CN104843057A - Steering control method for four-wheel-independence-steering automobile - Google Patents

Abstract

The invention belongs to the technical field of automobile steering control and relates to a steering control method for a four-wheel independent steering automobile. The steering control method includes: (1) by the aid of a data acquiring and processing module, acquiring and processing driver's steering intention information and automobile state information in real time; (2) by the aid of a steering mode judging module, judging a target steering mode as one of an adjusting mode, a four-wheel mode, a transition mode I or a transition mode II according to the data information in the step (1); (3) by the aid of a wheel steering angle calculating module, calculating wheel steering angles in the adjusting mode and wheel steering angles in the four-wheel mode according to the data information in the step (1); (4) by the aid of a steering mode coordination module, determining an executed steering mode of the automobile, calculating final wheel steering angles and transmitting to an execution module for execution according to results of the step (2) and the step (3). The steering control method for the four-wheel independent steering automobile has the advantages that the steering control problem of the four-wheel independent steering automobile is solved, use ratio of lateral force of wheels is increased, steering stability and steering safety of the automobile are improved, and energy consumption in steering is reduced.

Description

A kind of rotating direction control method of four-wheel independent steering automobile

Technical field

The invention belongs to motor turning control technology field, especially relate to a kind of rotating direction control method of four-wheel independent steering automobile.

Background technology

Along with improving constantly of automotive performance and road speed, the steering stability of automobile and safety are the hot issues in vehicle dynamics research always, the stability especially during high speed steering and safety problem.As a kind of important motor turning control technology, four-wheel steering technology has just got more and more people's extensive concerning since birth.Compared with traditional front-wheel steering technology, the trailing wheel of four-wheel steering technical controlling automobile participates in divertical motion together with front-wheel, with this improve stability when automobile high-speed turns to and low speed rotation to time manoevreability.According to the difference of control program, four-wheel steering technology can be divided into three classes: 1. active rear steer technology, is also called traditional four-wheel steering technology; 2. active four-wheel steering technology; 3. four-wheel independent steering technology.

In active rear steer technology, the front-wheel of automobile is controlled by bearing circle by chaufeur, and trailing wheel is controlled according to the speed of a motor vehicle and front wheel angle by steering control system.Because active rear steer control system only has trailing wheel corner controlling quantity, and it selects one of side slip angle or yaw velocity as control objectives usually, improves very limited to the steering stability of automobile.

Initiatively four-wheel steering combine with technique active front and active rear steer technology, this kind of technology utilization orientation dish corner, as steering order, is calculated front-wheel and the trailing wheel corner of automobile simultaneously according to steering wheel angle by controller.Initiatively four-wheel steering technology overcomes the shortcoming of active rear steer technology, can meet side slip angle or yaw velocity two indices simultaneously.But, it is equal separately with two trailing wheel corners that active 4-wheel Steering Control System gives tacit consent to two front wheel angles, because vertical load shifts each wheel side force difference caused when have ignored motor turning, do not realize the further raising of steering stability by reasonable distribution side force of tire.In addition, embody with rotating of steering wheel merely and turn to intention, also have ignored fine setting trimming process during automobile straight-line travelling, cause the unnecessary consumption of energy.

Summary of the invention

The object of the invention is the rotating direction control method that a kind of four-wheel independent steering automobile is provided to overcome above-mentioned the deficiencies in the prior art, effectively solve the course changing control problem of four-wheel independent steering automobile, improve side force of tire degree of utilization, improve steering stability and the safety of four-wheel independent steering automobile, that reduces automobile turns to energy consumption simultaneously.

Object of the present invention can be achieved through the following technical solutions:

A rotating direction control method for four-wheel independent steering automobile, the concrete steps of the method are as follows:

I) digital sampling and processing Real-time Collection chaufeur turns to intent information and vehicle condition parameter information, and turn to intent information and vehicle condition parameter information to carry out first treatment to the chaufeur gathered;

II) according to step I) chaufeur turn to intent information and vehicle condition parameter information, turn to pattern discrimination module to be the one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by the target diversion pattern discrimination of automobile under current state;

III) according to step I) chaufeur turn to intent information and vehicle condition parameter information, wheel steering angle computing module calculates the wheel steering angle numerical value under adjustment modes and the wheel steering angle numerical value under four-wheel pattern simultaneously;

IV) according to step II) and step III) result, the target diversion pattern of pattern Coordination module to automobile is turned to carry out coordination conversion, determine that the execution of automobile turns to pattern, calculate final wheel steering angle numerical value, and final wheel steering angle numerical value is passed to turns to execution module to perform.

Described step I) in digital sampling and processing respectively with turn to pattern discrimination module, wheel steering angle computing module and turn to execution module and be connected, described turn to pattern Coordination module to connect to turn to pattern discrimination module, wheel steering angle computing module and turn to execution module simultaneously;

Digital sampling and processing comprises acquisition module and processing module two parts;

Described acquisition module Real-time Collection chaufeur turns to intent information and vehicle condition parameter information; Described acquisition module comprises longitudinal car speed sensor, side direction car speed sensor, steering wheel angle sensor, gyroscope and wheel steering angle sensor; The chaufeur of acquisition module collection turns to intent information and vehicle condition parameter information to comprise turn signal state, actual wheel corner, steering wheel angle δ _sW, longitudinal vehicle velocity V _x, side direction vehicle velocity V _ywith yaw velocity ω _r;

Described processing module turns to the first treatment of intent information and vehicle condition parameter information to refer to carry out international unit conversion to the chaufeur gathered and calculates side slip angle β;

The computing formula of side slip angle β is: β=arctan (V _y/ V _x);

Wherein, V _xrepresent longitudinal speed of a motor vehicle, V _yrepresent the side direction speed of a motor vehicle;

Described step II) in, turn to pattern discrimination module according to the turn signal state of timely collection, longitudinal vehicle velocity V _x, longitudinal speed of a motor vehicle threshold value V _tx, steering wheel angle δ _sWwith steering wheel angle threshold value δ _tSWthe target diversion pattern discrimination of automobile is the one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by information, and result is sent to and turns to pattern Coordination module;

The described target diversion pattern discrimination by automobile is that the step of a kind of concrete differentiation in adjustment modes, four-wheel pattern, transition mode I or transition mode II is as follows:

101) judge whether automobile should be converted to four-wheel pattern, and concrete deterministic process is as follows:

If steering indicating light is opened, then think that motor turning pattern should be converted to four-wheel pattern; If steering indicating light is not opened, then longitudinal speed of a motor vehicle is judged;

