Hybrid vehicle braking control method, device and vehicle

Abstract

This application relates to the field of new energy vehicle technology and provides a hybrid vehicle braking control method, device, and vehicle. The method comprises: when the vehicle is traveling downhill, respectively calculating the predicted speed and safe speed of the vehicle within a preset future time period; determining a target braking method within a preset future time period based on the road conditions and weather ahead of the vehicle; and determining the braking force of the target braking method based on the difference between the predicted speed and the safe speed. This application estimates the safe speed of the vehicle within a preset future time period and adjusts the braking force of the corresponding target braking method based on the road conditions and weather, thereby bringing the vehicle's speed close to the safe speed and improving the safety of the vehicle when traveling downhill.

Description

Technical Field

[0001] The present application relates to the technical field of new energy vehicles, and in particular to a hybrid vehicle braking control method, device and vehicle. Background Art

[0002] New energy vehicles currently use different braking methods than traditional fuel-powered vehicles. In addition to active braking systems, they generally also feature auxiliary braking systems. When braking downhill, relying solely on driver experience can lead to excessive or insufficient speed depending on road conditions and weather, compromising driving safety. Summary of the Invention

[0003] In view of this, the embodiments of the present application provide a hybrid vehicle braking control method, device and vehicle to solve the problem of low safety during braking of the vehicle in a downhill driving scenario.

[0004] A first aspect of an embodiment of the present application provides a hybrid vehicle braking control method, comprising: when the vehicle is traveling downhill, respectively calculating a predicted vehicle speed and a safe vehicle speed for a preset future duration; determining a target braking method for the vehicle for a preset future duration based on the road conditions and weather in front of the vehicle; determining a braking force of the target braking method based on a difference between the predicted vehicle speed and the safe vehicle speed, and braking the vehicle based on the target braking method and the braking force.

[0005] According to a second aspect of an embodiment of the present application, a hybrid vehicle braking control device is provided, comprising: a vehicle speed calculation module, configured to calculate a predicted vehicle speed and a safe vehicle speed for a preset future duration when the vehicle is traveling downhill; a braking strategy module, configured to determine a target braking method for the vehicle for a preset future duration based on the road conditions and weather in front of the vehicle; and a braking control module, configured to determine a braking force of a target braking method based on a difference between the predicted vehicle speed and the safe vehicle speed, so as to brake the vehicle based on the target braking method and the braking force.

[0006] According to a third aspect of an embodiment of the present application, a vehicle is provided, comprising an active braking system, an auxiliary braking system and a controller, wherein the controller comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and wherein the processor implements the steps of the above method when executing the computer program.

[0007] According to a fourth aspect of an embodiment of the present application, a readable storage medium is provided, which stores a computer program. When the computer program is executed by a processor, the steps of the above method are implemented.

[0008] Compared with the prior art, the embodiments of the present application have the following beneficial effects: the hybrid vehicle braking control method calculates the predicted vehicle speed and the safe vehicle speed for a preset time period in the future when the vehicle is traveling downhill; determines the target braking mode of the vehicle for a preset time period in the future according to the road conditions and weather in front of the vehicle; determines the braking force of the target braking mode according to the difference between the predicted vehicle speed and the safe vehicle speed, and brakes the vehicle based on the target braking mode and the braking force, so that the vehicle speed is close to the safe speed, thereby improving the safety of the vehicle when traveling downhill. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0010] Figure 1 This is a flow chart of a hybrid vehicle braking control method provided by an embodiment of the present application;

[0011] Figure 2 This is a schematic diagram of the main forces acting on a car going downhill provided by an embodiment of the present application;

[0012] Figure 3 This is a flow chart of determining a target braking mode within a preset time period in the future, provided by an embodiment of the present application;

[0013] Figure 4 This is a schematic structural diagram of a hybrid vehicle braking control device provided by an embodiment of the present application;

[0014] Figure 5 This is a schematic diagram of the main structure of a car provided by an embodiment of the present application;

[0015] Figure 6 This is a schematic diagram of the system architecture of a car in an application scenario provided by an embodiment of the present application;

[0016] Figure 7 It is a schematic diagram of the structure of the controller in the car provided in the embodiment of the present application. DETAILED DESCRIPTION

[0017] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0018] See Figure 1 In a first embodiment of the present application, a hybrid vehicle braking control method is provided, comprising:

[0019] S101, when the vehicle is traveling downhill, respectively calculating a predicted speed and a safe speed of the vehicle within a preset time period in the future;

[0020] S102, determining a target braking mode for the vehicle within a preset time period in the future based on the road conditions and weather ahead of the vehicle;

[0021] S103, determining a target braking mode and a braking force according to a difference between the predicted vehicle speed and the safe vehicle speed, and braking the vehicle based on the target braking mode and the braking force.

[0022] This embodiment calculates the predicted speed and safe speed estimate of the car within a preset time period in the future, and specifies the target braking method for the preset time period in the future in combination with the road conditions and weather. According to the difference between the predicted speed and the safe speed, the braking force of the corresponding target braking method is adjusted. The car is braked based on the target braking method and braking force, so that the predicted speed of the car within the set time period in the future is close to the safe speed (for example, the absolute value of the difference between the predicted speed and the safe speed is less than a preset threshold), so as to improve the safety of the car driving downhill.

[0023] During the driving process of the vehicle, it is monitored whether the vehicle is in a downhill driving state. If so, the hybrid vehicle braking control method is executed; if not, the hybrid vehicle braking control method is exited.

