CN111323168B - Method for measuring and calculating height of mass center of automobile - Google Patents

Method for measuring and calculating height of mass center of automobile Download PDF

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CN111323168B
CN111323168B CN202010301307.0A CN202010301307A CN111323168B CN 111323168 B CN111323168 B CN 111323168B CN 202010301307 A CN202010301307 A CN 202010301307A CN 111323168 B CN111323168 B CN 111323168B
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axle
automobile
center
distance
wheel
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CN111323168A (en
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谢卫兵
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Faw Hongta Yunnan Automobile Co ltd
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Faw Hongta Yunnan Automobile Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M1/00—Testing static or dynamic balance of machines or structures
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    • G01M1/122—Determining position of centre of gravity

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Abstract

The invention discloses a method for measuring and calculating the height of the mass center of an automobile, which comprises the following steps of when the automobile is in a static state,measuring front axle total axle load Ff0Rear axle main axle load Fr0The distances Xf0 and Xr0 from the axle center to the XOY plane and the automobile wheel base L, the distances Xf and Xr from the acceleration a and the axle center to the XOY plane are measured in the automobile braking state, and the height of the mass center of the automobile is calculated by measuring the change of the relative position of the automobile axle center and the automobile and the acceleration value. The invention only needs to collect the change of the relative position of the automobile axle center and the automobile and the acceleration value, does not need to be carried out on a bench in a laboratory, and is not limited by large overall size, more axles, heavy weight, space and weight.

Description

Method for measuring and calculating height of mass center of automobile
Technical Field
The invention belongs to the technical field of vehicle measurement, and particularly relates to a method for measuring and calculating the height of the mass center of an automobile.
Background
The position of the center of mass of the vehicle is divided into a horizontal position and a vertical position, and the vertical position is called the height of the center of mass. The height of the mass center of the automobile is an important parameter in the power control of the automobile, and has very important effects on the roll stability and the steering stability of the automobile. Particularly, vehicles with higher mass centers, such as tank cars, pump trucks, SUVs and the like, are extremely easy to turn over under extreme working conditions, and the damage degree of the rollover accident is usually extremely large. Modern vehicles equipped with active roll control systems often require accurate measurement of the height of the center of mass, which is of great application significance to the accurate measurement of the height of the center of mass of an automobile, since the measurement of the height of the center of mass is one of the most important but least easily measurable parameters. The traditional method for measuring the height of the mass center of the automobile needs to be carried out on a rack in a laboratory, but the overall dimension of many automobiles is large, the number of shafts is large, the weight is large, the height of the mass center of the automobile cannot be calculated due to the fact that the measurement of space and weight on the rack is limited, the height of one mass center is estimated by experience in most cases, and therefore the method is not beneficial to measurement of overload of the automobile, and meanwhile the measuring method has large potential safety hazards. Therefore, it is objectively needed to develop a method for measuring and calculating the height of the mass center of an automobile, which has the advantages of simple measuring method, universal measuring equipment, safe measuring process and accurate measuring result.
Disclosure of Invention
In order to solve the problems in the background art, the invention aims to provide a method for measuring and calculating the height of the mass center of an automobile, which has the advantages of simple measuring method, universal measuring equipment, safe measuring process and accurate measuring result.
