CN104843057B - A kind of rotating direction control method of four-wheel independent steering automobile - Google Patents

Abstract

The invention belongs to motor turning control technology field, is related to a kind of rotating direction control method of four-wheel independent steering automobile, step is as follows：1) digital sampling and processing timely collection driver turns to intent information and vehicle condition information；2) according to step 1) data message, steering pattern discrimination module differentiates that target diversion pattern is the one kind in adjustment modes, four-wheel pattern, stage die formula I or stage die formula II；3) according to step 1) data message, wheel steering angle computing module calculate adjustment modes under wheel steering angle and four-wheel pattern under wheel steering angle；4) according to step 2) and step 3) result, steering pattern Coordination module determines the execution steering pattern of automobile, calculates final wheel steering angle and simultaneously passes it to turn to performing module and performs；Present invention efficiently solves the course changing control problem of four-wheel independent steering automobile, improves side force of tire utilization rate, steering stability and the safety of automobile are improved, while also reducing steering energy consumption.

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, more particularly, to a kind of steering control of four-wheel independent steering automobile Method processed.

Background technology

With the continuous improvement of automotive performance and road speed, the steering stability of automobile and safety are always vehicle and move Hot issue in mechanics study, the especially stability and safety problem during high speed steering.Turn as a kind of important automobile To control technology, four-wheel steering technology has just got more and more people's extensive concerning since the birth.With traditional front-wheel steer technology phase Than the trailing wheel of four-wheel steering technical controlling automobile participates in divertical motion together with front-wheel, is improved when automobile high-speed is turned to this Mobility when stability and low speed are turned to.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 skill Art.

In active rear steer technology, the front-wheel of automobile is controlled by steering wheel by driver, and trailing wheel is by steering control system System is controlled according to speed and front wheel angle.As active rear steer control system only has one controlled quentity controlled variable of trailing wheel corner, And which generally selects one of side slip angle or yaw velocity as control targe, and the steering stability of automobile is improved very It is limited.

Active four-wheel steering technology combines active front and active rear steer technology, and this kind of technology utilization orientation disk turns Angle is calculated the front wheels and rear wheels corner of automobile simultaneously as steering order by controller according to steering wheel angle.Actively four rotate The shortcoming of active rear steer technology is overcome to technology, two fingers of side slip angle or yaw velocity can be met simultaneously Mark.However, active 4-wheel Steering Control System gives tacit consent to two front wheel angles and two trailing wheel corners are each equal, motor turning is have ignored When due to vertical load each wheel side force difference for causing of transfer, fail to realize stable direction by reasonable distribution side force of tire The further raising of property.Additionally, simple turn now to be intended to steering wheel rotor, fine setting during automobile straight-line travelling is also have ignored Trimming process, causes the unnecessary consumption of energy.

The content of the invention

The invention aims to overcome above-mentioned the deficiencies in the prior art and provide a kind of four-wheel independent steering automobile Rotating direction control method, efficiently solves the course changing control problem of four-wheel independent steering automobile, improves side force of tire utilization rate, changes The steering stability of kind four-wheel independent steering automobile and safety, while reducing the steering energy consumption of automobile.

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

A kind of rotating direction control method of four-wheel independent steering automobile, the method are comprised the following steps that：

I) digital sampling and processing Real-time Collection driver turns to intent information and vehicle condition parameter information, and to adopting The driver of collection turns to intent information and vehicle condition parameter information and carries out preliminary treatment；

II) according to step I) driver turn to intent information and vehicle condition parameter information, steering pattern discrimination module In being adjustment modes, four-wheel pattern, stage die formula I or stage die formula II by the target diversion pattern discrimination of automobile under current state One kind；

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

IV) according to step II) and step III) result, steering pattern Coordination module enters to the target diversion pattern of automobile Row coordinates conversion, determines the execution steering pattern of automobile, calculates final wheel steering angle numerical value, and final wheel steering angle numerical value is passed It is handed to steering performing module to perform.

The step I) in digital sampling and processing respectively with steering pattern discrimination module, wheel steering angle computing module It is connected with performing module is turned to, described steering pattern Coordination module connects steering pattern discrimination module, wheel steering angle meter simultaneously Calculate module and turn to performing module；

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

The acquisition module Real-time Collection driver turns to intent information and vehicle condition parameter information；The acquisition module Including longitudinal vehicle speed sensor, lateral vehicle speed sensor, steering wheel angle sensor, gyroscope and wheel steering angle sensor；Adopt The driver of collection module collection turn to intent information and vehicle condition parameter information include turn signal state, actual wheel corner, Steering wheel angle δ_SW, longitudinal vehicle velocity V_x, lateral vehicle velocity V_yWith yaw velocity ω_r；

