Vehicle braking forward inclination relieving method, controller and vehicle

Abstract

The invention provides a braking forward inclination relieving method of a vehicle, a controller and the vehicle, and is applied to the technical field of electric vehicles so as to improve the comfort of the vehicle in the braking process. According to the braking forward inclination relieving method, when the deceleration of the vehicle is smaller than the preset deceleration at the first moment of the braking last stage when the vehicle travels forwards, the braking torque output by an electronic mechanical braking device is controlled to be smaller than the braking torque indicated by the braking pedal stroke of the vehicle. On the basis, the deceleration of the vehicle can be further properly reduced in a mode of actively reducing the braking torque output by the electronic mechanical braking device when the deceleration of the vehicle at the end of braking is small, so that forward inclination of a driver and passengers caused by sudden deceleration change when the deceleration of the vehicle at the end of braking is too large is relieved, and the driving and riding comfort is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicles, and particularly to a method for alleviating forward pitching during braking of a vehicle, a controller, and a vehicle. Background Art

[0002] In recent years, with the popularization of electric vehicles, in order to improve the user experience, the functions of electric vehicles have become more and more perfect. Among them, at the end of the braking of an electric vehicle, when the electric vehicle stops, it will rebound under the action of the vehicle body and the chassis suspension, causing the passenger's body to pitch forward due to deceleration, resulting in discomfort. In order to alleviate the forward pitching during braking and achieve the effect of comfortable braking, during the braking process of an electric vehicle, a relatively common method is to control the speed of the electric vehicle for braking according to the vehicle speed of the electric vehicle. However, controlling the electric vehicle to brake according to the vehicle speed will have a large error and low operability, and still affect the comfort of braking. Therefore, there is an urgent need to provide a solution to solve the above problems. Summary of the Invention

[0003] The present application provides a method for alleviating forward pitching during braking of a vehicle, a controller, and a vehicle, so as to improve the amplitude of forward pitching of the driver and passengers when the vehicle stops at the end of non-emergency braking and improve the comfort of braking.

[0004] To achieve the above object, the present application provides the following technical solutions.

[0005] In a first aspect, the present application provides a method for alleviating forward pitching during braking of a vehicle. The method for alleviating forward pitching during braking is used to control the output of the electro-mechanical braking device of the vehicle to output a braking torque at the end of braking when the vehicle is traveling. The method for alleviating forward pitching during braking includes: when the deceleration of the vehicle is less than or equal to a first preset deceleration and the vehicle speed is less than or equal to a first preset vehicle speed at a first moment, controlling the electro-mechanical braking device to output a first braking torque, and the first braking torque is less than the braking torque indicated by the braking pedal stroke of the vehicle at the first moment.

[0006] The greater the deceleration of the vehicle at the end of non-emergency braking, the easier it is to cause the driver and passengers to pitch forward. When the deceleration of the vehicle is less than or equal to the first preset deceleration and the vehicle speed is less than or equal to the first preset vehicle speed at the first moment, the method for alleviating forward pitching during braking provided by the present application controls the first braking torque output by the electro-mechanical braking device to be less than the braking torque indicated by the braking pedal stroke of the vehicle at the first moment, which can appropriately reduce the deceleration of the vehicle at the end of braking, so that the speeds of the vehicle body and the chassis can be synchronized, thereby improving the forward pitching of the driver and passengers caused by the sudden change of deceleration when the vehicle stops and improving the comfort of braking.

[0007] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: after the first moment, the braking pedal travel of the vehicle increases; at a second moment after the first moment, the vehicle speed is less than or equal to a second preset vehicle speed; controlling the electromechanical braking device to output a second braking torque, where the second braking torque is equal to the braking torque indicated by the braking pedal travel at the second moment, and the second preset vehicle speed is less than the first preset vehicle speed.

[0008] The increase in the braking pedal travel indicates that it is necessary to increase the braking torque output by the braking motor in the electromechanical braking device. However, increasing the braking torque output by the braking motor is likely to cause the vehicle occupants to pitch forward when the vehicle stops. After actively reducing the braking torque output by the electromechanical braking device of the vehicle, the vehicle speed being less than the second preset vehicle speed indicates that the vehicle is approaching a stop. At this time, restoring the braking torque output by the electromechanical braking device to the braking torque indicated by the braking pedal travel can stop the vehicle in time and is not likely to cause the vehicle occupants to pitch forward, while ensuring the normal output of the braking force when the vehicle stops.

[0009] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: at any moment between the first moment and the second moment, controlling the braking torque output by the electromechanical braking device to be equal to the first braking torque, or at any moment between the first moment and the second moment, controlling the braking torque output by the electromechanical braking device to be greater than the first braking torque and less than the braking torque indicated by the braking pedal travel at the corresponding same moment.

[0010] After the braking pedal travel increases during the process of the vehicle approaching a stop until it finally stops, the braking torque output by the electromechanical braking device can be constant at the first braking torque, or greater than the first braking torque but less than the braking torque indicated by the travel of the braking pedal. Based on this, while improving braking comfort, the braking torque output by the electromechanical braking device can be controlled according to actual needs, simplifying the control of the braking torque.

[0011] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: at a third moment after the first moment and before the second moment, when the driving distance of the vehicle from the first moment to the third moment is greater than a first preset distance, controlling the electromechanical braking device to increase the output braking torque.

[0012] The driving distance from the first moment to the third moment being greater than the first preset distance indicates that the braking distance of the vehicle is too long. At this time, by increasing the braking torque output by the electromechanical braking device, the deceleration of the vehicle can be increased, thereby reducing the braking distance of the vehicle and enhancing braking safety.

[0013] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: when the deceleration of the vehicle at a fourth moment after the first moment and before the second moment is less than or equal to a second preset deceleration, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the fourth moment, where the second preset deceleration is less than or equal to the first preset deceleration.

[0014] When the deceleration of the vehicle is very small, braking will not cause the occupants to pitch forward. At this time, restoring the braking torque output by the electromechanical braking device can stop the vehicle in time.

[0015] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: when the vehicle speed at the first moment is greater than a first preset vehicle speed, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke of the vehicle at the first moment.

[0016] When the vehicle speed is greater than the first preset vehicle speed, it indicates that the vehicle speed is relatively high. At this time, the braking torque output by the electromechanical braking device is equal to the braking torque indicated by the brake pedal stroke of the vehicle at the first moment to improve driving safety.

[0017] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: when the change rate of the brake pedal stroke at any moment between the first moment and the second moment is greater than a first preset change rate, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the first moment.

[0018] When the change rate of the brake pedal stroke at any moment between the first moment and the second moment is greater than the first preset change rate, it indicates that the vehicle needs to perform emergency braking. At this time, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the first moment can quickly increase the braking force of the vehicle, thereby quickly stopping the vehicle and avoiding safety accidents.

[0019] In one embodiment, the above-mentioned method for alleviating forward pitching during braking further includes: when the change rate of the brake pedal stroke at the first moment is greater than a first preset change rate, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the first moment.

[0020] When the change rate of the brake pedal stroke at the first moment is greater than the first preset change rate, it indicates that the vehicle needs to perform emergency braking. At this time, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the first moment can quickly increase the braking force of the vehicle, thereby quickly stopping the vehicle and avoiding safety accidents.

[0021] In one embodiment, the forward tilt mitigation method for braking further includes: when the vehicle is in an uphill driving condition and the road surface gradient on which the vehicle travels is greater than a first preset gradient, controlling the first braking torque to be inversely proportional to the road surface gradient at a first moment. When the vehicle is in a downhill driving condition and the road surface gradient on which the vehicle travels is greater than a second preset gradient, controlling the first braking torque to be proportional to the road surface gradient at the first moment.

[0022] When the vehicle is driving uphill, the weight of the vehicle itself will provide a gravity component opposite to the driving direction. Among them, when the road surface gradient is too large, the gravity component provided by the weight of the vehicle itself will cause the deceleration of the vehicle to be too large, resulting in the vehicle decelerating too quickly and causing the driver and passengers to lean forward. Reducing the braking torque output by the electromechanical braking device when the vehicle is in an uphill driving condition can avoid an increase in the deceleration of the vehicle, thereby preventing the driver and passengers from leaning forward at the end of braking.

[0023] When the vehicle is driving downhill, the weight of the vehicle itself will provide a gravity component in the same direction as the driving direction. Among them, when the road surface gradient is too large, the gravity component provided by the weight of the vehicle itself will cause the deceleration of the vehicle to decrease too quickly, resulting in an increase in the braking distance of the vehicle. Increasing the braking torque output by the electromechanical braking device when the vehicle is in a downhill driving condition can avoid the deceleration of the vehicle decreasing too quickly, thereby controlling the braking distance of the vehicle.

