Electric drive semitrailer grading AEB control decision-making method considering road surface factors

Abstract

The invention relates to an electric drive semitrailer grading AEB control decision-making method considering road surface factors, and the method comprises the following steps: S1, enabling a vehicle to obtain front vehicle information and road surface information through a sensor, a high-precision map and other ways, calculating a correction adhesion coefficient through combining with the state of the vehicle, and determining the maximum gradient limit; s2, outputting a maximum braking deceleration correction factor through fuzzy control by taking the correction adhesion coefficient and the gradient as input; s3, according to the advantages and disadvantages of the road surface working conditions and the maximum braking deceleration correction factor, the maximum braking deceleration is calculated according to the working conditions; s4, calculating a safe braking distance and collision time according to the current state of the vehicle and the speed and distance of the front vehicle; and S5, the collision time is used for early warning decision making, the safety braking distance is used for emergency braking decision making, the corrected maximum braking deceleration serves as a full-force braking target value, and graded AEB control is achieved. According to the method, road surface factors are fully considered, vehicle safety can be guaranteed under different attachment conditions and slope road surfaces, and the braking stability is remarkably improved.

Description

Technical Field

[0001] The present application relates to new energy vehicles and active safety control, and particularly to a hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors. Background Art

[0002] Due to its large self-weight and size, and the complex and changeable driving environment of semi-trailers, the braking stability is poor and traffic accidents occur frequently. Essentially, the friction between the tire and the ground is the physical basis for a vehicle to complete braking, that is, road surface factors fundamentally restrict the braking distance and vehicle stability during braking. Therefore, the automatic emergency braking function of semi-trailers needs to consider road surface factors even more. However, most of the current automatic emergency braking applications for semi-trailers do not consider the influence of road surface factors.

[0003] In addition, the current automatic emergency braking can be divided into two types: a safety distance collision avoidance strategy based on the driving distance and a collision time collision avoidance strategy based on the driver's reaction characteristics, and most of them are independent of each other. Among them, the collision avoidance strategy based on the safety distance has better adaptability. However, at high speeds, the calculation deviation is large, the correction coefficient is difficult to obtain, and in the spatial domain, the driver's risk assessment is not accurate. The collision time collision avoidance strategy can more directly feedback the risk urgency to the driver, which is more in line with the driver's habits and can better ensure the driver's driving experience. However, its directness in risk assessment is weaker than that of the collision avoidance strategy based on the safety distance.

[0004] To further reduce traffic accidents and serious losses of semi-trailers, it is of great significance to carry out an AEB control strategy based on road surface factors and combining the safety distance-based and collision time-based AEB control strategies. Summary of the Invention

[0005] The purpose of the present application is to provide a hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors, which solves the problems that the current AEB control strategy for electric drive semi-trailers does not comprehensively consider road surface factors and the control strategies do not complement each other in advantages.

[0006] To achieve the above purpose, in the first aspect, the present application provides a hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors, and the method includes:

[0007] The vehicle obtains information about the vehicle ahead and road surface information in real time through sensors and high-precision maps, etc., and then calculates and corrects the road surface adhesion coefficient and determines the maximum slope limit in combination with the current state of the vehicle;

[0008] Based on fuzzy control, using the corrected road surface adhesion coefficient and slope information as inputs, and finally outputting a maximum braking deceleration correction factor;

[0009] Calculate the maximum braking deceleration for different driving conditions according to the quality of the road surface conditions and in combination with the maximum braking deceleration correction factor;

[0010] Dynamically calculate the safe braking distance and collision time according to the current vehicle state and in combination with the speed and distance of the vehicle ahead;

[0011] Use the collision time as the decision basis for the warning function of the AEB system, use the safe braking distance as the decision basis for the emergency braking function of the AEB, and use the corrected maximum braking deceleration as the target value when the AEB system brakes with full force. Considering the above factors, realize the hierarchical AEB control considering road surface factors.

[0012] Further, in one embodiment, the vehicle obtains information about the vehicle ahead and the road surface in real time through sensors and high-precision maps, etc., so as to calculate and correct the road surface adhesion coefficient and determine the maximum slope limit in combination with the current vehicle state, including:

[0013] Obtain key parameters such as the motion state of the target ahead, road slope information, and road surface friction coefficient through sensors and navigation maps, etc.;

[0014] Calculate the road surface adhesion coefficient according to the correction formula considering dynamic road surface factors such as friction coefficient, and determine the maximum slope limit in combination with road design specifications and its own vehicle type.

