Vehicle control method based on steering ratio switching, and electronic control unit and electric vehicle

Abstract

A vehicle control method based on steering ratio switching, and an electronic control unit and an electric vehicle. The vehicle control method comprises: in response to a driving mode switching instruction of a user for a vehicle, acquiring a hand wheel angle, a road wheel angle, and a steering ratio corresponding to a driving mode to be switched of the vehicle; determining whether the hand wheel angle and the road wheel angle are within a preset angle range, and when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range, determining whether the hand wheel angle of the vehicle changes; when it is determined that the hand wheel angle changes, acquiring a hand wheel angle and a road wheel angle of the vehicle at the current moment, and determining a target road wheel angle of the vehicle at the current moment on the basis of the steering ratio and the hand wheel angle of the vehicle at the current moment; and determining a target steering ratio of the vehicle on the basis of the target road wheel angle of the vehicle at the current moment and the road wheel angle of the vehicle at the current moment, and controlling the vehicle to operate at the target steering ratio. The vehicle control method can achieve seamless steering ratio switching of vehicles.

Description

Vehicle control method based on steering ratio switching, electronic control unit and electric vehicle

[0001] The present application claims priority from the Chinese patent application No. 202410464366.8 filed on April 17, 2024, and entitled "Vehicle control method based on steering ratio switching, electronic control unit and electric vehicle", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of new energy vehicles, and more particularly to a vehicle control method based on steering ratio switching, an electronic control unit and an electric vehicle. BACKGROUND

[0003] In a new energy vehicle, a steer-by-wire system can design a steering ratio of the vehicle, i.e., a ratio of a steering angle of a steering wheel to a steering angle of a wheel, according to a driving habit and a satisfaction of a driver, because the steer-by-wire system has no mechanical transmission components. Different driving modes often correspond to different steering ratios, and the steering ratio needs to be switched when the driving mode is switched.

[0004] In the prior art, when the steering wheel and the wheel are not at zero position, if the steering ratio is switched, the steering wheel and the wheel will automatically return to zero position and then the steering ratio is switched. That is, at this time, even if the driver does not turn the steering wheel, the steering wheel will automatically return to zero position, which causes the driver to feel unexpected steering wheel rotation and a poor experience. At the same time, the wheel will also automatically return to zero position, which is very dangerous for the vehicle running. SUMMARY

[0005] The present application aims to provide a vehicle control method based on steering ratio switching, an electronic control unit and an electric vehicle, to solve the problem that the driver will feel unexpected steering wheel rotation and the unexpected steering of the wheel is easy to cause danger when the driving mode is switched in the prior art.

[0006] In a first aspect, the application provides a vehicle control method based on steering ratio switching, comprising: in response to a user's driving mode switching instruction for a vehicle, acquiring a hand wheel angle of the vehicle, a road wheel angle of the vehicle, and a steering ratio corresponding to a driving mode to be switched; wherein the hand wheel angle represents an included angle between a steering angle of a steering wheel of the vehicle and a steering wheel zero position; the road wheel angle represents an included angle between a steering angle of a road wheel of the vehicle and a road wheel zero position; and the steering ratio represents a ratio of the hand wheel angle to the road wheel angle; determining whether the hand wheel angle and the road wheel angle are within a preset angle range, and when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range, determining whether the hand wheel angle of the vehicle changes; when it is determined that the hand wheel angle changes, acquiring the hand wheel angle and the road wheel angle of the vehicle at a current time, and determining a target road wheel angle of the vehicle at the current time according to the steering ratio and the hand wheel angle of the vehicle at the current time; and determining a target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and controlling the vehicle to operate at the target steering ratio.

[0007] In a specific embodiment, determining the target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time comprises: when it is determined that the target road wheel angle of the vehicle at the current time is equal to the road wheel angle of the vehicle at the current time, determining that the steering ratio corresponding to the driving mode to be switched is the target steering ratio of the vehicle.

[0008] In a specific embodiment, determining the target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time comprises: when it is determined that the target road wheel angle of the vehicle at the current time is not equal to the road wheel angle of the vehicle at the current time, determining that the steering ratio corresponding to the current driving mode is the target steering ratio of the vehicle.

[0009] In one specific implementation, after the vehicle is controlled to operate at the target steering ratio, the method further comprises: when the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode, obtaining a first difference value between the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time; the first difference value represents an absolute value of a difference between the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time; obtaining a hand wheel angle of the vehicle at a next time, and determining a target road wheel angle of the vehicle at the next time according to the steering ratio corresponding to the to-be-switched driving mode and the hand wheel angle of the vehicle at the next time; obtaining a second difference value between the target road wheel angle of the vehicle at the next time and the road wheel angle of the vehicle at the current time; the second difference value represents an absolute value of a difference between the target road wheel angle of the vehicle at the next time and the road wheel angle of the vehicle at the current time; when it is determined that the second difference value is greater than the first difference value, the vehicle is controlled to operate at the steering ratio corresponding to the to-be-switched driving mode.

