045] Special Reference Figure 1 The image depicts a truck-type vehicle 100. The vehicle includes multiple wheels 102, each wheel 102 including a corresponding actuator 104. Although... Figure 1 The embodiments depicted show an actuator for each wheel 102; however, it should be readily understood that, for example, a pair of wheels 102 could be arranged without such an actuator 104. Furthermore, the actuator 104 is preferably an actuator for generating torque on the respective wheels of the vehicle or for both wheels of the axle. The actuator can be a propulsion device, such as a motor 106 arranged to provide longitudinal wheel force to the wheels of the vehicle 100, as... Figures 3 to 5 As shown and further described below, such a motor can thus be adapted to generate propulsive torque and be configured in regenerative braking mode to charge the vehicle 100's battery (not shown) or other energy storage system. The motor can also generate braking torque without storing energy. For example, excess energy from the motor can be dissipated during braking using a brake resistor or similar device.

[0046] Furthermore, each actuator 104 is connected to a corresponding actuator control system 300 arranged to control the operation of the actuator 104. The actuator control system 300 is preferably a distributed motion support system 300, although a centralized implementation is also possible. It should also be understood that some parts of the actuator control system can be implemented on processing circuitry remote from the vehicle, such as on a remote server 1000 accessible from the vehicle via a wireless link. Further, each actuator control system 300 is connected to the vehicle motion management system 200 of the vehicle 100 via a data bus communication arrangement 114, which can be wired, wireless, or both. Thus, control signals can be transmitted between the vehicle motion management system 200 and the actuator control system 300. Reference will be made below. Figure 2 The vehicle motion management system 200 and the actuator control system 300 are described in further detail.

[0047] The vehicle motion management system 200 and actuator control system 300 may include a microprocessor, microcontroller, programmable digital signal processor, or other programmable device. The system may also include, or alternatively include, application-specific integrated circuits, programmable gate arrays or programmable array logic, programmable logic devices, or digital signal processors. Where the system includes a programmable device such as a microprocessor, microcontroller, or programmable digital signal processor as described above, the processor may further include computer-executable code that controls the operation of the programmable device.

[0048] refer to Figure 2 , Figure 2 This is a schematic diagram of a vehicle motion management system 200 and an actuator control system 300 according to an example embodiment. Therefore, the vehicle motion management system 200 and the actuator control system 300 form part of the vehicle motion system 500.

[0049] The entire vehicle control system 500 can be implemented on one or more vehicle unit computers (VUCs). The VUCs can be configured to execute vehicle control methods organized according to a hierarchical functional architecture, wherein some functions can be included in the traffic conditions management (TSM) domain at a higher level, and some other functions can be included in the vehicle motion management (VMM) domain residing in a lower functional layer.

[0050] Figure 2 This diagram schematically illustrates the function of controlling one or more wheels via example actuator control systems (ACS), such as friction brakes and propulsion devices. Friction brakes and propulsion devices are examples of wheel torque generating devices, which can also be referred to as actuators and can be controlled by one or more actuator control units. Control is based on measurement data obtained, for example, from wheel speed sensors and other vehicle state sensors (such as radar sensors, lidar sensors) and vision-based sensors (such as camera sensors and infrared detectors). Other example torque-generating motion support devices that can be controlled according to the principles discussed herein include engine retarders and power steering systems. ACS control units can be arranged to control one or more actuators. For example, it is not uncommon for an ACS control unit to be arranged to control two wheels on a given axle, for example, via a differential.

[0051] The TSM function plans driving maneuvers within a timeframe of approximately 10 seconds. This timeframe corresponds, for example, the time it takes for a vehicle to navigate a curve. Vehicle maneuvers planned and executed by the TSM can be correlated with acceleration and curvature curves describing the desired vehicle speed and cornering for a given maneuver. The TSM continuously requests the desired acceleration curve from the VMM function. reqand curvature curve c req The VMM performs the allocation of functions to satisfy TSM requests in a safe and robust manner.

