Vehicle control method and readable storage medium

Abstract

The application relates to a vehicle control method and a readable storage medium. When a vehicle line control front turning system fails, a front wheel turning angle total compensation target is determined based on a steering wheel turning angle and a front wheel turning angle fault position, a rear wheel turning angle compensation target in the front wheel turning angle total compensation target is distributed to a rear wheel turning system to obtain a rear wheel turning angle instruction, the remaining turning angle compensation target is distributed to a distributed drive torque vector system based on physical constraints of the distributed drive torque vector system to determine an additional yaw moment instruction, and steering is controlled based on the rear wheel turning angle instruction and the additional yaw moment instruction. Compared with traditional single system control backup steering, the application fuses the rear wheel turning system and the distributed drive torque vector system when the vehicle line control front turning system fails, equivalently corrects front wheel turning angle abnormal deviation at the vehicle level, realizes backup steering, maximizes the steering performance of the vehicle before the abnormality in the fault state, and improves the control safety of the vehicle.

Description

Technical Field

[0001] This application relates to the field of vehicle safety technology, and in particular to a vehicle control method, device, electronic device, computer-readable storage medium, and computer program product. Background Technology

[0002] With the development of vehicle technology, steer-by-wire (SBW) eliminates the traditional mechanical connection between the steering wheel and the steering actuator, freeing the actuator from mechanical constraints and granting greater freedom to active control. However, steer-by-wire relies entirely on electronic signals and network communication, and the risk of malfunction is the biggest constraint to its mass production. Besides maximizing the reliability of the steer-by-wire control system itself, with the widespread application of various intelligent devices in new chassis, redundant backup steering is another effective way to proactively address steer-by-wire control failures. Currently, redundant backup steering for steer-by-wire failures primarily considers providing minimum performance to bring the vehicle to the side as quickly as possible.

[0003] However, when steer-by-wire fails, road conditions may not allow for immediate pulling over. Backup steering designed to provide minimum performance results in a significantly different driving state compared to other vehicles, thus reducing driving safety. Therefore, current methods for controlling steer-by-wire failure have inherent safety drawbacks. Summary of the Invention

[0004] Therefore, it is necessary to provide a vehicle control method, device, electronic device, computer-readable storage medium, and computer program product that can improve safety in response to the above-mentioned technical problems.

[0005] In a first aspect, this application provides a vehicle control method, including:

[0006] When the vehicle's steer-by-wire system malfunctions, the fusion backup steering function is activated, and the total compensation target for the front wheel angle is determined based on the real-time acquisition of the steering wheel angle and the fault location of the front wheel angle.

[0007] Based on the physical constraints of the vehicle's rear wheel steering system, the rear wheel steering angle compensation target in the total front wheel steering angle compensation target is determined, and the rear wheel steering angle compensation target is assigned to the vehicle's rear wheel steering system to obtain the rear wheel steering angle command;

[0008] Based on the physical constraints of the vehicle's distributed drive torque vector system and the remaining steering angle compensation target, an additional yaw moment command is determined; the remaining steering angle compensation target represents the remaining steering angle compensation target of the total front wheel steering angle compensation target after allocating the rear wheel steering angle compensation target;

[0009] The vehicle steering is controlled according to the rear wheel steering angle command and the additional yaw moment command.

[0010] Secondly, this application also provides a vehicle control device, comprising:

[0011] The acquisition module is used to activate the fusion backup steering function when the vehicle's steer-by-wire system fails. It determines the total compensation target for the front wheel angle based on the real-time acquired steering wheel angle and the fault location of the front wheel angle.

[0012] The first calculation module is used to determine the rear wheel angle compensation target in the total front wheel angle compensation target based on the physical constraints of the rear wheel steering system of the vehicle, and to allocate the rear wheel angle compensation target to the rear wheel steering system of the vehicle to obtain the rear wheel angle command.

[0013] The second calculation module is used to determine the additional yaw moment command based on the physical constraints of the vehicle's distributed drive torque vector system and the remaining steering angle compensation target; the remaining steering angle compensation target represents the remaining steering angle compensation target of the total front wheel steering angle compensation target after allocating the rear wheel steering angle compensation target;

[0014] The control module controls the vehicle steering according to the rear wheel steering angle command and the additional yaw moment command.

[0015] Thirdly, this application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method.

[0016] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0017] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method.

[0018] The aforementioned vehicle control method, device, electronic equipment, computer-readable storage medium, and computer program product, when the vehicle's steer-by-wire system malfunctions, determine the total front wheel angle compensation target based on the steering wheel angle and the location of the front wheel angle fault. Based on the physical constraints of the rear wheel steering system, the rear wheel angle compensation target from the total front wheel angle compensation target is allocated to the rear wheel steering system to obtain the rear wheel angle command. Based on the physical constraints of the distributed drive torque vector system, the remaining angle compensation targets are allocated to the distributed drive torque vector system to determine the additional yaw moment command. Based on the rear wheel angle command and the additional yaw moment command, the vehicle steering is controlled. Compared to traditional single-system control backup steering, this application, by integrating the control of the rear wheel steering system and the distributed drive torque vector system when the vehicle's steer-by-wire system malfunctions, effectively corrects the abnormal deviation of the front wheel angle at the vehicle level, achieving backup steering. This allows the vehicle to maintain its steering performance before the abnormality to the maximum extent under the aforementioned fault state, improving the vehicle's control safety. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating a vehicle control method in one embodiment;

[0021] Figure 2 This is a schematic diagram comparing the normalized step response of different control channels to yaw rate in one embodiment.

[0022] Figure 3 This is a schematic diagram comparing the normalized step response of different control channels to yaw rate in another embodiment.

[0023] Figure 4 This is a schematic diagram comparing the normalized step response of different control channels to yaw rate in another embodiment.

[0024] Figure 5 This is a schematic diagram comparing the normalized step response of different control channels to lateral acceleration in one embodiment;

[0025] Figure 6 This is a schematic diagram comparing the normalized step responses of different control channels to lateral acceleration in another embodiment;

[0026] Figure 7This is a schematic diagram comparing the normalized step response of different control channels to lateral acceleration in another embodiment;

[0027] Figure 8 This is a schematic diagram illustrating the negative modulation of the rear wheel steering angle to lateral acceleration step response using a low-pass filter in one embodiment.

[0028] Figure 9 This is a schematic diagram illustrating the negative modulation of the rear wheel steering angle to lateral acceleration step response through a low-pass filter in another embodiment.

[0029] Figure 10 This is a schematic diagram illustrating the improvement of the negative modulation of the rear wheel steering angle to lateral acceleration step response using a low-pass filter in yet another embodiment;

[0030] Figure 11 This is a flowchart illustrating the vehicle control method in another embodiment;

[0031] Figure 12 This is a schematic diagram illustrating the yaw rate performance gains of a step-steering vehicle in one embodiment.

[0032] Figure 13 This is a schematic diagram illustrating the lateral acceleration performance gains of a step-steering vehicle in one embodiment;

[0033] Figure 14 This is a schematic diagram of a step steering rear wheel angle control command in one embodiment;

[0034] Figure 15 This is a schematic diagram of a step steering additional yaw moment control command in one embodiment;

[0035] Figure 16 This is a structural block diagram of a vehicle control device in one embodiment;

[0036] Figure 17 This is a diagram of the internal structure of an electronic device in one embodiment. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0039] In related technologies, the implementation of backup steering is mainly limited to single-system control, such as Active-Rear-Steer (ARS) or Torque-Vectoring (TV). It is well known that ARS and TV are typically used only as auxiliary systems for forward steering. If steering is accomplished independently using only a single system, both have limitations in performance. Multi-system fusion control can leverage the strengths and mitigate the weaknesses of different systems to maximize overall performance, but it is still in its early stages in the industry. In past mass-produced vehicles, models simultaneously equipped with SBW, ARS, and 3 / 4 motor TV configurations are still rare. Furthermore, the traditional system architecture has low integration between the power domain and chassis domain, and cross-system calibration is difficult without the support of positive dynamics design. Many academic studies on fusion control tend to abstract practical fusion control problems into ideal mathematical optimization, but these methods generally have significant engineering limitations and insufficient practical value.

[0040] To address the shortcomings of current technologies, this application proposes a novel fusion control approach based on a rear-wheel steering (ARS) system and a distributed drive TV system to improve backup steering performance and enhance vehicle control safety. This solution incorporates thorough theoretical justification based on vehicle dynamics and demonstrates both feasibility and reliability for engineering deployment.

[0041] In one embodiment, such as Figure 1 As shown, a vehicle control method is provided. This embodiment illustrates the application of this method to a vehicle control unit. It is understood that this method can also be applied to a server, or to a system including a vehicle control unit and a server, and implemented through the interaction between the vehicle control unit and the server. The vehicle can be a four-wheeled vehicle, which may include a vehicle control unit for controlling various devices and functions within the vehicle. The vehicle may also have steer-by-wire (SBW) front wheel steering, active rear wheel steering (ARS), and distributed torque vectoring (TV) functions. The control trigger condition can be a malfunction in the vehicle's steer-by-wire front wheel steering, for example, the front wheel angle failing to follow the steering wheel movement to the correct position. When the vehicle control unit detects the trigger condition, it determines that redundant backup steering functions need to be invoked to restore the vehicle's steering function.

[0042] This embodiment includes the following steps S202 to S208. Wherein:

[0043] In step S202, when the vehicle's steer-by-wire system malfunctions, the fusion backup steering function is activated, and the total compensation target for the front wheel angle is determined based on the real-time obtained steering wheel angle and front wheel angle fault location.

[0044] Specifically, the vehicle control unit determines a fault in the vehicle's steer-by-wire system, activates the fusion backup steering function, acquires the steering wheel angle in real time to determine the driving intention, and, based on the driving intention and the location of the front wheel angle fault, determines the total front wheel angle compensation target. The total front wheel angle compensation target represents the required rotation angle of the vehicle's front wheels.

[0045] To determine the true steering intention, the vehicle control unit can acquire the vehicle's steering wheel angle δ in real time. hand During normal driving, the steering wheel angle δ hand Mapped to front wheel steering angle command δ f cmd When the steer-by-wire malfunctions, the actual front wheel steering angle may lock at an abnormal position δ. f lock Therefore, the total compensation target for the front wheel steering angle is δ. f total The difference between the two should be: δ f total =δ f cmd -δ f lock .

