A method for automotive brake energy recovery that takes driving style into account

Abstract

This invention discloses a method for automotive braking energy recovery that considers driving style, comprising: determining the driver's driving style and the corresponding comfortable headway; wherein the driving style includes aggressive, normal, and cautious; when the real-time headway is greater than the safe headway, identifying the driver's current braking intention based on the current accelerator pedal position, accelerator pedal change rate, and the difference between the real-time headway and the comfortable headway; the type of braking intention includes: mild, mild-moderate, moderate, and emergency; if the driver's current braking intention is mild or mild-moderate, a regenerative braking strategy is adopted; if the driver's current braking intention is moderate, a hybrid strategy of regenerative braking and mechanical braking is adopted; if the driver's current braking intention is emergency, a mechanical braking strategy is adopted. This invention can improve the accuracy of driving intention recognition, thereby improving driving comfort and the efficiency of braking energy recovery.

Description

Technical Field

[0001] This invention relates to the field of electric vehicles, and more particularly to a method for regenerating braking energy in a vehicle that takes into account driving style. Background Technology

[0002] Driving range is a crucial performance indicator for electric vehicles (EVs), and regenerative braking is not only an important method for improving EV range but also a vital component of energy management for new energy vehicles. Unlike traditional gasoline-powered vehicles, the braking process of EVs involves both electric motor braking and mechanical braking. Regenerative braking refers to the EV prioritizing the use of the electric motor for braking, converting braking energy into electrical energy and storing it in an energy storage device, while simultaneously providing regenerative braking force. This energy recovery method is significant for the energy conservation and environmental protection of EVs. Through regenerative braking, EVs can maximize the use of energy generated during braking, extending driving range and reducing dependence on external energy sources. This not only helps improve the energy efficiency of EVs but also reduces energy consumption and emissions, having a positive impact on environmental protection.

[0003] The most commonly used method for regenerative braking is to improve the energy recovery rate by adjusting the ratio of electric braking force to mechanical braking force. Its control strategies are generally divided into rule-based braking force distribution control strategies and optimization-based braking force distribution control strategies. Rule-based methods include those that formulate rules based on driver intent and fuzzy rules. These methods offer good real-time performance and are highly practical, but their effectiveness is poor under more complex operating conditions. Optimization-based methods include model predictive control, genetic algorithms, and particle swarm optimization. These methods perform well in terms of distribution effectiveness, but their real-time performance is poor and their computational cost is high.

[0004] People with different driving styles have different driving habits. Rules formulated with uniform standards cannot guarantee the accuracy of driving intention recognition, nor can they guarantee that the car will achieve the best braking stability and braking energy recovery efficiency for different driving styles. Taking the driver's driving style into the braking strategy is one of the challenges of future braking energy recovery. Summary of the Invention

[0005] This invention provides a method for regenerating braking energy in automobiles that takes into account driving style. This method can improve the accuracy of driving intention recognition, thereby improving driving comfort, the efficiency of braking energy recovery, and the driving range of electric vehicles, and improving economy.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A method for regenerative braking of a vehicle that takes into account driving style includes:

[0008] Step 1: Determine the driver's driving style and the corresponding comfort headway; wherein the driving style includes aggressive, normal, and cautious.

[0009] Step 2: When the real-time headway is greater than the safe headway, the driver's current braking intention is identified based on the current accelerator pedal position, accelerator pedal change rate, and the difference between the real-time headway and the comfortable headway. The types of braking intentions include: mild, mild-moderate, moderate, and emergency.

[0010] Step 3: If the driver's current braking intention is mild or moderate, then a regenerative braking strategy is adopted.

[0011] If the driver's current braking intention is moderate, a hybrid strategy of regenerative braking and mechanical braking will be adopted.

[0012] If the driver's current braking intention is an emergency, then a mechanical braking strategy should be adopted;

[0013] The hybrid strategy of regenerative braking and mechanical braking has a cost function that includes two parts: braking energy recovery rate and braking stability. Different weighting coefficients are assigned to different driving styles: for aggressive drivers, the weight of braking stability is higher than that of braking energy recovery rate; for cautious drivers, the weight of braking energy recovery rate is higher than that of braking stability; and for average drivers, the weights of braking energy recovery rate and braking stability are the same.