[0024] In one embodiment, the above-mentioned forward tilt mitigation method for braking further includes: when the wheel slip ratio of the vehicle is less than a first preset slip ratio, controlling the first braking torque to be proportional to the wheel slip ratio at a first moment. When the wheel slip ratio of the vehicle is greater than or equal to the first preset slip ratio, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the first moment.

[0025] The wheel slip ratio being less than the first preset slip ratio indicates that the vehicle is driving on a high-adhesion road surface. At this time, the braking torque output by the electromechanical braking device being proportional to the wheel slip ratio can timely adjust the braking torque output by the electromechanical braking device and can limit wheel slippage. The wheel slip ratio of the vehicle being greater than or equal to the first preset slip ratio indicates that the vehicle is driving on a low-adhesion road surface. At this time, the braking torque output by the electromechanical braking device is equal to the braking torque indicated by the brake pedal stroke at the first moment, which can avoid excessive wheel slippage.

[0026] In one embodiment, the above-mentioned forward tilt mitigation method for braking further includes: after a second moment, when the vehicle is in a driving condition, and at a fifth moment after the second moment, when the steering angle of the vehicle's steering wheel turns left by more than a first preset angle, controlling the braking torque output by the electromechanical braking device on the left side of the vehicle to be greater than the braking torque output by the electromechanical braking device on the right side of the vehicle.

[0027] When the steering angle of the vehicle's steering wheel to the left is greater than the first preset steering angle, it indicates that the vehicle needs to turn left. At this time, the braking torque output by the electromechanical braking device on the left side of the vehicle is greater than that output by the electromechanical braking device on the right side, which can ensure that the rotational speed of the right wheel is greater than that of the left wheel, thereby providing a turning moment to the left for the vehicle and helping the vehicle turn faster.

[0028] In one embodiment, the above-mentioned braking forward tilt mitigation method further includes: when the vehicle is in a reverse braking condition after the fifth moment, at the sixth moment after the fifth moment, the deceleration of the vehicle is less than or equal to the third preset deceleration and the vehicle speed is less than the third preset vehicle speed, controlling the third braking torque output by the electromechanical braking device, where the third braking torque is less than the braking torque indicated by the brake pedal stroke at the sixth moment and greater than the first braking torque.

[0029] When the deceleration of the vehicle during reverse driving is less than or equal to the third preset deceleration and the vehicle speed is less than the third preset vehicle speed, it indicates that the vehicle is in the end stage of reverse braking. At this time, the third braking torque output by the electromechanical braking device being less than the braking torque indicated by the brake pedal stroke can reduce the deceleration of the vehicle, thereby performing a comfortable braking on the vehicle. Among them, the third braking torque being greater than the above-mentioned first braking torque can ensure that the deceleration during comfortable braking at the end stage of reverse driving is greater than that during comfortable braking at the end stage of forward driving, thereby reducing the braking distance during reverse comfortable braking and improving the safety of reverse comfortable braking.

[0030] In one embodiment, when the vehicle is in a reverse condition, the above-mentioned braking forward tilt mitigation method further includes: at the seventh moment after the sixth moment, when the deceleration of the vehicle is less than the fourth preset deceleration, controlling the braking torque output by the electromechanical braking device to be equal to the braking torque indicated by the brake pedal stroke at the seventh moment.

[0031] During the non-emergency braking process when reversing, the deceleration of the vehicle being less than the fourth preset deceleration indicates that the vehicle is approaching a stop at the end stage of braking. At this time, the braking torque output by the electromechanical braking device being equal to the braking torque indicated by the brake pedal stroke can increase the deceleration of the vehicle, thereby stopping the vehicle faster and preventing the braking distance from being too long. In addition, the fourth preset deceleration, which is the judgment threshold during reverse braking, being greater than the above-mentioned second preset deceleration can increase the braking torque output by the electromechanical braking device earlier, thereby further reducing the braking distance at the end stage of reverse driving and improving the safety of comfortable braking when the vehicle is reversing.

[0032] Second aspect, the present application provides a controller, which is used to implement the braking forward tilt mitigation method in any one of the above first aspects. The controller is used to communicate with the electromechanical braking device of the vehicle and control the braking motor of the electromechanical braking device to output braking torque.

[0033] Third aspect, the present application provides a vehicle, which uses the braking forward tilt mitigation method in any one of the above first aspects for braking control.

[0034] Regarding the technical principles and technical effects of the above second and third aspects, reference can be made to the description of the above first aspect, and the present application will not elaborate herein. Description of the Drawings

[0035] Figure 1 A schematic diagram of an electric vehicle provided by an embodiment of the present application;

[0036] Figure 2 Another schematic diagram of an electric vehicle provided by an embodiment of the present application;

[0037] Figure 3 A schematic diagram of a braking system provided by an embodiment of the present application;

[0038] Figure 4 A schematic diagram of an electromechanical braking device provided by an embodiment of the present application;

[0039] Figure 5 A schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0040] Figure 6 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0041] Figure 7 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0042] Figure 8 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application. Detailed Embodiments

[0043] In the present application, "in one embodiment" is used to give examples, illustrations or explanations. The solutions described as "in one embodiment" in the present application should not be construed as being more preferred or having more advantages than the solutions of other embodiments. Rather, using "in one embodiment" is intended to present the inventive concept of the present application in a specific manner.

[0044] With the development of electric vehicles, the driving experience of electric vehicles has received increasing attention. Among them, the braking performance of electric vehicles is a key factor affecting the driving experience of electric vehicles. During the braking process of an electric vehicle, the end stage of braking refers to the process in which the vehicle speed of the electric vehicle decreases from a very small value to zero, that is, the process in which the electric vehicle changes from approaching a stop to a complete stop and has no relative movement with the ground. During the braking process of an electric vehicle, under the action of deceleration, the vehicle's suspension is compressed. After the braking of the electric vehicle ends, although the electric vehicle has actually stopped, the body of the electric vehicle will rebound under the action of the suspension, resulting in the electric vehicle shaking, which affects the driving experience.

[0045] When braking an electric vehicle, the braking of the electric vehicle includes emergency braking and non-emergency braking. Emergency braking is a process of decelerating the electric vehicle to a stop within the shortest distance in a very short time. During emergency braking, the deceleration of the electric vehicle is relatively large so that the electric vehicle can quickly stop within the shortest distance. The non-emergency braking process is a process of controlling the electric vehicle to slowly decelerate to a stop over a longer period of time. During the non-emergency braking process, the deceleration of the electric vehicle is relatively small so that the electric vehicle can slowly stop through a longer braking distance.

[0046] During the end stage of non-emergency braking of an electric vehicle, in order to reduce the shaking of the electric vehicle and make the braking process more comfortable, some related technologies reduce the deceleration of the electric vehicle by reducing the hydraulic pressure of the hydraulic braking system at the end stage of braking. However, the above solutions usually control the hydraulic braking force of the hydraulic braking system according to the wheel speed detected by the wheel speed sensor, resulting in inaccurate judgment of the control timing and still affecting the driving experience.

[0047] To solve the above problems, the embodiments of the present application provide a method for alleviating forward tilt during braking of a vehicle, a controller and a vehicle. Among them, the method for alleviating forward tilt during braking of a vehicle provided by the embodiments of the present application actively controls the braking torque output by the electromechanical braking device to be less than the braking torque indicated by the braking pedal stroke when the deceleration of the vehicle is less than or equal to a first preset deceleration and the vehicle speed of the vehicle is less than a first preset vehicle speed during the non-emergency braking process when the vehicle is driving, so as to further reduce the deceleration of the vehicle, thereby reducing the forward tilt feeling generated when the vehicle stops and improving the driving experience.

[0048] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings, taking the vehicle as the electric vehicle 10 as an example.

[0049] Figure 1 A schematic diagram of an electric vehicle provided by an embodiment of the present application. As Figure 1As shown, the electric vehicle 10 generally includes a drive system 100, a braking system 200, a power battery 300, and a controller 400. The drive system 100, the braking system 200, and the controller 400 are generally communicatively connected through a communication bus and interact with signals. Among them, the communication bus includes a controller area network (CAN) bus, a local interconnect network (LIN) bus, a flexray, or other types of buses, which are not limited herein. In addition, the drive system 100 is used to drive the wheels of the electric vehicle 10 to rotate so as to drive the electric vehicle 10 to travel. The braking system 200 is used to brake the wheels of the electric vehicle 10 to decelerate the electric vehicle 10. The power battery 300 is used to supply power to the drive system 100, the braking system 200, the controller 400, etc.

[0050] The power battery 300 in the embodiments of the present application may be a lithium-ion battery, a lithium-metal battery, a lead-acid battery, a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-sulfur battery, a lithium-air battery, or a sodium-ion battery, etc., which are not limited herein. In terms of scale, the power battery 300 in the embodiments of the present application may be a single battery cell, or a battery module or a battery pack, which are not limited herein. The power battery 300 can also supply power to other electrical devices in the electric vehicle 10, such as supplying power to the in-vehicle air conditioner, the in-vehicle player, etc.

