CN103612634B - The evaluation method of distributing In-wheel motor driving electronlmobil coefficient of road adhesion - Google Patents

Abstract

The coefficient of road adhesion evaluation method of the electronlmobil of distributing In-wheel motor driving, belongs to electric vehicle engineering field.By the current wheel speed of wheel speed sensors, car speed sensor, electric machine controller Real-time Collection electronlmobil, the speed of a motor vehicle and drive torque; Calculate slip rate, vertical load and propulsive effort; Calculate the slope that u-enters current time corresponding point on curve, when slope is less than m, namely judge that the coefficient of road adhesion in this moment is as peak value of road adhesion coefficient, otherwise continue the slope calculating subsequent time; If or slope is not less than m in 1s, then getting the maximum coefficient of road adhesion calculated in 1s is relative peak value of road adhesion coefficient; By comparing the peak value of road adhesion coefficient that four tires obtain, judge that current road is homogeneous road surface, splits road surface, docking road surface or single-wheel independence road surface.Robustness of the present invention is good, can identify various different road surface preferably, is applicable to the real-time estimation of the vehicle coefficient of road adhesion on various road surface in the process of moving.

Description

The evaluation method of distributing In-wheel motor driving electronlmobil coefficient of road adhesion

Technical field

The present invention relates to the evaluation method of a kind of distributing In-wheel motor driving electronlmobil coefficient of road adhesion in the process of moving, particularly the real-time assay of the longitudinal attachment characteristic in enterprising road wheel tire and road surface on actual road surface, belongs to electric vehicle engineering field.

Background technology

Distributing In-wheel motor driving electronlmobil is arranged on by wheel hub motor in electronlmobil four wheels or near wheel respectively, there is the features such as response is fast, messenger chain is short, transmission is efficient, compact conformation, taking full advantage of motor accurate surveying and feature controlled fast, is the important developing direction of electronlmobil one.

The adhesion value variation characteristic of electronlmobil tire on different road surface is the important technology index evaluating motor tire performance, and it has material impact to automotive performance.Adhesion value variation characteristic between tire from different road surface is also an important initial parameter of vehicle dynamic quality and deceleration and stopping performance simulation calculation.

All do a lot of work in coefficient of road adhesion identification field both at home and abroad at present, mainly comprise following several method.

1) based on the coefficient of road adhesion evaluation method of coefficient of road adhesion and wheel slip slope of a curve.The method is simply easy to implement, but can only be directed to automobile when being in low slip rate, when high slip rate, does not meet linear relationship between slip rate and adhesion value.

2) based on the coefficient of road adhesion evaluation method of tire model.The method can obtain the slip characteristic of wheel by tire model, and directly estimates coefficient of road adhesion, and accuracy is higher.But its accuracy is too strong to the tire model dependence adopted, utilize complicated tire model to calculate slip rate overlong time, the tire model of simplification can affect again the accuracy of adhesion value.

Much other method is changed for prototype with these two kinds in addition, also respectively has merits and faults.

Summary of the invention

Estimate inaccurate problem for existing coefficient of road adhesion, the object of the invention is to provide a kind of coefficient of road adhesion evaluation method of distributing In-wheel motor driving electronlmobil, in order to accurately to estimate surface conditions, to make traveling safer.

For achieving the above object, the present invention takes following technical scheme:

The coefficient of road adhesion evaluation method of the electronlmobil of distributing In-wheel motor driving, the method step is:

1) set up a kind of estimating system of battery-driven car coefficient of road adhesion, comprising: be arranged on the drive torque sensor on electric machine controller, the wheel speed sensors being arranged on wheel place, car speed sensor, wheel slip computing module, coefficient of road adhesion estimation module, simplify tire model module.Coefficient of road adhesion estimation module has the algorithm estimating coefficient of road adhesion based on coefficient of road adhesion and wheelslip rate curve.

2) when ignoring tire drag, according to formula (1), real-time monitored is carried out to tire propulsive effort.

$F_i=(T_z-J_{\mathrm{\ω}}*\stackrel{\·}{\mathrm{\ω}})/R,---\left(1\right)$

In formula, R-vehicle wheel roll radius, J ω-vehicle wheel rotation inertia, -wheel angular acceleration, F _z-wheel vertical load, T _z-drive torque.

Wherein, T _zbeing drive torque, is known.If moment k-1 and k that angular speed of wheel sensor is adjacent before and after gathering, interval time is T, wheel speed signal ω (k) that Real-time Collection arrives and ω (k-1), so there is (2) formula to calculate wheel heart acceleration.