[0015] Further, in one embodiment, the fuzzy control takes the corrected road surface adhesion coefficient and slope information as inputs, and finally outputs the maximum braking deceleration correction factor, including:

[0016] Formulate fuzzy rules and input-output membership functions, and perform fuzzification, fuzzy decision-making, and defuzzification to finally obtain the maximum braking deceleration correction factor.

[0017] Further, in one embodiment, the calculation of the maximum braking deceleration for different driving conditions according to the quality of the road surface conditions and in combination with the maximum braking deceleration correction factor includes:

[0018] Classify the road surface according to the friction index: good, medium, poor;

[0019] Determine the reference deceleration value of the maximum deceleration on a good road surface according to the mean reference value of the maximum deceleration of the vehicle on a good road surface, and considering the safety requirements of commercial vehicle loading;

[0020] Calculate the maximum braking deceleration for different driving conditions by combining the maximum braking deceleration correction factor and the reference deceleration on a good road surface.

[0021] Further, in one embodiment, the dynamic calculation of the safe braking distance and collision time according to the current vehicle state and in combination with the speed and distance of the vehicle ahead includes:

[0022] Calculate the time to collision according to the second-order TTC model;

[0023] Calculate the safe braking distance according to the motion equation in combination with the motion state of the vehicle ahead and the distance to the vehicle ahead.

[0024] Further, in one embodiment, using the time to collision as the decision basis for the AEB system's warning function includes:

[0025] When it is detected that the time to collision is less than the first-level threshold, the AEB enters the first-level warning mode, and at this time, the vehicle gives a reminder to the driver in the form of a light signal. If the system detects that the driver has intervened manually and the time to collision is greater than the first-level threshold, the AEB automatically exits the first-level warning mode. If the driver does not respond in time in the first-level warning mode, then detect the road surface friction coefficient at this time. If the friction coefficient is less than the preset value, further detect the safe distance. If the safe distance is less than the first-level threshold, the AEB will automatically skip the second-level warning and enter the full braking mode. If the road surface friction coefficient is greater than the preset value at this time, the AEB will continue to make decisions based on the time to collision, that is, when the time to collision is less than the second-level threshold, the AEB enters the second-level warning mode and reminds the driver with a sound signal and a tactile signal of the steering wheel vibration. If the driver participates in braking during the second-level warning stage, the second-level warning mode will be automatically exited.

[0026] Further, in one embodiment, 7. Using the safe braking distance as the decision basis for the AEB emergency braking function and using the corrected maximum braking deceleration as the target value when the AEB system performs full braking, and realizing hierarchical AEB control considering road surface factors based on the above factors, including:

[0027] Using the corrected maximum braking deceleration as the target value when performing full braking, that is, the maximum braking deceleration multiplied by the maximum braking deceleration correction factor;

[0028] If the driver does not respond in time in the second-level warning mode, the system will directly make decisions based on the safe distance. When the road surface friction coefficient is not less than the preset value, if it is detected that the distance between the two vehicles is less than the first-level threshold of the safe distance, the vehicle will enter the partial braking mode until the vehicle itself stops completely or the relative speed of the two vehicles is 0. If it is detected during the partial braking process that the safe distance is further reduced and less than the set second-level threshold, the AEB will enter the full braking mode for braking until the vehicle itself stops completely or the relative speed of the two vehicles is 0.

[0029] Further, in one embodiment, the vehicle state includes: vehicle speed, acceleration, brake pedal opening, vehicle attitude information, and remaining battery power.

[0030] Second aspect, based on the above-mentioned hierarchical AEB control decision-making method considering road surface factors, the present application provides a hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors. The AEB control decision-making includes:

[0031] A safety distance collision avoidance strategy based on the driving distance. This strategy calculates the minimum safety distance required to avoid a collision between the vehicle and the target obstacle, and determines the specific working mode of AEB and the braking deceleration applied during emergency braking according to the comparison result with the preset safety distance threshold.

[0032] A time-to-collision collision avoidance strategy based on the driver's reaction characteristics. This strategy needs to calculate the time to collision (TTC) between the vehicle and the target ahead and compare it with the set threshold, and finally make decisions on the working mode of AEB and the target deceleration according to the comparison result.

