motor vehicle

Abstract

Motor vehicle (10) comprising: a first drive axle (119F) connected to a first set of wheels (15F); a second drive axle (119R) connected to a second set of wheels (15R); a plurality of torque actuators (25, 26, 114E, 14-1, 14-2, 200) each connected to the first drive axle (119F) or the second drive axle (119R) and configured to transmit corresponding output torques (TO) to the first drive axle (119F) and / or the second drive axle (119R), wherein the plurality of torque actuators (25, 26, 114E, 14-1, 14-2, 200) comprises multiple rotating electric machines (114E); a mode selection device (22M);and a main controller (50) connected to the plurality of torque actuators (25, 26, 114E, 14-1, 14-2, 200), the main controller (50) being programmed with a calibrated set of constraints (51C) and configured to: receive (B102) a set of vehicle inputs (CCI) specifying an overall longitudinal motion request and an overall lateral motion request of the motor vehicle (10); calculate (B104) an overall longitudinal torque request and / or an overall longitudinal speed request, a yaw rate request and a lateral speed request of the motor vehicle (10) using the set of vehicle inputs (CCI);Determine (B106), using a cost optimization function (51), a torque vector to assign the total longitudinal torque requirement and / or the total longitudinal speed requirement, the yaw rate requirement and the side speed requirement to the first drive axis (119F) and the second drive axis (119R) within the calibrated set of constraints, additionally receiving a mode selection signal (MX) from the mode selection device (22M) and adjusting weights within the cost optimization function (51) in response to the mode selection signal (MX); and transmit (B112) a control signal (CL, CCN-CCN) to each of the torque actuators (25, 26, 114E, 14-1, 14-2, 200) to apply the torque vector via the first drive axis (119F) or the second drive axis (119R), respectively;wherein the multiple rotating electric machines (114E) comprise a first electric drive motor (114) coupled to the first drive axle (119F) and a second electric drive motor (14) coupled to the second drive axle (119R); wherein the cost optimization function (51) is further configured to optimize the torque vector for a current tire capacity of the first set of wheels (15F) and the second set of wheels (15R).

Description

INTRODUCTION

[0001] Rotating electric machines are used as torque actuators in a variety of electrified powertrains to generate and absorb torque during charging and discharging. Battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs) typically have an electric drive motor whose output shaft is connected to a drive axle. Some electrified powertrain configurations may employ multiple electric drive motors, either alone or in conjunction with an internal combustion engine. When these various electric drive motors are coupled to their respective drive axles and / or wheels, the resulting configuration is known as an electric all-wheel drive (eAWD) system. SUMMARY

[0002] This paper presents systems, associated control logic, and procedures for controlling the real-time operation of a motor vehicle or other mobile platform with distributed / axle-specific torque actuators, including electric lathes, in an exemplary electric all-wheel drive (eAWD) system. In contrast to powertrain systems where longitudinal torque actuation requirements are analyzed and implemented by a central drive system controller for individual axle drive, such as a single electric drive motor coupled to a rear or front axle, an eAWD drive system has multiple independently actuated drive axles, some of which may include separately actuated half-axles to enable independent four-corner control in a typical vehicle configuration.

[0003] As a result of the development of eAWD drive systems and the associated fast actuator technologies, a new torque allocation strategy and control architecture is required to coordinate the actuation activities of the various electric drive motors located on different drive axles, particularly in a manner that addresses both the longitudinal and lateral control objectives of the vehicle. Within the scope of this disclosure, the capabilities of additional actuators can be controlled, including, but not necessarily limited to, axle-specific or wheel-specific brake actuators, steering actuators, active aerodynamic actuators, and / or roll control actuators, and the like. Overall, such actuators are controlled in accordance with a model-generated torque vector to optimally influence the vehicle / platform dynamics, as described herein.

[0004] The eAWD drive system described here comprises multiple drive axles, each independently coupled to and actuated by a corresponding torque actuator in the form of at least one rotating electric machine. Other representative embodiments also include brake actuators and steering actuators as part of the collective group of torque actuators considered here. Within such a drive system, the electric machines are configured to operate as electric drive / traction motors in a discharge / drive mode, i.e., when an onboard high-voltage battery, fuel cell, or other energy source is discharged at a controlled rate to power the electric machines. These electric machines can also be operated as required in their capacity as electric generators, i.e., in the power generation modes known in the art.

[0005] In particular, the teachings presented here relate to a control-implemented architecture that integrates the objectives of controlling longitudinal torque and lateral motion into a single, multi-axis strategy for optimizing torque distribution. The disclosed strategy, largely executed by a main controller in communication with distributed control units at the local / actuator level, such as motor control processors (MCPs) of the aforementioned electric machines, simultaneously optimizes drive power for the longitudinal and lateral dynamics of the vehicle. Torque allocation is subject to calibrated power limits, including hardware limits, axis interventions, dynamic, thermal, and / or electrical limits, and / or external demand limits, as outlined herein.