[0010] In one specific implementation, the method further comprises: when it is determined that the second difference value is less than the first difference value, every preset time, obtaining a current hand wheel angle of the vehicle, and determining a current target road wheel angle of the vehicle according to the steering ratio corresponding to the to-be-switched driving mode and the current hand wheel angle of the vehicle; when it is determined that the current target road wheel angle of the vehicle is equal to the road wheel angle of the vehicle at the current time, the vehicle is controlled to operate at the steering ratio corresponding to the to-be-switched driving mode.

[0011] In one specific implementation, the method further comprises: when it is determined that the hand wheel angle and the road wheel angle are not within a preset angle range, the vehicle is controlled to operate at the steering ratio corresponding to the current driving mode.

[0012] In one specific implementation, the method further comprises: when it is determined that the hand wheel angle has not changed, the vehicle is controlled to operate at the steering ratio corresponding to the current driving mode.

[0013] In a second aspect, the application provides an electronic control unit, comprising: an acquisition module configured to acquire a hand wheel angle, a road wheel angle and a target steering ratio corresponding to a driving mode to be switched of a vehicle in response to a driving mode switching instruction of the vehicle; wherein the hand wheel angle represents an included angle between a steering angle of a steering wheel of the vehicle and a zero position of the steering wheel; the road wheel angle represents an included angle between a steering angle of a wheel of the vehicle and a zero position of the wheel; and the target steering ratio represents a ratio of the hand wheel angle to the road wheel angle; and a processing module configured to determine whether the hand wheel angle and the road wheel angle are within a preset angle range, and determine whether the hand wheel angle of the vehicle changes when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range; the processing module is further configured to acquire the hand wheel angle and the road wheel angle of the vehicle at a current time when it is determined that the hand wheel angle changes, and determine a target road wheel angle of the vehicle at the current time according to the target steering ratio and the hand wheel angle of the vehicle at the current time; and the processing module is further configured to determine a target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and control the vehicle to operate at the target steering ratio.

[0014] In a third aspect, the application provides an electronic control unit, comprising: a processor, a memory and a communication interface; the memory is configured to store executable instructions of the processor; wherein the processor is configured to execute the vehicle control method based on the steering ratio switching according to the first aspect by executing the executable instructions.

[0015] In a fourth aspect, the application provides an electric vehicle, comprising: the electronic control unit according to the second aspect or the third aspect.

[0016] The application provides a vehicle control method based on steering ratio switching, an electronic control unit and an electric vehicle. The method comprises the following steps: in response to a driving mode switching instruction of a user for a vehicle, acquiring a hand wheel angle, a road wheel angle and a steering ratio corresponding to a to-be-switched driving mode of the vehicle; determining whether the hand wheel angle and the road wheel angle are within a preset angle range, and when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range, determining whether the hand wheel angle of the vehicle changes; when it is determined that the hand wheel angle changes, acquiring the hand wheel angle and the road wheel angle of the vehicle at a current time, and determining a target road wheel angle of the vehicle at the current time according to the steering ratio and the hand wheel angle of the vehicle at the current time; and determining a target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and controlling the vehicle to operate at the target steering ratio. Compared with the prior art, the vehicle control method based on steering ratio switching can determine the target steering ratio of the vehicle according to the hand wheel angle of the vehicle at the current time, the road wheel angle and the steering ratio corresponding to the to-be-switched mode when the hand wheel angle and the road wheel angle are within the preset angle range and the hand wheel angle changes, and control the vehicle to operate at the target steering ratio. The vehicle steering ratio can be switched without feeling when the steering wheel and the road wheel are both near zero and the driver controls the steering wheel to turn, the driver can avoid feeling unexpected steering wheel rotation and unexpected road wheel turning, and the problem that the driver feels unexpected steering wheel rotation and unexpected road wheel turning when the driving mode is switched in the prior art can be solved. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0018] Fig. 1 is a structural schematic diagram of a steer-by-wire system of an electric vehicle;

[0019] Fig. 2 is a flow schematic diagram of a vehicle control method based on steering ratio switching according to an embodiment of the application;

[0020] Fig. 3 is a flow schematic diagram of a vehicle control method based on steering ratio switching according to another embodiment of the application;

[0021] Fig. 4 is a flow schematic diagram of a vehicle control method based on steering ratio switching according to another embodiment of the application;

[0022] Fig. 5 is a structural schematic diagram of an electronic control unit according to an embodiment of the application;

[0023] Fig. 6 is a structural schematic diagram of another electronic control unit according to an embodiment of the application.

[0024] The present application has been shown and described with reference to the preferred embodiments. Equivalent mechanisms of the application in alternative embodiments can be constructed without departing from the scope of the application, therefore the full scope of the application is determined by the appended claims rather than the examples given. DETAILED DESCRIPTION

[0025] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description of the exemplary embodiments is intended to apply to various alternative embodiments as well. It is to be understood that features illustrated or described as part of one embodiment can be provided with one or more of the other embodiments as well. Variations to these embodiments can become apparent to those of ordinary skill in the art once the concepts have been fully appreciated. The following detailed description is not intended to limit the applications to only the described and illustrated embodiments. Alternate embodiments

[0026] In a new energy vehicle, a steer-by-wire system can design a steering ratio of the vehicle according to driving habits and satisfaction of a driver, i.e., a ratio of a steering angle of a steering wheel to a steering angle of a wheel, because the steer-by-wire system has no mechanical transmission components. Different driving modes often correspond to different steering ratios, and the steering ratio needs to be switched when the driving mode is switched.