$\stackrel{\·}{\mathrm{\ω}}=\frac{\mathrm{\ω}\left(k\right)-\mathrm{\ω}(k-1)}{T},---\left(2\right)$

So the formula of obtaining (3) carries out calculating tire propulsive effort:

$F_i\left(k\right)=[T_z-J_{\mathrm{\ω}}*\frac{\mathrm{\ω}\left(k\right)-\mathrm{\ω}(k-1)}{T}]/R,---\left(3\right)$

The vertical load of distributing In-wheel motor driving electronlmobil is calculated as follows, and the vertical load of the left and right wheels before and after wherein getting is equal,

$F_{z1}=\frac{\mathrm{mg}{L}_r-\mathrm{mah}}{2L},---\left(4\right)$

$F_{z2}=\frac{\mathrm{mg}{L}_f-\mathrm{mah}}{2L},---\left(5\right)$

In formula, L _r-vehicle centroid to the vertical distance of rear axle, L _f-vehicle centroid is to the vertical distance of front-wheel wheel shaft, and the vertical distance between L-front and back wheel wheel shaft, h-vehicle centroid is to the height on ground.

Wherein, a is electronlmobil acceleration/accel, if moment k-1 and k that car speed sensor is adjacent before and after gathering, interval time is T, the wheel speed signal V(k that Real-time Collection arrives) and V(k-1), so there is (6) formula to calculate pickup.

$a=\frac{v\left(k\right)-v(k-1)}{T},$

Current coefficient of road adhesion is calculated by formula (6):

μ（k）=F _i（k）/F _zi（6）

The slip rate of current time calculates and can be calculated by formula (7):

$\mathrm{\λ}\left(k\right)=\left|\frac{\mathrm{\ω}\left(k\right)*R-v_w\left(k\right)}{\max \{\mathrm{\ω}\left(k\right)*R,v_w\left(k\right)\}}\right|,---\left(7\right)$

In formula, λ-slip rate, ω-angular speed of wheel, R-vehicle wheel roll radius, v _w-the speed of a motor vehicle.

3) through type (8) calculates current road adhesion value and slip rate slope of a curve:

$p=\frac{\mathrm{d\μ}}{\mathrm{d\λ}}=\frac{\mathrm{\μ}\left(k\right)-\mathrm{\μ}(k-1)}{\mathrm{\λ}\left(k\right)-\mathrm{\λ}(k-1)}---\left(8\right)$

Relatively: | p|<m, (9)

Wherein, m is setting value;

I) when | during p|<m, can judge that current coefficient of road adhesion is peak road adhesion value, and zone bit flag=0 is set; If the absolute value of slope p | p|>m, then continue the slope p calculating subsequent time, until | p|<m;

If ii) in 1s, slope p does not still reach | p|<m, being then taken at the maximum coefficient of road adhesion calculated in 1s is relative peak value of road adhesion coefficient, and sets up a zone bit flag=1;

4) calculate peak value of road adhesion coefficient and the zone bit of four tires respectively, be designated as u1, u2, u3, u4, flag1, flag2, flag3, flag4; Wherein, u1, flag1 represent peak value of road adhesion coefficient and the zone bit of the near front wheel; U2, flag2 represent peak value of road adhesion coefficient and the zone bit of off front wheel; U3, flag3 represent peak value of road adhesion coefficient and the zone bit of left rear wheel; U4, flag4 represent peak value of road adhesion coefficient and the zone bit of off hind wheel;

Compare peak value of road adhesion coefficient u1, u2, u3, u4 and zone bit flag1, flag2, flag3, flag4 of four tires; Judge that current road is homogeneous road surface, splits road surface, docking road surface or single-wheel independence road surface further;

If the zone bit of four tires is identical, the difference of peak value of road adhesion coefficient is in n, and n is setting value, then judge that current road is as homogeneous road surface, its coefficient of road adhesion U=(u1+u2+u3+u4)/4;

If the first two tire is identical with latter two designation of tyres position, and the difference of peak value of road coefficient is respectively all in n, and n is setting value, then judge that current road is as docking road surface, its coefficient of road adhesion U1=(u1+u2)/2, U2=(u3+u4)/2;

If two, left side tire is identical with designation of tyres position, two, the right, and the difference of coefficient of road adhesion is respectively all in n, and n is setting value, then judge that current road is as splitting road surface, its coefficient of road adhesion U1=(u1+u3)/2, U2=(u2+u4)/2;

If do not meet above-mentioned situation, then judge that current road is as single-wheel independence road surface, coefficient of road adhesion according to circumstances calculates.