[0046] Step S204: Based on the physical constraints of the rear wheel steering system of the vehicle, determine the rear wheel angle compensation target in the total front wheel angle compensation target, assign the rear wheel angle compensation target to the rear wheel steering system of the vehicle, and obtain the rear wheel angle command.

[0047] The vehicle control unit can determine the basic allocation strategy among multiple systems based on vehicle dynamics principles. The aforementioned integrated backup steering function has a corresponding allocation strategy. Following this strategy, and based on the physical constraints of the vehicle's rear-wheel steering system, the vehicle control unit first determines the rear-wheel angle compensation target from the overall front-wheel angle compensation target, and then allocates the rear-wheel angle compensation target to the rear-wheel steering system to determine the rear-wheel angle command. That is, the rear-wheel angle compensation target represents the steering target completed by the rear-wheel steering system. The aforementioned physical constraints of the rear-wheel steering system include the vehicle's rear-wheel mechanical angle constraints and mechanical thrust constraints. The vehicle control unit then allocates the remaining angle compensation targets to the distributed drive torque vector system, and, in conjunction with the physical constraints of the distributed drive torque vector system, determines the additional yaw moment command.

[0048] During backup steering, both Active Rear-wheel Steering (ARS) and Distributed Torque Vectoring (TV) can effectively compensate for abnormal front wheel steering angles. The allocation strategy between the ARS and TV systems can be formulated based on vehicle dynamics principles. Specifically, the theoretical analysis mainly focuses on the front wheel steering angle δ. f Rear wheel steering angle δr, additional yaw moment M z The three control channels respectively control vehicle attitude (yaw rate γ) and vehicle tracking performance (lateral acceleration a). y The impact of ).

[0049] Backup steering is primarily used for steering needs within the tire's linear zone, and qualitative and quantitative analyses can be conducted using a vehicle linear two-degree-of-freedom model.

[0050] Specifically, the equilibrium equations for the lateral forces and the moment equilibrium equations for the vehicle can be expressed as follows:

[0051] ma y =mv(γ+β')=F yf +F yr ;I z γ'=F yf l f -F yr l r +M z .

[0052] Based on the linearity assumption of the tire, the relationship between the tire lateral force and the slip angle is as follows:

[0053] F yf =C f *(δ f -β-(l f / v)γ), F yr =C r *(δ r -β+(l r / v)γ).

[0054] In the formula, m is the vehicle mass; a y Ma represents the lateral acceleration of the entire vehicle. y The total lateral force required to generate lateral acceleration; I z C is the moment of inertia of the vehicle during yaw. f and C r These are the equivalent lateral stiffness of the front and rear axles, respectively; F yf and F yr These represent the lateral forces on the front and rear axles, respectively; l f and l r These are the distances from the front and rear axles to the center of mass, respectively; l = l f +l rδ is the front and rear wheelbase; v is the vehicle speed; γ is the yaw rate, γ' is the yaw acceleration; β is the vehicle sideslip angle, β' is the vehicle sideslip rate; δ f and δ r These are the front wheel steering angle and the rear wheel steering angle, respectively; M z The additional yaw moment generated by the distributed drive torque vectoring system; F yf F represents the lateral force on the front wheel. yr Represents the lateral force of the rear wheel; (l f / v)γ represents the front axle sideslip compensation term, and the correction for additional front axle sideslip caused by yaw motion.

[0055] By rearranging the above equations and using the Laplace transform of a linear system, we can obtain the front wheel steering angle, rear wheel steering angle, and additional yaw moment (δ). f δ r M z ) to γ ​​and a y The transfer equation. The Laplace transform is an integral transform that transforms a function with time as the independent variable into a function with complex frequency as the independent variable. Considering the control system command value (δ) f cmd δ r cmd M z cmd ) and actual value (δ) f δ r M z There is a delay (τ) f , τ r , τ Mz The transfer equations for the entire system can be expressed as follows:

[0056] G γδf (s)=γ(s) / (δ f cmd (s))=(mv 2 C f l f s+C f C r lv) / (P(s))e -τfs ;

[0057] G γδr (s)=γ(s) / (δ r cmd (s))=(-mv 2 C r l r sC f C r lv) / (P(s))e -τrs ;

[0058] G γMz (s)=γ(s) / (M z cmd (s))=(mv 2 s+(C f v+C r v)) / (P(s))e -τ(Mz)s ;

[0059] G ayδf (s)=a y (s) / (δ f cmd (s))=(I z v 2 C f s 2 +C f C r l r lvs+C f C r lv 2 ) / (P(s))e -τfs ;

[0060] G ayδr (s)=a y (s) / (δ r cmd (s))=(I z v 2 C r s 2 +C f C r l f lvs-C f C r lv 2 ) / (P(s))e -τrs ;

[0061] G ayMz (s)=a y (s) / (M z cmd (s))=((C r l r v-C f l f v)s+(C f v 2 +C r v 2 )) / (P(s))e -τ(Mz)s ;

[0062] P(s)=mI z v 2 s 2 +(mvCf l f 2 +mvC r l r 2 +I z vC f +I z vC r )s+(mv 2 C r l r -mv 2 C f l f +C f C r l 2 ).

[0063] G γδf (s) represents the front wheel steering angle command δ f cmd The transfer equation to the vehicle's yaw rate γ; G γδr (s) represents the rear wheel steering angle command δ r cmd The transfer equation to the vehicle's yaw rate γ; G γ M z (s) indicates the additional yaw moment command M z cmd The transfer equation to the vehicle's yaw rate γ; G ayδf (s) represents the front wheel steering angle command δ f cmd The lateral acceleration of the whole vehicle a y The transfer equation of G; ayδr (s) represents the rear wheel steering angle command δ r cmd The lateral acceleration of the whole vehicle a y The transfer equation of G; ayMz (s) indicates the additional yaw moment command M z cmd The lateral acceleration of the whole vehicle a y The transfer equation; C f and C r These are the equivalent lateral stiffnesses of the front and rear axles of the vehicle; l=l f +l r The front and rear wheelbase is δ; v is the vehicle speed; δ is the y-axis. f and δ r These are the front wheel steering angle and the rear wheel steering angle, respectively; e -τfs e -τ(Mz)s e -τrsLet τf, τ(Mz), and τr represent the exponentiation of the equivalent delay times of the front-wheel steering, rear-wheel steering, and distributed drive torque vectoring systems, respectively, where τf, τ(Mz), and τr are the equivalent delay times of the front-wheel steering, rear-wheel steering, and distributed drive torque vectoring systems, respectively, and e -τfs e -τ(Mz)s e -τrs The time delay calculations represent the equivalent delay times of front wheel steering, rear wheel steering, and distributed drive torque vector system, respectively, with s representing the complex frequency domain variable in the time delay calculation.

[0064] mv 2 C f l f 's' indicates that the front wheels generate a yaw moment due to inertia during instantaneous steering; C f C r lv represents the steady-state yaw gain for front wheel steering; -mv 2 C r l r sC f C r lv indicates that rear-wheel steering has the opposite effect on yaw rate to front-wheel steering; mv 2 s represents the contribution of the yaw moment to the front axle lateral force due to the vehicle's lateral inertia; C f v+C r v represents the direct gain of the yaw moment on the steady-state yaw rate; I z v 2 C f s 2 This represents the high-frequency component of lateral acceleration directly generated by yaw inertia during front wheel steering; C f C r l r LVS represents the transient lateral acceleration generated by the elastic coupling of the front and rear tires; C f C r lv 2 Indicates the steady-state lateral acceleration gain caused by front wheel steering; I z v 2 C r s 2 This represents the high-frequency component of lateral acceleration directly generated by yaw inertia during rear-wheel steering; C f C r l f LVS represents the transient lateral acceleration generated by the elastic coupling of the front and rear tires when the rear wheels are steering; -C f C r lv 2 This represents the steady-state lateral acceleration gain caused by rear-wheel steering; (C) r l r vC f l fv)s represents the transient lateral acceleration generated by the yaw moment through the distribution of lateral forces between the front and rear axles; C f v 2 +C r v 2 This represents the steady-state lateral acceleration gain generated by the yaw moment;

[0065] mI z v 2 s 2 Let mI represent the inertia term, where mI z v 2 The coupled inertia represents the vehicle's mass and yaw inertia; (mvC) f l f 2 +mvC r l r 2 +I z vC f +I z vC r )s represents the damping term, where mvC f l f 2 The yaw damping, mvC, represents the lateral force generated by the front axle. r l r 2 I represents the yaw damping generated by the lateral force on the rear axle. z vC f I represents the damping contribution of the front axle lateral stiffness through the yaw moment of inertia. z vC r This represents the damping contribution of the rear axle lateral stiffness through the yaw inertia; mv 2 C r l r -mv 2 C f l f +C f C r l 2 Let mv represent the stiffness term, where mv 2 C r l r -mv represents the steady-state yaw moment generated by the lateral force on the rear axle. 2 C f l f C represents the steady-state yaw moment generated by the lateral force on the front axle. f C r l 2 This indicates the tire's elasticity recovery.

[0066] Taking a specific vehicle as an example, and conducting qualitative and quantitative analysis using the aforementioned transfer equations, we can obtain the following results: Vehicle mass m: 2926 kg; I z 6600Kg*m 2 (Kilograms multiplied by square meters represent a measure of the inertia of an object rotating about an axis); l f 1.555m (meters); l r : 1.545m; C f 236161 N / rad (Newtons per radian, representing the force required to produce a unit radian deformation); C r 242967 N / rad; τ f 0.05 sec (seconds); τ r : 0.08 sec; τ Mz : 0.04 sec.

[0067] Based on the above transfer equation, the front wheel rotation angle δ f cmd For anchoring, compare the rear wheel steering angle δ respectively. r cmd and additional yaw moment M z cmd Steady-state gain characteristics for steering motion:

[0068] ARSvsSBW:(G γδf / G γδr ) ss =(G ayδf ) / G ayδr ) ss =-1deg / deg;

[0069] TVvsSBW:(G γδf / G γMz ) ss =(G ayδf / G ayMz ) ss =(C f C r l) / (C f +C r =6480Nm / deg.

