Control method for improving stability of electric vehicle, vehicle controller and electric vehicle

Abstract

The invention discloses a control method for improving the stability of an electric vehicle, a vehicle controller and the electric vehicle, relates to the field of new energy vehicles, and can be applied to pure electric vehicles and hybrid vehicles. The control method comprises the steps that in the running process of the electric vehicle, before the first moment when at least one wheel of the electric vehicle makes contact with a low-attachment road surface, the acting force output by an actuator of the active suspension is controlled to be first acting force. And after the first moment when the at least one wheel makes contact with the low-attachment road surface, the action force output by an actuator of the active suspension is controlled to be increased from the first action force to the second action force. Wherein the adhesion coefficient between at least one wheel and the low-adhesion road surface is smaller than the adhesion coefficient between at least one wheel and the road surface before the first moment. According to the scheme, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, so that the limit friction force of the wheel is increased, the road holding force of the wheel is effectively improved, slipping or locking on a low-attachment road surface is avoided, and the stability and safety of a vehicle on the low-attachment road surface are improved.

Description

Technical Field

[0001] The present application relates to the field of electric vehicles, and more particularly, to a control method for improving the stability of an electric vehicle, a vehicle controller, and an electric vehicle. Background Art

[0002] As driving environments become increasingly complex, such as wet, icy, or dusty road conditions, the adhesion coefficient between wheels and the road becomes low, and tires can easily lose grip, leading to wheel locking or slipping, compromising vehicle safety. Traditional solutions rely on hardware or accessories to achieve safe driving. For example, installing tires with a higher friction coefficient, switching to winter tires in rainy or snowy conditions, and using snow chains increase the friction coefficient between the tires and the road to help the car maintain stability on low-adhesion surfaces. However, these solutions are costly and inconvenient to use.

[0003] Therefore, how to improve the stability of electric vehicles when traveling on low-adhesion roads is a problem that needs to be solved. Summary of the Invention

[0004] The present application provides a control method for the active suspension of an electric vehicle, a vehicle controller, and an electric vehicle. When the electric vehicle enters a low-adhesion road surface, the active suspension is controlled to dynamically adjust the vertical load of the wheel, thereby increasing the ultimate friction of the wheel, effectively improving the wheel's grip, avoiding slipping or locking on the low-adhesion road surface, and improving the vehicle's stability and safety on the low-adhesion road surface.

[0005] In a first aspect, the present application provides a control method for improving the driving stability of an electric vehicle on a low-adhesion road surface. The control method is used to adjust the actuating force output by an actuator of an active suspension during driving of the electric vehicle to improve the driving stability of the electric vehicle. The control method includes, during driving of the electric vehicle on the road, before a first moment when at least one wheel of the electric vehicle contacts the low-adhesion road surface, controlling the actuating force output by the actuator of the active suspension to be a first actuating force. After the first moment when the at least one wheel contacts the low-adhesion road surface, controlling the actuating force output by the actuator of the active suspension to increase from the first actuating force to a second actuating force. The adhesion coefficient between the at least one wheel and the low-adhesion road surface is less than the adhesion coefficient between the at least one wheel and the road surface before the first moment.

[0006] The electric vehicle can be an electric vehicle or a hybrid vehicle. It can have a distributed drive motor or a centralized drive motor architecture, with multiple drive motors and multiple motor controllers. The drive motor can be a wheel-side motor or a hub motor, and can independently drive one wheel of the vehicle.

[0007] A low-adhesion road surface is one with a low coefficient of adhesion to the wheels. The coefficient of adhesion is the ratio of adhesion to the normal pressure on the wheel and is determined by the road surface and tire. The higher the coefficient, the greater the available adhesion. When an electric vehicle encounters a low-adhesion road surface, the coefficient of adhesion between the vehicle's wheels and the road surface decreases. When a vehicle travels on a low-adhesion road surface, the wheels have less grip, making it more likely to slip or lock, resulting in reduced stability.

[0008] The active suspension of an electric vehicle connects the vehicle's body and wheels, providing support, cushioning, and stability during driving. Each wheel is individually connected to the vehicle's body via an active suspension. The active suspension includes an actuator, the core executive component of the active suspension system. The actuator is responsible for adjusting the suspension's stiffness, damping, or actively applying force in real time based on control commands, achieving precise control of the vehicle's posture and vibration.

[0009] During the driving process of the electric vehicle, before the first moment, the electric vehicle has not entered a low-adhesion road surface, and the adhesion coefficient between the electric vehicle's wheels and the road surface is relatively large. At this time, the electric vehicle's wheels have a large grip, the wheel force is within the Kam's circle friction boundary, and the adhesion margin is large. The active suspension control does not need to consider wheel slip at this time, and the actuating force output by the actuator controlling the active suspension is the first actuating force. In one embodiment, the road surface is flat, the electric vehicle body is stable, and the active suspension does not need to deal with the vibration of the electric vehicle. At this time, the first actuating force is equal to zero. In another embodiment, the road surface is relatively bumpy, and the active suspension needs to isolate the vibration and bumps of the road surface by adjusting the actuating force output by the actuator. At this time, the first actuating force is not equal to zero and is changing.

[0010] At a first moment, at least one wheel of the electric vehicle contacts a low-adhesion road surface, and the adhesion coefficient between the at least one wheel and the road surface decreases. The adhesion coefficient between the at least one wheel and the road surface at and after the first moment is less than the adhesion coefficient between the at least one wheel and the road surface before the first moment. At this point, the wheels of the electric vehicle are at or outside the boundary of the Kamm's circle friction force, with a small adhesion margin. The wheels are prone to slippage or locking, resulting in poor stability.

[0011] After the first moment, the actuating force output by the actuator controlling the active suspension increases from the first actuating force to the second actuating force. By increasing the actuating force output by the actuator of the active suspension, the active suspension generates a greater vertical force on the wheel, thereby generating a greater vertical force on the ground by the wheel. The ultimate adhesion that the wheel can utilize increases, the wheel becomes less likely to slip or lock, and driving stability is enhanced.

[0012] In one implementation, the adhesion coefficient between the wheel and the low-adhesion road surface is less than or equal to an adhesion threshold. This adhesion threshold is pre-calibrated based on actual vehicle testing and / or model calculations, or is pre-set based on a comprehensive consideration of vehicle requirements and performance. When the adhesion coefficient between the wheel and the low-adhesion road surface is less than the adhesion threshold, the actuating force output by the actuator controlling the active suspension increases from a first actuating force to a second actuating force.

[0013] According to the solution of the present application, when an electric vehicle enters a low-adhesion road surface, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, thereby increasing the ultimate friction of the wheel, effectively improving the grip of the wheel, avoiding slipping on the low-adhesion road surface, and improving the stability and safety of the vehicle on the low-adhesion road surface.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the control method further includes, after the first moment, while the electric vehicle is traveling on a low-adhesion road surface, increasing the actuating force output by the actuator controlling the active suspension as the accelerator pedal opening of the electric vehicle increases.