The present invention is owing to taking above technical scheme, it has the following advantages: first the present invention by the current wheel speed of wheel speed sensors, car speed sensor and electric machine controller Real-time Collection electronlmobil, the speed of a motor vehicle and drive torque, then calculates current slip rate, vertical load and the propulsive effort of four tires respectively.Calculated the slope of current time corresponding point on μ-λ curves by these three values, when slope close to zero time, namely judge that the coefficient of road adhesion in this moment is as peak value of road adhesion coefficient, otherwise continue the slope calculating subsequent time; If or slope is not close to zero in 1s, then getting the maximum coefficient of road adhesion calculated in 1s is relative peak value of road adhesion coefficient.By comparing the coefficient of road adhesion calculated by four tires, judge that current road is homogeneous road surface, splits road surface, docking road surface or single-wheel independence road surface.Robustness of the present invention is good, can identify various different road surface preferably, is applicable to the real-time estimation of the vehicle coefficient of road adhesion on various road surface in the process of moving.

Accompanying drawing explanation

Fig. 1 is phylogenetic relationship schematic diagram of the present invention.

Fig. 2 is method flow diagram of the present invention.

Detailed description of the invention

Describe the present invention below in conjunction with drawings and Examples.

Fig. 1 is phylogenetic relationship schematic diagram of the present invention.System comprises a vehicular drive moment sensor, wheel speed sensors, speed of a motor vehicle observer as shown in Figure 1.Coefficient of road adhesion estimation block, comprises tire force estimation module, wheel slip computing module and simplifies tire model.

Based on above system, the real-time estimation method of the present invention to the coefficient of road adhesion in vehicle travel process comprises the following steps, as shown in Figure 2 (Fig. 2 is method flow diagram of the present invention).

The coefficient of road adhesion evaluation method of the electronlmobil of distributing In-wheel motor driving, the method step is:

1) when ignoring tire drag, according to formula (1), real-time monitored is carried out to tire propulsive effort.

$F_i=(T_z-J_{\mathrm{\&omega;}}*\stackrel{\&CenterDot;}{\mathrm{\&omega;}})/R,---\left(1\right)$

In formula, R-vehicle wheel roll radius, J ω-vehicle wheel rotation inertia, -wheel angular acceleration, F _z-wheel vertical load, T _z-drive torque.

Wherein, T _zbeing drive torque, is known.If moment k-1 and k that angular speed of wheel sensor is adjacent before and after gathering, interval time is T, wheel speed signal ω (k) that Real-time Collection arrives and ω (k-1), so there is (2) formula to calculate wheel heart acceleration.

$\stackrel{\&CenterDot;}{\mathrm{\&omega;}}=\frac{\mathrm{\&omega;}\left(k\right)-\mathrm{\&omega;}(k-1)}{T},---\left(2\right)$

So the formula of obtaining (3) carries out calculating tire propulsive effort:

$F_i\left(k\right)=[T_z-J_{\mathrm{\&omega;}}*\frac{\mathrm{\&omega;}\left(k\right)-\mathrm{\&omega;}(k-1)}{T}]/R,---\left(3\right)$

The vertical load of distributing In-wheel motor driving electronlmobil is calculated as follows, and the vertical load of the left and right wheels before and after wherein getting is equal,

$F_{z1}=\frac{\mathrm{mg}{L}_r-\mathrm{mah}}{2L},---\left(4\right)$

$F_{z2}=\frac{\mathrm{mg}{L}_f-\mathrm{mah}}{2L},---\left(5\right)$

In formula, L _r-vehicle centroid to the vertical distance of rear axle, L _f-vehicle centroid is to the vertical distance of front-wheel wheel shaft, and the vertical distance between L-front and back wheel wheel shaft, h-vehicle centroid is to the height on ground.

Wherein, a is electronlmobil acceleration/accel, if moment k-1 and k that car speed sensor is adjacent before and after gathering, interval time is T, the wheel speed signal v(k that Real-time Collection arrives) and v(k-1), so there is (6) formula to calculate pickup.

$a=\frac{v\left(k\right)-v(k-1)}{T},$

The current coefficient of road adhesion that utilizes can be calculated by formula (6):

μ（k）=F _i（k）/F _zi，（6）

The slip rate of current time calculates and can be calculated by formula (7):

$\mathrm{\&lambda;}\left(k\right)=\left|\frac{\mathrm{\&omega;}\left(k\right)*R-v_w\left(k\right)}{\max \{\mathrm{\&omega;}\left(k\right)*R,v_w\left(k\right)\}}\right|,---\left(7\right)$

In formula, λ-slip rate, ω-angular speed of wheel, R-vehicle wheel roll radius, v _w-the speed of a motor vehicle.