The invention adopts the technical scheme that the method for measuring and calculating the height of the mass center of the automobile comprises the following steps:
the method comprises the following steps: selecting a straight and long enough road surface as a test road surface for automobile driving, wherein the adhesion coefficient of the test road surface is required to be more than or equal to 0.6, installing distance sensors on a front shaft and a rear shaft of an automobile, installing an acceleration sensor in the driving direction of the automobile, installing a display in a cab of the automobile, and the display can display the measurement values of the acceleration sensor and the distance sensor;
step two, when the automobile is in a static state on a test road surface:
firstly, the land scale is used for measuring the total axle load F of the front axle of the automobilef0And the total axle load F of the rear axler0；
Secondly, in a whole automobile coordinate system X, Y, Z, measuring the distance Xf0 from the axle center of a front axle wheel of the automobile to an XOY plane by using a distance sensor, and measuring the distance Xr0 from the axle center of a rear axle wheel of the automobile to the XOY plane by using the distance sensor;
determining the wheel base L of the automobile;
fourthly, determining the relation between the relative position of the axle center of the automobile road and the axle load: the distance Xf0 from the axle center of the front axle wheel of the automobile to the XOY surface, the distance Xr0 from the axle center of the rear axle wheel of the automobile to the XOY surface, and the total axle load F of the front axle of the automobile when the automobile is in a static state according to the automobile design theoryf0As a function of Xf0 is Ff0Funf (xf0), total axle load F of rear axle of automobiler0As a function of Xr0 is Fr0＝funr(Xr0)；
Step three: the method comprises the steps that a vehicle is enabled to run on a test road surface in an accelerated mode, when the vehicle accelerates to a vehicle speed V0, data of acceleration a are recorded, then a brake plate is stepped on, the change of deceleration acceleration a is observed, when the accelerated acceleration a reaches a designated value a0, the brake plate of the vehicle is kept still, the vehicle is enabled to run in a uniform deceleration state until the vehicle stops, in the process that the vehicle keeps the uniform deceleration state, the distance Xf from the wheel axle center of a front axle of the vehicle to an XOY surface and the distance Xr from the wheel axle center of a rear axle of the vehicle to the XOY surface are measured by a distance sensor;
step four: in the case of automobile braking, according to the theory of automobile design, it can be known that:
Figure GDA0003200357380000021
Figure GDA0003200357380000022
wherein, FzfIs the sum of the axle load of the front axle under braking, FzrThe sum of the axle loads of all rear axles under braking, G is the weight of the automobile, h is the height of the mass center, a is the acceleration, L is the wheelbase, G is the acceleration of gravity, Ff0、Fr0Respectively the front axle total axle load and the rear axle total axle load of the automobile under the static state;
step five: the distance Xf from the wheel center of the front axle of the automobile to the XOY surface and the distance Xr from the wheel center of the rear axle of the automobile to the XOY surface under the condition of automobile braking are determined according to the automobile design theoryzfAs a function of Xf is FzfFunf (xf), automobile rear axle load FzrAs a function of Xr is Fzr＝funr(Xr)；
Step six: the formulas in the second step, the fourth step and the fifth step are combined to obtain
Figure GDA0003200357380000023
Figure GDA0003200357380000024
The height h of the mass center can be calculated to be
Figure GDA0003200357380000025
Or
Figure GDA0003200357380000026
The centroid height h can be calculated by substituting the values of funf (Xf), funf (Xf0), funr (Xr0), funr (Xr), L, G, G, a.
Further, in step one: when the distance sensors are arranged on the front axle and the rear axle of the automobile, the distance sensors are respectively arranged on the left side and the right side of the front axle of the automobile of the single front axle; the double-front-axle automobile is characterized in that a distance sensor is respectively arranged on the left side and the right side of a first front axle and a second front axle, a distance sensor is respectively arranged on the left side and the right side of a rear axle of a single-rear-axle automobile, and a distance sensor is not arranged on the rear axle of a multi-rear-axle automobile.
