CN106773714A - A kind of wheel-hub motor driven vehicle control method based on self-regulation particle model - Google Patents

Abstract

The application is related to a kind of wheel-hub motor driven vehicle control method based on self-regulation particle model, the self-regulation particle model is set up according to dynamics of vehicle principle, suitable for the linear processes region of vehicle, rational state of motion of vehicle reference value under the limit of adhesion of road surface can be especially provided, to ensure the control stability and driving safety of vehicle.The foundation of the self-regulation particle reference model is comprised the steps of：First, according to dynamics of vehicle neutral steer characteristic, the Changing Pattern of vehicle desired reference side acceleration is obtained with two degrees of freedom linear reference model analyzing；2nd, vehicle has longitudinal acceleration and side acceleration demand simultaneously when, set up in G G acceleration friction circles from the one-to-one mapping function MAP relations with reference to resultant acceleration to preferable resultant acceleration；3rd, by the conversion between vehicle movement trajectory coordinates system and vehicle centroid coordinate system, vehicle desired reference state of motion value is obtained.Control stability and active safety of the vehicle under limit of adhesion are ensure that, and ensures controllability of the driver to vehicle.

Description

A kind of wheel-hub motor driven vehicle control method based on self-regulation particle model

Technical field

The application is related to a kind of control method of wheel-hub motor driven vehicle, more particularly to based on self-regulation particle model, Method suitable for providing reasonable state of motion of vehicle value under the limit of adhesion of road surface.

Background technology

Wheel-hub motor driven vehicle is one of study hotspot in current electric automobile field, when wheel-hub motor driven vehicle When operating in limit of adhesion, it usually needs reference model provides rational vehicle reference state of motion value, could veritably play The performance advantage of wheel-hub motor driven vehicle.Vehicle is typically generated as reference model using two degrees of freedom linear model at present Control system reference state value.However, two degrees of freedom linear model has the limitation in terms of three below：(a) two degrees of freedom Model is linear, only represents fundamental characteristics of the vehicle in the range of linearity of the side acceleration less than 0.4g, it is impossible to true Dynamics of the reflection vehicle in nonlinear area (big side acceleration)；(b) near surface-tire limit of adhesion, two Degrees of Freedom Model will provide irrational dynamics of vehicle state value；C () exceeds road surface limit of adhesion when vehicle demand generalized force When, vehicle target state value will in a certain way reach saturation, now should be defeated using non-linear reference model parsing driver Enter signal；Otherwise, driver's input signal will become very micro- with the relation that intercouples of vehicle target track in saturation point Weak, in other words, driver will lose the controllability to vehicle driving trace.

Accordingly, it would be desirable to a kind of reference model suitable for linear processes region is set up, to ensure vehicle in attachment pole Control stability and active safety under limit, and ensure controllability of the driver to vehicle.

The content of the invention

For the technical problem that above-mentioned this area is present, the invention provides a kind of self-regulation of wheel-hub motor driven vehicle Particle model.Tire friction circle is applied to vehicle aspect by the model, so as to regard the vehicle in motion as particle (part Icle) it is modeled.The structure of the model specifically includes following steps：

1. vehicles at the uniform velocity negotiation of bends when, according to driver's input signal, by vehicle two degrees of freedom linear reference model Parsing obtains vehicle reference side acceleration；And according to dynamics of vehicle neutral steer characteristic, set up preferable side acceleration with The Changing Pattern with reference to side acceleration, that is, is exactly, the product of vehicle reference side acceleration and preferable side acceleration is Vehicle road attachment coefficient and acceleration of gravity product square, and then vehicle can be obtained in linear and nonlinear area, especially It is rational state of motion value under limit of adhesion.

2. during the non-at the uniform velocity negotiation of bends of vehicles, while have longitudinal acceleration and side acceleration demand, in vehicle friction circle In, build with reference to the self-regulation particle mapping relations between resultant acceleration and preferable resultant acceleration, obtain preferable resultant acceleration arrow Amount；

3. vehicle ideal resultant acceleration vector is transformed into vehicle centroid coordinate by by vehicle movement trajectory coordinates system System, obtains vehicle desired reference state of motion value.