[0027] FIG. 1 is a structural schematic diagram of a steer-by-wire system of an electric vehicle. As shown in FIG. 1, the steer-by-wire system includes a steering wheel, a steer-by-wire hand wheel (HWA) connected to the steering wheel, a wheel, and a road wheel actuator (RWA) connected to the wheel. The steer-by-wire hand wheel HWA includes an electric steering column connected to the steering wheel, a torque angle sensor (TAS), a reduction mechanism, a motor, and an electronic control unit (ECU). The road wheel actuator RWA includes a rack displacement sensor, a torque angle sensor TAS, a reduction mechanism, a motor, an electronic control unit ECU, and an electric power steering dual pinion (EPSdp) or a reinforced electric power steering (REPS). The ECU in the steer-by-wire hand wheel HWA and the ECU in the road wheel actuator RWA are connected through a CAN bus.

[0028] The ECU in the steer-by-wire hand wheel HWA acquires the steering angle of the steering wheel, calculates the target steering angle of the wheel according to the steering ratio, and sends the target steering angle to the ECU in the road wheel executing motor RWA, so that the road wheel executing motor RWA controls the wheel to steer at the target steering angle.

[0029] In the prior art, when the angles of the steering wheel and the wheel are not at zero, if the steering ratio is switched, the steering wheel and the wheel will automatically return to zero and then switch the steering ratio. That is, at this time, even if the driver does not turn the steering wheel, the steering wheel will automatically return to zero, causing the driver to feel unexpected steering wheel rotation, which is not good experience. At the same time, the wheel will also automatically return to zero, which is very dangerous for the vehicle in motion.

[0030] Based on the above technical problems, the technical concept of the present application is as follows: how to provide a vehicle control method based on steering ratio switching, which can realize the in-sensitive switching of the steering ratio of the vehicle, and avoid the driver feeling unexpected steering wheel rotation and the unexpected steering of the wheel.

[0031] The vehicle control method based on steering ratio switching provided by the present application aims to solve the above technical problems of the prior art.

[0032] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0033] Fig. 2 is a flowchart of an embodiment of a vehicle control method based on steering ratio switching provided by the present application. Referring to Fig. 2, the vehicle control method based on steering ratio switching can be executed by an electronic control unit, and specifically includes the following steps:

[0034] Step S201: In response to a user's driving mode switching instruction for a vehicle, acquiring a hand wheel angle, a road wheel angle and a steering ratio corresponding to a to-be-switched driving mode of the vehicle.

[0035] The hand wheel angle represents the included angle between the steering angle of the steering wheel of the vehicle and the zero position of the steering wheel; the road wheel angle represents the included angle between the steering angle of the wheel of the vehicle and the zero position of the wheel; and the steering ratio represents the ratio of the hand wheel angle to the road wheel angle.

[0036] In the embodiment, the driving modes of the vehicle can include a comfort mode, a sport mode, etc. When the driving mode is switched, the steering ratio is often switched. The steering ratio is the ratio of the steering wheel angle to the road wheel angle, and corresponds to the driving mode: in the comfort mode, the vehicle usually needs a larger steering ratio to provide better steering stability; in the sport mode, the vehicle usually needs a smaller steering ratio to provide higher steering sensitivity.

[0037] The electronic control unit can obtain the steering wheel angle, the road wheel angle and the steering ratio corresponding to the driving mode to be switched in response to the user's driving mode switching instruction of the vehicle. The steering wheel angle of the vehicle is the included angle between the steering angle of the steering wheel of the vehicle and the zero position of the steering wheel; the road wheel angle is the included angle between the steering angle of the vehicle wheel and the zero position of the vehicle wheel.

[0038] Step S202: Determine whether the steering wheel angle and the road wheel angle are within a preset angle range, and determine whether the steering wheel angle of the vehicle changes when it is determined that the steering wheel angle and the road wheel angle are within the preset angle range.

[0039] In the embodiment, the electronic control unit can determine whether the steering wheel angle and the road wheel angle are within a preset angle range. Exemplarily, the preset angle range can be ±2 degrees. The steering wheel angle and the road wheel angle are both within the preset angle range, indicating that the steering wheel and the road wheel are both rotated to a state close to the zero position.

[0040] When it is determined that the steering wheel angle and the road wheel angle are within the preset angle range, it can be further determined whether the steering wheel angle of the vehicle changes. Whether the steering wheel angle changes represents whether the driver actively controls the rotation of the steering wheel and intends to steer.

[0041] Step S203: When it is determined that the steering wheel angle changes, obtain the steering wheel angle and the road wheel angle of the vehicle at the current time, and determine the target road wheel angle of the vehicle at the current time according to the steering ratio and the steering wheel angle of the vehicle at the current time.

[0042] In the embodiment, the electronic control unit can obtain the steering wheel angle and the road wheel angle of the vehicle at the current time when it is determined that the steering wheel angle changes, i.e., the driver actively controls the rotation of the steering wheel.