The processing module to gather driver turn to intent information and vehicle condition parameter information preliminary treatment be Fingering row iu is changed 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, V_yRepresent lateral speed；

The step II) in, turn signal state, longitudinal speed of the steering pattern discrimination module according to timely collection V_x, longitudinal speed threshold value V_Tx, steering wheel angle δ_SWWith steering wheel angle threshold value δ_TSWInformation, the target diversion pattern of automobile is sentenced One kind that Wei be in adjustment modes, four-wheel pattern, stage die formula I or stage die formula II, and result is sent to into steering pattern association Mode transfer block；

The target diversion pattern discrimination by automobile is adjustment modes, four-wheel pattern, stage die formula I or stage die formula II In a kind of concrete differentiation the step of it is as follows：

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

If steering indicating light is opened, then it is assumed that motor turning pattern should be converted to four-wheel pattern；If steering indicating light is not opened, Longitudinal speed is judged；

If longitudinal speed is more than or equal to the threshold value of setting, i.e. V_x≥V_Tx, then it is assumed that motor turning pattern should be converted to four Wheel pattern；If longitudinal speed 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 it is assumed 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 it is assumed that motor turning pattern should be converted to tune Integral pattern；

102) setting time step is T_p, by step 101) current judged result compared with upper time step judged result Compared with making final judgement：

If current judged result is four-wheel pattern, upper time step judged result is four-wheel pattern, then target diversion pattern It is judged to four-wheel pattern；

If current judged result is four-wheel pattern, upper time step judged result is adjustment modes, then target diversion pattern It is judged to stage die formula I；

If current judged result is adjustment modes, upper time step judged result is four-wheel pattern, then target diversion pattern It is judged to stage die formula II；

If current judged result is adjustment modes, upper time step judged result is adjustment modes, then target diversion pattern It is judged to adjustment modes；

103) preserve step 101) current judged result；

104) export target diversion pattern.

The step III) in, wheel steering angle computing module is turned using the driver of digital sampling and processing acquisition process The wheel calculated to intent information and vehicle condition parameter information under wheel steering angle numerical value and four-wheel pattern under adjustment modes turns Angle numerical value, and result is sent to into steering pattern Coordination module.Wheel steering angle computing module includes adjustment modes wheel steering angle meter Calculate module and four-wheel pattern wheel steering angle computing module two parts.

Steering wheel angle δ of the adjustment modes wheel steering angle computing module according to timely collection_SWCalculate under adjustment modes Wheel steering angle numerical value, concrete calculating process is：

201) according to steering wheel angle δ_SWAnd steering gear ratio i of setting, calculate front axle center effective rotation δ_f', institute State 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_fFront tread is represented, L represents wheelbase；

If 203) automobile left-hand rotation (i.e. δ_SW>=0), now interior front-wheel be the near front wheel, outer front-wheel be 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 interior front-wheel be off-front wheel, outer front-wheel be the near front wheel, then make δ_fl'=δ_of', δ_fr'=δ_if'；

Wherein, δ_fl' represent adjustment modes under the near front wheel corner, δ_fr' represent adjustment modes under off-front wheel corner；

204) it is 0, i.e. δ to give two trailing wheel corner numerical value_rl'=δ_rr'=0；

Wherein, δ_rl' represent adjustment modes under left rear wheel corner, δ_rr' represent adjustment modes under off hind wheel corner；

205) the numerical value δ of lower four wheel steering angles of output adjustment pattern_ij' (ij=fl, fr, rl, rr, wherein fl tables here Show that the near front wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel).

Steering wheel angle δ of the four-wheel pattern wheel steering angle computing module according to timely collection_SW, longitudinal vehicle velocity V_x, matter Heart lateral deviation angle beta, yaw velocity ω_rThe wheel steering angle numerical value under four-wheel pattern is calculated, concrete calculating process is：

301) according to steering wheel angle δ_SWAnd steering gear ratio i of setting, calculate and refer to front wheel angleThe ginseng The computing formula for examining front wheel angle is：

302) according to longitudinal vehicle velocity V_xWith refer to front wheel angleCalculate the preferable yaw velocity ω of automobile_rdAnd ideal Side slip angle β_d, computing formula is as follows：

And,|ω_rd|≤|0.85·μ·g/V_x|

Wherein, G_ωThe steady-state gain of preferable yaw velocity is represented, K represents the stability factor of vehicle, τ_ωRepresent inertia Link time constant, μ represent coefficient of road adhesion, and g represents acceleration of gravity, a, b represent respectively automobile barycenter to axle away from From behalf Laplace operator；

303) side slip angle β is calculated with preferable side slip angle β_d, and yaw velocity ω_rWith preferable yaw angle speed Degree 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 refer to front wheel angle Front and rear wheel corner base value δ is calculated using model following optimal control law_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,

Wherein, I_zRepresent the yaw rotation inertia of automobile, k_f、k_rFront and rear wheel cornering stiffness is represented, m represents complete vehicle quality, P For Riccati equation PA+Q+A^TP-PBR^-1B^TThe solution of P=0, Q are control parameter.R is control parameter.