[0070] In this system, ARS stands for Active Rear-wheel Steering, SBW stands for Steer-by-Wire Front-wheel Steering, and TV stands for Distributed Torque Vectoring System; deg represents angle, and Nm represents Newton-meters.

[0071] The calculation results show that the rear wheel steering angle δ r cmd The impact on the steady-state attitude / trajectory of the vehicle is the same as the front wheel rotation angle δ. fcmd The effects are exactly the same, only in opposite directions; while to simulate the front wheel steering angle δ f cmd To achieve a steady-state cornering effect of 1 degree, the distributed drive torque vectoring system needs to output an additional yaw moment of approximately 6480 Nm. z cmd .

[0072] Therefore, it can be seen that the steady-state controllable range of the active rear-wheel steering (ARS) system is much greater than that of the distributed torque vectoring (TV) system, especially when a larger wheel-end angle is required at low and medium speeds. Furthermore, from a dynamics perspective, the active rear-wheel steering (ARS) mechanism is similar to that of steerable front-wheel steering (SBW), both achieving lateral control by changing the wheel-end angle with minimal impact on the vehicle's longitudinal coupling. In contrast, the distributed torque vectoring (TV) system indirectly achieves lateral control by generating additional yaw moment through longitudinal differential torque, but this also increases the longitudinal load on all four wheels, reducing longitudinal stability.

[0073] In addition to the steady-state analysis above, mathematical tools can be used to compare the impact characteristics of the three systems on the transient attitude / trajectory of the vehicle. Using the transfer equations mentioned above, the following can be obtained at different vehicle speeds: (δ f cmd δ r cmd M z cmd ) respectively for γ and a y The normalized step response can be specifically described as follows: Figures 2 to 7 As shown, Figure 2 This is a schematic diagram comparing the normalized step response of different control channels to yaw rate in one embodiment. Figure 3 This is a schematic diagram comparing the normalized step response of different control channels to yaw rate in another embodiment; Figure 4 This is a schematic diagram comparing the normalized step response of different control channels to yaw rate in another embodiment. Figure 5 This is a schematic diagram comparing the normalized step response of different control channels to lateral acceleration in one embodiment; Figure 6 This is a schematic diagram comparing the normalized step responses of different control channels to lateral acceleration in another embodiment; Figure 7 This is a schematic diagram comparing the normalized step response of different control channels to lateral acceleration in another embodiment.

[0074] in, Figures 2 to 7 The amplitude in the figure represents the lateral acceleration a. y The normalized value of the ratio between a and the steady-state value of lateral acceleration, representing the change of a over time. y The degree to which it reaches its own steady-state value.

[0075] Depend on Figures 2 to 7 It can be seen that the front wheel steering angle δ corresponding to SBW f cmd The rear wheel steering angle δ corresponding to ARS r cmd Additional yaw moment M corresponding to TV z cmd The transient response characteristics to yaw rate γ are similar, with the difference lying only in the delay variations between different actuators. However, their response to lateral acceleration a... y The dynamic response characteristics vary greatly. Among them, the rear wheel steering angle δ r cmd to a y The step response exhibits a large negative modulation (e.g.) Figures 5 to 7 The trough near Time=0.2, where the ratio of the maximum reverse offset to the final steady-state value is defined as negative tuning, indicates poor transient quality. This is due to the transfer equation G... ayδr (s) It can also be seen that the rear wheel steering angle δ r cmd to a y The system is a non-minimum phase zero-point system, which prevents it from responding smoothly to high dynamic inputs. Furthermore, the additional yaw moment M generated by the distributed drive torque vector TV... z to a y The step response exhibits excellent transient quality in both smoothness and response speed.

[0076] Therefore, it can be seen that the distributed drive torque vectoring (TV) response has a much stronger high dynamic steering capability than the active rear-wheel steering (ARS), and its advantage is mainly reflected in vehicle tracking performance (a y Meanwhile, the actuator (power motor) of the distributed drive torque vectoring system has a smaller response delay, which further enhances the advantages of distributed drive torque vectoring in dynamic response capability.

[0077] Based on the above steady-state and transient analyses, it can be seen that Active Rear-Wheel Steering (ARS) can provide a wider range of steady-state steering capabilities more economically and efficiently compared to Distributed Drive Torque Vectoring (TV). However, the shortcoming of Active Rear-Wheel Steering (ARS) lies in its dynamic steering tracking capability, namely, poor lateral acceleration smoothness during transient steering.

[0078] Step S206: Based on the physical constraints of the distributed drive torque vector system of the vehicle and the remaining steering angle compensation target, determine the additional yaw moment command; the physical constraints of the distributed drive torque vector system represent the constraints that the distributed drive torque vector system can provide yaw moment; the remaining steering angle compensation target represents the remaining steering angle compensation target of the total front wheel steering angle compensation target after allocating the rear wheel steering angle compensation target; the additional yaw moment command represents the command allocated to the distributed drive torque vector system of the vehicle.

[0079] Specifically, the vehicle control unit determines the rear wheel angle compensation target from the aforementioned total front wheel angle compensation target, and allocates the rear wheel angle compensation target to the rear wheel steering system. After determining the rear wheel angle command, the vehicle control unit can obtain the remaining angle compensation target from the aforementioned total front wheel angle compensation target after allocating the aforementioned rear wheel angle compensation target, and allocate the remaining angle compensation target to the distributed drive torque vector system. Combining the physical constraints of the distributed drive torque vector system, the additional yaw moment command is determined.

[0080] When the rear wheel steering angle compensation target cannot fully meet the front wheel steering angle total compensation target, the vehicle control unit can coordinate with the distributed drive torque vectoring system to supplement it by outputting yaw moment. Specifically, the vehicle control unit can obtain the difference between the front wheel steering angle total compensation target and the aforementioned rear wheel steering angle compensation target to determine the remaining steering angle compensation target. The remaining steering angle compensation target can be the remaining steering angle required to meet the front wheel steering angle total compensation target.

[0081] Among them, the vehicle control unit can rationally integrate the advantages of the two systems in steady-state and transient performance for different operating conditions, ultimately improving the vehicle's backup steering performance. The multi-system allocation strategy can be initially formulated as follows: prioritizing the front wheel steering angle total compensation target δ f total The low-frequency steady-state component δ f low (Rear wheel steering angle compensation target) is allocated to the active rear wheel steering ARS, and the remaining high-frequency transient component δ f high (The remaining steering angle compensation target) is supplemented by the distributed drive torque vector TV, which can be specifically expressed as: δ f total =δ f low +δ f high .

[0082] Considering that the allocation of steering targets must not exceed the capability boundary of any single system, the final front wheel steering angle compensation target δ allocated to the ARS is... f ARS It needs to be combined with δ f low Constraints of actuators related to the rear-wheel steering system are determined; the target δ for front wheel steering angle compensation ultimately allocated to the TV is determined. f TV It needs to be combined with δ f total -δ f ARS The actuator constraints associated with the distributed drive torque vectoring system are determined. Wherein, δ f total -δf ARS That is, the remaining corner compensation target.

[0083] The front wheel steering angle compensation targets (δ) allocated to ARS and TV respectively f ARS δ f TV ) must ultimately be converted into control commands (δ) for their respective systems. f cmd M z cmd The conversion process here can be referenced from the gain relationship of different control channels to steering motion.

[0084] Step S208: Control the vehicle steering according to the above-mentioned rear wheel steering angle command and the above-mentioned additional yaw moment command.

[0085] Among them, the vehicle control unit can control the actuators of the rear wheel steering system and the distributed drive torque vectoring system in the vehicle to work together according to the system instructions uniformly allocated by the fusion control, so as to realize the backup steering function.

[0086] The vehicle control unit receives the aforementioned rear wheel steering angle command δ. r cmd And the aforementioned additional yaw moment command M z cmd Then, the aforementioned rear wheel steering angle command δ can be applied. r cmd The additional yaw moment command M is sent to the active rear-wheel steering system. z cmd The commands are then sent to the distributed drive torque vectoring system. Subsequently, multiple systems, based on the control commands they receive, control the actuators corresponding to the rear-wheel steering system and the distributed drive torque vectoring system to achieve backup steering for the entire vehicle.

[0087] In the aforementioned vehicle control method, when the vehicle's steer-by-wire system malfunctions, the total front wheel angle compensation target is determined based on the steering wheel angle and the location of the front wheel angle fault. Based on the physical constraints of the rear wheel steering system, the rear wheel angle compensation target from the total front wheel angle compensation target is allocated to the rear wheel steering system to obtain the rear wheel angle command. Based on the physical constraints of the distributed drive torque vector system, the remaining angle compensation targets are allocated to the distributed drive torque vector system to determine the additional yaw moment command. Based on the rear wheel angle command and the additional yaw moment command, the vehicle steering is controlled. Compared to traditional single-system control backup steering, this application first identifies the total front wheel angle compensation target through vehicle backup steering, and then rationally allocates the total target to the active rear wheel steering system and the distributed drive torque vector system through a clear allocation strategy. This fully utilizes the performance advantage ranges of each system, enabling the vehicle to maintain its pre-fault steering performance to the maximum extent possible under the aforementioned fault conditions, thereby improving vehicle control safety.

[0088] In one embodiment, determining the total front wheel angle compensation target based on the real-time acquired steering wheel angle and front wheel angle fault location includes: determining the original front wheel angle command based on the vehicle's steering wheel angle and front gear ratio; determining the front wheel angle constraint range based on the road surface peak adhesion coefficient and the current steering gain; determining the front wheel angle command based on the comparison result between the original front wheel angle command and the front wheel angle constraint range; and obtaining the total front wheel angle compensation target based on the front wheel angle command and the front wheel angle fault location.

[0089] In this embodiment, the vehicle control unit can determine the original front wheel steering angle command based on the vehicle's steering wheel angle and front gear ratio; determine the front wheel steering angle range that satisfies driving rationality based on the peak road adhesion coefficient and current vehicle speed; and determine the front wheel steering angle command by comparing the original front wheel steering angle command with the front wheel steering angle constraint range. Since the front wheels may be at a non-straight angle when the drive-by-wire front wheel steering fails, the vehicle control unit can determine a reasonable front wheel steering angle command by combining the front wheel steering angle command and the location of the front wheel steering angle failure.