[0052] Acceleration and curvature curves can also be obtained from the driver of a heavy vehicle via conventional control input devices such as the steering wheel, accelerator pedal, and brake pedal.

[0053] The VMM function operates over a timeframe of approximately one second, continuously translating the acceleration curve areq and curvature curve creq into control commands for controlling vehicle motion functions, actuated by different ACS of vehicle 100. These ACS report their capabilities to the VMM, which in turn uses them as constraints in vehicle control. The VMM function performs vehicle state or motion estimation; that is, it continuously determines the vehicle state by monitoring the operation of various sensors arranged on vehicle 100, including the position, velocity, acceleration, and articulation angle of different units in the vehicle assembly, typically but not always related to the ACS.

[0054] The results of motion estimation, i.e., the estimated vehicle state, can be input into the force generation module. The force generation module determines the global force required by different vehicle units based on the requested acceleration curve a. req and curvature curve c req The vehicle is moved to 100. The required global force vector is input to the ACS coordination function, which distributes wheel forces and coordinates other ACS, such as steering and suspension. The coordinated ACS then work together to provide the desired lateral force on the vehicle unit. y and longitudinal F x Force, and the required torque M z In order to obtain the desired motion of the vehicle combination.

[0055] By using, for example, a GPS, vision-based sensors, wheel speed sensors, radar sensors, and / or lidar sensors to determine the motion of a vehicle unit, and converting that motion into a local coordinate system for a given wheel (in terms of, for example, longitudinal and lateral rate components), wheel slip can be accurately estimated by comparing the motion of the vehicle unit in the wheel reference coordinate system with data obtained from wheel speed sensors arranged in connection with the wheel.

[0056] The mapping model, also known as the tire model, will combine the following Figures 3 to 5 A more detailed discussion can be made regarding the desired longitudinal tire force F. xiThe conversion between wheel speed and wheel slip is explained. Wheel slip involves the difference between wheel rotational speed and ground speed, which will be discussed in more detail below. Wheel speed is the rotational speed of the wheel, given in units such as revolutions per minute (rpm) or angular velocity in radians per second (ad / s) or degrees per second (deg / s).

[0057] Here, the tire model is a model of wheel behavior that describes the wheel forces generated as a function of wheel slip in the longitudinal direction (along the rolling direction) and / or the lateral direction (orthogonal to the longitudinal direction). The fundamentals of the tire model are covered in Hans Pacejka's "Tyre and vehicle dynamics," Elsevier Ltd. 2012, ISBN 978-0-08-097016-5. See, for example, Chapter 7, which discusses the relationship between wheel slip and longitudinal forces.

[0058] In summary, the VMM (Vehicle Management Model) manages both force generation and ACS (Autonomous System Coordination), determining which forces the vehicle unit needs to satisfy requests from the TSM (Transportation Management System) functions, such as accelerating the vehicle according to a requested acceleration curve from the TSM, and / or generating specific curvature motions of the vehicle also requested by the TSM. These forces may include, for example, yaw moment M. z Longitudinal force F x and lateral force F y And the different types of torque applied to different wheels.

[0059] The VMM is arranged as a higher-level control system, while the ACS is arranged as a lower-level control system. Thus, as will be described below, the higher-level VMM 200 is arranged to determine various parameters in the vehicle / wheel domain, i.e., based on overall vehicle conditions such as vehicle speed. On the other hand, the lower-level ACS 300 is arranged to determine parameters specific to the actuators connected to the wheels. Therefore, taking into account, for example, gear ratio, transmission inertia, etc., the signals received from the higher-level VMM by the lower-level ACS are converted into actuator domain parameters.