[0006] In a representative embodiment, a motor vehicle comprises a first and a second drive axle, each connected to a first and a second set of wheels, and a plurality of torque actuators, including electric lathes, each configured to transmit corresponding output torques to the first and / or second drive axle. The torque actuators considered here may also include, for example, steering actuators, brake actuators, and / or other application-appropriate torque actuators acting on the separate drive axle(s) and / or the wheels connected thereto.

[0007] A master controller is connected to the torque actuators and is programmed with calibrated constraints. The master controller is configured to receive a set of vehicle inputs specifying a total longitudinal motion request and a total lateral motion request for the vehicle, and to calculate, using these vehicle inputs, a total longitudinal torque request and / or a total longitudinal speed request, a yaw rate request, and a lateral speed request for the vehicle.

[0008] The main controller also determines an optimal torque vector and optimal setpoints for other potential actuators using a cost optimization function. The torque vector assigns the total longitudinal torque and / or total longitudinal velocity, yaw rate, and lateral velocity requirements to the first and / or second drive axis, within the calibrated set of constraints. A control signal is then transmitted from the main controller to each of the torque actuators or their associated local control processors to apply the torque vector to the first and / or second drive axis.

[0009] The torque actuators can comprise a first electric machine connected to the first drive shaft and a second electric machine connected to the second drive shaft. In such an embodiment, the first drive shaft and / or the second drive shaft can comprise a corresponding pair of half-shafts. The first electric machine and / or the second electric machine can each comprise a pair of electric machines, each coupled to one of the half-shafts.

[0010] The torque actuators may optionally include one or more brake actuators, each connected to one of the first and second drive axles.

[0011] The above-mentioned limitations may, in an example configuration, include separate hardware limitations, operational limitations and / or external functional limitations.

[0012] In some embodiments, the torque vector is configured to optimize the wheel slip of the first and / or second set of wheels.

[0013] The cost optimization function, executed by the main controller, can be configured to optimize the torque vector for the current tire capacity of the first and / or second set of wheels. The cost optimization function could also be configured to optimize the torque vector for the vehicle's propulsion efficiency or for other outcomes in various embodiments.

[0014] In one possible configuration, the first and second sets of wheels are front and rear wheels, respectively, one or both of which can be steered independently via their respective steering actuators. In such a configuration, the torque actuators could encompass the respective steering actuators.

[0015] An optional operating mode selection device can be configured to receive an operator-requested or autonomously requested operating mode selection signal, with the main controller being configured to change the weights within the cost optimization function in response to the operating mode selection signal.

[0016] In one possible embodiment, the torque actuators can comprise an internal combustion engine configured to generate engine output torque and at least one electronically controlled differential coupled to the internal combustion engine. In such an embodiment, the electronically controlled differential(s) can be configured to receive the engine output torque.

[0017] A method for controlling motion and torque in a motor vehicle with an eAWD drive system, as described above, is also disclosed herein. The method includes receiving the set of vehicle inputs via the main controller, wherein the vehicle inputs specify a total longitudinal motion request and a total lateral motion request of the motor vehicle. The limitations in this representative embodiment include hardware limitations, operational limitations, and / or external functional limitations.

[0018] The procedure includes calculating a total longitudinal torque requirement and / or a total longitudinal speed requirement, a yaw rate requirement, and a lateral speed requirement for the vehicle using the set of vehicle inputs. The procedure also includes determining a torque vector using a cost optimization function to map the total longitudinal torque requirement and / or the total longitudinal speed requirement, the yaw rate requirement, and the lateral speed requirement to the first and second drive axles within the calibrated set of constraints. Furthermore, the procedure includes transmitting a control signal to each of the torque actuators to apply the torque vector via the first and second drive axles, respectively.

[0019] The above-mentioned and other features and advantages of the present disclosure will be readily apparent from the following detailed description of the embodiments and the best ways of carrying out the disclosure when considered in conjunction with the accompanying drawings and the accompanying claims. List of characters Fig. Figure 1 is a schematic representation of an exemplary motor vehicle with an electric all-wheel drive (eAWD) system and a main control unit configured to perform the present procedure. Fig. Figure 2 is a flowchart illustrating an exemplary procedure for assigning torque in the eAWD drive system of Fig. 1 describes. Fig. Figure 3 is a schematic logic flow diagram that shows an example of control logic for use with the motor vehicle of Fig. 1 in the implementation of the present procedure. DETAILED DESCRIPTION

[0020] The present disclosure can be realized in many different forms. Representative examples of the disclosure are shown in the drawings and are described here in detail as non-restrictive examples of the disclosed principles. For this purpose, elements and restrictions described in the sections “Summary”, “Introduction”, “Summary”, and “Detailed Description”, but not expressly set forth in the claims, should not be included in the claims, either individually or collectively, either by implication or by inference or otherwise.