[0051] Figure 2 Another schematic diagram of the electric vehicle provided by the embodiments of the present application. As Figure 2 shown, in one embodiment, the drive system 100 includes a motor controller 110, a drive motor 120, and a speed reducer 130. The motor controller 110 is used to receive the direct current output by the power battery 300 and output alternating current to control the drive motor 120 to output a driving torque. The drive motor 120 drives the wheels of the electric vehicle 10 through the speed reducer 130.

[0052] In one embodiment, the electric vehicle 10 further includes a rotational speed measurement unit 140. As Figure 2 shown, the rotational speed measurement unit 140 is used to detect the rotational speed of the drive motor 120 of the electric vehicle 10. The controller 400 can calculate the vehicle speed of the electric vehicle 10 according to the rotational speed of the drive motor 120 detected by the rotational speed measurement unit 140, and actively adjust the braking torque output by the braking motor in the electromechanical braking device 210 according to the vehicle speed of the electric vehicle 10 during the braking process. Among them, the rotational speed measurement unit 140 can select a resolver. Through the resolver, the rotational speed of the drive motor can be detected more quickly and accurately, so as to calculate the vehicle speed of the electric vehicle.

[0053] In one embodiment, still as Figure 2As shown, the electric vehicle 10 further includes an inertial measurement unit 150 (IMU). Among them, the inertial measurement unit 150 can detect the deceleration of the electric vehicle 10. The controller 400 can actively adjust the braking torque output by the braking motor in the electromechanical braking device 210 according to the deceleration of the electric vehicle 10 detected by the inertial measurement unit 150, so as to realize the function of relieving the forward tilt during braking of the electric vehicle 10.

[0054] In one embodiment, still as Figure 2 shown, the rotational speed measurement unit 140 and the inertial measurement unit 150 are communicatively connected to the controller 400 through the braking system 200. Of course, the rotational speed measurement unit 140 and the inertial measurement unit 150 can also be communicatively connected to the controller 400 directly through a communication bus or through the drive system 100.

[0055] The braking system 200 includes a plurality of electromechanical braking devices 210. The controller 400 can control the braking torque output by the braking motor of the electromechanical braking device 210 according to the braking pedal stroke. Among them, the braking pedal stroke is the physical stroke when the driver actively steps on the braking pedal or the electronic stroke signal of the braking pedal output by the autonomous driving system.

[0056] Figure 3 This is a schematic diagram of the braking system provided by the embodiment of the present application. As Figure 3 shown, the electric vehicle 10 includes four wheels 240. The braking system 200 generally includes four electromechanical braking devices 210. The four electromechanical braking devices 210 are respectively used to brake the four wheels 240 of the electric vehicle 10. Each electromechanical braking device 210 is used to brake one wheel 240 of the electric vehicle 10.

[0057] In one embodiment, the two wheels 240 corresponding to the front axle 220 of the electric vehicle 10 are the left front wheel FL and the right front wheel FR, and the two wheels 240 corresponding to the rear axle 230 of the electric vehicle 10 are the left rear wheel RL and the right rear wheel RR. Two electromechanical braking devices 210 are respectively used to brake the left front wheel FL and the right front wheel FR of the electric vehicle 10, and the other two electromechanical braking devices 210 are respectively used to brake the left rear wheel RL and the right rear wheel RR of the electric vehicle 10.

[0058] As Figure 3As shown, the electric vehicle 10 includes one or more controllers 400. Among them, after the driver steps on the brake pedal or the autonomous driving system automatically outputs an electronic travel signal of the brake pedal, the controller 400 sends a brake signal to the electromechanical brake device 210 to control the brake motor in the electromechanical brake device 210 to output a braking torque, thereby braking the corresponding wheel. In the embodiment of the present application, each controller 400 is used to output a brake signal to control one or more electromechanical brake devices 210.

[0059] In one embodiment, the electromechanical braking system 200 includes one controller 400 and four electromechanical brake devices 210. After the driver steps on the brake pedal, the controller 400 controls the four electromechanical brake devices 210 to brake the four wheels 240 of the electric vehicle 10 respectively.

[0060] In one embodiment, the electromechanical braking system 200 includes two controllers 400 and four electromechanical brake devices 210. After the driver steps on the brake pedal, one controller 400 controls two electromechanical brake devices 210 to brake the two front wheels of the electric vehicle 10, and the other controller 400 controls the other two electromechanical brake devices 210 to brake the two rear wheels of the electric vehicle 10.

[0061] In one embodiment, the electromechanical braking system 200 includes four controllers 400 and four electromechanical brake devices 210. After the driver steps on the brake pedal, the four controllers 400 respectively control the four electromechanical brake devices 210 to brake the four wheels of the electric vehicle.

[0062] In one embodiment, when the electric vehicle 10 brakes, the drive motor 120 can also generate a torque opposite to the rotation direction of the wheel during the rotation of the wheel, thereby performing regenerative braking. Among them, the torque output by the drive motor 120 during regenerative braking and opposite to the rotation direction of the wheel will decrease as the vehicle speed decreases, so that the deceleration of the electric vehicle 10 gradually decreases. In addition, when the vehicle speed of the electric vehicle 10 decreases, the wind resistance of the electric vehicle 10 etc. will also decrease, so that the deceleration of the electric vehicle 10 decreases.

[0063] Figure 4 This is a schematic diagram of an electromechanical brake device provided by an embodiment of the present application. The electromechanical brake device 210 includes a wheel-end controller 211, a brake motor 212 and an actuator 213. As Figure 4 shown, the wheel-end controller 211 is used to receive the brake signal output by the controller 400 and to output a control signal to control the brake motor 212. The brake motor 212 is used to output a braking torque to drive the actuator 213. The actuator 213 is used to drive the caliper to clamp the brake disc of a corresponding wheel according to the braking torque output by the brake motor 212.

[0064] In one embodiment, the wheel-end controller 211 in the electro-mechanical braking device 210 includes the controller 400 in the braking system 200.

[0065] In one embodiment, the above-mentioned controller 400 is the central controller in the electric vehicle 10, the vehicle control unit (VCU), or the domain control unit (DCU) in the electric vehicle 10.

[0066] During the driving of the electric vehicle 10, after the driver actively steps on the brake pedal to change the physical stroke of the brake pedal or the automatic driving system automatically outputs an electronic stroke signal of the brake pedal to indicate the brake pedal stroke, the controller 400 outputs a brake control signal to the electro-mechanical braking device 210 according to the corresponding brake pedal stroke to control the brake motor in the electro-mechanical braking device 210 to output a braking torque, so as to decelerate the electric vehicle 10. The greater the brake pedal stroke, the greater the braking torque output by the brake motor, the greater the deceleration of the electric vehicle, and the faster the vehicle speed of the electric vehicle 10 drops, resulting in a more serious forward tilt of the passengers when the electric vehicle stops. Among them, the forward tilt refers to the passengers tilting in the traveling direction of the electric vehicle. The forward tilt direction during forward driving is the head direction of the vehicle. The forward tilt direction during reverse driving is the tail direction of the vehicle.

[0067] When the braking mode of the electric vehicle 10 is emergency braking, the braking efficiency and safety of the electric vehicle 10 should be given priority. That is to say, when the braking mode of the electric vehicle 10 is emergency braking, the controller 400 needs to control the brake motor in the electro-mechanical braking device 210 to output the braking torque indicated by the brake pedal stroke to make the electric vehicle stop more quickly, without considering too much the forward tilt of the passengers caused by excessive deceleration.

[0068] When the braking mode of the electric vehicle 10 is non-emergency braking, the braking comfort and driving experience of the electric vehicle 10 should be considered. That is to say, the deceleration of the electric vehicle 10 at the end of braking should be reduced as much as possible, so as to relieve the forward tilt of the passengers. The vehicle braking forward tilt relief method provided by the embodiments of the present application actively controls the braking torque output by the electro-mechanical braking device 210 to be less than the braking torque indicated by the brake pedal stroke at the end of non-emergency braking, thereby further reducing the deceleration of the electric vehicle and relieving the forward tilt of the passengers, improving the comfort during braking at the end of non-emergency braking.

[0069] In one embodiment, when the travel of the brake pedal increases at the end of braking of the electric vehicle 10 during non-emergency braking, the braking torque output by the electromechanical braking device 210 can remain unchanged or the braking torque output by the electromechanical braking device 210 increases while still being less than the braking torque indicated by the travel of the brake pedal, so as to adjust the braking torque according to actual needs while performing comfortable braking.

[0070] In one embodiment, when the braking distance of the electric vehicle 10 is too long, the electromechanical braking device 210 increases the output braking torque to stop the electric vehicle more quickly and avoid too long braking distance of the electric vehicle.

