Steering control method and system based on motor driving assistance and vehicle

Abstract

The invention discloses a steering control method and system based on motor driving assistance and a vehicle, and belongs to the technical field of vehicle steering control. The method comprises the steps that the vehicle speed, the front wheel turning angle and design parameters of a vehicle are obtained, and the side slip angle speed is calculated according to the vehicle speed and the design parameters of the vehicle; according to the side slip angle speed and design parameters of the vehicle, the yaw velocity is calculated; calculating a stability factor according to the yaw acceleration, the vehicle speed and the design parameters of the vehicle; determining a steering state of the vehicle based on a comparison result of the stability factor and a preset threshold; determining a motor torque distribution strategy according to the steering state; wherein according to the motor torque distribution strategy, torque difference distribution of inner and outer wheels is carried out in combination with the yawing torque requirement, and the torque of the corresponding driving motor is determined so as to adjust the turning radius. The driving safety can be improved, and the problem that correction of insufficient steering and excessive steering is difficult to conduct only through an automobile steering system in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle steering control, and particularly to a steering control method, system and vehicle based on motor drive assistance. Background Art

[0002] The statements in this part only mention the background art related to the present invention and do not necessarily constitute prior art.

[0003] The automotive steering system is an important part of a vehicle. During vehicle driving, due to various reasons, understeer or oversteer of the vehicle may occur. For example, the driver operates the steering wheel too aggressively or too cautiously during driving, or the road surface conditions are wet or uneven. If only relying on the automotive steering system for vehicle steering control, it is difficult to correct understeer and oversteer, thus affecting driving safety. Summary of the Invention

[0004] To solve the deficiencies of the prior art, the present invention provides a steering control method, device, system and vehicle based on motor drive assistance, which uses a drive motor to correct oversteer or understeer and improve driving safety.

[0005] In a first aspect, the present invention provides a steering control method based on motor drive assistance;

[0006] A steering control method based on motor drive assistance includes:

[0007] Obtain the vehicle speed, front wheel angle and design parameters of the vehicle, and calculate the centroid side slip angular velocity according to the vehicle speed and design parameters; calculate the yaw angular velocity according to the centroid side slip angular velocity and the design parameters of the vehicle;

[0008] Calculate the stability factor according to the yaw acceleration, vehicle speed and design parameters of the vehicle;

[0009] Based on the comparison result between the stability factor and a preset threshold, determine the steering state of the vehicle; according to the steering state, determine the motor torque distribution strategy; wherein, the motor torque distribution strategy combines the yaw moment demand to distribute the torque difference between the inner and outer wheels, and determines the torque of the corresponding drive motor to adjust the turning radius.

[0010] In some embodiments, the calculating the centroid side slip angular velocity according to the vehicle speed and design parameters is specifically: calculating the centroid side slip angular velocity according to the vehicle speed, front wheel angle, mass, front wheel cornering stiffness, rear wheel cornering stiffness, distance from the centroid to the front axle, and distance from the centroid to the rear axle of the vehicle.

[0011] In some embodiments, calculating the yaw rate according to the centroid sideslip angular velocity and the design parameters of the vehicle specifically includes: determining the yaw rate according to the relationship between the yaw angular acceleration, the design parameters, the yaw rate, and the front wheel steering angle.

[0012] In some embodiments, calculating the stability factor according to the yaw acceleration, vehicle speed, and design parameters of the vehicle specifically includes: calculating the stability factor according to the yaw acceleration, front wheel steering angle, vehicle speed, and wheelbase of the vehicle.

[0013] In some embodiments, determining the steering state of the vehicle based on the comparison result between the stability factor and a preset threshold specifically includes:

[0014] If the stability factor is equal to the preset threshold, the steering state is neutral steering; if the stability factor is greater than the preset threshold, the steering state is oversteering; if the stability factor is less than the preset threshold, the steering state is understeering.

[0015] In some embodiments, determining the motor torque distribution strategy according to the steering state specifically includes:

[0016] If the steering state is neutral steering, the torque is normally distributed; if the steering state is oversteering, the torque distribution to the inner wheel is increased; if the steering state is understeering, the torque distribution to the outer wheel is increased.

[0017] In some embodiments, combining the yaw moment demand to perform the torque difference distribution between the inner and outer wheels and determining the torque of the corresponding drive motor includes:

[0018] Determining the yaw moment demand according to the yaw rate and the target yaw rate;

[0019] Determining the torque difference between the left and right wheels according to the yaw moment demand, the tire rolling radius, and the track width, and calculating the corresponding torque.