[0014] Furthermore, by referencing a large amount of historical driving data from various types of drivers, and using clustering algorithms, the driving style of each driver is determined; the types of historical driving data include: headway, average deceleration, average acceleration, average accelerator pedal position, and accelerator pedal change rate.

[0015] Furthermore, we first used principal component analysis to reduce the dimensionality of each historical driving data, and then used the K-Medoids clustering algorithm to classify the drivers corresponding to each historical driving data into three categories: aggressive, normal, and cautious.

[0016] Furthermore, headway refers to the time it takes for this vehicle to travel from its current position to the position of the vehicle in front, expressed as: Different comfort headroom settings are achieved based on the vehicle's speed.

[0017] Furthermore, if it is determined that the current real-time headway is less than the safe headway, or the current real-time vehicle speed exceeds a preset value, or the charge state of the regenerative braking battery exceeds a preset value, or the brake pedal position is not zero, then the driver's braking intention is directly identified as an emergency; otherwise, fuzzy logic rules are established to identify the following types of braking intentions of the driver: mild, mild-moderate, and moderate.

[0018] The fuzzy logic rule takes the current accelerator pedal position, the accelerator pedal change rate, and the difference between the real-time head-to-head distance and the comfortable head-to-head distance as inputs, and outputs three braking intentions: light, light-medium, and medium intensity.

[0019] Furthermore, if the driver's current braking intention is mild, when adopting a regenerative braking strategy, the total torque required by the vehicle will be provided entirely by the regenerative braking force of the front wheels.

[0020] If the driver's current braking intention is light to moderate, when adopting a regenerative braking strategy, the regenerative braking force of the front wheels and the regenerative braking force of the rear wheels will jointly provide the total torque required by the vehicle.

[0021] If the driver's current braking intention is an emergency, when a mechanical braking strategy is adopted, the total torque required by the vehicle is provided by the mechanical braking of the front axle and the mechanical braking of the rear axle.

[0022] Furthermore, the cost function of any braking strategy can be uniformly expressed as the following multi-objective optimization cost function:

[0023]

[0024]

[0025]

[0026] In the formula, These are the weighting coefficients for braking stability and braking energy recovery rate, respectively. The front and rear axle braking torque distribution coefficient, i.e. , This is the total torque required by the vehicle. This refers to the braking torque of the front axle. For the ideal front and rear axle braking torque distribution coefficient, For regenerative braking torque, This indicates the ideal charging torque;

[0027] This is the longitudinal distance from the vehicle's center of gravity to the rear axle. This refers to the front and rear wheelbase. Indicates braking intensity; The height of the vehicle's center of gravity; This represents the battery's maximum charging torque. This represents the maximum charging torque of the entire motor.

[0028] Furthermore, the constraints on arbitrary braking strategies include:

[0029] (1) The total regenerative braking torque shall not exceed the maximum charging torque of the motor, and the torque of a single motor shall not exceed the maximum charging torque of each individual motor.

[0030]

[0031]

[0032]

[0033] In the formula, For regenerative braking torque on the front axle, Regenerative braking torque for the rear axle and These represent the maximum charging torque of the front axle motor and the rear axle motor, respectively.

[0034] (2) The regenerative braking torque shall not exceed the total braking torque, and the regenerative braking torque of the front axle shall not exceed the total regenerative braking torque:

[0035]

[0036]

[0037] In the formula, The ratio of regenerative braking torque is the coefficient. , If a regenerative braking strategy is adopted, then If a hybrid strategy of regenerative braking and mechanical braking is adopted, then If a mechanical braking strategy is adopted, then ; This is the ratio of the regenerative braking torque on the front axle, i.e. , This is the regenerative braking torque for the front axle;

[0038] (3) For light braking intent and light to moderate braking intent, the front and rear axle braking force distribution coefficient shall be determined according to braking regulations. With braking strength The following conditions must be met between them:

[0039] (0≤z≤0.3)

[0040] (0.15≤z≤0.3)

[0041] For moderate-intensity braking, the front and rear axle braking force distribution coefficient should be considered according to braking regulations. With braking strength The following conditions must be met between them.