[0060] According to a non-limiting example, the vehicle motion management system 200 includes a torque module 202, a mapping module 204, and a wheel speed module 206. The vehicle motion management system 200 is further arranged to receive vehicle operation signals 502, which include data for operation on the vehicle motion management system 200 and its various modules 202, 204, 206. For example, the vehicle operation signals 502 provided to the vehicle motion management system 200 may include data in the form of signals indicating parameter values ​​related to the desired wheel force of at least one wheel of the vehicle, the vehicle's current environment, current traffic conditions, vehicle weight parameters, such as whether the vehicle is fully loaded, empty, partially loaded, and / or the topology of the road the vehicle is currently traveling on. The vehicle motion management system 200 may also receive other signals indicating specific vehicle conditions, such as current vehicle operating conditions, as described below. The torque module 202, mapping module 204, and wheel speed module 206 are configured to transmit communication signals to each other; that is, the different modules are configured to communicate with each other, as will be apparent from the following disclosure. It should be readily understood that the torque module 202, mapping module 204, and wheel speed module 206 are shown as separate components for illustrative purposes only. The vehicle motion management system 200 may, of course, simply include the various control functions themselves that perform the functions described below.

[0061] The functional operation of the vehicle motion management system 200 will now be described. Specifically, the vehicle motion management system 200 is configured to obtain parameter values ​​related to the desired wheel force of at least one wheel 102 of the vehicle. This parameter is preferably provided as data included in the aforementioned vehicle operation signal 502 and is preferably received by the torque module 202. This parameter should be interpreted as the desired wheel force and / or desired wheel torque, based on a requested demand from, for example, a vehicle operator, an autonomous vehicle control system, an ADAS system, etc. In the case of a demand requested by the vehicle operator, the signal may be based on the accelerator pedal position or the brake pedal position.

[0062] Based on parameter values ​​related to the desired wheel force, torque module 202 determines the torque limit of at least one wheel 102. (See below for reference.) Figure 5 The description further details the various alternatives for determining the torque limit.

[0063] In addition, mapping module 204 is configured to determine the mapping model (see example...) Figure 3 and 4 (402 in the model), the mapping model defines the relationship between wheel force and wheel speed of at least one wheel 102. The wheel speed can be defined and normalized relative to the ground, i.e., wheel slip, or defined as absolute rotational speed.

[0064] Therefore, the mapping model defines the longitudinal wheel force at a specific wheel speed and can be based on estimated characteristics of the relationship between wheel force and wheel speed. For example, the mapping model can be based on the assumption of a wet road surface, where the wheel force at a specific wheel speed is lower compared to the wheel force at the same wheel speed on a dry road surface. The mapping model can also be based on the normal load exposed to the tire, the specific tire currently in use, the expected wear of the tire, the estimated level of friction between the tire and the road surface, etc. According to a further example, the mapping model can also be based on predetermined characteristic values ​​of at least one wheel, the relationship between wheel force and wheel speed for predetermined wheel characteristics of at least one wheel, and safety parameters indicating the current operating conditions of the vehicle.

[0065] Based on the mapping model determined by mapping module 204, wheel speed module 206 is configured to determine parameter values ​​related to the desired wheel speed of at least one wheel 102 of vehicle 100. The parameters related to the desired wheel speed may correspond to either the desired wheel speed or the desired wheel slip. Therefore, when the desired wheel force is obtained, wheel speed module 206 can use the mapping model to map that wheel force to the desired wheel speed / wheel slip.

[0066] Once the torque limit and desired wheel speed have been determined, the vehicle motion management system 200 transmits a control signal 550, including data indicating the torque limit and desired wheel speed, to the actuator control system 300.

[0067] Therefore, the actuator control system 300 receives a control signal 550 from the vehicle motion management system 200. As described above, the control signal indicates the torque limit and parameter value related to the desired wheel speed of the actuator. Subsequently, the actuator control system 300 transmits an actuator control signal 590 to the actuator 104 to control its operation, specifically to control the actuator 104 to generate operating torque on at least one wheel to achieve the desired wheel speed but not exceeding the torque limit.

[0068] Therefore, during vehicle 100 operation, actuator 104 will operate in torque limit control mode, for example, when driving on a dry road, because the applied torque will reach the torque limit, while when driving on a wetter road, actuator 104 will operate in wheel speed control mode, because the torque limit will not be reached.