If longitudinal speed of a motor vehicle is more than or equal to the threshold value of setting, i.e. V _x>=V _tx, then think that motor turning pattern should be converted to four-wheel pattern; If longitudinal speed of a motor vehicle is less than the threshold value of setting, i.e. V _x< V _tx, then steering wheel angle is judged;

If steering wheel angle is more than or equal to the threshold value of setting, i.e. δ _sW>=δ _tSW, then think that motor turning pattern should be converted to four-wheel pattern; If steering wheel angle is less than the threshold value of setting, i.e. δ _sW< δ _tSW, then think that motor turning pattern should be converted to adjustment modes;

102) setting-up time step is T _p, by step 101) current judged result and a upper time step judged result compare, make final judgement:

If current judged result is four-wheel pattern, a upper time step judged result is four-wheel pattern, then target diversion mode decision is four-wheel pattern;

If current judged result is four-wheel pattern, a upper time step judged result is adjustment modes, then target diversion mode decision is transition mode I;

If current judged result is adjustment modes, a upper time step judged result is four-wheel pattern, then target diversion mode decision is transition mode II;

If current judged result is adjustment modes, a upper time step judged result is adjustment modes, then target diversion mode decision is adjustment modes;

103) preserve step 101) current judged result;

104) target diversion pattern is exported.

Described step III) in, wheel steering angle computing module utilizes the chaufeur of digital sampling and processing acquisition process to turn to intent information and vehicle condition parameter information to calculate the wheel steering angle numerical value under adjustment modes and the wheel steering angle numerical value under four-wheel pattern, and result is sent to and turns to pattern Coordination module.Wheel steering angle computing module comprises adjustment modes wheel steering angle computing module and four-wheel pattern wheel steering angle computing module two parts.

Adjustment modes wheel steering angle computing module is according to the steering wheel angle δ of timely collection _sWcalculate the wheel steering angle numerical value under adjustment modes, concrete computation process is:

201) according to steering wheel angle δ _sWand the steering gear ratio i of setting, calculate front axle center effective rotation δ _f', described front axle center effective rotation δ _f' computing formula be: δ _f'=δ _sW/ i;

202) according to front axle center effective rotation δ _f', calculate inside and outside front wheel angle δ _if', δ _of', its computing formula is as follows:

$\left\{\begin{array}{cc}{{\mathrm{\&delta;}}_{if}}^{\&prime;}=arc\cot ({{\mathrm{cot\&delta;}}_f}^{\&prime;}-\frac{T_f}{2L}),{{\mathrm{\&delta;}}_{of}}^{\&prime;}=arc\cot ({{\mathrm{cot\&delta;}}_f}^{\&prime;}+\frac{T_f}{2L})& {{\mathrm{\&delta;}}_f}^{\&prime;}\&NotEqual;0\\ {{\mathrm{\&delta;}}_{if}}^{\&prime;}={{\mathrm{\&delta;}}_{of}}^{\&prime;}=0& {{\mathrm{\&delta;}}_f}^{\&prime;}=0\end{array}\right.---\left(1\right)$

Wherein, T _frepresent front wheel tread, L represents wheelbase;

203) (the i.e. δ if automobile turns left _sW>=0), now, front-wheel is the near front wheel, outer front-wheel is off front wheel, then make δ _fl'=δ _if', δ _fr'=δ _of'; (the i.e. δ if automobile is turned right _sW<0), now, front-wheel is off front wheel, outer front-wheel is the near front wheel, then make δ _fl'=δ _of', δ _fr'=δ _if';

Wherein, δ _fl' represent the near front wheel corner under adjustment modes, δ _fr' represent off front wheel corner under adjustment modes;

204) given two trailing wheel corner numerical value are 0, i.e. δ _rl'=δ _rr'=0;

Wherein, δ _rl' represent left rear wheel corner under adjustment modes, δ _rr' represent off hind wheel corner under adjustment modes;

205) the numerical value δ of lower four wheel steering angles of adjustment modes is exported _ij' (ij=fl, fr, rl, rr here, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel).

Four-wheel pattern wheel steering angle computing module is according to the steering wheel angle δ of timely collection _sW, longitudinal vehicle velocity V _x, side slip angle β, yaw velocity ω _rcalculate the wheel steering angle numerical value under four-wheel pattern, concrete computation process is:

301) according to steering wheel angle δ _sWand the steering gear ratio i of setting, computing reference front wheel angle the described computing formula with reference to front wheel angle is:

302) according to longitudinal vehicle velocity V _xwith reference front wheel angle calculate the desirable yaw velocity ω of automobile _rdwith desirable side slip angle β _d, computing formula is as follows:

$\left\{\begin{array}{c}{\mathrm{\&beta;}}_d=0\\ {\mathrm{\&omega;}}_{rd}=\frac{G_{\mathrm{\&omega;}}}{1+{\mathrm{\&tau;}}_{\mathrm{\&omega;}}s}\&CenterDot;{{\mathrm{\&delta;}}_f}^{*}\end{array}\right.---\left(2\right)$

And, | ω _rd|≤| 0.85 μ g/V _x|

Wherein, G _ωrepresent the steady-state gain of desirable yaw velocity, K represents the stability factor of vehicle, τ _ωrepresent inertial element time constant, μ represents coefficient of road adhesion, and g represents acceleration due to gravity, and a, b represent that automobile barycenter is to axle distance respectively, behalf Laplace operator;

303) side slip angle β and desirable side slip angle β is calculated _d, and yaw velocity ω _rwith desirable yaw velocity ω _rdbetween difference, obtain corresponding side slip angle error e _βwith yaw-rate error e _ω;

304) according to side slip angle error e _β, yaw-rate error e _ω, longitudinal vehicle velocity V _xwith reference front wheel angle model following optimal control law is utilized to calculate front and rear wheel corner base value δ _f, δ _r, model following optimal control law is as follows:

u＝-R ^-1B ^TPe-R ^-1B ^T(A ^T-PBR ^-1B ^T) ^-1PB _du _d

(3)

+R ^-1B ^T(A ^T-PBR ^-1B ^T) ^-1P(A-A _d)x _d

And, $u={\left[\begin{array}{cc}{\mathrm{\&delta;}}_F& {\mathrm{\&delta;}}_R\end{array}\right]}^T,A=\left[\begin{array}{cc}\frac{\left(2k_f+2k_r\right)}{{\mathrm{mV}}_x}& \frac{\left(2{\mathrm{ak}}_f-2{\mathrm{bk}}_r\right)}{{{\mathrm{mV}}_x}^2}-1\\ \frac{1}{I_z}\left(2{\mathrm{ak}}_f-2{\mathrm{bk}}_r\right)& \frac{1}{I_z{V}_x}\left(2a^2{k}_f+2b^2{k}_r\right)\end{array}\right],B=\left[\begin{array}{cc}-\frac{k_f}{{\mathrm{mV}}_x}& -\frac{k_r}{{\mathrm{mV}}_x}\\ -\frac{{\mathrm{ak}}_f}{I_Z}& \frac{{\mathrm{bk}}_r}{I_Z}\end{array}\right],$