[0090] The peak coefficient of adhesion (PGI) can be related to the condition of the road surface in contact with the tire. For example, the PGI of dry cement road surface is 1.0, while that of wet cement road surface is 0.6. The higher the PGI, the better the tire's adhesion to the road surface.

[0091] Among them, the vehicle control unit first determines the steering wheel angle δ of the vehicle. hand The original front wheel steering angle command δ is determined by the front gear ratio Gear_Ratio. f raw Specifically, it can be represented as: δ f raw =δhand / Gear_Ratio.

[0092] Among them, the original front wheel steering angle command δ f raw Further measures are needed to constrain driving rationality and prevent irrational driving intentions from being controlled.

[0093] Specifically, the vehicle control unit can first determine the current peak road surface adhesion coefficient μ. road Estimate and determine the maximum lateral acceleration 'a' that the vehicle can achieve on the current road surface. ymax Specifically, it can be represented as: a ymax =0.8*μ road *g.

[0094] Using the front wheel steering angle δ f cmd Lateral acceleration a y Transfer equation steady-state gain G ayδf (Target transfer function corresponding to the current steering gain), calculate the maximum front wheel steering angle δ fLim (The boundary value of the front wheel steering angle constraint range) can be specifically expressed as:

[0095] δ fLim =a ymax / (G ayδf ) ss =(0.8*μ road *g*(mv 2 C r l r -mv 2 C f l f +C f C r l 2 )) / (C f C r lv 2 ).

[0096] Where, μ road Let represent the peak road adhesion coefficient, and g represent the gravitational acceleration. Thus, the vehicle control unit can obtain the front wheel steering angle constraint. Since the tires have left and right turning angles, the specific range of the front wheel steering angle constraint, representing the reasonable range of the front wheel steering angle, can be expressed as: [-δ fLim ,δ fLim ].

[0097] Compare with the original front wheel steering angle command δ f raw and front wheel steering angle constraint range [-δ fLim ,δ fLim If δ fraw When the steering angle exceeds the reasonable range, the front wheel steering angle command δ is applied. f cmd It is necessary to select boundary values ​​within a reasonable range.

[0098] Specifically, the total compensation target δ for front wheel steering angle f cmd =min[max(δ f raw ,-δ fLim ),δ fLim ].

[0099] Where max(δ) f raw ,-δ fLim This means that the original front wheel steering angle command is compared with the negative boundary value in the front wheel steering angle constraint range, and the larger value is taken. That is, if the original front wheel steering angle command is greater than the negative boundary value in the front wheel steering angle constraint range, then the original front wheel steering angle command is taken; otherwise, the negative boundary value in the front wheel steering angle constraint range is taken. min[max(δ f raw ,-δ fLim ),δ fLim ] indicates taking the maximum value of δ f raw ,-δ fLim ) and δ fLim The smaller of the two values ​​is used as the front wheel steering angle command. Furthermore, the location of any front wheel steering angle fault must be considered for correction.

[0100] Through this embodiment, the vehicle control unit can combine the original steering driving intention and driving rationality calculation to determine a reasonable front wheel steering angle command, thereby avoiding the execution of unreasonable driving target inputs and improving the safety of vehicle control.

[0101] In one embodiment, determining the front wheel steering angle constraint range based on the peak road adhesion coefficient and the current steering gain includes: determining the maximum lateral acceleration corresponding to the vehicle based on the peak road adhesion coefficient; determining the front wheel steering angle constraint range based on the target transfer function corresponding to the maximum lateral acceleration and the current steering gain; the function value of the target transfer function characterizes the degree of influence of the size of the front wheel steering angle of the vehicle on the lateral acceleration of the vehicle.

[0102] In this embodiment, the aforementioned front wheel steering angle constraint range can be predetermined by the vehicle control unit. The steering range corresponding to the front wheel steering angle constraint range may differ depending on the vehicle's state. For example, the vehicle control unit can determine the peak road adhesion coefficient based on the vehicle's current speed. The peak road adhesion coefficient represents the maximum value of the vehicle's adhesion to the road surface in the current state, indicating the degree of adhesion between the vehicle and the road surface. Different peak road adhesion coefficients result in different adhesion capabilities, thus affecting the vehicle's maximum lateral acceleration. Therefore, the vehicle control unit can determine the maximum permissible lateral acceleration based on the peak road adhesion coefficient. For example, the maximum permissible lateral acceleration is positively correlated with the peak road adhesion coefficient. The vehicle control unit determines the influence of the front wheel steering angle on the vehicle's lateral acceleration in steady-state analysis, using this as a target transfer function. Thus, the vehicle control unit can convert the maximum lateral acceleration into the aforementioned front wheel steering angle constraint range using the target transfer function.

[0103] Through this embodiment, the vehicle control unit can combine vehicle speed, road adhesion coefficient and target transfer function to determine the front wheel steering angle constraint range, thereby avoiding the output of unreasonable steering angles and improving the safety of vehicle control.

[0104] In one embodiment, obtaining the total front wheel angle compensation target based on the aforementioned front wheel angle command and the aforementioned front wheel angle fault location includes: determining the current front wheel angle of the vehicle based on the aforementioned front wheel angle fault location; and obtaining the total front wheel angle compensation target based on the aforementioned front wheel angle command and the aforementioned current front wheel angle.

[0105] In this embodiment, the front wheel steering angle command represents the theoretically required front wheel steering angle. However, when the steerable front wheel system fails, the front wheels may lock at the wrong angle. The vehicle control unit can obtain the current steering angle of the vehicle's front wheels as the current front wheel steering angle. Therefore, the vehicle control unit can combine the front wheel steering angle command with the current front wheel steering angle to determine the overall front wheel steering angle compensation target.

[0106] Specifically, the vehicle control unit can acquire the vehicle's steering wheel angle δ in real time. hand During normal driving, the steering wheel angle δ hand Mapped to front wheel steering angle command δ f cmd When the steer-by-wire malfunctions, the actual front wheel steering angle may lock at an abnormal position δ. f lock Therefore, the total compensation target for the front wheel steering angle is δ. f total The difference between the two should be: δ f total =δ fcmd -δ f lock .

[0107] Through this embodiment, the vehicle control unit can combine the front wheel steering angle command and the vehicle's current steering angle to determine the total front wheel steering angle compensation target, thereby improving the accuracy of determining the total front wheel steering angle compensation target.

[0108] In one embodiment, based on the physical constraints of the vehicle's rear-wheel steering system, determining the rear-wheel angle compensation target within the overall front-wheel angle compensation target, and allocating the rear-wheel angle compensation target to the vehicle's rear-wheel steering system to obtain a rear-wheel angle command, includes: extracting the low-frequency component of the overall front-wheel angle compensation target using a low-pass filter; determining the rear-wheel angle compensation target allocated to the rear-wheel steering system from the overall front-wheel angle compensation target based on the low-frequency component of the overall front-wheel angle compensation target, the vehicle's rear-wheel mechanical angle constraints, and mechanical thrust constraints; and determining the rear-wheel angle command based on the allocated rear-wheel angle compensation target and the steady-state gain relationship between the front-wheel angle and rear-wheel angle on the steering motion.

[0109] In this embodiment, the vehicle control unit can extract the low-frequency part of the total front wheel steering angle compensation target using a low-pass filter, and then combine it with the rear wheel mechanical steering angle constraint and mechanical thrust speed constraint to determine the part of the total front wheel steering angle compensation target allocated to the rear wheel as the rear wheel steering angle compensation target; the vehicle control unit determines the rear wheel steering angle command based on the rear wheel steering angle compensation target and the steady-state gain relationship between the front wheel steering angle and the rear wheel steering angle on the steering motion.

[0110] Specifically, in this example, the vehicle control unit uses a second-order adaptive low-pass filter F(s) to extract the total compensation target δ for the front wheel steering angle. f total The low-frequency steady-state portion of the filter. The Laplace transfer equation of the filter is as follows:

[0111] F(s) = ω n 2 (v) / (s 2 +2ω n (v)s+ω n 2 (v)).

[0112] Wherein, the filter cutoff frequency parameter ω n (v) Adapts to different vehicle speeds. ω n The parameter design process for (v) can be accomplished using step response analysis. Among these parameters, the cutoff frequency parameter ω... n(v) The design takes the maximum negative modulation of the step response as the key indicator, that is, at different vehicle speeds, after adding the target low-pass filter (corresponding to the system transfer equation G), ayδr (s)*F(s)), rear wheel steering δ r cmd To lateral acceleration a y The maximum negative modulation of the step response does not exceed 5%. Based on this negative modulation design specification, a unique filter cutoff frequency parameter value ω can be determined at a specific vehicle speed. n (v).

[0113] Specifically, the difference in the maximum negative modulation of the step response can be as follows: Figures 8 to 10 As shown, Figure 8 This is a schematic diagram illustrating how a low-pass filter improves the negative modulation of the rear wheel steering angle to lateral acceleration step response at a vehicle speed of 60 km / h. Figure 8 The filter cutoff frequency parameter ω n (60) = 3.64; Figure 9 This is a schematic diagram illustrating the negative modulation of the rear wheel steering angle to lateral acceleration step response at a vehicle speed of 80 km / h using a low-pass filter in another embodiment. Figure 9 The filter cutoff frequency parameter ω n (80) = 5.09; Figure 10 This is a schematic diagram illustrating how a low-pass filter improves the negative modulation of the rear wheel steering angle to lateral acceleration step response at a vehicle speed of 100 km / h, in another embodiment. Figure 10 The filter cutoff frequency parameter ω n (100) = 6.91. Wherein, Figures 8 to 10 The amplitude in the figure represents the lateral acceleration a. y The normalized value of the ratio between a and the steady-state value of lateral acceleration, representing the change of a over time. y The proportion of the population that has reached its steady-state value.

[0114] Total front wheel steering angle compensation target δ f total After passing through the above second-order adaptive filter, the low-frequency steady-state component of the overall compensation objective is obtained:

[0115] δ f low (s)=δ f total (s)*F(s).

[0116] Where, δ f low F(s) represents the low-frequency steady-state component of the total compensation target (assigned to the rear wheel steering system); F(s) represents the low-pass filter constraint.