[0033] The beneficial effects brought by the technical solutions provided in the embodiments of the present application include:

[0034] The present application calculates and corrects the road surface adhesion coefficient and the maximum gradient limit, and uses fuzzy control to output the maximum braking deceleration correction factor, so that the AEB system can accurately adjust the maximum braking deceleration according to different road surface conditions (good, medium, bad), effectively making up for the defect that traditional AEB does not fully consider road surface factors, improving the adaptability of the braking system to complex road conditions, and enhancing the braking stability and safety of the vehicle.

[0035] Integrate the advantages of the two collision avoidance strategies. The time to collision is used for early warning, intuitively reflecting the urgency of the risk and conforming to the driver's habits; the safe braking distance is used for emergency braking decision-making, providing a more accurate risk assessment. The two work together to achieve complementary advantages and improve the scientificity and rationality of the AEB system decision-making.

[0036] Innovatively design a hierarchical AEB control. By setting different thresholds and according to the driver's reaction and road surface conditions, it intelligently decides whether to skip the early warning and directly enter the full-power braking mode. This hierarchical control not only gives the driver enough intervention space, but also can intervene in time at a dangerous moment to ensure driving safety, while optimizing the driving experience and reducing unnecessary false triggers. Description of the Drawings

[0037] Figure 1 It is a flowchart of the hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors in the embodiments of the present application.

[0038] Figure 2 It is a flowchart of the hierarchical AEB control strategy considering road surface factors in the embodiments of the present application. Detailed Embodiments

[0039] To enable those skilled in the art to better understand the solution of this application, the following will clearly and completely describe the technical solution in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0040] To make the purpose, technical solution and advantages of this application clearer, the following will give a further detailed description of the embodiments of this application in conjunction with the accompanying drawings.

[0041] In a first aspect, an AEB control decision-making method for a motor-driven semi-trailer with road surface factors considered is provided in an embodiment of this application.

[0042] In one embodiment, as shown in Figure 1 the above method includes:

[0043] S1. The vehicle obtains information about the vehicle ahead and road surface information through sensors and high-precision maps, etc., and calculates the corrected adhesion coefficient and determines the maximum slope limit in combination with its own state;

[0044] S2. Taking the corrected adhesion coefficient and slope as inputs, the maximum braking deceleration correction factor is output through fuzzy control;

[0045] S3. According to the quality of the road surface conditions and the maximum braking deceleration correction factor, the maximum braking deceleration is calculated for different working conditions;

[0046] S4. According to the current state of the vehicle, the speed and distance of the vehicle ahead, the safe braking distance and the collision time are calculated;

[0047] S5. The collision time is used for early warning decision-making, the safe braking distance is used for emergency braking decision-making, and the corrected maximum braking deceleration is used as the full braking target value to achieve hierarchical AEB control.

[0048] In the embodiment of this application, by calculating the corrected road surface adhesion coefficient and the maximum slope limit, and using fuzzy control to output the maximum braking deceleration correction factor, the AEB system can accurately adjust the maximum braking deceleration according to different road surface conditions (good, medium, bad), effectively making up for the defect that traditional AEB does not fully consider road surface factors, improving the adaptability of the braking system to complex road conditions, and enhancing the braking stability and safety of the vehicle. By integrating the advantages of two collision avoidance strategies, the collision time is used for early warning, intuitively reflecting the urgency of the risk and conforming to the driver's habits; the safe braking distance is used for emergency braking decision-making, providing a more accurate risk assessment. The two work together to achieve complementary advantages and improve the scientificity and rationality of the AEB system decision-making.

[0049] Further, in one embodiment, in the above step S1, it includes:

[0050] S101. Obtain key parameters such as the motion state of the front target, road slope information, and road surface friction coefficient through sensors and navigation maps.

[0051] Among them, the motion state of the front target can be collected through various types of sensors, such as lidar, millimeter-wave radar, and vision cameras, to identify the target and estimate motion parameters;

[0052] Parameters such as road slope and road surface friction coefficient can be estimated through a variety of sensors such as acceleration sensors, wheel speed sensors, gyroscopes, etc., in combination with the global navigation system and high-precision maps.