[0042] (0.15≤z≤0.3)

[0043] (0.2≤z≤0.8)

[0044] Among them, braking strength It is expressed as the ratio of braking deceleration to gravitational acceleration. , These are the longitudinal distances from the center of gravity to the front and rear axles, respectively. Wheelbase ; This refers to the height of the vehicle's center of gravity.

[0045] Compared with existing braking energy recovery methods, the present invention has the following advantages:

[0046] 1. By using the rate of change of releasing the accelerator pedal as one of the inputs to the fuzzy logic control rules, the problem of low energy recovery caused by the low frequency of the driver pressing the brake pedal when driving a car in single-pedal mode is solved.

[0047] 2. By taking driving style factors into account, a comfortable (habitual) headway concept is introduced on the basis of the original fuzzy logic control, which improves the accuracy of recognizing the braking intentions of different drivers, thereby improving driving comfort.

[0048] 3. By matching personalized braking force distribution strategies to three different driving styles and optimizing them accordingly, braking energy can be recovered as much as possible while ensuring braking efficiency, thereby increasing the driving range of electric vehicles. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the driver braking intention recognition method described in the embodiments of this application;

[0050] Figure 2 This is a flowchart of the braking energy recovery method described in the embodiments of this application. Detailed Implementation

[0051] The embodiments of the present invention will be described in detail below. These embodiments are based on the technical solutions of the present invention and provide detailed implementation methods and specific operation processes to further explain the technical solutions of the present invention.

[0052] This embodiment provides a method for automotive braking energy recovery that takes into account driving style, referencing... Figure 1 ,2 Shown, including:

[0053] Step 1: Determine the driver's driving style and the corresponding comfort headway; wherein the driving style includes aggressive, normal, and cautious.

[0054] By referencing a large amount of historical driving data from various types of drivers, including headway, average deceleration, average acceleration, average accelerator pedal position, and accelerator pedal change rate, and using clustering algorithms, the driving styles of drivers are determined.

[0055] First, Principal Component Analysis (PCA) was used to reduce the dimensionality of each historical driving data. Then, the K-Medoids clustering algorithm was used to classify the drivers corresponding to each historical driving data into three driving styles: aggressive, normal, and cautious.

[0056] The headway refers to the time interval between two vehicles when their front ends pass the same position, i.e., the time it takes for one vehicle to travel from its current position to the position of the vehicle in front. Specifically, it can be expressed as:

[0057] ;

[0058] Based on historical driving data of following distance during multiple trips for three driving styles, frequency analysis was used to obtain the comfortable (habitual) headway for each of the three driving styles. The comfortable headway for the aggressive driving style was denoted as... The comfortable headway for a standard driver is recorded as follows: The comfort headway for a cautious driver is recorded as follows: .

[0059] Step 2, identify the driver's current braking intention: When the real-time headway is greater than the safe headway, the driver's current braking intention is identified based on the current accelerator pedal position, accelerator pedal change rate, and the difference between the real-time headway and the comfortable headway. The types of braking intentions include: mild, mild-moderate, moderate, and emergency.

[0060] Emergency braking occurs when a driver encounters an emergency, releases the accelerator pedal, and slams on the brake pedal to immediately reduce the vehicle speed to zero. This requires significant braking force and deceleration. Emergency braking is a special situation, triggered when the accelerator pedal is at zero position and the brake pedal position changes. Therefore, when these conditions are met, the driving intention is considered emergency braking.

[0061] In addition, if the current real-time headway is determined to be less than the safe headway, or the current real-time vehicle speed is determined to exceed a preset value, or the charge state of the regenerative braking battery exceeds a preset value, the driver's braking intention will also be directly identified as an emergency.

[0062] If the following conditions need to be met, then fuzzy logic rules can be established to identify several other braking intentions of the driver.

[0063] (1) The real-time headway is greater than the safe headway.

[0064] When the real-time headway is less than the safe headway, the vehicle is in a dangerous driving situation. At this time, the maximum braking force is required to keep the vehicle in a safe state. Providing pure mechanical braking force is a better choice. According to existing research, when the headway is less than 0.6s, the vehicle is in a dangerous driving state. Therefore, this embodiment sets the minimum safe headway to 0.6s.