$x_d={\left[\begin{array}{cc}{\mathrm{\&beta;}}_d& {\mathrm{\&omega;}}_{rd}\end{array}\right]}^T,u_d=\&lsqb;{\mathrm{\&delta;}}_f^{*}\&rsqb;,A_d=\left[\begin{array}{cc}0& 0\\ 0& -1/{\mathrm{\&tau;}}_{\mathrm{\&omega;}}\end{array}\right],B_d=\left[\begin{array}{c}0\\ G_{\mathrm{\&omega;}}/{\mathrm{\&tau;}}_{\mathrm{\&omega;}}\end{array}\right],e=\left[\begin{array}{c}{e}_{\mathrm{\&beta;}}\\ e_{\mathrm{\&omega;}}\end{array}\right];$

Wherein, I _zrepresent the yaw rotation inertia of automobile, k _f, k _rrepresent front and rear wheel cornering stiffness, m represents complete vehicle quality, and P is Riccati equation PA+Q+A ^tp-PBR ^-1b ^tthe solution of P=0, Q is controling parameters.R is controling parameters.

305) wheel steering angle increment Δ δ is calculated _f1, Δ δ _f2, Δ δ _r1, Δ δ _r2, its formula is as follows:

$\left\{\begin{array}{c}{\mathrm{\&Delta;\&delta;}}_{F1}=f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_F),{\mathrm{\&Delta;\&delta;}}_{F2}=2\&CenterDot;f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_F)\\ {\mathrm{\&Delta;\&delta;}}_{R1}=f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_R),{\mathrm{\&Delta;\&delta;}}_{R2}=2\&CenterDot;f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_R)\end{array}\right.---\left(4\right)$

And, $f\left(\right|e_{\mathrm{\&omega;}}\left|\right)=\left\{\begin{array}{cc}0& 0\&le;\left|e_{\mathrm{\&omega;}}\right|<0.01\\ \frac{100\left|e_{\mathrm{\&omega;}}\right|-1}{9}& 0.01\&le;\left|e_{\mathrm{\&omega;}}\right|<0.1\\ 1& \left|e_{\mathrm{\&omega;}}\right|\&GreaterEqual;0.1\end{array}\right.$

Wherein, k represents wheel steering angle value-added coefficient, its value (0,0.25] between.

306) utilize with reference to front wheel angle longitudinal vehicle velocity V _x, longitudinal speed of a motor vehicle threshold value V _txwith yaw-rate error e _ω, motion state of automobile is judged; According to different motion state of automobile, utilize wheel steering angle base value δ _f, δ _rwith increment Δ δ _f1, Δ δ _f2, Δ δ _r, ₁Δ δ _r2, with reasonable distribution side force of tire for target, calculate four-wheel pattern wheel steering angle, specific as follows:

When time, judge that automobile is in high speed, left-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in high speed, left-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in high speed, right-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

When time, judge that automobile is in high speed, right-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

When time, judge that automobile is in low speed, left-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in low speed, left-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in low speed, right-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

When time, judge that automobile is in low speed, right-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

Wherein, δ _flrepresent the near front wheel corner under four-wheel pattern, δ _frrepresent the off front wheel corner under four-wheel pattern, δ _rlrepresent the left rear wheel corner under four-wheel pattern, δ _rrrepresent the off hind wheel corner under four-wheel pattern;

307) the numerical value δ of lower four wheel steering angles of four-wheel pattern is exported _ij(ij=fl, fr, rl, rr here, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel).

Described step IV) in, according to the wheel steering angle numerical value δ under the target diversion pattern of automobile, adjustment modes _ij' and the lower wheel steering angle numerical value δ of four-wheel pattern _ij, turn to the target diversion pattern of pattern Coordination module to automobile to carry out coordination conversion, determine that the execution of automobile turns to pattern, calculate final wheel steering angle and result of calculation is sent to and turn to execution module.

Describedly determine that the execution of automobile turns to pattern and to calculate final wheel steering angle concrete steps as follows:

401) by reading timer internal working mark, judge whether the front steering pattern of automobile is transition mode and this transition mode does not complete;

402) if timer internal works, now do not allow to carry out turning to patten transformation, the front steering pattern of reading and saving and timer running time T also turn to pattern with front steering pattern for performing, and calculate final wheel steering angle numerical value according to corresponding calculative strategy;

403) if timer internal does not work, now allow to carry out turning to patten transformation, target diversion pattern information differentiated:

When target diversion pattern is transition mode I, starts timer and also preserve transition mode I for front steering pattern, system for execution turns to pattern, and calculates final wheel steering angle final_ δ according to the corresponding strategy of transition mode I with transition mode I _ij, its corresponding calculative strategy is:

$final\_{\mathrm{\&delta;}}_{ij}=(1-\frac{T}{T_{total}}){\mathrm{\&delta;}}_{ij}+\frac{T}{T_{total}}{{\mathrm{\&delta;}}_{ij}}^{\&prime;}---\left(5\right)$

Wherein, T represents timer time of run; T _totalrepresent the total duration of transition mode of timer setting, T _totalvalue with turn to the time step T set in pattern discrimination module _punanimously;

When target diversion pattern is transition mode II, starts timer and also preserve transition mode II for front steering pattern, system for execution turns to pattern, and calculates final wheel steering angle final_ δ according to the corresponding strategy of transition mode II with transition mode II _ij, its corresponding calculative strategy is:

$final\_{\mathrm{\&delta;}}_{ij}=\frac{T}{T_{total}}{\mathrm{\&delta;}}_{ij}+(1-\frac{T}{T_{total}}){{\mathrm{\&delta;}}_{ij}}^{\&prime;}---\left(6\right)$

When target diversion pattern is four-wheel pattern, system turns to pattern with four-wheel pattern for performing, and calculates final wheel steering angle final_ δ according to the corresponding strategy of four-wheel pattern _ij, its corresponding calculative strategy is:

final_δ _ij＝δ _ij(7)

When target diversion pattern is adjustment modes, system is perform to turn to pattern with adjustment modes, and calculates final wheel steering angle final_ δ according to the corresponding strategy of adjustment modes _ij, its corresponding calculative strategy is:

final_δ _ij＝δ _ij' (8)

404) final wheel steering angle value final_ δ is exported _ij(ij=fl, fr, rl, rr here, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel).

