CN104760594B - Wheel torque distribution method for achieving lowest instant energy consumption - Google Patents

Abstract

The invention discloses a wheel torque distribution method for achieving lowest instant energy consumption. The method comprises the following steps: (1) a vehicle driving speed, a steering wheel turning angle and a yaw speed are measured through sensors; (2) a differential torque between driving wheels at the left and right sides is calculated; and (3) total instant electricity consumption of a whole vehicle is calculated under present working conditions of demanded driving torque, driving speed and differentia torque to obtain torques of a left front wheel, a right front wheel, a left rear wheel and a right rear wheel when the total instant electricity consumption of the whole vehicle is the lowest, and the torques are distributed to the corresponding wheels. When the vehicle is turned, the torque distribution method realizes the reduction of vehicle turning resistance, and the vehicle power consumption is the lowest to achieve the optimal energy saving effect.

Description

The minimum wheel torque distribution method of instantaneous energy consumption

Technical field

The present invention relates to automotive wheel torque distribution method, particularly to the wheel torque distribution that a kind of instantaneous energy consumption is minimum Method.

Background technology

Each wheel independent driving automobile refer to each driving wheel can independent output driving torque, i.e. torque can be in each drive Arbitrarily distribute according to control law between driving wheel.Such automobile is capable of good control stability, dynamic property and its passes through Property, and possess suitable driving maneuver and Driving, it is the commonly used drive form of high-performance sports car.This Outward, each wheel independently drives the form being not limited to power source, can be that traditional combustion engine drives, but also hybrid power drives or pure Motorized motions, for example, realizing the independent In-wheel-motor driving system driving using wheel hub motor or wheel motor is exactly respectively to take turns now The Typical Representative of independent driving automobile, he represents the development trend of following electric automobile.Such as, the super four-wheel of Honda sh-awd Each wheel independent driving system under the traditional power sources such as independent driving, Audi's sports type differential mechanism, and such as Mitsubishi colt ev, The Electric Motor Wheel such as keio eliica, mini qed independently drive the Typical Representative that sample car is all the independent actuation techniques application of each wheel.

Currently for each wheel torque separate allocation approach aspect, mainly concentrate with electric drive anti-sliding control, direct yaw The aspects such as each wheel torque distribution for the purpose of moment of couple control.Due to each wheel independent driving automobile, respectively to take turns torque individually controllable, turns Speed and torque are easily obtained again, and motor responds fast, precise control, and therefore controlling in Anti-slip regulation is had substantially compared with traditional vehicle Advantage.Simultaneously because its each motor torque is individually controllable, can be produced by the driving torque that internal outboard wheels apply not wait Direct yaw moment, improves control stability and the turning mobility of wheel.Currently for electric automobile energy saving control it is common that Based on the regulation to motor operating point, it is allowed to be operated in high efficient district, or consider the contribution to economy for the regenerative braking.However, When turning due to the reason of wheel steering angle and slip angle of tire, its front-wheel side force will produce one along the vehicle body longitudinal axis to vehicle The counter-force of line, thus leading to vehicle to reduce speed without reason, increased energy ezpenditure.Research finds, drives vapour for each wheel is independent Car turn when, can by reasonable distribution wheel between torque make its turning resistance reduce, thus further raising car load economy.

Content of the invention

The invention provides distribution method between a kind of torque wheel for automobile when turning, its objective is to reduce car when turning Energy consumption, improved curved speed, and there is the energy consumption of minimum.

The technical scheme that the present invention provides is:

A kind of minimum wheel torque distribution method of instantaneous energy consumption, comprises the following steps:

Step one, travel speed v obtaining automobile by sensor measurement, steering wheel angle δ_swAnd yaw velocity

Step 2, use equation below, calculate the differential torque between the driving wheel of the left and right sides

$\mathrm{\δt}=m{v}^2\frac{{\mathrm{\δ}}_{\mathrm{sw}}{l}_r{r}_w}{i_s{d}_{t}l}$

Wherein, m is vehicle mass；V is travel speed；δ_swFor steering wheel angle；r_wFor vehicle wheel roll radius；i_sFor turning to System angular gear ratio；L is vehicle wheel base；l_rDistance for barycenter to rear axle；d_tFor automobile wheel track；

Step 3, in current demand driving torque t_req, under current driving speed v and current differential torque δ t operating mode, adopt Calculate car load instantaneously total power consumption e with below equation_com

$e_{\mathrm{com}}=\underset{0}{\overset{c}{\&integral;}}(\frac{t_{\mathrm{fl}}{\mathrm{\ω}}_{m\_\mathrm{fl}}}{{\mathrm{\η}}_{\mathrm{fl}}}+\frac{t_{\mathrm{fr}}{\mathrm{\ω}}_{m\_\mathrm{fr}}}{{\mathrm{\η}}_{\mathrm{fr}}}+\frac{t_{\mathrm{rl}}{\mathrm{\ω}}_{m\_\mathrm{fl}}}{{\mathrm{\η}}_{\mathrm{rl}}}+\frac{t_{\mathrm{rr}}{\mathrm{\ω}}_{m\_\mathrm{rr}}}{{\mathrm{\η}}_{\mathrm{rr}}})\mathrm{dt}$