[0065] (2) The real-time vehicle speed is greater than 10m / s.

[0066] (3) Real-time SOC of regenerative braking battery <90%. When SOC >90%, the corresponding braking force is still provided according to the required braking intensity. In order to reduce the battery SOH loss, the required braking force is provided by mechanical braking force and no longer regenerative braking force is provided.

[0067] (4) The brake pedal was not engaged.

[0068] The recognition of braking intentions for three different driving styles is performed separately. Taking fuzzy logic control as an example, the accelerator pedal position is... accelerator pedal change rate Real-time headway and comfortable headway (for the aggressive model) The standard type is Conservative type The difference between the values ​​is used as the input to the fuzzy logic controller, and the accelerator pedal change rate is... , For the next step, use the accelerator pedal for an extended period of time. The time step is 1. The output shows the driver's braking intention, categorized as light braking, light-moderate braking, and moderate braking. Different braking intentions correspond to different braking intensity ranges. Taking fuzzy logic as an example, the specific fuzzy logic rules are as follows:

[0069] Accelerator pedal opening {zero (Z), small (S), medium (M), large (L)};

[0070] Accelerator pedal change rate {Negative small (NS), negative medium (NM), negative large (NL), zero (Z)};

[0071] Comfortable following distance {zero (Z), negative small (NS), negative medium (NM), negative large (NL)};

[0072] Driving intentions {slow acceleration (SA), normal acceleration (NA), rapid acceleration (RA), coasting (GL), slow deceleration (SB), normal deceleration (NB), rapid deceleration (RB)}; where slow deceleration (SB), normal deceleration (NB), and rapid deceleration (RB) in driving intentions correspond to light, light-medium, and medium intensity braking intentions.

[0073] This fuzzy rule is primarily used to identify the driver's braking intention. Positive changes in the accelerator pedal reflect the driver's acceleration intention, so only negative changes in the accelerator pedal change rate are recognized. The distance to the comfortable following distance represents the difference between the real-time following distance and the comfortable following distance. Z represents the driver's current comfortable following distance, and NL represents the driver's current following distance being very close to the safe following distance. If the driver's current following distance is greater than the comfortable following distance, without pressing the brake pedal, the driver's driving intention is more inclined to accelerate to the comfortable following distance; therefore, this situation is not considered in the fuzzy rule. The specific fuzzy rules in this embodiment are shown in Table 1:

[0074]

[0075] The different braking intentions explained in this article are as follows:

[0076] Light braking indicates that the driver intends to maintain or gradually reduce the vehicle speed. In this case, only a small braking force and deceleration are required, and the corresponding braking intensity z range is 0. <z<0.1。

[0077] Light to moderate braking indicates that the driver intends to reduce the current vehicle speed. This requires a moderate amount of braking force and intensity, with the corresponding braking intensity z ranging from 0.1. <z<0.2。

[0078] Medium-intensity braking represents the driver's intention to quickly reduce the current vehicle speed. This requires a moderate to high level of braking force and intensity, corresponding to a braking intensity z-range of 0.2. <z<0.7。

[0079] Emergency braking occurs when a driver encounters an emergency, releases the accelerator pedal and slams on the brake pedal to immediately reduce the vehicle speed to 0. This requires a large braking force and deceleration. Emergency braking is a special situation, and its triggering conditions are that the accelerator pedal is at 0 and the brake pedal position changes.

[0080] Step 3: Take the corresponding braking strategy based on the driver's current braking intention.

[0081] (1) Light braking: If the driver’s current braking intention is light braking, then a regenerative braking strategy is adopted.

[0082] When the driver's intention to brake is detected as slight, the required braking force is small and can be provided by the regenerative braking force of the front wheels. However, considering maximizing energy recovery, all the required braking force is provided by the regenerative braking force of the front wheels. , , ,in For the required total torque, This is the total regenerative braking torque. Regenerative braking force for the front axle. Total mechanical braking torque, braking force distribution coefficient .