[0020] In a second aspect, the present invention provides a steering control device based on motor drive assistance;

[0021] A steering control device based on motor drive assistance includes:

[0022] A steering parameter acquisition module, configured to: acquire the vehicle speed, front wheel steering angle, and design parameters of the vehicle, calculate the centroid sideslip angular velocity according to the vehicle speed and design parameters of the vehicle; calculate the yaw rate according to the centroid sideslip angular velocity and the design parameters of the vehicle;

[0023] A neutral steering value acquisition module, configured to: calculate the stability factor according to the yaw acceleration, vehicle speed, and design parameters of the vehicle;

[0024] A control module, configured to: determine the steering state of the vehicle based on the comparison result between the stability factor and a preset threshold; determine a motor torque distribution strategy according to the steering state; wherein, the motor torque distribution strategy combines the yaw moment requirement to distribute the torque difference between the inner and outer wheels, and determines the torque of the corresponding drive motor to adjust the turning radius.

[0025] In a third aspect, the present invention provides a steering control system based on motor drive assistance;

[0026] A steering control system based on motor drive assistance includes:

[0027] A domain controller, configured to obtain the vehicle speed, front wheel angle, and design parameters of the vehicle, calculate the centroid side slip angular velocity according to the vehicle speed and design parameters; calculate the yaw angular velocity according to the centroid side slip angular velocity and the design parameters of the vehicle; calculate the stability factor according to the yaw acceleration, vehicle speed, and design parameters of the vehicle; determine the steering state of the vehicle based on the comparison result between the stability factor and a preset threshold; determine a motor torque distribution strategy according to the steering state; wherein, the motor torque distribution strategy combines the yaw moment requirement to distribute the torque difference between the inner and outer wheels, and determines the torque of the corresponding drive motor to adjust the turning radius;

[0028] A drive motor, configured to rotate according to a control instruction to assist the vehicle in steering.

[0029] In a fourth aspect, the present invention provides a vehicle;

[0030] A vehicle includes the above-mentioned steering control system based on motor drive assistance.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The technical solution provided by the present invention identifies the steering state (understeer, neutral steer, oversteer) during vehicle steering. When understeer or oversteer is identified, the drive motor is controlled to redistribute the wheel torque, and on the basis of the vehicle steering system, the motor drive is coordinated to jointly correct the understeer and oversteer of the vehicle, improving driving safety. Description of the Drawings

[0033] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0034] Figure 1 It is a schematic flow chart of the steering control method based on motor drive assistance provided by an embodiment of the present invention;

[0035] Figure 2Schematic diagram of the vehicle steering state provided by the embodiment of the present invention;

[0036] Figure 3 Schematic diagram of the vehicle steering control architecture provided by the embodiment of the present invention. Detailed implementation manners

[0037] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0039] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0040] Embodiment 1

[0041] Next, in combination with Figures 1 - 3 , a steering control method based on motor drive assistance disclosed in this embodiment will be described in detail. The steering control method based on motor drive assistance includes:

[0042] S1. Obtain the vehicle speed, front wheel angle and design parameters of the vehicle, calculate the centroid side slip angular velocity according to the vehicle speed and design parameters of the vehicle; calculate the yaw angular velocity according to the centroid side slip angular velocity and the design parameters of the vehicle.

[0043] In this embodiment, the design parameters include the mass of the vehicle, the front wheel cornering stiffness, the rear wheel cornering stiffness, the distance from the centroid to the front axle, and the yaw moment of inertia, which are provided by the manufacturer before the vehicle leaves the factory.

[0044] Specifically, calculate the centroid side slip angular velocity according to the vehicle speed, front wheel angle, mass, front / rear wheel cornering stiffness, and the distance from the centroid to the front / rear axle Expressed as:

[0045]

[0046] Determine the yaw rate based on the relationship between the yaw angular acceleration, design parameters, yaw rate, and front wheel steering angle. The relationship between the yaw angular acceleration, design parameters, yaw rate, and front wheel steering angle is expressed as:

[0047]

[0048] In the formula, represents the yaw angular acceleration, represents the sideslip angular velocity of the center of mass, Ω z represents the yaw rate, β represents the sideslip angle of the center of mass, m represents the mass, v represents the vehicle speed, C f represents the front wheel sideslip stiffness, C r represents the rear wheel sideslip stiffness, a represents the distance from the center of mass to the front axle, b represents the distance from the center of mass to the rear axle, δ represents the front wheel steering angle, I z represents the yaw moment of inertia.