Described step IV) in turn to execution module, the final wheel steering angle calculated according to turning to pattern Coordination module and the actual wheel corner of digital sampling and processing timely collection, produce corresponding control command, realize Vehicular turn.

Compared with prior art, the present invention has the following advantages:

Instant invention overcomes some shortcomings in existing four-wheel steering technology, for four-wheel independent steering automobile provides a kind of actv. rotating direction control method.

The present invention can turn to intention and vehicle condition information to be one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by the pattern discrimination that turns to of automobile according to chaufeur, and according to respectively turning to the corresponding strategy calculating wheel steering angle of pattern.Wherein, what conversion between adjustment modes and four-wheel pattern reduced automobile of knowing clearly turns to energy ezpenditure, and the existence of transition mode I and transition mode II then ensure that and seamlessly transits between adjustment modes and four-wheel pattern.

Four-wheel pattern wheel steering angle method of calculating in the present invention, side slip angle can not only be met and yaw velocity two mainly turns to index simultaneously, the reasonable distribution greatly can also improving side force of tire utilizes, and realizes the further raising of four-wheel independent steering stability of automobile and steering safety.

Accompanying drawing explanation

Accompanying drawing 1 is control method schematic flow sheet of the present invention;

Accompanying drawing 2 is target diversion pattern discrimination diagram of circuits;

Accompanying drawing 3 is adjustment modes wheel steering angle calculation flow charts;

Accompanying drawing 4 is four-wheel pattern wheel steering angle calculation flow charts;

Accompanying drawing 5 turns to pattern to coordinate diagram of circuit.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.The present embodiment is implemented premised on technical solution of the present invention, give detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

As shown in Figure 1, the rotating direction control method of four-wheel independent steering automobile that the embodiment of the present invention provides comprises the steps:

I) digital sampling and processing Real-time Collection chaufeur turns to intent information and vehicle condition parameter information, and turn to intent information and vehicle condition parameter information to carry out first treatment to the chaufeur gathered;

II) according to step I) chaufeur turn to intent information and vehicle condition parameter information, turn to pattern discrimination module to be the one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by the target diversion pattern discrimination of automobile under current state;

III) according to step I) chaufeur turn to intent information and vehicle condition parameter information, wheel steering angle computing module calculates the wheel steering angle numerical value under adjustment modes and the wheel steering angle numerical value under four-wheel pattern simultaneously;

IV) according to step II) and step III) result, the target diversion pattern of pattern Coordination module to automobile is turned to carry out coordination conversion, determine that the execution of automobile turns to pattern, calculate final wheel steering angle numerical value, and final wheel steering angle numerical value is passed to turns to execution module to perform.

Described step I) in digital sampling and processing respectively with turn to pattern discrimination module, wheel steering angle computing module and turn to execution module and be connected, described turn to pattern Coordination module to connect to turn to pattern discrimination module, wheel steering angle computing module and turn to execution module simultaneously;

Digital sampling and processing comprises acquisition module and processing module two parts;

Described acquisition module Real-time Collection chaufeur turns to intent information and vehicle condition parameter information; Described acquisition module comprises longitudinal car speed sensor, side direction car speed sensor, steering wheel angle sensor, gyroscope and wheel steering angle sensor; The chaufeur of acquisition module collection turns to intent information and vehicle condition parameter information to comprise turn signal state, actual wheel corner, steering wheel angle δ _sW, longitudinal vehicle velocity V _x, side direction vehicle velocity V _ywith yaw velocity ω _r;

Described processing module turns to the first treatment of intent information and vehicle condition parameter information to refer to carry out international unit conversion to the chaufeur gathered and calculates side slip angle β;

The computing formula of side slip angle β is: β=arctan (V _y/ V _x);

Wherein, V _xrepresent longitudinal speed of a motor vehicle, V _yrepresent the side direction speed of a motor vehicle;

Described step II) in, turn to pattern discrimination module according to the turn signal state of timely collection, longitudinal vehicle velocity V _x, longitudinal speed of a motor vehicle threshold value V _tx, steering wheel angle δ _sWwith steering wheel angle threshold value δ _tSWthe target diversion pattern discrimination of automobile is the one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by information, and result is sent to and turns to pattern Coordination module;

The step by the target diversion pattern discrimination of automobile being a kind of concrete differentiation in adjustment modes, four-wheel pattern, transition mode I or transition mode II is as follows:

101) determine four-wheel mode flags position, detailed process is as follows:

If steering indicating light is opened, then four-wheel mode flags position 1; If steering indicating light is not opened, then longitudinal speed of a motor vehicle is judged;

Set longitudinal speed of a motor vehicle threshold value V _txfor 10m/s, if longitudinal vehicle velocity V _x>=10m/s, then four-wheel mode flags position 1; If longitudinal vehicle velocity V _x< 10m/s, then judge steering wheel angle;

Direction initialization dish corner threshold value is 0.17rad, if steering wheel angle δ _sW>=0.17rad, then four-wheel mode flags position 1; If steering wheel angle δ _sW< 0.17rad, then four-wheel mode flags position 0;

102) by step 101) four-wheel mode flags position and the front four-wheel mode flags position of preservation (namely go up the four-wheel mode flags position of a time step, time step T in example _pfor 200ms) compare, differentiate that vehicle target turns to pattern:

If four-wheel mode flags position is 1, front four-wheel mode flags position is 1, then target diversion mode decision is four-wheel pattern;

If four-wheel mode flags position is 1, front four-wheel mode flags position is 0, then target diversion mode decision is transition mode I;

If four-wheel mode flags position is 0, front four-wheel mode flags position is 1, then target diversion mode decision is transition mode II;

If four-wheel mode flags position is 0, front four-wheel mode flags position is 0, then target diversion mode decision is adjustment modes;

103) four-wheel mode flags position before upgrading;

104) target diversion pattern is exported.

Described step III) in, wheel steering angle computing module utilizes the chaufeur of digital sampling and processing acquisition process to turn to intent information and vehicle condition parameter information to calculate the wheel steering angle numerical value under adjustment modes and the wheel steering angle numerical value under four-wheel pattern, and result is sent to and turns to pattern Coordination module.Wheel steering angle computing module comprises adjustment modes wheel steering angle computing module and four-wheel pattern wheel steering angle computing module two parts.