Furthermore, in the step two, when the total axle load of the front axle is measured, the axle load of the front axle measured by the single front axle automobile is Fzf1I.e. the total axle load F of the front axle of the vehiclef0＝FZf1(ii) a For a dual front axle vehicle, the first front axle F is measured separatelyzf1And second front axle load Fzf2I.e. the total axle load F of the front axle of the vehiclef0＝FZf1+FZf2；
When measuring the total axle load of the rear axle, firstly measuring the axle load F of each axle of the rear axlezr1、Fzr2……FzrnAnd n is the rear axle sequence number, the total axle load F of the rear axle of the automobiler0＝FZr1+FZr2+……+FZrn。
Further, in the second step, when the distance Xf0 from the axle center of the front axle wheel to the XOY plane is measured:
a: for a single front axle automobile, measuring the left axle center Xf1l0 of the front axle wheel of the automobile and the right axle center Xf1r0 of the front axle wheel of the automobile, wherein the distance Xf0 from the axle center of the front axle wheel of the automobile to an XOY plane is Xf0 ═ Xf1l0+ Xf1r 0)/2;
for a double-front-axle automobile, firstly measuring the distances from the left axle center of a first front-axle wheel, the right axle center of the first front-axle wheel, the left axle center of a second front-axle wheel and the right axle center of the second front-axle wheel to an XOY plane as Xf1l0, Xf1r0, Xf2l0 and Xf2r0 respectively, and then the distance Xf0 from the axle center of the front-axle wheel to the XOY plane is Xf0 ═ (Xf1l0+ Xf1r0+ Xf2l0+ Xf2r 0)/4;
when the distance Xf0 from the axle center of the rear axle of the automobile to the XOY plane is measured:
c: for a single-rear-axle automobile, firstly measuring a rear wheel left-side axle center Xrl0 and a rear wheel right-side axle center Xrr0 of the single-rear-axle automobile, wherein the distance Xr0 from the automobile rear axle to an XOY plane is Xr0 ═ Xrl0+ Xrr 0)/2;
d: for a multi-rear-axle automobile, the distance from the left and right side axle centers of each rear axle gear to the XOY plane is not required to be measured, and the distance Xr0 from the axle centers of the multi-rear-axle automobile to the XOY plane is the distance Xf0 from the axle centers of the front axle wheels of the double front axles to the XOY plane, namely Xr0 is Xf 0.
Furthermore, in the third step, the wheel base L of the automobile is determined
a: for a single front axle and a single rear axle automobile, the automobile wheelbase L is the distance from the axle center of the front axle to the axle center of the rear axle;
b: for a double-front-axle and single-rear-axle automobile, the automobile wheelbase L is the distance from the midpoint of the axle centers of the two front axles to the axle center of the rear axle;
c: for double-front-axle and multi-rear-axle automobiles, when the single rear axle load of the automobile is easy to measure, the wheelbase of the automobile is determined according to the wheel base
Figure GDA0003200357380000031
Performing an equivalent calculation wherein Fzr1、Fzr2……FzrnFor the axle load of each axle of the rear axle, L1 … … Ln is the distance between the midpoint of the axle centers of the two front axles and the axle center of the nth axle of the rear axle;
d: for a double-front-axle and multi-rear-axle automobile, when the single rear axle load of the automobile can not be measured, the axle distance L of the automobile is determined according to the following method:
d.1: if the rear axles of the vehicle are uniformly distributed, the wheel base of the vehicle is pressed
Figure GDA0003200357380000041
Calculating, wherein L1 … … Ln is the distance between the middle point of the axle centers of the two front axles and the nth axle center of the rear axle;
d.2: if the axle center distance of two adjacent rear axles of the automobile is less than or equal to 1.5 times of the tire radius, the two rear axles can be equivalent to one axle, the axle center is the center of the axle centers of the two rear axles, the axle load is the sum of the axle loads of the two axles, and the axle distance L is calculated by using the method c;
d.3: if the number of the rear shafts is more and a rear shaft group exists, the rear shaft group is formed by a plurality of shafts (the number of the shafts is more than or equal to 3), the distances between the axes of two continuous adjacent rear shafts are equal, the shaft group can be equivalent to one shaft, the axis is the center of the axis of the head rear shaft and the end rear shaft, the shaft load is the sum of the shaft loads of all the shafts of the shaft group, and the shaft distance L is calculated by using the method c;
when the conditions in d.1, d.2 and d.3 are satisfied simultaneously, the method of d.1 is preferably selected for calculation.
Further, in the seventh step, when the height h of the mass center of the automobile is calculated, for the automobile with a single front axle and the automobile with a single rear axle, the values h are calculated by respectively using the formula (1) and the formula (2) to reduce errors, and then the average value of the values h is taken; for the automobile with double front shafts and single rear shafts and the automobile with double front shafts and multiple rear shafts, the height h of the mass center of the automobile is calculated by adopting the formula (1).
Furthermore, in the step one, the precision of the accelerator sensor is required to be greater than or equal to 0.001g, and the precision of the distance sensor is required to be greater than or equal to 0.001 m.