305) calculate wheel steering angle increment Δ δ_F1、Δδ_F2、Δδ_R1、Δδ_R2, its formula is as follows：

And,

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

306) utilize and refer to front wheel angleLongitudinal vehicle velocity V_x, longitudinal speed threshold value V_TxWith yaw-rate error e_ω, it is right Motion state of automobile is judged；According to different motion state of automobile, using wheel steering angle base value δ_F、δ_RWith increment Δ δ_F1、Δ δ_F2、Δδ_R、₁Δδ_R2, with reasonable distribution side force of tire as target, four-wheel pattern wheel steering angle is calculated, it is specific as follows：

WhenWhen, automobile is judged in high speed, left-hand rotation, understeer state, the wheel taken turns Angle calculative strategy is：

WhenWhen, judge automobile in high speed, left-hand rotation, oversteering state, the wheel steering angle taken Calculative strategy is：

WhenWhen, automobile is judged in high speed, right-hand rotation, oversteering state, the wheel taken turns Angle calculative strategy is：

WhenWhen, judge automobile in high speed, right-hand rotation, understeer state, the wheel steering angle taken Calculative strategy is：

WhenWhen, judging that automobile is in low speed, left-hand rotation, understeer state, the wheel taken turns Angle calculative strategy is：

WhenWhen, judging that automobile is in low speed, left-hand rotation, oversteering state, the wheel taken turns Angle calculative strategy is：

WhenWhen, judging that automobile is in low speed, right-hand rotation, oversteering state, the wheel taken turns Angle calculative strategy is：

WhenWhen, judging that automobile is in low speed, right-hand rotation, understeer state, the wheel taken turns Angle calculative strategy 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_rlTable Show the left rear wheel corner under four-wheel pattern, δ_rrRepresent the off hind wheel corner under four-wheel pattern；

307) export the numerical value δ of lower four wheel steering angles of four-wheel pattern_ij(ij=fl, fr, rl, rr here, wherein fl are represented The near front wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel).

The step IV) in, the wheel steering angle numerical value δ under target diversion pattern, adjustment modes according to automobile_ij' and four The lower wheel steering angle numerical value δ of wheel pattern_ij, steering pattern Coordination module coordinates conversion to the target diversion pattern of automobile, really Determine the execution steering pattern of automobile, calculate final wheel steering angle and result of calculation is sent to into steering performing module.

The execution steering pattern for determining automobile simultaneously calculates final wheel steering angle and comprises the following steps that：

401) by reading timer internal working mark, judge whether the front steering pattern of automobile is transition mode and is somebody's turn to do Transition mode is not completed；

If 402) timer internal works, now do not allow to carry out steering pattern conversion, the forward of reading and saving To pattern and intervalometer running time T and before steering pattern to perform steering pattern, according to the calculating of corresponding calculative strategy most Whole wheel steering angle numerical value；

If 403) timer internal does not work, now allow to carry out steering pattern conversion, target diversion pattern is believed Breath is differentiated：

When target diversion pattern is stage die formula I, it is front steering pattern to start intervalometer and preserve stage die formula I, is System is with stage die formula I to perform steering pattern, and the corresponding strategy according to stage die formula I calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

Wherein, T represents intervalometer run time；T_totalRepresent the transition mode total duration of intervalometer setting, T_totalValue With the time step T set in steering pattern discrimination module_pUnanimously；

When target diversion pattern is stage die formula II, it is front steering pattern to start intervalometer and preserve stage die formula II, System is with stage die formula II to perform steering pattern, and the corresponding strategy according to stage die formula II calculates final wheel steering angle final_δ_ij, its corresponding calculative strategy is：

When target diversion pattern is four-wheel pattern, system with four-wheel pattern to perform steering pattern, and according to four-wheel mould The corresponding strategy of formula calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

final_δ_ij=δ_ij (7)

When target diversion pattern be adjustment modes when, system with adjustment modes as perform steering pattern, and according to adjustment mould The corresponding strategy of formula calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

final_δ_ij=δ_ij' (8)

404) export final wheel steering angle value final_ δ_ij(ij=fl, fr, rl, rr here, wherein fl represent left front Wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel).

Described step IV) in steering performing module, according to steering pattern Coordination module calculate final wheel steering angle And the actual wheel corner of digital sampling and processing timely collection, corresponding control instruction is produced, realizes that vehicle turns To.