[0015] The accelerator pedal in this application may also be referred to as the accelerator pedal or the accelerator pedal. The opening of the accelerator pedal can indicate the driving force required by the driver. The larger the opening of the accelerator pedal, the greater the driver's demand for driving, and the corresponding torque required to be output by the drive motor is also greater. The electric vehicle controls the drive motor to output the torque indicated by the accelerator pedal opening according to the opening of the accelerator pedal. The larger the opening of the accelerator pedal, the greater the torque output by the drive motor, and the smaller the opening of the accelerator pedal, the smaller the torque output by the drive motor. The torque output by the drive motor changes with the opening of the accelerator pedal.

[0016] After the first moment, while the electric vehicle is driving on a low-adhesion road, the driver depresses the accelerator pedal, increasing the opening of the accelerator pedal, thereby increasing the torque output by the electric vehicle's drive motor. At this point, the wheels are driven by the torque output by the drive motor, experiencing an increase in the longitudinal force, which is in the same direction as the wheel's travel. As the longitudinal force on the wheels increases, the net force acting on the wheels also increases. This net force may exceed the ground's limit friction, causing the wheels to slip and affecting the electric vehicle's driving stability. By increasing the force output by the active suspension's actuator, the active suspension generates a greater vertical force on the wheels, which in turn generates a greater vertical force on the ground. This increases the maximum adhesion available to the wheels, making them less likely to slip or lock, thereby enhancing driving stability.

[0017] According to the solution of the present application, when an electric vehicle accelerates or starts on a low-adhesion road surface, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, thereby increasing the ultimate friction force of the wheel, effectively improving the grip of the wheel, and avoiding the vehicle from slipping during acceleration or starting on a low-adhesion road surface, thereby improving the stability and safety of the electric vehicle.

[0018] In combination with the first aspect, in certain implementations of the first aspect, the control method also includes, after the first moment, while the electric vehicle is traveling on a low-adhesion road surface, increasing the actuating force output by the actuator controlling the active suspension as the brake pedal opening of the electric vehicle increases.

[0019] The brake pedal in this application may also be referred to as the deceleration pedal or brake pedal. The opening of the brake pedal can indicate the amount of braking force required by the driver. The larger the opening of the brake pedal, the greater the driver's demand for braking, and the greater the braking force required by the brake system. When the vehicle is in normal driving, the brake system can output the braking force indicated by the opening of the brake pedal based on the opening of the brake pedal. The larger the opening of the brake pedal, the greater the braking force output by the brake system, and the smaller the opening of the brake pedal, the smaller the braking force output by the brake system. The braking force output by the brake system changes with the opening of the brake pedal.

[0020] After the first moment, while the electric vehicle is traveling on a low-adhesion road, the driver depresses the brake pedal, increasing the degree of brake pedal opening. This increases the reverse torque output by the electric vehicle's powertrain or the braking force output by the braking system. This reverse torque is used to brake the electric vehicle's wheels. At this point, the longitudinal force acting on the wheels increases, and the direction of this longitudinal force is opposite to the direction of travel. As the longitudinal force acting on the wheels increases, the net force acting on the wheels also increases. This net force may exceed the maximum friction force of the ground, causing the wheels to lock and affecting the driving stability of the electric vehicle. By increasing the force output by the active suspension's actuator, the active suspension generates a greater vertical force on the wheels, which in turn generates a greater vertical force on the ground. This increases the maximum adhesion available to the wheels, making them less likely to slip or lock, thereby enhancing driving stability.

[0021] According to the solution of the present application, when an electric vehicle decelerates or brakes on a low-adhesion road surface, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, thereby increasing the ultimate friction force of the wheel, effectively improving the grip of the wheel, avoiding the vehicle from locking during deceleration or braking on a low-adhesion road surface, and improving the stability and safety of the electric vehicle's driving.

[0022] In combination with the first aspect, in certain implementations of the first aspect, the control method further includes, after the first moment, while the electric vehicle is traveling on a low-adhesion road surface, increasing the actuating force output by the actuator controlling the active suspension as the steering wheel of the electric vehicle is rotated to one side.

[0023] After the first moment, while the electric vehicle is driving on a low-adhesion road, the driver turns the steering wheel to one side, controlling the electric vehicle to steer to one side. At this point, the lateral force acting on the wheel increases to achieve the lateral steering, and the direction of the lateral force is perpendicular to the longitudinal force acting on the wheel. As the lateral force acting on the wheel increases, the net force acting on the wheel also increases. The net force acting on the wheel may exceed the maximum friction force of the ground, causing the wheel to slip, the electric vehicle to skid, understeer, or oversteer, affecting the driving stability of the electric vehicle. By increasing the actuating force output by the active suspension actuator, the active suspension generates a greater vertical force on the wheel, thereby generating a greater vertical force on the ground. The maximum adhesion force that the wheel can utilize increases, making the wheel less likely to slip, thereby enhancing driving stability.

[0024] According to the solution of the present application, when an electric vehicle turns on a low-adhesion road surface, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, thereby increasing the ultimate friction force of the wheel, effectively improving the grip of the wheel, avoiding the vehicle from slipping during the turning process on a low-adhesion road surface, and improving the stability and safety of the electric vehicle's driving.

[0025] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes: after a first moment, the two front wheels and the two rear wheels of the electric vehicle contact the low-adhesion road surface in turn, first controlling the actuating force output by the actuators of the active suspension corresponding to the two front wheels to increase, and then controlling the actuating force output by the actuators of the active suspension corresponding to the two rear wheels to increase.

[0026] It should be understood that each wheel of an electric vehicle is connected to the vehicle body via a separate active suspension, and each active suspension includes an actuator. In this application, the active suspension corresponding to the front wheels refers to the active suspension connecting the front wheels to the vehicle body, and the active suspension corresponding to the rear wheels refers to the active suspension connecting the rear wheels to the vehicle body. The actuators of the four active suspensions each output an actuating force, the magnitude of which is controlled based on the wheel to which the active suspension corresponds, and the timing at which the four active suspension actuators output the actuating force varies.

[0027] At the first moment, the electric vehicle begins to enter a low-adhesion road surface. The two front wheels of the electric vehicle enter the low-adhesion road surface first, and the extreme adhesion of the two front wheels becomes smaller. The active suspension corresponding to the front wheels first controls the actuator output to increase the actuating force. Then the two rear wheels of the electric vehicle enter the low-adhesion road surface, and the extreme adhesion of the two rear wheels also becomes smaller. The active suspension corresponding to the rear wheels then controls the actuator output to increase the actuating force.

[0028] According to the solution of the present application, when the wheels of the electric vehicle enter a low-adhesion road surface one after another, the active suspensions corresponding to the front and rear wheels are controlled to increase the actuating force output by the actuators in turn, thereby effectively improving the grip of the wheels and maintaining the balance of the actuating force output by the front and rear active suspension actuators of the vehicle, thereby avoiding slipping of the vehicle during steering on a low-adhesion road surface and improving the driving stability and safety of the electric vehicle.

[0029] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes that after the first moment, the smaller the adhesion coefficient between the wheel and the road surface, the greater the second actuating force output by the actuator controlling the active suspension.

