CN110293972B - Method for determining road adhesion grade for braking distance compensation - Google Patents
Method for determining road adhesion grade for braking distance compensation Download PDFInfo
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- CN110293972B CN110293972B CN201910512144.8A CN201910512144A CN110293972B CN 110293972 B CN110293972 B CN 110293972B CN 201910512144 A CN201910512144 A CN 201910512144A CN 110293972 B CN110293972 B CN 110293972B
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- adhesion grade
- road
- braking distance
- condition
- road adhesion
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
- B60T8/1763—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to the coefficient of friction between the wheels and the ground surface
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
- B60W40/02—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
- B60W40/06—Road conditions
- B60W40/064—Degree of grip
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
- B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
- B60W40/105—Speed
Abstract
The invention discloses a method for determining road adhesion grade for braking distance compensation, which comprises the following steps: under the condition that the braking distance compensation condition is met, if the brake pedal is stepped and the anti-lock function is triggered, the controller determines a first road adhesion grade according to the master cylinder pressure, then the first road adhesion grade is used as the current road adhesion grade, and the driving mileage starts to be calculated; if the accelerator pedal is in a normal state and the starting anti-skid function is triggered, the controller determines a second road adhesion grade according to the opening degree of the accelerator pedal, then takes the second road adhesion grade as the current road adhesion grade, and starts to calculate the driving mileage; if the brake pedal is not stepped or the anti-lock function is not triggered, and the accelerator pedal is not in a normal state or the starting anti-skid function is not triggered, the controller takes 'normal' as the current road adhesion grade when the driving mileage is greater than the set mileage threshold value. The invention can simply, conveniently and quickly determine the current road adhesion grade.
Description
Technical Field
The invention belongs to the field of low-speed auxiliary driving systems, and particularly relates to a method for determining a road adhesion grade for braking distance compensation.
Background
In the low-speed driving auxiliary system, the automatic emergency braking function can perform emergency braking aiming at the relative relation between the vehicle and the obstacle under 10km/h, so as to avoid collision. The influence of different road conditions on the system needs to be considered, and particularly for northern ice and snow road surfaces, the road surface adhesion coefficient is small, and wheel locking or vehicle starting and slipping are easy to occur. On a road surface with poor adhesion, the braking distance of the vehicle is long, the deviation from the braking distance of a good road surface is large, and if the good road surface control parameters are still used, the collision is easy to occur. At present, the problem is generally solved by a brake controller which calculates specific road adhesion coefficients according to parameters of an engine, a transmission and a brake system; the method needs to collect parameters of an engine, a transmission, a braking system, a vehicle, a steering system and other systems, is complex in calculation, and mainly aims at a high-speed lower vehicle body stability control system; however, limited to the division of responsibility problem, brake system manufacturers are reluctant to open the parameters to the host plant for application to autonomous driving, while the numerous parameters and complex computational strategies of each system require long-term accumulation and extensive matching tests.
Disclosure of Invention
The object of the present invention is to provide a simple method for determining a road adhesion level for braking distance compensation in order to quickly determine a road adhesion level for braking distance compensation.
The method for determining the road adhesion grade for braking distance compensation comprises the following steps:
under the condition that the braking distance compensation condition is met, if the brake pedal is stepped and an anti-lock function is triggered, the controller determines a first road adhesion grade according to the master cylinder pressure (the side surface reflects the opening degree of the brake pedal), then the first road adhesion grade is used as the current road adhesion grade (namely the first road adhesion grade is used as the road adhesion grade for braking distance compensation at present), and the driving mileage is calculated; under the condition of meeting the braking distance compensation condition, if the brake pedal is not stepped or the anti-lock function is not triggered, the accelerator pedal is in a normal state and the starting anti-skid function is triggered, the controller determines a second road adhesion grade according to the opening degree (reflecting the acceleration force) of the accelerator pedal, then takes the second road adhesion grade as the current road adhesion grade (namely, takes the second road adhesion grade as the road adhesion grade currently used for braking distance compensation), and starts to calculate the driving mileage; under the condition of meeting the braking distance compensation condition, if the brake pedal is not stepped on or the anti-lock function is not triggered, and the accelerator pedal is not in a normal state or the starting anti-skid function is not triggered, when the driving distance is greater than a set mileage threshold value, the controller takes 'normal' as the current road surface adhesion grade (namely 'normal' as the current road surface adhesion grade for braking distance compensation), which indicates that the vehicle does not have anti-lock or starting anti-skid in the mileage, considers that the vehicle has already driven the road condition corresponding to the current road surface adhesion grade, and recovers the 'normal' road surface adhesion grade; in the case where the braking distance compensation condition is not satisfied, the controller regards "normal" as the current road surface adhesion level (i.e., regards "normal" as the road surface adhesion level currently used for braking distance compensation).