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

Instant invention overcomes some shortcomings in existing four-wheel steering technology, provide one kind for four-wheel independent steering automobile Effective rotating direction control method.

The present invention can be turned to according to driver and be intended to the steering pattern of automobile is determined as adjustment with vehicle condition information One kind in pattern, four-wheel pattern, stage die formula I or stage die formula II, and the corresponding strategy according to each steering pattern calculates car Wheel corner.Wherein, the conversion between adjustment modes and four-wheel pattern reduces the steering energy expenditure of automobile of knowing clearly, stage die formula I and The presence of stage die formula II then ensure that and seamlessly transit between adjustment modes and four-wheel pattern.

Four-wheel pattern wheel steering angle computational methods in the present invention, can not only meet side slip angle and yaw angle simultaneously Speed two mainly turns to index, additionally it is possible to which the reasonable distribution for significantly improving side force of tire is utilized, and realizes that four-wheel independently turns To the further raising of stability of automobile and steering safety.

Description of the drawings

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

Accompanying drawing 2 is target diversion pattern discrimination flow chart；

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

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

Accompanying drawing 5 is that steering pattern coordinates flow chart.

Specific embodiment

The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.The present embodiment is with technical solution of the present invention Premised on implemented, give detailed embodiment and specific operating process, but protection scope of the present invention be not limited to Following embodiments.

As shown in figure 1, the rotating direction control method of four-wheel independent steering automobile provided in an embodiment of the present invention includes following step Suddenly：

I) digital sampling and processing Real-time Collection driver turns to intent information and vehicle condition parameter information, and to adopting The driver of collection turns to intent information and vehicle condition parameter information and carries out preliminary treatment；

II) according to step I) driver turn to intent information and vehicle condition parameter information, steering pattern discrimination module In being adjustment modes, four-wheel pattern, stage die formula I or stage die formula II by the target diversion pattern discrimination of automobile under current state One kind；

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

IV) according to step II) and step III) result, steering pattern Coordination module enters to the target diversion pattern of automobile Row coordinates conversion, determines the execution steering pattern of automobile, calculates final wheel steering angle numerical value, and final wheel steering angle numerical value is passed It is handed to steering performing module to perform.

The step I) in digital sampling and processing respectively with steering pattern discrimination module, wheel steering angle computing module It is connected with performing module is turned to, described steering pattern Coordination module connects steering pattern discrimination module, wheel steering angle meter simultaneously Calculate module and turn to performing module；

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

The acquisition module Real-time Collection driver turns to intent information and vehicle condition parameter information；The acquisition module Including longitudinal vehicle speed sensor, lateral vehicle speed sensor, steering wheel angle sensor, gyroscope and wheel steering angle sensor；Adopt The driver of collection module collection turn to intent information and vehicle condition parameter information include turn signal state, actual wheel corner, Steering wheel angle δ_SW, longitudinal vehicle velocity V_x, lateral vehicle velocity V_yWith yaw velocity ω_r；

The processing module to gather driver turn to intent information and vehicle condition parameter information preliminary treatment be Fingering row iu is changed 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, V_yRepresent lateral speed；

The step II) in, turn signal state, longitudinal speed of the steering pattern discrimination module according to timely collection V_x, longitudinal speed threshold value V_Tx, steering wheel angle δ_SWWith steering wheel angle threshold value δ_TSWInformation, the target diversion pattern of automobile is sentenced One kind that Wei be in adjustment modes, four-wheel pattern, stage die formula I or stage die formula II, and result is sent to into steering pattern association Mode transfer block；

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

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

If steering indicating light is opened, four-wheel mode flags position 1；If steering indicating light is not opened, longitudinal speed is carried out Judge；

Longitudinal speed threshold value V of setting_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 to steering wheel angle；

Direction initialization disk 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 with preserve front four-wheel mode flags position (go up a time step Four-wheel mode flags position, time step T in example_pFor 200ms) it is compared, differentiate vehicle target steering 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 updating；

104) export target diversion pattern.

The step III) in, wheel steering angle computing module is turned using the driver of digital sampling and processing acquisition process The wheel calculated to intent information and vehicle condition parameter information under wheel steering angle numerical value and four-wheel pattern under adjustment modes turns Angle numerical value, and result is sent to into steering pattern Coordination module.Wheel steering angle computing module includes adjustment modes wheel steering angle meter Calculate module and four-wheel pattern wheel steering angle computing module two parts.