Further, in the third step, when the measured acceleration value a0 and the distance value from the axle center of the automobile wheel to the XOY surface are kept unchanged for more than 2 seconds or within 5% in a single test in the process of keeping the automobile in the uniform deceleration state, the test and related data are valid, otherwise, the test is invalid, and the test needs to be performed again.
According to the invention, the height of the mass center of the automobile is calculated by measuring the change of the relative position of the automobile axis and the automobile and the acceleration value according to the change of the relative position of the automobile tire and the automobile caused by the axle load transfer caused by the acceleration of the automobile in the braking process of the automobile. The invention only needs to collect the change and the acceleration value of the relative position of the automobile axle center and the automobile, does not need to be carried out on a bench in a laboratory, and is not limited by large overall size, more axles, heavy weight, space and weight.
Drawings
FIG. 1 is a schematic illustration of an automobile tested at rest;
FIG. 2 is a diagram illustrating the measurement of the distance from the axle center of the wheel to the XOY plane when the vehicle is at rest;
fig. 3 shows the distance from the axle center of the wheel to the XOY plane when the vehicle is in a braking state.
Detailed Description
The invention is further illustrated by the following description of embodiments and the accompanying drawings, without in any way limiting the invention, and any alterations or substitutions made on the basis of the teachings of the invention shall fall within the scope of protection of the invention.
As shown in FIGS. 1 to 3: the invention relates to a method for measuring and calculating the height of the mass center of an automobile, which is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: selecting a straight and long enough road surface as a test road surface for automobile running, wherein the adhesion coefficient of the test road surface is required to be more than or equal to 0.6, in order to prevent the automobile from slipping when running on the running road surface, distance sensors are arranged on a front shaft and a rear shaft of the automobile, an acceleration sensor is arranged in the running direction of the automobile, a display is arranged in a cab of the automobile, and the display can display the measurement values of the acceleration sensor and the distance sensor; when the distance sensors are arranged on the front axle and the rear axle of the automobile, the distance sensors are respectively arranged on the left side and the right side of the front axle of the automobile of the single front axle; the method comprises the following steps that a double-front-axle automobile is provided with a distance sensor on the left side and the right side of a first front axle and a second front axle respectively, a single-rear-axle automobile is provided with a distance sensor on the left side and the right side of a rear axle respectively, and a multi-rear-axle automobile is not provided with a distance sensor on a rear axle, wherein the data acquisition period of an accelerator sensor and the distance sensor needs to be less than or equal to 0.1 second, namely 10 times of acquisition per second or more, the precision of the accelerator sensor needs to be more than or equal to 0.001g, and the precision of the distance sensor needs to be more than or equal to 0.001 m;
step two, when the automobile is in a static state on a test road surface:
firstly, the land scale is used for measuring the total axle load F of the front axle of the automobilef0And the total axle load F of the rear axler0Measuring the total axle load of the front axleIn the meantime, for a single front axle automobile, the single front axle automobile measures the front axle load as Fzf1I.e. the total axle load F of the front axle of the vehiclef0＝FZf1(ii) a For a dual front axle vehicle, the first front axle F is measured separatelyzf1And second front axle load Fzf2I.e. the total axle load F of the front axle of the vehiclef0＝FZf1+FZf2；
When measuring the total axle load of the rear axle, firstly measuring the axle load F of each axle of the rear axlezr1、Fzr2……FzrnAnd n is the rear axle sequence number, the total axle load F of the rear axle of the automobiler0＝FZr1+FZr2+……+FZrn；
Secondly, in the whole vehicle coordinate system X, Y, Z, a distance sensor is used for measuring the distance Xf0 from the axle center of the front axle wheel of the vehicle to the XOY plane, a distance sensor is used for measuring the distance Xr0 from the axle center of the rear axle wheel of the vehicle to the XOY plane,
when the distance Xf0 from the axle center of the front axle wheel of the automobile to the XOY plane is measured:
a: for a single front axle automobile, measuring the left axle center Xf1l0 of the front axle wheel of the automobile and the right axle center Xf1r0 of the front axle wheel of the automobile, wherein the distance Xf0 from the axle center of the front axle wheel of the automobile to an XOY plane is Xf0 ═ Xf1l0+ Xf1r 0)/2;
for a double-front-axle automobile, firstly measuring the distances from the left axle center of a first front-axle wheel, the right axle center of the first front-axle wheel, the left axle center of a second front-axle wheel and the right axle center of the second front-axle wheel to an XOY plane as Xf1l0, Xf1r0, Xf2l0 and Xf2r0 respectively, and then the distance Xf0 from the axle center of the front-axle wheel to the XOY plane is Xf0 ═ (Xf1l0+ Xf1r0+ Xf2l0+ Xf2r 0)/4;
when the distance Xf0 from the axle center of the rear axle of the automobile to the XOY plane is measured:
c: for a single-rear-axle automobile, firstly measuring a rear wheel left-side axle center Xrl0 and a rear wheel right-side axle center Xrr0 of the single-rear-axle automobile, wherein the distance Xr0 from the automobile rear axle to an XOY plane is Xr0 ═ Xrl0+ Xrr 0)/2;
d: for a multi-rear-axle automobile, the distance from the axle center of the left side and the right side of each rear axle gear to the XOY plane is not required to be measured, the distance Xr0 from the axle center of the multi-rear-axle automobile to the XOY plane is the distance Xf0 from the axle center of the front axle wheel of the double front axles to the XOY plane, namely Xr0 is Xf 0;
determining the wheel base L of the automobile:
a: for a single front axle and a single rear axle automobile, the automobile wheelbase L is the distance from the axle center of the front axle to the axle center of the rear axle;
b: for a double-front-axle and single-rear-axle automobile, the automobile wheelbase L is the distance from the midpoint of the axle centers of the two front axles to the axle center of the rear axle;
c: for double-front-axle and multi-rear-axle automobiles, when the single rear axle load of the automobile is easy to measure, the wheelbase of the automobile is determined according to the wheel base
Figure GDA0003200357380000061
Performing an equivalent calculation wherein Fzr1、Fzr2……FzrnFor the axle load of each axle of the rear axle, L1 … … Ln is the distance between the midpoint of the axle centers of the two front axles and the axle center of the nth axle of the rear axle;
d: for a double-front-axle and multi-rear-axle automobile, when the single rear axle load of the automobile can not be measured, the axle distance L of the automobile is determined according to the following method:
d.1: if the rear axles of the vehicle are uniformly distributed, the wheel base of the vehicle is pressed
Figure GDA0003200357380000062
Calculating, wherein L1 … … Ln is the distance between the middle point of the axle centers of the two front axles and the nth axle center of the rear axle;
d.2: if the axle center distance of two adjacent rear axles of the automobile is less than or equal to 1.5 times of the tire radius, the two rear axles can be equivalent to one axle, the axle center is the center of the axle centers of the two rear axles, the axle load is the sum of the axle loads of the two axles, and the axle distance L is calculated by using the method c;
d.3: if the number of the rear shafts is more and a rear shaft group exists, the rear shaft group is formed by a plurality of shafts (the number of the shafts is more than or equal to 3), the distances between the axes of two continuous adjacent rear shafts are equal, the shaft group can be equivalent to one shaft, the axis is the center of the axis of the head rear shaft and the end rear shaft, the shaft load is the sum of the shaft loads of all the shafts of the shaft group, and the shaft distance L is calculated by using the method c;
when the conditions in d.1, d.2 and d.3 are satisfied simultaneously, the method of d.1 is preferably selected for calculation;
fourthly, determining the relation between the relative position of the axle center of the automobile road and the axle load: the distance Xf0 from the axle center of the front axle wheel of the automobile to the XOY surface, the distance Xr0 from the axle center of the rear axle wheel of the automobile to the XOY surface, and the total axle load F of the front axle of the automobile when the automobile is in a static state according to the automobile design theoryf0As a function of Xf0 is Ff0Funf (xf0), total axle load F of rear axle of automobiler0As a function of Xr0 is Fr0＝funr(Xr0)；