[0021] For the purposes of this description, the use of the singular includes the plural and vice versa, unless expressly excluded; the terms "and" and "or" apply in both the subjunctive and disjunctive moods; "every" and "all" mean "everyone and all"; and the words "including," "containing," "comprehensive," "with," and the like mean "including without limitation." Furthermore, words of approximation such as "about," "almost," "essentially," "generally," "approximately," etc., may be used here to mean "at, close to, or almost at" or "within 0-5% of" or "within acceptable manufacturing tolerances," or logical combinations thereof.

[0022] Referring to the drawings, in which identical reference numbers refer to identical components, shows Fig. Figure 1 schematically shows a representative motor vehicle 10 or other mobile platform with an electric all-wheel drive (eAWD) system configured as described here. The eAWD drive system 11 comprises several rotating electric machines (M E ) 114E, including a rear drive motor 14 and a front drive motor 114 in a simplified embodiment. The primary torque functions of the electric machines 114E are controlled in real time via control signals (arrow CC o) from a main controller (C) 50, i.e., a centralized / monitoring control system, as set out below. Instructions for implementing a torque distribution control strategy according to the present disclosure are embodied in the form of a method 100, an example of which is given in Fig. 2 is shown. Such instructions can be recorded in the memory (M) of the main controller 50 and executed by one or more processors (P) using the associated control logic 50L to achieve the advantages described herein, the memory (M) being programmed with a cost optimization function 51 as detailed below.

[0023] The eAWD drive system 11 can include further powertrain components, such as an optional internal combustion engine (E) 200 with an output shaft 201, which in a possible hybrid-electric configuration provides engine torque (arrow T E ) supplies, as well as a DC-DC converter 18 and an auxiliary battery (B AUX) 160. As is well known in the field, high-voltage drives can operate at voltages of 300 V or more, while the low-voltage / auxiliary functions on board typically operate at 12–15 V. Therefore, the terms “low voltage” and “auxiliary voltage,” as used here, refer to nominal 12 V voltage levels, while “high voltage” refers to voltage levels far exceeding the auxiliary voltage levels. The DC-DC converter 18 is thus able, through internal switching operations and signal filtering, to receive a relatively high DC voltage from a DC bus and output the auxiliary voltage to the auxiliary battery 160.

[0024] The representative motor vehicle 10 of Fig. 1 comprises front wheels 15F mounted on a front drive axle 119F and rear wheels 15R mounted on a rear drive axle 119R. Depending on the configuration, electronically controlled differentials 30 and / or 130 can be used to manage the optional engine torque (arrow T). E ) and / or the output torque (arrows T) o ) to distribute from the electric machines 114E to the front and / or rear wheels 15F and / or 15R of the motor vehicle 10 in different drive modes.

[0025] In some embodiments, the front and rear drive axles 119F and 119R can be configured as follows: the front drive axle 119F can be configured as half-axles 119F-1 and 119F-2, and the rear drive axle 119R can also be configured as half-axles 119R-1 and 119R-2. In such an embodiment, the half-axles 119F-1 and 119F-2 can be connected to the electronically controlled differential 130. The half-axles 119R-1 and 119R-2 could be connected to the electronically controlled differential 30, with this configuration enabling independent torque distribution to the front wheels 15F and / or the rear wheels 15R within the scope of method 100. The present strategy can be extended in various embodiments to configurations: (1) one that uses a single drive source, e.g.(1) the electric machine 114E, which is connected to an electronically limited slip differential (eLSD), which would allow a variation of torque between the left and right sides of a given drive axle, and (2) separate electric machines 114E, each directly connected to one of the impellers 15R or 15F, i.e., without a mechanical connection between the left and right sides. Option (2) therefore eliminates the use of the aforementioned differentials 30 and 130.

[0026] For the sake of clarity and simplicity, shown schematically, in some embodiments the front wheels 15F and the rear wheels 15R can be steered independently of each other via a corresponding steering actuator 26. Likewise, the front wheels 15F and the rear wheels 15R can be braked independently of each other via a corresponding brake actuator 26. Such brake actuators 26 could be controlled independently of each other and connected to a specific wheel 15F or 15R or a half-shaft 119F-1, 119F-2, 119R-1, 119R-2, or a single brake actuator 26 could stop the rotation of the wheels 15F or 15R coupled to a specific drive shaft 119F or 119R, e.g., as an electronic brake actuator.Thus, in applications where the torque of drive actuators such as the electric machines 114E is not available on individual axes, a certain degree of torque control via the brake actuators 26 is still possible.