As shown in figure 3, steering wheel angle δ of the adjustment modes wheel steering angle computing module according to timely collection_SWCalculate Wheel steering angle numerical value under adjustment modes, concrete calculating process is：

201) according to steering wheel angle δ_SWAnd steering gear ratio i of setting, calculate front axle center effective rotation δ_f', institute State 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：

Wherein, T_fFront tread is represented, L represents wheelbase；

If 203) automobile left-hand rotation (i.e. δ_SW>=0), now interior front-wheel be the near front wheel, outer front-wheel be 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 interior front-wheel be off-front wheel, outer front-wheel be the near front wheel, then make δ_fl'=δ_of', δ_fr'=δ_if'；

Wherein, δ_fl' represent adjustment modes under the near front wheel corner, δ_fr' represent adjustment modes under off-front wheel corner；

204) it is 0, i.e. δ to give two trailing wheel corner numerical value_rl'=δ_rr'=0；

Wherein, δ_rl' represent adjustment modes under left rear wheel corner, δ_rr' represent adjustment modes under off hind wheel corner；

205) the numerical value δ of lower four wheel steering angles of output adjustment pattern_ij' (ij=fl, fr, rl, rr, wherein fl tables here Show that the near front wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel).

As shown in figure 4, steering wheel angle δ of the four-wheel pattern wheel steering angle computing module according to timely collection_SW, longitudinal direction Vehicle velocity V_x, side slip angle β, yaw velocity ω_rThe wheel steering angle numerical value under four-wheel pattern is calculated, concrete calculating process is：

301) according to steering wheel angle δ_SWAnd steering gear ratio i of setting, calculate and refer to front wheel angleThe ginseng The computing formula for examining front wheel angle is：

302) according to longitudinal vehicle velocity V_xWith refer to front wheel angleCalculate the preferable yaw velocity ω of automobile_rdAnd ideal Side slip angle β_d, computing formula is as follows：

And,|ω_rd|≤|0.85·μ·g/V_x|

Wherein, G_ωThe steady-state gain of preferable yaw velocity is represented, K represents the stability factor of vehicle, τ_ωRepresent inertia Link time constant, μ represent coefficient of road adhesion, and g represents acceleration of gravity, a, b represent respectively automobile barycenter to axle away from From behalf Laplace operator；

303) side slip angle β is calculated with preferable side slip angle β_d, and yaw velocity ω_rWith preferable yaw angle speed Degree 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 refer to front wheel angle Front and rear wheel corner base value δ is calculated using model following optimal control law_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,

Wherein, I_zRepresent the yaw rotation inertia of automobile, k_f、k_rFront and rear wheel cornering stiffness is represented, m represents complete vehicle quality, P For Riccati equation PA+Q+A^TP-PBR^-1B^TThe solution of P=0, Q are control parameter.R is control parameter.

305) calculate wheel steering angle increment Δ δ_F1、Δδ_F2、Δδ_R1、Δδ_R2, its formula is as follows：

And,

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

306) utilize and refer to front wheel angleLongitudinal vehicle velocity V_x, longitudinal speed threshold value V_TxWith yaw-rate error e_ω, it is right Motion state of automobile is judged；According to different motion state of automobile, using wheel steering angle base value δ_F、δ_RWith increment Δ δ_F1、Δ δ_F2、Δδ_R、₁Δδ_R2, with reasonable distribution side force of tire as target, four-wheel pattern wheel steering angle is calculated, it is specific as follows：

Longitudinal speed threshold value V_TxIt is set as 10m/s；

WhenWhen, judge automobile in high speed, left-hand rotation, understeer state, the wheel taken Corner calculative strategy is：

WhenWhen, judge automobile in high speed, left-hand rotation, oversteering state, the wheel taken Corner calculative strategy is：

WhenWhen, judge automobile in high speed, right-hand rotation, oversteering state, the wheel taken Corner calculative strategy is：

WhenWhen, judge automobile in high speed, right-hand rotation, understeer state, the wheel taken Corner calculative strategy is：

WhenWhen, judge that automobile is in low speed, left-hand rotation, understeer state, the wheel taken Corner calculative strategy is：

WhenWhen, judge that automobile is in low speed, left-hand rotation, oversteering state, the wheel taken Corner calculative strategy is：

WhenWhen, judge that automobile is in low speed, right-hand rotation, oversteering state, the wheel taken Corner calculative strategy is：

WhenWhen, judge that automobile is in low speed, right-hand rotation, understeer state, the wheel taken Corner calculative strategy 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_rlTable Show the left rear wheel corner under four-wheel pattern, δ_rrRepresent the off hind wheel corner under four-wheel pattern；

307) export the numerical value δ of lower four wheel steering angles of four-wheel pattern_ij(ij=fl, fr, rl, rr here, wherein fl are represented The near front wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel).

