Disclosure of Invention
In order to solve the technical problem, the invention provides an intelligent vehicle braking and parking capacity testing method considering passenger comfort, which comprises the following steps of:
(1) constructing a test site, and determining a tested passenger and a tested automatic driving vehicle;
the test site should meet the following requirements:
the pavement is dry and has no obvious visible wet place;
the peak value adhesion coefficient between the test road surface and the test tire is more than 0.9;
the test pavement is straight and flat, has no obvious adverse conditions such as bulges, pits, cracks and the like, and has the horizontal flatness of less than 1 percent and the length of not less than 400 m;
in the test process, no vehicle or barrier can be arranged within 3m of two sides of the test road and within 25m in front of the static target vehicle;
the tested passengers determine the number of people, the sex ratio and the age distribution according to the sex and the age distribution ratio of the population in China, and the tested passengers also comprise tested persons with carsickness symptoms of different degrees.
(2) EstablishingSpeed condition of brake test: setting a plurality of different initial speeds u at fixed speed intervals in a certain initial speed interval
0(ii) a At maximum deceleration a
bmaxTo a minimum deceleration a
b minWithin the interval, a plurality of different braking decelerations a are set at a certain interval of the braking deceleration
bWherein the maximum deceleration a
bmaxNot exceeding the deceleration that the maximum braking force on the ground can provide, i.e.
Peak adhesion coefficient; minimum deceleration a
b minNot lower than the minimum braking deceleration specified by the national standard, i.e. a
b min≥a
ISO(ii) a Wherein, a
ISOThe minimum braking deceleration of the automobile cold test is specified for ISO 6597;
(3) in a test site, a tested passenger takes a tested automatic driving vehicle, and the process from the start of braking to the stop of the tested automatic driving vehicle is taken as test content to acquire the braking deceleration and the instantaneous running speed of the tested automatic driving vehicle in real time;
(4) in the test process, the comfort subjective feelings of each subject when the tested automatic driving vehicle performs the brake test with different brake decelerations are collected, wherein the comfort subjective feelings comprise four subjective evaluation indexes of 'very comfortable', 'more comfortable', 'less comfortable' and 'very uncomfortable', and the four subjective evaluation indexes are used as the corresponding initial speed u of the subject0And braking deceleration abThe comfort degree weighting coefficient w reflects four acquired subjective evaluation indexes of the subject by adjusting the weighting coefficient w, the higher the value of w is, the more important the data is in the curve fitting process, and in the test, the comfort degree and the value of w are in positive correlation;
(5) the value of the comfort weighting factor w is determined using Analytic Hierarchy Process (AHP):
for the subjective feeling of the comfort level acquired in the previous step, a reasonable judgment matrix is constructed through comparison of importance degrees between every two evaluation indexes to obtain a comparison judgment matrix, the judgment matrix is normalized and averaged in rows in sequence to obtain a weight vector, consistency inspection is carried out on the weight vector, and the weighting coefficients of the comfort levels corresponding to 'very comfortable', 'more comfortable', 'less comfortable' and 'very uncomfortable' can be obtained after the consistency inspection is met;
(6) based on discrete statistical data acquired and processed by a subject, combining with the weighting of a comfort weighting coefficient w of the subject, a weighted least square method is adopted as a curve fitting method to obtain an optimal braking deceleration curve, and the corresponding equation set is as follows:
in the formula, l is the acquired data volume; w is ai、u0iAnd abiComfort degree weighting coefficient, braking initial speed and braking deceleration of the ith group of data are respectively set; n is the optimum polynomial degree selected according to the fitting degree; a is0,a1,…,anFitting coefficients for the polynomial;
solving the above equation system can obtain the mathematical expression that the optimal braking deceleration changes with the initial speed:
acoft=ab=a0+a1u0+a2u0 2+…+anu0 n
in the formula, acoftFor optimal braking deceleration; u. of0Is the initial speed;
with acoftAs the evaluation basis of the passenger comfort degree, when the automatic driving vehicle adopts the deceleration a not more than the optimal braking deceleration acoftBraking deceleration abDuring braking, the vehicle is considered to meet the requirement of comfort level of passengers, otherwise, the vehicle is considered not to reach the comfort level index.