[0027] The steering actuators 25 and the brake actuators 26 respond to the pressure or actuation of an accelerator pedal 22A and a brake pedal 22B, thereby generating a corresponding accelerator pedal request signal (arrow Ax) and a brake pedal request signal (arrow Bx). A driver of the motor vehicle 10 can use a steering wheel 22S to control a steering angle (arrow θ). x ) influence the main control 50 as part of a set of input signals (arrow CC) I) is read together with the accelerator pedal request signal (arrow Ax) and the brake request signal (arrow Bx). The main control unit 50 can also receive an operating mode selection signal (arrow Mx) from an optional operating mode selection device (MSD) 22M as part of the input signals (arrow CC). I ) received, the operation of the operating mode selection device 22M is described in more detail below.

[0028] Still referring to Fig. Figure 1 shows the eAWD drive system 11 in an embodiment in which the front drive motor 114 is connected to the front drive axle 119F via an output element 117, e.g., a drive shaft and a possible gearbox. The front drive motor 114 can be configured as an AC device in which a wound stator 114S receives a single-phase or multi-phase electrical current from an onboard DC power supply located in Fig. 1 as a representative high-voltage battery pack (B HV Figure 16, e.g., a multi-cell lithium-ion battery, is shown. In such an embodiment, the battery pack 16 is connected to the wound stator 114S via a traction inverter module (TPIM-2) 20-2, wherein a corresponding motor control processor (MCP-2) locally controls the output torque and speed of the front drive motor 114 as a function of the output signals (arrow CC o). Once energized, the wound stator 114S generates a rotating electromagnetic field that interacts with a field of a magnetic rotor 114R, which can be circumscribed by the wound stator 114S in a typical rotating flux configuration.

[0029] The eAWD drive system 11 can use a similar setup for driving the rear impellers 15R. For example, the rear drive motor 14 can comprise a rotor 14R surrounded by a wound stator 14S, with the rear drive motor 14 being excited via a corresponding TPIM-1 20-1 with a resident / local motor control processor, i.e., MCP-1. The rear drive motor 14 could, as shown, be coupled to the differential 30 via an output element 17, with the output element 17 transmitting its own output torque (arrow To) to the rear impellers 15R.

[0030] In a possible alternative configuration, independent torque control for each of the rear wheels 15R can be provided by arranging separate rear drive motors 14-1 and 14-2 on the respective half-axles 119R-1 and 119R-2. In such an embodiment, the rear drive motors 14-1 and 14-2 can be individually connected to a corresponding TPIM 20-IA and 20-1B (TPIM-1A and TPIM-1B, respectively), instead of using a single TPIM 20-1 for a single rear drive motor 14. Although omitted for clarity, a person skilled in the art will understand that the single front drive motor 114 can similarly be replaced by separate electric drive motors coupled to each of the half-axles 119F-1 and 119F-2 to independently drive the front wheels 15F on opposite sides of the motor vehicle 10.

[0031] The term "controller," as used here for simplicity, can include one or more electronic control modules, units, processors, and associated hardware components, such as application-specific integrated circuits (ASICs), systems-on-chip (SoCs), electronic circuits, and other hardware required to provide the programmed functionality. In a representative three-motor configuration, as described in one embodiment in Fig. As shown in Figure 1, the main control unit 50 could be a motor control unit for a drive axle with a single drive unit, e.g. the front drive axle 119F in an embodiment in which the electric drive motor 114 is Fig. 1 is used. Such an arrangement can help ensure a balanced CAN communication delay between the main controller 50 and the various secondary control units communicating with it, e.g., MCP-1, MCP-1A, MCP-1B, and MCP-2, as well as the local control units for the brake actuators 26 and the steering actuators 25. Axle-based control functions could then be assigned to such local control units to enable faster local, feedback-based control of the individual drive axles 119F, 119R, 119F-1, 119F-2, 119R-1, and / or 119R-2, so that wheel slip and other rapid dynamics can be controlled in real time or preventively.

[0032] The main control 50 of Fig. 1, whose representative tax logic 50L in Fig. 3, can be implemented as one or more electronic control units or computing nodes that respond to the input signals (arrow CC). I) react. The main controller 50 comprises application-specific amounts of memory (M) and one or more processors (P), e.g., microprocessors or central processing units, as well as other associated hardware and software, e.g., a digital clock or timer, input / output circuits, buffer circuits, etc. The memory (M) may contain sufficient amounts of read-only memory, e.g., magnetic or optical memory.