[0024] Among them, there is no unique way to detect that a car is traveling downhill. For example, an acceleration sensor can be used to measure the acceleration of the car in the direction of gravity. If the acceleration along the direction of the car's forward movement is greater than zero and persists, it is determined that the car is traveling downhill. Alternatively, a gyroscope can be used to detect the car's tilt angle (or pitch angle). When the front end of the car is tilted downward relative to the horizontal plane, it is determined that the car is traveling on a downhill section. For another example, a car positioning system can be combined with elevation data in a geographic information system to enable the car to obtain real-time position corresponding to the road elevation information stored in a map database, calculate the slope change of the road ahead, and if the map data shows that the height of the current section is gradually decreasing, it is determined that the car is on a downhill section. Of course, in practice, other technical means can also be used to detect that a car is traveling downhill, and the embodiments of the present application are not limited to this.

[0025] The future preset duration can be a fixed value or a dynamic value. When the future preset duration is a fixed value, a time length can be set in advance based on fixed operating parameters or standards, such as 3 seconds or 5 seconds. When the future preset duration is a dynamic value, a time length can be determined based on factors such as current road conditions or weather. For example, in rainy or snowy weather or when the road ahead is curved, the future preset duration can be selected as 5 seconds. In non-rainy or snowy weather or when the road ahead is flat, the future preset duration can be selected as 10 seconds.

[0026] In this embodiment, the predicted vehicle speed is an estimated speed over a period of time in the future based on the current vehicle state and physical conditions. Assuming the vehicle's current initial speed is V0, the vehicle's total braking deceleration is a1 (including the combined force of active braking and auxiliary braking), the preset future duration is T, and the downhill slope angle is θ. The formula for calculating the predicted vehicle speed can be:

[0027] V1=V0+(g*sinθ-a1)*T;

[0028] Wherein, V1 represents the predicted speed, g*sinθ is the acceleration component due to gravity, and a1 is the comprehensive braking deceleration of the vehicle, such as the braking deceleration generated by the combined force of active braking and auxiliary braking.

[0029] It should be noted that the above-mentioned calculation formulas for predicted vehicle speed and safe vehicle speed are only examples. In practice, corresponding prediction models can also be constructed based on the physical dynamic model of a car on a downhill slope, including but not limited to prediction models for calculating predicted vehicle speed.

[0030] For example, see Figure 2 , when driving downhill, the forces acting on the car mainly include:

[0031] Gravity G: vertically downward;

[0032] Gravity component G1 (perpendicular to the slope): acts on the wheels, forming positive pressure;

[0033] Gravity component G2 (along the slope): moves downward along the slope, accelerating the car and also acting as a slope assist.

[0034] Friction force Ff: along the slope, preventing sliding;

[0035] Air resistance Fh: Opposite to the direction of motion, resisting the air resistance.

[0036] According to the above force model, the demand driving force of the car FA = Fh + G1 + Ff.

[0037] Specifically, when a car is traveling downhill, gravity plays a significant role in its acceleration. The steeper the slope, the more pronounced the effect of gravity on vehicle speed. Therefore, the vehicle's acceleration can be calculated based on factors such as the slope (or inclination angle), the vehicle's mass, and the acceleration due to gravity, thereby predicting the vehicle's speed for a predetermined time period in the future. Furthermore, considering air resistance and tire rolling resistance, which slow down the increase in vehicle speed, the vehicle's actual acceleration can be calculated based on the balance between gravity, air resistance, rolling resistance, and other resistances (such as road friction). This allows the vehicle's predicted speed to be estimated for a predetermined time period in the future.

[0038] In addition, the safe speed is a safety limit calculated based on environmental factors such as road conditions and weather to ensure vehicle driving safety. Assuming the maximum safe speed allowed by the road is V2, the safe speed can be calculated by combining the slope of the vehicle and the road friction coefficient μ. The safe speed calculation formula is:

[0039] Where g is the acceleration due to gravity, and h is the current slope height difference. In practice, the friction coefficient μ can be determined based on the road surface type and weather conditions. For example, if the road ahead is bumpy and has a corresponding friction coefficient of 0.4, and it's rainy and has a rain impact coefficient of 0.8, then the friction coefficient μ = 0.4 * 0.8 = 0.32.

[0040] In some embodiments, in the above step S101, the safe speed of the car within a preset time period in the future is calculated, including: obtaining the slope data and car driving data of the downhill slope on which the car is traveling; determining the acceleration affected by the slope based on the slope data; determining the acceleration affected by the road condition based on the road condition and the slope data on which the car is traveling downhill; determining the acceleration affected by the weather based on the acceleration affected by the weather and the slope; determining the safe speed of the car within a preset time period in the future based on the acceleration affected by the slope, the acceleration affected by the road condition, the acceleration affected by the weather and the car driving data.

[0041] Specifically, when a car is driving downhill, the acceleration / deceleration effects caused by the road conditions and the deceleration effects caused by weather conditions can be calculated using empirical formulas and coefficient adjustments based on different road conditions and weather conditions.

[0042] Among them, regarding the acceleration / deceleration effect caused by road conditions, different road conditions have different effects on the speed of the car. In this embodiment, road conditions include but are not limited to slopes, curves and potholes, all of which can affect the acceleration or deceleration of the car.

[0043] First, the slope will cause acceleration or deceleration due to gravity, which can be calculated using the following formula:

[0044] a gravity =g×sin(θ);

[0045] Among them, g is the acceleration due to gravity, which is generally taken as 9.8m / s 2 ; θ is the slope angle of the road. A positive slope (downhill) will cause acceleration, and a negative slope (uphill) will cause deceleration.