As shown in Figure 3, adjustment modes wheel steering angle computing module is according to the steering wheel angle δ of timely collection _sWcalculate the wheel steering angle numerical value under adjustment modes, concrete computation process is:

201) according to steering wheel angle δ _sWand the steering gear ratio i of setting, calculate front axle center effective rotation δ _f', described front axle center effective rotation δ _f' computing formula be: δ _f'=δ _sWi;

202) according to front axle center effective rotation δ _f', calculate inside and outside front wheel angle δ _if', δ _of', its computing formula is as follows:

$\left\{\begin{array}{cc}{{\mathrm{\&delta;}}_{if}}^{\&prime;}=arc\cot ({{\mathrm{cot\&delta;}}_f}^{\&prime;}-\frac{T_f}{2L}),{{\mathrm{\&delta;}}_{of}}^{\&prime;}=arc\cot ({{\mathrm{cot\&delta;}}_f}^{\&prime;}+\frac{T_f}{2L})& {{\mathrm{\&delta;}}_f}^{\&prime;}\&NotEqual;0\\ {{\mathrm{\&delta;}}_{if}}^{\&prime;}={{\mathrm{\&delta;}}_{of}}^{\&prime;}=0& {{\mathrm{\&delta;}}_f}^{\&prime;}=0\end{array}\right.---\left(1\right)$

Wherein, T _frepresent front wheel tread, L represents wheelbase;

203) (the i.e. δ if automobile turns left _sW>=0), now, front-wheel is the near front wheel, outer front-wheel is off front wheel, then make δ _fl'=δ _if', δ _fr'=δ _of'; (the i.e. δ if automobile is turned right _sW<0), now, front-wheel is off front wheel, outer front-wheel is the near front wheel, then make δ _fl'=δ _of', δ _fr'=δ _if';

Wherein, δ _fl' represent the near front wheel corner under adjustment modes, δ _fr' represent off front wheel corner under adjustment modes;

204) given two trailing wheel corner numerical value are 0, i.e. δ _rl'=δ _rr'=0;

Wherein, δ _rl' represent left rear wheel corner under adjustment modes, δ _rr' represent off hind wheel corner under adjustment modes;

205) the numerical value δ of lower four wheel steering angles of adjustment modes is exported _ij' (ij=fl, fr, rl, rr here, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel).

As shown in Figure 4, four-wheel pattern wheel steering angle computing module is according to the steering wheel angle δ of timely collection _sW, longitudinal vehicle velocity V _x, side slip angle β, yaw velocity ω _rcalculate the wheel steering angle numerical value under four-wheel pattern, concrete computation process is:

301) according to steering wheel angle δ _sWand the steering gear ratio i of setting, computing reference front wheel angle the described computing formula with reference to front wheel angle is:

302) according to longitudinal vehicle velocity V _xwith reference front wheel angle calculate the desirable yaw velocity ω of automobile _rdwith desirable side slip angle β _d, computing formula is as follows:

$\left\{\begin{array}{c}{\mathrm{\&beta;}}_d=0\\ {\mathrm{\&omega;}}_{rd}=\frac{G_{\mathrm{\&omega;}}}{1+{\mathrm{\&tau;}}_{\mathrm{\&omega;}}s}\&CenterDot;{{\mathrm{\&delta;}}_f}^{*}\end{array}\right.---\left(2\right)$

And, | ω _rd|≤| 0.85 μ g/V _x|

Wherein, G _ωrepresent the steady-state gain of desirable yaw velocity, K represents the stability factor of vehicle, τ _ωrepresent inertial element time constant, μ represents coefficient of road adhesion, and g represents acceleration due to gravity, and a, b represent that automobile barycenter is to axle distance respectively, behalf Laplace operator;

303) side slip angle β and desirable side slip angle β is calculated _d, and yaw velocity ω _rwith desirable yaw velocity ω _rdbetween difference, obtain corresponding side slip angle error e _βwith yaw-rate error e _ω;

304) according to side slip angle error e _β, yaw-rate error e _ω, longitudinal vehicle velocity V _xwith reference front wheel angle model following optimal control law is utilized to calculate front and rear wheel corner base value δ _f, δ _r, model following optimal control law is as follows:

u＝-R ^-1B ^TPe-R ^-1B ^T(A ^T-PBR ^-1B ^T) ^-1PB _du _d

(3)

+R ^-1B ^T(A ^T-PBR ^-1B ^T) ^-1P(A-A _d)x _d

And, $u={\left[\begin{array}{cc}{\mathrm{\&delta;}}_F& {\mathrm{\&delta;}}_R\end{array}\right]}^T,A=\left[\begin{array}{cc}\frac{\left(2k_f+2k_r\right)}{{\mathrm{mV}}_x}& \frac{\left(2{\mathrm{ak}}_f-2{\mathrm{bk}}_r\right)}{{{\mathrm{mV}}_x}^2}-1\\ \frac{1}{I_z}\left(2{\mathrm{ak}}_f-2{\mathrm{bk}}_r\right)& \frac{1}{I_z{V}_x}\left(2a^2{k}_f+2b^2{k}_r\right)\end{array}\right],B=\left[\begin{array}{cc}-\frac{k_f}{{\mathrm{mV}}_x}& -\frac{k_r}{{\mathrm{mV}}_x}\\ -\frac{{\mathrm{ak}}_f}{I_Z}& \frac{{\mathrm{bk}}_r}{I_Z}\end{array}\right],$

$x_d={\left[\begin{array}{cc}{\mathrm{\&beta;}}_d& {\mathrm{\&omega;}}_{rd}\end{array}\right]}^T,u_d=\&lsqb;{\mathrm{\&delta;}}_f^{*}\&rsqb;,A_d=\left[\begin{array}{cc}0& 0\\ 0& -1/{\mathrm{\&tau;}}_{\mathrm{\&omega;}}\end{array}\right],B_d=\left[\begin{array}{c}0\\ G_{\mathrm{\&omega;}}/{\mathrm{\&tau;}}_{\mathrm{\&omega;}}\end{array}\right],e=\left[\begin{array}{c}{e}_{\mathrm{\&beta;}}\\ e_{\mathrm{\&omega;}}\end{array}\right];$

Wherein, I _zrepresent the yaw rotation inertia of automobile, k _f, k _rrepresent front and rear wheel cornering stiffness, m represents complete vehicle quality, and P is Riccati equation PA+Q+A ^tp-PBR ^-1b ^tthe solution of P=0, Q is controling parameters.R is controling parameters.