[0053] S102. Calculate the road surface adhesion coefficient according to the correction formula considering road surface dynamic factors such as friction coefficient, and determine the maximum slope limit in combination with road design specifications and the vehicle model itself.

[0054] Among them, the correction formula for the road surface adhesion coefficient after correction is:

[0055]

[0056] In the formula: is the road surface adhesion coefficient after correction, is the road surface friction coefficient, is the correction coefficient, is the slip ratio, is the driving speed of the vehicle itself .

[0057] The determination of the maximum slope limit is as follows: First, according to the "Highway Route Design Specification" in China, it is mentioned that when the design speed is less than or equal to 80 km / h, the longitudinal slope of the transition slope section should not be greater than 3%; when the design speed is greater than 80 km / h, the longitudinal slope of the transition slope section should not be greater than 2.5%. In addition, in the continuous uphill or downhill sections of the over-mountain route of secondary highways, tertiary highways, and fourth-class highways, when the relative height difference is 200 - 500 m, the average longitudinal slope should not be greater than 5.5%; when the relative height difference is greater than 500 m, the average longitudinal slope should not be greater than 5%. The average longitudinal slope of any continuous 3 km section should preferably not be greater than 5.5%. In addition, referring to the "Highway Engineering Technical Standard" in China, the maximum longitudinal slope standard of expressways should meet the requirements in the following table:

[0058] Table 1 Maximum Longitudinal Slope Standard of Expressways

[0059]

[0060] In this embodiment, the semi-trailer under study is a goods transportation vehicle that mostly travels on highways. Considering the above relevant standards and specifications, it is believed that in most cases, the absolute value of the slope on the semi-trailer's driving route does not exceed 5%. That is, the maximum slope limit is determined to be 5%.

[0061] Further, in one embodiment, the acquisition of key parameters such as the motion state of the front target, road slope information, and road surface friction coefficient in the above step S1, as well as the determination of the maximum slope limit, can provide high-quality input for the subsequent process.

[0062] Further, in one embodiment, in the above step S2, it includes:

[0063] S201. Formulate fuzzy rules and input-output membership functions, and perform fuzzification, fuzzy decision-making, and defuzzification to finally obtain the maximum braking deceleration correction factor.

[0064] Among them, the fuzzy control takes the corrected road surface adhesion coefficient and slope information as input and the maximum deceleration correction factor as output, so as to complete the correction of the reference value of the maximum deceleration in combination with road surface factors. The basic working process of fuzzy control can be summarized into four key steps: input fuzzification, fuzzy rule inference, output defuzzification, and execution control. For this application, first, the corrected road surface adhesion coefficient, input slope, and output acceleration correction factor should be fuzzified.

[0065] Further, in one embodiment, in the above step S3, it includes:

[0066] S301. Classify the road surface according to the friction index: good, medium, and poor;

[0067] Among them, the road surface classification rules are as follows: When the friction index is less than or equal to 1 level, the vehicle has good anti-skid performance and can exert a relatively large braking deceleration during braking. At this time, the road surface is classified as good; when the friction value is between 1 level and 3 levels, although the vehicle still has a certain anti-skid performance at this time, the maximum braking deceleration that the vehicle can exert will be weakened to a certain extent. At this time, the road surface is classified as medium. When the friction index is greater than or equal to 3 levels, due to the deterioration of the vehicle's anti-skid performance and the increase in safety hazards during braking, the road surface is classified as poor. The relationship between the friction index and anti-skid performance, friction coefficient, and road surface conditions is shown in the following table:

[0068] Table 2 Relationship between friction index and anti-skid performance, friction coefficient, and road surface conditions

[0069]

[0070] S302. Determine the reference deceleration on a good road surface according to the average reference value of the maximum deceleration of the vehicle on a good road surface and considering the safety requirements of commercial vehicle cargo, and determine the reference deceleration on a good road surface;

[0071] Among them, the specific method for determining the reference acceleration on a good road surface is as follows: According to the deceleration-related data during the vehicle collision, it can be known that the average value of the maximum braking deceleration that the vehicle can exert on a good road surface is 0.72g. Considering that the semi-trailer has a large carrying capacity and a wide variety of transported goods, it is usually necessary to ensure the integrity of the goods. If the braking deceleration during braking is too large, it may cause relative displacement between the goods and the vehicle, thus posing a risk of damaging the goods. Moreover, if the vehicle is carrying dangerous goods such as steel coils and steel bars at this time, these items will move forward, threatening the safety of the driver in the cab. Therefore, the reference value of the deceleration during automatic emergency braking of the vehicle should not be selected too large. After comprehensive consideration, this application selects the reference value of the maximum braking deceleration of the semi-trailer during automatic emergency braking to be 0.65g.