The step IV) in, the wheel steering angle numerical value δ under target diversion pattern, adjustment modes according to automobile_ij' and four The lower wheel steering angle numerical value δ of wheel pattern_ij, steering pattern Coordination module coordinates conversion to the target diversion pattern of automobile, really Determine the execution steering pattern of automobile, calculate final wheel steering angle and result of calculation is sent to into steering performing module.

As shown in figure 5, the execution steering pattern for determining automobile calculating final wheel steering angle and comprising the following steps that：

401) by reading timer internal working mark position, judge automobile front steering pattern be whether transition mode and The transition mode is not completed；

402) if timer internal working mark position is 1, now do not allow to carry out steering pattern conversion, reading and saving Simultaneously steering pattern was execution steering pattern in the past for front steering pattern and intervalometer running time T, according to corresponding calculative strategy meter Final wheel steering angle numerical value；

403) if timer internal working mark position is 0, now allow to carry out steering pattern conversion, to target diversion mould Formula information is differentiated：

When target diversion pattern is stage die formula I, it is front steering pattern to start intervalometer and preserve stage die formula I, is System is with stage die formula I to perform steering pattern, and the corresponding strategy according to stage die formula I calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

Wherein, T represents intervalometer run time；T_totalRepresent the transition mode total duration of intervalometer setting, T_totalValue With the time step T set in steering pattern discrimination module_pUnanimously, 200ms is taken as in example；

When target diversion pattern is stage die formula II, it is front steering pattern to start intervalometer and preserve stage die formula II, System is with stage die formula II to perform steering pattern, and the corresponding strategy according to stage die formula II calculates final wheel steering angle final_δ_ij, its corresponding calculative strategy is：

When target diversion pattern is four-wheel pattern, system with four-wheel pattern to perform steering pattern, and according to four-wheel mould The corresponding strategy of formula calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

final_δ_ij=δ_ij (7)

When target diversion pattern be adjustment modes when, system with adjustment modes as perform steering pattern, and according to adjustment mould The corresponding strategy of formula calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

final_δ_ij=δ_ij' (8)

404) export final wheel steering angle value final_ δ_ij(ij=fl, fr, rl, rr here, wherein fl represent left front Wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel).

Described step IV) in, turn to performing module and receive the final wheel turn that steering pattern Coordination module is calculated simultaneously The actual wheel corner of angle and digital sampling and processing timely collection, and utilize final wheel steering angle and actual wheel Difference between corner produces corresponding control instruction, realizes the steering of vehicle.

This example provides a kind of rotating direction control method of four-wheel independent steering automobile.According to the steering control that this example is provided Method processed, active rear steer technology can be overcome to improve, and motor turning stability is limited and active four-wheel steering technology is not examined Consider the shortcoming of analysis of wheel vertical load transfer, realize that the motor turning of four-wheel independence further improves the manipulation of automobile while control Stability and steering safety, improve side force of tire utilization rate, also reduce the ability consumption of steering to a certain extent.

The invention is not restricted to examples detailed above, various changes can be carried out.

Claims (8)

1. a kind of rotating direction control method of four-wheel independent steering automobile, it is characterised in that comprise the steps：

I) digital sampling and processing Real-time Collection driver turns to intent information and vehicle condition parameter information, and to collection Driver turns to intent information and vehicle condition parameter information and carries out preliminary treatment；

II) according to step I) driver turn to intent information and vehicle condition parameter information, steering pattern discrimination module ought Under front state, the target diversion pattern discrimination of automobile is in adjustment modes, four-wheel pattern, stage die formula I or stage die formula II Kind；

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

IV) according to step II) and step III) result, steering pattern Coordination module assisted to the target diversion pattern of automobile Turn and change, determine the execution steering pattern of automobile, calculate final wheel steering angle numerical value, and final wheel steering angle numerical value is transferred to Turn to performing module to perform；

The step II) in, turn signal state, longitudinal vehicle velocity V of the steering pattern discrimination module according to timely collection_x, longitudinal direction Speed threshold value V_Tx, steering wheel angle δ_SWWith steering wheel angle threshold value δ_TSWInformation, is tune by the target diversion pattern discrimination of automobile One kind in integral pattern, four-wheel pattern, stage die formula I or stage die formula II, and result is sent to into steering pattern Coordination module；

During the target diversion pattern discrimination by automobile is adjustment modes, four-wheel pattern, stage die formula I or stage die formula II The step of a kind of concrete differentiation, is as follows：

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

If steering indicating light is opened, then it is assumed that motor turning pattern should be converted to four-wheel pattern；If steering indicating light is not opened, to vertical Judged to speed；

If longitudinal speed is more than or equal to the threshold value of setting, then it is assumed that motor turning pattern should be converted to four-wheel pattern；If vertical To speed 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 it is assumed that motor turning pattern should be converted to four-wheel pattern；If Threshold value of the steering wheel angle less than setting, then it is assumed that motor turning pattern should be converted to adjustment modes；

102) setting time step is T_p, by step 101) current judged result be compared with upper time step judged result, do Go out final judgement：

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

If current judged result is four-wheel pattern, upper time step judged result is adjustment modes, then target diversion mode decision For stage die formula I；

If current judged result is adjustment modes, upper time step judged result is four-wheel pattern, then target diversion mode decision For stage die formula II；

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

103) preserve step 101) current judged result；

104) export target diversion pattern.