Wherein, t_fl、t_fr、t_rl、t_rrIt is respectively the near front wheel, off-front wheel, left rear wheel, the torque of off hind wheel, ω_{m_fl}、ω_{m_fr}、 ω_{m_rl}、ω_{m_rr}For not Wei the near front wheel, off-front wheel, left rear wheel, off hind wheel rotating speed, η_fl、η_fr、η_rl、η_rrBe respectively the near front wheel, Off-front wheel, left rear wheel, the operating efficiency of off hind wheel motor, c is the total time of given cycle operating mode；

Try to achieve as car load instantaneously total power consumption e_comThe torque t of the near front wheel, off-front wheel, left rear wheel, off hind wheel when minimum_fl、t_fr、 t_rl、t_rr, and corresponding wheel is distributed in this torque.

Preferably, in step 2, before calculating the differential torque between two side drive wheel, calculate first with equation below Side acceleration

$a_y=\frac{v^2}{r}\≈\frac{v^2{\mathrm{\δ}}_{\mathrm{sw}}}{i_{s}l}$

And judge whether side acceleration is more than 0.6g, wherein, g is acceleration of gravity；

If so, then make the differential torque δ t=0 between two side drive wheel, and carry out step 3；

If it is not, then proceeding step 2.

Preferably, in step 2, after being calculated the differential torque between two side drive wheel, calculated using equation below Preferable yaw velocity

${\stackrel{\·}{\mathrm{\ψ}}}_r=\frac{v{\mathrm{\δ}}_{\mathrm{sw}}}{i_{s}l(1+k_w{v}^2)}$

Wherein, k_wFor stability of automobile factor；

And judge yaw velocityWhether more than preferable yaw velocity

If it is not, then keeping the differential torque δ t being calculated between two side drive wheel constant；

If so, then show that the differential torque that a upper controlling cycle introduces makes automobile be in ovdersteering, therefore using public as follows Formula is modified to differential torque

$\mathrm{\δt}\left(h\right)=\mathrm{\δt}(h-1)+p[\frac{v{\mathrm{\δ}}_{\mathrm{sw}}}{i_{s}l(1+k_w{v}^2)}-\stackrel{\·}{\mathrm{\ψ}}]$

Wherein δ t (h-1) is the differential torque of a upper controlling cycle output, and δ t (h) is calculated for this controlling cycle Differential torque, h be controlling cycle sequence number, p be proportionality coefficient.

Preferably, after being calculated differential torque δ t in step 2, judge whether δ t turns more than Automobile Maximum output Square t_max；If so, then make δ t=t_max；If otherwise maintaining δ t constant.

Preferably, step 3 include following step by step:

A) following formula is utilized to calculate vehicle wheel rotational speed

${\mathrm{\ω}}_m=\frac{v}{r_w}$

Wherein r_wFor vehicle wheel roll radius；

B) utilize equation below, calculate the torque relationship of the near front wheel and left rear wheel, and the torque of off-front wheel and off hind wheel Relation

t_fl+t_rl=(t_req+δt)/2

t_fr+t_rr=(t_req-δt)/2

C) in current demand driving torque t_req, under current driving speed v and current differential torque δ t operating mode, car load wink When total power consumption e_comIt is with regard to the near front wheel torque t_flWith off-front wheel torque t_frTwo-dimensional function, calculate described instantaneously total power consumption e_comMinimum of a value e_{com_min}, and corresponding the near front wheel torque t_fl, left rear wheel torque t_rl, off-front wheel torque t_fr, off hind wheel turns Square t_rr, and corresponding wheel is distributed in corresponding torque.

Preferably, in step c), the near front wheel torque range is carried out discrete, obtain some grades of the near front wheel torque, will The torque range of off-front wheel carries out discrete, obtains some grades of off-front wheel torque, calculate respectively in the near front wheel torque not at the same level and Instantaneous total power consumption e in the case of off-front wheel torque not at the same level_com, and find out its minimum of a value e_{com_min}Corresponding the near front wheel torque t_fl, left Rear wheel torque t_rl, off-front wheel torque t_fr, off hind wheel torque t_rr, and corresponding wheel is distributed in corresponding torque.

Preferably, by the near front wheel torque range-t_{ε_max}～t_{ε_max}Discrete turn to arithmetic progression t_fl(j), j=1...j, Tolerance is 10nm, i.e. t_fl(1)=[- t_{e_max}], t_fl(2)=([t_{e_max}]+10) nm ...,..., t_fl(j) =[t_{e_max}], wherein $j=\frac{\left[{2t}_{e\_\max }\right]}{10};$

By off-front wheel torque range-t_{ε_max}～t_{ε_max}Discrete turn to arithmetic progression t_fr(k), k=1...k, tolerance is 10nm, i.e. t_fr(1)=[- t_{e_max}], t_fr(2)=([t_{e_max}]+10) nm ...,..., t_fr(k)= [t_{e_max}], wherein $k=\frac{\left[{2t}_{e\_\max }\right]}{10}.$

Preferably, by vehicle wheel rotational speeds scope, requirement drive torque excursion, the change of left and right sidesing driving wheel torque differences Scope carries out discrete, obtains the vehicle wheel rotational speeds ω of some series_m(n), n=1...n, the requirement drive torque of some series t_req(m), left and right sidesing driving wheel torque differences δ t (i) of m=1...m and some series, i=1...i, and by the car under current working Wheel rotary speed, requirement drive torque, left and right sidesing driving wheel torque differences are rounded to immediate series.