[0083] (2) Light to moderate braking: If the driver’s current braking intention is light to moderate braking, then a regenerative braking strategy is adopted.

[0084] When the driver's intention to brake moderately is detected, and the front wheel regenerative braking force is insufficient to provide the required braking force, the rear wheel regenerative braking force intervenes to maximize energy recovery while ensuring safety. ,in Regenerative braking torque for the rear axle , This is the front axle regenerative braking ratio coefficient. , The coefficient representing the proportion of regenerative braking force and the coefficient representing the distribution of braking force. .

[0085] (3) Medium-intensity braking: If the driver’s current braking intention is medium-intensity braking, a mixed strategy of regenerative braking and mechanical braking shall be adopted.

[0086] When the driver's intention to brake at a moderate intensity is detected, the regenerative braking force of the front and rear wheels is insufficient to meet the required braking force. Therefore, prioritizing energy recovery while ensuring safety, mechanical braking force is activated. , , ,in This is the mechanical braking torque of the front axle. Rear axle mechanical braking torque, mechanical braking force distribution coefficient Braking force distribution coefficient .

[0087] (4) Emergency braking: If the driver’s current braking intention is emergency braking, then mechanical braking strategy shall be adopted.

[0088] When the driver's intention to brake urgently is detected, a large braking force is required, and the braking situation is urgent. Because the regenerative braking force reacts relatively slowly, the required regenerative braking force is entirely provided by the mechanical braking force. , , , , Braking force distribution coefficient .

[0089] The constraints and cost functions of the braking strategy optimization models in the embodiments of the present invention.

[0090] 1. Restrictions

[0091] The limiting conditions of the braking strategy in the embodiments of the present invention include:

[0092] (1) The total regenerative braking torque shall not exceed the maximum charging torque of the motor, and the torque of a single motor shall not exceed the maximum charging torque of each individual motor.

[0093]

[0094]

[0095]

[0096] In the formula, For regenerative braking torque on the front axle, Regenerative braking torque for the rear axle and These represent the maximum charging torque of the front axle motor and the rear axle motor, respectively.

[0097] (2) The regenerative braking torque shall not exceed the total braking torque, and the regenerative braking torque of the front axle shall not exceed the total regenerative braking torque:

[0098]

[0099]

[0100] In the formula, The ratio of regenerative braking torque is the coefficient. , If a regenerative braking strategy is adopted, then If a hybrid strategy of regenerative braking and mechanical braking is adopted, then If a mechanical braking strategy is adopted, then ; represents the proportion of regenerative braking torque on the front axle, i.e. , This is the regenerative braking torque for the front axle;

[0101] (3) For light braking intent and light to moderate braking intent, the front and rear axle braking force distribution coefficient shall be determined according to braking regulations. With braking strength The following conditions must be met between them:

[0102] (0≤z≤0.3)

[0103] (0.15≤z≤0.3)

[0104] For moderate-intensity braking, the front and rear axle braking force distribution coefficient should be considered according to braking regulations. With braking strength The following conditions must be met between them.

[0105] (0.15≤z≤0.3)

[0106] (0.2≤z≤0.8)

[0107] The braking intensity is represented by the ratio of braking deceleration to gravitational acceleration. , These are the longitudinal distances from the center of gravity to the front and rear axles, respectively. Wheelbase ; This refers to the height of the vehicle's center of gravity.

[0108] 2. Cost function

[0109] Because braking force is entirely provided by regenerative braking force from the front axle during light braking, and entirely by mechanical braking force during heavy braking, the optimization model in this embodiment is only applicable to light-to-moderate and moderate-intensity braking, and does not include optimization for light and heavy braking. This optimization mathematical model proposes two optimization objectives: optimal braking stability and maximum regenerative braking efficiency.