[0049] Substitute the known sideslip angular velocity of the center of mass, sideslip angle of the center of mass, mass, vehicle speed, front wheel sideslip stiffness, rear wheel sideslip stiffness, distance from the center of mass to the front axle, distance from the center of mass to the rear axle, front wheel steering angle, and yaw moment of inertia into the above formula to determine the yaw rate.

[0050] S2. Calculate the stability factor K based on the yaw acceleration, front wheel steering angle, vehicle speed, and wheelbase of the vehicle.

[0051] Exemplarily, the stability factor K is expressed as:

[0052]

[0053] S3. Determine the steering state based on the comparison result between the stability factor and the preset threshold.

[0054] Among them, the vehicle steering states include neutral steering, understeering, and oversteering.

[0055] In this embodiment, the preset threshold is 0; if K = 0, the steering state is neutral steering; if K > 0, the steering state is oversteering; if K < 0, the steering state is understeering.

[0056] S4. Determine the motor torque distribution strategy according to the steering state.

[0057] Specifically, as shown in the following table, if the steering state is neutral steering, the torque is normally distributed; if the steering state is oversteering, the torque distribution to the inner wheel is increased; if the steering state is understeering, the torque distribution to the outer wheel is increased.

[0058]

[0059] In this embodiment, the motor torque distribution strategy combines the yaw moment demand to distribute the torque difference between the inner and outer wheels, determines the torque of the corresponding drive motor, and adjusts the turning radius.

[0060] Further, if the steering state is oversteering, the specific process of distributing the torque difference between the inner and outer wheels in combination with the yaw moment demand and determining the torque of the corresponding drive motor is as follows:

[0061] (1) Determine the yaw moment demand M according to the yaw angular velocity, target yaw angular velocity, and longitudinal velocity Z , expressed as:

[0062]

[0063] (2) Determine the torque difference between the left and right wheels of the front axle according to the yaw moment demand, tire rolling radius, and wheelbase, and calculate the specific distribution of the corresponding torques of the front inner wheel and front outer wheel, expressed as:

[0064]

[0065] If the steering state is understeering, the specific process of distributing the torque difference between the inner and outer wheels in combination with the yaw moment demand and determining the torque of the corresponding drive motor is as follows:

[0066] (1) Determine the yaw moment demand M according to the yaw angular velocity and target yaw angular velocity Z , expressed as:

[0067]

[0068] (2) Determine the torque difference between the left and right wheels of the rear axle according to the yaw moment demand, tire rolling radius, and wheelbase, and calculate the specific distribution of the corresponding torques of the rear inner wheel and rear outer wheel, expressed as:

[0069]

[0070] In the formula, M z represents the yaw moment, K p represents the proportional gain (calibration value), K d represents the differential gain, K over represents the oversteering compensation coefficient (calibration value), ω des represents the target yaw angular velocity, ω actual represents the actual yaw angular velocity, T 后外轮 represents the torque distributed to the rear outer wheel, T 后内轮 represents the torque distributed to the rear inner wheel, T 后轴 represents the torque distributed to the rear axle, ΔT 后轴 represents the torque difference between the left and right wheels of the rear axle, T 前内轮 represents the torque distributed to the front inner wheel, T 前外轮Indicates the torque distributed to the front outer wheel, T 前轴 Indicates the torque distributed to the front axle, ΔT 前轴 Indicates the torque difference between the left and right wheels of the front axle, r represents the tire rolling radius, ω represents the track width, and β represents the vehicle sideslip angle.

[0071] Furthermore, in combination with Figure 1 , during the vehicle steering process, continuously monitor the difference between the yaw rate gain and the neutral steering value. After increasing the torque distribution of the inner / outer wheels, further calculate the difference between the yaw rate gain and the neutral steering value to avoid insufficient or excessive torque compensation and improve safety.

[0072] Specifically, when it is determined that the vehicle is understeering, after increasing the torque distribution of the outer wheel, compare the difference between the yaw rate gain and the neutral steering value again. If the difference between the yaw rate gain and the neutral steering value is equal to 0, it is determined that the torque distribution is reasonable at this time, and torque is distributed normally according to the current torque distribution strategy; if the difference between the yaw rate gain and the neutral steering value is greater than 0, it is determined that the vehicle is in an oversteering state, that is, the torque increased on the outer wheel is too much, and increase the torque distribution of the inner wheel; if the difference between the yaw rate gain and the neutral steering value is less than 0, it is determined that the vehicle is still in an understeering state, that is, the torque increased on the outer wheel is insufficient, and continue to increase the torque distribution of the outer wheel.