[0030] After the first moment, the actuating force output by the actuator controlling the active suspension increases from the first actuating force to the second actuating force. The magnitude of this second actuating force affects wheel friction. When the wheel's adhesion coefficient is lower, the ultimate adhesion between the wheel and the ground is lower. A greater second actuating force increases the available adhesion of the wheel, making it more stable and less likely to slip or lock.

[0031] According to the solution of the present application, the smaller the adhesion coefficient between the wheel and the ground, the greater the vertical force generated by the active suspension on the wheel, thereby increasing the maximum adhesion that the wheel can utilize, making the wheel less likely to slip or lock, thereby enhancing driving stability.

[0032] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes, after a first moment, while the electric vehicle is traveling on a low-adhesion road surface, controlling the actuating force output by the actuator of the active suspension to increase as the torque output by the powertrain of the electric vehicle increases.

[0033] After the first moment, when the electric vehicle starts or accelerates on a low-adhesion road, the greater the torque output by the electric vehicle's power extension, the greater the longitudinal force on the wheel, and accordingly, the greater the net force on the wheel. At this point, the active suspension actuator needs to be controlled to output a greater actuating force, which generates a greater vertical force on the wheel and increases the wheel's maximum available adhesion.

[0034] According to the solution of the present application, when an electric vehicle accelerates or starts on a low-adhesion road surface, the greater the torque output by the powertrain, the greater the vertical force exerted on the wheels by controlling the active suspension, thereby increasing the maximum adhesion that the wheels can utilize, thereby avoiding the vehicle from slipping during acceleration or starting on a low-adhesion road surface and improving the stability and safety of the electric vehicle's driving.

[0035] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes, after the first moment, while the electric vehicle is traveling on a low-adhesion road surface, increasing the actuating force output by the actuator controlling the active suspension as the braking force output by the braking system of the electric vehicle increases.

[0036] After the first moment, the electric vehicle decelerates or brakes on a low-adhesion road surface. The greater the braking force output by the electric vehicle's braking system, the greater the longitudinal force on the wheel, and accordingly, the greater the net force on the wheel. At this point, the active suspension actuator needs to be controlled to output a greater actuating force, causing the active suspension to exert a greater vertical force on the wheel, thereby increasing the wheel's maximum available adhesion.

[0037] When an electric vehicle decelerates or brakes on a low-adhesion road surface, the greater the reverse torque output by the electric vehicle's powertrain, which is used to brake the wheels. The direction of the reverse torque is opposite to the direction of the torque output when the powertrain drives the wheels, and the greater the actuating force output by the actuator controlling the active suspension.

[0038] According to the solution of the present application, when an electric vehicle accelerates or starts on a low-adhesion road surface, the greater the torque output by the powertrain, the greater the vertical force exerted on the wheels by controlling the active suspension, thereby increasing the maximum adhesion that the wheels can utilize, thereby avoiding the vehicle from slipping during acceleration or starting on a low-adhesion road surface and improving the stability and safety of the electric vehicle's driving.

[0039] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes, after the first moment, while the electric vehicle is traveling on a low-adhesion road, increasing the actuating force output by the actuator controlling the active suspension as the steering angle of the electric vehicle increases.

[0040] After the first moment, the electric vehicle turns on a low-adhesion road. The greater the steering wheel angle, the greater the lateral force on the wheels, and correspondingly, the greater the net force on the wheels. At this point, the active suspension actuator needs to be controlled to output a greater actuating force, which generates a greater vertical force on the wheels and increases the maximum adhesion available to the wheels.

[0041] According to the solution of the present application, when an electric vehicle turns on a low-adhesion road surface, the greater the steering angle, the greater the vertical force exerted on the wheels by controlling the active suspension, thereby increasing the maximum adhesion that the wheels can utilize, avoiding the vehicle from slipping during acceleration or starting on a low-adhesion road surface, and improving the stability and safety of the electric vehicle's driving.

[0042] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes controlling the actuator of the active suspension to output a first actuating force when the adhesion parameter ρ of at least one wheel is less than a second threshold value, and the adhesion parameter ρ is used to indicate the ratio of the friction force exerted on the wheel to the limit friction force between the wheel and the road surface; when the adhesion parameter ρ of at least one wheel is greater than or equal to the second threshold value, controlling the actuator of the active suspension to output a first actuating force to increase from the first actuating force to the second actuating force.

[0043] The adhesion parameter indicates the ratio of the friction force applied to the wheel to the maximum friction force between the wheel and the road surface. As the vertical load on the wheel increases, the maximum friction force it can utilize increases, reflected in the wider boundary of the adhesion Kam's circle. When the friction force applied to the wheel is within the adhesion Kam's circle, the further away from the boundary, the greater the wheel's adhesion margin. The adhesion parameter characterizes how well the wheel adheres to the road surface. The smaller the adhesion parameter, the greater the adhesion margin and the better the adhesion stability. Therefore, the adhesion parameter can be used to judge wheel stability.

[0044] When the wheel adhesion parameter is less than the second threshold, it indicates that the wheel is within the friction boundary, the wheel adhesion margin is high, and the electric vehicle has good stability. In this case, the actuating force output by the actuator controlling the active suspension is the first actuating force. When the wheel adhesion parameter is greater than or equal to the second threshold, it indicates that the wheel is within or outside the friction boundary and is prone to slip or locking. In this case, the actuating force output by the actuator controlling the active suspension increases from the first actuating force to the second actuating force.

[0045] According to the solution of the present application, the wheel state is judged by the adhesion rate parameter, the response speed is fast, the accuracy of suspension control is improved, and miscontrol is avoided.

[0046] In conjunction with the first aspect, in certain implementations of the first aspect, the attachment rate parameter ρ satisfies:

[0047]

[0048] Among them, F x is the longitudinal force on at least one wheel, F y is the lateral force on at least one wheel, μ is the adhesion coefficient between at least one wheel and the road, F z is the vertical force acting on at least one wheel.

[0049] The sensors of electric vehicles monitor the stress state of the wheels in real time, detect the longitudinal force, lateral force and vertical force acting on the wheels, and detect the adhesion coefficient between the wheels and the road surface, thereby calculating the adhesion rate parameters according to the formula.

[0050] In combination with the first aspect, in certain implementations of the first aspect, the control method specifically includes controlling the actuating force output by the actuator of the active suspension to increase from a first actuating force to a second actuating force when the adhesion parameter ρ of at least one wheel is greater than or equal to a second threshold value so that the adhesion parameter ρ of the wheel is reduced to less than the second threshold value, and the second actuating force is inversely proportional to the adhesion coefficient of the road surface.

[0051] The wheel adhesion parameter reflects the utilization of the wheel's adhesion to the ground. The smaller the adhesion parameter, the greater the adhesion margin and the better the stability of the electric vehicle. Therefore, in order to increase the stability of the electric vehicle, the wheel adhesion parameter ρ needs to be controlled to be less than the second threshold. The greater the actuating force output by the active suspension actuator, the greater the vertical force on the wheel, and thus the smaller the adhesion parameter.

[0052] In a second aspect, the present application provides a vehicle controller for executing the control method as in the first aspect and its various implementations. The vehicle controller is used to connect to sensors of the electric vehicle, and the sensors are used to detect the adhesion coefficient between at least one wheel and the road surface and the force exerted on at least one wheel.