The step 1. in by be self-regulated particle model parse obtain vehicle ideal side acceleration, specifically include：When Vehicle there was only the side acceleration demand of driver's input and parsing refers to side accelerationWhen, apply one to vehicle The preferable resultant acceleration of individual side acceleration and braking acceleration, and the preferable resultant acceleration and vehicle centroid sum velocity direction In obtuse angle；According to referring to side accelerationWith preferable side accelerationProduct be equal to vehicle road attachment coefficient μ and weight Power acceleration g product square relation, obtain vehicle ideal side acceleration：

The step 2. obtain vehicle ideal resultant acceleration, specifically include：In the self-regulation particle mapping relations, When the reference side acceleration of vehicleWith reference to longitudinal accelerationWith preferable side accelerationPreferable longitudinal accelerationWhen there is following relation：

Wherein, φ is offset angle, is the angle with reference to the ray on resultant acceleration mapping vehicle friction circle with abscissa；It is logical Cross equation below and determine preferable resultant acceleration：

When the reference side acceleration of vehicleWith reference to longitudinal accelerationWith preferable side accelerationIt is vertical with ideal To accelerationWhen there is following relation：

Preferable resultant acceleration is then determined by equation below：

Step realization 3. uses equation below：

Wherein, β is vehicle centroid side drift angle,It is longitudinal acceleration of the vehicle in geocentric coordinate system,It is that vehicle exists Side acceleration in geocentric coordinate system.

When the vehicle centroid drift angle β is 0, vehicle reference dynamics state value can be represented with equation below：

Wherein, v_xIt is the initial longitudinal velocity of vehicle；It is preferable longitudinal velocity of the vehicle in its geocentric coordinate system, r^ref It is yaw rate.

The above method provided by the present invention is applied to the linear processes region of vehicle, it is possible to provide road surface limit of adhesion Rational state of motion of vehicle reference value down, it can be ensured that the control stability and driving safety of vehicle.

Brief description of the drawings

Schematic diagram of the accompanying drawing 1 for self-regulation particle model in vehicle friction circle

Accompanying drawing 2 is that driver is parsed with reference to resultant acceleration to MPR desired reference resultant accelerations in G-G figure first quartiles Mapping

Accompanying drawing 3 is MPR mapping-normalized G-G of driver's parsing with reference to resultant acceleration to desired reference resultant acceleration Figure

Accompanying drawing 4 is that conversion of the vehicle ideal resultant acceleration between vehicle movement coordinate system and vehicle centroid coordinate system is illustrated Figure

Specific embodiment

The present invention refers both to the acceleration of vehicle with each acceleration in vehicle generally research object, therefore literary invention.

Known, tire as a research object, there is the limit in the earth-grasping force of tire during Vehicular turn, though Right earth-grasping force total amount is limited, but how to distribute and do not limit but, can simultaneously distribute to acceleration and turn to, or slow down With steering, then known utilization friction circle describe tire earth-grasping force consumption with distribution.Due to the present invention using vehicle it is overall as Research object, thus using above-mentioned tire friction circle concept propose vehicle friction circle come describe vehicle entirety earth-grasping force consumption with Distribution.

In the present invention, will be in the particle model that is self-regulated, with reference to the ray on the point mapping vehicle friction circle of resultant acceleration It is referred to as offset angle with the angle of abscissa, alphabetical φ is represented.Vehicle accelerate turning condition (existing longitudinal acceleration demand, and Have side acceleration demand) under, if lateral dynamics are preferential, optimal selection is φ=0；If instead longitudinal dynamics Preferentially, then φ ＞ 0 are taken.In general, offset angle φ is considered a design parameter, and according to driving style and human factor Adjusted etc. various criterion.