[0069] The actuator control system 300 can also be arranged to obtain a signal indicating the current transmission system state of the vehicle 100. The current transmission system state may, for example, involve the current state of the vehicle's transmission, the gear position of the vehicle's transmission, the actuation state of the transmission clutch, etc. Therefore, the operating torque determined by the actuator control system 300 can also be based on the current transmission system state.

[0070] To present exemplary embodiments of this disclosure, reference is made to... Figures 3 to 5 , Figures 3 to 5 Graphs depicting various examples of models representing the relationship between wheel slippage and tire force are shown. Figures 3 to 5 In each figure, the vertical axis 340 represents the tire force generated between the surface supporting wheel 102 and wheel 102, while the horizontal axis 330 represents the longitudinal wheel slip of wheel 102. It should be observed that the X-axis, which defines the longitudinal wheel slip, should be interpreted as also related to the longitudinal wheel speed, since wheel slip is a parameter value related to wheel speed. Furthermore, Figures 3 to 5 The description depicts a propulsion scenario, where the tire force is positive. This disclosure also applies to scenarios where the tire force is negative, i.e., during deceleration, which would correspond to... Figures 3 to 5 A graph in which the X and Y axes are mirror images.

[0071] First refer to Figure 3 , Figure 3 This is a graph illustrating a first example embodiment of a model representing the relationship between wheel slippage and tire force. As shown by the dashed line, mapping model 402 is determined based on any of the examples described above. Figure 3 It also depicts an actual tire model 404, which shows the actual relationship between wheel slip and tire force, and a prospective model 406 for dry roads and virtually unused tires, where the tire has excellent grip on the road surface.

[0072] Therefore, mapping model 402 corresponds to a more slippery expected condition compared to the "perfect" condition of the model indicated by reference numeral 406. A torque limit is set, indicated by reference numeral 412. Thus, the torque limit is converted into a tire force limit 412. Furthermore, a slip limit 410 is generated, thereby preventing the wheel from exceeding this slip limit.

[0073] like Figure 3 As shown, the actual tire model 404 is positioned above the mapped model 402, meaning the actual tire force for a particular wheel slip is actually higher than the tire force of the generated mapped model 402. Therefore, the vehicle is more likely to operate on dry surfaces and / or without significant steering input. The actuator 104 is controlled to generate torque for operating the vehicle at the desired wheel speed / wheel slip 408. Figure 3 In the example, actuator 104 will operate at torque limit 412 because the requested wheel slip will not be achieved when driving on a relatively dry surface. Therefore, in Figure 3 In the scenario shown, actuator 104 will operate in torque limit control mode. Consequently, the operator of vehicle 100 will receive the torque requested by him / her, and the vehicle will operate under relatively smooth steady-state conditions.

[0074] Refer to the example illustrating another operational scenario. Figure 4 .like Figure 4 As shown, the actual tire model 404 is located below the mapped model 402, meaning the actual tire force for a particular wheel slippage is actually lower than the tire force of the generated mapped model 402. Therefore, the vehicle is likely to operate on slippery roads and / or with large steering inputs (i.e., subjected to high lateral forces). This is consistent with the above regarding... Figure 3 In a similar manner, actuator 104 is controlled to generate torque for operating the vehicle at a desired wheel speed / wheel slip 408. However, since the actual tire model 404 is located below the generated mapped model 402, the desired wheel speed / wheel slip 408 will be reached before the actuator reaches its torque limit 412. Specifically, the torque limit 412 will not be reached and actuator 104 will operate in wheel speed control mode. In this case, wheel slip will be controlled proportionally to the driver's request, and vehicle stability will be maintained.

[0075] Therefore, vehicle 100 can be based on Figure 3 The example operation is that actuator 104 operates in torque limit control mode, and when the vehicle suddenly drives over an ice belt, vehicle 100... Figure 4 The example operation is that actuator 104 operates in wheel speed control mode. Therefore, a rapid change from torque limit control mode to wheel speed control mode is achieved without any interaction from vehicle motion management system 200.