[0043] According to the steering ratio corresponding to the driving mode to be switched and the steering wheel angle of the vehicle at the current time, the target road wheel angle of the vehicle at the current time can be determined. Exemplarily, the target road wheel angle of the vehicle at the current time can be obtained by using the formula: target road wheel angle = steering wheel angle / steering ratio. For example, the steering ratio corresponding to the driving mode to be switched is 2 to 1, and the steering wheel angle of the vehicle at the current time is 120 degrees, then the target road wheel angle of the vehicle at the current time is 60 degrees.

[0044] Step S204: determining the target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and controlling the vehicle to run at the target steering ratio.

[0045] In the embodiment, the electronic control unit can determine the target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time.

[0046] In a possible implementation, the target steering ratio corresponding to the to-be-switched driving mode can be determined as the target steering ratio of the vehicle when it is determined that the target road wheel angle of the vehicle at the current time is equal to the road wheel angle of the vehicle at the current time, and the steering ratio of the vehicle is switched.

[0047] In a possible implementation, the target steering ratio corresponding to the to-be-switched driving mode can be determined as the target steering ratio of the vehicle when it is determined that the target road wheel angle of the vehicle at the current time is equal to the road wheel angle of the vehicle at the current time, and the steering ratio of the vehicle is switched.

[0048] As described in the foregoing example, the target road wheel angle of the vehicle at the current time is 60 degrees, if the road wheel angle of the vehicle at the current time is also 60 degrees, which is consistent with the target road wheel angle of the vehicle at the current time, the steering ratio of the vehicle can be switched according to the target steering ratio corresponding to the to-be-switched driving mode, so as to realize the seamless switching of the steering ratio of the vehicle; if the road wheel angle of the vehicle at the current time is not 60 degrees, in order to avoid the switching of the steering ratio causing the dangerous wheel unintended steering, the current steering ratio of the vehicle is maintained, and the switching of the steering ratio is not performed.

[0049] In this embodiment, in response to a user's driving mode switching instruction for a vehicle, the hand wheel angle, the road wheel angle and the steering ratio corresponding to the driving mode to be switched of the vehicle are obtained; it is determined whether the hand wheel angle and the road wheel angle are within a preset angle range, and when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range, it is determined whether the hand wheel angle of the vehicle changes; when it is determined that the hand wheel angle changes, the hand wheel angle and the road wheel angle of the vehicle at the current time are obtained, and the target road wheel angle of the vehicle at the current time is determined according to the steering ratio and the hand wheel angle of the vehicle at the current time; the target steering ratio of the vehicle is determined according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and the vehicle is controlled to run at the target steering ratio. Compared with the prior art, the vehicle control method based on steering ratio switching can determine the target steering ratio of the vehicle according to the hand wheel angle of the vehicle at the current time, the road wheel angle and the steering ratio corresponding to the mode to be switched when the hand wheel angle and the road wheel angle are within the preset angle range and the hand wheel angle changes, and control the vehicle to run at the target steering ratio. When the steering wheel and the wheels are both near zero and the driver controls the steering wheel to turn, the vehicle steering ratio can be switched without feeling, avoiding the driver feeling unexpected steering wheel rotation and unexpected wheel turning, and solving the problem that the driver feels unexpected steering wheel rotation and unexpected wheel turning when the driving mode is switched in the prior art, which easily leads to danger.

[0050] FIG. 3 is a flow diagram of an embodiment two of the vehicle control method based on steering ratio switching provided by the present application. Referring to FIG. 3, after the step S204, the vehicle control method based on steering ratio switching further includes the following steps:

[0051] Step S301: When the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode, a first difference value between the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time is obtained.

[0052] The first difference value represents the absolute value of the difference between the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time.

[0053] In this embodiment, after the electronic control unit controls the vehicle to run at the target steering ratio, it is determined whether the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode. When it is determined that the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode, i.e., the vehicle does not perform steering ratio switching, a first difference value between the target road wheel angle c of the vehicle at the current time and the road wheel angle b of the vehicle at the current time is obtained, and the first difference value is the absolute value |c-b| of the difference between the target road wheel angle c of the vehicle at the current time and the road wheel angle b of the vehicle at the current time.

[0054] Step S302: Obtain the hand wheel angle of the vehicle at the next time, and determine the target road wheel angle of the vehicle at the next time according to the steering ratio corresponding to the to-be-switched driving mode and the hand wheel angle of the vehicle at the next time.

[0055] In this embodiment, the electronic control unit can further obtain the hand wheel angle of the vehicle at the next time, and determine the target road wheel angle c' of the vehicle at the next time according to the steering ratio corresponding to the to-be-switched driving mode and the hand wheel angle of the vehicle at the next time. The target road wheel angle c' of the vehicle at the next time can be obtained by using the formula: target road wheel angle = hand wheel angle / steering ratio.

[0056] Step S303: Obtain the second difference value between the target road wheel angle of the vehicle at the next time and the road wheel angle of the vehicle at the current time.

[0057] The second difference value represents the absolute value of the difference between the target road wheel angle of the vehicle at the next time and the road wheel angle of the vehicle at the current time.