[0117] Among them, common physical constraints of rear-wheel steering system ARS actuators include the maximum mechanical steering angle constraint δ. r max (Rear wheel mechanical steering angle constraint) and maximum mechanical thrust constraint δ' r max (Mechanical thrust constraint). From the above analysis, it can be seen that the front wheel steering angle δ f cmd With rear wheel steering angle δ r cmd Since the steady-state control gain relationships are the same in magnitude but opposite in direction, the physical constraints of the rear-wheel steering system can be directly used to apply the above-filtered δ. f low Further constraints are imposed, resulting in the front wheel steering angle compensation target δ allocated to ARS within the total front wheel steering angle compensation target. f ARS As the target for rear wheel steering angle compensation:

[0118] δ f ARS =Limit(δ f low ,δ r max ,δ' r max ).

[0119] That is, when the originally assigned target exceeds the executor's capability range, the boundary value corresponding to the executor's capability range is taken.

[0120] In this example, the vehicle control unit refers to the aforementioned front wheel steering angle δ. f cmd With rear wheel steering angle δ r cmd The steady-state control gain relationship can be expressed as:

[0121] (G γδf / G γδr ) ss =(G ayδf ) / G ayδr ) ss =-1deg / deg.

[0122] The vehicle control unit will allocate the front wheel steering angle compensation target δ to the ARS. f ARS Ultimately converted into the rear wheel steering angle command δ r cmd Specifically, it can be represented as: δ r cmd =-δ f ARS .

[0123] In this embodiment, the vehicle control unit combines the overall steering target with the adaptive low-pass filter design to distribute the overall steering target to the rear wheel steering. By referencing the capability boundary of the rear wheel steering system, it fully utilizes the steady-state performance advantages of rear wheel steering while avoiding the shortcomings of rear wheel steering in transient performance, thus preventing rear wheel steering from interfering with the vehicle's transient tracking performance and improving the accuracy of vehicle control.

[0124] In one embodiment, based on the physical constraints of the vehicle's distributed drive torque vector system, the remaining steering angle compensation target is allocated to the vehicle's distributed drive torque vector system to determine the additional yaw moment command, including: determining the original additional yaw moment command based on the remaining steering angle compensation target and the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion; and determining the additional yaw moment command based on the original additional yaw moment command and the yaw moment constraints corresponding to the distributed drive torque vector system.

[0125] In this embodiment, the vehicle control unit can allocate the remaining steering angle compensation target to the distributed drive torque vector system, and determine the additional yaw moment command by combining the physical constraints of the distributed drive torque vector system. Specifically, the vehicle control unit determines the portion of the total front wheel steering angle compensation target allocated to the distributed drive system based on the aforementioned total front wheel steering angle compensation target and its residual amount after allocation. Furthermore, based on the portion of the total front wheel steering angle compensation target allocated to the distributed drive system and the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on steering motion, the vehicle control unit determines the original additional yaw moment command. Thus, the vehicle control unit can determine the aforementioned additional yaw moment command based on the original additional yaw moment command and the ability of the distributed drive torque vector system to provide yaw moment constraints.

[0126] In this embodiment, the vehicle control unit allocates the difference between the total steering angle compensation requirement and the already allocated rear steering requirement to the distributed drive torque vectoring system. Referring to the capability boundary of the distributed drive torque vectoring system, it compensates for the high-frequency dynamic components of the driving intention as much as possible. This allows the vehicle to maintain its pre-fault steering performance to the maximum extent possible under the aforementioned fault conditions, thereby improving vehicle control safety.

[0127] In one embodiment, determining the original additional yaw moment command based on the aforementioned remaining steering angle compensation target and the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion includes: obtaining the target gain function corresponding to the aforementioned steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion; and determining the original additional yaw moment command based on the product of the aforementioned remaining steering angle compensation target and the function value of the aforementioned target gain function.

[0128] In this embodiment, the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on steering motion can be represented by a target gain function. This target gain function can be obtained by combining the vehicle's front axle equivalent lateral stiffness, rear axle equivalent lateral stiffness, and wheelbase. After obtaining the target gain function, the vehicle control unit can acquire the product of the remaining steering angle compensation target and the target gain function value. This is equivalent to multiplying the remaining steering angle compensation target by a corresponding coefficient to convert the remaining steering angle compensation target into a yaw moment. The vehicle control unit then obtains the original additional yaw moment command based on this product.

[0129] Specifically, in this example, the total compensation target δ for the front wheel steering angle is... f total and the portion δ already allocated to ARS f ARS Determine the residual target δ f TV (The remaining corner compensation target) is allocated to the distributed drive TV to supplement the high-frequency part of the steering demand, which can be specifically expressed as: δ f TV =δ f total -δ f ARS .

[0130] The vehicle control unit refers to the aforementioned front wheel steering angle δ f cmd With additional yaw moment M z cmd Steady-state control gain relationship: (G yδf / G yMz ) ss =(G ayδf / G ayMz ) ss =(C f C r l) / (C f +C r The front wheel steering angle compensation target δ will be allocated to the TV. f TV Calculate the original additional yaw moment command M z raw M z raw =δ f TV *(C f C r l) / (C f +C r ).

[0131] In this embodiment, the vehicle control unit can combine the target gain function and the remaining steering angle compensation target to determine the original additional yaw moment command, thereby improving the accuracy of the yaw moment command determination.

[0132] In one embodiment, obtaining the target gain function corresponding to the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion includes: obtaining the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase of the vehicle; and obtaining the target gain function based on the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase.

[0133] In this embodiment, the target gain function can be determined by combining the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase. The equivalent lateral stiffness of the front axle represents the ratio between the lateral force generated by the front axle and the front wheel slip angle when the two wheels of the front axle are considered as a whole; the equivalent lateral stiffness of the rear axle represents the ratio between the lateral force generated by the rear axle and the rear wheel slip angle when the two wheels of the rear axle are considered as a whole; and the wheelbase represents the horizontal distance between the centers of the front and rear wheels of the vehicle. The vehicle control unit can obtain the target gain function by combining the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase.

[0134] Specifically, the front wheel steering angle δ f cmd With additional yaw moment M z cmd The target gain function corresponding to the steady-state control gain relationship is expressed as: (G yδf / G yMz ) ss =(G ayδf / G ayMz ) ss =(C f C r l) / (C f +C r ), C f and C r These are the equivalent lateral stiffnesses of the front and rear axles, respectively; l=l f +l r This refers to the front and rear wheelbase. The value of the target gain function can be an equivalent coefficient, given the front wheel steering angle δ. f cmd With additional yaw moment M z cmd The steady-state control gain relationship is that the greater the equivalent lateral stiffness of the front and rear axles, the larger the equivalent coefficient, indicating that the tires are "harder". The longer the wheelbase, the larger the equivalent coefficient, because the lever arm is longer, and the same front wheel steering angle requires a larger additional yaw moment to achieve the same effect.

[0135] In this embodiment, the vehicle control unit can determine the target gain function by combining the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase. Thus, the vehicle control unit determines the yaw moment command by combining the target gain function, thereby improving the accuracy of the yaw moment command determination.

[0136] In one embodiment, obtaining the target gain function based on the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase includes: determining the overall vehicle lateral stiffness corresponding to the vehicle based on the equivalent lateral stiffness of the front axle and the equivalent lateral stiffness of the rear axle; and obtaining the target gain function based on the overall vehicle lateral stiffness and the wheelbase.

[0137] In this embodiment, when determining the target gain function, the vehicle control unit can combine the front axle equivalent lateral stiffness, the rear axle equivalent lateral stiffness, and the wheelbase to determine the target gain function based on the relationship between the vehicle's wheel axles and its ability to resist lateral slippage. Specifically, the vehicle control unit can determine the overall vehicle lateral stiffness based on the aforementioned front axle and rear axle equivalent lateral stiffness. For example, the vehicle control unit obtains the product of the front axle and rear axle equivalent lateral stiffness, divides this product by the sum of the front and rear axle equivalent lateral stiffness, and obtains the overall vehicle lateral stiffness. The overall vehicle lateral stiffness characterizes the vehicle's overall ability to resist lateral slippage. The vehicle control unit can further obtain the target gain function based on the overall vehicle lateral stiffness and the wheelbase. For example, the vehicle control unit multiplies the overall vehicle lateral stiffness by the wheelbase to obtain the target gain function.

[0138] Specifically, the target gain function represented by the above steady-state control gain relationship can be expressed as:

[0139] (G yδf / G yMz ) ss =(G ayδf / G ayMz ) ss =(C f C r l) / (C f +C r ).

[0140] Among them, G γδf G represents the effect of front wheel steering on the turning speed of the entire vehicle. γ M z G represents the effect of the torque vector on the turning speed of the vehicle. ayδf G represents the effect of front wheel steering on the lateral acceleration of the vehicle. ayMz C represents the effect of the torque vector on the lateral acceleration of the vehicle. f and C rC represents the equivalent lateral stiffness of the front and rear axles, respectively, and l is the wheelbase between the front and rear wheels of the vehicle. f C r / (C f +C r () indicates the lateral stiffness of the entire vehicle.

[0141] In this embodiment, the vehicle control unit can determine the target gain function by combining the equivalent lateral stiffness of the front axle, the equivalent lateral stiffness of the rear axle, and the wheelbase. Thus, the vehicle control unit determines the yaw moment command by combining the target gain function, thereby improving the accuracy of the yaw moment command determination.

[0142] In one embodiment, determining the additional yaw moment command based on the original additional yaw moment command and the yaw moment constraint corresponding to the distributed drive torque vector system includes: if the value of the original additional yaw moment command is within the range of the yaw moment constraint, then the original additional yaw moment command is determined to be the additional yaw moment command; if the value of the original additional yaw moment command is less than or equal to the minimum value of the yaw moment constraint, then the minimum value of the yaw moment constraint is determined to be the additional yaw moment command; if the value of the original additional yaw moment command is greater than or equal to the maximum value of the yaw moment constraint, then the maximum value of the yaw moment constraint is determined to be the additional yaw moment command.