[0076] Now for reference Figure 5 It shows a graph of a further example embodiment of a model representing the relationship between wheel slippage and tire force. In particular, Figure 5 The use of the lower 402' and upper 402" mapping models is described. The lower mapping model 402' represents, for example, wet and slippery road conditions, while the upper mapping model 402" represents, for example, dry road conditions. More specifically, for a given wheel slip value, the tire force of the upper mapping model 402" is higher than that of the lower mapping model 402'.

[0077] Actuator 104 is controlled to generate torque for operating vehicle 100 at a desired wheel speed / wheel slip 408 in a manner similar to that described above. However, the actuator torque is not permitted to exceed the upper torque limit 412" defined by the upper mapping model 402", or fall below the lower torque limit 412' defined by the lower mapping model 402'. Torque request 409 is... Figure 5 The example is depicted as being located somewhere between the upper limit 412” and the lower limit 412’.

[0078] The upper torque limit 412” and the lower torque limit 412’ are defined for a given wheel speed / wheel slip according to the upper 402” and lower 402’ mapping models, respectively, and can be selectively adjusted by further equations. Two alternatives to this adjustment are shown in equations (1)-(2) and (3)-(4). Equations (1)-(2) adjust the above torque limits based on a predetermined margin value (i.e., the value of the minimum operating band required to perform wheel speed control), while equations (3)-(4) adjust the torque limits based on a functional safety torque value (i.e., the safe value of the maximum operating band around any given torque request) considering vehicle safety.

[0079] T mi n = min(T) 412 ′, T req -T margin (1)

[0080] T max =max(T) 412″ T req +T margin (2)

[0081] T min =max(T) min T req -T funcSafety (3)

[0082] T max =min(T) min T req +T funcSafety (4)

[0083] in:

[0084] T req It is the requested torque; and

[0085] T min That is the predetermined minimum torque.

[0086] Equations (1)-(2) are preferably applicable to operating conditions with low wheel slip, because otherwise, T for low wheel slip min and T max They will be essentially the same. Equations (3) and (4) include the operator T. funcSafety Operator T funcSafety Torque is torque that takes into account vehicle functional safety (such as vehicle speed, vehicle weight, etc.).

[0087] Alternatively, one could consider other options for determining the upper and lower limits of torque, such as limiting the lower limit of torque to the requested torque minus the torque margin, and limiting the upper limit of torque to the requested torque plus the torque margin, without considering the mapping model.

[0088] In summary, for reference Figure 6 This is a flowchart of a method for controlling the aforementioned actuator 104. As described above, parameter values ​​related to the desired wheel force (such as desired wheel torque) of at least one wheel 102 of the vehicle 100 are determined in S1. The desired wheel force can be determined based on requests from, for example, a vehicle operator, a system for autonomous vehicle control, an ADAS system, etc. Based on the desired wheel force, torque limit 412 is determined in S2.

[0089] In addition, such as Figures 3 to 5 As described, mapping model 402 for S3 is determined based on the relationship between wheel force and wheel speed. Furthermore, based on mapping model 402, parameter values ​​for S4 related to the desired wheel speed of at least one wheel 102 are determined, thereby controlling actuator 104 for S5 to generate operating torque on at least one wheel. The operating torque is constrained by the determined torque limit and the desired wheel speed, meaning that the operating torque is therefore not allowed to exceed the torque limit.

[0090] It should be understood that this disclosure is not limited to the embodiments described above and shown in the accompanying drawings; rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of the appended claims.