305) wheel steering angle increment Δ δ is calculated _f1, Δ δ _f2, Δ δ _r1, Δ δ _r2, its formula is as follows:

$\left\{\begin{array}{c}{\mathrm{\&Delta;\&delta;}}_{F1}=f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_F),{\mathrm{\&Delta;\&delta;}}_{F2}=2\&CenterDot;f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_F)\\ {\mathrm{\&Delta;\&delta;}}_{R1}=f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_R),{\mathrm{\&Delta;\&delta;}}_{R2}=2\&CenterDot;f\left(\right|e_{\mathrm{\&omega;}}\left|\right)\&CenterDot;(k\&CenterDot;{\mathrm{\&delta;}}_R)\end{array}\right.---\left(4\right)$

And, $f\left(\right|e_{\mathrm{\&omega;}}\left|\right)=\left\{\begin{array}{cc}0& 0\&le;\left|e_{\mathrm{\&omega;}}\right|<0.01\\ \frac{100\left|e_{\mathrm{\&omega;}}\right|-1}{9}& 0.01\&le;\left|e_{\mathrm{\&omega;}}\right|<0.1\\ 1& \left|e_{\mathrm{\&omega;}}\right|\&GreaterEqual;0.1\end{array}\right.$

Wherein, k represents wheel steering angle value-added coefficient, is taken as 0.2 in embodiment.

306) utilize with reference to front wheel angle longitudinal vehicle velocity V _x, longitudinal speed of a motor vehicle threshold value V _txwith yaw-rate error e _ω, motion state of automobile is judged; According to different motion state of automobile, utilize wheel steering angle base value δ _f, δ _rwith increment Δ δ _f1, Δ δ _f2, Δ δ _r, ₁Δ δ _r2, with reasonable distribution side force of tire for target, calculate four-wheel pattern wheel steering angle, specific as follows:

Longitudinal speed of a motor vehicle threshold value V _txbe set as 10m/s;

When time, judge that automobile is in high speed, left-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in high speed, left-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in high speed, right-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

When time, judge that automobile is in high speed, right-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

When time, judge that automobile is in low speed, left-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in low speed, left-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2}\end{array}\right.;$

When time, judge that automobile is in low speed, right-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F-\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R-{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

When time, judge that automobile is in low speed, right-hand rotation, understeering state, the wheel steering angle calculative strategy taked is: $\left\{\begin{array}{c}{\mathrm{\&delta;}}_{fl}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F2},{\mathrm{\&delta;}}_{fr}={\mathrm{\&delta;}}_F+\mathrm{\&Delta;}{\mathrm{\&delta;}}_{F1}\\ {\mathrm{\&delta;}}_{rl}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R2},{\mathrm{\&delta;}}_{rr}={\mathrm{\&delta;}}_R+{\mathrm{\&Delta;\&delta;}}_{R1}\end{array}\right.;$

Wherein, δ _flrepresent the near front wheel corner under four-wheel pattern, δ _frrepresent the off front wheel corner under four-wheel pattern, δ _rlrepresent the left rear wheel corner under four-wheel pattern, δ _rrrepresent the off hind wheel corner under four-wheel pattern;

307) the numerical value δ of lower four wheel steering angles of four-wheel pattern is exported _ij(ij=fl, fr, rl, rr here, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel).

Described step IV) in, according to the wheel steering angle numerical value δ under the target diversion pattern of automobile, adjustment modes _ij' and the lower wheel steering angle numerical value δ of four-wheel pattern _ij, turn to the target diversion pattern of pattern Coordination module to automobile to carry out coordination conversion, determine that the execution of automobile turns to pattern, calculate final wheel steering angle and result of calculation is sent to and turn to execution module.

As shown in Figure 5, describedly determine that the execution of automobile turns to pattern and to calculate final wheel steering angle concrete steps as follows:

401) by reading timer internal working mark position, judge whether the front steering pattern of automobile is transition mode and this transition mode does not complete;

402) if timer internal working mark position is 1, now do not allow to carry out turning to patten transformation, the front steering pattern of reading and saving and timer running time T also turn to pattern with front steering pattern for performing, and calculate final wheel steering angle numerical value according to corresponding calculative strategy;

403) if timer internal working mark position is 0, now allow to carry out turning to patten transformation, target diversion pattern information differentiated:

When target diversion pattern is transition mode I, starts timer and also preserve transition mode I for front steering pattern, system for execution turns to pattern, and calculates final wheel steering angle final_ δ according to the corresponding strategy of transition mode I with transition mode I _ij, its corresponding calculative strategy is:

$final\_{\mathrm{\&delta;}}_{ij}=(1-\frac{T}{T_{total}}){\mathrm{\&delta;}}_{ij}+\frac{T}{T_{total}}{{\mathrm{\&delta;}}_{ij}}^{\&prime;}---\left(5\right)$

Wherein, T represents timer time of run; T _totalrepresent the total duration of transition mode of timer setting, T _totalvalue with turn to the time step T set in pattern discrimination module _punanimously, 200ms is taken as in example;

When target diversion pattern is transition mode II, starts timer and also preserve transition mode II for front steering pattern, system for execution turns to pattern, and calculates final wheel steering angle final_ δ according to the corresponding strategy of transition mode II with transition mode II _ij, its corresponding calculative strategy is:

$final\_{\mathrm{\&delta;}}_{ij}=\frac{T}{T_{total}}{\mathrm{\&delta;}}_{ij}+(1-\frac{T}{T_{total}}){{\mathrm{\&delta;}}_{ij}}^{\&prime;}---\left(6\right)$

When target diversion pattern is four-wheel pattern, system turns to pattern with four-wheel pattern for performing, and calculates final wheel steering angle final_ δ according to the corresponding strategy of four-wheel pattern _ij, its corresponding calculative strategy is:

final_δ _ij＝δ _ij(7)

When target diversion pattern is adjustment modes, system is perform to turn to pattern with adjustment modes, and calculates final wheel steering angle final_ δ according to the corresponding strategy of adjustment modes _ij, its corresponding calculative strategy is:

final_δ _ij＝δ _ij' (8)

404) final wheel steering angle value final_ δ is exported _ij(ij=fl, fr, rl, rr here, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel).

Described step IV) in, the final wheel steering angle turning to execution module simultaneously to receive to turn to pattern Coordination module to calculate and the actual wheel corner of digital sampling and processing timely collection, and utilize the difference between final wheel steering angle and actual wheel corner to produce corresponding control command, realize turning to of vehicle.

This example provides a kind of rotating direction control method of four-wheel independent steering automobile.According to the rotating direction control method that this example provides, can overcome active rear steer technology improve motor turning stability limited and initiatively four-wheel steering technology do not consider the shortcoming of analysis of wheel vertical load transfer, realize the road-holding property and the steering safety that further improve automobile while four-wheel independence motor turning controls, improve side force of tire degree of utilization, also reduce the ability consumption turned to a certain extent.

The invention is not restricted to above-mentioned example, can various change be carried out.