Preferably, by vehicle wheel rotational speeds scope 0～ω_{m_max}Discrete turn to arithmetic progression ω_m(n), n=1...n, public Difference is 100r/min, i.e. ω_m(1)=0r/min, ω_m(2)=100r/min, ω_m(3)=200r/min ..., ω_m(n)= [ω_{m_max}] whereinAnd work as ω_m(n)≤ω_m＜ ω_m(n+1), when, make ω_m=ω_m(n)；

By requirement drive torque excursion 0～t_{req_max}Discrete turn to arithmetic progression t_req(m), m=1...m, tolerance is 10nm, i.e. t_req(1)=0nm, t_req(2)=10nm, t_req(3)=20nm ..., t_req(m)=[t_{req_max}], whereinAnd work as t_req(m)≤t_req＜ t_req(m+1), when, make t_req=t_req(m)；

By left and right sidesing driving wheel torque differences excursion-δ t_max～δ t_maxDiscrete turn to arithmetic progression δ t (i), i= 1...i, tolerance is 10nm, i.e. δ t (1)=[- δ t_max], δ t (2)=([- δ t_max]+10) nm ...,..., δ t (i)=[δ t_max], whereinAnd work as δ t (i)≤δ t ＜ δ t (i+1) When, make δ t=δ t (i).

The invention has the beneficial effects as follows: the present invention on the basis of linear two degrees of freedom whole vehicle model, by micro- to dynamics The derivation dividing equation, it may be determined that the left and right wheels driving torque in middle Steady-state in Low Speed turning driving for the automobile is poor, increases outside car Wheel torque, reduces inboard wheel torque simultaneously, produces positive yaw moment in order to reduce the purpose of turning resistance when realizing turning.This Outer the method has also considered the problem of the mechanical efficiency decline that the change of motor operating point leads to, thus being sought using offline circulation Excellent calculate instantaneous least energy consumption method it is determined that under a certain operating mode allocation rule between the minimum torque between centers of energy consumption, torque wheel. In automobile turning, torque distribution method of the present invention is applied to achieve minimizing automobile turning resistance, and automobile consumption Power minimum, reach optimal energy-saving effect.

Brief description

Fig. 1 is automobile force analysis figure of the present invention.

Fig. 2 is to distribute control method flow chart between torque wheel of the present invention.

Fig. 3 is the minimum each wheel torque allocation rule algorithm flow chart of instantaneous energy consumption.

Specific embodiment

The present invention is described in further detail below in conjunction with the accompanying drawings, to make those skilled in the art with reference to specification literary composition Word can be implemented according to this.

As shown in figure 1, for powered rear wheels independent driving automobile when turning, carrying out stressing conditions analysis.To vehicle When carrying out force analysis, Electric Motor Wheel independent driving automobile is reduced to two degrees of freedom car model.For front-wheel 21 and trailing wheel 22 Stressing conditions, its vehicle dynamic model equation can be set up as follows:

$m\stackrel{\·}{v}\cos \mathrm{\β}-m\frac{v^2}{r}\sin \mathrm{\β}=f_{\mathrm{xf}}\cos \mathrm{\δ}-f_{\mathrm{yf}}\sin \mathrm{\δ}+f_{\mathrm{xr}}-(f_f+f_w)---\left(1\right)$

$m\stackrel{\·}{v}\sin \mathrm{\β}+m\frac{v^2}{r}\cos \mathrm{\β}=f_{\mathrm{xy}}\sin \mathrm{\δ}+f_{\mathrm{yf}}\sin \mathrm{\δ}+f_{\mathrm{yr}}---\left(2\right)$

$j\stackrel{\text{\·\·}}{\mathrm{\ψ}}=(f_{\mathrm{xf}}\sin \mathrm{\δ}+f_{\mathrm{yf}}\cos \mathrm{\δ})l_f-f_{\mathrm{yr}}{l}_r---\left(3\right)$

In formula, m is vehicle mass；J is vehicle rotary inertia；V is speed；β is side slip angle；ψ is yaw angle；R is Vehicle turn radius；δ is front wheel angle；l_fFor front axle away from；l_rFor rear axle away from；f_xfFor front axle tangential force；f_xrFor rear axle tangential force； f_yfFor front axle side force；f_yrFor rear axle side force；f_fFor vehicle rolling resistance；f_wFor vehicle body windage.