[0071] In one embodiment, when the travel of the brake pedal increases at an excessive rate of change, the braking torque output by the electromechanical braking device 210 is equal to the braking torque indicated by the travel of the brake pedal. The fact that the travel of the brake pedal increases at an excessive rate of change indicates that the electric vehicle 10 needs to stop as soon as possible. At this time, the electromechanical braking device 210 outputs the braking torque indicated by the travel of the brake pedal, which can stop the vehicle in time and avoid causing safety accidents.

[0072] In one embodiment, when the electric vehicle 10 performs non-emergency braking on a slope, the braking torque output by the electromechanical braking device 210 also needs to be adaptively adjusted according to the slope of the road surface and the driving direction of the electric vehicle 10, so as to offset the influence of the weight of the electric vehicle 10 on the deceleration of the electric vehicle 10.

[0073] In one embodiment, when the electric vehicle 10 performs non-emergency braking under a turning condition, the braking torque output by the electromechanical braking device 210 on the turning side should be greater than the braking torque output by the electromechanical braking device 210 on the other side, so as to provide a torque for assisting steering for the electric vehicle 10 and help the electric vehicle 10 turn faster.

[0074] To facilitate understanding of the vehicle braking forward tilt mitigation method, controller and electric vehicle provided in the embodiments of the present application. The vehicle braking forward tilt mitigation method, controller and electric vehicle provided in the embodiments of the present application will be described below in conjunction with the first moment t1, second moment t2, third moment t3, fourth moment t4, fifth moment t5, sixth moment t6 and seventh moment t7 during the braking process of the electric vehicle.

[0075] During the process of the electric vehicle 10 performing non-emergency braking, if the deceleration of the electric vehicle 10 is greater than or equal to the first preset deceleration a1 and / or the vehicle speed of the electric vehicle is greater than the first preset vehicle speed V1, it indicates that the electric vehicle 10 is not at the end of braking. During the braking process of the electric vehicle 10, if the deceleration of the electric vehicle 10 is less than or equal to the first preset deceleration a1 and the vehicle speed of the electric vehicle is less than the first preset vehicle speed V1, it indicates that the electric vehicle 10 is at the end of braking.

[0076] During the driving of the electric vehicle 10, after the driver actively steps on the brake pedal to output an electronic stroke signal of the brake pedal or the autonomous driving system automatically outputs an electronic stroke signal of the brake pedal, if the braking torque output by the electro-mechanical braking device 210 causes the deceleration of the electric vehicle 10 to be greater than 0.5g, it indicates that the electric vehicle is performing an emergency braking. If the braking torque output by the electro-mechanical braking device 210 causes the deceleration of the electric vehicle 10 to be in the range of 0.1g to 0.5g, it indicates that the electric vehicle 10 is performing non-emergency braking. Wherein, g represents the acceleration due to gravity. In addition, when the electric vehicle 10 starts to perform non-emergency braking, the braking torque output by the electro-mechanical braking device 210 is equal to the braking torque indicated by the brake pedal stroke.

[0077] At the end stage of braking when the electric vehicle 10 is driving, at the first moment t1, when the deceleration of the electric vehicle 10 is less than or equal to the first preset deceleration a1 and the vehicle speed of the electric vehicle 10 is less than or equal to the first preset vehicle speed V1, for example, the first preset deceleration a1 is 4m / s 2 and the first preset vehicle speed V1 is 12km / h, the controller 400 controls the electro-mechanical braking device 210 to output the first braking torque T1, and the first braking torque T1 is less than the braking torque indicated by the brake pedal stroke of the electric vehicle 10 at the first moment t1.

[0078] Figure 5 It is a schematic diagram of the braking control process of the electric vehicle provided by the embodiment of the present application.

[0079] As Figure 5 shown, in one embodiment, at the first moment t1 during the non-emergency braking of the electric vehicle 10, when the deceleration of the electric vehicle 10 is less than or equal to the first preset deceleration a1 and the vehicle speed of the electric vehicle 10 is less than or equal to the first preset vehicle speed V1, it indicates that the electric vehicle 10 is at the end stage of braking. At this time, keeping the braking torque output by the electro-mechanical braking device 210 unchanged when the brake pedal stroke remains unchanged will cause the deceleration of the electric vehicle 10 to suddenly change from a certain value to zero when it stops, resulting in a large forward tilt amplitude of the driver and passengers. Figure 5 In the vehicle speed and deceleration, the positive and negative signs represent the driving direction, with forward driving being positive and reverse driving being negative. The dotted lines in the change trends of the vehicle speed and deceleration represent the change trends when the braking forward tilt mitigation method of the embodiment of the present application is not adopted.

[0080] Among them, the above-mentioned first braking torque T1, first preset deceleration a1, and first preset vehicle speed V1 are calibrated values set according to the actual road conditions and vehicle conditions. The first braking torque T1, first preset deceleration a1, and first preset vehicle speed V1 can be calibrated according to various parameters including the vehicle speed of the electric vehicle, the weight of the electric vehicle, the road surface adhesion coefficient, the road surface gradient, and the steering wheel angle. In addition, the above-mentioned first braking torque T1, first preset deceleration a1, and first preset vehicle speed V1 can be further calibrated according to different vehicle models, which will not be elaborated in the embodiments of the present application.

[0081] In the embodiment of the present application, at the end of non-emergency braking, the controller 400 can actively reduce the braking torque output by the electromechanical braking device 210 to appropriately reduce the deceleration of the electric vehicle 10, so that the speeds of the vehicle body and the chassis can be synchronized, thereby reducing the forward inclination amplitude of the driver and passengers.

[0082] In one embodiment, when the controller 400 controls the electromechanical braking device 210 to output the first braking torque T1, it can rapidly decrease from the braking torque indicated by the brake pedal stroke at the first moment t1 to the first braking torque T1 or gradually decrease from the braking torque indicated by the brake pedal stroke at the first moment t1 to the first braking torque T1. The embodiments of the present application do not make specific limitations on this. In addition, the first braking torque T1 can also gradually decrease with the increase of the braking time, so that the deceleration can be reduced more smoothly.

[0083] When the deceleration of the electric vehicle 10 is too large, it indicates that the electric vehicle 10 needs to be braked to a stop in time. At this time, for safety considerations, the controller 400 in the electric vehicle 10 needs to control the braking motor 212 in the electromechanical braking device 210 to output the braking torque indicated by the brake pedal stroke. When the deceleration of the electric vehicle is too small, the controller 400 controlling the braking motor 212 in the electromechanical braking device 210 to output the braking torque indicated by the brake pedal stroke will not cause the forward inclination of the driver and passengers. At this time, the electromechanical braking device 210 does not need to control the output braking torque to be less than the braking torque indicated by the brake pedal stroke.

[0084] In one embodiment, in order to more effectively improve the comfort of the driver and passengers during non-emergency braking, when the deceleration of the electric vehicle 10 is less than or equal to the first preset deceleration a1 and greater than a relatively small deceleration, the controller 400 controls the braking torque output by the braking motor 212 in the electromechanical braking device 210 to be less than the braking torque indicated by the brake pedal stroke. For example, when the deceleration of the electric vehicle 10 is in the range of [0.05g, 0.3g], the controller 400 controls the braking torque output by the braking motor 212 in the electromechanical braking device 210 to be less than the braking torque indicated by the brake pedal stroke. Additionally, in order to ensure the safety of the electric vehicle 10, when the speed of the electric vehicle 10 is too high, it is necessary to control the braking motor 212 in the electromechanical braking device 210 to output the braking torque indicated by the brake pedal stroke. Therefore, the speed of the electric vehicle 10 needs to be relatively low to control the braking torque output by the braking motor 212 in the electromechanical braking device 210 to be less than the braking torque indicated by the brake pedal stroke. For example, when the speed of the electric vehicle 10 is less than 12 km / h, the above strategy is executed.

[0085] It should be understood that the above-mentioned deceleration value range and vehicle speed threshold are only an exemplary implementation manner provided by this application. During specific implementation, the deceleration value range and vehicle speed threshold can also be calibrated according to the actual road conditions and vehicle conditions, and will not be elaborated in this embodiment of this application.

[0086] Still as Figure 5 shown, after the first moment t1, the brake pedal stroke of the electric vehicle 10 increases. At the second moment t2 after the first moment t1, when the speed of the electric vehicle 10 is less than or equal to the second preset vehicle speed V2, the controller 400 controls the electromechanical braking device 210 to output a second braking torque T2, and this second braking torque T2 is equal to the braking torque indicated by the brake pedal stroke at the second moment t2. The second preset vehicle speed V2 is less than the first preset vehicle speed V1. Among them, from the first moment t1 to the second moment t2, the brake pedal stroke of the electric vehicle 10 increases, and the braking torque output by the controller 400 to control the electromechanical braking device 210 is still less than the braking torque indicated by the brake pedal stroke at the corresponding moment (as shown by the dashed line in Figure 5 ).