If the environment temperature is less than or equal to the set temperature threshold value and the vehicle speed is less than or equal to the set speed threshold value, the braking distance compensation condition is met; if the environment temperature is greater than the set temperature threshold value or the vehicle speed is greater than the set speed threshold value, the braking distance compensation condition is not met. The condition of mistakenly identifying the road adhesion grade can be avoided by taking the ambient temperature and the vehicle speed as the braking distance compensation conditions.
The invention divides the road surface adhesion grade into: normal, good, medium, and poor 4 grades. The road surface adhesion level is related to the magnitude of the master cylinder pressure at the time of the activation of the antilock function, and is related to the magnitude of the accelerator pedal opening at the time of the activation of the starting antiskid function. If the anti-lock function is triggered when the stepping degree of the brake pedal is very small (namely the pressure of the master cylinder is very small), the road adhesion grade can be defined as 'poor', and the subsequent grade is adjusted similarly along with the pressure value of the master cylinder; if the starting antiskid function is triggered when the opening degree of the accelerator pedal is very small, the road adhesion grade can be defined as 'poor', and the subsequent grade is adjusted similarly along with the opening degree of the accelerator pedal.
Preferably, the controller queries a first road adhesion grade table according to the master cylinder pressure to obtain the first road adhesion grade; the controller inquires a second road surface adhesion grade table according to the opening degree of an accelerator pedal to obtain the second road surface adhesion grade; wherein the first road adhesion rating table is: under the condition of meeting the braking distance compensation condition, a corresponding relation table (namely a corresponding relation table between the magnitude of the master cylinder pressure and the normal, good, medium and poor states) of the master cylinder pressure and the first road adhesion grade when the anti-lock function is triggered and calibrated through a road condition test; the second road surface adhesion grade table is as follows: and under the condition of meeting the braking distance compensation condition, a corresponding relation table (namely a corresponding relation table between the opening degree of the accelerator pedal and normal, good, medium and poor conditions) of the opening degree of the accelerator pedal and the adhesion grade of the second road surface when the starting antiskid function is triggered is calibrated through a road condition test.
According to the driving habits of a driver for operating an accelerator pedal and a brake pedal, the invention determines the road adhesion grade of the road surface on which the vehicle is positioned by using the existing signals of the accelerator pedal, the brake pedal, the master cylinder pressure, the vehicle speed, the ambient temperature and the like and combining the corresponding anti-skid and anti-lock function activation (triggering) states, thereby omitting complex calculations of an engine, a speed changer, a braking system, vehicle dynamics and the like.
Drawings
FIG. 1 is a flow chart of the present invention.
Fig. 2 is a diagram illustrating the effect of the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
The invention divides the road surface adhesion grade into: normal, good, medium, and poor 4 grades. The road surface adhesion level is related to the magnitude of the master cylinder pressure at the time of the activation of the antilock function, and is related to the magnitude of the accelerator pedal opening at the time of the activation of the starting antiskid function. If the anti-lock function is triggered when the stepping degree of the brake pedal is very small (namely the pressure of the master cylinder is very small), the road adhesion grade can be defined as 'poor', and the subsequent grade is adjusted similarly along with the pressure value of the master cylinder; if the starting antiskid function is triggered when the opening degree of the accelerator pedal is very small, the road adhesion grade can be defined as 'poor', and the subsequent grade is adjusted similarly along with the opening degree of the accelerator pedal.