[0058] In this embodiment, the electronic control unit can further obtain the second difference value between the target road wheel angle c' of the vehicle at the next time and the road wheel angle b of the vehicle at the current time, and the second difference value is the absolute value |c'-b| of the difference between the target road wheel angle c' of the vehicle at the next time and the road wheel angle b of the vehicle at the current time.

[0059] Step S304: Determine whether the second difference value is greater than the first difference value; if yes, execute step S305; if no, execute step S306.

[0060] Step S305: When it is determined that the second difference value is greater than the first difference value, control the vehicle to operate at the steering ratio corresponding to the to-be-switched driving mode.

[0061] In this embodiment, if the second difference value is greater than the first difference value, it indicates that the difference between the target road wheel angle of the vehicle and the road wheel angle of the vehicle at the current time is getting larger and larger with the rotation of the steering wheel. For example, the target road wheel angle c of the vehicle at the current time is -1 degree, the road wheel angle b of the vehicle at the current time is 1 degree, the first difference value |c-b| is 2 degrees; the target road wheel angle c' of the vehicle at the next time is -2 degrees, the second difference value |c'-b| is 3 degrees, and the difference between the target road wheel angle of the vehicle and the road wheel angle of the vehicle at the current time is getting larger and larger. At this time, the steering ratio should be switched to the steering ratio corresponding to the to-be-switched driving mode in time to avoid that the non-expected steering of the vehicle wheel is too large due to the non-timely switching of the steering ratio, or even opposite to the steering of the steering wheel.

[0062] Step S306: When it is determined that the second difference value is less than the first difference value, every preset time, the current hand wheel angle of the vehicle is obtained, and the current target road wheel angle of the vehicle is determined according to the target steering ratio corresponding to the to-be-switched driving mode and the current hand wheel angle of the vehicle.

[0063] Step S307: When it is determined that the current target road wheel angle of the vehicle is equal to the road wheel angle of the vehicle at the current time, the vehicle is controlled to run at the target steering ratio corresponding to the to-be-switched driving mode.

[0064] In this embodiment, if the second difference value is less than the first difference value, it indicates that the difference between the target road wheel angle of the vehicle and the road wheel angle of the vehicle at the current time is getting smaller and smaller as the steering wheel rotates. For example, the target road wheel angle c of the vehicle at the current time is -2 degrees, the road wheel angle b of the vehicle at the current time is 1 degree, the first difference value |c-b| is 3 degrees; the target road wheel angle c' of the vehicle at the next time is -1 degree, the second difference value |c'-b| is 2 degrees, and the difference between the target road wheel angle of the vehicle and the road wheel angle of the vehicle at the current time is getting smaller and smaller. At this time, the steering ratio can be switched to the target steering ratio corresponding to the to-be-switched driving mode when the target road wheel angle of the vehicle is equal to the road wheel angle b of the vehicle at the current time, so as to realize the seamless switching of the steering ratio of the vehicle.

[0065] Specifically, the target road wheel angle of the vehicle can be determined periodically: every preset time, the current hand wheel angle of the vehicle can be obtained, and the current target road wheel angle of the vehicle can be determined according to the target steering ratio corresponding to the to-be-switched driving mode and the current hand wheel angle of the vehicle. When it is determined that the current target road wheel angle of the vehicle is equal to the road wheel angle of the vehicle at the current time, the vehicle is controlled to run at the target steering ratio corresponding to the to-be-switched driving mode.

[0066] In this embodiment, when the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode, whether to switch the steering ratio to the target steering ratio corresponding to the to-be-switched driving mode can be determined according to the difference between the target road wheel angle of the vehicle at different times and the road wheel angle of the vehicle at the current time. In this way, when the difference between the target road wheel angle of the vehicle and the road wheel angle of the vehicle at the current time is getting larger and larger, the steering ratio can be switched in time to avoid the non-expected steering of the wheels caused by the non-expected steering of the steering wheel due to the non-expected steering ratio switching; when the difference between the target road wheel angle of the vehicle and the road wheel angle of the vehicle at the current time is getting smaller and smaller, the steering ratio is switched to the target steering ratio corresponding to the to-be-switched driving mode when they are equal, so as to realize the seamless switching of the steering ratio of the vehicle. Further, the problem that the driver feels the non-expected steering of the steering wheel and the non-expected steering of the wheels easily leads to danger during the driving mode switching in the prior art is solved.

[0067] FIG. 4 is a flowchart of an embodiment three of a vehicle control method based on steering ratio switching provided by the present application. Referring to FIG. 4, the vehicle control method based on steering ratio switching can be executed by an electronic control unit, and specifically includes the following steps:

[0068] Step S401: In response to a user's driving mode switching instruction for a vehicle, the hand wheel angle, road wheel angle, and steering ratio corresponding to the driving mode to be switched of the vehicle are obtained.

[0069] The hand wheel angle represents the included angle between the steering angle of the steering wheel of the vehicle and the zero position of the steering wheel; the road wheel angle represents the included angle between the steering angle of the wheel of the vehicle and the zero position of the wheel; and the steering ratio represents the ratio of the hand wheel angle to the road wheel angle.