[0033] Fig. 2 and Fig. Figure 3 shows the method 100 according to an exemplary embodiment and a corresponding control logic 50L for implementing the method 100 on board the motor vehicle 10. The method 100 of Fig. Section 2 serves to integrate lateral vehicle dynamics objectives into a torque control architecture that is proactively executed by the main controller 50. Within the framework of this strategy, lateral motion objectives such as the desired yaw rate and lateral velocity are used as optimization targets. This is done in addition to the traditional longitudinal objectives, which are typically determined based on the driver's requirements for overall torque and speed.

[0034] In particular, the execution of method 100 includes a multi-criteria optimization / settling to determine an optimal torque distribution over several axes, such as the representative drive axes 119F and 119R of Fig. 1 or its half-axis variants. Axis-based arbitration is then used after optimization to provide additional flexibility to enforce external axis-based interventions or other performance limits required to protect the underlying hardware, operational limits, stability, or other dynamic limits, etc.

[0035] Referring to Fig. 2. The main control unit 50 communicates with local control units of a variety of torque actuators, including the electric machines 114E described above and possibly including the brake actuators 26 and / or the steering actuators 25, the electronically controlled differentials 30 and 130, etc. The main control unit 50 is located in block B102 of Fig. 2, which was previously programmed with a calibrated set of restrictions, is configured to accept the set of vehicle inputs (arrow CC). I from Fig. 1) receives a total longitudinal motion request of the motor vehicle 10, for example a total requested torque (T REQ ) and / or an overall speed requirement (N REQ ) of the motor vehicle 10, together with a lateral movement request (MOT) LAT ) of the motor vehicle 10.

[0036] In a typical deployment scenario, a driver of the motor vehicle can 10 in Fig. 1 for example the requirement of the total torque (T REQ ) and the total speed (N REQ ) generated by acceleration and braking requests, e.g. by actuating the accelerator pedal 22A and the brake pedal 22B. The request for lateral movement (MOT) LAT ) can be partially achieved using the steering angle (arrow θ) X ) from Fig. 1 can be determined. In autonomous embodiments, such vehicle inputs (arrow CC) can be I in Fig. 1) are automatically generated by the main control unit 50 and / or another dedicated control unit. Procedure 100 then proceeds to block B104.

[0037] In block B104, the main control unit 50 calculates separate total requirements for lateral and longitudinal torque or motion (T) using the set of vehicle inputs from block B102. LAT or T LONG As part of block B104, the main control unit 50 can calculate a yaw rate request and a lateral speed request for the vehicle 10, again using the steering angle (arrow 0 x) as the relevant input. The procedure 100 then continues with block B106.

[0038] Block B105 of Fig. In this embodiment, 2 includes the estimation of the current state of the motor vehicle 10 (EST ST). 10As is known from the prior art, state estimation is typically used in vehicle applications to determine, for example, the current speed, attitude (pitch, yaw, and roll), the current states of various drives (e.g., the electric machines 114E, the motor 200, etc.), the state of charge, temperature, voltage, current, and / or other relevant electrical parameters, in this case, the battery pack 16. Fig. 1. to monitor. The condition assessment can also take into account the tire pressure and tire capacity, the current or impending wheel slip of one or more of the wheels 15R and 15F, etc. Based on trajectories of such values, the main controller 50 can predict the condition of the motor vehicle 10 at a future time. The current condition of the motor vehicle 10 is therefore fed into the cost optimization function 51 of Fig. 1 is fed in so that the main control 50 knows the current state before it begins with the optimization calculations specific to the procedure 100.

[0039] Block B106 of procedure 100 includes the determination of a torque vector via the main control 50 using the cost optimization function (ƒ OPT ) 51 of Fig. 1 a torque vector T→ for assigning the total longitudinal torque requirement and / or the total longitudinal speed requirement, the yaw rate requirement, and the side speed requirement to the front drive axle 119F and / or the rear drive axle 119R within the aforementioned calibrated set of constraints. As used herein and in the prior art, a torque vector for a simplified three-motor / dual axle may, for example, have the following form T→−[A,B,C], where A, B and C are the torques assigned to the different drive axles A, B and C.