[0110] (1) Optimal braking stability

[0111] During braking, it is unacceptable for the rear wheels to lock up before the front wheels, as this will cause the vehicle to lose stability. Conversely, simultaneous locking of the front and rear wheels provides optimal braking stability. In this case, the distribution of braking force follows the ideal braking force curve, also known as the I-curve, where:

[0112]

[0113] To optimize braking force distribution and achieve the best braking stability, the following cost function is established:

[0114]

[0115] (2) Maximum regenerative braking efficiency

[0116] To achieve maximum regenerative braking efficiency, an ideal charging torque is required. The ideal charging torque is determined by the minimum of the battery's maximum charging torque and the motor's maximum charging torque, i.e.:

[0117]

[0118] In the formula This represents the battery's maximum charging torque. This represents the maximum charging torque of the motor. In this invention, during regenerative braking, the energy is fed back to the battery for charging. The battery provides electrical energy to the motor, which, as an energy conversion device, converts the electrical energy from the battery into mechanical energy.

[0119] To optimize the ideal charging torque for maximum regenerative braking efficiency, the following cost function is established:

[0120]

[0121] For regenerative braking, optimizing both objectives simultaneously requires multi-objective optimization. Multi-objective optimization refers to finding the optimal solution for an optimization problem with multiple conflicting objective functions, such that these objective functions reach their optimal or near-optimal states. In multi-objective optimization, there is no longer a single optimization objective, but rather multiple independent and potentially conflicting objectives. The goal of multi-objective optimization is to ensure that these solutions reach optimal or near-optimal states across multiple objective functions, rather than simply pursuing the optimal solution for a single objective function. Commonly used multi-objective algorithms include genetic algorithms, particle swarm optimization, and gray wolf algorithms; any one of these algorithms can be chosen.

[0122] Therefore, the multi-objective optimization cost function established in this embodiment of the invention is as follows:

[0123]

[0124] In the formula and These are the weighting coefficients for braking stability and energy recovery rate, respectively. By adjusting the weighting coefficients according to driving style, braking stability and energy recovery can be better balanced.

[0125] The weighting coefficients adjusted based on driving style can be determined from existing driving data. For aggressive drivers, who typically drive at higher speeds and experience relatively higher deceleration during braking, a more optimized implementation can assign a higher weight to braking stability for safety reasons. For cautious drivers, who travel at relatively low speeds and experience relatively low braking deceleration, energy recovery rate can be given a higher weight. To maximize the effect of energy recovery.

[0126] The above embodiments are preferred embodiments of this application. Those skilled in the art can make various changes or improvements based on them. Without departing from the overall concept of this application, these changes or improvements should fall within the scope of protection claimed in this application.

Claims

1. A method for regenerating braking energy in a vehicle that takes into account driving style, characterized in that, include: Step 1: Determine the driver's driving style and the corresponding comfort headway; wherein the driving style includes aggressive, normal, and cautious. Step 2: When the real-time headway is greater than the safe headway, the driver's current braking intention is identified based on the current accelerator pedal position, accelerator pedal change rate, and the difference between the real-time headway and the comfortable headway. The types of braking intentions include: mild, mild-moderate, moderate, and emergency. Step 3: If the driver's current braking intention is mild or moderate, then a regenerative braking strategy is adopted. If the driver's current braking intention is moderate, a hybrid strategy of regenerative braking and mechanical braking will be adopted. If the driver's current braking intention is an emergency, then a mechanical braking strategy should be adopted; The hybrid strategy of regenerative braking and mechanical braking has a cost function that includes two parts: braking energy recovery rate and braking stability. Different weighting coefficients are assigned to different driving styles: for aggressive drivers, the weight of braking stability is higher than that of braking energy recovery rate; for cautious drivers, the weight of braking energy recovery rate is higher than that of braking stability; and for average drivers, the weights of braking energy recovery rate and braking stability are the same. The cost function of any braking strategy can be uniformly expressed as the following multi-objective optimization cost function: T opt =min{max(T bat_cha ),max(T motor_cha )} In the formula, ω1 and ω2 are the weighting coefficients for braking stability and braking energy recovery rate, respectively; β is the distribution coefficient of braking torque between the front and rear axles, i.e. T s T is the total torque required by the vehicle. f β is the front axle braking torque. opt T is the ideal front and rear axle braking torque distribution coefficient. E For regenerative braking torque, T opt This indicates the ideal charging torque; b is the longitudinal distance from the vehicle's center of gravity to the rear axle, L is the front and rear wheelbase, and z represents the braking intensity; H g T is the height of the vehicle's center of gravity. bat_cha T represents the battery's maximum charging torque. motor_cha This represents the maximum charging torque of the entire motor.