[0072] S303. Calculate the maximum braking deceleration by combining the maximum braking deceleration correction factor and the reference deceleration on a good road surface for different working conditions.

[0073] Among them, the calculation method of the maximum braking deceleration for different working conditions is as follows: 1) When the road surface is good, the expression of the maximum braking deceleration is:

[0074]

[0075] In the formula, is the maximum braking deceleration that the vehicle can exert under the influence of the control strategy, is the acceleration correction factor determined by road surface factors, is the reference value of the maximum braking deceleration of the vehicle on a good road surface. Combining the above, this value is taken as 0.65g.

[0076] 2) When the road surface condition is relatively poor, that is, when the friction index is greater than or equal to 3 levels, the main factor restricting the vehicle's braking performance is the road surface. Therefore, the maximum braking deceleration of the vehicle should be formulated with the road surface factor as the core at this time. Combining the slope factor, the maximum braking deceleration that can be exerted under this road surface condition is:

[0077]

[0078] 3) When the road surface friction index is between 1 level and 3 levels, that is, the road surface condition is medium, although the vehicle can exert a certain braking deceleration, the road surface factor still restricts the vehicle's braking performance. Therefore, in this case, it is necessary to comprehensively consider the control strategy and the influence of the road surface on the vehicle's braking. Here, a safety factor , this factor is numerically between 0 and 1. The maximum braking deceleration that can be exerted under this road surface condition can be expressed as:

[0079]

[0080] In summary, on the basis of considering road surface factors, the maximum braking deceleration of the vehicle is as shown in the formula:

[0081]

[0082] Furthermore, in one embodiment, the dynamic calculation of the safe braking distance and the collision time according to the current vehicle state and in combination with the speed and distance of the vehicle ahead in the above-mentioned step S4 includes:

[0083] S401. Calculate the collision time according to the second-order TTC model;

[0084] The calculation formula of the second-order TTC model is as follows:

[0085]

[0086] S402. Calculate the safe braking distance according to the motion equation in combination with the motion state of the vehicle ahead and the distance to the vehicle ahead.

[0087] The specific method for calculating the safe braking distance is as follows: 1) If the target ahead is moving at a constant speed or is stationary, when the relative speed of the two vehicles is 0, it can be considered that the risk is eliminated and the braking state ends, then the safe distance calculation formula is as follows:

[0088]

[0089] In the formula, is the safe distance of the vehicle (m), is the reserved distance (m) when the speeds of the two vehicles are the same.

[0090] 2) When the target ahead is moving with uniform deceleration, the safe distance calculation formula is as follows:

[0091]

[0092] Furthermore, in one embodiment, in the above-mentioned step S5, using the collision time as the decision basis for the early warning function of the AEB system, using the safe braking distance as the decision basis for the emergency braking function of the AEB system, and using the corrected maximum braking deceleration as the target value when the AEB system performs full braking, includes:

[0093] S501. When the detected time to collision (TTC) is less than the first - level threshold, AEB enters the first - level warning mode. At this time, the vehicle reminds the driver in the form of light signals. If the system detects that the driver has intervened manually and the TTC is greater than the first - level threshold, AEB automatically exits the first - level warning mode. If the driver does not respond in time in the first - level warning mode, the road surface friction coefficient is detected at this time. If the friction coefficient is less than the preset value, the safety distance is further detected. If the safety distance is less than the first - level threshold, AEB will automatically skip the second - level warning and enter the full - braking mode. If the road surface friction coefficient is greater than the preset value at this time, AEB will continue to make decisions based on the TTC. That is, when the TTC is less than the second - level threshold, AEB enters the second - level warning mode and reminds the driver with sound signals and tactile signals of steering wheel vibration. If the driver participates in braking during the second - level warning stage, it automatically exits the second - level warning mode. If the driver still does not respond in time in the second - level warning mode, it enters S502.