[0040] As is well known in the field, numerous cost-function-based optimization strategies exist that employ dynamic models in the form of mathematical equations to optimize a specific outcome while considering competing values ​​and constraints. The dynamic model used for optimization, for example, provides the dynamic relationship between the manipulated actuators, such as torque distribution, friction braking torques, rear-axle steering, etc., and the vehicle's dynamic states, such as longitudinal speed / acceleration, lateral speed / acceleration, yaw rate, wheel speeds, etc. The optimization performed here can use such a dynamic model to predict an expected vehicle response based on actuator setpoints and then select suitable actuator setpoints that optimize the overall cost function 51 for the predicted trajectories.To implement the cost optimization function 51 used here, the main controller 50 can, for example, be programmed with relevant tracking functions, e.g. for the desired longitudinal speed, the requirement of the longitudinal torque, the desired yaw rate, etc., taking into account the restrictions mentioned above.

[0041] Constraints can be either soft or hard, depending on whether the constraint can be occasionally violated (soft) or not (hard). The optimization simultaneously considers all costs within the cost function 51 and finds optimal actuator setpoints, e.g., a suitable torque vector that minimizes costs and provides an optimal trade-off between objectives. Penalties can be applied in real time by overweighting certain factors such as energy consumption or stability, e.g., by adjusting the numerical weights in the mathematical equations.

[0042] Exemplary constraints that could be considered by the main controller 50 include, among others, pursuing the most efficient possible torque distribution between the drive axles 119F and 119R and / or the various wheels 15F and 15R, limiting wheel slip to a specific slip ratio, limiting each assigned axle torque to a corresponding estimated tire capacity, limiting longitudinal speed to control overspeed, or limiting total torque to enforce external total torque limits. Since such considerations can be mathematically modeled in various forms, the optimization within the scope of the disclosure, and thus the optimal solution for a given set of dynamic modeling equations in a non-restrictive embodiment, could involve searching for the lowest-cost solution.

[0043] As part of block B106, the main control 50 could receive the operating mode selection signal (arrow Mx ​​in). Fig. 1) received by the mode selection device 22M, regardless of whether it was requested by the operator or autonomously. The main controller 50 could then change the weighting within the aforementioned cost optimization functions in response to the mode selection signal. For example, if a driver selects "Sport Mode," lateral performance objectives, such as maintaining a driver-desired yaw rate, can be prioritized over factors such as powertrain efficiency, with certain combinations of torque actuation being penalized or favored by unitless weights to achieve the performance expected by the specified mode.

[0044] The torque vector could also be similarly optimized in block B106 for the wheel slip of the front and / or rear wheels 15F and / or 15R, for example, by penalizing distributions that would cause wheel slip or worsen existing wheel slip conditions on one or more of the wheels 15F and / or 15R. For instance, to simultaneously prevent a slip ratio threshold from being exceeded on one of the wheels 15F or 15R while still meeting the rider's overall torque demand, optimization function 51 automatically shifts the torque distribution to allocate more torque to the wheels 15F or 15R with less slip and less torque to the wheels 15F or 15R exceeding the slip ratio.

[0045] Similarly, block B106 could involve optimizing the torque vector for the current tire capacity of the front and / or rear wheels 15F and / or 15R, thereby preventing slip conditions. In this case, based on the current tire capacity and the vehicle dynamics model used by the optimization function 51, the optimization function 51 would predict that some potential torque distributions would result in unacceptable wheel slip on some of the wheels 15F or 15R, negatively impacting the ability of the vehicle 10 to meet the driver's longitudinal torque or speed requirements. Consequently, the optimization would automatically avoid such potential distributions as a cost function minimization and instead find other distributions that better meet the driver's longitudinal torque or speed requirements.This means that the distribution of torque to the different axles could be optimized with regard to wheel slip, with possible control measures including a preventive distribution of torque based on knowledge of the tire capacity on the individual wheels, as well as a reactive distribution if excessive slip is actually detected on one of the wheels.

[0046] The main control unit 50 could also optimize the torque vector. T→ with regard to the propulsion efficiency of the motor vehicle 10, i.e., by returning solutions that favor energy efficiency over other factors such as speed or cornering behavior. The latter optimization could disadvantage a torque allocation that reduces the electrical efficiency of the battery pack 16. Fig. 1 would decrease, or would increase the electrical energy or fuel consumption in embodiments in which the eAWD drive system 11 includes the motor 200.

[0047] There are conceivable examples where efficiency considerations are linked to one or more other goals, involving compromises or sacrifices as described above. For example, one could consider a scenario in which the motor vehicle accounts for 10 of Fig. 1. The vehicle is driving straight ahead on a road. In this case, the vehicle 10 would follow the most efficient torque distribution, as such a distribution is also optimal for the longitudinal and lateral reactions desired by the driver. Alternatively, the same driver could attempt an aggressive cornering maneuver. In such a case, the most efficient torque distribution might not correspond to the driver's desired longitudinal and lateral reactions. Consequently, the optimization function 51 and the associated control strategy would compromise between efficiency and lateral requirements based on their respective weightings.