Claims (10)

1. a rotating direction control method for four-wheel independent steering automobile, is characterized in that, comprises the steps:

I) digital sampling and processing Real-time Collection chaufeur turns to intent information and vehicle condition parameter information, and turn to intent information and vehicle condition parameter information to carry out first treatment to the chaufeur gathered;

II) according to step I) chaufeur turn to intent information and vehicle condition parameter information, turn to pattern discrimination module to be the one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by the target diversion pattern discrimination of automobile under current state;

III) according to step I) chaufeur turn to intent information and vehicle condition parameter information, wheel steering angle computing module calculates the wheel steering angle numerical value under adjustment modes and the wheel steering angle numerical value under four-wheel pattern simultaneously;

IV) according to step II) and step III) result, the target diversion pattern of pattern Coordination module to automobile is turned to carry out coordination conversion, determine that the execution of automobile turns to pattern, calculate final wheel steering angle numerical value, and final wheel steering angle numerical value is passed to turns to execution module to perform.

2. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 1, is characterized in that:

Described step I) in digital sampling and processing respectively with turn to pattern discrimination module, wheel steering angle computing module and turn to execution module and be connected, described turn to pattern Coordination module to connect to turn to pattern discrimination module, wheel steering angle computing module and turn to execution module simultaneously;

Digital sampling and processing comprises acquisition module and processing module two parts;

Described acquisition module Real-time Collection chaufeur turns to intent information and vehicle condition parameter information; Described acquisition module comprises longitudinal car speed sensor, side direction car speed sensor, steering wheel angle sensor, gyroscope and wheel steering angle sensor; The chaufeur of acquisition module collection turns to intent information and vehicle condition parameter information to comprise turn signal state, actual wheel corner, steering wheel angle δ _sW, longitudinal vehicle velocity V _x, side direction vehicle velocity V _ywith yaw velocity ω _r;

Described processing module turns to the first treatment of intent information and vehicle condition parameter information to refer to carry out international unit conversion to the chaufeur gathered and calculates side slip angle β;

The computing formula of side slip angle β is: β=arctan (V _y/ V _x);

Wherein, V _xrepresent longitudinal speed of a motor vehicle, V _yrepresent the side direction speed of a motor vehicle.

3. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 1, is characterized in that:

Described step II) in, turn to pattern discrimination module according to the turn signal state of timely collection, longitudinal vehicle velocity V _x, longitudinal speed of a motor vehicle threshold value V _tx, steering wheel angle δ _sWwith steering wheel angle threshold value δ _tSWthe target diversion pattern discrimination of automobile is the one in adjustment modes, four-wheel pattern, transition mode I or transition mode II by information, and result is sent to and turns to pattern Coordination module.

4. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 3, is characterized in that:

The described target diversion pattern discrimination by automobile is that the step of a kind of concrete differentiation in adjustment modes, four-wheel pattern, transition mode I or transition mode II is as follows:

101) judge whether automobile should be converted to four-wheel pattern, and concrete deterministic process is as follows:

If steering indicating light is opened, then think that motor turning pattern should be converted to four-wheel pattern; If steering indicating light is not opened, then longitudinal speed of a motor vehicle is judged;

If longitudinal speed of a motor vehicle is more than or equal to the threshold value of setting, then think that motor turning pattern should be converted to four-wheel pattern; If longitudinal speed of a motor vehicle is less than the threshold value of setting, then steering wheel angle is judged;

If steering wheel angle is more than or equal to the threshold value of setting, then think that motor turning pattern should be converted to four-wheel pattern; If steering wheel angle is less than the threshold value of setting, then think that motor turning pattern should be converted to adjustment modes;

102) setting-up time step is T _p, by step 101) current judged result and a upper time step judged result compare, make final judgement:

If current judged result is four-wheel pattern, a upper time step judged result is four-wheel pattern, then target diversion mode decision is four-wheel pattern;

If current judged result is four-wheel pattern, a upper time step judged result is adjustment modes, then target diversion mode decision is transition mode I;

If current judged result is adjustment modes, a upper time step judged result is four-wheel pattern, then target diversion mode decision is transition mode II;

If current judged result is adjustment modes, a upper time step judged result is adjustment modes, then target diversion mode decision is adjustment modes;

103) preserve step 101) current judged result;

104) target diversion pattern is exported.

5. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 1, is characterized in that:

Described step III) in, wheel steering angle computing module utilizes the chaufeur of digital sampling and processing acquisition process to turn to intent information and vehicle condition parameter information to calculate the wheel steering angle numerical value under adjustment modes and the wheel steering angle numerical value under four-wheel pattern, and result is sent to and turns to pattern Coordination module;

Described wheel steering angle computing module comprises adjustment modes wheel steering angle computing module and four-wheel pattern wheel steering angle computing module two parts;

Described adjustment modes wheel steering angle computing module is according to the steering wheel angle δ of timely collection _sW, calculate the wheel steering angle numerical value under adjustment modes;

Described four-wheel pattern wheel steering angle computing module is according to the steering wheel angle δ of timely collection _sW, longitudinal vehicle velocity V _x, side slip angle β and yaw velocity ω _r, calculate the wheel steering angle numerical value under four-wheel pattern.

6. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 5, is characterized in that:

The concrete computation process of the wheel steering angle numerical value under described calculating adjustment modes is:

201) according to steering wheel angle δ _sWand the steering gear ratio i of setting, calculate front axle center effective rotation δ _f', described front axle center effective rotation δ _f' computing formula be: δ _f'=δ _sW/ i;

202) according to front axle center effective rotation δ _f', calculate inside and outside front wheel angle δ _if', δ _of', its computing formula is as follows:

Wherein, T _frepresent front wheel tread, L represents wheelbase;

203) if automobile turns left, now, front-wheel is the near front wheel, outer front-wheel is off front wheel, then make δ _fl'=δ _if', δ _fr'=δ _of'; If automobile is turned right, now, front-wheel is off front wheel, outer front-wheel is the near front wheel, then make δ _fl'=δ _of', δ _fr'=δ _if';

Wherein, δ _fl' represent the near front wheel corner under adjustment modes, δ _fr' represent off front wheel corner under adjustment modes;

204) given two trailing wheel corner numerical value are 0, particularly, and order: δ _rl'=δ _rr'=0;

Wherein, δ _rl' represent left rear wheel corner under adjustment modes, δ _rr' represent off hind wheel corner under adjustment modes;

205) the numerical value δ of lower four wheel steering angles of adjustment modes is exported _ij'; Here ij=fl, fr, rl, rr, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel.

7. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 5, is characterized in that:

The concrete computation process of the wheel steering angle numerical value under described calculating four-wheel pattern is:

301) according to steering wheel angle δ _sWand the steering gear ratio i of setting, computing reference front wheel angle the described computing formula with reference to front wheel angle is:

302) according to longitudinal vehicle velocity V _xwith reference front wheel angle calculate the desirable yaw velocity ω of automobile _rdwith desirable side slip angle β _d, computing formula is as follows:

And, | ω _rd|≤| 0.85 μ g/V _x|

Wherein, G _ωrepresent the steady-state gain of desirable yaw velocity;

K represents the stability factor of vehicle;

τ _ωrepresent inertial element time constant;

μ represents coefficient of road adhesion;

G represents acceleration due to gravity;

A, b represent that automobile barycenter is to axle distance respectively;

Behalf Laplace operator;

303) side slip angle β and desirable side slip angle β is calculated _d, and yaw velocity ω _rwith desirable yaw velocity ω _rdbetween difference, obtain corresponding side slip angle error e _βwith yaw-rate error e _ω;

304) according to side slip angle error e _β, yaw-rate error e _ω, longitudinal vehicle velocity V _xwith reference front wheel angle model following optimal control law is utilized to calculate front and rear wheel corner base value δ _f, δ _r, model following optimal control law is as follows:

u＝-R ^-1B ^TPe-R ^-1B ^T(A ^T-PBR ^-1B ^T) ^-1PB _du _d(3)

+R ^-1B ^T(A ^T-PBR ^-1B ^T) ^-1P(A-A _d)x _d

And, u=[δ _fδ _r] ^t,

x _d＝[β _dω _rd] ^T，

Wherein, I _zrepresent the yaw rotation inertia of automobile;

K _f, k _rrepresent front and rear wheel cornering stiffness;

M represents complete vehicle quality;

P is Riccati equation PA+Q+A ^tp-PBR ^-1b ^tthe solution of P=0;

Q is controling parameters;

R is controling parameters;

305) wheel steering angle increment Δ δ is calculated _f1, Δ δ _f2, Δ δ _r1, Δ δ _r2, its formula is as follows:

And,

Wherein, k represents wheel steering angle value-added coefficient, its value (0,0.25] between;

306) utilize with reference to front wheel angle longitudinal vehicle velocity V _x, longitudinal speed of a motor vehicle threshold value V _txwith yaw-rate error e _ω, motion state of automobile is judged; According to different motion state of automobile, utilize wheel steering angle base value δ _f, δ _rwith increment Δ δ _f1, Δ δ _f2, Δ δ _r1, Δ δ _r, with reasonable distribution side force of tire for target, calculate four-wheel pattern wheel steering angle, specific as follows:

Work as V _x>=V _tx, e _ωduring < 0, judge that automobile is in high speed, left-hand rotation, understeering state, the wheel steering angle calculative strategy taked is:

Work as V _x>=V _tx, e _ωwhen>=0, judge that automobile is in high speed, left-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is:

Work as V _x>=V _tx, e _ωduring < 0, judge that automobile is in high speed, right-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is:

Work as V _x>=V _tx, e _ωwhen>=0, judge that automobile is in high speed, right-hand rotation, understeering state, the wheel steering angle calculative strategy taked is:

Work as V _x< V _tx, e _ωduring < 0, judge that automobile is in low speed, left-hand rotation, understeering state, the wheel steering angle calculative strategy taked is:

Work as V _x< V _tx, e _ωwhen>=0, judge that automobile is in low speed, left-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is:

Work as V _x< V _tx, e _ωduring < 0, judge that automobile is in low speed, right-hand rotation, oversteer state, the wheel steering angle calculative strategy taked is:

Work as V _x< V _tx, e _ωwhen>=0, judge that automobile is in low speed, right-hand rotation, understeering state, the wheel steering angle calculative strategy taked is:

Wherein, δ _flrepresent the near front wheel corner under four-wheel pattern, δ _frrepresent the off front wheel corner under four-wheel pattern, δ _rlrepresent the left rear wheel corner under four-wheel pattern, δ _rrrepresent the off hind wheel corner under four-wheel pattern;

307) the numerical value δ of lower four wheel steering angles of four-wheel pattern is exported _ij; Here ij=fl, fr, rl, rr, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel.

8. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 1, is characterized in that:

Described step IV) in, according to the wheel steering angle numerical value δ under the target diversion pattern of automobile, adjustment modes _ij' and the lower wheel steering angle numerical value δ of four-wheel pattern _ij, turn to the target diversion pattern of pattern Coordination module to automobile to carry out coordination conversion, determine that the execution of automobile turns to pattern, calculate final wheel steering angle and result of calculation is sent to and turn to execution module.

9. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 8, is characterized in that:

Describedly determine that the execution of automobile turns to pattern and to calculate final wheel steering angle concrete steps as follows:

401) by reading timer internal working mark, judge whether the front steering pattern of automobile is transition mode and this transition mode does not complete;

402) if timer internal works, now do not allow to carry out turning to patten transformation, the front steering pattern of reading and saving and timer running time T also turn to pattern with front steering pattern for performing, and calculate final wheel steering angle numerical value according to corresponding calculative strategy;

403) if timer internal does not work, now allow to carry out turning to patten transformation, target diversion pattern information differentiated:

When target diversion pattern is transition mode I, starts timer and also preserve transition mode I for front steering pattern, system for execution turns to pattern, and calculates final wheel steering angle final_ δ according to the corresponding strategy of transition mode I with transition mode I _ij, its corresponding calculative strategy is:

Wherein, T represents timer time of run;

T _totalrepresent the total duration of transition mode of timer setting, T _totalvalue with turn to the time step T set in pattern discrimination module _punanimously;

When target diversion pattern is transition mode II, starts timer and also preserve transition mode II for front steering pattern, system for execution turns to pattern, and calculates final wheel steering angle final_ δ according to the corresponding strategy of transition mode II with transition mode II _ij, its corresponding calculative strategy is:

When target diversion pattern is four-wheel pattern, system turns to pattern with four-wheel pattern for performing, and calculates final wheel steering angle final_ δ according to the corresponding strategy of four-wheel pattern _ij, its corresponding calculative strategy is:

final_δ _ij＝δ _ij(7)

When target diversion pattern is adjustment modes, system is perform to turn to pattern with adjustment modes, and calculates final wheel steering angle final_ δ according to the corresponding strategy of adjustment modes _ij, its corresponding calculative strategy is:

final_δ _ij＝δ _ij' (8)

404) final wheel steering angle value final_ δ is exported _ij; Here ij=fl, fr, rl, rr, wherein fl represents the near front wheel, fr represents off front wheel, rl represents left rear wheel, rr represents off hind wheel.

10. the rotating direction control method of a kind of four-wheel independent steering automobile according to claim 1, is characterized in that:

Described step IV) in turn to execution module, the final wheel steering angle calculated according to turning to pattern Coordination module and the actual wheel corner of digital sampling and processing timely collection, produce corresponding control command, realize Vehicular turn.