[0094] S502. When the road surface friction coefficient is not less than the preset value, if the detected distance between two vehicles is less than the first - level threshold of the safety distance, the vehicle will enter the partial - braking mode and brake with a deceleration of 0.4g until the host vehicle stops completely or the relative speed of the two vehicles is 0. If it is detected during the partial - braking process that the safety distance is further reduced and less than the set second - level threshold, AEB will enter the full - braking mode and brake with the maximum braking deceleration until the host vehicle stops completely or the relative speed of the two vehicles is 0.

[0095] In the second aspect, the above - mentioned first - level threshold of TTC, second - level threshold of TTC, first - level threshold of safe braking distance, and second - level threshold of safe braking distance all have preset ranges. Specifically:

[0096] The first - level threshold of TTC is taken as 3.6 - 3.7 s, and the second - level threshold of TTC is taken as 2.8 - 2.9 s; the first - level threshold of the safe distance takes a value of , and the second - level threshold of the safe distance takes a value of 0.6 - 0.62 .

[0097] This application combines the characteristics of the collision - avoidance strategy based on the safe distance and the collision - avoidance strategy based on the time to collision. Then, it considers the influence of two factors, namely the road surface adhesion coefficient and the slope information, on the maximum braking intensity that the vehicle can exert. Finally, it formulates the AEB control strategy considering road surface factors. The AEB control strategy proposed in this application not only meets the requirements of relevant standards in terms of function, but also can ensure the safety of the vehicle on roads with different adhesion conditions and different slopes, further verifying the effectiveness and reliability of the control strategy in terms of function.

[0098] It should be noted that the serial numbers of the embodiments of this application above are only for description and do not represent the superiority or inferiority of the embodiments.

[0099] In the description of the specification, claims and the above-mentioned drawings of this application, the terms "comprising", "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products or devices. Descriptions such as "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequential order, nor do they limit that "first", "second" and "third" are different types.

[0100] In the description of the embodiments of this application, terms such as "exemplary", "for example" or "for instance" are used to indicate examples, illustrations or explanations. Any embodiment or design solution described as "exemplary", "for example" or "for instance" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary", "for example" or "for instance" is intended to present the relevant concepts in a specific manner.

[0101] In the description of the embodiments of this application, unless otherwise specified, " / " means "or". For example, S / B may mean S or B; "and / or" in the text is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, S and / or B may represent: S exists alone, S and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "a plurality of" means two or more than two.

[0102] In some processes described in the embodiments of this application, there are multiple operations or steps that appear in a specific order. However, it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of this application or may be executed in parallel. The serial numbers of the operations are only used to distinguish different operations, and the serial numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0103] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method.

[0104] The above are only the preferred embodiments of this application, and do not limit the patent scope of this application. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of this application by the same token.

Claims

1. A hierarchical AEB control decision-making method for electric drive semi-trailers considering road surface factors, characterized in that, The method includes: S1. The vehicle obtains information about the vehicle ahead and road surface information through sensors and high-precision maps, etc., and calculates the corrected adhesion coefficient and determines the maximum gradient limit in combination with its own state; S2. Using the corrected adhesion coefficient and gradient as inputs, the maximum braking deceleration correction factor is output through fuzzy control; S3. According to the quality of the road surface conditions and the maximum braking deceleration correction factor, the maximum braking deceleration is calculated for different working conditions; S4. According to the current state of the vehicle, the speed and distance of the vehicle ahead, the safe braking distance and the collision time are calculated; S5. The collision time is used for early warning decision-making, the safe braking distance is used for emergency braking decision-making, and the corrected maximum braking deceleration is used as the full braking target value to achieve hierarchical AEB control.

2. The graded AEB control decision-making method for an electric drive semi-trailer considering road surface factors as claimed in claim 1, wherein, The vehicle obtains information about the vehicle ahead and road surface information through sensors and high-precision maps, etc., and calculates the corrected adhesion coefficient and determines the maximum gradient limit in combination with its own state, including: 1) Obtain key parameters such as the motion state of the target ahead, road gradient information, and road surface friction coefficient through sensors and navigation maps, etc.; 2) Calculate the road surface adhesion coefficient according to the correction formula considering dynamic road surface factors such as friction coefficient, and determine the maximum gradient limit in combination with road design specifications and its own vehicle type.