(7) Designing a test scene:
the braking process of the tested automatic driving vehicle in the test scene is divided into three parts, and the behavior nodes are respectively point A, B, C: test autonomous vehicle to designInitial velocity u0Automatically driving to a point A at a constant speed, and starting braking when the point A is reached; in the section from A to B, the braking force is continuously and linearly increased, and when the point B is reached, the braking force of the tested vehicle is increased to FpDeceleration is increased to abeAt which time the vehicle under test is at an instantaneous speed ueContinue to run, and ueIs greater than 0; the vehicle under test is at an instantaneous speed ueDeceleration abePassing through the point B to the point C, the braking force and the deceleration in the road sections from B to C are constant, and the speed u at the point Cc=0;
Selecting braking initial speed u according to vehicle type to be tested0Further determining the position A of three braking points on the test routeISO、AcomfortAnd Arisk:
If and only if the target deceleration
Time brake distance s
ACAt the minimum, this braking point is the most dangerous braking point, denoted A
riskBecause there is a great risk that the vehicle cannot be parked at the predetermined parking position if the vehicle takes a braking action after exceeding the predetermined parking position; when a is
be=a
ISOWhile, the braking distance s
AC=s
ACrangeReaching the maximum value in the national standard allowable range, the braking point is the braking point in the maximum allowable range and is marked as A
ISOThe starting of braking at this braking point is the maximum braking distance allowed by international standards; when the comfort of passengers is considered, the optimal braking deceleration a at the current test braking initial speed is obtained by the braking deceleration optimal curve
coftObtaining the corresponding braking distance s
ACcomfortAt the same time due to a
b=a
coft<a
bmaxKnowing its braking distance s
ACcomfortHas a value range of s
ACmin<s
ACcomfort<s
ACrangeThe braking point is marked as A
comfort;
(8) In the test scene, the automatic driving vehicle to be tested enters a test road section at a preset initial speed, and autonomously performs braking action, wherein the evaluation criteria are as follows:
braking behavior of vehicle to be testedIn AriskThe rear, braking action taking place at braking point AISOWhen the front or parking point exceeds the preset parking point C, the vehicle to be tested is considered to be incapable of meeting the requirement of the safety dimension, and the evaluation grade is recorded as unqualified;
the vehicle that awaits measuring can be in predetermineeing parking point C department braking parking, thinks to satisfy the requirement of safe dimension, further evaluates braking parking passenger comfort level:
the braking behavior of the vehicle to be tested occurs in AISOAnd AcomfortIn the meantime, the passenger experience dimension requirement is considered to be met, and the evaluation level is recorded as 'comfort';
the braking behavior of the vehicle to be tested occurs in AcomfortThen, the passenger experience dimension requirement is considered to be not satisfied, and the evaluation level is recorded as "uncomfortable".
Further, step (7) determines point A, B, C and braking point position A based on the following theoretical calculationISO、AcomfortAnd Arisk:
The brake braking process of the tested automatic driving vehicle is divided into three parts: the brake is acted, continuously braked and released;
1) in the brake application phase t1In the time period:
since the brake shoe is pulled by the rebound spring and a gap exists between the shoe and the brake drum, the time t 'is required for the brake shoe to contact the brake drum'1The ground braking force can only be activated and cause the vehicle to produce deceleration, hence period t'1The inner vehicle moves at constant speed t'1Velocity constant in the section is u0,t'1The distance traveled by the segment vehicle is s'1=u0t'1;
Time period t after brake application
1And the automatic driving vehicle makes an autonomous decision according to the test scene to ensure that the braking deceleration a of the vehicle
bFrom a
b0Linearly increasing to the required braking deceleration a
be(ii) a Due to the fact that
In the formula
So ═ du ═ ktdt, then
t
1At a time of vehicle speed of
Due to the fact that
Then
Get t ═ t ″)
1Distance of time period
From the above can be obtained at t
1Distance of section brake
2) During the continuous braking phase t2In the time period:
the braking force reaches a constant value F
peThe deceleration of the vehicle reaches a required value a
beAnd keeping constant uniform deceleration movement, the initial speed of the stage is u
eLast speed is zero and carry in u
eTo obtain t
2The braking distance of the segment is
From the above 1) and 2) the total braking distance obtainable is
Due to t
1' and t
1"very Small, obviously, a
