CN114397119A - High-precision automobile and automobile train steering test method and system - Google Patents
High-precision automobile and automobile train steering test method and system Download PDFInfo
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- CN114397119A CN114397119A CN202210042733.6A CN202210042733A CN114397119A CN 114397119 A CN114397119 A CN 114397119A CN 202210042733 A CN202210042733 A CN 202210042733A CN 114397119 A CN114397119 A CN 114397119A
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Abstract
The application relates to a high-precision automobile and automobile train steering test method and system, which relate to the technical field of vehicle safety and comprise the following steps: steering a running vehicle on a test field to obtain a section of initial arc-shaped track and an initial turning radius thereof; if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle; keeping the target corner to continue steering and driving to a driving-away position, and forming a target arc-shaped track; returning to the positive direction disk, and stopping after linearly driving for a certain distance from the driving position; in the straight-line driving process, acquiring a first driving track and a second driving track of a first measuring point and a second measuring point on a vehicle; fitting the first travel trajectory to a tangent; and calculating the maximum distance between the second running track and the tangent line, and taking the maximum distance as the driving-off outward swinging value of the vehicle.
Description
Technical Field
The application relates to the technical field of vehicle safety, in particular to a high-precision automobile and automobile train steering test method and system.
Background
According to the regulation of GB17675-2021 basic requirements for automobile steering system, automobiles and automobile trains are required to run according to the track specified by the standard, parameters such as steering time, steering force, channel width, steering radius of a certain point on the automobile, driving-off swing value and the like in the running process of the automobile are measured, higher requirements are provided for the turning radius of a steering circle, the speed and the running route of the automobile, and evaluation indexes of the steering performance of the automobile are greatly changed, and in addition to the requirement of measuring the steering force and the steering time of a steering wheel, newly increased measurement results comprise: the variation of the turning radius, the width of the passage, the driving-off swing value and the like of the running vehicle, so whether the vehicle can run according to the track tracking required by the standard or not in the test process has great influence on the test result.
Referring to fig. 1, taking the newly-increased driving-away sway value test of the trailer and the train as an example, when the train is required to drive away from a steering circle with a radius of 25m at a speed of 25km/h, the driving-away sway value T of any part of the trailer is less than or equal to 0.5m within a range of 40m (from the tail end of the trailer) of a tangent line with a driving-away starting point as a tangent point along the tractor, namely the projection of any part of the trailer on the ground cannot exceed 0.5m of the tangent line of the steering circle with the radius of 25 m.
The test is taken as a mandatory safety detection project, and causes great trouble to enterprise research and development verification and regulation detection. And because the test device is a newly developed test item, a mature and credible detection device and a detection method are unavailable. At present, the test is carried out by referring to a water mark method and a quartz stroke line method, wherein the water mark method and the quartz stroke line method are used for drawing a circle with the radius of 25 meters and a straight line tangent to the circle on the ground, a mark post or a water spraying device is arranged on a vehicle, then the mark post of the vehicle runs along the circle on the ground, and returns to a positive direction disk when the mark post runs to a tangent point, so that the vehicle runs out of the circle along the tangent line.
When the method is adopted to carry out the test, a driver drives the vehicle and has several difficulties:
1. marked lines need to be drawn on the ground, and the field is limited.
2. The test vehicle speed is higher, the traditional water mark method is greatly influenced by the wind speed, and a pen is easy to break by adopting a quartz stroke line method at a higher vehicle speed, so that continuous marks cannot be left on the ground.
3. The test speed is high, the foremost outermost measuring point of the vehicle and the rearmost outermost measuring point on the same side of the vehicle are difficult to observe outside the sight line of a driver, the driver cannot see a marked line drawn on the ground close to the vehicle body, the foremost outermost measuring point needs to run along a steering circle with the radius of 25m in the test process, the error of running around the circle is large, and the repeatability is poor.
4. When the vehicle is driven out along the tangent line, the sight of a driver is blocked due to the fact that the vehicle speed is high, the driver is difficult to accurately drive out from the tangent point, the distance between the track of the last outermost measurement point and the tangent line exceeds a driving-out swing value, the test error is large, and the data reliability cannot be guaranteed.
5. The speed of a motor vehicle is high, and ground personnel can't in time command, and the driver not only needs to observe the marking, but also needs to carry out quick driving operation, and the very long inefficiency of experimental time spent, it is very high to driver's requirement, and safety can't guarantee in the experiment.