3. The graded AEB control decision-making method for an electric drive semi-trailer considering road surface factors according to claim 1, characterized in that, Using the corrected adhesion coefficient and gradient as inputs, the maximum braking deceleration correction factor is output through fuzzy control, including: 1) Formulate fuzzy rules and input-output membership functions, and perform fuzzification, fuzzy decision-making, and defuzzification to finally obtain the maximum braking deceleration correction factor.

4. The hierarchical AEB control decision-making method for electric drive semi-trailers considering road surface factors according to claim 1, characterized in that, According to the quality of the road surface conditions and the maximum braking deceleration correction factor, the maximum braking deceleration is calculated for different working conditions, including: 1) Classify the road surface according to the friction index: good, medium, and bad; 2) Determine the reference value of the average maximum deceleration of the vehicle on a good road surface, and considering the safety requirements of commercial vehicle loading, determine the reference deceleration on a good road surface; 3) Combine the maximum braking deceleration correction factor and the reference deceleration on a good road surface to calculate the maximum braking deceleration for different working conditions.

5. The hierarchical AEB control decision-making method for electric drive semi-trailers considering road surface factors as described in claim 1, wherein, According to the current state of the vehicle, the speed and distance of the vehicle ahead, the safe braking distance and the collision time are calculated, including: 1) Calculate the collision time according to the second-order TTC model; 2) Calculate the safe braking distance according to the motion equation in combination with the motion state of the vehicle ahead and the distance to the vehicle ahead.

6. The hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors according to claim 1, characterized in that, Using the collision time for early warning decision-making includes: 1) When the detected collision time is less than the first - level threshold, AEB enters the first - level warning mode. At this time, the vehicle gives a reminder to the driver in the form of light signals; if the system detects that the collision time is greater than the first - level threshold after the driver's manual intervention, AEB automatically exits the first - level warning mode. If the driver does not respond in time in the first - level warning mode, then the road surface friction coefficient is detected at this time. If the friction coefficient is less than the preset value, the safety distance is further detected. If the safety distance is less than the first - level threshold, AEB will automatically skip the second - level warning and enter the full - force braking mode. If the road surface friction coefficient is greater than the preset value at this time, AEB will continue to make decisions based on the collision time. That is, when the collision time is less than the second - level threshold, AEB enters the second - level warning mode and reminds the driver with sound signals and tactile signals of the steering wheel vibration; in the second - level warning stage, if the driver participates in braking, it automatically exits the second - level warning mode.

7. The hierarchical AEB control decision-making method for an electric drive semi-trailer considering road surface factors as described in claim 1, characterized in that The safe braking distance is used for emergency braking decision - making. The corrected maximum braking deceleration is used as the full - force braking target value. The implementation of hierarchical AEB control includes: 1) Use the corrected maximum braking deceleration as the target value during full - force braking, that is, the maximum braking deceleration multiplied by the maximum braking deceleration correction factor; 2) If the driver does not respond in time in the second - level warning mode, the system will directly make decisions based on the safety distance; when the road surface friction coefficient is not less than the preset value, if the distance between the two vehicles is detected to be less than the first - level threshold of the safety distance, the vehicle will enter the partial braking mode until the own vehicle completely stops or the relative speed of the two vehicles is 0; if it is detected during partial braking that the safety distance is further reduced and less than the set second - level threshold, AEB will enter the full - force braking mode for braking until the own vehicle completely stops or the relative speed of the two vehicles is 0.

8. The hierarchical AEB control decision-making method considering road surface factors according to any one of claims 1-7, characterized in that, The vehicle state includes: vehicle speed, acceleration, brake pedal opening, vehicle attitude information, and remaining battery power.

9. The AEB control decision-making of a classification AEB control decision-making method considering road surface factors according to any one of claims 1-7, characterized in that, The AEB control decision includes: 1) A safety - distance collision - avoidance strategy based on the driving distance. This strategy calculates the minimum safety distance required to avoid a collision between the vehicle and the target obstacle, and determines the specific working mode of AEB and the braking deceleration applied during emergency braking according to the comparison result with the preset safety - distance threshold; 2) A collision - time collision - avoidance strategy based on the driver's reaction characteristics. This strategy needs to calculate the time to collision (TTC) between the vehicle and the target ahead and compare it with the set threshold, and finally make decisions on the working mode of AEB and the target deceleration according to the comparison result.

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