2. The method for automobile braking energy recovery considering driving style according to claim 1, characterized in that, By referencing a large amount of historical driving data from various types of drivers, and using clustering algorithms, the driving styles of drivers can be determined. The types of historical driving data include: headway, average deceleration, average acceleration, average accelerator pedal position, and accelerator pedal change rate.

3. The method for automobile braking energy recovery considering driving style according to claim 2, characterized in that, First, principal component analysis was used to reduce the dimensionality of each historical driving data. Then, the K-Medoids clustering algorithm was used to classify the drivers corresponding to each historical driving data into three categories: aggressive, average, and cautious.

4. The method for automobile braking energy recovery considering driving style according to claim 1, characterized in that, Headway refers to the time it takes for your vehicle to travel from its current position to the position of the vehicle in front of it. It is expressed as: Headway = Distance between the two vehicles / Vehicle speed. Different comfort headway settings are based on different vehicle speeds to obtain different comfort headway settings.

5. The method for automobile braking energy recovery considering driving style according to claim 1, characterized in that, If it is determined that the current real-time headway is less than the safe headway, or the current real-time vehicle speed exceeds the preset value, or the charge state of the regenerative braking battery exceeds the preset value, or the brake pedal position is not 0, then the driver's braking intention will be directly identified as an emergency. Otherwise, by establishing fuzzy logic rules, the following braking intentions of the driver can be identified: mild, mild-moderate, and moderate. The fuzzy logic rule takes the current accelerator pedal position, the accelerator pedal change rate, and the difference between the real-time head-to-head distance and the comfortable head-to-head distance as inputs, and outputs three braking intentions: light, light-medium, and medium intensity.

6. The method for automobile braking energy recovery considering driving style according to claim 1, characterized in that, If the driver's current braking intention is mild, when adopting a regenerative braking strategy, the total torque required by the vehicle will be provided entirely by the regenerative braking force of the front wheels; If the driver's current braking intention is light to moderate, when adopting a regenerative braking strategy, the regenerative braking force of the front wheels and the regenerative braking force of the rear wheels will jointly provide the total torque required by the vehicle. If the driver's current braking intention is an emergency, when a mechanical braking strategy is adopted, the total torque required by the vehicle is provided by the mechanical braking of the front axle and the mechanical braking of the rear axle.

7. The method for automobile braking energy recovery considering driving style according to claim 1, characterized in that, The limitations of arbitrary braking strategies include: (1) Regenerative braking torque T E The maximum charging torque of the motor must not be exceeded, and the maximum charging torque of any single motor must not be exceeded. T E ≤T motor_cha T Ef ≤T motor_cha1 T Er ≤T motor_cha2 In the formula, T Ef For the regenerative braking torque of the front axle, T Er For regenerative braking torque on the rear axle, T motor_cha1 and T motor_cha2 These represent the maximum charging torque of the front axle motor and the rear axle motor, respectively. (2) Regenerative braking torque T E It must not exceed the total torque required by the vehicle, T. S The regenerative braking torque of the front axle must not exceed the regenerative braking torque T. E : 0≤α≤1 0≤γ≤1 In the formula, α is the proportion coefficient of regenerative braking torque, i.e. T S =T E +T M If a regenerative braking strategy is adopted, then α = 1; if a mixed strategy of regenerative braking and mechanical braking is adopted, then 0 < α < 1; if a mechanical braking strategy is adopted, then α = 0; γ is the proportion coefficient of the regenerative braking torque on the front axle, i.e. T M This refers to the mechanical braking torque; (3) For light braking intent and light to moderate braking intent, according to braking regulations, the front and rear axle braking force distribution coefficient β and braking intensity z must meet the following conditions: For medium-intensity braking, according to braking regulations, the front-to-rear axle braking torque distribution coefficient β and the braking intensity z must satisfy the following conditions. Wherein, braking intensity z is represented by the ratio of braking deceleration to gravitational acceleration, a and b are the longitudinal distances from the center of gravity to the front axle and rear axle, respectively; L is the wheelbase, L = a + b.

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