[0048] After performing such an optimization in block B106 of Fig. 2 The procedure 100 transfers to block B108, with the main controller 50 determining external limits or axis interventions. Such limits could be communicated to the main controller 50 by another control unit, e.g., an electronic stability control or traction control module, or such limits could originate from various functions within the main controller 50. The limits could include calibrated hardware limits designed to protect the structural integrity of the various components of the eAWD drive system 11, such as associated thermal, torque, acceleration, or other suitable thresholds, as well as dynamic limits that take into account stability, traction, or other performance constraints.

[0049] The limit values ​​considered in block B108 are then applied together in block B109 (LIM) to adjust the torque vector output of block B108 as needed to accommodate the limit values. Procedure 100 then proceeds to block B110.

[0050] Block B110 includes the execution of an axis-based arbitration (ARB T). AXL ) via the main controller 50. As a possible implementation of block B110, such arbitration could involve the main controller 50 determining whether to follow an optimal torque request generated in block B106 or the request of the external function and the limit values ​​applied in blocks B108 and B109. Weighting an external request function ensures that the main controller 50 selects the request of the external function under suitable conditions, e.g., during a high-slip event in traction control.

[0051] The torque vector T→ The torque demand generated by the optimization in block B106 is therefore not sent to the various torque actuators in this case, but rather a request from an external requester, such as an anti-lock braking system (ABS). Under operating conditions where the external requester has a low priority, such as under normal driving conditions, the reverse decision is made by block B110, applying the optimal torque demand generated in block B106 via the torque vector. The process then proceeds to block B112.

[0052] In block B112 of Fig. 2 The main control unit 50 transmits a control signal (CL → T). ACT ) to each of the torque actuators, i.e. to the electric machines 114E, the brake actuators 26, the steering actuators 25, the differentials 30 and 130, etc., in order to thereby determine the torque vector T→ via the front drive axle 119F and / or the second drive axle 119R. The individual torque actuators and the associated local control units respond to these instructions with a corresponding output, be it brake pressure, steering response or engine torque, depending on the type of actuator.

[0053] With reference to Fig. 3 A representative control logic 50L for implementing the method 100 described above and alternative embodiments is shown within the scope of the disclosure. For example, the cost optimization function 51 described above can be implemented as an optimization logic block (OPT) 51B, including (a) optimization goals 510 and (b) optimization constraints 51C. Such an optimization block 51B knows the assignments from a previous time step to determine the optimal torque distribution in a subsequent time step; that is, the optimization logic block 51B is iterative.

[0054] The optimization objectives 51O correspond to the optimization of axle torque requirements to meet defined tracking objective functions, as mentioned above, with calibratable weighting to balance priorities between such objectives. The optimization constraints 51C also limit the optimization results, for example, by enforcing a calibrated maximum torque equal to the sum of the individual axle torques, or by restricting the vehicle speed to a speed target, or by ensuring that the axle torque requirements comply with drive system constraints, such as battery power limits, wheel slip ratio, etc.

[0055] Logic block 51B, which is connected to the various in Fig. The optimization logic block 51B communicates with the input devices shown in Figure 1, namely the accelerator pedal 22A, the brake pedal 22B, and the steering wheel 22S. In response to the driver actuating the pedals 22A and / or 22B or turning the steering wheel 22S, the optimization logic block 51B receives the torque request (arrow T). REQ ), the speed requirement (arrow N) REQ ), the lateral velocity (V LAT ), the requested yaw rate (ψ REQ ) as well as the arbitrary torque (arrow T) ARB ) and the arbitrary velocity (N ARB ) from block B110 of Fig. 2. Similarly, logic block 51B receives the estimated state of motor vehicle 10 from a state estimation block 54, which is part of block B105. Fig. 2 corresponds to, and external torque and speed limits from an external limit block 55, which corresponds to blocks B108 and B109 of Fig. This corresponds to point 2. Therefore, external requesters have priority in determining axle torque requirements, which are decided upon after the axle torque requirements have been optimized. A possible implementation in the optimization scheme thus involves imposing the external requester with the highest priority or weight as an additional hard constraint on the affected axle(s).

[0056] The outputs of logic block 51B in Fig. 3 include initial axle torque commands (T AXL1 , ..., T AXLN ) for N drive axles, with N = 2 in a simplified two-axle embodiment, up to N = 4 in an embodiment of Fig. 1, in which independent control of the four corners of the motor vehicle 10 with four different drive axles is used. The arbitration blocks 56-1, ..., 56-N are used to control block B110 of Fig. 2 to implement and to define the initial axle torque commands (T AXL1 ,..., T AXLN ) with regard to external axle torque limits (EXT T AXL LIM) from the external request block 58. Afterwards, the main controller 50 transmits control signals to the individual torque actuators according to block B112 of Fig. 2, where the arrows CC1,..., CC N such control signals in Fig. Show 3.