[0046] Secondly, the curve deceleration effect, the curve will reduce the speed of the car. The curve deceleration can be calculated based on the turning radius R of the car and the lateral acceleration a of the car. curve To calculate, the specific calculation formula is as follows:

[0047]

[0048] Among them, V0 is the current speed of the car, R is the turning radius of the curve. The sharper the curve, the smaller the turning radius R, and the more obvious the deceleration effect.

[0049] Furthermore, the pothole deceleration effect, potholes on the road will cause additional friction and resistance, thereby slowing down the car. Assuming that the impact of potholes can be calculated by the empirical deceleration coefficient, the pothole deceleration effect is calculated as follows:

[0050] a bump =K bump ×V0;

[0051] Among them, K bump It is a deceleration coefficient set according to the degree of potholes, usually based on empirical data, and V0 is the current speed of the car.

[0052] Based on the acceleration / deceleration effects of the above-mentioned road conditions of slope, curves, and potholes, the road surface acceleration can be obtained as a combination of the acceleration affected by the slope and the acceleration affected by the road condition. The specific calculation formula is as follows:

[0053] a road =a gravity -acurve -a bump ;

[0054] Among them, a road Indicates that the road surface affects acceleration.

[0055] In addition, regarding the deceleration effect caused by weather conditions, weather conditions (such as rainy days, snowy days, etc.) affect the deceleration of the car by changing the ground friction. This effect is mainly reflected by the change of the friction coefficient.

[0056] Specifically, the deceleration effect caused by weather conditions mainly depends on the change in friction. The impact of weather on the ground friction coefficient is mainly reflected on wet and slippery roads (rainy days) and icy and snowy roads (snowy days). For example, the deceleration caused by friction can be calculated using the following formula:

[0057] a weather =g×(1-μ weather );

[0058] Where g is the acceleration due to gravity, μ weather It is the coefficient of friction set according to weather conditions.

[0059] For example, the friction coefficient μ on a dry road surface weather ≈0.8;

[0060] Friction coefficient μ on slippery roads in rainy days weather ≈0.5;

[0061] Friction coefficient μ on snowy and icy roads weather ≈0.3.

[0062] Combining the acceleration / deceleration effects of road conditions and weather conditions, the total acceleration / deceleration effect can be obtained:

[0063] a total =a road +a wrather ;

[0064] Based on this comprehensive acceleration / deceleration effect, the speed of the car can be further adjusted to ensure the car's driving safety within a preset time in the future.

[0065] For example, in a practical application scenario, assuming the slope is 5°, the acceleration caused by the slope is calculated as: gravity =9.8×sin(5°)=0.85m / s2;

[0066] Assuming the curve radius R = 50m and the car's current speed is 60km / h (equal to 16.67m / s), calculate the deceleration caused by the curve:

[0067] Assuming the pothole coefficient K bump =0.2, the current speed of the car is 60km / h, calculate the deceleration caused by the pothole: a bump =0.2×16.67=3.33m / s 2 ;

[0068] Assuming it is rainy, the friction coefficient μ weather ≈0.5, calculate the deceleration caused by weather: a weather =9.8×(1-0.5)=4.9m / s 2 ;

[0069] The total acceleration / deceleration effect is then:

[0070] a total =0.85-5.56-3.33-4.9=-12.94m / s 2 .

[0071] At this time, due to the large total deceleration, it indicates that stronger braking intervention or speed adjustment is required to ensure safe driving.

[0072] Hybrid vehicles offer two braking methods: active braking and assisted braking. Active braking can be hydraulic braking, where the driver can control the braking force by pressing the brake pedal, or the controller can control the braking force output. Assisted braking can be either motor braking or engine braking. Motor braking involves converting the vehicle's kinetic energy into electrical energy through the reverse operation of the electric motor during deceleration or braking, which is then stored in the battery. Engine braking uses the internal resistance of the engine to slow the vehicle. Motor braking primarily recovers energy and improves the vehicle's efficiency, while engine braking primarily assists in deceleration but does not recover energy.

[0073] In some embodiments, see Figure 3 In step S102, the target braking mode of the vehicle within a preset time period in the future is determined based on the road conditions and weather conditions ahead of the vehicle, including:

[0074] S301, detecting whether the vehicle is currently actively braking;

[0075] S302, if there is no active braking, determining that the target braking mode of the vehicle within a preset future time period is auxiliary braking;

[0076] S303, if active braking occurs, detecting whether the weather is target weather;

[0077] S304, if the weather is the target weather, determining the target braking mode of the vehicle within a preset time period in the future as active braking and auxiliary braking;

[0078] S305, if the weather is not the target weather, detecting whether the road ahead of the vehicle is the target road based on the road condition;

[0079] S306, if the road surface is the target road surface, determining the target braking mode of the vehicle within a preset time period in the future as active braking and auxiliary braking;

[0080] S307: If the road surface is not the target road surface, determine that the target braking mode of the vehicle within a preset time period in the future is active braking.