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

The step I) in digital sampling and processing respectively with steering pattern discrimination module, wheel steering angle computing module and turn It is connected to performing module, described steering pattern Coordination module connects steering pattern discrimination module, wheel steering angle simultaneously and calculates mould Block and steering performing module；

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

The acquisition module Real-time Collection driver turns to intent information and vehicle condition parameter information；The acquisition module includes Longitudinal vehicle speed sensor, lateral vehicle speed sensor, steering wheel angle sensor, gyroscope and wheel steering angle sensor；Collection mould The driver of block collection turns to intent information and vehicle condition parameter information includes turn signal state, actual wheel corner, direction Disk corner δ_SW, longitudinal vehicle velocity V_x, lateral vehicle velocity V_yWith yaw velocity ω_r；

The preliminary treatment that the processing module turns to intent information and vehicle condition parameter information to the driver for gathering is fingering Row iu is changed 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, V_yRepresent lateral speed.

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

The step III) in, wheel steering angle computing module turns to meaning using the driver of digital sampling and processing acquisition process Figure information and vehicle condition parameter information calculate the wheel steering angle number under wheel steering angle numerical value and four-wheel pattern under adjustment modes Value, and result is sent to into steering pattern Coordination module；

The wheel steering angle computing module includes that adjustment modes wheel steering angle computing module and four-wheel pattern wheel steering angle calculate mould Block two parts；

Steering wheel angle δ of the adjustment modes wheel steering angle computing module according to timely collection_SW, calculate under adjustment modes Wheel steering angle numerical value；

Steering wheel angle δ of the four-wheel pattern wheel steering angle computing module according to timely collection_SW, longitudinal vehicle velocity V_x, matter Heart lateral deviation angle beta and yaw velocity ω_r, calculate the wheel steering angle numerical value under four-wheel pattern.

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

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

201) according to steering wheel angle δ_SWAnd steering gear ratio i of setting, calculate front axle center effective rotation δ_f', it is described before 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_fFront tread is represented, L represents wheelbase；

If 203) automobile turn left, now interior front-wheel be the near front wheel, outer front-wheel be off-front wheel, then make δ_fl'=δ_if', δ_fr'= δ_of'；If automobile turn right, now interior front-wheel be off-front wheel, outer front-wheel be the near front wheel, then make δ_fl'=δ_of', δ_fr'=δ_if'；

Wherein, δ_fl' represent adjustment modes under the near front wheel corner, δ_fr' represent adjustment modes under off-front wheel corner；

204) it is 0 to give two trailing wheel corner numerical value, specifically, order：δ_rl'=δ_rr'=0；

Wherein, δ_rl' represent adjustment modes under left rear wheel corner, δ_rr' represent adjustment modes under off hind wheel corner；

205) the numerical value δ of lower four wheel steering angles of output adjustment pattern_ij'；Here ij=fl, fr, rl, rr, wherein fl represent left Front-wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel.

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

The concrete calculating process of wheel steering angle numerical value that calculates under four-wheel pattern is：

301) according to steering wheel angle δ_SWAnd steering gear ratio i of setting, calculate and refer to front wheel angleThe reference front-wheel The computing formula of corner is：

302) according to longitudinal vehicle velocity V_xWith refer to front wheel angleCalculate the preferable yaw velocity ω of automobile_rdWith preferable barycenter side Drift 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 preferable yaw velocity；

K represents the stability factor of vehicle；

τ_ωRepresent inertial element time constant；

μ represents coefficient of road adhesion；

G represents acceleration of gravity；

A, b represent automobile barycenter to axle distance respectively；

Behalf Laplace operator；

303) side slip angle β is calculated with preferable side slip angle β_d, and yaw velocity ω_rWith preferable yaw velocity ω_rd Between 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 refer to front wheel angleUtilize Model following optimal control law calculates front and rear wheel corner base value δ_F、δ_R, model following optimal control law is as follows：

$\begin{array}{c}u=-R^{-1}{B}^{T}Pe-R^{-1}{B}^T{(A^T-{\mathrm{PBR}}^{-1}{B}^T)}^{-1}{\mathrm{PB}}_d{u}_d\\ +R^{-1}{B}^T{(A^T-{\mathrm{PBR}}^{-1}{B}^T)}^{-1}P(A-A_d)x_d\end{array}---\left(3\right)$