[0053] In a third aspect, the present application provides an electric vehicle, which includes a vehicle controller, an accelerator pedal, a brake pedal and a steering wheel as in the second aspect, the accelerator pedal is used to indicate the powertrain output torque of the electric vehicle, the brake pedal is used to indicate the powertrain or braking system output braking force of the electric vehicle, and the steering wheel angle is used to indicate the steering angle of the electric vehicle.

[0054] In combination with the third aspect, in certain implementations of the third aspect, the body of the electric vehicle is used to be connected to the four wheels through four active suspensions, and the vehicle controller is used to control the actuators of the four active suspensions to output unequal actuating forces.

[0055] The beneficial effects in other aspects can refer to the beneficial effects described in the first aspect and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0057] Figure 2 is a schematic diagram of the architecture of an electric vehicle provided in an embodiment of the present application;

[0058] Figure 3 Schematic diagram of an active suspension for an electric vehicle provided in an embodiment of the present application;

[0059] Figure 4 This is a schematic diagram of a wheel friction circle provided in an embodiment of the present application;

[0060] Figure 5 This is a schematic diagram of an active suspension control process for an electric vehicle provided in an embodiment of the present application;

[0061] Figure 6 This is a schematic diagram of active suspension control for an electric vehicle provided in an embodiment of the present application;

[0062] Figure 7 This is another schematic diagram of active suspension control for an electric vehicle provided in an embodiment of the present application;

[0063] Figure 8 This is another schematic diagram of active suspension control for an electric vehicle provided in an embodiment of the present application;

[0064] Figure 9 This is another schematic diagram of active suspension control for an electric vehicle provided in an embodiment of the present application;

[0065] Figure 10 This is a schematic diagram of an active suspension control process for an electric vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0066] The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0067] As the complexity of the vehicle driving environment increases, such as wet, icy or dusty road conditions, the adhesion coefficient between the wheels and the road is low, and the tires are prone to lose grip, causing the wheels to lock or slip, affecting vehicle safety.

[0068] In one possible implementation, an electric vehicle's electronic stability control system (ESC) monitors the vehicle's driving state through sensors. When it detects skidding or loss of control, it automatically adjusts power output and applies braking force to help restore vehicle stability. An electric vehicle's traction control system (TCS) prevents drive wheel slip by reducing engine torque or applying the brakes to ensure smooth starting and acceleration on low-adhesion roads. An electric vehicle's anti-lock braking system (ABS) prevents wheel lock during emergency braking, maintaining steering ability and effectively shortening braking distances and improving handling, especially on low-adhesion roads.

[0069] It should be understood that the above-mentioned electronic control system prevents the wheels from slipping or locking by controlling the longitudinal force or lateral force of the wheels, but cannot fundamentally increase the grip or friction of the wheels.

[0070] Based on the above problems, the present application provides a control method for the active suspension of an electric vehicle, a vehicle controller and an electric vehicle. When the electric vehicle enters a low-adhesion road surface, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, thereby increasing the ultimate friction force of the wheel, effectively improving the grip of the wheel, avoiding slipping or locking on the low-adhesion road surface, and improving the stability and safety of the vehicle on the low-adhesion road surface.

[0071] Figure 1 and Figure 2 Schematic diagram of the electric vehicle 10 architecture provided in an embodiment of the present application.

[0072] like Figure 1 As shown, the electric vehicle 10 includes a vehicle controller 20, a powertrain 50, a braking system 60, a suspension system 70, a power battery (not shown), and multiple wheels. The powertrain 50 includes a drive motor 30 and a motor controller 40. The motor controller 40 is used to output current to the drive motor 30 to control the drive motor 30 to output torque to drive the electric vehicle 10.

[0073] The vehicle controller provided in this application is the vehicle controller 20 or the motor controller 40 of the electric vehicle 10 or other separately set controller with control capabilities.

[0074] The electric vehicle 10 includes but is not limited to pure electric vehicle / battery electric vehicle (pure EV / battery EV), hybrid electric vehicle (HEV), range extended electric vehicle (REEV), plug-in hybrid electric vehicle (PHEV), new energy vehicle (NEV), etc.

[0075] The electric vehicle 10 has a drive architecture with a single drive motor, or a drive architecture with dual motors, or a drive architecture with three motors, or a drive architecture with four drive motors. The electric vehicle 10 can have a drive architecture with distributed four drive motors, where the drive motors are arranged on the sides of the driven wheels and are controlled by a separate motor controller 40. The electric vehicle 10 can also have a centralized drive motor drive architecture, where the drive motors for driving the two front wheels or the two rear wheels are arranged together. The motor controller 40 can be one or more. The motor controller 40 can correspond one-to-one to the drive motors, or one motor controller 40 can correspond to multiple drive motors. The motor controller 40 is used to control the output torque of one or more drive motors to drive the electric vehicle 10.

[0076] In one embodiment, if Figure 2 As shown in (a) of FIG, the electric vehicle 10 can be a distributed four-motor drive architecture, where the drive motors are arranged on the sides of the driven wheels and are controlled by separate motor controllers. The electric vehicle 10 can also be a Figure 2 In the centralized four-motor drive architecture shown in (b), two drive motors for driving two front wheels or two rear wheels are set together.

[0077] Exemplarily, the electric vehicle 10 includes four motor controllers, including motor controller 41, motor controller 42, motor controller 43, and motor controller 44. The four drive motors include drive motor 31, drive motor 31, drive motor 33, and drive motor 34. Motor controller 41 controls drive motor 31 to drive wheel 51, motor controller 42 controls drive motor 32 to drive wheel 52, motor controller 43 controls drive motor 33 to drive wheel 53, and motor controller 44 controls drive motor 34 to drive wheel 54.

[0078] In one embodiment, the electric vehicle 10 may also be Figure 2 The centralized drive motor architecture shown in (c) uses one drive motor to drive the two front wheels of the electric vehicle 10, and uses two drive motors to drive the two rear wheels of the electric vehicle 10 respectively.

[0079] In one embodiment, the aforementioned multiple architectures may be combined, for example, the front wheel drive adopts a distributed drive motor architecture and the rear wheel drive adopts a centralized drive motor architecture.

[0080] The electric vehicle 10 further includes an accelerator pedal and a brake pedal. The accelerator pedal is used to indicate the torque output to the wheels of the electric vehicle 10. The brake pedal is used to indicate the braking force output to the wheels of the electric vehicle 10.

[0081] In one embodiment, when the driver needs to drive the electric vehicle 10 during driving, the driver steps on the accelerator pedal, and the powertrain 50 outputs torque according to the opening of the accelerator pedal, thereby driving the wheels of the electric vehicle 10.

[0082] In one embodiment, the braking system 60 includes four wheel-end brake devices. When the driver needs to brake the electric vehicle 10 while driving, he or she presses the brake pedal. The braking system 60 outputs a clamping force to the brake disc based on the degree of brake pedal opening, thereby generating friction braking force, causing the electric vehicle 10 to brake.

[0083] In another embodiment, when the driver steps on the brake pedal, the powertrain 50 first outputs a reverse torque, which is used to brake the wheels. The direction of the reverse torque is opposite to the direction of the torque on the determined wheels.