[0081] Specifically, active braking can be hydraulic braking, while auxiliary braking includes motor braking and engine braking. In one application scenario, the presence of hydraulic braking is first detected. If not, this means the driver has not applied the brake pedal. Therefore, to ensure safe downhill travel, auxiliary braking is set as the target braking method for a predetermined period of time in the future to provide braking force and ensure safe downhill travel. Auxiliary braking can be motor braking, engine braking, or both. If hydraulic braking is present, the driver has already applied the brakes. The target braking method is then further determined based on road conditions and weather. The target weather can be rain or snow, as rain and snow significantly change the road friction coefficient. Therefore, both active braking and auxiliary braking are used as target braking methods in rainy and snowy weather. Auxiliary braking can be motor braking alone, or a combination of motor and engine braking, to provide sufficient braking force and avoid driving safety impacted by insufficient braking. If the weather is not the target weather, it is further detected whether the road the car is traveling on is the target road surface. The target road surface here is preferably a curved road section and a bumpy road section. If the road surface is a curved road section or a bumpy road section, active braking and auxiliary braking are also used as target braking methods at the same time. At this time, auxiliary braking can be engine braking alone, or the motor and engine jointly assist braking to provide sufficient braking force for the car; on the contrary, if the road surface is not a curved road section or a bumpy road section, it means that the road surface condition and weather condition of the road the car is traveling on are relatively safe, and the driver has already taken active braking, so only active braking is used as the target braking method.

[0082] It can be seen that this embodiment determines the target braking method for providing braking force to the vehicle within a preset time period in the future based on road conditions and weather, thereby avoiding the situation where a single braking method may not be able to provide sufficient braking force under special circumstances and cause an accident. This reasonable allocation of the target braking method for the vehicle within a preset time period in the future can provide favorable guarantees for subsequent adjustments to the braking force.

[0083] In some embodiments, in the above step S103, the braking force of the target braking method is determined based on the difference between the predicted vehicle speed and the safe vehicle speed, including: calculating the speed difference between the predicted vehicle speed and the safe vehicle speed; determining the required acceleration or deceleration based on the speed difference and the future preset time; and adjusting the braking force of the target braking method based on the required acceleration or deceleration.

[0084] Specifically, the difference between the predicted speed and the safe speed can be positive or negative, indicating that the vehicle may need to slow down or accelerate. Specifically, when the predicted speed exceeds the safe speed, the vehicle needs to be decelerated. The target braking force can be increased to decelerate the vehicle. When the predicted speed falls below the safe speed, the vehicle needs to be accelerated. The target braking force can be reduced to accelerate the vehicle.

[0085] Taking auxiliary braking as an example, assuming the target braking mode includes motor braking and hydraulic braking, and the parameters are known:

[0086] Predicted vehicle speed v pred =80km / h (about 22.22m / s), or v pred =40 km / h (about 11.11 m / s);

[0087] Safe speed v safe =60 km / h (about 16.67 m / s);

[0088] Car mass m = 1500 kg;

[0089] Downhill slope θ = 5°;

[0090] Motor braking maximum deceleration a motor =-2m / s 2 ;

[0091] Maximum deceleration of hydraulic brake a hydraulic =-5m / s 2 ;

[0092] Maximum motor acceleration capability a motor,accel =1m / s 2 ;

[0093] The future preset time length T=5s.

[0094] Example 1: For a scenario where the predicted vehicle speed is greater than the safe speed.

[0095] Assume that the predicted vehicle speed v pred =80km / h (about 22.22m / s), safe speed v safe =60km / h. pred >v safe, so deceleration is required, and the total deceleration is calculated as:

[0096]

[0097] That is, the total deceleration required is 1.11 m / s 2 .

[0098] Next, the braking force is distributed: the maximum deceleration provided by the motor is a motor =-2m / s 2 , enough to meet 1.11m / s 2 Therefore, the electric motor brake can be controlled to take on 100% of the braking task, without the need for hydraulic brakes. In this case, relying entirely on the electric motor brake can enable the car to reach a safe speed within the next 5 seconds.

[0099] Example 2: For a scenario where the predicted vehicle speed is lower than the safe speed.

[0100] Assume that the predicted vehicle speed v pred =40km / h (about 11.11m / s), safe speed v safe =60km / h. pred <v safe , so acceleration is required, and the required acceleration is:

[0101]

[0102] Since negative acceleration indicates that acceleration is required, the total acceleration requirement is 1.11 m / s 2 .

[0103] Next, the acceleration capacity is assigned: the maximum acceleration provided by the motor is a motor,accel =1m / s 2 , however, the required acceleration is 1.11m / s 2 , which exceeds the acceleration capability of the motor, so the motor can only provide 1m / s 2 Because the electric motor's acceleration is insufficient, the remaining acceleration can be supplemented by controlling the hydraulic brake release. Therefore, in this scenario, the electric motor can provide approximately 90% of the acceleration capability, with the remainder being achieved through other power sources or by reducing vehicle drag.

[0104] This embodiment reasonably allocates motor braking, hydraulic braking or acceleration means according to the current situation of the car, ensuring that the car reaches a safe speed within a preset time, thereby improving the safety of the car driving downhill.

[0105] In some embodiments, the braking force of the target braking mode is adjusted according to the required acceleration, including: when acceleration is required, detecting the state of active braking; if the active braking is in a valid state, controlling the active braking to reduce the braking force according to the required acceleration; if the active braking is in an invalid state, detecting the state of auxiliary braking; if the auxiliary braking is in a valid state, controlling the auxiliary braking to reduce the braking force according to the required acceleration; if the auxiliary braking is in an invalid state, increasing the power output of the vehicle to compensate for the required acceleration.