And, u=[δ_F δ_R]^T,

x_d=[β_d ω_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 control parameter；

R is control parameter；

305) calculate wheel steering angle increment Δ δ_F1、Δδ_F2、Δδ_R1、Δδ_R2, its formula is as follows：

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

And,

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

306) utilize and refer to front wheel angleLongitudinal vehicle velocity V_x, longitudinal speed threshold value V_TxWith yaw-rate error e_ω, to automobile Kinestate is judged；According to different motion state of automobile, using wheel steering angle base value δ_F、δ_RWith increment Δ δ_F1、Δδ_F2、Δ δ_R1、Δδ_R2, with reasonable distribution side force of tire as target, four-wheel pattern wheel steering angle is calculated, it is specific as follows：

Work as V_x≥V_Tx,e_ωDuring ＜ 0, judge automobile in high speed, left-hand rotation, understeer state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x≥V_Tx,e_ωWhen >=0, judge automobile in high speed, left-hand rotation, oversteering state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x≥V_Tx,e_ωDuring ＜ 0, judge automobile in high speed, right-hand rotation, oversteering state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x≥V_Tx,e_ωWhen >=0, judge automobile in high speed, right-hand rotation, understeer state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x＜ V_Tx,e_ωDuring ＜ 0, judge that automobile is in low speed, left-hand rotation, understeer state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x＜ V_Tx,e_ωWhen >=0, judge that automobile is in low speed, left-hand rotation, oversteering state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x＜ V_Tx,e_ωDuring ＜ 0, judge that automobile is in low speed, right-hand rotation, oversteering state, the wheel steering angle meter taken Calculating strategy is：

Work as V_x＜ V_Tx,e_ωWhen >=0, judge that automobile is in low speed, right-hand rotation, understeer state, the wheel steering angle meter taken Calculating strategy 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 four Left rear wheel corner under wheel pattern, δ_rrRepresent the off hind wheel corner under four-wheel pattern；

307) export the numerical value δ of lower four wheel steering angles of four-wheel pattern_ij；Here ij=fl, fr, rl, rr, wherein fl represent left front Wheel, fr represent that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel.

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

The step IV) in, the wheel steering angle numerical value δ under target diversion pattern, adjustment modes according to automobile_ij' and four-wheel mould The lower wheel steering angle numerical value δ of formula_ij, steering pattern Coordination module coordinates conversion to the target diversion pattern of automobile, determines vapour The execution steering pattern of car, calculates final wheel steering angle and result of calculation is sent to steering performing module.

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

The execution steering pattern for determining automobile simultaneously calculates final wheel steering angle and comprises the following steps that：

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

If 402) timer internal works, now do not allow to carry out steering pattern conversion, the front steering mould of reading and saving Simultaneously steering pattern, to perform steering pattern, calculated final car according to corresponding calculative strategy in the past for formula and intervalometer running time T Wheel corner numerical value；

If 403) timer internal does not work, now allow to carry out steering pattern conversion, target diversion pattern information is entered Row differentiates：

When target diversion pattern is stage die formula I, starts intervalometer and preserve stage die formula I for front steering pattern, system with Stage die formula I is to perform steering pattern, and the corresponding strategy according to stage die formula I calculates final wheel steering angle final_ δ_ij, its Accordingly calculative strategy is：

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

Wherein, T represents intervalometer run time；

T_totalRepresent the transition mode total duration of intervalometer setting, T_totalThe time set in value and steering pattern discrimination module Step T_pUnanimously；

When target diversion pattern is stage die formula II, start intervalometer and stage die formula II is preserved for front steering pattern, system With stage die formula II to perform steering pattern, and the corresponding strategy according to stage die formula II calculates final wheel steering angle final_ δ_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 with four-wheel pattern to perform steering pattern, and according to four-wheel pattern Corresponding strategy calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

final_δ_ij=δ_ij (7)

When target diversion pattern is adjustment modes, system with adjustment modes to perform steering pattern, and according to adjustment modes Corresponding strategy calculates final wheel steering angle final_ δ_ij, its corresponding calculative strategy is：

final_δ_ij=δ_ij' (8)

404) export final wheel steering angle value final_ δ_ij；Here ij=fl, fr, rl, rr, wherein fl represent the near front wheel, fr tables Show that off-front wheel, rl represent that left rear wheel, rr represent off hind wheel.

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

Described step IV) in steering performing module, according to steering pattern Coordination module calculate final wheel steering angle and The actual wheel corner of digital sampling and processing timely collection, produces corresponding control instruction, realizes Vehicular turn.