[0087] In the embodiment of the present application, the second preset vehicle speed V2 is set to a very low vehicle speed, and the second preset vehicle speed V2 is usually less than the first preset vehicle speed V1. For example, the first preset vehicle speed V1 is 12 km / h and the second preset vehicle speed V2 is 1 km / h. When the vehicle speed of the electric vehicle 10 is less than or equal to the second preset vehicle speed V2 at the second moment t2, it indicates that the vehicle speed has been relatively low and the forward tilt amplitude of the vehicle body is also very small. At this time, for braking safety, the controller 400 actively controls the braking torque output by the electromechanical braking device 210 at the second moment t2 to be equal to the braking torque indicated by the brake pedal stroke, which can stop the electric vehicle 10 in time while alleviating the forward tilt of the driver and passengers. Among them, because the drive motor 120 will output a torque opposite to the rotation direction of the wheels during braking to perform regenerative braking on the electric vehicle, the deceleration of the electric vehicle 10 will gradually decrease.

[0088] It should be understood that the first preset vehicle speed V1 and the second preset vehicle speed V2 need to be calibrated according to the specific road conditions and vehicle conditions during actual implementation, and the embodiment of the present application does not make specific numerical limitations on this.

[0089] In one embodiment, after the second moment t2, the electric vehicle 10 is still in the driving condition, and when the steering angle of the steering wheel of the electric vehicle 10 turns to the left by more than the first preset angle α at the fifth moment t5 after the second moment t2, such as setting α to 3°, the controller 400 controls the braking torque output by the electromechanical braking device 210 on the left side of the electric vehicle 10 to be greater than the braking torque output by the electromechanical braking device 210 on the right side.

[0090] When the steering angle of the steering wheel of the electric vehicle 10 turns to the left by more than the first preset angle α (such as 3°) at the fifth moment t5 after the second moment t2, it indicates that the electric vehicle 10 needs to turn to the left. At this time, when the braking torque output by the electromechanical braking device 210 on the left side (i.e., the left front wheel FL and the left rear wheel RL) of the electric vehicle 10 is the same as the braking torque output by the electromechanical braking device 210 on the right side (i.e., the right front wheel FR and the right rear wheel RR), it will cause the electric vehicle 10 to turn slowly according to the steering angle of the front wheels, resulting in a low steering efficiency of the electric vehicle 10.

[0091] Still as Figure 5 shown, at the moment t after the second moment t2 21 the vehicle speed of the electric vehicle 10 drops to 0, t 21When the electric vehicle 10 is traveling at a lower speed after a certain moment, the steering angle of the steering wheel of the electric vehicle 10 turning to the left is greater than the first preset angle α, and the controller 400 controls the braking torque output by the electromechanical braking device 210 on the left side (i.e., the left front wheel FL and the left rear wheel RL) of the electric vehicle 10 to be greater than the braking torque output by the electromechanical braking device 210 on the right side (i.e., the right front wheel FR and the right rear wheel RR) according to the brake pedal travel.

[0092] In the embodiment of the present application, when the steering angle of the steering wheel of the electric vehicle 10 turning to the left is greater than the first preset angle α at the fifth moment t5 after the second moment t2, the controller 400 actively controls the braking torque output by the electromechanical braking device 210 on the left side to be greater than the braking torque output by the electromechanical braking device 210 on the right side, which can provide an auxiliary steering torque for the electric vehicle 10, thereby helping the electric vehicle 10 to complete the steering faster.

[0093] Furthermore, when the electric vehicle 10 brakes, the braking torques output by the electromechanical braking devices 210 of the two front wheels and the braking torques output by the electromechanical braking devices 210 of the two rear wheels are usually proportionally distributed so that the braking torques output by the electromechanical braking devices 210 of the two front wheels are different from the braking torques output by the electromechanical braking devices 210 of the two rear wheels. For example, when the electric vehicle 10 brakes during forward travel, since the center of gravity of the electric vehicle 10 will shift forward, the braking torque output by the electromechanical braking devices 210 of the two front wheels is greater than the braking torque output by the electromechanical braking devices 210 of the two rear wheels. When the electric vehicle 10 brakes during reverse travel, since the center of gravity of the electric vehicle 10 will shift backward, the braking torque output by the electromechanical braking devices 210 of the two front wheels is less than the braking torque output by the electromechanical braking devices 210 of the two rear wheels.

[0094] Therefore, during the process of controlling the braking torque output by the electromechanical braking device 210 to be less than the braking torque indicated by the brake pedal travel when the electric vehicle 10 brakes, the braking torques output by the electromechanical braking devices 210 of the two front wheels and the braking torques output by the electromechanical braking devices 210 of the two rear wheels also need to meet the above requirements in order to perform comfortable braking on the electric vehicle 10 more smoothly.

[0095] Based on the same principle, when the steering angle of the steering wheel of the electric vehicle 10 turning to the left is greater than the first preset angle α before the end of non-emergency braking, the controller 400 can also control the braking torque output by the electromechanical braking device 210 on the left side to be greater than the braking torque output by the electromechanical braking device 210 on the right side, thereby helping the electric vehicle 10 to complete the steering faster.

[0096] It should be noted that when the electric vehicle 10 is steering, the controller 400 controls the electro-mechanical braking devices 210 on the left and right sides to output braking torques. It can be triggered by the braking stroke in cooperation with the steering angle, or can be triggered solely by the steering angle, that is, the braking stroke is zero. The braking torques output by the electro-mechanical braking devices 210 on the left and right sides only need to be maintained within a certain difference range to assist in steering, which is specifically generated according to the steering calibration of the electric vehicle 10 and there is no fixed value.

[0097] In one embodiment, after the fifth moment t5, the electric vehicle 10 is in a reverse braking condition. And when at the sixth moment t6 after the fifth moment t5, the deceleration of the electric vehicle 10 is less than or equal to the third preset deceleration a3 and the vehicle speed of the electric vehicle 10 is less than the third preset vehicle speed V3, the controller 400 controls the third braking torque T3 output by the electro-mechanical braking device 210. The third braking torque T3 is less than the braking torque indicated by the braking pedal stroke at the sixth moment t6 and greater than the first braking torque T1.

[0098] Still as Figure 5 shown, after the fifth moment t5, at the moment t 51 the vehicle speed of the electric vehicle 10 decreases to zero and after the steering wheel returns to the straight position, it starts to reverse. After the moment t 51 and after the moment t 52 when the driver steps on the braking pedal or the automatic driving system outputs an electronic braking pedal stroke signal, the braking torque output by the controller 400 controlling the electro-mechanical braking device 210 is equal to the braking torque indicated by the corresponding braking pedal stroke. After the moment t 52 and at the sixth moment t6 after that, when the deceleration of the electric vehicle 10 is less than or equal to the third preset deceleration a3 and the vehicle speed of the electric vehicle 10 is less than the third preset vehicle speed V3, the controller 400 controls the third braking torque T3 output by the electro-mechanical braking device 210.

[0099] That the deceleration of the electric vehicle 10 at the sixth moment t6 is less than or equal to the third preset deceleration a3 and the vehicle speed of the electric vehicle 10 is less than the third preset vehicle speed V3 indicates that the electric vehicle 10 is at the end stage of non-emergency braking. At this time, if the braking torque output by the electro-mechanical braking device 210 remains unchanged when the braking pedal stroke remains unchanged, it will cause the deceleration of the electric vehicle 10 to suddenly change from a certain value to zero when it stops, resulting in a relatively large forward tilt amplitude of the driver and passengers.

[0100] In the embodiment of the present application, when the electric vehicle 10 is in a reverse braking condition, at the end stage of non-emergency braking, the controller 400 can also actively reduce the braking torque output by the electro-mechanical braking device 210 to appropriately reduce the deceleration of the electric vehicle 10, so that the speeds of the vehicle body and the chassis can be kept synchronized, thereby reducing the forward tilt amplitude of the driver and passengers.

[0101] In addition, during reverse driving, the driver has a poor field of vision. Therefore, the third braking torque T3 output by the electro-mechanical braking device 210 is greater than the first braking torque T1 for comfortable braking during forward driving, so as to stop the electric vehicle 10 more quickly and avoid safety accidents caused by too long braking distance of the electric vehicle. In addition, the third preset deceleration a3 can also be appropriately greater than the first preset deceleration a1, and the third preset vehicle speed V3 can also be appropriately greater than the first preset vehicle speed V1.

[0102] Of course, when braking during reverse driving and the distance between the traveling direction of the electric vehicle 10 and other obstacles is large, the third braking torque T3 can also be equal to the first braking torque T1 to improve the riding experience.

[0103] It should be understood that the above-mentioned third preset deceleration a3 can be set according to actual needs from the perspectives of vehicle safety and riding experience, and the embodiments of the present application do not make specific limitations on this.

[0104] In one embodiment, after the sixth moment t6, at the seventh moment t7, the deceleration of the electric vehicle 10 is less than or equal to the fourth preset deceleration a4. For example, the fourth preset deceleration a4 is set to 1.5 m / s 2 , and the controller 400 controls the braking torque output by the electro-mechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke at the seventh moment t7.