Again because centripetal acceleration is represented by:

$\frac{v^2}{r}=v(\stackrel{\·}{\mathrm{\β}}+\stackrel{\·}{\mathrm{\ψ}})---\left(4\right)$

Assume that vehicle is currently static operating mode, that is, steady circular travels.Based on above-mentioned it is assumed thatJust have simultaneously WithThen understand that the tangential force sum on whole wheels is by formula (1)-formula (4):

$f=f_{\mathrm{xf}}+f_{\mathrm{xr}}=f_f+f_w+\mathrm{mv}\stackrel{\·}{\mathrm{\ψ}}(\frac{l_r}{l}\sin \mathrm{\δ}-\sin \mathrm{\β})---\left(5\right)$

Remove and identical tire drag during straight-line travelling and air drag item, then turning resistance f_rCan express As follows:

$f_r=\mathrm{mv}\stackrel{\·}{\mathrm{\ψ}}(\frac{l_r}{l}\sin \mathrm{\δ}-\sin \mathrm{\β})---\left(6\right)$

From above formula, when side force is less, side force is directly proportional to side drift angle, and side force is become with side acceleration Direct ratio.So, turning resistance becomes quadratic relation with side acceleration, becomes biquadratic relation with speed.Turning resistance will lead to When entering curved on the premise of car ACCEL aperture is constant, automobile resistance increases, speed declines automatically.For the mistake remaining unchanged Curved speed, increases accelerator pedal aperture when necessarily leading to driver excessively curved, then results in excessive power drain.

If running car is in bend, introduce the differential force δ f of left and right sidesing driving wheel_{x_r}Bring kinetic balance equation into, can In the hope of turning resistance now it is:

$f_r=\mathrm{mv}\stackrel{\·}{\mathrm{\ψ}}(\frac{l_r}{l}\sin \mathrm{\δ}-\sin \mathrm{\β})-\frac{d_t}{l}\mathrm{\δ}{f}_{x\_r}\sin \mathrm{\δ}---\left(7\right)$

As can be seen here, the introducing of Differential Driving power reduces the size of turning resistance, suitable on the premise of guaranteeing stability When the outer rear wheel drive torque of raising, reduce the resistance that inner rear wheel driving torque can be obviously reduced turning, thus saving drive Energy or power.

Work when the main Steady-state in Low Speed in the car of turning energy-conservation torque distribution control is turned, now side slip angle β is remote Less than front wheel angle δ, therefore for simplify control, simplified according to formula 7 and calculate left and right trailing wheel differential torque δ t:

$\mathrm{\δt}=m{v}^2\frac{{\mathrm{\δ}}_{\mathrm{sw}}{l}_r{r}_w}{i_s{d}_{t}l}---\left(8\right)$

In formula, m is vehicle mass；V is speed；δ_swFor steering wheel angle；r_wFor vehicle wheel roll radius；i_sFor steering Angular gear ratio；L is vehicle wheel base；l_rDistance for barycenter to rear axle；d_tFor automobile wheel track.Except automobile basic parameter in this formula m、r_w、i_s、l、l_r、d_tIn addition, remaining v and δ_swIt is and is easier on existing automobile to measure the parameter obtaining, v can pass through vapour Car bus obtains data, and because turning Energy Saving Control is not high for speed accuracy requirement, therefore v can also obtain from automobile instrument ?；δ_swCan be arranged in steering spindle on the automobile of electrical power-assisted steering function or esp electronic stability control function by possessing Steering-wheel torque rotary angle transmitter obtain.Said method reduces the need to automobile hardware device for the torque distribution control algorithm Ask.

As described in Figure 2, between torque wheel of the present invention, distribution control method flow process is as follows:

First, obtain the basic parameter of automobile, including vehicle mass m, vehicle wheel roll radius r_w, steering angular gear ratio i_s, vehicle wheel base l, barycenter to rear axle is apart from l_r, automobile wheel track d_t, and the traveling speed of automobile is obtained by bus or sensor Degree v, steering wheel angle δ_swAnd yaw angle ψ.

Secondly, calculate side acceleration.Using equation below

$a_y=\frac{v^2}{r}\≈\frac{v^2{\mathrm{\δ}}_{\mathrm{sw}}}{i_{s}l}$

The value of primary Calculation side acceleration, and judge whether it is more than 0.6g, wherein, g is acceleration of gravity.If big In, then show that automobile tire enters obvious nonlinear area, show that automobile storage is dangerous in unstability, now should not be in consideration turning section Can, so seasonal left and right sidesing driving wheel torque differences δ t=0；

If side acceleration is not more than 0.6g, show that automobile does not have unstability danger, available equation below calculates preferable Yaw velocity

${\stackrel{\·}{\mathrm{\ψ}}}_r=\frac{v{\mathrm{\δ}}_{\mathrm{sw}}}{i_{s}l(1+k_w{v}^2)}$

Wherein, k_wFor stability of automobile factor.

Judge yaw velocityWhether more than preferable yaw velocityIf it is less, showing that automobile did not have The phenomenon that degree turns to, now calculates left and right sidesing driving wheel torque differences δ t according to formula 8；

If it is greater, then show that the differential torque that a upper controlling cycle introduces makes automobile be in ovdersteering, therefore should phase The differential torque of output should be reduced, i.e. left and right wheels driving torque difference δ t.Differential torque reduce value by actual yaw velocity with The difference of preferable yaw velocity is multiplied by a proportionality coefficient p and determines, specific formula for calculation is as follows:

$\mathrm{\δt}\left(h\right)=\mathrm{\δt}(h-1)+p[\frac{v{\mathrm{\δ}}_{\mathrm{sw}}}{i_{s}l(1+k_w{v}^2)}-\stackrel{\·}{\mathrm{\ψ}}]$

Wherein δ t (h-1) is the differential torque of a upper controlling cycle output, and δ t (h) is calculated for this controlling cycle Differential torque, h be controlling cycle sequence number, p be proportionality coefficient.