Step three: the method comprises the steps of enabling a vehicle to run on a test road surface in an accelerated mode, recording data of acceleration a when the vehicle accelerates to a vehicle speed V0, then stepping on a brake plate, observing change of deceleration acceleration a, keeping the brake plate of the vehicle still when the accelerated acceleration a reaches a designated value a0, enabling the vehicle to run in a uniformly decelerated mode until the vehicle stops, using a distance sensor to measure a distance Xf from a wheel axle center of a front axle of the vehicle to an XOY surface and a distance Xr from a wheel axle center of a rear axle of the vehicle to the XOY surface in the process that the vehicle keeps the uniformly decelerated mode, enabling a test and related data to be valid when a measured value a0 and a distance value from the wheel axle center of the vehicle to the XOY surface are kept unchanged for more than 2 seconds or change within 5% in a single test, otherwise enabling the test to be invalid, needing to conduct the test again, considering safety and not enabling the vehicle to decelerate rapidly in the test process, while avoiding wheel locking and affecting the measurement result, preferably, the acceleration a0 is less than or equal to 0.4g, and when a0 is 0.1g, 0.2g, 0.3g and 0.4g, the corresponding V0 can be selected by reference when V0 is 30km/h, 50km/h, 70km/h and 90km/h and other a0 values are recommended;
step four: in the case of automobile braking, according to the theory of automobile design, it can be known that:
Figure GDA0003200357380000071
Figure GDA0003200357380000072
wherein, FzfIs the sum of the axle load of the front axle under braking, FzrIs the sum of the axle loads of all rear axles under braking,g is the weight of the automobile, h is the height of the center of mass, a is the acceleration, L is the wheelbase, G is the acceleration of gravity, Ff0、Fr0Respectively the front axle total axle load and the rear axle total axle load of the automobile under the static state;
step five: the distance Xf from the wheel center of the front axle of the automobile to the XOY surface and the distance Xr from the wheel center of the rear axle of the automobile to the XOY surface under the condition of automobile braking are determined according to the automobile design theoryzfAs a function of Xf is FzfFunf (xf), automobile rear axle load FzrAs a function of Xr is Fzr＝funr(Xr)；
Step six: the formulas in the second step, the fourth step and the fifth step are combined to obtain
Figure GDA0003200357380000073
Figure GDA0003200357380000074
The height h of the mass center can be calculated to be
Figure GDA0003200357380000075
Or
Figure GDA0003200357380000076
Calculating the height h of the mass center by substituting the values of funf (Xf), funf (Xf0), funr (Xr0), funr (Xr), L, G, G and a, and calculating the height h of the mass center of the automobile by respectively calculating the values of h by using the formula (1) and the formula (2) for reducing errors of the automobile with a single front axle and a single rear axle and then averaging the values; for the automobile with double front shafts and single rear shafts and the automobile with double front shafts and multiple rear shafts, the height h of the mass center of the automobile is calculated by adopting the formula (1).

Claims (8)

1. A method for measuring and calculating the height of the mass center of an automobile is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: selecting a straight and long enough road surface as a test road surface for automobile driving, wherein the adhesion coefficient of the test road surface is required to be more than or equal to 0.6, installing distance sensors on a front shaft and a rear shaft of an automobile, installing an acceleration sensor in the driving direction of the automobile, installing a display in a cab of the automobile, and the display can display the measurement values of the acceleration sensor and the distance sensor;
step two, when the automobile is in a static state on a test road surface:
firstly, the land scale is used for measuring the total axle load F of the front axle of the automobilef0And the total axle load F of the rear axler0；
Secondly, in a whole automobile coordinate system X, Y, Z, measuring the distance Xf0 from the axle center of a front axle wheel of the automobile to an XOY plane by using a distance sensor, and measuring the distance Xr0 from the axle center of a rear axle wheel of the automobile to the XOY plane by using the distance sensor;
determining the wheel base L of the automobile;
fourthly, determining the relation between the relative position of the axle center of the automobile road and the axle load: the distance Xf0 from the axle center of the front axle wheel of the automobile to the XOY surface, the distance Xr0 from the axle center of the rear axle wheel of the automobile to the XOY surface, and the total axle load F of the front axle of the automobile when the automobile is in a static state according to the automobile design theoryf0As a function of Xf0 is Ff0Funf (xf0), total axle load F of rear axle of automobiler0As a function of Xr0 is Fr0＝funr(Xr0)；