[0143] In this embodiment, for different initial additional yaw moment commands, the vehicle control unit can determine the final additional yaw moment command by combining the range of yaw moment constraints with the initial additional yaw moment command. Specifically, the vehicle control unit can compare the value of the initial additional yaw moment command with the range of the aforementioned yaw moment constraints. If the value of the initial additional yaw moment command is within the range of the aforementioned yaw moment constraints, it means that the value of the initial additional yaw moment command is greater than the minimum value and less than the maximum value of the range of yaw moment constraints. In this case, the vehicle control unit determines the initial additional yaw moment command as the final additional yaw moment command.

[0144] If the value of the original additional yaw moment command is less than or equal to the minimum value of the yaw moment constraint, it indicates that the value of the original additional yaw moment command is too small. In this case, the vehicle control unit determines that the minimum value of the yaw moment constraint is the aforementioned additional yaw moment command. If the value of the original additional yaw moment command is greater than or equal to the maximum value of the aforementioned yaw moment constraint, it indicates that the value of the original additional yaw moment command is too large. In this case, the vehicle control unit determines that the maximum value of the aforementioned yaw moment constraint is the aforementioned additional yaw moment command.

[0145] Specifically, the vehicle control unit, based on the original additional yaw moment command M zcmd Based on the actuator's capability range, the final additional yaw moment command is output:

[0146] M z cmd =min[max(M z raw M z min ),M z max ].

[0147] Among them, M z cmd This indicates an additional yaw moment command. max(M z raw M z min This indicates that the larger value is taken between the original additional yaw moment command and the minimum value within the yaw moment constraint range. That is, if the original additional yaw moment command is greater than the minimum value within the yaw moment actuator constraint range, then the original additional yaw moment command is taken; otherwise, the minimum value within the yaw moment actuator constraint range is taken. z raw M z min ),M z max ] indicates taking the maximum value of M. z raw M z min ) and M z max The smaller of the two values ​​is taken as the final additional yaw moment command. That is, when the original additional yaw moment command exceeds the actuator's capability range, the boundary value corresponding to the actuator's capability range is taken.

[0148] Through this embodiment, the vehicle control unit can determine the additional yaw moment command by comparing the original additional yaw moment command with the yaw moment constraint range, thereby improving the rationality of the additional yaw moment command.

[0149] In one embodiment, the step of determining the yaw moment constraint includes: obtaining the number of motors of the vehicle, the maximum permissible output torque of the motors, and the output torque of the motors; obtaining the maximum adhesion between the vehicle's tires and the road surface, the allocated torque of the tires, and the remaining distributable torque of the tires; and determining the yaw moment constraint based on the number of motors, the maximum permissible output torque, the output torque, the maximum adhesion, the allocated torque, and the remaining distributable torque.

[0150] In this embodiment, the vehicle control unit can determine the yaw moment constraint from multiple perspectives. Specifically, the vehicle control unit can acquire parameters related to the vehicle's power motors, such as the number of power motors, the maximum permissible output torque of the power motors, and the torque already output by the power motors. The vehicle control unit can also acquire tire-related parameters, such as the maximum adhesion between the tires and the road surface, the allocated torque corresponding to the tires, and the remaining distributable torque corresponding to the tires. Therefore, the vehicle control unit can determine the yaw moment constraint based on the number of power motors, the maximum permissible output torque, the already output torque, the maximum adhesion, the allocated torque, and the remaining distributable torque.

[0151] Specifically, the physical constraints (yaw moment constraints) commonly encountered by distributed drive torque vectoring (TV) actuators depend on many factors, including the vehicle's electrical configuration (number of actuators), the motor's output torque capability (maximum power), the maximum adhesion between the tires and the road surface, the torque already distributed to the four wheels during longitudinal vehicle motion (acceleration and deceleration), and the additional torque margin that can be added to the four wheels longitudinally. Define M z Min M is the minimum additional yaw torque that the actuator can provide (positive for counterclockwise, negative for clockwise). z Max To obtain the maximum additional yaw moment that the actuator can provide, the yaw moment constraint [M] is obtained. z Min M z Max ].

[0152] In this embodiment, the vehicle control unit combines multiple dimensions to determine the yaw moment constraint of the vehicle, thereby improving the accuracy of the yaw moment constraint.

[0153] In one exemplary embodiment, such as Figure 11 As shown, Figure 11 This is a flowchart illustrating the vehicle control method in another embodiment. By developing control software according to this flowchart and the aforementioned control method and control device embodiments, the improvement in backup steering performance achieved by the aforementioned fusion control scheme can be verified.

[0154] In this embodiment, the vehicle control unit achieves steering in the event of front-wheel steer failure through a fusion backup steering system combining active rear-wheel steering and distributed drive torque vectoring. The core principle is to rationally utilize the strengths of both systems in steady-state and dynamic performance for different operating conditions, ultimately improving the overall vehicle's backup steering performance.

[0155] Specifically, the vehicle control unit identifies front wheel steering faults. When a front wheel steering fault is detected, backup steering is enabled. Backup steering enable indicates that the vehicle control unit has detected a front wheel steering fault and that the fusion backup steering system based on active rear wheel steering and distributed drive torque vectoring is ready, allowing steering control to be transferred from front wheel steering to the aforementioned backup steering system.

[0156] When the vehicle control unit performs steering based on the aforementioned backup steering system, it can perform online vehicle state estimation, which includes acquiring various signals corresponding to the vehicle. For example, during online vehicle state estimation, the vehicle control unit can acquire externally input signals. Specifically, the backup steering function, at the upper-level fusion control layer, mainly acquires the following input signals: the fault status of the steerable front wheels, the fault angle of the front wheels (current front wheel angle), the redundancy backup steering function enable, the steering wheel angle input, the reference vehicle speed (such as the current vehicle speed), the peak road adhesion coefficient, the available range of motor torque, and the available longitudinal margin of the four wheels (four-wheel longitudinal margin). During the steering process through the backup steering system, the vehicle control unit inputs the parameters acquired from the online vehicle state estimation at the corresponding execution steps to execute the corresponding steps.

[0157] When determining the overall compensation target for the front wheel steering angle, the vehicle control unit combines the driving target constraints (front wheel steering angle constraint range) to determine the compensation target. Specifically, the vehicle control unit first calculates the original front wheel steering angle command based on the steering wheel angle and the drive-by-wire transmission ratio: δ f raw =δ hand / Gear_Ratio. Where, δ f raw Indicates the original front wheel steering angle command; δ hand The steering wheel angle is represented by Gear_Ratio, which represents the ratio of the steering wheel angle to the drive-by-wire front wheel rotation. This ratio can be determined based on the structural characteristics of the drive-by-wire front wheel rotation.

[0158] The vehicle control unit estimates the current vehicle speed and the peak road surface adhesion coefficient, using the front wheel steering angle δ. f cmd To lateral acceleration a y The steady-state gain of the transfer equation is used to calculate the maximum front wheel steering angle range (the boundary value of the front wheel steering angle constraint range). This further constrains the original front wheel steering angle command, avoiding the execution of unreasonable driving target inputs. The boundary value of the front wheel steering angle constraint range can be expressed as:

[0159] δ fLim =a ymax / (G ayδf ) ss =(0.8*μ road*g*(mv 2 C r l r -mv 2 C f l f +C f C r l 2 )) / (C f C r lv 2 ).

[0160] Where, μ road G represents the peak adhesion coefficient of the road surface. ayδf This represents the effect of front wheel steering on the lateral acceleration of the entire vehicle, where g represents gravitational acceleration. From the above formula, it can be seen that the front wheel steering angle constraint range (driving target constraint) is related to the peak road adhesion coefficient and the reference vehicle speed. Therefore, the vehicle control unit can obtain the front wheel steering angle constraint range. Since the tires have left and right turning angles, the front wheel steering angle constraint range can be specifically expressed as: [-δ fLim ,δ fLim ].

[0161] The vehicle control unit combines the above [-δ] fLim ,δ fLim This further determines the front wheel steering angle command (target front wheel steering angle). The front wheel steering angle command can be specifically expressed as:

[0162] δ f cmd =min[max(δ f raw ,-δ fLim ),δ fLim ].

[0163] Where max(δ) f raw ,-δ fLim The expression () indicates that the original front wheel steering angle is compared with the negative boundary value within the front wheel steering angle constraint range, and the larger value is taken. That is, if the original front wheel steering angle is greater than the negative boundary value within the front wheel steering angle constraint range, then the original front wheel steering angle is taken; otherwise, the negative boundary value within the front wheel steering angle constraint range is taken. min[max(δ f raw ,-δ fLim ),δ fLim ] indicates taking the maximum value of δ f raw ,-δ fLim ) and δ fLim The smaller of the two values ​​is used as the front wheel steering angle command.

[0164] The vehicle control unit further corrects the angle based on the current front wheel steering angle. Specifically, due to the failure of the steer-by-wire front wheels, the front wheels may lock at the incorrect angle position δ. f lock The total front wheel steering angle (total front wheel steering angle compensation target, also known as the front wheel target correction angle) that the vehicle control unit needs to compensate for through active rear wheel steering and distributed drive torque vectoring is: δ f total =δ f cmd -δ f lock Among them, δ f cmd This indicates the front wheel steering angle command.

[0165] When the vehicle control unit determines the demand for active rear-wheel steering, the comparative analysis of the above system characteristics shows that, compared with distributed drive torque vectoring, active rear-wheel steering can provide a more economical and efficient steady-state steering capability over a wider range. However, the shortcoming of active rear-wheel steering lies in its dynamic steering tracking capability, i.e., the lateral acceleration 'a' under transient steering. y The smoothness is poor. Therefore, when considering the division of labor in the integrated system, efforts should be made to avoid allocating the high-frequency components of steering requirements to the rear wheels. For the total front wheel steering angle correction requirement δ... f total (Total front wheel steering angle compensation target) The vehicle control unit can perform speed-sensitive adaptive low-pass filtering (i.e., low-pass filtering combined with the reference vehicle speed). For example, the vehicle control unit can use a low-pass filter to extract the low-frequency fundamental component (such as steering requirements with slow change frequency) from the total front wheel steering angle compensation target and allocate it to the active rear wheel steering, as δ. r cmd (Rear wheel steering angle command). Then, the distributed drive torque vectoring system adds a yaw moment M. z cmd (Additional yaw moment command) effectively supplements the remaining high-frequency part of the total front wheel steering angle compensation target.