[0084] The vehicle controller 20 is connected to the sensors and actuators of the electric vehicle 10 through a controller area network (CAN) bus, Ethernet, a local interconnect network (LIN) bus, a high-speed fault-tolerant network protocol (FlexRay) or other types of connection methods to interact with signals.

[0085] Figure 3 This is a schematic diagram of the active suspension provided in an embodiment of the present application.

[0086] In one embodiment, if Figure 3 As shown, the suspension system 70 of the electric vehicle 10 includes an active suspension. The active suspension is also called a fully active suspension. The active suspension includes an actuator 71, which is used to output an actuating force to adjust the state of the suspension. The active suspension is used to adjust the force output by the active suspension to the wheels by controlling the magnitude of the actuating force output by the actuator 71. The active suspension of the electric vehicle 10 is used to connect the body of the electric vehicle 10 and the wheels, and provide support, cushioning and stability during the driving of the electric vehicle 10. Each wheel is individually connected to the body of the electric vehicle 10 through an active suspension. The actuator 71 is the core executive component of the active suspension system. The actuator 71 is responsible for adjusting the stiffness, damping or active force of the suspension in real time according to the control instructions to achieve precise control of the body posture and vibration.

[0087] In one embodiment, the body of the electric vehicle 10 is used to be connected to the four wheels through four active suspensions, and the vehicle controller is used to control the actuators 71 of the four active suspensions to output unequal actuating forces.

[0088] Figure 4 A schematic diagram of the friction Kamm's circle provided in an embodiment of the present application is shown.

[0089] The limit friction force of the wheels in all directions is equal, and they are connected together to form a circle, which is called the Kamm circle or friction circle. Figure 4 As shown, the wheels of the electric vehicle 10 are subjected to a longitudinal force F x and lateral force F y The resultant force is F xy When the wheel is on the boundary of the friction circle, the limit friction force F of the wheel is xy =μF z , where μ is the road adhesion coefficient, F z is the vertical force on the tire. When the friction between the wheel and the road exceeds the Kamm's circle, the tire enters a sliding friction state. This manifests longitudinally as wheel slip, with acceleration slip manifesting as tire spin and deceleration slip manifesting as brake lock. Laterally, this manifests as vehicle sideslip, with front wheel slip causing understeer and rear wheel slip causing oversteer. Therefore, to ensure stable driving, the lateral and longitudinal forces on the wheels must be controlled within the Kamm's circle.

[0090] The vehicle controller is used to connect to sensors of the electric vehicle 10 , and the sensors are used to detect the adhesion coefficient between at least one wheel and the road surface and the force applied to at least one wheel.

[0091] The sensor of the electric vehicle 10 monitors the stress state of the wheel in real time and detects the longitudinal force F x , lateral force F y and vertical force F z , and detect the adhesion coefficient μ between the wheel and the road.

[0092] The friction force on the wheels and the maximum friction force that can be utilized affect the driving stability of electric vehicles. In the prior art, the modification of hardware such as tires is used to increase the adhesion coefficient μ between the wheels and the road surface. However, the electronic stability control system, traction control system and anti-lock braking system of electric vehicle 10 are achieved by optimizing the longitudinal force F x and lateral force F y To improve the driving stability of electric vehicles. None of the above methods change the vertical force F on the wheel. z .

[0093] In order to facilitate understanding of the embodiments of the present application, Figure 5-Figure 9 The control method, vehicle controller and electric vehicle 10 for improving the driving stability of the electric vehicle 10 on low-adhesion roads provided in the embodiment of the present application are described before the first moment t1, the first moment t1 and after the first moment t1 during the driving process of the electric vehicle 10.

[0094] It should be understood that the vehicle controller provided in this application may be a vehicle controller 20, a motor controller 40, or other separately provided controller with control capabilities.

[0095] The control method is used to adjust the actuating force output by the actuator 71 of the active suspension during the driving of the electric vehicle 10 to improve the driving stability of the electric vehicle 10 .

[0096] like Figure 5 and Figure 6 As shown, during the travel of the electric vehicle 10 , before the first moment t1 when at least one wheel of the electric vehicle 10 contacts the low-adhesion road surface, the actuating force output by the actuator 71 controlling the active suspension is the first actuating force.

[0097] During the driving process of electric vehicle 10, before first time t1, electric vehicle 10 has not entered a low-adhesion road surface, and the adhesion coefficient between the wheels of electric vehicle 10 and the road surface is relatively high. At this time, the wheels of electric vehicle 10 have strong grip, and the forces acting on the wheels are within the boundaries of the Kam's circle friction force, resulting in a large adhesion margin. Active suspension control does not need to consider wheel slip at this time, and the actuating force output by actuator 71 controlling the active suspension is the first actuating force.

[0098] In one embodiment, the road surface is flat, the body of the electric vehicle 10 is stable, and the active suspension does not need to handle the vibration of the electric vehicle 10 . In this case, the first actuating force is zero.

[0099] In another embodiment, the road surface is relatively bumpy, and the active suspension needs to isolate the vibration and bump of the road surface by adjusting the actuating force output by the actuator 71. At this time, the first actuating force is not equal to zero and changes in real time according to the vibration of the vehicle.

[0100] Continue to see Figure 5 and Figure 6 After a first moment t1 when at least one wheel contacts the low-adhesion road surface, the actuating force output by actuator 71 controlling the active suspension increases from a first actuating force to a second actuating force. The adhesion coefficient between the at least one wheel and the low-adhesion road surface is less than the adhesion coefficient between the at least one wheel and the road surface before the first moment.

[0101] At first moment t1, at least one wheel of electric vehicle 10 contacts a low-adhesion road surface. The adhesion coefficient between at least one wheel of electric vehicle 10 and the road surface decreases to less than or equal to the adhesion threshold, indicating that electric vehicle 10 enters a low-adhesion road surface. At this point, the wheels of electric vehicle 10 are at or outside the boundary of the Kam's circle friction force, with a small adhesion margin. The wheels are prone to slippage or locking, resulting in poor stability.

[0102] In one embodiment, after a first moment t1, the two front wheels and the two rear wheels of the electric vehicle sequentially contact a low-adhesion road surface, and the actuating forces output by the actuators of the active suspensions corresponding to the two front wheels are first controlled to increase, and then the actuating forces output by the actuators of the active suspensions corresponding to the two rear wheels are controlled to increase.

[0103] like Figure 5 As shown, at the first moment t1, the electric vehicle begins to enter a low-adhesion road surface. The two front wheels of the electric vehicle enter the low-adhesion road surface first, and the extreme adhesion of the two front wheels decreases. The active suspension corresponding to the front wheels first controls the actuator output to increase the actuating force. Then, the two rear wheels of the electric vehicle enter the low-adhesion road surface, and the extreme adhesion of the two rear wheels also decreases. The active suspension corresponding to the rear wheels then controls the actuator output to increase the actuating force.

[0104] After the first moment t1, the actuating force output by the actuator 71 of the active suspension is increased from the first actuating force to the second actuating force. By increasing the actuating force output by the actuator 71 of the active suspension, the active suspension generates a greater vertical force F on the wheel. z , so the vertical force F generated by the wheel on the ground z The larger the wheel is, the greater the maximum adhesion that the wheel can utilize, the less likely the wheel will slip or lock, and the driving stability will be enhanced.