Disclosure of Invention
The embodiment of the application provides a high-precision automobile and automobile train steering test method and system, which aim to solve the problems that in the related art, a driver is limited by a visual angle when driving, the contact ratio of a vehicle and a marking line is difficult to accurately observe, the tracking difficulty is large, and the repeatability and the accuracy of vehicle tracking driving are difficult to guarantee.
In a first aspect, a high-precision automobile and automobile train steering test method is provided, which comprises the following steps:
steering a running vehicle on a test field to obtain a section of initial arc-shaped track;
calculating the initial turning radius of the initial arc-shaped track;
if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle;
keeping the target corner to continue steering to stop steering, simultaneously forming a target arc-shaped track, and taking a stop position as a driving-away position;
the steering wheel returns, and stops after the vehicle travels a certain distance in a straight line from the driving position;
in the straight-line driving process, acquiring a first driving track and a second driving track of a first measuring point and a second measuring point on a vehicle; the first measuring point and the second measuring point are respectively arranged at the foremost and outmost positions and the rearmost and outmost positions of the vehicle;
fitting the first travel track into a tangent line, wherein the tangent line passes through the travel-away position and is tangent to the target arc-shaped track;
and calculating the maximum distance between the second running track and the tangent line, and taking the maximum distance as a running-away outer swing value of the vehicle.
In some embodiments:
taking the turning radius of the arc-shaped track of the vehicle running within a first preset time length as an instant radius;
roughly adjusting the turning angle of the steering wheel by taking the instant radius as a reference;
taking the turning radius of an arc-shaped track of a vehicle running within a second preset time length as a stable radius, wherein the second preset time length is longer than the first preset time length;
finely adjusting the turning angle of the steering wheel by taking the stable radius as a reference;
and taking the steering wheel corner as a target corner at the moment until the stable radius is within the preset target radius range.
In some embodiments, the instantaneous radius and the stable radius are calculated using a recursive average filtering method.
In some embodiments, calculating the instant radius by using a recursive average filtering method specifically includes the following steps:
continuously acquiring s plane coordinates on an arc track of a vehicle running within a first preset time length, and taking the s plane coordinates as a first queue;
the vehicle continues to run to obtain a new arc-shaped track, a new coordinate obtained on the new arc-shaped track is placed at the tail of the queue, and a coordinate of the head of the previous first queue is thrown away to serve as a new first queue;
the turn radius of the new first queue is calculated and taken as the instant radius.
In some embodiments, calculating the stable radius by using a recursive average filtering method specifically includes the following steps:
continuously acquiring t plane coordinates on an arc-shaped track of the vehicle running within a second preset time length, and taking the t plane coordinates as a second queue; wherein t > s;
the vehicle continues to run, a new arc-shaped track is obtained again, a new coordinate obtained on the new arc-shaped track is placed at the tail of the queue, and a coordinate of the head of the previous second queue is thrown away to serve as a new second queue;
and calculating the turning radius of the new second queue, and taking the turning radius as a stable radius.
In some embodiments, calculating the initial turning radius of the initial arc trajectory specifically includes the following steps:
fitting the initial arc-shaped track to obtain a fitting circle; recording the radius of the fitting circle as R and the coordinates of the circle center as (A, B);
acquiring n plane coordinates of the first measuring point on the initial arc-shaped track, and recording the plane coordinate of the first measuring point acquired at the ith time as (x)i，yi) (ii) a Wherein, i is 1, 2.. n, n represents the number of acquisitions per cycle;
calculating the distance d from the first measuring point acquired at the ith time to the center of the fitting circleiSquared difference σ with radius R of the fitted circleiThe formula is as follows:
order:
then:
determining the parameters a, b, c such that the value of Q (a, b, c) is minimal, wherein:
when the minimum value of Q (a, b, c) is found by finding the partial derivatives for a, b, c and setting the partial derivatives to 0, respectively:
simplifying the three formulas and solving a ternary linear equation set;
order:
D＝(n∑xiyi-∑xi∑yi)
then a, b, c are as follows:
finally, obtaining parameters of the fitting circle:
and taking R as the initial turning radius.