beThe larger the total braking distance s is;
braking distance s from road A to road B
ABThe calculation method is
Braking distance S from road B to road C
BCThe calculation method is
Braking distance S from road A to road C
ACThe calculation method is
The invention has the beneficial effects that:
the invention provides an intelligent vehicle braking and parking testing method considering passenger comfort feeling aiming at the whole process of an automatic driving braking and parking scene, which considers two dimensions of safety and experience, adopts a curve fitting method of discrete data, combines the passenger subjective comfort degree and objective driving data acquired by tests, repeatedly tests and verifies sensitive people (test groups can find car sickness people), and finally obtains a braking deceleration optimal curve, aims to provide an evaluation quantification standard for evaluating the passenger comfort degree during braking of an automatic driving vehicle under the condition of considering the passenger comfort degree, and improves related test items relating to automatic driving and parking to the height of safety and comfort. Theoretical basis and technical support are provided for multi-dimensional evaluation of the braking and stopping performance of the automatic driving vehicle. The invention firstly solves the problems that the comfort level of a vehicle passenger has subjective characteristics and the individual difference exists, creatively adopts a weighted curve fitting mode to correlate subjective evaluation and objective indexes, and constructs an automatic driving braking and parking capability test scene considering the comfort level of the passenger by establishing a mathematical relation between a braking distance and braking deceleration in automatic driving and taking the position of a braking action as an evaluation index, so that the test efficiency is higher, the repeatability is stronger, the test cost is reduced, the quantitative evaluation of the comfort level of braking and parking is completed, and a unified and effective theoretical basis and research method are provided for the braking decision optimization of the automatic driving vehicle.
Detailed Description
The invention provides a method for testing the braking and parking capacity of an intelligent vehicle with consideration of the comfort of passengers, which comprises the following steps:
(2) constructing a test site, and determining a tested passenger and a tested automatic driving vehicle;
the test site should meet the following requirements:
the pavement is dry and has no obvious visible wet place;
the peak value adhesion coefficient between the test road surface and the test tire is more than 0.9;
the test pavement is straight and flat, has no obvious adverse conditions such as bulges, pits, cracks and the like, and has the horizontal flatness of less than 1 percent and the length of not less than 400 m;
in the test process, no vehicle or barrier can be arranged within 3m of two sides of the test road and within 25m in front of the static target vehicle;
the tested passengers determine the number of people, the sex ratio and the age distribution according to the sex and the age distribution ratio of the population in China, and also comprise the testees with car sickness symptoms of different degrees, because the experience of the passengers on the speed and the braking deceleration of the vehicle is more sensitive than that of the ordinary people; j panelists of different genders and ages were selected.
The intelligent vehicle to be tested needs to meet the requirement that the driving mileage is not higher than 5000 km; the fuel quantity before the test is more than 90% of the volume of the fuel tank; for new energy vehicles capable of being externally charged, the power storage battery is fully charged according to GB/T18385-20055.1 the day before the test; and for the new energy vehicle which cannot be externally charged, preparing a test according to the normal running state of the vehicle.
(2) Establishing speed conditions for the braking test: setting a plurality of different initial speeds u at fixed speed intervals in a certain initial speed interval
0(ii) a At maximum deceleration a
bmaxTo a minimum deceleration a
b minWithin the interval, a plurality of different braking decelerations a are set at a certain interval of the braking deceleration
bWherein the maximum deceleration a
bmaxNot exceeding the deceleration that the maximum braking force on the ground can provide, i.e.
Peak adhesion coefficient; minimum deceleration a
b minNot lower than the minimum braking deceleration specified by the national standard, i.e. a
b min≥a
ISO(ii) a Wherein, a
ISOThe minimum braking deceleration of the automobile cold test is specified for ISO 6597; and setting a group of m braking initial speeds according to the test scene and the requirements of the automatic driving vehicle to be tested, and setting a group of k braking decelerations in a reasonable interval.