[0105] It should be understood that the actuating forces output by the actuators 71 of the four active suspensions are determined based on the adhesion coefficient between each wheel and the road surface. The actuating forces output by the actuators 71 of the four active suspensions may be equal or unequal, and the actuating forces output by the actuators 71 of the active suspensions corresponding to the front and rear wheels may increase successively.

[0106] In one embodiment, after the first moment t1 when at least one wheel contacts the low-adhesion road surface, the smaller the adhesion coefficient between the wheel and the road surface, the greater the second actuating force output by the actuator 71 for controlling the active suspension.

[0107] The size of the second operating force affects the friction of the wheel. When the adhesion coefficient between the wheel and the ground is smaller, the limit adhesion between the wheel and the ground is smaller. At this time, the greater the second operating force, the greater the adhesion that the wheel can utilize, the more stable the wheel is, and it is less likely to slip or lock.

[0108] According to the solution of the present application, when the electric vehicle 10 enters a low-adhesion road surface, the vertical load of the wheel is dynamically adjusted by controlling the active suspension, thereby increasing the ultimate friction force of the wheel, effectively improving the grip of the wheel, avoiding slipping on the low-adhesion road surface, and improving the stability and safety of the vehicle on the low-adhesion road surface.

[0109] In one embodiment, if Figure 7As shown, after the first time t1 , when the electric vehicle is traveling on a low-adhesion road, the actuating force output by the actuator 71 for controlling the active suspension increases as the accelerator pedal opening of the electric vehicle 10 increases.

[0110] After the first moment t1, when the electric vehicle 10 is traveling on a low-adhesion road, the driver steps on the accelerator pedal to increase the opening of the accelerator pedal, thereby increasing the torque output by the drive motor of the electric vehicle 10. At this time, the wheels are driven by the torque output by the drive motor and are subjected to a longitudinal force F x Increase, longitudinal force F x The direction is the same as the direction of wheel travel. x As the force of the active suspension increases, the resultant force on the wheel increases accordingly, and the resultant force on the wheel may exceed the limit friction of the ground, causing the wheel to slip, affecting the driving stability of the electric vehicle 10. By increasing the actuating force output by the actuator 71 of the active suspension, the active suspension generates a greater vertical force F on the wheel. z , so the vertical force F generated by the wheel on the ground z The larger the wheel is, the greater the maximum adhesion that the wheel can utilize, the less likely the wheel will slip or lock, and the driving stability will be enhanced.

[0111] In one embodiment, after the first moment t1, when the electric vehicle is traveling on a low-adhesion road, the actuating force output by the actuator 71 controlling the active suspension increases as the torque output by the powertrain 50 of the electric vehicle increases.

[0112] At the first moment t1, the electric vehicle 10 starts or accelerates on a low-adhesion road. The greater the torque output by the powertrain 50 of the electric vehicle 10, the greater the longitudinal force F exerted on the wheel. x The larger the force, the greater the resultant force on the wheel. At this time, the greater the force output by the actuator 71 of the active suspension needs to be, so that the active suspension can generate a greater vertical force F on the wheel. z , improve the ultimate adhesion that the wheels can utilize.

[0113] When the electric vehicle 10 accelerates or starts, the loads on the front and rear axles of the electric vehicle 10 are transferred, increasing the vertical load on the wheels of the rear axle and decreasing the vertical load on the wheels of the front axle. When the electric vehicle 10 accelerates or starts on a low-adhesion road, the actuators of the active suspension are controlled to increase their output force to improve wheel adhesion. Because the vertical load on the wheels of the rear axle is greater than that on the wheels of the front axle, the output force of the active suspension actuators corresponding to the wheels of the rear axle is less than or equal to the output force of the active suspension actuators corresponding to the wheels of the front axle.

[0114] For example, when electric vehicle 10 accelerates or starts on a low-adhesion road, the accelerator pedal opening of electric vehicle 10 increases, partially shifting the vehicle's body load rearward. The vertical loads on the left and right front wheels decrease, while those on the left and right rear wheels increase. To improve wheel adhesion, the four active suspension actuators 71 corresponding to the four wheels are controlled to increase their output actuation force, with the actuation force output by the active suspension actuators 71 at the left and right rear wheels being less than or equal to the actuation force output by the active suspension actuators 71 at the left and right rear wheels.

[0115] In one embodiment, if Figure 8 As shown, after the first time t1 , when the electric vehicle 10 is traveling on a low-adhesion road surface, the actuating force output by the actuator 71 for controlling the active suspension increases as the brake pedal opening of the electric vehicle 10 increases.

[0116] After the first moment t1, when the electric vehicle 10 is traveling on a low-adhesion road, the driver steps on the brake pedal to increase the opening of the brake pedal, thereby increasing the reverse torque output by the powertrain 50 of the electric vehicle 10 or increasing the braking force output by the brake system 60. At this time, the longitudinal force F x Increase, longitudinal force F x The direction is opposite to the direction of wheel travel. x As the force F increases, the resultant force on the wheel increases accordingly, which may exceed the limit friction of the ground, causing the wheel to lock and affecting the driving stability of the electric vehicle 10. By increasing the actuating force output by the actuator 71 of the active suspension, the active suspension generates a greater vertical force F on the wheel. z , so the vertical force F generated by the wheel on the ground z The larger the wheel is, the greater the maximum adhesion that the wheel can utilize, the less likely the wheel will slip or lock, and the driving stability will be enhanced.

[0117] In one embodiment, after the first moment t1, when the electric vehicle 10 is traveling on a low-adhesion road, the actuating force output by the actuator 71 controlling the active suspension increases as the braking force output by the braking system 60 of the electric vehicle increases.

[0118] After the first moment t1, the electric vehicle 10 decelerates or brakes on a low-adhesion road surface. The greater the braking force output by the braking system 60 of the electric vehicle 10, the greater the longitudinal force F exerted on the wheel. x The larger the force, the greater the resultant force on the wheel. At this time, the greater the force output by the actuator 71 of the active suspension needs to be, so that the active suspension can generate a greater vertical force F on the wheel. z , improve the ultimate adhesion that the wheels can utilize.

[0119] When the electric vehicle 10 decelerates or brakes on a low-adhesion road surface, the greater the reverse torque output by the powertrain 50 of the electric vehicle 10, which is used to brake the wheels and has a direction opposite to the direction of the torque output when the powertrain 50 drives the wheels, the greater the actuating force output by the actuator 71 that controls the active suspension.

[0120] When the electric vehicle 10 decelerates or brakes, the loads on the front and rear axles of the electric vehicle 10 shift, increasing the vertical load on the front axle wheels and decreasing the vertical load on the rear axle wheels. When the electric vehicle 10 decelerates or brakes on a low-adhesion road surface, the active suspension actuators are controlled to increase their output force to improve wheel adhesion. Because the vertical load on the front axle wheels is greater than the vertical load on the rear axle wheels, the output force of the active suspension actuators corresponding to the front axle wheels is less than or equal to the output force of the active suspension actuators corresponding to the rear axle wheels.