In some embodiments, the acquiring n plane coordinates of the first measuring point on the initial arc-shaped track specifically includes the following steps:
installing a GPS on the first measuring point to obtain a first GPS coordinate of the first measuring point on the initial arc-shaped track;
taking the GPS coordinate as an origin of a coordinate system of the test site, and calculating to obtain an X axis and a Y axis of the coordinate system according to an east axis and a north axis of the GPS coordinate system;
and converting the n GPS coordinates of the first measuring point on the initial arc-shaped track into plane coordinates according to a coordinate system of a test field.
In some embodiments, fitting the first travel track to a tangent line specifically includes the following steps:
let the tangent equation be: y ═ ax + b
Obtaining the coordinates of m first track points on the first traveling track, and recording the plane coordinate of the jth first track point as (x)j，yj)，j＝1,2,3......m；
And calculating the sum of squares of the distance from the m first track points to the straight line y, wherein the sum is equal to ax and b, and is recorded as E (a and b), wherein:
E(a,b)＝∑(yj-axj-b)2
when E (a, b) is minimum, corresponding coefficients a and b are calculated, and the specific steps are as follows:
and respectively calculating the partial derivatives of a and b, and setting the partial derivative value to be 0, namely:
obtaining a system of linear equations of two in relation to a and b from the above formula, and solving the system of equations;
order:
E＝∑xj
F＝∑xjyj
G＝∑yj
convert the above system of linear equations into
a×D+b×E-F＝0
a×E+m×b-G＝0
The equation can be solved:
in some embodiments, calculating a maximum distance between the second driving track and the tangent line, and using the maximum distance as a driving-away yaw value of the vehicle specifically includes the following steps:
obtaining coordinates of q second track points positioned on the outer side of the tangent line on the second running track;
calculating the distance between all the second track points and the tangent line;
taking the maximum value of all the distances as a driving-away outer swing value of the vehicle;
calculating the distance d between the kth second locus point and the tangent line by adopting the following formula:
wherein the coordinates of the kth second track point are (x)k，yk)，k＝1,2,3......q。
In a second aspect, a high-precision automobile and automobile train steering test system is provided, which comprises:
the real-time calculation module is used for calculating the initial turning radius of the initial arc-shaped track; wherein the initial arc-shaped track is obtained by steering a running vehicle on a test site;
the judging module is used for judging whether the initial turning radius is within a preset target radius range or not; if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track through the real-time calculation module until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle;
the acquisition module is used for acquiring a first running track and a second running track of a first measuring point and a second measuring point on the vehicle in the process of stopping after the vehicle returns to a forward direction disk and travels a distance in a straight line from a driving position; the first measuring point and the second measuring point are respectively arranged at the outermost position and the outermost position of the vehicle; the driving-away position is a stopping position when the vehicle keeps the target corner to continue to steer until the vehicle stops steering and forms a target arc-shaped track;
a post-processing module for fitting the first travel trajectory to a tangent that passes through the drive-off location and is tangent to the target arc trajectory; and the maximum distance between the second driving track and the tangent is calculated and is used as the driving-off outward swinging value of the vehicle.
The beneficial effect that technical scheme that this application provided brought includes:
1. no site line drawing is needed, and the limitation of the site is removed.
2. When the vehicle can be quickly determined to run within the preset target radius range, the required steering wheel corner is avoided, the driver spends time finding the steering circle, the driving difficulty is greatly reduced, and the accuracy and the repeatability of the test are improved.
3. The turning radius of the vehicle can be displayed in the visual field range of the driver in real time, the driver can observe the vehicle conveniently, and the operation difficulty and the test risk are reduced.
4. The driver can drive away from the tangent line at any point of the steering circle, the situation that the driver is difficult to confirm the tangent point on the ground marking line when driving away from the steering circle along the tangent line and deviates from the ground, the previously drawn tangent line causes test failure is avoided, and the test efficiency and the reliability of data are greatly improved.
5. The system realizes real-time monitoring, whole-course track acquisition, rapid calculation and on-site test result acquisition, and solves the problems of difficult tracking of a driver, poor accuracy of the test result and difficult subsequent data processing.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a yaw rate test in the background art of the present application;
FIG. 2 is a flow chart of a high-precision automobile and automobile train steering test method provided by the embodiment of the application;
FIG. 3 is a schematic diagram of a high-precision vehicle steering tracking test system according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Example 1:
referring to fig. 2, embodiment 1 of the present application provides a high-precision automobile and automobile train steering test method, which includes the following steps:
s1: steering a running vehicle on a test field to obtain a section of initial arc-shaped track;
s2: calculating the initial turning radius of the initial arc-shaped track;
the embodiment of the application obtains the initial turning radius by fitting the initial arc-shaped track.