2) through type (8) calculates current road adhesion value and slip rate slope of a curve:

$p=\frac{\mathrm{d\&mu;}}{\mathrm{d\&lambda;}}=\frac{\mathrm{\&mu;}\left(k\right)-\mathrm{\&mu;}(k-1)}{\mathrm{\&lambda;}\left(k\right)-\mathrm{\&lambda;}(k-1)}---\left(8\right)$

Relatively: | p|<m, (9),

Wherein, m is 0.1 here; N is 0.05.

I) when | during p|<0.1, can judge that current coefficient of road adhesion is peak road adhesion value, and zone bit flag=0 is set; If the absolute value of slope p | p|>0.1, then continue the slope p calculating subsequent time, until | p|<0.1;

If ii) in 1s, slope p does not still reach | p|<0.1, being then taken at the maximum coefficient of road adhesion calculated in 1s is relative peak value of road adhesion coefficient, and sets up a zone bit flag=1;

3) calculate peak value of road adhesion coefficient and the zone bit of four tires respectively, be designated as u1, u2, u3, u4, flag1, flag2, flag3, flag4; Wherein, u1, flag1 represent peak value of road adhesion coefficient and the zone bit of the near front wheel; U2, flag2 represent peak value of road adhesion coefficient and the zone bit of off front wheel; U3, flag3 represent peak value of road adhesion coefficient and the zone bit of left rear wheel; U4, flag4 represent peak value of road adhesion coefficient and the zone bit of off hind wheel;

Compare peak value of road adhesion coefficient u1, u2, u3, u4 and zone bit flag1, flag2, flag3, flag4 of four tires; Judge that current road is homogeneous road surface, splits road surface, docking road surface or single-wheel independence road surface further;

If the zone bit of four tires is identical, the difference of peak value of road adhesion coefficient is in n, and n is setting value, then judge that current road is as homogeneous road surface, its coefficient of road adhesion U=(u1+u2+u3+u4)/4;

If the first two tire is identical with latter two designation of tyres position, and the difference of peak value of road coefficient is respectively all in n, and n is setting value, then judge that current road is as docking road surface, its coefficient of road adhesion U1=(u1+u2)/2, U2=(u3+u4)/2;

If two, left side tire is identical with designation of tyres position, two, the right, and the difference of coefficient of road adhesion is respectively all in n, and n is setting value, then judge that current road is as splitting road surface, its coefficient of road adhesion U1=(u1+u3)/2, U2=(u2+u4)/2;

If do not meet above-mentioned situation, then judge that current road is as single-wheel independence road surface, coefficient of road adhesion according to circumstances calculates.

The present invention is owing to taking above technical scheme, it has the following advantages: first the present invention by the current wheel speed of wheel speed sensors, car speed sensor and electric machine controller Real-time Collection electronlmobil, the speed of a motor vehicle and drive torque, then calculates current slip rate, vertical load and the propulsive effort of four tires respectively.Calculated the slope of current time corresponding point on μ-λ curves by these three values, when slope close to zero time, namely judge that the coefficient of road adhesion in this moment is as peak value of road adhesion coefficient.By comparing the coefficient of road adhesion calculated by four tires, judge that current road is homogeneous road surface, splits road surface, docking road surface or single-wheel independence road surface.Robustness of the present invention is good, can identify various different road surface preferably, is applicable to the real-time estimation of the vehicle coefficient of road adhesion on various road surface in the process of moving.

Claims (3)

1. the evaluation method of distributing In-wheel motor driving electronlmobil coefficient of road adhesion, is characterized in that, the method contains in steps:

1) ignore tire drag, according to formula (1), real-time monitored is carried out to tire propulsive effort;

Described formula (1) is: $F_i=(T_z-J_{\mathrm{\&omega;}}*\stackrel{\&CenterDot;}{\mathrm{\&omega;}})/R,---\left(1\right)$

In formula, R-vehicle wheel roll radius, J _ω-vehicle wheel rotation inertia, -wheel angular acceleration, F _z-wheel vertical load, T _z-drive torque;

Wherein, T _zbeing drive torque, is known; If moment k-1 and k that angular speed of wheel sensor is adjacent before and after gathering, interval time is T, wheel speed signal ω (k) that Real-time Collection arrives and ω (k-1), so calculate wheel heart acceleration by formula (2):

$\stackrel{\&CenterDot;}{\mathrm{\&omega;}}=\frac{\mathrm{\&omega;}\left(k\right)-\mathrm{\&omega;}(k-1)}{T},---\left(2\right)$

Calculating tire propulsive effort is carried out according to formula (3):