[0070] In this embodiment, the electronic control unit can obtain the hand wheel angle, road wheel angle, and steering ratio corresponding to the driving mode to be switched of the vehicle in response to a user's driving mode switching instruction for the vehicle. The hand wheel angle of the vehicle is the included angle between the steering angle of the steering wheel of the vehicle and the zero position of the steering wheel; and the road wheel angle is the included angle between the steering angle of the wheel of the vehicle and the zero position of the wheel.

[0071] Step S402: It is determined whether the hand wheel angle and the road wheel angle are within a preset angle range; if not, step S403 is executed; and if yes, step S404 is executed.

[0072] Step S403: The vehicle is controlled to run at the steering ratio corresponding to the current driving mode.

[0073] In this embodiment, the electronic control unit can determine whether the hand wheel angle and the road wheel angle are within a preset angle range. Exemplarily, the preset angle range can be ±2 degrees.

[0074] The hand wheel angle and the road wheel angle not being within the preset angle range indicates that the vehicle can be turning, and thus the vehicle is controlled to run at the steering ratio corresponding to the current driving mode, without switching the steering ratio, to avoid unintended turning of the wheel.

[0075] The hand wheel angle and the road wheel angle both being within the preset angle range indicates that the steering wheel and the wheel are both turned to a state close to the zero position. At this time, it can be further determined whether the hand wheel angle of the vehicle has changed. Whether the hand wheel angle has changed indicates whether the driver has actively controlled the turning of the steering wheel and intended to turn.

[0076] Step S404: When it is determined that the hand wheel angle and the road wheel angle are within the preset angle range, it is determined whether the hand wheel angle of the vehicle has changed. If yes, step S405 is executed; and if not, step S403 is executed.

[0077] Step S405: Obtain the hand wheel angle and the road wheel angle of the vehicle at the current time, and determine the target road wheel angle of the vehicle at the current time according to the steering ratio and the hand wheel angle of the vehicle at the current time.

[0078] In this embodiment, the electronic control unit can determine whether the hand wheel angle of the vehicle changes when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range.

[0079] When it is determined that the hand wheel angle does not change, i.e., the driver does not actively control the rotation of the steering wheel, the vehicle is controlled to operate at the steering ratio corresponding to the current driving mode, and the steering ratio is not switched, thereby avoiding unintended steering of the wheels.

[0080] When it is determined that the hand wheel angle changes, i.e., the driver actively controls the rotation of the steering wheel, the hand wheel angle and the road wheel angle of the vehicle at the current time are obtained. According to the steering ratio corresponding to the driving mode to be switched and the hand wheel angle of the vehicle at the current time, the target road wheel angle of the vehicle at the current time can be determined.

[0081] Step S406: Determine whether the target road wheel angle of the vehicle at the current time is equal to the road wheel angle of the vehicle at the current time; if yes, execute step S407; if no, execute step S408.

[0082] Step S407: Determine that the steering ratio corresponding to the driving mode to be switched is the target steering ratio of the vehicle, and control the vehicle to operate at the target steering ratio.

[0083] Step S408: Determine that the steering ratio corresponding to the current driving mode is the target steering ratio of the vehicle, and control the vehicle to operate at the target steering ratio.

[0084] In this embodiment, when it is determined that the target road wheel angle of the vehicle at the current time is equal to the road wheel angle of the vehicle at the current time, the steering ratio of the vehicle can be switched according to the steering ratio corresponding to the driving mode to be switched, thereby achieving the inapparent switching of the steering ratio of the vehicle.

[0085] When it is determined that the target road wheel angle of the vehicle at the current time is not equal to the road wheel angle of the vehicle at the current time, in order to avoid the danger caused by unintended steering of the wheels due to switching of the steering ratio, the current steering ratio of the vehicle is maintained, and the steering ratio is not switched.

[0086] In the embodiment, when it is determined that the hand wheel angle and the road wheel angle are not within the preset angle range, i.e., the vehicle is steering, the vehicle is controlled to operate at a steering ratio corresponding to the current driving mode, effectively avoiding the risk caused by the unintended steering of the vehicle wheels during the steering of the vehicle; when it is determined that the hand wheel angle does not change, i.e., the driver does not actively control the rotation of the steering wheel, the vehicle is controlled to operate at the steering ratio corresponding to the current driving mode, without switching the steering ratio, effectively avoiding the risk caused by the unintended steering of the vehicle wheels when the driver does not control the steering wheel. Further, the problem that the driver feels the unintended rotation of the steering wheel and the unintended steering of the vehicle wheels during the driving mode switching in the prior art is solved.

[0087] The following is an apparatus embodiment of the present application, which can be used to execute the method embodiments of the present application. For details not disclosed in the apparatus embodiments of the present application, refer to the method embodiments of the present application.