S3: if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle;
s4: keeping the target corner to continue steering to stop steering, simultaneously forming a target arc-shaped track, and taking a stop position as a driving-away position;
s5: returning to the positive direction disk, and stopping after linearly driving for a certain distance from the driving position;
s6: in the straight-line driving process, acquiring a first driving track and a second driving track of a first measuring point and a second measuring point on a vehicle; the first measuring point and the second measuring point are respectively arranged at the foremost and outmost positions and the rearmost and outmost positions of the vehicle;
s7: fitting the first driving track into a tangent line, wherein the tangent line passes through a driving-off position and is tangent to the target arc-shaped track;
s8: and calculating the maximum distance between the second running track and the tangent line, and taking the maximum distance as the driving-off outward swinging value of the vehicle.
The beneficial effects of the embodiment 1 of the application are as follows:
1. no site line drawing is needed, and the limitation of the site is removed.
2. When the vehicle can be quickly determined to run within the preset target radius range, the required steering wheel corner is avoided, the driver spends time finding the steering circle, the driving difficulty is greatly reduced, and the accuracy and the repeatability of the test are improved.
3. The turning radius of the vehicle can be displayed in the visual field range of the driver in real time, the driver can observe the vehicle conveniently, and the operation difficulty and the test risk are reduced.
4. The driver can drive away from the tangent line at any point of the steering circle, the situation that the driver is difficult to confirm the tangent point on the ground marking line when driving away from the steering circle along the tangent line and deviates from the ground, the previously drawn tangent line causes test failure is avoided, and the test efficiency and the reliability of data are greatly improved.
5. The system realizes real-time monitoring, whole-course track acquisition, rapid calculation and on-site test result acquisition, and solves the problems of difficult tracking of a driver, poor accuracy of the test result and difficult subsequent data processing.
Further, the specific steps of step S3 are as follows:
s30: taking the turning radius of the arc-shaped track of the vehicle running within a first preset time length as an instant radius;
s31: roughly adjusting the turning angle of the steering wheel by taking the instant radius as a reference;
s32: taking the turning radius of the arc-shaped track of the vehicle running within a second preset time length as a stable radius, wherein the second preset time length is longer than the first preset time length;
s33: finely adjusting the turning angle of the steering wheel by taking the stable radius as a reference;
s34: and taking the steering wheel corner as the target corner at the moment until the stable radius is within the preset target radius range.
Specifically, the method comprises the following steps: for example, the first preset time is 2s, the second preset time is 5s, the running track of the vehicle in 2s is obtained, a short arc is obtained, and the turning radius of the short arc is used as the instant radius; acquiring the running track of the vehicle in 5s to obtain a long arc, and taking the turning radius of the long arc as a stable radius
Since the fitting calculation must be calculated from a section of historical track points that the vehicle has recently traveled, a certain contradiction is created: the more the number of the selected recent historical track points is, the more accurate the calculated turning radius is, but the more delayed the calculated turning radius is, the driver cannot quickly find the specified radius; the smaller the number of the selected recent historical track points, the smaller the lag of the calculated turning radius, but the unstable calculated turning radius, the driver cannot quickly find the specified radius.
Therefore, the calculation results can be set to be two, namely, the instant radius calculated by selecting the short-time historical track points (the number of the corresponding track points is small), and the value is quick in response but large in fluctuation; the other method is to select the stable radius calculated by long-time historical track points (the number of the corresponding track points is large), and the value is high in accuracy, gentle in fluctuation, easy to maintain and slow in response.
The two calculation results are simultaneously displayed on the observation screen of the driver, so that the driver can quickly correct the steering wheel to be near the target radius according to the instant radius when driving the vehicle, and then finely adjust the steering wheel. Meanwhile, according to the stable radius, a driver can be well stabilized on the target radius, and the vehicle can be operated to stably run at the target radius.
Further, a recursive average filtering method is used to calculate the instantaneous radius and the stable radius.
The radius of the displayed steering circle is the average radius of the arc of the vehicle in running, but the data fluctuation is large due to the unstable state of the vehicle in running, so that the interference of factors such as vehicle vibration and the like on the data is reduced, the recursion average filtering is carried out on the turning radius calculated in real time, the accuracy of the data is ensured, and the data fluctuation is reduced.