[0106] In this embodiment, active braking can be hydraulic braking, and auxiliary braking can be motor braking. When active braking is active, meaning the driver has applied the brake pedal, the hydraulic brake can be controlled to reduce braking force, thereby controlling the active brake to output a braking force that matches the desired acceleration, thereby reducing deceleration and accelerating the vehicle. When active braking is inactive, meaning the hydraulic brake is not outputting braking force to brake the vehicle, it is necessary to detect whether the auxiliary brake is active, that is, whether the auxiliary brake is outputting braking force to brake the vehicle. If the auxiliary brake is active, the motor brake can be controlled to reduce braking force, thereby controlling the auxiliary brake to output a braking force that matches the desired acceleration, thereby reducing resistance to the vehicle and accelerating the vehicle. However, if the auxiliary brake is inactive, meaning the vehicle is not braking at all, the only way to achieve acceleration is to control the vehicle's power output to compensate for the desired acceleration.

[0107] From this we can see that as long as one of the active braking and auxiliary braking has output braking force to brake the car, when acceleration is required, controlling the corresponding braking method to reduce the braking force can reduce the resistance to the car and enable the car to accelerate.

[0108] In addition, if both active braking and auxiliary braking output braking force at the same time, the braking force output by the auxiliary braking can be adjusted according to the braking force of the active braking, or the braking force of the active braking can be actively reduced.

[0109] For example, in one application example, a car is traveling downhill and the predicted speed is less than the safe speed. The driver lightly applies the brake pedal for active braking. The system then needs to reduce braking force to maintain speed. Assume the active braking is hydraulic, and the auxiliary braking is motor braking. First, the active braking force is detected. When the driver lightly applies the brake pedal (hydraulic braking), the system determines the deceleration requirement. Since the predicted speed is lower than the safe speed, the system identifies excessive deceleration and requires reduced braking force. The auxiliary braking force is then adjusted, reducing the deceleration by reducing the motor braking force to an appropriate level. Active braking is then fed back, alerting the driver that active braking may be excessive and allowing them to reduce braking force appropriately. Alternatively, the system can proactively reduce hydraulic braking force, further reducing the deceleration effect while ensuring safety. Finally, the deceleration transition is smooth. Through the combined effects of motor braking and hydraulic braking, the deceleration effect is reduced, and the vehicle speed gradually approaches the safe speed. In this example, the motor braking automatically adjusts the braking force to ensure that deceleration is not excessive and that a safe speed is maintained.

[0110] For example, in another application example, a car is traveling downhill for a long distance and its predicted speed is below the safe speed. If the driver applies a strong brake pedal, the system needs to reduce braking force to prevent the vehicle from underrunning. Assume that the auxiliary braking is engine braking and the active braking is hydraulic braking. First, the system detects the active braking force and detects that the driver has applied a large amount of active braking force (i.e., deeply depressed brake pedal). Next, the system analyzes the current state and determines that the vehicle is decelerating excessively because the current speed is below the safe speed. The auxiliary braking force is then adjusted. Engine braking typically generates braking force by downshifting the gear or reducing engine speed. In this case, the engine braking force can be reduced by shifting up the gear or reducing the engine compression braking effect, thereby reducing the total braking force and avoiding excessive deceleration. Active braking can then be adjusted, either automatically reducing the hydraulic braking force through control logic or by prompting the driver to reduce braking force. Finally, the system monitors the acceleration effect. As the braking force decreases, the vehicle's deceleration weakens, and the vehicle speed gradually increases to a safe range, ensuring that driving instability caused by excessive deceleration is avoided. It can be seen that in this example, engine braking reduces braking force by adjusting the gear or engine compression braking, actively cooperating with the driver's operation to ensure that the vehicle speed rises steadily to a safe value.

[0111] In some embodiments, the braking force of the target braking mode is adjusted according to the required deceleration, including: when deceleration is required, detecting the state of active braking; if the active braking is in a valid state, controlling the active braking to output a braking force that matches the required deceleration; if the active braking is in an invalid state, detecting the state of auxiliary braking; if the auxiliary braking is in a valid state, controlling the auxiliary braking to output a braking force that matches the required deceleration; if the auxiliary braking is in an invalid state, controlling the active braking to output a braking force greater than the required deceleration.

[0112] When the predicted vehicle speed exceeds the safe speed, the vehicle needs to be decelerated. In this case, deceleration is achieved by adjusting active braking (such as hydraulic braking when the driver presses the brake pedal) and auxiliary braking (such as motor braking and engine braking).

[0113] For example, if the target braking mode includes active braking and auxiliary braking, and if the active braking can be hydraulic braking and the auxiliary braking can be motor braking, the following is a complete deceleration control process:

[0114] Step 1: Initially detect the predicted vehicle speed and safe speed to determine whether deceleration is necessary.

[0115] Specifically, the deceleration requirement is determined based on the predicted vehicle speed and the safe vehicle speed. If the predicted vehicle speed is greater than the safe vehicle speed, it is determined that there is a deceleration requirement.

[0116] Step 2: Check the active braking status. If it is not activated, the system actively applies hydraulic brakes.

[0117] Specifically, it reads whether the driver is stepping on the brake pedal to determine whether active braking is activated; if the brake pedal is not stepped on, the hydraulic brake can be actively applied through the driving assistance function to start active braking to reduce the vehicle speed; if the brake pedal is stepped on, go to step three.

[0118] Step three: determine the active braking force and gradually increase the active braking force until it reaches the maximum.

[0119] Specifically, check the braking force of the hydraulic brake and determine whether it has reached the maximum value: if the hydraulic braking force has not reached the maximum value, gradually increase the braking force until it reaches the maximum allowable value; if the hydraulic braking force has reached the maximum value, go to step 4.