Claims

1. A vehicle motion management system (200) for a vehicle, the vehicle motion management system (200) being connectable to an actuator control system (300) to communicate control signals between the two, wherein, The vehicle motion management system is configured to: - Obtain parameter values ​​related to the desired longitudinal wheel force of at least one wheel of the vehicle; - Determine a first torque limit for the at least one wheel based on the parameter values ​​related to the desired longitudinal wheel force; - Based on the estimated characteristics of the relationship between the longitudinal wheel force and the wheel speed of the at least one wheel, a mapping model is determined, wherein the mapping model is a first mapping model; - Determine a second mapping model, which is based on an increased longitudinal wheel force compared to the first mapping model for the corresponding wheel speed, wherein the first mapping model and the second mapping model are determined based on a predetermined range between longitudinal wheel force values ​​for a specific wheel speed; - Based on the second mapping model, determine the second torque limit related to the desired wheel speed; - Based on the first mapping model and the second mapping model, determine parameter values ​​related to the desired wheel speed of the at least one wheel; and - A control signal is transmitted to the actuator control system (300), the control signal being arranged to cause the actuator control system (300) to generate an operating torque to be executed, constrained by the desired wheel speed and the first torque limit and the second torque limit, when executed by the actuator control system (300).

2. The vehicle motion management system (200) according to claim 1, wherein, The first mapping model is based on the relationship between longitudinal wheel force and wheel speed for predetermined wheel characteristics of the at least one wheel.

3. The vehicle motion management system according to claim 1, wherein, The first mapping model is based on safety parameters that indicate the current operating conditions of the vehicle.

4. The vehicle motion management system according to claim 1, wherein, The parameter associated with the desired wheel speed is the desired wheel slip parameter.

5. The vehicle motion management system according to claim 1, wherein, The first torque limit is determined independently of the established first mapping model.

6. An actuator control system (300) for a vehicle, the actuator control system (300) being connectable to a vehicle motion management system (200) according to claim 1 and at least one actuator configured to apply torque to at least one wheel of the vehicle, wherein, The actuator control system (300) is configured to: - Receive control signals from the vehicle motion management system (200), the control signals indicating a first torque limit and a second torque limit for the actuator and parameter values ​​related to the desired wheel speed; and - Transmit actuator signals to the actuator to cause the actuator to generate an operating torque on the at least one wheel that is constrained by the first torque limit and the second torque limit and the parameter value related to the desired wheel speed.

7. The actuator control system (300) according to claim 6, wherein, The actuator signal is configured to control the actuator to generate operating torque without exceeding the first torque limit and the second torque limit.

8. The actuator control system (300) according to claim 6, wherein, The actuator control system (300) is configured to generate the operating torque based on the current vehicle drivetrain state of the vehicle.

9. The actuator control system (300) according to claim 6, wherein, The actuator control system (300) is a distributed actuator control system (300) that can be connected to a wheel-specific actuator configured to control a single wheel of the vehicle.

10. A method for controlling an actuator of a vehicle, said actuator being configured to apply torque on at least one wheel (104) of the vehicle, wherein, The method includes: - Determine (S1) the parameter values ​​related to the desired longitudinal wheel force of at least one wheel of the vehicle; - Based on the parameter values ​​related to the desired longitudinal wheel force, determine (S2) a first torque limit for the at least one wheel; - Based on the estimated characteristics of the relationship between the longitudinal wheel force and the wheel speed of the at least one wheel, determine the (S3) mapping model, wherein the mapping model is the first mapping model; - Determine a second mapping model, which is based on an increased longitudinal wheel force compared to the first mapping model for the corresponding wheel speed, wherein the first mapping model and the second mapping model are determined based on a predetermined range between longitudinal wheel force values ​​for a specific wheel speed; - Based on the second mapping model, determine the second torque limit related to the desired wheel speed; - Based on the first mapping model and the second mapping model, determine (S4) parameter values ​​related to the expected wheel speed of the at least one wheel; and - Control (S5) the actuator to generate an operating torque on the at least one wheel that is constrained by the parameter values ​​related to the desired wheel speed and the first torque limit and the second torque limit.

11. A computer program including program code means for performing the steps of claim 10 when the program is run on a computer.

12. A computer-readable medium carrying a computer program, the computer program including program means for performing the steps of claim 10 when the program means are run on a computer.

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