Preferably, the step of calculating the instantaneous radius by using a recursive average filtering method specifically comprises the following steps:
s300: continuously acquiring s plane coordinates on an arc track of a vehicle running within a first preset time length, and taking the s plane coordinates as a first queue;
s301: the vehicle continues to run to obtain a new arc-shaped track, a new coordinate obtained on the new arc-shaped track is placed at the tail of the queue, and a coordinate of the head of the previous first queue is thrown away to serve as a new first queue;
s302: the turn radius of the new first queue is calculated and taken as the instant radius.
Specifically, for example, the first preset time period is 2s, the radius of the track running within 0-2s is taken as the instant radius, the running is continued, the radius of the track running within 0.1-2.1s is taken as the instant radius, and the like, and the instant radius is displayed in real time.
Preferably, the stable radius is calculated by a recursive average filtering method, which specifically comprises the following steps:
s320: continuously acquiring t plane coordinates on an arc-shaped track of the vehicle running within a second preset time length, and taking the t plane coordinates as a second queue; wherein t > s;
s321: the vehicle continues to run, a new arc-shaped track is obtained again, a new coordinate obtained on the new arc-shaped track is placed at the tail of the queue, and a coordinate of the head of the previous second queue is thrown away to serve as a new second queue;
s322: and calculating the turning radius of the new second queue, and taking the turning radius as a stable radius.
Specifically, for example, the first preset time period is 5s, the radius of the track traveled within 0 to 5s is taken as the stable radius, the vehicle continues to travel, the radius of the track traveled within 0.1 to 5.1s is taken as the stable radius, and so on, and the stable radius is displayed in real time.
Further, the step S2 of calculating the initial turning radius of the initial arc trajectory specifically includes the following steps:
s20: fitting the initial arc-shaped track to obtain a fitting circle; recording the radius of the fitting circle as R and the coordinates of the circle center as A and B;
s21: acquiring n plane coordinates of the first measuring point on the initial arc track, and recording the plane coordinate of the first measuring point acquired at the ith time as (x)i，yi) (ii) a Wherein, i is 1, 2.. n, n represents the number of acquisitions per cycle;
s22: calculating the distance d from the first measuring point acquired at the ith time to the center of the fitting circleiSquared difference σ with radius R of fitting circleiThe formula is as follows:
order:
then:
determining the parameters a, b, c such that the value of Q (a, b, c) is minimal, wherein:
s23: when the minimum value of Q (a, b, c) is found by finding the partial derivatives for a, b, c and setting the partial derivatives to 0, respectively:
simplifying the three formulas and solving a ternary linear equation set;
order:
D＝(n∑xiyi-∑xi∑yi)
then a, b, c are as follows:
s24: finally, parameters of the fitting circle are obtained:
let R be the initial turning radius.
Similarly, the instant radius and the stable radius are calculated in the above manner.
Furthermore, in step S22, acquiring n plane coordinates of the first measurement point on the initial arc trajectory, specifically including the following steps:
s220: installing a GPS on the first measuring point, and acquiring a first GPS coordinate of the first measuring point on the initial arc-shaped track;
s221: taking the GPS coordinate as an origin of a coordinate system of the test site, and calculating to obtain an X axis and a Y axis of the coordinate system according to an east axis and a north axis of the GPS coordinate system;
s222: and all the n GPS coordinates of the first measuring point on the initial arc-shaped track are converted into plane coordinates according to a coordinate system of the test field.
Converting all GPS coordinates into plane coordinates by adopting a coordinate projection conversion method, wherein the coordinate projection conversion method comprises the following steps:
x＝Northings*cosθ+Eastings*sinθ
y＝Northings*sinθ-Eastings*cosθ
wherein: r iseIs the radius of the earth, e is the eccentricity of the earth,
is latitude, λ is longitude, z is altitude, and θ is azimuth (in radians, rotated clockwise from north).
Inputting the initial Latitude phi and Longitude lambda of the point A as the origin of the coordinate system of the test site, substituting the real-time Latitude Latitude, Longitude Longitude and altitude z into the former two formulas to calculate the values of east axis Eastings and north axis Northings of the Longitude and Latitude coordinate system, and substituting Eastings and Northings into the latter two formulas to calculate the values of the X axis and Y axis directions of the coordinate system of the test site.