[0057] The present strategy could also be applied in cases where the output of the local control units, e.g. MCP-1, MCP-2, MCP-1A or MCP-1B, is controlled by Fig. 1, also a command and / or a modification for the steering actuators 25. In this case, a specific local control unit could be programmed to provide a yaw rate based on the steering angle command and torque vectoring via the electric machines 114E and / or the brake actuator(s) 26.

[0058] As should be clear to those skilled in the art from the foregoing, the present strategy makes it possible to control the sum of the individual axle torques in a closed control loop in such a way as to track a total torque or speed request from the driver in different operating modes. The relative weighting of the associated costs or penalties is used to select a priority between different control objectives, with these costs potentially being adjusted using calibratable or selectable weights based on the driving conditions or operating mode. Within these possibilities, the torque allocations remain subject to the limitations of the drive system, such as axle torque limits, motor limits and half-shaft limits, battery power limits, and the like.The present teaching thus enables a new architecture for coordinating the operation of various torque actuators arranged on different drive axles in order to achieve both the longitudinal and lateral control objectives of the vehicle. These and other advantages will be readily apparent to those skilled in the art in light of the preceding disclosure.

[0059] The detailed description and the drawings or figures are supporting and descriptive of the present teaching, but the scope of the present teaching is defined exclusively by the claims. While some of the best modes and other embodiments for carrying out the present teaching have been described in detail, there are various alternative designs and embodiments for carrying out the present teaching, which are defined in the appended claims. Furthermore, this disclosure expressly includes combinations and subcombinations of the elements and features shown above and below.

Claims

[1] A motor vehicle comprising: a first drive axle connected to a first set of wheels; a second drive axle connected to a second set of wheels; a plurality of torque actuators, each connected to the first drive axis or the second drive axis and configured to transmit corresponding output torques to the first drive axis and / or the second drive axis, wherein the plurality of torque actuators comprises several rotating electrical machines; and a main controller that interacts with the multitude of torque actuators, the main controller being programmed with a calibrated set of constraints and configured to: Receiving a set of vehicle inputs specifying an overall longitudinal movement request and an overall lateral movement request for the motor vehicle; Calculate a total longitudinal torque requirement and / or a total longitudinal speed requirement, a yaw rate requirement and a lateral speed requirement of the motor vehicle using the set of vehicle inputs; Determine, using a cost optimization function, a torque vector to assign the total longitudinal torque requirement and / or the total longitudinal speed requirement, the yaw rate requirement and the transverse speed requirement to the first drive axis and the second drive axis within the calibrated set of constraints; and Transmitting a control signal to each of the torque actuators in order to apply the torque vector via the first drive axis or the second drive axis. [2] Motor vehicle according to claim 1, wherein the multiple rotating electric machines comprise a first electric drive motor coupled to the first drive axle and a second electric drive motor coupled to the second drive axle. [3] Motor vehicle according to claim 2, wherein the first drive axle and / or the second drive axle comprises a respective pair of half-axles, and wherein the first electric drive motor and / or the second electric drive motor comprises a respective pair of electric drive motors, each coupled to one of the half-axles. [4] Motor vehicle according to claim 1, wherein the plurality of torque actuators comprises one or more brake actuators, each of which is connected to the first drive axle or the second drive axle. [5] Motor vehicle according to claim 1, wherein the set of restrictions includes hardware restrictions, operational restrictions and / or external functional restrictions. [6] Motor vehicle according to claim 1, wherein the torque vector is configured to optimize the wheel slip of the first set of running wheels and / or the second set of running wheels. [7] Motor vehicle according to claim 1, wherein the cost optimization function is configured to optimize the torque vector for the current tire capacity of the first set of wheels and the second set of wheels. [8] Motor vehicle according to claim 1, wherein the cost optimization function is configured to optimize the torque vector for the drive efficiency of the motor vehicle. [9] Motor vehicle according to claim 1, wherein the first set of wheels and the second set of wheels are front and rear wheels respectively, the first set of wheels and / or the second set of wheels are steerable via respective steering actuators and the plurality of torque actuators comprises the respective steering actuators. [10] Motor vehicle according to claim 1, wherein the multiple torque actuators comprise an internal combustion engine configured to generate an engine output torque including the output torques, and an electronically controlled differential coupled to the internal combustion engine, wherein the electronically controlled differential is configured to receive the engine output torque from it.