[0105] Still as Figure 5 shown, after the sixth moment t6, at the seventh moment t7, the deceleration of the electric vehicle 10 being less than or equal to the fourth preset deceleration a4 indicates that the electric vehicle 10 is approaching a stop. At this time, for braking safety, it is necessary to prevent the braking distance of the electric vehicle 10 from being too long. In the embodiments of the present application, the controller 400 actively controls the braking torque output by the electro-mechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke at the seventh moment t7, which can stop the electric vehicle 10 in time while alleviating the forward tilt of the passengers and prevent the braking distance of the electric vehicle 10 from being too long.

[0106] In one embodiment, still as Figure 5 shown, at any moment between the first moment t1 and the second moment t2, the controller 400 can control the braking torque output by the electro-mechanical braking device 210 to be equal to the first braking torque T1.

[0107] After the first moment t1, an increase in the brake pedal travel indicates that the electromechanical braking device 210 needs to output a greater braking torque. However, since it is the end stage of non-emergency braking, the braking torque output by the electromechanical braking device 210 can keep the first braking torque T1 unchanged to stop the vehicle. Therefore, at any moment between the first moment t1 and the second moment t2, the controller 400 can control the braking torque output by the electromechanical braking device 210 to be equal to the first braking torque T1, which simplifies the output control of the braking torque and is conducive to the realization of the control method.

[0108] When the brake pedal travel increases after the first moment t1, keeping the braking torque output by the electromechanical braking device 210 unchanged at the first braking torque T1 may give the driver a feeling that the vehicle cannot be braked.

[0109] In one embodiment, at any moment between the first moment t1 and the second moment t2, the controller 400 controls the braking torque output by the electromechanical braking device 210 to be greater than the first braking torque T1 and less than the braking torque indicated by the brake pedal travel at the corresponding same moment. Among them, at any moment between the first moment t1 and the second moment t2, the braking torque output by the electromechanical braking device 210 is less than the second braking torque T2.

[0110] Based on this, the output of the braking torque can be adjusted according to the needs of the ride feeling, optimizing the deceleration control of the whole vehicle, and further ensuring the braking comfort.

[0111] Figure 6 Another schematic diagram of the braking control process of the electric vehicle provided by the embodiment of the present application. As Figure 6 shown, when the brake pedal travel increases after the first moment t1 and the rate of increase in the brake pedal travel is less than the preset rate (that is, the increase slope of the brake pedal is greater than the preset slope), between the first moment t1 and the second moment t2, the controller 400 controls the braking torque output by the electromechanical braking device 210 to gradually increase, so that the deceleration control of the whole vehicle changes linearly, further ensuring the braking comfort. Among them, the rate of increase in the brake pedal travel being less than the preset rate indicates that the electric vehicle 10 does not need to perform emergency braking. Therefore, the braking torque output by the electromechanical braking device 210 can still be controlled to be less than the braking torque indicated by the brake pedal travel for comfortable braking.

[0112] Still as Figure 6 shown, when the brake pedal travel increases between the sixth moment t6 and the seventh moment t7 and the rate of increase in the brake pedal travel is less than the preset rate (that is, the increase slope of the brake pedal is greater than the preset slope), between the sixth moment t6 and the seventh moment t7, the controller 400 controls the braking torque output by the electromechanical braking device 210 to remain unchanged, so that the whole vehicle can decelerate more smoothly.

[0113] In one embodiment, when the driving distance of the electric vehicle 10 from the first moment t1 to the third moment t3 after the first moment t1 and before the second moment t2 is greater than the first preset distance S1, the controller 400 controls the electromechanical braking device 210 to increase the output braking torque.

[0114] Figure 7 Another schematic diagram of the braking control process of the electric vehicle provided by the embodiment of the present application is as follows. Figure 7 As shown in the figure, the driving distance of the electric vehicle 10 from the first moment t1 to the third moment t3 is greater than the first preset distance S1, indicating that the braking distance of the electric vehicle 10 is too long. At this time, keeping the braking torque output by the electromechanical braking device 210 unchanged will excessively increase the braking distance and easily lead to safety accidents. Therefore, when the braking distance is too large, the controller 400 actively controls the electromechanical braking device 210 to increase the output braking torque, which can decelerate the electric vehicle 10 to a stop faster and avoid safety accidents caused by excessive increase in the braking distance.

[0115] Among them, the controller 400 can calculate the theoretical driving distance of the electric vehicle 10 at each moment during the end stage of braking when comfort braking is not performed according to the vehicle speed, weight, wheel diameter of the electric vehicle 10, and the output characteristics of the braking torque output by the electromechanical braking device 210. This theoretical driving distance can be used as a reference value when judging that the braking distance of the electric vehicle 10 is too long, that is, the above-mentioned first preset distance S1. When the driving distance of the electric vehicle 10 is greater than the first preset distance S1 within the same time after triggering comfort braking during the braking process of the electric vehicle 10, it indicates that the braking distance of the electric vehicle 10 is too long, and the controller 400 needs to control the electromechanical braking device 210 to increase the output braking torque.

[0116] In one embodiment, when the controller 400 controls the electromechanical braking device 210 to increase the output braking torque, it can also adjust the rate at which the electromechanical braking device 210 increases the output braking torque according to the driving distance of the electric vehicle 10. For example, when the driving distance of the electric vehicle 10 from the first moment t1 to the third moment t3 is greater than the first preset distance S1 but less than the second preset distance S2, the controller 400 controls the electromechanical braking device 210 to increase the output braking torque at the first rate. When the driving distance of the electric vehicle 10 from the first moment t1 to the third moment t3 is greater than the second preset distance S2, the controller 400 controls the electromechanical braking device 210 to increase the output braking torque at the second rate. Among them, the second rate is greater than the first rate. It should be noted that the above-mentioned first preset distance S1 and second preset distance S2 are not fixed values, but a series of calculated values set according to braking characteristics and working conditions.

[0117] In the above manner, during the end stage of braking in non-emergency braking, when the driving distance of the electric vehicle 10 is too large, the braking torque output by the electromechanical braking device 210 can be adjusted more quickly according to the driving distance, so as to perform braking more safely.

[0118] It should be understood that the above method of controlling the electromechanical braking device 210 to increase the output braking torque is only an exemplary implementation manner provided by the embodiments of the present application. During specific implementation, the rate at which the electromechanical braking device 210 increases the output braking torque can be calibrated according to actual needs, and the embodiments of the present application do not make specific limitations on this.

[0119] In one embodiment, when the deceleration of the electric vehicle 10 at the fourth moment t4 after the first moment t1 and before the second moment t2 is less than the second preset deceleration a2, for example, when the second preset deceleration a2 is set to 1.2 m / s 2 , the controller 400 controls the braking torque output by the electromechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke at the fourth moment t4, and the second preset deceleration a2 is less than the first preset deceleration a1.

[0120] Figure 8 Another schematic diagram of the braking control process of the electric vehicle provided by the embodiments of the present application. As Figure 8 shown, when the deceleration of the electric vehicle 10 at the fourth moment t4 after the first moment t1 and before the second moment t2 is less than the second preset deceleration a2, it indicates that the deceleration of the electric vehicle 10 is very small. At this time, the braking torque output by the electromechanical braking device 210 will not cause the driver and passengers to lean forward. Therefore, the controller 400 can control the braking torque output by the electromechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke at the fourth moment t4, so as to decelerate the electric vehicle 10 to a stop more quickly and prevent the braking distance of the electric vehicle 10 from being too long.

[0121] Among them, considering the poor vision during reverse driving, for the braking safety during reverse driving, the above-mentioned fourth deceleration a4 is greater than the above-mentioned second preset deceleration a2. It should be noted that the fourth preset deceleration a4 being greater than the second preset deceleration a2 means that the absolute value of the fourth preset deceleration a4 is greater than the absolute value of the second preset deceleration a2.

[0122] In one embodiment, when the vehicle speed of the electric vehicle 10 at the first moment t1 is greater than the first preset vehicle speed V1, the controller 400 controls the braking torque output by the electromechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke of the electric vehicle 10 at the first moment t1.

[0123] In an embodiment of the present application, when the vehicle speed of the electric vehicle 10 is greater than the first preset vehicle speed V1, it indicates that the electric vehicle 10 is not in the final stage of braking. At this time, the braking torque output by the electromechanical braking device 210 is equal to the braking pedal stroke of the electric vehicle 10, which can reduce the vehicle speed of the electric vehicle 10 faster and avoid increasing the braking distance of the electric vehicle 10.

[0124] In one embodiment, when the change rate of the braking pedal stroke at any time between the first moment t1 and the second moment t2 is greater than the first preset change rate, the controller 400 controls the braking torque output by the electromechanical braking device 210 to be equal to the braking torque indicated by the braking pedal stroke at the first moment.