After the vehicle stably runs for a certain distance along the target radius, the driver quickly returns to the steering wheel, the vehicle drives away from the steering circle along the tangent line, and the tangent line of the steering circle is obtained by calculating the collected outermost point track (first running track) through fitting because the track of the outermost point is close to a straight line in the running process of the vehicle, but the track cannot be an ideal straight line due to vehicle vibration and other factors.
Fitting the first travel track to a tangent line, specifically comprising the steps of:
let the tangent equation be: y ═ ax + b
Obtaining the coordinates of m first track points on the first traveling track, and recording the plane coordinate of the jth first track point as (x)j，yj)，j＝1,2,3......m；
And calculating the sum of squares of the distance from the m first track points to the straight line y, wherein the sum is equal to ax and b, and is recorded as E (a and b), wherein:
E(a,b)＝∑(yj-axj-b)2
when E (a, b) is minimum, corresponding coefficients a and b are calculated, and the specific steps are as follows:
and respectively calculating the partial derivatives of a and b, and setting the partial derivative value to be 0, namely:
obtaining a system of linear equations of two in relation to a and b from the above formula, and solving the system of equations;
order:
E＝∑xj
F＝∑xjyj
G＝∑yj
convert the above system of linear equations into
a×D+b×E-F＝0
a×E+m×b-G＝0
The equation can be solved:
further, in step S8, the maximum distance between the second driving track and the tangent line is calculated and used as the driving-off yaw value of the vehicle, which specifically includes the following steps:
s80: obtaining coordinates of q second track points positioned on the outer side of the tangent line on a second running track;
wherein, the outer side of the tangent line refers to the side far away from the fitting circle.
S81: calculating the distance between all the second track points and the tangent line;
s82: and taking the maximum value of all the distances as the driving-away swing value of the vehicle.
Further, the distance d between the kth second locus point and the tangent line is calculated by the following formula:
wherein the coordinates of the kth second track point are (x)k，yk)，k＝1,2,3......q。
According to the embodiment 1 of the application, the vehicle turning radius and the vehicle track are calculated in real time by collecting high-precision GPS longitude and latitude positioning information, interference caused by factors such as vehicle vibration is reduced by adopting a recursion average filtering mode, the turning radii with different arc lengths are calculated by combining collection, and are displayed for a driver, so that the problems of data hysteresis and how to quickly and accurately determine the turning radius are solved, the test accuracy is greatly improved, and the working efficiency is improved.
In addition, through monitoring the steering wheel corner, the mode that the sudden change moment of the steering wheel corner is used as a tangent point when the tangent line of the vehicle is driven away from a steering circle and the tangent line is calculated by fitting the track point of the foremost outermost measuring point is adopted, the problem that the tangent point and the tangent line driving track are difficult to determine in the actual test driving process is solved, and the driving difficulty is greatly reduced.
And finally, after a tangent line is determined by fitting the tangent line track of the foremost outermost point, generating the GPS positioning data of the rearmost outermost point collected in real time into the track of the rearmost outermost point, and quickly calculating the maximum distance from the track point to the tangent line formed by the foremost outermost point, thereby solving the problems that the maximum distance point is difficult to find, the repeatability of the test of the distance from the outer swing value is poor, the accuracy is low, and the reliability of the test result is greatly improved.
Example 2:
referring to fig. 3, embodiment 2 of the present application provides a high-precision vehicle steering tracking test system, which includes a GPS positioning system, a portable base station, a data acquisition device, a display, a force-measuring steering wheel, and a steering test software system provided in the data acquisition device, where the steering test software system includes a real-time calculation module, a determination module, an acquisition module, and a post-processing module.
The real-time calculation module is used for calculating the initial turning radius of the initial arc-shaped track; wherein the initial arc-shaped track is obtained by steering a running vehicle on a test site;
the judging module is used for judging whether the initial turning radius is within a preset target radius range; if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track through a real-time calculation module until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle;
the acquisition module is connected with the GPS and used for acquiring coordinates of a first measuring point and a second measuring point on the vehicle acquired by the GPS in the process of stopping after the vehicle travels straight for a distance from a driving position after returning to a steering wheel, and generating a first traveling track and a second traveling track according to the coordinates of the first measuring point and the second measuring point; the first measuring point and the second measuring point are respectively arranged at the foremost outermost position and the rearmost outermost position of the vehicle; the driving-away position is a stopping position when the vehicle keeps a target corner to continue steering and drive to stop steering and forms a target arc-shaped track;
the post-processing module is used for fitting the first driving track into a tangent line, and the tangent line passes through the driving-off position and is tangent to the target arc-shaped track; and the maximum distance between the second running track and the tangent line is calculated and is used as the driving-off swing value of the vehicle.