It is calculated it after left and right wheels driving torque difference δ t with wheel hub motor maximum output torque t_max, judge that δ t is No more than t_max, if it is, by motor torque capacity t_maxIt is assigned to δ t；If it is not, then maintaining δ t constant.

Finally, in current demand driving torque t_req, under current driving speed v and current differential torque δ t operating mode, adopt Below equation calculates car load instantaneously total power consumption e_com

$e_{\mathrm{com}}=\underset{0}{\overset{c}{\&integral;}}(\frac{t_{\mathrm{fl}}{\mathrm{\ω}}_{m\_\mathrm{fl}}}{{\mathrm{\η}}_{\mathrm{fl}}}+\frac{t_{\mathrm{fr}}{\mathrm{\ω}}_{m\_\mathrm{fr}}}{{\mathrm{\η}}_{\mathrm{fr}}}+\frac{t_{\mathrm{rl}}{\mathrm{\ω}}_{m\_\mathrm{fl}}}{{\mathrm{\η}}_{\mathrm{rl}}}+\frac{t_{\mathrm{rr}}{\mathrm{\ω}}_{m\_\mathrm{rr}}}{{\mathrm{\η}}_{\mathrm{rr}}})\mathrm{dt}$

Wherein, t_fl、t_fr、t_rl、t_rrIt is respectively the near front wheel, off-front wheel, left rear wheel, the torque of off hind wheel, ω_{m_fl}、ω_{m_fr}、 ω_{m_rl}、ω_{m_rr}For not Wei the near front wheel, off-front wheel, left rear wheel, off hind wheel rotating speed, η_fl、η_fr、η_rl、η_rrBe respectively the near front wheel, Off-front wheel, left rear wheel, the operating efficiency of off hind wheel motor, c is the total time of given cycle operating mode；

Try to achieve as car load instantaneously total power consumption e_comThe torque t of the near front wheel, off-front wheel, left rear wheel, off hind wheel when minimum_fl、t_fr、 t_rl、t_rr, and corresponding wheel is distributed in this torque.

As a kind of preferably, can calculated in advance obtain in different speeds v, different left and right sidesing driving wheel torque differences δ t and not With car load requirement drive torque t_reqUnder, instantaneous energy consumption is assigned to the level of torque of each wheel when minimum, and result is compiled into distribution Rule list, can obtain needing to be assigned to the torque value of each wheel by consulting this allocation rule table.

In addition, in the assigning process of torque, the car load requirement drive torque t that driver determines will be maintained_reqKeep not Become, i.e. t_req=t_fl+t_fr+t_rl+t_rr.The motor of each wheel simultaneously in order that energy-saving effect becomes apparent from, should be made when torque distributes Operating point all falls within high efficient district.That is, motor operating point should be changed by the energy-saving effect that turning energy-conservation torque distribution brings, motor effect Rate declines the excessive power drain leading to and offsets, and such turning energy-conservation torque distribution just has essential meaning.For this reason, the present invention is each Wheel torque distributes the mechanical efficiency that when considering torque distribution in main control algorithm, the change of motor operating point leads to and changes to car load The impact of energy-saving potential, that is, according to speed v, left and right sidesing driving wheel torque differences δ t and car load requirement drive torque t_reqSize, in wink When the minimum each wheel torque allocation rule table of energy consumption in linear interpolation go out each wheel torque distribution numerical value: t_fl、t_fr、t_rlAnd t_rr.

As shown in figure 3, when instantaneous energy consumption is minimum, each wheel torque value distribution method is as follows:

The first step, according to assembly characteristic and automobile running working condition feature, determines automobile speed v excursion 0～v_max, turn Square demand t_reqExcursion 0～t_{req_max}, left and right sidesing driving wheel torque differences δ t excursion-δ t_max～δ t_max, single-wheel torque t_e That is, t_fl、t_fr、t_rlAnd t_rrExcursion-t_{ε_max}～t_{ε_max}

Second step, calculates vehicle wheel rotational speed according to following formula, adopts wheel hub motor direct drive of wheel in this example, so wheel speed etc. In motor speed:

${\mathrm{\ω}}_m=\frac{v}{r_w}$

Wherein r_wFor vehicle wheel roll radius.

3rd step, by discrete for each variable for arithmetic progression.