$F_i\left(k\right)=[T_z-J_{\mathrm{\&omega;}}*\frac{\mathrm{\&omega;}\left(k\right)-\mathrm{\&omega;}(k-1)}{T}]/R,---\left(3\right)$

The vertical load of distributing In-wheel motor driving electronlmobil is calculated as follows, and the vertical load of the left and right wheels before and after wherein getting is equal, that is:

$F_{z1}=\frac{\mathrm{mg}{L}_r-\mathrm{mah}}{2L},---\left(4\right)$

$F_{z2}=\frac{\mathrm{mg}{L}_f-\mathrm{mah}}{2L},---\left(5\right)$

In formula, L _r-vehicle centroid to the vertical distance of rear axle, L _f-vehicle centroid to the vertical distance of front-wheel wheel shaft, the vertical distance between L-front and back wheel wheel shaft, h-vehicle centroid is to the height on ground;

Wherein, a is electronlmobil acceleration/accel, if moment k-1 and k that car speed sensor is adjacent before and after gathering, interval time is T, the wheel speed signal v(k that Real-time Collection arrives) and v(k-1), so calculate pickup by following formula:

$a=\frac{v\left(k\right)-v(k-1)}{T},$

Current coefficient of road adhesion is calculated by formula (6):

μ（k）=F _i（k）/F _zi（6）

The slip rate of current time calculates and can be calculated by formula (7):

$\mathrm{\&lambda;}\left(k\right)=\left|\frac{\mathrm{\&omega;}\left(k\right)*R-v_w\left(k\right)}{\max \{\mathrm{\&omega;}\left(k\right)*R,v_w\left(k\right)\}}\right|,---\left(7\right)$

In formula, λ-slip rate, ω-angular speed of wheel, R-vehicle wheel roll radius, v _w-the speed of a motor vehicle;

2) through type (8) calculates current road adhesion value and slip rate slope of a curve p:

$p=\frac{\mathrm{d\&mu;}}{\mathrm{d\&lambda;}}=\frac{\mathrm{\&mu;}\left(k\right)-\mathrm{\&mu;}(k-1)}{\mathrm{\&lambda;}\left(k\right)-\mathrm{\&lambda;}(k-1)}---\left(8\right)$

Relatively: | p|<m, (9)

Wherein, m is setting value;

When | during p|<m, can judge that current coefficient of road adhesion is peak road adhesion value, and zone bit flag=0 is set; If | p|>m, then continue the slope p calculating subsequent time, until | p|<m;

If slope p does not still reach in 1s | p|<m, being then taken at the maximum coefficient of road adhesion calculated in 1s is relative peak value of road adhesion coefficient, and sets up a zone bit flag=1;

3) calculate peak value of road adhesion coefficient and the zone bit of four tires respectively, be designated as u1, u2, u3, u4, flag1, flag2, flag3, flag4; Wherein, u1, flag1 represent peak value of road adhesion coefficient and the zone bit of the near front wheel; U2, flag2 represent peak value of road adhesion coefficient and the zone bit of off front wheel; U3, flag3 represent peak value of road adhesion coefficient and the zone bit of left rear wheel; U4, flag4 represent peak value of road adhesion coefficient and the zone bit of off hind wheel;

Compare peak value of road adhesion coefficient u1, u2, u3, u4 and zone bit flag1, flag2, flag3, flag4 of four tires; Judge that current road is homogeneous road surface, splits road surface, docking road surface or single-wheel independence road surface further;

If the zone bit of four tires is identical, the difference of peak value of road adhesion coefficient is in n, and n is setting value, then judge that current road is as homogeneous road surface, its coefficient of road adhesion U=(u1+u2+u3+u4)/4;

If the first two tire is identical with latter two designation of tyres position, and the difference of peak value of road coefficient is respectively all in n, and n is setting value, then judge that current road is as docking road surface, its coefficient of road adhesion U1=(u1+u2)/2, U2=(u3+u4)/2;

If two, left side tire is identical with designation of tyres position, two, the right, and the difference of coefficient of road adhesion is respectively all in n, and n is setting value, then judge that current road is as splitting road surface, its coefficient of road adhesion U1=(u1+u3)/2, U2=(u2+u4)/2;

If do not meet above-mentioned situation, then judge that current road is as single-wheel independence road surface, coefficient of road adhesion according to circumstances calculates.

2. the evaluation method of distributing In-wheel motor driving electronlmobil coefficient of road adhesion according to claim 1, it is characterized in that, described m is 0.1.

3. the evaluation method of distributing In-wheel motor driving electronlmobil coefficient of road adhesion according to claim 1, it is characterized in that, described n is 0.05.