[0125] In an embodiment of the present application, when the change rate of the braking pedal stroke is too large at any time between the first moment t1 and the second moment t2, it indicates that an emergency occurs between the first moment t1 and the second moment t2. For example, there are pedestrians, vehicles or other obstacles in the traveling direction, the driver will quickly step on the braking pedal or the automatic driving system will increase the electronic stroke signal of the braking pedal. At this time, the change rate of the braking pedal stroke is large, and the electric vehicle 10 needs to stop quickly to avoid safety accidents.

[0126] Therefore, the controller 400 controls the electromechanical braking device 210 to output the braking torque indicated by the braking pedal stroke, thereby interrupting the comfort braking process to stop the vehicle faster and avoid safety accidents.

[0127] It should be understood that the above first preset change rate can be a calibration value set according to the road conditions and vehicle conditions of the electric vehicle 10 traveling, and the present application embodiment does not specifically limit its value.

[0128] In one embodiment, when the braking torque output by the electromechanical braking device 210 between the first moment t1 and the second moment t2 is restored to the braking torque indicated by the braking pedal stroke at the first moment, the torque can be increased at different torque increasing rates according to the change rate of the braking pedal stroke. For example, when the change rate of the braking pedal stroke is greater than the first preset change rate but less than the second preset change rate, the torque is increased to the braking torque indicated by the braking pedal stroke at the first moment at the first rate. When the change rate of the braking pedal stroke is greater than the second preset change rate, the torque is increased to the braking torque indicated by the braking pedal stroke at the first moment at the second rate. Among them, the first rate is less than the second rate.

[0129] Based on this, the controller 400 can adjust the torque increasing rate according to the change rate of the braking pedal stroke so as to reduce the speed of the electric vehicle 10 faster while improving the driving and riding experience.

[0130] In one embodiment, based on the same technical principle, when the change rate of the brake pedal stroke at the first moment t1 is greater than the first preset change rate, the controller 400 can also control the braking torque output by the electromechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke at the first moment. This is not elaborated in the embodiments of the present application.

[0131] In one embodiment, when the electric vehicle 10 is in an uphill working condition and the road surface gradient on which the electric vehicle 10 travels is greater than the first preset gradient, the first braking torque T1 is controlled to be inversely proportional to the road surface gradient at the first moment t1. When the electric vehicle 10 is in a downhill working condition and the road surface gradient on which the electric vehicle 10 travels is greater than the second preset gradient, the first braking torque T1 is controlled to be directly proportional to the road surface gradient at the first moment t1. Herein, the first preset gradient and the second preset gradient are the same value, or the first preset gradient and the second preset gradient are different values.

[0132] When the electric vehicle 10 is in an uphill working condition, the weight of the electric vehicle 10 itself will increase the resistance of the electric vehicle 10 going uphill, resulting in an increase in the deceleration of the electric vehicle 10. Among them, the greater the road surface gradient, the greater the resistance generated by the weight of the electric vehicle 10 itself, and the faster the deceleration increases. When the road surface gradient is greater than the first preset gradient at the first moment t1 when the electric vehicle 10 is in an uphill working condition, it indicates that the road surface gradient has a greater impact on the deceleration of the electric vehicle 10. At this time, if the braking torque output by the electromechanical braking device 210 remains unchanged, it will cause the deceleration of the electric vehicle 10 to be too large, thus quickly braking the electric vehicle and causing the passengers to lean forward. Therefore, in the embodiments of the present application, the controller 400 actively reduces the braking torque output by the electromechanical braking device 210 according to the road surface gradient on which the electric vehicle 10 travels in the uphill working condition, so as to more smoothly reduce the deceleration of the electric vehicle 10.

[0133] It should be further noted that the greater the road surface gradient in the downhill working condition, the greater the resistance generated by the weight of the electric vehicle 10 itself. Therefore, when the road surface gradient when the electric vehicle 10 is in an uphill working condition is greater than the first preset gradient, the controller 400 controls the first braking torque T1 to be inversely proportional to the road surface gradient at the first moment t1, that is, the greater the road surface gradient, the smaller the first braking torque T1.

[0134] Based on this, the controller 400 can actively adjust the magnitude of the first braking torque T1 according to the road surface gradient on which the electric vehicle 10 travels when the electric vehicle 10 is in an uphill working condition, so as to better perform comfortable braking on the electric vehicle 10.

[0135] In one embodiment, when the electric vehicle 10 is in a downhill working condition, the weight of the electric vehicle 10 itself will increase the power of the electric vehicle 10 going downhill, resulting in a decrease in the deceleration of the electric vehicle 10. Among them, the greater the slope of the road surface, the greater the power generated by the weight of the electric vehicle 10 itself, and the faster the rate of decrease in deceleration. When the road surface slope of the electric vehicle 10 in the downhill working condition at the first moment t1 is greater than the second preset slope, it indicates that the influence of the road surface slope on the deceleration of the electric vehicle 10 is greater. At this time, if the braking torque output by the electromechanical braking device 210 remains unchanged, it will cause the deceleration of the electric vehicle 10 to decrease too fast, resulting in the electric vehicle 10 surging forward. Therefore, in the embodiment of the present application, when the electric vehicle 10 is in the downhill working condition, at the first moment t1, the electromechanical braking device 210 actively increases the output braking torque according to the road surface slope of the electric vehicle driving, so that the deceleration of the electric vehicle decreases more smoothly.

[0136] It should be further noted that when the electric vehicle 10 is in the downhill working condition, the greater the road surface slope, the greater the power provided by the weight of the electric vehicle 10. Therefore, when the road surface slope is greater than the second preset slope, the controller 400 controls the first braking torque T1 to be proportional to the road surface slope at the first moment t1, that is, the greater the road surface slope, the greater the first braking torque T1.

[0137] Based on this, the controller 400 can actively adjust the magnitude of the first braking torque T1 according to the road surface slope when the electric vehicle 10 is in the downhill working condition, so as to better perform comfortable braking on the electric vehicle 10.

[0138] In one embodiment, in order to better control the deceleration of the electric vehicle 10 more accurately in scenarios such as flat road conditions, uphill conditions, and downhill conditions. The controller 400 can control the braking torque output by the electromechanical braking device 210 according to the calibrated deceleration under various working conditions, so that after the braking torque output by the electromechanical braking device 210 decreases, the electric vehicle 10 can brake according to the calibrated deceleration.

[0139] Furthermore, considering that there will be differences in the control accuracy of the actuator 213 in the electromechanical braking device 210. Therefore, the controller 400 can adaptively adjust the calibrated deceleration under various road conditions according to the control accuracy of the actuator. For example, the target deceleration of the electric vehicle 10 under flat road conditions is a0. The calibrated deceleration of the electric vehicle 10 under flat road conditions is a0*f. Where f is the calibrated value of the compensation coefficient of the actuator.

[0140] In addition, considering that the deceleration of the electric vehicle 10 in uphill and downhill conditions is affected by the weight of the electric vehicle 10 itself. In one embodiment, the calibrated deceleration in the uphill condition can be 2*g0*f. Wherein, g0 represents the gravitational component of the electric vehicle 10 downward along the slope in the uphill condition. The calibrated deceleration in the downhill condition can be (a0 + g0)*f.

[0141] It should be understood that the calculation methods of the decelerations calibrated for the above various road conditions are only an exemplary solution provided by the embodiments of the present application. When specifically implemented, the decelerations calibrated for various road conditions can also be adaptively adjusted in combination with the vehicle speed of the electric vehicle 10, the bumpiness of the road surface, the compression degree of the suspension, etc. The embodiments of the present application do not make specific limitations on this.

[0142] In one embodiment, when the electric vehicle 10 is braking in the uphill or downhill condition, the electric vehicle 10 may experience a situation of slipping. At this time, the controller 400 needs to actively and quickly increase the braking torque output by the electromechanical braking device 210 to prevent the electric vehicle 10 from continuing to slip.

[0143] In one embodiment, when the wheel slip ratio of the electric vehicle 10 is less than the first preset slip ratio, the controller 400 controls the first braking torque T1 to be proportional to the wheel slip ratio at the first moment t1. That is, when the wheel slip ratio is less than the first preset slip ratio, the larger the vehicle slip ratio, the larger the first braking torque T1. When the wheel slip ratio of the electric vehicle 10 is greater than or equal to the first preset slip ratio, the controller 400 controls the braking torque output by the electromechanical braking device 210 to be equal to the braking torque indicated by the brake pedal stroke at the first moment t1.

[0144] When the wheel slip ratio is less than the first preset slip ratio, it indicates that the electric vehicle 10 is driving on a high-adhesion road surface. At this time, the increase in the vehicle slip ratio indicates that the degree of wheel slip is greater, and the electromechanical braking device 210 needs to output a larger braking torque to limit the wheel slip. When the wheel slip ratio of the electric vehicle 10 is greater than or equal to the first preset slip ratio, it indicates that the electric vehicle 10 is driving on a low-adhesion road surface. At this time, it is necessary to quickly limit the degree of wheel slip to prevent the electric vehicle 10 from losing balance.