4th step, by vehicle wheel rotational speeds scope 0～ω_{m_max}Discrete turn to arithmetic progression ω_m(n), n=1...n, tolerance For 100r/min, i.e. ω_m(1)=0r/min, ω_m(2)=100r/min, ω_m(3)=200r/min ..., ω_m(n)= [ω_{m_max}], wherein

5th step, by requirement drive torque excursion 0～t_{req_max}Discrete turn to arithmetic progression t_req(m), m= 1...m, tolerance is 10nm, i.e. t_req(1)=0nm, t_req(2)=10nm, t_req(3)=20nm ..., t_req(m)=[t_{req_max}], Wherein

6th step, by left and right sidesing driving wheel torque differences excursion-δ t_max～δ t_maxDiscrete turn to arithmetic progression δ t (i), I=1...i, tolerance is 10nm, i.e. δ t (1)=[- δ t_max], δ t (2)=([- δ t_max]+10) nm ...,..., δ t (i)=[δ t_max], wherein $i=\frac{\left[2\mathrm{\δ}{t}_{\max }\right]}{10}.$

7th step, by the near front wheel torque range-t_{ε_max}～t_{ε_max}Discrete turn to arithmetic progression t_fl(j), j=1...j, public Difference is 10nm, i.e. t_fl(1)=[- t_{e_max}], t_fl(2)=([t_{e_max}]+10) nm ...,..., t_fl(j)= [t_{e_max}], wherein $j=\frac{\left[2t_{e\_\max }\right]}{10}.$

8th step, by off-front wheel torque range-t_{ε_max}～t_{ε_max}Discrete turn to arithmetic progression t_fr(k), k=1...k, public Difference is 10nm, i.e. t_fr(1)=[- t_{e_max}], t_fr(2)=([t_{e_max}]+10) nm ...,..., t_fr(k) =[t_{e_max}], wherein $k=\frac{\left[2t_{e\_\max }\right]}{10}.$

9th step, determines the torque relationship of the near front wheel and left rear wheel, and the torque relationship of off-front wheel and off hind wheel.Due to Distribute between the between centers of torque and wheel and must be fulfilled for following two equation:

t_req=t_fl+t_fr+t_rl+t_rr

δ t=t_fl+t_rl-t_fr-t_rr

That is, should meet during torque distribution simultaneously not change total car load demand torque, realize left and right wheels Differential Driving simultaneously Realize turning Energy Saving Control.Above simultaneous, two formulas can calculate both sides wheel torque relational expression:

t_fl+t_rl=(t_req+δt)/2

t_fr+t_rr=(t_req-δt)/2

Next the torque t according to each wheel hub motor determining_fl、t_fr、t_rlAnd t_rr, and rotational speed omega_{m_fl}、ω_{m_fr}、 ω_{m_rl}And ω_{m_rr}Consult motor map figure, obtain operating efficiency η of each wheel hub motor_fl、η_fr、η_rlAnd η_rr, using following public affairs Formula calculates car load instantaneously total power consumption e_com:

$e_{\mathrm{com}}=\underset{0}{\overset{c}{\&integral;}}(\frac{t_{\mathrm{fl}}{\mathrm{\ω}}_{m\_\mathrm{fl}}}{{\mathrm{\η}}_{\mathrm{fl}}}+\frac{t_{\mathrm{fr}}{\mathrm{\ω}}_{m\_\mathrm{fr}}}{{\mathrm{\η}}_{\mathrm{fr}}}+\frac{t_{\mathrm{rl}}{\mathrm{\ω}}_{m\_\mathrm{fl}}}{{\mathrm{\η}}_{\mathrm{rl}}}+\frac{t_{\mathrm{rr}}{\mathrm{\ω}}_{m\_\mathrm{rr}}}{{\mathrm{\η}}_{\mathrm{rr}}})\mathrm{dt}$

Wherein c is the total time of given cycle operating mode.

Tenth step: judge whether k=k sets up.It is then to enter the 11st step, no, then return the 8th step after k increases by 1, that is, Off-front wheel torque increases e under this operating mode of 10nm cycle calculations_com；

11st step: judge whether j=j sets up.It is then to enter the 12nd step, no, then return the 7th step after j increases by 1, I.e. the near front wheel torque increases e under this operating mode of 10nm cycle calculations_com；

12nd step: so far under current working, that is, in a certain speed v, certain carload demand torque t_req, a certain left and right Under wheel drive torque differences instruction δ t, by contrasting allocative decision between above-mentioned 7th step to the 11st step various δ t differential torque wheel Under car load instantaneously total power consumption e_com, as acquirement e_comWhen being wherein minimum, between corresponding torque wheel, allocative decision is current working Allocation rule between lower torque wheel；

13rd step: judge whether i=i sets up.It is then to enter the 14th step, no, then return the 6th step after i increases by 1, I.e. left and right wheels driving torque difference instruction δ t increases e under this operating mode of 10nm cycle calculations_com；

14th step: judge whether m=m sets up.It is then to enter the 15th step, no, then return the 5th step after m increases by 1, Car load demand torque t_reqIncrease e under this operating mode of 10nm cycle calculations_com；

15th step: so far under current rotating speed, that is, under a certain speed v, by above-mentioned 5th step of contrast to the 14th Walk various car load demand torque t_reqCar load under two between centers allocative decisions instantaneously total power consumption e_com, as acquirement e_comIt is wherein minimum When corresponding torque between centers allocative decision be current vehicle speed under torque between centers allocation rule；

16th step: judge whether n=n sets up.It is then to enter the 17th step, no, then return the 4th step after n increases by 1, I.e. motor speed ω_mIncrease e under this operating mode of 100r/min cycle calculations_com；

17th step: so far just obtain any operating mode, i.e. any rotational speed omega_m, any car load demand torque t_reqWith any Each wheel torque allocation rule under left and right wheels driving torque difference δ t, this rule ensure that car load total power consumption e_comMinimum.Circulation is sought Excellent algorithm terminates.