[0073] Similarly, when it is determined that the vehicle is oversteering, after increasing the torque distribution of the inner wheel, compare the difference between the yaw rate gain and the neutral steering value again. If the difference between the yaw rate gain and the neutral steering value is equal to 0, it is determined that the torque distribution is reasonable at this time, and torque is distributed normally according to the current torque distribution strategy; if the difference between the yaw rate gain and the neutral steering value is greater than 0, it is determined that the vehicle is in an oversteering state, that is, the torque increased on the inner wheel is insufficient, and continue to increase the torque distribution of the inner wheel; if the difference between the yaw rate gain and the neutral steering value is less than 0, it is determined that the vehicle is in an understeering state, that is, the torque increased on the inner wheel is too much, and increase the torque distribution of the outer wheel.

[0074] Embodiment 2

[0075] This embodiment discloses a steering control device based on motor drive assistance, including:

[0076] A steering parameter acquisition module, configured to: acquire the vehicle speed, front wheel angle, and design parameters of the vehicle, calculate the centroid sideslip angular velocity according to the vehicle speed and design parameters; calculate the yaw angular velocity according to the centroid sideslip angular velocity and the design parameters of the vehicle;

[0077] A neutral steering value acquisition module, configured to: calculate the stability factor according to the yaw acceleration, vehicle speed, and design parameters of the vehicle;

[0078] A control module, configured to: determine the steering state of the vehicle based on the comparison result between the stability factor and a preset threshold; determine a motor torque distribution strategy according to the steering state; wherein, the motor torque distribution strategy combines the yaw moment requirement to perform the inner and outer wheel torque difference distribution, and determines the torque of the corresponding drive motor to adjust the turning radius.

[0079] It should be noted here that the above-mentioned steering parameter acquisition module, neutral steering value acquisition module and control module correspond to the steps in the first embodiment. The examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the content disclosed in the first embodiment. It should be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0080] Embodiment Three

[0081] Based on the first embodiment, Embodiment Three of the present invention provides a steering control system based on motor drive assistance, including:

[0082] A domain controller, configured to obtain the vehicle speed, front wheel angle and design parameters of the vehicle, calculate the centroid side slip angular velocity according to the vehicle speed and design parameters; calculate the yaw angular velocity according to the centroid side slip angular velocity and the design parameters of the vehicle; calculate the stability factor according to the vehicle's yaw acceleration, vehicle speed and design parameters; determine the steering state of the vehicle based on the comparison result between the stability factor and a preset threshold; determine a motor torque distribution strategy according to the steering state; wherein, the motor torque distribution strategy combines the yaw moment requirement to perform the inner and outer wheel torque difference distribution, and determines the torque of the corresponding drive motor to adjust the turning radius;

[0083] A drive motor, configured to rotate according to a control instruction to assist the vehicle in steering.

[0084] As Figure 3 shown, the domain controller receives data from various vehicle sensors, and the processing unit inside the controller performs real-time processing and analysis to obtain the current state information of the vehicle, such as speed, direction, acceleration, wheel state, etc. Based on the data collected by the sensors and the difference between the yaw angular velocity gain and neutral steering, it is judged whether the vehicle is understeering or oversteering. The domain controller uses a preset algorithm to calculate the optimal instruction for controlling the motor, including the output torque, speed, etc. of the motor. The domain controller controls the speed of the motor by generating a PWM signal and changing the duty cycle of the PWM signal. The controller communicates with the motor through the CAN bus to ensure the accuracy and real-time performance of the signal. After receiving the control signal, the motor drives according to the control instruction to assist the vehicle in steering; at the same time, the motor feeds back its own state information (actual speed, torque, etc.) to the domain controller so that the controller can perform closed-loop control to improve the accuracy and stability of the control.

[0085] Embodiment 4

[0086] Based on Embodiment 1, Embodiment 4 of the present invention provides a vehicle, in which the steering control system based on motor drive assistance described in the above embodiment is provided. Since the steering control system based on motor drive assistance has the above technical effects, for the technical effects of the vehicle adopting the steering control system based on motor drive assistance, please refer to the above embodiment.