The specific installation mode of the high-precision vehicle steering tracking test system is as follows:
during testing, a GPS antenna is respectively arranged at a first measuring point and a second measuring point of a vehicle, tracks of the first measuring point and the second measuring point are collected, a portable base station is erected on a test site, the GPS positioning precision is improved to be less than or equal to 2cm, a force measuring steering wheel is fixed on the vehicle steering wheel, a display is fixed in the visual field range of a driver, a data acquisition device provided with a steering test software system is fixed in a cab, and the force measuring steering wheel, the GPS antenna and the data acquisition device are connected by using a data line.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A high-precision automobile and automobile train steering test method is characterized by comprising the following steps:
steering a running vehicle on a test field to obtain a section of initial arc-shaped track;
calculating the initial turning radius of the initial arc-shaped track;
if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle;
keeping the target corner to continue steering to stop steering, simultaneously forming a target arc-shaped track, and taking a stop position as a driving-away position;
the steering wheel returns, and stops after the vehicle travels a certain distance in a straight line from the driving position;
in the straight-line driving process, acquiring a first driving track and a second driving track of a first measuring point and a second measuring point on a vehicle; the first measuring point and the second measuring point are respectively arranged at the foremost and outmost positions and the rearmost and outmost positions of the vehicle;
fitting the first travel track into a tangent line, wherein the tangent line passes through the travel-away position and is tangent to the target arc-shaped track;
and calculating the maximum distance between the second running track and the tangent line, and taking the maximum distance as a running-away outer swing value of the vehicle.
2. The high-precision automobile and automobile train steering test method according to claim 1, characterized in that:
taking the turning radius of the arc-shaped track of the vehicle running within a first preset time length as an instant radius;
roughly adjusting the turning angle of the steering wheel by taking the instant radius as a reference;
taking the turning radius of an arc-shaped track of a vehicle running within a second preset time length as a stable radius, wherein the second preset time length is longer than the first preset time length;
finely adjusting the turning angle of the steering wheel by taking the stable radius as a reference;
and taking the steering wheel corner as a target corner at the moment until the stable radius is within the preset target radius range.
3. The method as claimed in claim 2, wherein the instantaneous radius and the stable radius are calculated by recursive average filtering.
4. The method for testing the steering of high-precision automobiles and trains according to claim 3, wherein the step of calculating the instant radius by a recursive average filtering method comprises the following steps:
continuously acquiring s plane coordinates on an arc track of a vehicle running within a first preset time length, and taking the s plane coordinates as a first queue;
the vehicle continues to run to obtain a new arc-shaped track, a new coordinate obtained on the new arc-shaped track is placed at the tail of the queue, and a coordinate of the head of the previous first queue is thrown away to serve as a new first queue;
the turn radius of the new first queue is calculated and taken as the instant radius.
5. The method for testing the steering of the high-precision automobile and the automobile train as claimed in claim 4, wherein the stable radius is calculated by a recursive average filtering method, which comprises the following steps:
continuously acquiring t plane coordinates on an arc-shaped track of the vehicle running within a second preset time length, and taking the t plane coordinates as a second queue; wherein t > s;
the vehicle continues to run, a new arc-shaped track is obtained again, a new coordinate obtained on the new arc-shaped track is placed at the tail of the queue, and a coordinate of the head of the previous second queue is thrown away to serve as a new second queue;
and calculating the turning radius of the new second queue, and taking the turning radius as a stable radius.