The method for determining a road surface adhesion level for braking distance compensation as shown in fig. 1 includes:
the controller judges according to the environment temperature and the vehicle speed, if the environment temperature is less than or equal to a set temperature threshold value (such as minus 10 ℃) and the vehicle speed is less than or equal to a set speed threshold value (such as 10 km/h), the controller executes the second step, otherwise, the normal is taken as the current road surface adhesion grade, and then the method is finished.
And secondly, judging whether the brake pedal is stepped and the anti-lock function is triggered by the controller, if so, executing the third step, otherwise, executing the fifth step.
Thirdly, the controller inquires a first road adhesion grade table according to the master cylinder pressure to obtain a first road adhesion grade, and then the fourth step is executed; wherein, the first road adhesion grade table is as follows: and under the conditions that the ambient temperature is less than or equal to the set temperature threshold and the vehicle speed is less than or equal to the set speed threshold, the corresponding relation table (namely the corresponding relation table of the master cylinder pressure and the normal, good, medium and poor) of the master cylinder pressure and the first road adhesion grade is calibrated when the anti-lock function is triggered through the road condition test.
And fourthly, the controller takes the first road adhesion grade as the current road adhesion grade (namely, the first road adhesion grade is identified as the current road adhesion grade), starts to calculate the driving mileage and then ends.
And fifthly, judging whether the accelerator pedal is in a normal state and the starting antiskid function is triggered by the controller, if so, executing the sixth step, otherwise, executing the eighth step.
Sixthly, the controller queries a second road adhesion grade table according to the opening degree of the accelerator pedal to obtain a second road adhesion grade, and then the seventh step is executed; wherein the second road surface adhesion grade table is as follows: and under the condition that the environmental temperature is less than or equal to the set temperature threshold value and the vehicle speed is less than or equal to the set speed threshold value, the corresponding relation table (namely the corresponding relation table of the size of the opening degree of the accelerator pedal and the normal, good, medium and poor) of the opening degree of the accelerator pedal and the adhesion grade of the second road surface when the starting anti-skid function is triggered is calibrated through the road condition test.
And seventhly, taking the second road adhesion grade as the current road adhesion grade by the controller (namely identifying the second road adhesion grade as the current road adhesion grade), starting to calculate the driving mileage, and ending.
And eighthly, judging whether the traveled mileage is greater than a set mileage threshold (such as 800 m) by the controller, if so, executing the ninth step, and if not, finishing.
And ninthly, the controller takes the 'normal' as the current road adhesion grade (namely, identifies the 'normal' as the current road adhesion grade), indicates that the vehicle does not have anti-lock or anti-skid starting within the mileage, considers that the vehicle has already driven out of the road condition corresponding to the current road adhesion grade, recovers the 'normal' road adhesion grade, and then ends.
Fig. 2 is a diagram showing the effect of the present invention in a practical application in a certain type of vehicle, in which the anti-lock function state 1, the starting anti-skid function state 2, the master cylinder pressure 3, the accelerator pedal opening 4, and the road surface adhesion level 5 are associated with time, and "1" in the road surface adhesion level 5 indicates that the road surface adhesion level is "normal", "2" indicates that the road surface adhesion level is "good", "3" indicates that the road surface adhesion level is "medium", and "4" indicates that the road surface adhesion level is "poor". As can be seen from the figure, the anti-lock function and the starting anti-skid function were not triggered for 40 seconds, and the current road adhesion level was identified as "1"; at 40s, when the master cylinder pressure is about 20bar, the anti-lock function is triggered, and the current road adhesion level is recognized as "2"; at 80s, the anti-lock function is triggered again, and the current road adhesion level remains unchanged and is still identified as "2"; at 95s, when the opening degree of the accelerator pedal is smaller than 10%, the starting antiskid function is triggered, and the current road surface adhesion level is identified as '3'; at 105s, the start antiskid function is triggered again, but the road adhesion level is unchanged and still recognized as "3"; at 145s, the anti-lock function is triggered, and the current road adhesion level is recognized as "2"; at 161s, the starting antiskid function is triggered, and the current road surface adhesion level is recognized as "3".