In a word, the present invention has formulated each rotation moment optimal distribution control method for the purpose of energy-conservation according to Fig. 3, by from Line circulates optimizing, and the instantaneous energy consumption for the purpose of having formulated for the also energy-conservation of intended application vehicle establishment is minimum respectively to take turns torque Allocation rule table, is cured to this rule list in car load drive control device internal memory, by according to Fig. 2 calculated left and right in real time Wheel drive torque differences and car load demand torque instruction and current vehicle speed information, can be very easily in the way of tabling look-up online Obtain the minimum each wheel torque instruction of car load power consumption under current working, in order to control vehicle traction to travel and turning Differential Driving, Thus realizing turning power saving function.The method has significantly ageing and Global Optimality, possesses extraordinary practical application It is worth.

Although embodiment of the present invention is disclosed as above, it is not restricted to listed in specification and embodiment With, it can be applied to various suitable the field of the invention completely, for those skilled in the art, can be easily Realize other modification, therefore under the universal being limited without departing substantially from claim and equivalency range, the present invention does not limit In specific details with shown here as the legend with description.

Claims (9)

1. a kind of minimum wheel torque distribution method of instantaneous energy consumption is it is characterised in that comprise the following steps:

Step one, travel speed v obtaining automobile by sensor measurement, steering wheel angle δ_swAnd yaw velocity

Step 2, use equation below, calculate the differential torque between the driving wheel of the left and right sides

$\mathrm{\δ}t={\mathrm{mv}}^2\frac{{\mathrm{\δ}}_{sw}{l}_r{r}_w}{i_s{d}_{t}l}$

Wherein, m is vehicle mass；V is travel speed；δ_swFor steering wheel angle；r_wFor vehicle wheel roll radius；i_sFor steering Angular gear ratio；L is vehicle wheel base；l_rDistance for barycenter to rear axle；d_tFor automobile wheel track；

Step 3, in current demand driving torque t_req, under current driving speed v and current differential torque δ t operating mode, adopt with Lower formula calculates car load instantaneously total power consumption e_com

$e_{com}=\underset{0}{\overset{c}{\&integral;}}(\frac{t_{fl}{\mathrm{\ω}}_{m\_fl}}{{\mathrm{\η}}_{fl}}+\frac{t_{fr}{\mathrm{\ω}}_{m\_fr}}{{\mathrm{\η}}_{fr}}+\frac{t_{rl}{\mathrm{\ω}}_{m\_rl}}{{\mathrm{\η}}_{rl}}+\frac{t_{rr}{\mathrm{\ω}}_{m\_rr}}{{\mathrm{\η}}_{rr}})dt$

Wherein, t_fl、t_fr、t_rl、t_rrIt is respectively the near front wheel, off-front wheel, left rear wheel, the torque of off hind wheel, ω_{m_fl}、ω_{m_fr}、 ω_{m_rl}、ω_{m_rr}For not Wei the near front wheel, off-front wheel, left rear wheel, off hind wheel rotating speed, η_fl、η_fr、η_rl、η_rrBe respectively the near front wheel, Off-front wheel, left rear wheel, the operating efficiency of off hind wheel motor, c is the total time of given cycle operating mode；

Try to achieve as car load instantaneously total power consumption e_comThe torque t of the near front wheel, off-front wheel, left rear wheel, off hind wheel when minimum_fl、t_fr、t_rl、 t_rr, and corresponding wheel is distributed in this torque.

2. the minimum wheel torque distribution method of instantaneous energy consumption according to claim 1 is it is characterised in that in step 2, Before calculating the differential torque between two side drive wheel, calculate side acceleration first with equation below

$a_y=\frac{v^2}{r}\≈\frac{v^2{\mathrm{\δ}}_{sw}}{i_{s}l}$

And judge whether side acceleration is more than 0.6g, wherein, g is acceleration of gravity, and r is vehicle turn radius；

If so, then make the differential torque δ t=0 between two side drive wheel, and carry out step 3；

If it is not, then proceeding step 2.

3. the minimum wheel torque distribution method of instantaneous energy consumption according to claim 2 is it is characterised in that in step 2, After being calculated the differential torque between two side drive wheel, calculate preferable yaw velocity using equation below

${\stackrel{\·}{\mathrm{\ψ}}}_r=\frac{{\mathrm{v\δ}}_{sw}}{i_{s}l(1+k_w{v}^2)}$

Wherein, k_wFor stability of automobile factor；

And judge yaw velocityWhether more than preferable yaw velocity

If it is not, then keeping the differential torque δ t being calculated between two side drive wheel constant；

If so, then show that the differential torque that a upper controlling cycle introduces makes automobile be in ovdersteering, therefore utilize equation below pair Differential torque is modified

$\mathrm{\δ}t\left(h\right)=\mathrm{\δ}t(h-1)+p\[\frac{{\mathrm{v\δ}}_{sw}}{i_{s}l(1+k_w{v}^2)}-\stackrel{\·}{\mathrm{\ψ}}\]$

Wherein δ t (h-1) is the differential torque of a upper controlling cycle output, and δ t (h) is the calculated difference of this controlling cycle Dynamic torque, h is controlling cycle sequence number, and p is proportionality coefficient.