6. The method for testing the steering of automobiles and trains with high precision as claimed in claim 1, wherein the step of calculating the initial turning radius of the initial arc-shaped track comprises the following steps:
fitting the initial arc-shaped track to obtain a fitting circle; recording the radius of the fitting circle as R and the coordinates of the circle center as (A, B);
acquiring n plane coordinates of the first measuring point on the initial arc-shaped track, and recording the plane coordinate of the first measuring point acquired at the ith time as (x)i，yi) (ii) a Wherein, i is 1, 2.. n, n represents the number of acquisitions per cycle;
calculating the distance d from the first measuring point acquired at the ith time to the center of the fitting circleiSquared difference σ with radius R of the fitted circleiThe formula is as follows:
order:
then:
determining the parameters a, b, c such that the value of Q (a, b, c) is minimal, wherein:
when the minimum value of Q (a, b, c) is found by finding the partial derivatives for a, b, c and setting the partial derivatives to 0, respectively:
simplifying the three formulas and solving a ternary linear equation set;
order:
D＝(n∑xiyi-∑xi∑yi)
then a, b, c are as follows:
finally, obtaining parameters of the fitting circle:
and taking R as the initial turning radius.
7. The high-precision automobile and automobile train steering test method according to claim 6, wherein n plane coordinates of the first measuring point on the initial arc-shaped track are collected, and the method specifically comprises the following steps:
installing a GPS on the first measuring point to obtain a first GPS coordinate of the first measuring point on the initial arc-shaped track;
taking the GPS coordinate as an origin of a coordinate system of the test site, and calculating to obtain an X axis and a Y axis of the coordinate system according to an east axis and a north axis of the GPS coordinate system;
and converting the n GPS coordinates of the first measuring point on the initial arc-shaped track into plane coordinates according to a coordinate system of a test field.
8. The method for testing the steering of automobiles and trains with high precision according to claim 1, wherein the fitting of the first driving trajectory to a tangent line specifically comprises the following steps:
let the tangent equation be: y ═ ax + b
Obtaining the coordinates of m first track points on the first traveling track, and recording the plane coordinate of the jth first track point as (x)j，yj)，j＝1,2,3......m；
And calculating the sum of squares of the distance from the m first track points to the straight line y, wherein the sum is equal to ax and b, and is recorded as E (a and b), wherein:
E(a,b)＝∑(yj-axj-b)2
when E (a, b) is minimum, corresponding coefficients a and b are calculated, and the specific steps are as follows:
and respectively calculating the partial derivatives of a and b, and setting the partial derivative value to be 0, namely:
obtaining a system of linear equations of two in relation to a and b from the above formula, and solving the system of equations;
order:
E＝∑xj
F＝∑xjyj
G＝∑yj
convert the above system of linear equations into
a×D+b×E-F＝0
a×E+m×b-G＝0
The equation can be solved:
9. the method for testing the steering of the high-precision automobile and the automobile train as claimed in claim 8, wherein the maximum distance between the second driving track and the tangent is calculated and used as the driving-away swing value of the vehicle, and the method comprises the following steps:
obtaining coordinates of q second track points positioned on the outer side of the tangent line on the second running track;
calculating the distance between all the second track points and the tangent line;
taking the maximum value of all the distances as a driving-away outer swing value of the vehicle;
calculating the distance d between the kth second locus point and the tangent line by adopting the following formula:
wherein the coordinates of the kth second track point are (x)k，yk)，k＝1,2,3......q。
10. The utility model provides a high accuracy car and motor train turns to test system which characterized in that, it includes:
the real-time calculation module is used for calculating the initial turning radius of the initial arc-shaped track; wherein the initial arc-shaped track is obtained by steering a running vehicle on a test site;
the judging module is used for judging whether the initial turning radius is within a preset target radius range or not; if the initial turning radius is not within the preset target radius range, adjusting the turning angle of the steering wheel, continuing steering driving to obtain a new arc-shaped track, recalculating the turning radius of the new arc-shaped track through the real-time calculation module until the turning radius is within the preset target radius range, and taking the turning angle of the steering wheel at the moment as a target turning angle;
the acquisition module is used for acquiring a first running track and a second running track of a first measuring point and a second measuring point on the vehicle in the process of stopping after the vehicle returns to a forward direction disk and travels a distance in a straight line from a driving position; the first measuring point and the second measuring point are respectively arranged at the outermost position and the outermost position of the vehicle; the driving-away position is a stopping position when the vehicle keeps the target corner to continue to steer until the vehicle stops steering and forms a target arc-shaped track;
a post-processing module for fitting the first travel trajectory to a tangent that passes through the drive-off location and is tangent to the target arc trajectory; and the maximum distance between the second driving track and the tangent is calculated and is used as the driving-off outward swinging value of the vehicle.
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