[0166] The vehicle control unit can use a second-order adaptive low-pass filter as the target low-pass filter constraint to ensure effective filtering of high-frequency input components. The target low-pass filter constraint can be expressed as:

[0167] F(s) = ω n 2 (v) / (s 2 +2ω n (v)s+ω n 2 (v)).

[0168] Wherein, the filter cutoff frequency parameter ω n(v) Adapts to different vehicle speeds. ω n The parameter design process for (v) can be accomplished using step response analysis. The vehicle control unit uses the maximum negative modulation of the step response as a key indicator, that is, at different vehicle speeds, the maximum negative modulation of the step response after adding the target low-pass filter (corresponding to the system transfer equation G). ayδr (s)*F(s)), rear wheel steering δ r cmd To lateral acceleration a y The maximum negative modulation of the step response does not exceed 5%.

[0169] Thus, the vehicle control unit obtains the target total front wheel steering angle compensation δ f total Then, by passing through the target low-pass filter page number, the low-frequency component of the total front wheel steering angle compensation target allocated to the active rear wheel steering can be expressed as: δ f low (s)=δ f total (s)*F(s).

[0170] Where, δ f low F(s) represents the low-frequency component of the total front wheel steering angle compensation target; F(s) represents the target low-pass filter constraint. The vehicle control unit then determines the rear wheel steering angle command based on the low-frequency component of the total front wheel steering angle compensation target. This determination may be combined with the mechanical constraints of active rear wheel steering (rear steering actuator mechanical constraints).

[0171] From the above analysis, the relationship between the control gain of the front wheel steering angle and the rear wheel steering angle is as follows:

[0172] (G ayδf / G ayδr ) ss =-1deg / deg.

[0173] Since they are the same size but opposite in direction, the vehicle control unit can directly use the maximum mechanical steering angle δ of the rear wheel steering actuator. r max With maximum mechanical thrust δ' r max , for δ f low By applying constraints, the target for rear wheel steering angle compensation is obtained. The target for rear wheel steering angle compensation (rear wheel equivalent to front wheel corrected steering angle) can be specifically expressed as:

[0174] δ f ARS =Limit(δ f low ,δ r max ,δ'r max ).

[0175] The vehicle control unit can combine the aforementioned equivalent front wheel steering angle correction for the rear wheels to adjust the active rear wheel steering channel gain. For example, based on the control gain relationship, the vehicle control unit can obtain the rear wheel steering angle command that the active rear wheel steering system needs to output in the fusion control, which can be expressed as: δ r cmd =-δ f ARS Among them, δ f ARS Indicates the target for rear wheel steering angle compensation, δ' r max This indicates the maximum mechanical rotation angle δ r max The derivative of δ; r cmd This indicates the rear wheel steering angle command after direction correction.

[0176] When the vehicle control unit supplements the yaw moment through the distributed drive torque vectoring system, for the remaining steering angle compensation target, due to the total front wheel steering angle compensation target δ f total The portion allocated to active rear-wheel steering is δ f ARS Therefore, the remaining supplementary part of the distributed drive torque vector system can be expressed as: δ f TV =δ f total -δ f ARS Among them, δ f TV This indicates the remaining steering angle compensation target (yaw moment equivalent to front wheel correction angle).

[0177] The vehicle control unit can combine the aforementioned yaw moment equivalent front wheel correction angle to perform distributed drive torque vector channel gain. For example, the vehicle control unit obtains the remaining steering angle compensation target δ. f TV Therefore, based on the above analysis, the relationship between the front wheel steering angle and the additional yaw moment control gain is as follows:

[0178] (G ayδf / G ayMz ) ss =(C f C r l) / (C f +C r ).

[0179] Therefore, the remaining angle compensation target is converted into yaw moment M. z After the control channel:

[0180] M z raw =δ f TV *(C f C r l) / (C f +C r ).

[0181] Among them, M z raw This indicates the original additional yaw moment command.

[0182] To ensure that the determined additional yaw moment command is within a reasonable range, the vehicle control unit can determine the additional yaw moment command in conjunction with the constraints of the distributed drive torque vector actuator. For example, the vehicle control unit pre-determines the constraints of the yaw moment actuator, which are based on one or more of the following: the vehicle's electrical configuration, the output torque range of the motor (motor torque range), the motor's already output torque, the allocated torque corresponding to the vehicle's longitudinal movement, the maximum adhesion between the vehicle's tires and the road surface, and the torque margin corresponding to the vehicle's tires (four-wheel longitudinal margin); the torque margin represents the value of the torque that can be added to the vehicle's tires. That is, without changing the longitudinal vehicle speed, the capability boundary (M...) of the yaw moment actuator in the distributed drive torque vector system... z min M z max The calculation of M depends primarily on the following factors: vehicle powertrain configuration, the maximum allowable output torque range of the current power motor (output torque range), the torque already allocated to the current basic longitudinal control motor, the current maximum adhesion between the four wheels and the road surface (maximum adhesion between the vehicle's tires and the road surface), the torque already allocated to the four wheels under the current basic longitudinal control, and the current additional torque margin for the four wheels (torque margin corresponding to the vehicle's tires). Among these, M... z min M represents the minimum range of constraints for the yaw moment actuator. z max This indicates the maximum range of the yaw moment constraint.

[0183] After the vehicle control unit passes the capability boundary constraints of the yaw moment actuator, the output is the final additional yaw moment command, which can be specifically expressed as:

[0184] M z cmd =min[max(M z raw M z min ),M zmax ].

[0185] Among them, M z cmd This indicates an additional yaw moment command. max(M z raw M z min This indicates that the larger value is taken between the original additional yaw moment command and the minimum value within the yaw moment constraint range. That is, if the original additional yaw moment command is greater than the minimum value within the yaw moment constraint range, then the original additional yaw moment command is taken; otherwise, the minimum value within the yaw moment constraint range is taken. min[max(M z raw M z min ),M z max ] indicates taking the maximum value of M. z raw M z min ) and M z max The smaller of the two values ​​is used as the additional yaw moment command.

[0186] After receiving the aforementioned rear wheel steering angle command and additional yaw moment command, the vehicle control unit can control the command output. For example, after the redundant backup steering function is activated, the vehicle control unit performs upper-level fusion control calculations and finally outputs the rear wheel steering angle command δ. r cmd Additional yaw moment command (Additional yaw moment command) M z cmd The vehicle control unit performs rear wheel steering lower-level control and distributed drive torque vectoring lower-level control separately. For example, the vehicle control unit sends the rear wheel steering angle command δ... r cmd and additional yaw moment command M z cmd The information is respectively provided to the active rear-wheel steering system and the distributed drive torque vectoring system for arbitration and execution.

[0187] Thus, the vehicle control unit makes full use of the vehicle's existing active rear-wheel steering and distributed drive torque vectoring subsystems, and formulates a collaborative strategy through upper-level algorithms to integrate the respective advantages of active rear-wheel steering and distributed drive torque vectoring, thereby improving the overall vehicle performance in backup steering mode without increasing hardware costs.

[0188] Specific control benefits, such as Figures 12 to 15 As shown. Among them, Figure 12 This is a schematic diagram illustrating the yaw rate performance gains of a step-steering vehicle in one embodiment. Figure 13This is a schematic diagram illustrating the lateral acceleration performance gains of a step-steering vehicle in one embodiment; Figure 14 This is a schematic diagram of a step steering rear wheel angle control command in one embodiment; Figure 15 This is a schematic diagram of a step steering additional yaw moment control command in one embodiment. Figures 12 to 15 As shown, compared to using only a single control system for backup steering, the integrated control of the dual systems including Active Rear Wheel Steering (ARS) and Distributed Drive Torque Vectoring (TV) significantly improves the overall performance of backup steering, more closely reproducing the basic forward steering characteristics of the vehicle when it is not malfunctioning.

[0189] in, Figure 14 In the case of non-faulty basic front wheel steering and single TV backup steering, the ARS does not need to output control commands. At this time, the steering angles corresponding to non-faulty basic front wheel steering and single TV backup steering are both 0. Figure 15 In the case of non-faulty basic front wheel steering and single ARS backup steering, the TV does not need to output control commands. At this time, the yaw moment corresponding to non-faulty basic front wheel steering and single ARS backup steering is 0.

[0190] Alternatively, further modifications and extensions could be made to the current embodiment. One possible direction is to simultaneously introduce closed-loop control of vehicle steering motion, using the vehicle-wide measurement values ​​from the onboard inertial measurement unit (IMU) to construct a multi-input multiple output (MIMO) system, thereby enhancing the closed-loop tracking capability of the vehicle's basic steering characteristics when not malfunctioning during backup steering.

[0191] Through the above embodiments, when the vehicle's steer-by-wire system malfunctions, the rear-wheel steering system and the distributed drive torque vectoring system are integrated to effectively correct abnormal front wheel steering angle deviations at the vehicle level, thereby achieving backup steering. This allows the vehicle to maintain its steering performance before the abnormality to the maximum extent possible under the aforementioned fault conditions, thus improving the vehicle's control safety.

[0192] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0193] Based on the same inventive concept, this application also provides a vehicle control device for implementing the vehicle control method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more vehicle control device embodiments provided below can be found in the limitations of the vehicle control method described above, and will not be repeated here.

[0194] In one exemplary embodiment, such as Figure 16 As shown, a vehicle control device is provided, including: an acquisition module 500, a first calculation module 502, a second calculation module 504, and a control module 506, wherein:

[0195] The acquisition module 500 is used to activate the fusion backup steering function when the vehicle's steer-by-wire system fails. It determines the total compensation target for the front wheel angle based on the real-time acquired steering wheel angle and the fault location of the front wheel angle.

[0196] The first calculation module 502 is used to determine the rear wheel angle compensation target in the total front wheel angle compensation target according to the physical constraints of the rear wheel steering system of the vehicle, and to allocate the rear wheel angle compensation target to the rear wheel steering system of the vehicle to obtain the rear wheel angle command.

[0197] The second calculation module 504 is used to allocate the remaining steering angle compensation target to the distributed driving torque vector system of the vehicle according to the physical constraints of the vehicle's distributed driving torque vector system, and determine the additional yaw moment command; the remaining steering angle compensation target represents the remaining steering angle compensation target of the total front wheel steering angle compensation target after allocating the rear wheel steering angle compensation target.