[0120] Step 4: Adjust the auxiliary braking force and gradually increase the output of motor braking or engine braking.

[0121] Specifically, the braking force of the motor and engine brakes is first adjusted. If the motor brake has not reached maximum braking force, the control gradually increases the motor braking force. If the engine brake has not reached maximum braking force, the engine speed or gear is gradually adjusted to increase the engine braking force. Next, the braking effect is determined. If the vehicle speed decreases and approaches or reaches the safe speed through the adjustment of active braking and auxiliary braking, the control process ends. If the vehicle speed still does not meet the requirements, the process proceeds to step 5.

[0122] Step 5: Check the braking limit state to confirm whether all braking systems have reached the maximum braking force.

[0123] Specifically, it is determined whether all braking modes have reached the maximum braking force: after both active braking and auxiliary braking have reached the maximum braking force, the system confirms the braking limit state.

[0124] Step six: Take additional deceleration measures.

[0125] Specifically, if active braking and auxiliary braking still cannot meet the deceleration requirements after reaching maximum braking force, further measures may be required. For example, in extreme cases, additional deceleration may be required through other braking systems (such as emergency brakes or mechanical deceleration devices).

[0126] Step seven: Feedback reminds the driver and issues an alarm when braking cannot meet the demand.

[0127] Specifically, when it is detected that both active and auxiliary braking have reached their maximum values ​​and the vehicle speed still does not reach the safety standard, the driver is prompted to manually intervene or take emergency braking measures.

[0128] In order to better understand the steps of this embodiment, two application examples are used for illustration.

[0129] In an application example, assuming that the car is driving downhill and the road conditions are good, the initial detection: predict the vehicle speed v pred =80km / h, safe speed v safe =60km / h; the driver does not brake, the system automatically activates the hydraulic brake, gradually increasing the braking force; the hydraulic braking force reaches the maximum, but the vehicle speed only drops to 75km / h; the system activates the motor brake, increasing the motor braking force, and the vehicle speed drops to 65km / h; the engine brake is not fully utilized, the system automatically increases the engine braking force, and the vehicle speed eventually drops to 60km / h; the control ends, and all braking modes combined meet the deceleration requirements.

[0130] In another application example, suppose a car is driving downhill on a slippery road and the battery is low. Initial detection: predict the vehicle speed v pred =100km / h, safe speed vsafe =70km / h; the driver stepped on the brakes, and the system gradually increased the hydraulic braking force, but the hydraulic braking force was already close to the maximum, and the vehicle speed only dropped to 90km / h; the low battery level limited the motor braking, and the system could only apply part of the motor braking force, so the engine brake intervened and the vehicle speed dropped to 80km / h, but it was still speeding; the system detected the limit state and all braking forces had reached the maximum, prompting the driver to manually intervene; the driver applied emergency braking and decelerated by mechanical means, and the speed eventually dropped to 70km / h.

[0131] It can be seen that this embodiment takes into account the dynamic adjustment of active braking and auxiliary braking during all deceleration processes, and provides countermeasures for various extreme situations to ensure effective control of vehicle speed on downhill or complex road conditions.

[0132] In some embodiments, after controlling the active braking output to match the braking force required for deceleration, it also includes: detecting whether auxiliary braking is involved in braking; if so, increasing the braking force of the auxiliary braking, and synchronously controlling the active braking to reduce the braking force by the same amount.

[0133] This embodiment is applicable to situations where the target braking mode is active braking and auxiliary braking. When deceleration is required, the active braking is first controlled to increase the braking force to decelerate. After deceleration to a safe speed, the braking force of the auxiliary braking is controlled to increase, and at the same time, the braking force of the active braking is controlled to decrease synchronously, so that the auxiliary braking bears the main braking force, thereby reducing braking loss and improving energy recovery efficiency. In particular, when the auxiliary braking is motor braking, kinetic energy can be recovered to replenish the battery of the vehicle.

[0134] All of the above optional technical solutions can be combined in any way to form optional embodiments of the present application, and will not be described in detail here.

[0135] The following are device embodiments of the present application, which can be used to implement the method embodiments of the present application. For details not disclosed in the device embodiments of the present application, please refer to the method embodiments of the present application.

[0136] See also Figure 4 In a second embodiment of the present application, a hybrid vehicle braking control device is provided, comprising:

[0137] The vehicle speed calculation module 401 is configured to calculate the predicted vehicle speed and the safe vehicle speed of the vehicle within a preset time period in the future when the vehicle is traveling downhill;

[0138] The braking strategy module 402 is configured to determine a target braking method for the vehicle within a preset time period in the future based on the road conditions and weather in front of the vehicle;

[0139] The braking control module 403 is configured to determine the braking force of the target braking method according to the difference between the predicted vehicle speed and the safe vehicle speed, so as to brake the vehicle based on the target braking method and braking force.

[0140] This embodiment estimates the safe speed of the car in the future and adjusts the braking force of the corresponding target braking method in combination with road conditions and weather, so that the car's speed is close to the safe speed, thereby improving the safety of the car when driving downhill.

[0141] In some embodiments, the braking control module 403 is configured to calculate the speed difference between the predicted vehicle speed and the safe vehicle speed; determine the required acceleration or deceleration based on the speed difference and the future preset time; and adjust the braking force of the target braking method based on the required acceleration or deceleration.