[0088] FIG. 5 is a structural schematic diagram of an electronic control unit embodiment provided by the present application. As shown in FIG. 5, the electronic control unit 50 comprises an acquisition module 51 and a processing module 52. The acquisition module 51 is configured to acquire a hand wheel angle, a road wheel angle and a steering ratio corresponding to a to-be-switched driving mode of a vehicle in response to a driving mode switching instruction of the vehicle. The hand wheel angle represents an included angle between a steering angle of a steering wheel of the vehicle and a steering wheel zero position. The road wheel angle represents an included angle between a steering angle of a wheel of the vehicle and a wheel zero position. The steering ratio represents a ratio of the hand wheel angle to the road wheel angle. The processing module 52 is configured to determine whether the hand wheel angle and the road wheel angle are within a preset angle range, and determine whether the hand wheel angle of the vehicle changes when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range. The processing module 52 is further configured to acquire the hand wheel angle and the road wheel angle of the vehicle at a current time, and determine a target road wheel angle of the vehicle at the current time according to the steering ratio and the hand wheel angle of the vehicle at the current time when it is determined that the hand wheel angle changes. The processing module 52 is further configured to determine a target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and control the vehicle to operate at the target steering ratio.

[0089] The electronic control unit provided by the embodiments of the present application can execute the technical solutions shown in the above method embodiments, and the implementation principles and beneficial effects are similar, which will not be described here in detail.

[0090] In a possible implementation, the processing module 52 is specifically configured to determine that the steering ratio corresponding to the to-be-switched driving mode is the target steering ratio of the vehicle when it is determined that the target road wheel angle of the vehicle at the current time is equal to the road wheel angle of the vehicle at the current time.

[0091] In a possible implementation, the processing module 52 is specifically configured to determine that the target steering ratio corresponding to the current driving mode is the target steering ratio of the vehicle when it is determined that the target road wheel angle of the vehicle at the current time instant is not equal to the road wheel angle of the vehicle at the current time instant.

[0092] The electronic control unit provided in the embodiments of the present application implements the technical solutions shown in the above method embodiments, and has similar implementation principles and beneficial effects, which will not be repeated here.

[0093] In a possible implementation, the processing module 52 is further configured to, after controlling the vehicle to operate at the target steering ratio, obtain a first difference value between the target road wheel angle of the vehicle at the current time instant and the road wheel angle of the vehicle at the current time instant when the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode; the first difference value represents an absolute value of a difference between the target road wheel angle of the vehicle at the current time instant and the road wheel angle of the vehicle at the current time instant; obtain a hand wheel angle of the vehicle at a next time instant, and determine a target road wheel angle of the vehicle at the next time instant according to the steering ratio corresponding to the to-be-switched driving mode and the hand wheel angle of the vehicle at the next time instant; obtain a second difference value between the target road wheel angle of the vehicle at the next time instant and the road wheel angle of the vehicle at the current time instant; the second difference value represents an absolute value of a difference between the target road wheel angle of the vehicle at the next time instant and the road wheel angle of the vehicle at the current time instant; and control the vehicle to operate at the steering ratio corresponding to the to-be-switched driving mode when it is determined that the second difference value is greater than the first difference value.

[0094] In a possible implementation, the processing module 52 is further configured to, when it is determined that the second difference value is less than the first difference value, obtain a current hand wheel angle of the vehicle every preset time, and determine a current target road wheel angle of the vehicle according to the steering ratio corresponding to the to-be-switched driving mode and the current hand wheel angle of the vehicle; and control the vehicle to operate at the steering ratio corresponding to the to-be-switched driving mode when it is determined that the current target road wheel angle of the vehicle is equal to the road wheel angle of the vehicle at the current time instant.

[0095] The electronic control unit provided in the embodiments of the present application implements the technical solutions shown in the above method embodiments, and has similar implementation principles and beneficial effects, which will not be repeated here.

[0096] In a possible implementation, the processing module 52 is further configured to control the vehicle to operate at the steering ratio corresponding to the current driving mode when it is determined that the hand wheel angle and the road wheel angle are not within a preset angle range.

[0097] In a possible implementation, the processing module 52 is further configured to control the vehicle to operate at the steering ratio corresponding to the current driving mode when it is determined that the hand wheel angle has not changed.

[0098] The electronic control unit provided by the embodiments of the present application can execute the technical solutions shown in the method embodiments, and the implementation principles and beneficial effects are similar, which will not be repeated here.

[0099] FIG. 6 is a structural schematic diagram of another embodiment of the electronic control unit provided by the present application. As shown in FIG. 6, the electronic control unit 60 includes a processor 61, a memory 62, and a communication interface 63; the memory 62 is configured to store executable instructions of the processor 61; and the processor 61 is configured to execute the technical solutions in any of the preceding method embodiments by executing the executable instructions.

[0100] Optionally, the memory 62 can be independent or integrated with the processor 61.

[0101] Optionally, when the memory 62 is independent of the processor 61, the electronic control unit 60 can further include a bus 64 for connecting the above-mentioned devices.

[0102] The electronic control unit is configured to execute the technical solutions in any of the preceding method embodiments, and the implementation principles and technical effects are similar, which will not be repeated here.

[0103] The embodiments of the present application further provide an electric vehicle including the electronic control unit provided by any of the preceding embodiments.

[0104] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are considered exemplary only, and the true scope and spirit of the application is indicated by the following claims. The application is not limited to the exact details shown and described herein.