4. the minimum wheel torque distribution method of the instantaneous energy consumption according to Claims 2 or 3 is it is characterised in that step 2 In be calculated differential torque δ t after, judge that whether δ t is more than Automobile Maximum output torque t_max；If so, then make δ t=t_max； If otherwise maintaining δ t constant.

5. the minimum wheel torque distribution method of instantaneous energy consumption according to claim 4 is it is characterised in that step 3 includes Below step by step:

A) following formula is utilized to calculate vehicle wheel rotational speed

${\mathrm{\ω}}_m=\frac{v}{r_w}$

Wherein r_wFor vehicle wheel roll radius；

B) utilize equation below, calculate the torque relationship of the near front wheel and left rear wheel, and the torque relationship of off-front wheel and off hind wheel

t_fl+t_rl=(t_req+δt)/2

t_fr+t_rr=(t_req-δt)/2

C) in current demand driving torque t_req, under current driving speed v and current differential torque δ t operating mode, car load is instantaneously total Power consumption e_comIt is with regard to the near front wheel torque t_flWith off-front wheel torque t_frTwo-dimensional function, calculate described instantaneously total power consumption e_com's Minimum of a value e_{com_min}, and corresponding the near front wheel torque t_fl, left rear wheel torque t_rl, off-front wheel torque t_fr, off hind wheel torque t_rr, And corresponding wheel is distributed in corresponding torque.

6. the minimum wheel torque distribution method of instantaneous energy consumption according to claim 5 is it is characterised in that in step c), The near front wheel torque range is carried out discrete, obtain some grades of the near front wheel torque, the torque range of off-front wheel is carried out discrete, obtain To some grades of off-front wheel torque, calculate instantaneously total in the case of the near front wheel torque not at the same level and off-front wheel torque not at the same level respectively Power consumption e_com, and find out its minimum of a value e_{com_min}Corresponding the near front wheel torque t_fl, left rear wheel torque t_rl, off-front wheel torque t_fr, right Rear wheel torque t_rr, and corresponding wheel is distributed in corresponding torque.

7. the minimum wheel torque distribution method of instantaneous energy consumption according to claim 6 is it is characterised in that by left front rotation Square scope-t_{e_max}～t_{e_max}Discrete turn to arithmetic progression t_fl(j), j=1...j, tolerance is 10nm, i.e. t_fl(1)=[- t_{e_max}], t_fl(2)=([t_{e_max}]+10) nm ...,..., t_fl(j)=[t_{e_max}], wherein

By off-front wheel torque range-t_{e_max}～t_{e_max}Discrete turn to arithmetic progression t_fr(k), k=1...k, tolerance is 10nm, that is, t_fr(1)=[- t_{e_max}], t_fr(2)=([t_{e_max}]+10) nm ...,..., t_fr(k)=[t_{e_max}], its In

8. the minimum wheel torque distribution method of the instantaneous energy consumption according to any one of claim 5-7 it is characterised in that Vehicle wheel rotational speeds scope, requirement drive torque excursion, left and right sidesing driving wheel torque differences excursion are carried out discrete, obtain The vehicle wheel rotational speeds ω of some series_m(n), n=1...n, the requirement drive torque t of some series_req(m), m=1...m and Left and right sidesing driving wheel torque differences δ t (i) of some series, i=1...i, and the vehicle wheel rotational speeds under current working, demand are driven Dynamic torque, left and right sidesing driving wheel torque differences are rounded to immediate series.

9. the minimum wheel torque distribution method of instantaneous energy consumption according to claim 8 is it is characterised in that rotate wheel Velocity interval 0～ω_{m_max}Discrete turn to arithmetic progression ω_m(n), n=1...n, tolerance is 100r/min, i.e. ω_m(1)=0r/ Min, ω_m(2)=100r/min, ω_m(3)=200r/min ..., ω_m(n)=[ω_{m_max}], whereinAnd Work as ω_m(n)≤ω_m＜ ω_m(n+1), when, make ω_m=ω_m(n)；

By requirement drive torque excursion 0～t_{req_max}Discrete turn to arithmetic progression t_req(m), m=1...m, tolerance is 10nm, I.e. t_req(1)=0nm, t_req(2)=10nm, t_req(3)=20nm ..., t_req(m)=[t_{req_max}], wherein And work as t_req(m)≤t_req＜ t_req(m+1), when, make t_req=t_req(m)；

By left and right sidesing driving wheel torque differences excursion-δ t_max～δ t_maxDiscrete turn to arithmetic progression δ t (i), i=1...i, public Difference is 10nm, i.e. δ t (1)=[- δ t_max], δ t (2)=([- δ t_max]+10) nm ...,..., δ t (i)=[δ t_max], whereinAnd as δ t (i)≤δ t ＜ δ t (i+1), make δ t=δ t (i).