[0142] In some embodiments, the above-mentioned braking control module 403 is configured to detect the state of active braking when acceleration is required; if the active braking is in a valid state, the active braking is controlled to reduce the braking force according to the required acceleration; if the active braking is in an invalid state, the state of auxiliary braking is detected; if the auxiliary braking is in a valid state, the auxiliary braking is controlled to reduce the braking force according to the required acceleration; if the auxiliary braking is in an invalid state, the vehicle power output is increased to compensate for the required acceleration.

[0143] In some embodiments, the above-mentioned braking control module 403 is configured to detect the state of active braking when deceleration is required; if the active braking is in a valid state, the active braking is controlled to output a braking force that matches the required deceleration; if the active braking is in an invalid state, the state of auxiliary braking is detected; if the auxiliary braking is in a valid state, the auxiliary braking is controlled to output a braking force that matches the required deceleration; if the auxiliary braking is in an invalid state, the active braking is controlled to output a braking force greater than the required deceleration.

[0144] In some embodiments, the braking control module 403 is configured to detect whether auxiliary braking is involved in braking after controlling the active braking output to match the required deceleration; if so, the braking force of the auxiliary braking is increased, and the active braking is synchronously controlled to reduce the braking force by the same amount.

[0145] In some embodiments, the braking strategy module 402 is configured to detect whether the vehicle currently has active braking; if active braking exists, detect whether the weather is target weather; if it is target weather, determine that the target braking mode of the vehicle within a preset time period in the future is active braking and auxiliary braking; if it is not target weather, detect whether the road ahead of the vehicle is a target road surface based on the road surface conditions; if it is a target road surface, determine that the target braking mode of the vehicle within a preset time period in the future is active braking and auxiliary braking; if it is not a target road surface, determine that the target braking mode of the vehicle within a preset time period in the future is active braking; if there is no active braking, determine that the target braking mode of the vehicle within a preset time period in the future is auxiliary braking.

[0146] In some embodiments, the vehicle speed calculation module 401 is configured to obtain the slope data and vehicle driving data of the downhill slope on which the vehicle is traveling; determine the acceleration affected by the slope based on the slope data; determine the acceleration affected by the road conditions based on the road conditions and the slope data on which the vehicle is traveling downhill; determine the acceleration affected by the weather based on the acceleration affected by the weather and the slope; determine the safe speed of the vehicle within a preset time period in the future based on the acceleration affected by the slope, the acceleration affected by the road conditions, the acceleration affected by the weather and the vehicle driving data.

[0147] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0148] See also Figure 5 In a third embodiment of the present application, a vehicle 5 is provided, comprising an active braking system 51, an auxiliary braking system 52, and a controller 53. The active braking system 51 and the auxiliary braking system 52 are respectively connected to the controller 53. In this embodiment, the vehicle 5 is preferably a hybrid vehicle. A hybrid vehicle is a vehicle that uses two or more energy sources to generate kinetic energy, and the drive system can have one or more drive systems. In a hybrid vehicle, the active braking system 51 includes a hydraulic braking system. In practice, the driver can control the braking force output by the hydraulic braking system by adjusting the degree of opening and closing of the brake pedal, or the controller 53 can also control the braking force output by the hydraulic braking system. In addition, the auxiliary braking system 52 includes but is not limited to motor braking and engine braking. Motor braking provides braking force to the vehicle by reverse operation of the electric motor while recovering some energy. Engine braking achieves deceleration by reducing engine speed, especially when driving on a slope or on a long descent, which helps reduce the burden on the hydraulic brake.

[0149] Understandably, in reality, the structure of the car is more Figure 5 More complex. For example, in one application scenario, see Figure 6When a car is driving downhill, the intelligent transportation system predicts that the vehicle has entered a downhill section through the global positioning system and geographic information system. The vehicle slope sensor identifies the road conditions and confirms them, and starts auxiliary braking. The middle layer calculates the auxiliary torque to predict the predicted speed and safe speed of the car for a preset time in the future, and controls the motor, engine and hydraulics to adjust the braking force. While recovering energy, it monitors the road conditions through sensors, and can use cameras, wheel speed sensors and laser remote sensing road surface state sensors to identify whether there are potholes and curves ahead, or whether the current road weather conditions are rainy or snowy. With safety and positivity as the goals, the auxiliary braking torque is distributed according to the braking capacity of each braking system (including motor braking, engine braking and hydraulic braking). The bottom layer dynamically coordinates and controls each system for the working conditions of combined braking of different braking systems, so as to give full play to the advantages of each braking system and improve the braking performance of the entire vehicle.

[0150] See also Figure 7 In some embodiments, the controller 53 includes a processor 531, a memory 532, and a computer program 533 stored in the memory 532 and executable on the processor 531. When the processor 531 executes the computer program 533, the steps of the aforementioned method embodiments are implemented. Alternatively, when the processor 531 executes the computer program 533, the functions of the modules in the aforementioned device embodiments are implemented.

[0151] The controller may be a vehicle controller or a microcontroller for controlling a braking system, and this embodiment of the present application does not limit this. The controller 53 may include but is not limited to a processor 531 and a memory 532. It will be understood by those skilled in the art that Figure 7 The controller 53 is merely an example and does not limit the controller 53 , and may include more or fewer components than shown in the figure, or different components.

[0152] The processor 531 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0153] The memory 532 can be an internal storage unit of the controller 53, such as a hard disk or memory of the controller 53. The memory 532 can also be an external storage device of the controller 53, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card, etc. equipped on the controller 53. The memory 532 can also include both the internal storage unit of the controller 53 and an external storage device. The memory 532 is used to store computer programs and other programs and data required by the controller.