[0145] In the embodiments of the present application, the controller 400 actively controls the braking torque output by the electromechanical braking device 210 at the first moment t1 according to the wheel slip ratio, which can perform a more comfortable braking on the electric vehicle 10 more smoothly.

[0146] It should be further noted that in one embodiment, when the adhesion coefficient of the road surface suddenly increases from the first moment t1 to the second moment t2, for example, when the electric vehicle 10 drives from a low-adhesion road surface to a high-adhesion road surface, the increase in the friction coefficient between the electric vehicle 10 and the ground will increase the frictional force between the electric vehicle 10 and the ground, thereby increasing the braking force of the electric vehicle 10. At this time, if the braking torque output by the electromechanical braking device 210 remains unchanged, it will cause the deceleration of the electric vehicle 10 to suddenly increase, resulting in discomfort for the driver and passengers. Therefore, correspondingly, when the adhesion coefficient of the road surface suddenly increases at any moment from the first moment t1 to the second moment t2, the controller 400 controls the braking torque output by the electromechanical braking device 210 to be less than the first braking torque T1. Among them, the above control strategy can be triggered when the resolver signal of the electric vehicle suddenly decreases or the vehicle speed suddenly decreases.

[0147] In the embodiment of the present application, when the adhesion coefficient of the road surface suddenly increases at any moment from the first moment t1 to the second moment t2, the controller 400 actively controls the braking torque output by the electromechanical braking device 210 to be less than the first braking torque T1, which can avoid the increase in the deceleration of the electric vehicle 10 due to the increase in the frictional force provided by the road surface, thereby ensuring a more comfortable braking of the electric vehicle 10.

[0148] Based on the same principle, in one embodiment, when the adhesion coefficient of the road surface suddenly decreases from the first moment t1 to the second moment t2, for example, when the electric vehicle 10 drives from a high-adhesion road surface to a low-adhesion road surface, the decrease in the friction coefficient between the electric vehicle 10 and the ground will reduce the frictional force between the electric vehicle 10 and the ground, thereby reducing the braking force of the electric vehicle 10. At this time, if the braking torque output by the electromechanical braking device 210 remains unchanged, it will cause the electric vehicle to lunge forward. Among them, the above control strategy can be triggered when the resolver signal of the electric vehicle suddenly increases or the vehicle speed suddenly increases.

[0149] Therefore, correspondingly, when the adhesion coefficient of the road surface suddenly decreases at any moment from the first moment t1 to the second moment t2, the controller 400 controls the braking torque output by the electromechanical braking device 210 to be greater than the first braking torque T1 and less than the braking torque indicated by the brake pedal stroke. Based on this, when performing a comfortable braking on the electric vehicle 10, it is possible to avoid the electric vehicle 10 lunging forward due to a sudden decrease in the adhesion coefficient.

[0150] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for alleviating forward tilt during braking of a vehicle, characterized in that: The braking forward tilt mitigation method is used to control the electronic mechanical braking device of the vehicle to output a braking torque at the end of braking when the vehicle is traveling, and the braking forward tilt mitigation method includes: At a first moment, the deceleration of the vehicle is less than or equal to a first preset deceleration and the speed of the vehicle is less than or equal to a first preset speed, and the electronic mechanical braking device is controlled to output a first braking torque, which is less than the braking torque indicated by the brake pedal stroke of the vehicle at the first moment.

2. The method for alleviating forward tilt during braking according to claim 1, characterized in that: The braking forward tilt mitigation method further comprises: After the first moment, the brake pedal travel of the vehicle increases, and at a second moment after the first moment, the vehicle speed is less than or equal to a second preset speed, and the electronic mechanical braking device is controlled to output a second braking torque, which is equal to the braking torque indicated by the brake pedal travel at the second moment, wherein the second preset speed is less than the first preset speed.

3. The method for alleviating forward tilt during braking according to claim 2, characterized in that: The braking forward tilt mitigation method further comprises: At any moment between the first moment and the second moment, the braking torque output by the electronic mechanical braking device is controlled to be equal to the first braking torque, or; At any moment between the first moment and the second moment, the braking torque output by the electronic mechanical braking device is controlled to be greater than the first braking torque and less than the braking torque indicated by the brake pedal stroke at the same moment.

4. The method for alleviating forward tilt during braking according to claim 2 or 3, characterized in that: The braking forward tilt mitigation method further comprises: At a third moment after the first moment and before the second moment, the travel distance of the vehicle from the first moment to the third moment is greater than a first preset distance, and the electronic mechanical brake device is controlled to increase the output braking torque.

5. The method for alleviating forward tilt by braking according to any one of claims 2 to 4, characterized in that: The braking forward tilt mitigation method further comprises: At a fourth moment after the first moment and before the second moment, the deceleration of the vehicle is less than or equal to a second preset deceleration, the braking torque output by the electronic mechanical braking device is controlled to be equal to the braking torque indicated by the brake pedal stroke at the fourth moment, and the second preset deceleration is less than the first preset deceleration.

6. The method for alleviating forward tilt during braking according to any one of claims 1 to 5, characterized in that: The braking forward tilt mitigation method further comprises: At the first moment, the vehicle speed is greater than the first preset vehicle speed, and the braking torque output by the electronic mechanical braking device is controlled to be equal to the braking torque indicated by the brake pedal stroke of the vehicle at the first moment.

7. The method for alleviating forward tilt by braking according to any one of claims 2 to 6, characterized in that: The braking forward tilt mitigation method further comprises: At any moment between the first moment and the second moment, the change rate of the brake pedal stroke is greater than a first preset change rate, and the braking torque output by the electronic mechanical brake device is controlled to be equal to the braking torque indicated by the brake pedal stroke at the first moment.

8. The method for alleviating forward tilt during braking according to claim 1, characterized in that: The braking forward tilt mitigation method further comprises: At the first moment, the change rate of the brake pedal stroke is greater than a first preset change rate, and the braking torque output by the electronic mechanical brake device is controlled to be equal to the braking torque indicated by the brake pedal stroke at the first moment.

9. The method for alleviating forward tilt during braking according to any one of claims 1 to 8, characterized in that: The braking forward tilt mitigation method further comprises: The vehicle is in an uphill condition, the slope of the road on which the vehicle is traveling is greater than a first preset slope, and at the first moment, the first braking torque is controlled to be inversely proportional to the road slope; The vehicle is in a downhill condition, the slope of the road on which the vehicle is traveling is greater than a second preset slope, and at the first moment, the first braking torque is controlled to be proportional to the road slope.

10. The method for alleviating forward tilt during braking according to any one of claims 1 to 9, characterized in that: The braking forward tilt mitigation method further comprises: The wheel slip ratio of the vehicle is less than a first preset slip ratio, and at the first moment, the first braking torque is controlled to be proportional to the wheel slip ratio; The wheel slip rate of the vehicle is greater than or equal to the first preset slip rate, and the braking torque output by the electronic mechanical braking device is controlled to be equal to the braking torque indicated by the brake pedal stroke at the first moment at the first moment.

11. The method for alleviating forward tilt by braking according to any one of claims 2 to 10, characterized in that: The braking forward tilt mitigation method further comprises: After the second moment, the vehicle is in a driving condition. At the fifth moment after the second moment, the steering wheel of the vehicle turns left at a angle greater than a first preset angle, and the braking torque output by the electronic mechanical braking device on the left side of the vehicle is controlled to be greater than the braking torque output by the electronic mechanical braking device on the right side.

12. The method for alleviating forward tilt during braking according to claim 11, characterized in that: The braking forward tilt mitigation method further comprises: When the vehicle is in the reverse braking condition after the fifth moment, the deceleration of the vehicle at a sixth moment after the fifth moment is less than or equal to the third preset deceleration and the vehicle speed is less than the third preset speed, and the third braking torque output by the electronic mechanical braking device is controlled, and the third braking torque is less than the braking torque indicated by the brake pedal stroke at the sixth moment and greater than the first braking torque.

13. The method for alleviating forward tilt during braking according to claim 12, characterized in that: The braking forward tilt mitigation method further comprises: At a seventh moment after the sixth moment, the deceleration of the vehicle is less than a fourth preset deceleration, and the braking torque output by the electronic mechanical braking device is controlled to be equal to the braking torque indicated by the brake pedal stroke at the seventh moment.

14. A controller, characterized in that: The controller is used to implement the brake forward tilt relief method described in any one of claims 1 to 13, and the controller is used to communicate with the electronic mechanical braking device of the vehicle and control the brake motor of the electronic mechanical braking device to output the braking torque.

15. A vehicle, characterized in that: The vehicle performs braking control using the braking tilt relief method described in any one of claims 1 to 13.

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