In self-regulation particle model in the present invention, with reference to resultant acceleration and the functional relation of preferable resultant acceleration, it is also With reference to the mapping in resultant acceleration to vehicle friction circle, be referred to as self-regulated particle mapping or MPR mappings.

The present invention will be described in further detail below in conjunction with the accompanying drawings.As shown in Figure 1, A is represented and is used two degrees of freedom line Property the reference resultant acceleration that obtains of model analyzing, A ' represents the preferable resultant acceleration obtained using the particle model parsing that is self-regulated.

Vehicle at the uniform velocity negotiation of bends when, according to driver be input into signal, by be self-regulated particle model parse managed Think side acceleration, A ' in such as Fig. 1.Specifically include：Obtain with reference to lateral when vehicle only side acceleration demand and parsing plus SpeedWhen, the resultant acceleration vector of a side acceleration and braking acceleration is applied to vehicle, and resultant acceleration is sweared Amount is with vehicle centroid sum velocity direction in obtuse angle；According to referring to side accelerationAnd preferable side acceleration (OB)(OC) Product be equal to vehicle road attachment coefficient μ and gravity acceleration g product square relation, obtain preferable side acceleration

Parsing refers to side accelerationWith preferable side accelerationMeet right angled triangle projective theorem：Can obtain

It is to set up parsing with reference to the mapping in resultant acceleration to vehicle friction circle, this hair during the non-at the uniform velocity negotiation of bends of vehicle , in the case where turning condition, the effect of different offset angle is accelerated, vehicle ideal side acceleration is with referring to resultant acceleration for bright analysis vehicle Changing Pattern.As shown in Fig. 2 Fang Dian represents the reference resultant acceleration that the parsing of two degrees of freedom linear model is obtained, round dot in figure The preferable resultant acceleration that table is obtained according to self-regulation particle model.In figure, in vehicle friction circle diagram, first quartile is divided into four Individual part：1., 2., 3., 4., wherein the region 1., 2., 3., being 4. partly all beyond vehicle friction circle.

As shown in Figure 2, region is 3. representative, and with region, 3. C points example is briefly described below, and C is represented and used two The reference resultant acceleration that the parsing of free degree linear model is obtained.

C′₀C′₁C₂C₂C₃It is the preferable resultant acceleration obtained using the particle model parsing that is self-regulated.

Using point C as starting point, one of mapping selection is to reduce longitudinal demand to zero, i.e. selection horizontal map C → C₀, then with the MPR mappings under the pure side acceleration demand shown in accompanying drawing 1, C₀→C′₀.Obviously, leaned on reference to resultant acceleration Nearly a_yDuring axle, this mapping is also continuous.More generally other mapping selections include an offset angle φ, i.e., reduce longitudinal direction simultaneously With side acceleration demand, for example：C→C₁→C′₁。

On the premise of φ ＜ pi/2s, with reference to resultant acceleration a^DINear a_yDuring axle, this mapping is continuous.2. and 4. region Offset angle φ should be bounded, to avoid the reverse sign of side acceleration symbol.

In accompanying drawing 2, specific mapping is as follows：

(a) region 1. in, driver refers to resultant accelerationWith preferable resultant accelerationBetween Relation be represented by：

A_iIt is the preferable resultant acceleration under different offset angles, such as A₀、A₁、A₂, the effective range of offset angle φ is 0≤φ ＜ π/2。

(b) region 2. in, driver is with reference to resultant acceleration B and preferable resultant acceleration B_iThe relation of the two and region 1. in It is the same；The difference is that the effective range of offset angle φ is different, i.e.,

(c) region 3. in, if 0=φ, the MPR mapping points under corresponding pure side acceleration demand are C₀, then Follow the theories of the MPR under pure side acceleration demand as shown in Figure 1 and reference acceleration is mapped to the upper point of vehicle friction circle C′₀；

IfCorresponding MPR mapping points are C₁, then follow as shown in Figure 3 is pure MPR theories under side acceleration demand will be mapped to point C ' on vehicle friction circle with reference to resultant acceleration₁；

IfCorresponding MPR mapping points are C2；

Therefore ifCorresponding acceleration point is C₀、C₁Or C₂, driver's reference Resultant accelerationWith preferable resultant accelerationBetween relation be represented by：

Then the theories of the MPR under pure side acceleration demand are followed reference acceleration is mapped to the upper point of vehicle friction circle C′₀、C′₁、C₂, as shown in Figure 2.