[0121] For example, when electric vehicle 10 decelerates or brakes on a low-adhesion road surface, the brake pedal opening angle of electric vehicle 10 increases, partially shifting the vehicle's body load forward. The vertical loads on the left and right front wheels increase, while those on the left and right rear wheels decrease. To improve wheel adhesion, the four active suspension actuators 71 corresponding to the four wheels are controlled to increase their output actuation force, with the actuation force output by the active suspension actuators 71 at the left and right rear wheels being greater than or equal to the actuation force output by the active suspension actuators 71 at the left and right rear wheels.

[0122] In one embodiment, if Figure 9 As shown, after the first moment t1, when the electric vehicle is traveling on a low-adhesion road, the actuating force output by the actuator 71 controlling the active suspension increases as the steering wheel of the electric vehicle 10 is turned to one side.

[0123] After the first moment t1, the electric vehicle 10 is traveling on a low-adhesion road, and the driver turns the steering wheel to one side to control the electric vehicle 10 to turn to one side. At this time, the lateral force F y Increase to achieve steering to one side, the lateral force F y The direction of the longitudinal force F on the wheel x Vertical. Due to the lateral force F on the wheel y As the force F increases, the resultant force on the wheel increases accordingly, and the resultant force on the wheel may exceed the limit friction of the ground, causing the wheel to slip, the electric vehicle 10 to skid, understeer, or oversteer, affecting the driving stability of the electric vehicle 10. By increasing the actuating force output by the actuator 71 of the active suspension, the active suspension generates a greater vertical force F on the wheel. z , so the vertical force F generated by the wheel on the ground zThe larger the wheel is, the greater the maximum adhesion that the wheel can utilize, the less likely the wheel will slip, and the driving stability will be enhanced.

[0124] In one embodiment, after the first moment t1 , when the electric vehicle 10 is traveling on a low-adhesion road, the actuating force output by the actuator 71 controlling the active suspension increases as the steering angle of the electric vehicle 10 increases.

[0125] After the first moment t1, the electric vehicle 10 turns on a low-adhesion road. The greater the turning angle of the steering wheel of the electric vehicle 10, the greater the lateral force F exerted on the wheel. y The larger the force, the greater the resultant force on the wheel. At this time, the greater the force output by the actuator 71 of the active suspension needs to be, so that the active suspension can generate a greater vertical force F on the wheel. z , improve the ultimate adhesion that the wheels can utilize.

[0126] When the electric vehicle 10 is turning, the centrifugal force causes the load of the electric vehicle 10 to shift, increasing the vertical load on the wheel on the outside of the turn and decreasing the vertical load on the wheel on the inside of the turn. Therefore, when the electric vehicle 10 is turning on a low-adhesion road, the active suspension actuator is controlled to increase its output force to improve wheel adhesion. Because the vertical load on the wheel on the outside of the turn is greater than that on the wheel on the inside of the turn, the active suspension actuator output force corresponding to the outside wheel is smaller than the active suspension actuator output force corresponding to the inside wheel.

[0127] For example, when electric vehicle 10 turns left on a low-adhesion road, the steering wheel of electric vehicle 10 turns left, partially shifting the vehicle's body load to the right. The vertical loads on the left front and left rear wheels decrease, while those on the right front and right rear wheels increase. To improve wheel adhesion, the four active suspension actuators 71 corresponding to the four wheels are controlled to increase their output actuation force, with the actuation force output by the active suspension actuators 71 at the left front and left rear wheels being less than or equal to the actuation force output by the active suspension actuators 71 at the right front and right rear wheels.

[0128] It should be understood that Figure 6-Figure 9 The diagram is only an example and the actual values ​​may differ from those shown in the diagram.

[0129] In one embodiment, when the adhesion parameter ρ of at least one wheel is less than a second threshold value, the actuating force output by the actuator 71 that controls the active suspension is a first actuating force, and the adhesion parameter ρ is used to indicate the ratio of the friction force exerted on the wheel to the limit friction force between the wheel and the road surface; when the adhesion parameter ρ of at least one wheel is greater than or equal to the second threshold value, the actuating force output by the actuator 71 that controls the active suspension increases from the first actuating force to the second actuating force.

[0130] Exemplarily, the attachment rate parameter ρ satisfies:

[0131]

[0132] Among them, F x is the longitudinal force on at least one wheel, F y is the lateral force on at least one wheel, μ is the adhesion coefficient between at least one wheel and the road, F z is the vertical force F acting on at least one wheel z .

[0133] Based on the Kam's circle force diagram, the adhesion parameter ρ quantitatively describes the relationship between tire forces and tire friction margins. The adhesion parameter indicates the ratio of the friction force acting on the wheel to the ultimate friction between the wheel and the road surface. As the vertical load on the wheel increases, the ultimate friction force it can utilize increases, reflected in the wider range of the adhesion Kam's circle boundary. When the friction force acting on the wheel is within the adhesion Kam's circle, the farther from the boundary, the greater the wheel's adhesion margin. The adhesion parameter characterizes the wheel's utilization of the road surface. The smaller the adhesion parameter, the greater the adhesion margin and the better the adhesion stability. Therefore, the adhesion parameter can be used to judge wheel stability.

[0134] When the wheel adhesion parameter is less than the second threshold, it indicates that the wheel is within the friction boundary, the wheel adhesion margin is high, and the electric vehicle 10 has good stability. In this case, the actuating force output by the actuator 71 controlling the active suspension is the first actuating force. When the wheel adhesion parameter is greater than or equal to the second threshold, it indicates that the wheel is within or outside the friction boundary and is prone to slip or locking. In this case, the actuating force output by the actuator 71 controlling the active suspension increases from the first actuating force to the second actuating force.

[0135] In one embodiment, when the adhesion parameter ρ of at least one wheel is greater than or equal to a second threshold value, the actuating force output by the actuator 71 controlling the active suspension is increased from a first actuating force to a second actuating force so that the adhesion parameter ρ of the wheel is reduced to less than the second threshold value, and the second actuating force is inversely proportional to the adhesion coefficient of the road surface.

[0136] The wheel adhesion parameter reflects the adhesion utilization of the wheel to the ground. The smaller the adhesion parameter, the greater the adhesion margin and the better the stability of the electric vehicle 10. Therefore, in order to increase the stability of the electric vehicle 10, the wheel adhesion parameter ρ needs to be controlled to be less than the second threshold. The greater the actuating force output by the actuator 71 of the active suspension, the greater the vertical force F exerted on the wheel. z The larger it is, the smaller the adhesion rate parameter is.

[0137] The second threshold is pre-calibrated based on actual vehicle experiments and / or model calculations, or is pre-set based on comprehensive consideration of vehicle requirements and vehicle performance. The second threshold is a value between 0 and 1.

[0138] When 0 < ρ < 1, the wheel force is within the friction boundary, and the tire has a high stability margin. When ρ = 1, the wheel is at the boundary. When ρ > 1, the wheel is outside the friction boundary and is prone to slip or lock. The wheel adhesion parameter ρ should be controlled within 0 to 1 to ensure that the tire force is always within the Kamm circle, effectively reducing the tire adhesion and improving the vehicle's stability and safety on low-adhesion roads.