Claims (3)
1. A method for determining a road adhesion level for braking distance compensation, characterized in that the method comprises:
under the condition that the braking distance compensation condition is met, if the brake pedal is stepped and the anti-lock function is triggered, the controller determines a first road adhesion grade according to the master cylinder pressure, then the first road adhesion grade is used as the current road adhesion grade, and the driving mileage starts to be calculated; under the condition of meeting the braking distance compensation condition, if the brake pedal is not stepped or the anti-lock function is not triggered, the accelerator pedal is in a normal state and the starting anti-skid function is triggered, the controller determines the second road adhesion grade according to the opening degree of the accelerator pedal, then takes the second road adhesion grade as the current road adhesion grade and starts to calculate the driving mileage; under the condition of meeting the braking distance compensation condition, if the brake pedal is not stepped or the anti-lock function is not triggered, and the accelerator pedal is not in a normal state or the starting anti-skid function is not triggered, the controller takes the normal as the current road adhesion grade when the driving range is greater than the set range threshold; in the case where the braking distance compensation condition is not satisfied, the controller takes "normal" as the current road surface attachment level.
2. The method for determining a road surface adhesion level for braking distance compensation according to claim 1, characterized in that: if the environment temperature is less than or equal to the set temperature threshold value and the vehicle speed is less than or equal to the set speed threshold value, the braking distance compensation condition is met; if the environment temperature is greater than the set temperature threshold value or the vehicle speed is greater than the set speed threshold value, the braking distance compensation condition is not met.
3. The method for determining a road surface adhesion level for braking distance compensation according to claim 1 or 2, characterized in that: the controller inquires a first road adhesion grade table according to the master cylinder pressure to obtain a first road adhesion grade; the controller inquires a second road surface adhesion grade table according to the opening degree of an accelerator pedal to obtain the second road surface adhesion grade; wherein the first road adhesion rating table is: under the condition of meeting the braking distance compensation condition, a corresponding relation table of master cylinder pressure and first road adhesion grade when an anti-lock function is triggered is calibrated through road condition test; the second road surface adhesion grade table is as follows: and under the condition of meeting the braking distance compensation condition, the corresponding relation table of the opening degree of the accelerator pedal and the adhesion grade of the second road surface when the starting antiskid function is triggered is calibrated through the road condition test.
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| CN201910512144.8A CN110293972B (en) | 2019-06-13 | 2019-06-13 | Method for determining road adhesion grade for braking distance compensation |
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| CN201910512144.8A CN110293972B (en) | 2019-06-13 | 2019-06-13 | Method for determining road adhesion grade for braking distance compensation |
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| CN110293972B true CN110293972B (en) | 2021-04-06 |
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| CN112298135B (en) * | 2020-10-30 | 2022-07-08 | 重庆长安汽车股份有限公司 | Vehicle braking distance optimization method |
| CN112590785B (en) * | 2020-12-31 | 2022-08-09 | 东风小康汽车有限公司重庆分公司 | Vehicle braking method and system |
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| CN102114840A (en) * | 2011-01-20 | 2011-07-06 | 浙江吉利汽车研究院有限公司 | Driving safety control device on road surface change |
| CN108045376B (en) * | 2017-11-30 | 2019-10-25 | 广州小鹏汽车科技有限公司 | A kind of control method for vehicle based on road surface adhesive ability, system and automobile |
| CN109466558B (en) * | 2018-10-26 | 2020-08-04 | 重庆邮电大学 | Road adhesion coefficient estimation method based on EKF (extended Kalman Filter) and BP (Back propagation) neural network |
| CN109733410A (en) * | 2018-12-21 | 2019-05-10 | 浙江万安科技股份有限公司 | A kind of real-time pavement identification method of ABS and system |
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Application publication date: 20191001 Assignee: CHONGQING CHANGAN NEW ENERGY AUTOMOBILE TECHNOLOGY Co.,Ltd. Assignor: Chongqing Changan Automobile Co.,Ltd. Contract record no.: X2021500000014 Denomination of invention: A method for determining pavement adhesion grade for braking distance compensation Granted publication date: 20210406 License type: Common License Record date: 20211014 |