[0154] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0155] If the integrated module is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium (such as a computer-readable storage medium). Based on this understanding, the present application implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. The computer program may include computer program code, which may be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0156] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A hybrid vehicle braking control method, characterized in that: include: When the car is driving downhill, the predicted speed and safe speed of the car within a preset time period in the future are calculated respectively; determining a target braking mode for the vehicle within a preset time period in the future based on road conditions and weather conditions ahead of the vehicle; determining a braking force of the target braking mode according to a difference between the predicted vehicle speed and the safe vehicle speed, and braking the vehicle based on the target braking mode and the braking force; Calculating the safe speed of a car within a preset time in the future includes: Obtaining downhill slope data and vehicle driving data; determining an acceleration affected by the slope based on the slope data; Determine the acceleration affected by the road conditions based on the downhill road conditions and slope data of the vehicle; Determine the acceleration affected by weather based on the acceleration affected by weather and slope; Determine the safe speed of the vehicle within a preset time period in the future based on the acceleration affected by slope, road conditions, weather, and vehicle driving data; Determining a target braking mode for the vehicle within a preset time period in the future based on the road conditions and weather ahead of the vehicle includes: Detect whether the car is currently actively braking; If the active braking occurs, detecting whether the weather is target weather; If the weather is the target weather, the target braking mode of the vehicle within the preset time period in the future is determined to be active braking and auxiliary braking; If the weather is not the target weather, detecting whether the road ahead of the vehicle is the target road based on the road condition; If the road surface is the target road surface, determining that the target braking mode of the vehicle within a preset time period in the future is active braking and auxiliary braking; If the road surface is not the target road surface, determining that the target braking mode of the vehicle within a preset time period in the future is active braking; If there is no active braking, determining that the target braking mode of the vehicle within a preset time period in the future is auxiliary braking; The step of determining the braking force of the target braking mode according to the difference between the predicted vehicle speed and the safe vehicle speed includes: Calculating a speed difference between the predicted vehicle speed and the safe vehicle speed; determining a required acceleration or deceleration according to the speed difference and the future preset time; The braking force of the target braking mode is adjusted according to the required acceleration or deceleration.

2. The method according to claim 1, characterized in that Adjusting the braking force of the target braking method according to the required acceleration includes: Detect the status of active braking when acceleration is required; If the active braking is in a valid state, controlling the active braking to reduce the braking force according to the required acceleration; If the active brake is in an invalid state, detecting the state of the auxiliary brake; If the auxiliary brake is in a valid state, the auxiliary brake is controlled to reduce the braking force according to the required acceleration; If the auxiliary brake is in an invalid state, the vehicle power output is increased to compensate for the required acceleration.

3. The method according to claim 1, characterized in that Adjusting the braking force of the target braking method according to the required deceleration includes: Detect the status of active braking when deceleration is required; If the active brake is in a valid state, controlling the active brake to output a braking force that matches the required deceleration; If the active brake is in an invalid state, detecting the state of the auxiliary brake; If the auxiliary brake is in a valid state, controlling the auxiliary brake to output a braking force that matches the required deceleration; If the auxiliary brake is in an invalid state, the active brake is controlled to output a braking force greater than the required deceleration.

4. The method according to claim 3, characterized in that After controlling the active braking to output a braking force that matches the required deceleration, the method further includes: Detecting whether the auxiliary brake is involved in braking; If braking is involved, the auxiliary braking force is increased, and the active braking is synchronously controlled to reduce the braking force by the same amount.

5. A hybrid vehicle braking control device, characterized in that: include: The vehicle speed calculation module is configured to calculate the predicted vehicle speed and the safe vehicle speed of the vehicle within a preset time period in the future when the vehicle is traveling downhill; a braking strategy module configured to determine a target braking mode for the vehicle within a preset time period in the future based on road conditions and weather conditions ahead of the vehicle; a braking control module configured to determine a braking force of the target braking mode according to a difference between the predicted vehicle speed and the safe vehicle speed, and brake the vehicle based on the target braking mode and the braking force; The vehicle speed calculation module is specifically configured to: obtain downhill slope data and vehicle driving data of the vehicle; determine the acceleration affected by the slope based on the slope data; determine the acceleration affected by the road condition based on the downhill road condition and the slope data; determine the acceleration affected by the weather based on the acceleration affected by the weather and the slope; and determine the safe speed of the vehicle within a preset time period in the future based on the acceleration affected by the slope, the acceleration affected by the road condition, the acceleration affected by the weather, and the vehicle driving data; The braking strategy module is specifically configured to: detect whether the vehicle is currently in active braking; if active braking is present, detect whether the weather is target weather; if it is target weather, determine that the target braking mode of the vehicle within a preset time period in the future is active braking and auxiliary braking; If the weather is not the target weather, detecting whether the road ahead of the vehicle is the target road based on the road condition; if it is the target road, determining that the target braking mode of the vehicle for a preset time in the future is active braking and auxiliary braking; if it is not the target road, determining that the target braking mode of the vehicle for a preset time in the future is active braking; if there is no active braking, determining that the target braking mode of the vehicle for a preset time in the future is auxiliary braking; The braking control module is specifically configured to: calculate the speed difference between the predicted vehicle speed and the safe vehicle speed; determine the required acceleration or deceleration based on the speed difference and the future preset time; and adjust the braking force of the target braking method based on the required acceleration or deceleration.

6. A car, characterized in that: The method comprises an active braking system, an auxiliary braking system and a controller, wherein the active braking system and the auxiliary braking system are respectively connected to the controller, and the controller comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

7. A readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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