(3) In a test site, a tested passenger takes a tested automatic driving vehicle, and the process from the start of braking to the stop of the tested automatic driving vehicle is taken as test content to acquire the braking deceleration and the instantaneous running speed of the tested automatic driving vehicle in real time;
(4) in the test process, the comfort subjective feelings of each subject when the tested automatic driving vehicle performs the brake test with different brake decelerations are collected, wherein the comfort subjective feelings comprise four subjective evaluation indexes of 'very comfortable', 'more comfortable', 'less comfortable' and 'very uncomfortable', and the four subjective evaluation indexes are used as the corresponding initial speed u of the subject0And braking deceleration abThe comfort degree weighting coefficient w reflects four acquired subjective evaluation indexes of the subject by adjusting the weighting coefficient w, the higher the value of w is, the more important the data is in the curve fitting process, and in the test, the comfort degree and the value of w are in positive correlation;
(5) the value of the comfort weighting factor w is determined using Analytic Hierarchy Process (AHP):
for the subjective feeling of the comfort level acquired in the previous step, a reasonable judgment matrix is constructed by comparing the importance degrees of every two evaluation indexes, and the result is shown in table 1.
TABLE 1 comparison of the degree of importance
Layer of criteria
|
Very comfortable
|
Is more comfortable
|
Is less comfortable
|
Is very uncomfortable
|
Very comfortable
|
1
|
3
|
7
|
9
|
Is more comfortable
|
1/3
|
1
|
5
|
7
|
Is less comfortable
|
1/7
|
1/5
|
1
|
3
|
Is very uncomfortable
|
1/9
|
1/7
|
1/3
|
1 |
The obtained comparison judgment matrix J is:
normalizing the judgment matrix J according to columns to obtain a matrix:
performing row average on the judgment matrix J to obtain a weight vector:
calculating the maximum characteristic root gamma of the judgment matrix J of the evaluation indexmax:
In order to ensure the logical consistency of the judgment ideas and ensure that the judgment ideas are coordinated and consistent without internal contradiction, the consistency is checked. The consistency index c.i. is:
by referring to the "average random consistency index c.r. value", when n is 4, c.r. is 0.9, so that
Therefore, the judgment result of the obtained comparison matrix is considered to be acceptable.
Thus, "very comfortable," "more comfortable," "less comfortable," and "very uncomfortable" are obtained with comfort weighting coefficients of 0.58, 0.29, 0.09, and 0.05.
(6) Based on discrete statistical data acquired and processed by a subject, combining with the weighting of a comfort weighting coefficient w of the subject, a weighted least square method is adopted as a curve fitting method to obtain an optimal braking deceleration curve, and the corresponding equation set is as follows:
in the formula, l is the acquired data volume; w is ai、u0iAnd abiComfort degree weighting coefficient, braking initial speed and braking deceleration of the ith group of data are respectively set; n is the optimum polynomial degree selected according to the fitting degree; a is0,a1,…,anFitting coefficients for the polynomial;
solving the above equation system can obtain the mathematical expression that the optimal braking deceleration changes with the initial speed:
acoft=ab=a0+a1u0+a2u0 2+…+anu0 n
in the formula, acoftFor optimal braking deceleration; u. of0Is the initial speed;
with acoftAs the evaluation basis of the passenger comfort degree, when the automatic driving vehicle adopts the deceleration a not more than the optimal braking deceleration acoftBraking deceleration abDuring braking, the vehicle is considered to meet the requirement of comfort level of passengers, otherwise, the vehicle is considered not to reach the comfort level index.
(7) Designing a test scene:
the conventional vehicle braking process is divided into 4 stages: the driver responds after receiving the signal, the brake acts, the brake is continuously braked and released, the perception, decision and execution operation time of the automatic driving vehicle to the signal are far shorter than the reaction time of the driver, the invention ignores the time consumption of the phase, and the brake braking process of the tested automatic driving vehicle is divided into three parts: the brake is acted, continuously braked and released; a simplified autonomous vehicle deceleration line graph is plotted as shown in fig. 1.