Otherwise, ifCorresponding MPR acceleration points are C₃Or C₄, and region 1. phase Together.

(d) region 4. in mapping and region 3. in mapping it is basically identical, unlike offset angle φ workspace Domain.

Vehicle is analyzed above in the case where turning condition is accelerated, different offset angles are to vehicle ideal longitudinal acceleration and laterally add Speed affecting laws all, this affecting laws are applied equally to the retarding braking operating mode of vehicle.When vehicle adheres on road surface Under the limit during decelerating turn, in the second quadrant of vehicle friction figure, φ ＞ 0 (turn to and braking be combined,) more close It is suitable, highlight deceleration.The mapping for ultimately generating is displayed in normalization vehicle friction circle, as shown in Figure 3.

MPR mappings shown in accompanying drawing 3, upper lower half-plane mapping is symmetrical, and the mapping of left and right plane is asymmetric (braking/accelerate)；Fang Dian represents the reference resultant acceleration that the parsing of two degrees of freedom linear model is obtained in figure, and round dot table is according to self-regulated The preferable resultant acceleration that section particle model is obtained.When driver parses acceleration demandArea where point D or G Domain, preferable resultant acceleration is represented by：

Region where the input acceleration demand of driver's parsing is located at point E (or F), the output adjusted by MPR Preferable resultant acceleration may be defined as：

The reference resultant acceleration vector obtained from above-mentioned self-regulation particle model is in track of vehicle coordinate system (x, y), x Axle is the vehicle centroid direction of motion, and y-axis is perpendicular to x-axis；And vehicle-state value general expression is at vehicle centroid coordinate system (X, Y) On, as shown in Figure 4, the angle wherein between x-axis and X-axis is vehicle centroid side drift angle β.Realize that desired reference is closed by following formula to add Conversion of the speed between track of vehicle coordinate system and vehicle centroid coordinate system：

Wherein,It is longitudinal acceleration of the vehicle in geocentric coordinate system,It is lateral in geocentric coordinate system vehicle Acceleration.

When the reference value of vehicle centroid side drift angle is set to zero, vehicle reference dynamics state value can use equation below table Show：

Wherein, v_xIt is the initial longitudinal velocity of vehicle；It is preferable longitudinal velocity of the vehicle in its geocentric coordinate system, r^ref It is yaw rate.

Although an embodiment of the present invention has been shown and described, for the ordinary skill in the art, can be with Understanding can carry out various changes, modification, replacement to these embodiments without departing from the principles and spirit of the present invention And modification, the scope of the present invention be defined by the appended.

Claims (5)

1. it is a kind of based on self-regulation particle model wheel-hub motor driven vehicle control method, it is characterised in that：

With reference to resultant acceleration, obtained by the parsing of vehicle two degrees of freedom linear model；

Vehicle friction is justified, the relation of vehicle entirety earth-grasping force consumption and distribution；

Self-regulation particle mapping relations, are, by reference to the mapping in resultant acceleration to vehicle friction circle, to obtain preferable conjunction and accelerate The functional relation of degree；

Specifically include following steps：

1. vehicles at the uniform velocity turning driving when, according to the signal that driver is input into, parsed by the particle reference model that is self-regulated preferable Side acceleration；

2. during the non-at the uniform velocity turning driving of vehicles, in vehicle friction circle, according to the self-regulation particle mapping relations, obtain To preferable resultant acceleration；

3. the preferable resultant acceleration is transformed into vehicle centroid coordinate system by by vehicle movement trajectory coordinates system, obtains vehicle reason Want to refer to state of motion value.