[0105] It should be understood that the present application is not limited to the precise construction that has been described and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application should be limited only by the appended claims.

Claims

1. A vehicle control method based on steering ratio switching, characterized by, The method comprises: in response to a user's driving mode switching instruction for a vehicle, acquiring a hand wheel angle of the vehicle, a road wheel angle of the vehicle, and a steering ratio corresponding to a to-be-switched driving mode; wherein the hand wheel angle represents an included angle between a steering angle of a steering wheel of the vehicle and a steering wheel zero position; the road wheel angle represents an included angle between a steering angle of a wheel of the vehicle and a wheel zero position; and the steering ratio represents a ratio of the hand wheel angle to the road wheel angle; determining whether the hand wheel angle and the road wheel angle are within a preset angle range, and when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range, determining whether the hand wheel angle of the vehicle changes; when it is determined that the hand wheel angle changes, acquiring the hand wheel angle and the road wheel angle of the vehicle at a current time, and determining a target road wheel angle of the vehicle at the current time according to the steering ratio and the hand wheel angle of the vehicle at the current time; determining a target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and controlling the vehicle to operate at the target steering ratio.

2. The vehicle control method based on steering ratio switching according to claim 1, characterized by, The method further comprises: when it is determined that the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time are equal, determining that the steering ratio corresponding to the to-be-switched driving mode is the target steering ratio of the vehicle.

3. The steering ratio switching-based vehicle control method according to any one of claims 1 to 2, characterized by, The method further comprises: when it is determined that the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time are not equal, determining that the steering ratio corresponding to the current driving mode is the target steering ratio of the vehicle.

4. The vehicle control method based on steering ratio switching according to claim 3, characterized by, After controlling the vehicle to operate at the target steering ratio, the method further comprises: when the target steering ratio of the vehicle is the steering ratio corresponding to the current driving mode, acquiring a first difference value of the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time; the first difference value represents an absolute value of a difference between the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time; acquiring a hand wheel angle of the vehicle at a next time, and determining a target road wheel angle of the vehicle at the next time according to the steering ratio corresponding to the to-be-switched driving mode and the hand wheel angle of the vehicle at the next time; acquiring a second difference value of the target road wheel angle of the vehicle at the next time and the road wheel angle of the vehicle at the current time; the second difference value represents an absolute value of a difference between the target road wheel angle of the vehicle at the next time and the road wheel angle of the vehicle at the current time; when it is determined that the second difference value is greater than the first difference value, controlling the vehicle to operate at the steering ratio corresponding to the to-be-switched driving mode.

5. The steering ratio switching-based vehicle control method according to claim 4, characterized by The method further comprises: determining that the second difference is less than the first difference, acquiring a current hand wheel angle of the vehicle every preset time, and determining a current target road wheel angle of the vehicle according to the steering ratio corresponding to the to-be-switched driving mode and the current hand wheel angle of the vehicle; determining that the current target road wheel angle of the vehicle is equal to the road wheel angle of the vehicle at the current time, and controlling the vehicle to run at the steering ratio corresponding to the to-be-switched driving mode.

6. The steering ratio switching-based vehicle control method according to any one of claims 1 to 5, characterized by, The method further includes: determining that the hand wheel angle and the road wheel angle are not within the preset angle range, and controlling the vehicle to run at the steering ratio corresponding to the current driving mode.

7. The steering ratio switching-based vehicle control method according to any one of claims 1 to 6, characterized by, The method further includes: determining that the hand wheel angle has not changed, and controlling the vehicle to run at the steering ratio corresponding to the current driving mode.

8. An electronic control unit, characterized by comprising: an acquisition module, configured to acquire a hand wheel angle, a road wheel angle, and a steering ratio corresponding to a to-be-switched driving mode of a vehicle in response to a driving mode switching instruction of the vehicle; wherein the hand wheel angle represents an included angle between a steering angle of a steering wheel of the vehicle and a steering wheel zero position; the road wheel angle represents an included angle between a steering angle of a wheel of the vehicle and a wheel zero position; and the steering ratio represents a ratio of the hand wheel angle to the road wheel angle; a processing module, configured to determine whether the hand wheel angle and the road wheel angle are within a preset angle range, and determine whether the hand wheel angle of the vehicle has changed when it is determined that the hand wheel angle and the road wheel angle are within the preset angle range; the processing module is further configured to acquire a hand wheel angle and a road wheel angle of the vehicle at a current time when it is determined that the hand wheel angle has changed, and determine a target road wheel angle of the vehicle at the current time according to the steering ratio and the hand wheel angle of the vehicle at the current time; the processing module is further configured to determine a target steering ratio of the vehicle according to the target road wheel angle of the vehicle at the current time and the road wheel angle of the vehicle at the current time, and control the vehicle to run at the target steering ratio.

9. An electronic control unit, characterized by comprising: a processor, a memory, and a communication interface; the memory is configured to store executable instructions of the processor; wherein the processor is configured to execute the vehicle control method based on steering ratio switching according to any one of claims 1 to 7 by executing the executable instructions.

10. An electric vehicle, characterized by comprising: the electronic control unit according to any one of claims 8 to 9.

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