[0139] The vehicle controller detects the longitudinal forces F of the four wheels through the state observer x , lateral force F y and the road adhesion coefficient μ, and calculate the tire adhesion rate ρ. When ρ is greater than the second threshold, it is determined that the tire adhesion margin is small. The actuating force output by the fully active suspension actuator 71 is obtained by calculation, and then by increasing F z Making ρ smaller than the second threshold increases vehicle stability.

[0140] It should be understood that there is a limit to increasing the vertical load of the wheel through the actuating force output by the actuator 71 of the active suspension, so the adhesion that can be increased is limited. When the actuating force output by the actuator 71 of the active suspension reaches the maximum, the electric vehicle 10 may still slip. At this time, it is necessary to cooperate with the electronic stability control system, traction control system and anti-lock braking system to maintain control on low-adhesion roads.

[0141] Figure 10 A flow chart of an active suspension control method provided in an embodiment of the present application is shown.

[0142] First, the vehicle controller monitors the longitudinal force F of the four wheels in real time through the state observer. x , lateral force F y The sensor monitors the tire stress status in real time and transmits the data to the vehicle controller.

[0143] Next, the vehicle controller calculates the current wheel adhesion parameter ρ and compares it with a preset second threshold. If the adhesion is greater than the second threshold, the vehicle controller calculates the required actuating force output by the active suspension actuator 71 and applies the corresponding actuating force through the actuator to increase the vertical force F on the wheel. z , increase the vertical force F z After that, the wheel adhesion parameter is calculated again until the adhesion parameter is less than the second threshold.

[0144] The solution proposed in this application incorporates a fully active suspension system to dynamically adjust the vertical load on the tires. This system monitors and dynamically adjusts vertical loads in real time, more precisely controlling tire adhesion and ensuring tire forces remain within the Kamm circle. This prevents tire slip, improves vehicle stability and safety, and addresses the issue of vehicle instability on low-adhesion roads. Furthermore, by optimizing the control algorithm, precise control of the suspension system is achieved, enhancing overall performance.

[0145] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A control method for improving the driving stability of an electric vehicle on a low-adhesion road, characterized in that: The control method is used to adjust the actuating force output by the actuator of the active suspension during the driving of the electric vehicle to improve the driving stability of the electric vehicle, and the control method includes: During the driving of the electric vehicle on the road, before a first moment when at least one wheel of the electric vehicle contacts a low-adhesion road surface, controlling the actuator of the active suspension to output a first actuating force; After the first moment when the at least one wheel contacts the low-adhesion road surface, controlling the actuator of the active suspension to increase the actuating force output from the first actuating force to a second actuating force; The adhesion coefficient between the at least one wheel and the low-adhesion road surface is smaller than the adhesion coefficient between the at least one wheel and the road surface before the first moment.

2. The control method according to claim 1, characterized in that: The control method further includes: After the first moment, while the electric vehicle is traveling on the low-adhesion road surface, the actuating force output by the actuator controlling the active suspension increases as the accelerator pedal opening of the electric vehicle increases.

3. The control method according to claim 1, wherein: The control method further includes: After the first moment, while the electric vehicle is traveling on the low-adhesion road surface, the actuating force output by the actuator controlling the active suspension increases as the brake pedal opening of the electric vehicle increases.

4. The control method according to claim 1, wherein: The control method further includes: After the first moment, while the electric vehicle is traveling on the low-adhesion road surface, the actuating force output by the actuator controlling the active suspension increases as the steering wheel of the electric vehicle is turned to one side.

5. The control method according to claim 1, characterized in that: The control method specifically includes: After the first moment, the two front wheels and the two rear wheels of the electric vehicle contact the low-adhesion road surface in sequence, and the actuating force output by the actuators of the active suspension corresponding to the two front wheels is first controlled to increase, and then the actuating force output by the actuators of the active suspension corresponding to the two rear wheels is controlled to increase.

6. The control method according to any one of claims 1 to 5, characterized in that: The control method specifically includes: After the first moment, the smaller the adhesion coefficient between the wheel and the road surface, the greater the second actuating force output by the actuator controlling the active suspension.

7. The control method according to any one of claims 2 to 6, characterized in that: The control method specifically includes: After the first moment, while the electric vehicle is traveling on the low-adhesion road surface, the actuating force output by the actuator controlling the active suspension increases as the torque output by the powertrain of the electric vehicle increases.

8. The control method according to any one of claims 3 to 7, characterized in that: The control method specifically includes: After the first moment, while the electric vehicle is traveling on the low-adhesion road surface, the actuating force output by the actuator controlling the active suspension increases as the braking force output by the braking system of the electric vehicle increases.

9. The control method according to any one of claims 4 to 8, characterized in that: The control method specifically includes: After the first moment, while the electric vehicle is traveling on the low-adhesion road surface, the actuating force output by the actuator controlling the active suspension increases as the steering angle of the electric vehicle increases.

10. The control method according to any one of claims 1 to 9, characterized in that: The control method specifically includes: When the adhesion parameter ρ of the at least one wheel is less than a second threshold, the actuating force output by the actuator controlling the active suspension is the first actuating force, wherein the adhesion parameter ρ is used to represent the relationship between the friction force exerted on the at least one wheel and the limit friction force between the at least one wheel and the road surface; When the adhesion parameter ρ of the at least one wheel is greater than or equal to the second threshold, the actuating force output by the actuator of the active suspension is controlled to increase from the first actuating force to a second actuating force.

11. The control method according to claim 10, characterized in that: The attachment rate parameter ρ satisfies: Among them, F x is the longitudinal force on at least one wheel, F y is the lateral force on the at least one wheel, μ is the adhesion coefficient between the at least one wheel and the road surface, F z is the vertical force applied to the at least one wheel.

12. The control method according to claim 10, characterized in that: The control method specifically includes: When the adhesion parameter ρ of at least one wheel is greater than or equal to the second threshold, the actuating force output by the actuator of the active suspension is controlled to increase from the first actuating force to the second actuating force so that the adhesion parameter ρ of the wheel is reduced to less than the second threshold, and the second actuating force is inversely proportional to the adhesion coefficient of the road surface.

13. A vehicle controller, characterized in that: The vehicle controller is used to execute the control method as described in any one of claims 1 to 12, and the vehicle controller is used to connect to the sensor of the electric vehicle, and the sensor is used to detect the adhesion coefficient between the at least one wheel and the road surface and the force exerted on the at least one wheel.

14. An electric vehicle, characterized in that: The electric vehicle includes a vehicle controller as described in claim 13, an accelerator pedal, a brake pedal and a steering wheel, the accelerator pedal is used to indicate the powertrain output torque of the electric vehicle, the brake pedal is used to indicate the powertrain or braking system output braking force of the electric vehicle, and the steering wheel angle is used to indicate the steering angle of the electric vehicle.

15. The electric vehicle according to claim 14, characterized in that The body of the electric vehicle is used to be connected to four wheels respectively through four active suspensions, and the vehicle controller is used to: The actuators controlling the four active suspensions respectively output unequal actuating forces.

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