[0087] In the above embodiments, the descriptions of each embodiment have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A steering control method based on motor drive assistance, characterized in that: include: Obtain the vehicle speed, front wheel steering angle and design parameters, and calculate the center of mass sideslip angular velocity according to the vehicle speed and design parameters; Calculate the yaw rate based on the sideslip rate of the center of mass and the design parameters of the vehicle; Calculate the stability factor based on the vehicle's yaw acceleration, vehicle speed and design parameters; Determining a steering state of the vehicle based on a comparison of the stability factor with a preset threshold; The motor torque distribution strategy is determined according to the steering state; wherein the motor torque distribution strategy distributes the inner and outer wheel torque difference in combination with the yaw moment requirement, and determines the torque of the corresponding drive motor to adjust the turning radius.

2. The steering control method based on motor drive assistance according to claim 1, characterized in that: The method of calculating the sideslip angular velocity of the center of mass according to the vehicle speed and design parameters is specifically as follows: calculating the sideslip angular velocity of the center of mass according to the vehicle speed, front wheel turning angle, mass, front wheel sideslip stiffness, rear wheel sideslip stiffness, distance from the center of mass to the front axle, and distance from the center of mass to the rear axle.

3. The steering control method based on motor drive assistance according to claim 1, characterized in that: The calculating of the yaw rate according to the sideslip angular velocity of the center of mass and the design parameters of the vehicle is specifically as follows: determining the yaw rate according to the relationship between the yaw acceleration and the design parameters, the yaw rate and the front wheel turning angle.

4. The steering control method based on motor drive assistance according to claim 1, characterized in that: The calculating of the stability factor according to the yaw acceleration, the vehicle speed and the design parameters of the vehicle is specifically as follows: the stability factor is calculated according to the yaw acceleration, the front wheel turning angle, the vehicle speed and the wheelbase of the vehicle.

5. The steering control method based on motor drive assistance according to claim 1, characterized in that: The determination of the steering state of the vehicle based on the comparison result of the stability factor and the preset threshold value is specifically: If the stability factor is equal to the preset threshold, the steering state is neutral steering; if the stability factor is greater than the preset threshold, the steering state is oversteering; if the stability factor is less than the preset threshold, the steering state is understeering.

6. The steering control method based on motor drive assistance according to claim 1, characterized in that: The motor torque distribution strategy is determined according to the steering state as follows: If the steering state is neutral steering, the torque is distributed normally; if the steering state is oversteering, the torque distribution to the inner wheel is increased; if the steering state is understeering, the torque distribution to the outer wheel is increased.

7. The steering control method based on motor drive assistance according to claim 1, characterized in that: The step of allocating the torque difference between the inner and outer wheels in combination with the yaw moment requirement to determine the torque of the corresponding drive motor includes: Determine the yaw moment requirement according to the yaw rate, the target yaw rate and the longitudinal speed; According to the yaw moment requirement, tire rolling radius and wheelbase, the torque difference between the left and right wheels is determined and the corresponding torque is calculated.

8. A steering control device based on motor drive assistance, characterized in that: include: The steering parameter acquisition module is configured to: acquire the vehicle speed, front wheel steering angle and design parameters of the vehicle, and calculate the center of mass side slip angular velocity according to the vehicle speed and design parameters; calculate the yaw angular velocity according to the center of mass side slip angular velocity and the design parameters of the vehicle; The neutral steering value acquisition module is configured to: calculate a stability factor according to the yaw acceleration, the vehicle speed and the design parameters of the vehicle; A control module configured to: determine a steering state of the vehicle based on a comparison result of the stability factor and a preset threshold; The motor torque distribution strategy is determined according to the steering state; wherein the motor torque distribution strategy distributes the inner and outer wheel torque difference in combination with the yaw moment requirement, and determines the torque of the corresponding drive motor to adjust the turning radius.

9. A steering control system based on motor drive assistance, characterized in that: include: The domain controller is used to obtain the vehicle speed, front wheel steering angle and design parameters, and calculate the center of mass side slip angular velocity according to the vehicle speed and design parameters; Calculating the yaw rate according to the sideslip rate of the center of mass and the design parameters of the vehicle; calculating the stability factor according to the yaw acceleration, the vehicle speed and the design parameters of the vehicle; determining the steering state of the vehicle based on the comparison result of the stability factor with a preset threshold; Determine the motor torque distribution strategy according to the steering state; wherein the motor torque distribution strategy distributes the inner and outer wheel torque difference in combination with the yaw moment demand, determines the torque of the corresponding drive motor, and adjusts the turning radius; The drive motor is used to rotate according to control instructions to assist the vehicle in steering.

10. A vehicle, characterized in that: Including the steering control system based on motor drive assistance as described in claim 9.

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