1) In the brake application phase t1In the time period:
since the brake shoe is pulled by the rebound spring and a gap exists between the shoe and the brake drum, the time t 'is required for the brake shoe to contact the brake drum'1The ground braking force can only be activated and cause the vehicle to produce deceleration, hence period t'1The inner vehicle moves at constant speed t'1Velocity constant in the section is u0,t'1The distance traveled by the segment vehicle is s'1=u0t'1;
Time period t after brake application
1And the automatic driving vehicle makes an autonomous decision according to the test scene to ensure that the braking deceleration a of the vehicle
bFrom a
b0Linearly increasing to the required braking deceleration a
be(ii) a Due to the fact that
In the formula
So ═ du ═ ktdt, then
t
1At a time of vehicle speed of
Due to the fact that
Then
Get t ═ t ″)
1Distance of time period
From the above can be obtained at t
1Distance of section brake
2) During the continuous braking phase t2In the time period:
the braking force reaches a constant value F
peThe deceleration of the vehicle reaches a required value a
beAnd keeping constant uniform deceleration movement, the initial speed of the stage is u
eLast speed is zero and carry in u
eTo obtain t
2The braking distance of the segment is
From the above 1) and 2) the total braking distance obtainable is
Due to t
1' and t
1"very Small, obviously, a
beThe larger the total braking distance s is;
the braking process of the tested autonomous driving vehicle in the test scenario is divided into three parts, as shown in fig. 2, behavior nodes are respectively points A, B, C: test autonomous vehicle to design initial speed u0Automatically driving to a point A at a constant speed, and starting braking when the point A is reached; in the section from A to B, the braking force is continuously and linearly increased, and when the point B is reached, the braking force of the tested vehicle is increased to FpDeceleration is increased to abeAt which time the vehicle under test is at an instantaneous speed ueContinue to run, and ue>0;
Braking distance s from road A to road B
ABThe calculation method is
The vehicle under test is at an instantaneous speed ueDeceleration abePassing through the point B to the point C, the braking force and the deceleration in the road sections from B to C are constant, and the speed u at the point Cc=0;
Braking distance S from road B to road C
BCThe calculation method is
Braking distance S from road A to road C
ACThe calculation method is
Selecting braking initial speed u according to vehicle type to be tested0Further determining the position A of three braking points on the test routeISO、AcomfortAnd Arisk:
If and only if the target deceleration
Time brake distance s
ACAt the minimum, this braking point is the most dangerous braking point, denoted A
riskBecause there is a great risk that the vehicle cannot be parked at the predetermined parking position if the vehicle takes a braking action after exceeding the predetermined parking position; when a is
be=a
ISOWhile, the braking distance s
AC=s
ACrangeReaching the maximum value in the national standard allowable range, the braking point is the braking point in the maximum allowable range and is marked as A
ISOThe starting of braking at this braking point is the maximum braking distance allowed by international standards; when the comfort of passengers is considered, the optimal braking deceleration a at the current test braking initial speed is obtained by the braking deceleration optimal curve
coftObtaining the corresponding braking distance s
ACcomfortAt the same time due to a
b=a
coft<a
bmaxKnowing its braking distance s
ACcomfortHas a value range of s
ACmin<s
ACcomfort<s
ACrangeThe braking point is marked as A
comfort(ii) a The schematic diagram of the stopping point of the test scene is obtained as shown in the attached figure 3.
(8) And after the state of the vehicle to be tested is confirmed, starting to perform the autonomous braking parking test. In the test scene, the automatic driving vehicle to be tested enters a test road section at a preset initial speed, braking behavior is automatically carried out, and safety and experience two dimensions of the automatic driving vehicle to be tested in braking and parking are evaluated according to the following evaluation criteria:
the braking behavior of the vehicle to be tested occurs in AriskThe rear, braking action taking place at braking point AISOWhen the front or parking point exceeds the preset parking point C, the vehicle to be tested is considered to be incapable of meeting the requirement of the safety dimension, and the evaluation grade is recorded as unqualified;
the vehicle that awaits measuring can be in predetermineeing parking point C department braking parking, thinks to satisfy the requirement of safe dimension, further evaluates braking parking passenger comfort level:
the braking behavior of the vehicle to be tested occurs in AISOAnd AcomfortIn the meantime, the passenger experience dimension requirement is considered to be met, and the evaluation level is recorded as 'comfort';
the braking behavior of the vehicle to be tested occurs in AcomfortThen, the passenger experience dimension requirement is considered to be not satisfied, and the evaluation level is recorded as "uncomfortable".