[0198] The control module 506 is used to control the steering of the vehicle according to the aforementioned rear wheel steering angle command and the aforementioned additional yaw moment command.

[0199] In one embodiment, the acquisition module 500 is configured to: determine the original front wheel angle command based on the vehicle's steering wheel angle and front gear ratio; determine the front wheel angle constraint range based on the road surface peak adhesion coefficient and the current steering gain; determine the front wheel angle command based on the comparison between the original front wheel angle command and the front wheel angle constraint range; and obtain the total front wheel angle compensation target based on the front wheel angle command and the front wheel angle fault location.

[0200] In one embodiment, the first calculation module 502 is used to determine the maximum lateral acceleration corresponding to the vehicle based on the peak road adhesion coefficient; and to determine the front wheel steering angle constraint range based on the target transfer function corresponding to the maximum lateral acceleration and the current steering gain; the function value of the target transfer function characterizes the degree of influence of the size of the front wheel steering angle of the vehicle on the lateral acceleration of the vehicle.

[0201] In one embodiment, the acquisition module 500 is used to determine the current front wheel angle of the vehicle based on the location of the front wheel angle fault; and to obtain the total front wheel angle compensation target based on the front wheel angle command and the current front wheel angle.

[0202] In one embodiment, the first calculation module 502 is configured to extract the low-frequency component of the total front wheel angle compensation target using a low-pass filter; determine the rear wheel angle compensation target allocated to the rear wheel steering system from the total front wheel angle compensation target based on the low-frequency component of the total front wheel angle compensation target, the rear wheel mechanical angle constraint and mechanical thrust constraint of the vehicle; and determine the rear wheel angle command based on the rear wheel angle compensation target allocated to the rear wheel angle compensation target and the steady-state gain relationship between the front wheel angle and the rear wheel angle on the steering motion.

[0203] In one embodiment, the second calculation module 504 is used to determine the original additional yaw moment command based on the remaining steering angle compensation target and the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion; and to determine the additional yaw moment command based on the original additional yaw moment command and the yaw moment constraint corresponding to the distributed drive torque vector system.

[0204] In one embodiment, the second calculation module 504 is used to obtain the target gain function corresponding to the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion; and to determine the original additional yaw moment command based on the product of the remaining steering angle compensation target and the function value of the target gain function.

[0205] In one embodiment, the second calculation module 504 is used to obtain the front axle equivalent lateral stiffness, rear axle equivalent lateral stiffness, and wheelbase of the vehicle; and to obtain the target gain function based on the front axle equivalent lateral stiffness, rear axle equivalent lateral stiffness, and wheelbase.

[0206] In one embodiment, the second calculation module 504 is used to determine the vehicle lateral stiffness corresponding to the vehicle based on the equivalent lateral stiffness of the front axle and the equivalent lateral stiffness of the rear axle; and to obtain the target gain function based on the vehicle lateral stiffness and the wheelbase.

[0207] In one embodiment, the second calculation module 504 is configured to: if the value of the original additional yaw moment command is within the range of the yaw moment constraint, determine that the original additional yaw moment command is the additional yaw moment command; if the value of the original additional yaw moment command is less than or equal to the minimum value of the yaw moment constraint, determine that the minimum value of the yaw moment constraint is the additional yaw moment command; and if the value of the original additional yaw moment command is greater than or equal to the maximum value of the yaw moment constraint, determine that the maximum value of the yaw moment constraint is the additional yaw moment command.

[0208] In one embodiment, the second calculation module 504 is used to obtain the number of power motors of the vehicle, the maximum allowable output torque of the power motors, and the output torque of the power motors; to obtain the maximum adhesion between the vehicle's tires and the road surface, the allocated torque of the tires, and the remaining allocateable torque of the tires; and to determine the yaw moment constraint based on the number of power motors, the maximum allowable output torque, the output torque, the maximum adhesion, the allocated torque, and the remaining allocateable torque.

[0209] Each module in the aforementioned vehicle control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the electronic device in hardware form or independent of it, or stored in the memory of the electronic device in software form, so that the processor can call and execute the operations corresponding to each module.

[0210] In one exemplary embodiment, an electronic device is provided, which may be a vehicle control unit, and its internal structure diagram may be as follows: Figure 17As shown, this electronic device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores vehicle constraint data. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements a vehicle control method.

[0211] Those skilled in the art will understand that Figure 17 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the electronic device to which the present application is applied. The specific electronic device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0212] In one exemplary embodiment, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the vehicle control method described above.

[0213] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the vehicle control method described above.

[0214] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the vehicle control method described above.

[0215] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0216] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0217] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0218] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A vehicle control method, characterized in that, The method includes: When the vehicle's steer-by-wire system malfunctions, the fusion backup steering function is activated. Based on the real-time acquired steering wheel angle and the location of the front wheel angle malfunction, the total front wheel angle compensation target is determined. The total front wheel angle compensation target represents the required rotation angle of the vehicle's front wheels. Based on the physical constraints of the vehicle's rear wheel steering system, the rear wheel angle compensation target in the total front wheel angle compensation target is determined, and the rear wheel angle compensation target is assigned to the vehicle's rear wheel steering system to obtain the rear wheel angle command; the physical constraints of the rear wheel steering system include the vehicle's rear wheel mechanical angle constraint and mechanical thrust constraint. Based on the physical constraints of the vehicle's distributed drive torque vector system and the remaining steering angle compensation target, an additional yaw moment command is determined; the physical constraints of the distributed drive torque vector system represent the constraints that the distributed drive torque vector system can provide yaw moment; the remaining steering angle compensation target represents the remaining steering angle compensation target of the total front wheel steering angle compensation target after allocating the rear wheel steering angle compensation target; the additional yaw moment command represents the command allocated to the vehicle's distributed drive torque vector system. The vehicle steering is controlled according to the rear wheel steering angle command and the additional yaw moment command.

2. The method according to claim 1, characterized in that, The step of determining the total compensation target for the front wheel angle based on the real-time acquired steering wheel angle and front wheel angle fault location includes: The original front wheel steering angle command is determined based on the vehicle's steering wheel angle and front drive ratio; The front wheel steering angle constraint range is determined based on the peak road adhesion coefficient and the current steering gain. Based on the comparison between the original front wheel steering angle command and the front wheel steering angle constraint range, the front wheel steering angle command is determined; Based on the front wheel steering angle command and the location of the front wheel steering angle fault, the total compensation target for the front wheel steering angle is obtained.

3. The method according to claim 2, characterized in that, The determination of the front wheel steering angle constraint range based on the peak road adhesion coefficient and the current steering gain includes: The maximum lateral acceleration corresponding to the vehicle is determined based on the peak road adhesion coefficient. The front wheel steering angle constraint range is determined based on the target transfer function corresponding to the maximum lateral acceleration and the current steering gain; the function value of the target transfer function characterizes the degree of influence of the size of the vehicle's front wheel steering angle on the vehicle's lateral acceleration.

4. The method according to claim 2, characterized in that, The step of obtaining the total front wheel steering angle compensation target based on the front wheel steering angle command and the location of the front wheel steering angle fault includes: Based on the location of the front wheel steering angle fault, determine the current front wheel steering angle of the vehicle; Based on the front wheel steering angle command and the current front wheel steering angle, the total front wheel steering angle compensation target is obtained.

5. The method according to claim 1, characterized in that, The step of determining the rear wheel angle compensation target within the total front wheel angle compensation target based on the physical constraints of the vehicle's rear wheel steering system, and allocating the rear wheel angle compensation target to the vehicle's rear wheel steering system to obtain rear wheel angle commands includes: The low-frequency component of the total front wheel steering angle compensation target is extracted using a low-pass filter; Based on the low-frequency component of the total front wheel steering angle compensation target, the rear wheel mechanical steering angle constraint and mechanical thrust constraint of the vehicle, the rear wheel steering angle compensation target allocated to the rear wheel steering system in the total front wheel steering angle compensation target is determined; The rear wheel angle command is determined based on the rear wheel angle compensation target and the steady-state gain relationship between the front wheel angle and the rear wheel angle on the steering motion.

6. The method according to any one of claims 1 to 5, characterized in that, The step of determining the additional yaw moment command based on the physical constraints of the vehicle's distributed drive torque vectoring system and the remaining steering angle compensation target includes: Obtain the target gain function corresponding to the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion; The original additional yaw moment command is determined by multiplying the remaining angle compensation target with the function value of the target gain function. The additional yaw moment command is determined based on the original additional yaw moment command and the yaw moment constraint corresponding to the distributed drive torque vector system.

7. The method according to claim 6, characterized in that, The step of obtaining the target gain function corresponding to the steady-state gain relationship between the front wheel steering angle and the additional yaw moment on the steering motion includes: Obtain the front axle equivalent lateral stiffness, rear axle equivalent lateral stiffness, and wheelbase of the vehicle; Based on the equivalent lateral stiffness of the front axle and the equivalent lateral stiffness of the rear axle, the overall lateral stiffness of the vehicle is determined. The target gain function is obtained based on the vehicle's lateral stiffness and the wheelbase.

8. The method according to claim 6, characterized in that, The step of determining the additional yaw moment command based on the original additional yaw moment command and the yaw moment constraint corresponding to the distributed drive torque vector system includes: If the value of the original additional yaw moment command is within the range of the yaw moment constraint, then the original additional yaw moment command is determined to be the additional yaw moment command. If the value of the original additional yaw moment command is less than or equal to the minimum value of the yaw moment constraint, then the minimum value of the yaw moment constraint is determined to be the additional yaw moment command. If the value of the original additional yaw moment command is greater than or equal to the maximum value of the yaw moment constraint, then the maximum value of the yaw moment constraint is determined to be the additional yaw moment command.

9. The method according to claim 6, characterized in that, The steps for determining the yaw moment constraint include: The number of power motors in the vehicle, the maximum allowable output torque of the power motors, and the output torque of the power motors are obtained. The maximum adhesion between the vehicle's tires and the road surface, the allocated torque corresponding to the tires, and the remaining allocateable torque corresponding to the tires are obtained. The yaw moment constraint is determined based on the number of power motors, the maximum permissible output torque, the already output torque, the maximum adhesion force, the already allocated torque, and the remaining allocateable torque.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 9.

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