2. the method for claim 1, it is characterised in that：1. the step specifically includes：When vehicle only has driver defeated The side acceleration demand that enters and parsing refers to side accelerationWhen, with reference to side accelerationLaterally add with preferable SpeedProduct be equal to vehicle road attachment coefficient μ and gravity acceleration g product square, obtain vehicle it is preferable lateral plus Speed：

$a_y^{ref}=\frac{{\left(\mathrm{\μ}g\right)}^2}{a_y^{DI}}---\left(1\right).$

3. the method for claim 1, it is characterised in that：

Offset angle, is the angle of the ray and abscissa that are mapped to reference to resultant acceleration on vehicle friction circle；

The step 2. obtain preferable resultant acceleration, specifically include：In the self-regulation particle mapping relations, when vehicle With reference to side accelerationWith reference to longitudinal accelerationWith preferable side accelerationPreferable longitudinal accelerationIn the presence of with During lower relation：

$\left\{\begin{array}{c}{\left(a_x^{ref}\right)}^2+{\left(a_y^{ref}\right)}^2={\left(\mathrm{\μ}g\right)}^2\\ tan\mathrm{\φ}=\frac{a_y^{DI}-a_y^{ref}}{a_x^{DI}-a_x^{ref}}\end{array}\right.---\left(2\right)$

Wherein, φ is offset angle；Preferable resultant acceleration is determined by equation below：

$\begin{array}{c}{a}_y^{ref}=a_y^{DI}\\ a_x^{ref}=sign\left(a_x^{DI}\right)\·\sqrt{{\left(\mathrm{\μ}g\right)}^2-{\left(a_y^{ref}\right)}^2}\end{array}---\left(3\right);$

When the reference side acceleration of vehicleWith reference to longitudinal accelerationWith preferable side accelerationAdd with preferable longitudinal direction SpeedWhen there is following relation：

$\left\{\begin{array}{c}{a}_x^{{\mathrm{ref}}^{\′}}=0\\ a_y^{{\mathrm{ref}}^{\′}}=a_y^{DI}-\tan \mathrm{\φ}\·a_x^{DI}\end{array}\right.---\left(4\right)$

Preferable resultant acceleration is then determined by equation below：

$\left\{\begin{array}{c}{a}_y^{ref}=\frac{{\left(\mathrm{\μ}g\right)}^2}{a_y^{DI}}\\ a_x^{ref}=-\sqrt{{\left(\mathrm{\μ}g\right)}^2-{\left(a_y^{ref}\right)}^2}\end{array}\right.---\left(5\right).$

4. the method for claim 1, it is characterised in that：Step realization 3. uses equation below：

$\left[\begin{array}{c}{a}_X^{ref}\\ a_Y^{ref}\end{array}\right]=\left[\begin{array}{cc}cos\mathrm{\β}& -sin\mathrm{\β}\\ sin\mathrm{\β}& \cos \mathrm{\β}\end{array}\right]\left[\begin{array}{c}{a}_x^{ref}\\ a_y^{ref}\end{array}\right]---\left(6\right)$

Wherein, β is vehicle centroid side drift angle,It is longitudinal acceleration of the vehicle in geocentric coordinate system,It is vehicle in barycenter Side acceleration in coordinate system.

5. method as claimed in claim 4, it is characterised in that：When the vehicle centroid drift angle β is 0, vehicle reference power Learning state value can be represented with equation below：

$\left\{\begin{array}{c}{v}_x^{ref}=v_x+\∫a_x^{ref}dt\\ r^{ref}=\frac{a_y^{ref}}{v_x^{ref}}\end{array}\right.---\left(7\right)$

Wherein, v_xIt is the initial longitudinal velocity of vehicle；It is preferable longitudinal velocity of the vehicle in its geocentric coordinate system, r^refIt is car Yaw velocity.