Step three: the method comprises the steps that a vehicle is enabled to run on a test road surface in an accelerated mode, when the vehicle accelerates to a vehicle speed V0, data of acceleration a are recorded, then a brake plate is stepped on, the change of deceleration acceleration a is observed, when the accelerated acceleration a reaches a designated value a0, the brake plate of the vehicle is kept still, the vehicle is enabled to run in a uniform deceleration state until the vehicle stops, in the process that the vehicle keeps the uniform deceleration state, the distance Xf from the wheel axle center of a front axle of the vehicle to an XOY surface and the distance Xr from the wheel axle center of a rear axle of the vehicle to the XOY surface are measured by a distance sensor;
step four: in the case of automobile braking, according to the theory of automobile design, it can be known that:
Figure FDA0003212690460000011
Figure FDA0003212690460000012
wherein, FzfIs the sum of the axle load of the front axle under braking, FzrThe sum of the axle loads of all rear axles under braking, G is the weight of the automobile, h is the height of the mass center, a is the acceleration, L is the wheelbase, G is the acceleration of gravity, Ff0、Fr0Respectively the front axle total axle load and the rear axle total axle load of the automobile under the static state;
step five: the distance Xf from the wheel center of the front axle of the automobile to the XOY surface and the distance Xr from the wheel center of the rear axle of the automobile to the XOY surface under the condition of automobile braking are determined according to the automobile design theoryzfAs a function of Xf is FzfFunf (xf), automobile rear axle load FzrAs a function of Xr is Fzr＝funr(Xr)；
Step six: the formulas in the second step, the fourth step and the fifth step are combined to obtain
Figure FDA0003212690460000021
Figure FDA0003212690460000022
The height h of the mass center can be calculated to be
Figure FDA0003212690460000023
Or
Figure FDA0003212690460000024
The centroid height h can be calculated by substituting the values of funf (Xf), funf (Xf0), funr (Xr0), funr (Xr), L, G, G, a.
2. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the first step: when the distance sensors are arranged on the front axle and the rear axle of the automobile, the distance sensors are respectively arranged on the left side and the right side of the front axle of the automobile of the single front axle; the double-front-axle automobile is characterized in that a distance sensor is respectively arranged on the left side and the right side of a first front axle and a second front axle, a distance sensor is respectively arranged on the left side and the right side of a rear axle of a single-rear-axle automobile, and a distance sensor is not arranged on the rear axle of a multi-rear-axle automobile.
3. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the first step of the second step,
when the total axle load of the front axle is measured, for a single-front-axle automobile, the axle load of the front axle measured by the single-front-axle automobile is Fzf1I.e. the total axle load F of the front axle of the vehiclef0＝FZf1(ii) a For a dual front axle vehicle, the first front axle F is measured separatelyzf1And second front axle load Fzf2I.e. the total axle load F of the front axle of the vehiclef0＝FZf1+FZf2；
When measuring the total axle load of the rear axle, firstly measuring the axle load F of each axle of the rear axlezr1、Fzr2……FzrnAnd n is the rear axle sequence number, the total axle load F of the rear axle of the automobiler0＝FZr1+FZr2+……+FZrn。
4. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the second step,
when the distance Xf0 from the axle center of the front axle wheel of the automobile to the XOY plane is measured:
a: for a single front axle automobile, measuring the left axle center Xf1l0 of the front axle wheel of the automobile and the right axle center Xf1r0 of the front axle wheel of the automobile, wherein the distance Xf0 from the axle center of the front axle wheel of the automobile to an XOY plane is Xf0 ═ Xf1l0+ Xf1r 0)/2;
for a double-front-axle automobile, firstly measuring the distances from the left axle center of a first front-axle wheel, the right axle center of the first front-axle wheel, the left axle center of a second front-axle wheel and the right axle center of the second front-axle wheel to an XOY plane as Xf1l0, Xf1r0, Xf2l0 and Xf2r0 respectively, and then the distance Xf0 from the axle center of the front-axle wheel to the XOY plane is Xf0 ═ (Xf1l0+ Xf1r0+ Xf2l0+ Xf2r 0)/4;
when the distance Xf0 from the axle center of the rear axle of the automobile to the XOY plane is measured:
c: for a single-rear-axle automobile, firstly measuring a rear wheel left-side axle center Xrl0 and a rear wheel right-side axle center Xrr0 of the single-rear-axle automobile, wherein the distance Xr0 from the automobile rear axle to an XOY plane is Xr0 ═ Xrl0+ Xrr 0)/2;
d: for a multi-rear-axle automobile, the distance from the left and right side axle centers of each rear axle gear to the XOY plane is not required to be measured, and the distance Xr0 from the axle centers of the multi-rear-axle automobile to the XOY plane is the distance Xf0 from the axle centers of the front axle wheels of the double front axles to the XOY plane, namely Xr0 is Xf 0.
5. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the third step, the wheel base L of the automobile is determined
a: for a single front axle and a single rear axle automobile, the automobile wheelbase L is the distance from the axle center of the front axle to the axle center of the rear axle;
b: for a double-front-axle and single-rear-axle automobile, the automobile wheelbase L is the distance from the midpoint of the axle centers of the two front axles to the axle center of the rear axle;
c: for double-front-axle and multi-rear-axle automobiles, when the single rear axle load of the automobile is easy to measure, the wheelbase of the automobile is determined according to the wheel base
Figure FDA0003212690460000031
Performing an equivalent calculation wherein Fzr1、Fzr2……FzrnFor the axle load of each axle of the rear axle, L1 … … Ln is the distance between the midpoint of the axle centers of the two front axles and the axle center of the nth axle of the rear axle;
d: for a double-front-axle and multi-rear-axle automobile, when the single rear axle load of the automobile can not be measured, the axle distance L of the automobile is determined according to the following method:
d.1: if the rear axles of the vehicle are uniformly distributed, the wheel base of the vehicle is pressed
Figure FDA0003212690460000032
Calculating, wherein L1 … … Ln is the distance between the middle point of the axle centers of the two front axles and the nth axle center of the rear axle;
d.2: if the axle center distance of two adjacent rear axles of the automobile is less than or equal to 1.5 times of the tire radius, the two rear axles can be equivalent to one axle, the axle center is the center of the axle centers of the two rear axles, the axle load is the sum of the axle loads of the two axles, and the axle distance L is calculated by using the method c;
d.3: if the number of the rear shafts is more and a rear shaft group exists, the rear shaft group is formed by a plurality of shafts (the number of the shafts is more than or equal to 3), the distances between the axes of two continuous adjacent rear shafts are equal, the shaft group can be equivalent to one shaft, the axis is the center of the axis of the head rear shaft and the end rear shaft, the shaft load is the sum of the shaft loads of all the shafts of the shaft group, and the shaft distance L is calculated by using the method c;
when the conditions in d.1, d.2 and d.3 are satisfied simultaneously, the method of d.1 is preferably selected for calculation.
6. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the seventh step, when the height h of the mass center of the automobile is calculated, for the automobile with a single front axle and the automobile with a single rear axle, the values h are calculated respectively by using the formula (1) and the formula (2) to reduce errors, and then the average value of the values h is taken; for the automobile with double front shafts and single rear shafts and the automobile with double front shafts and multiple rear shafts, the height h of the mass center of the automobile is calculated by adopting the formula (1).
7. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the first step, the precision of the accelerator sensor is required to be greater than or equal to 0.001g, and the precision of the distance sensor is required to be greater than or equal to 0.001 m.
8. The method for calculating the measurement of the height of the center of mass of the automobile according to claim 1, wherein: in the third step, when the measured acceleration value a0 and the distance value from the axle center of the automobile wheel to the XOY surface are kept unchanged for more than 2 seconds or within 5 percent in the single test in the process of keeping the automobile in the uniform deceleration state, the test and related data are valid, otherwise, the test is invalid and the test needs to be carried out again.
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