CN107199884B - It is averaged the torque distribution method of slippage rate for reducing axle - Google Patents
It is averaged the torque distribution method of slippage rate for reducing axle Download PDFInfo
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- CN107199884B CN107199884B CN201710315610.4A CN201710315610A CN107199884B CN 107199884 B CN107199884 B CN 107199884B CN 201710315610 A CN201710315610 A CN 201710315610A CN 107199884 B CN107199884 B CN 107199884B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K17/00—Arrangement or mounting of transmissions in vehicles
- B60K17/34—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles
- B60K17/348—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K17/00—Arrangement or mounting of transmissions in vehicles
- B60K17/34—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles
- B60K17/356—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles having fluid or electric motor, for driving one or more wheels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K17/00—Arrangement or mounting of transmissions in vehicles
- B60K17/34—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles
- B60K17/358—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles all driven wheels being steerable
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- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Arrangement And Driving Of Transmission Devices (AREA)
Abstract
It is averaged the torque distribution method of slippage rate the invention discloses a kind of for reducing axle, comprising the following steps: firstly, initialization register；Step 1: reading multiple signals of vehicles that sensor measurement obtains；Step 2: judging whether vehicle turns；Step 3: calculating the slippage rate of each sampling instant left and right sidesing driving wheel in real time；Step 4: the best slippage rate of the outer driving wheel of identification；Step 5: the longitudinal rigidity of the outer driving wheel of estimation；Step 6: judging whether driving wheels skid；Step 7: calculating the differential torque between left and right sidesing driving wheel；Step 8: carrying out torque distribution to two driving wheels under current demand driving torque；Step 9: exporting two rear wheel drive torques according to calculated result.In automobile turning, the average slippage rate using the drive shaft of torque distribution method rear vehicle provided by the present invention is lower, and the drive efficiency of driving wheel is higher, improves vehicle handling quality.
Description
Technical field
The present invention relates to the torque distribution methods of driving wheel when automobile turning, in particular to a kind of for reducing axle shaft
The torque distribution method of average slippage rate.
Background technique
The characteristics of each wheel drive torque of Electric Motor Wheel independent driving automobile can be distributed arbitrarily brings better than orthodox car
Dynamic property, maneuverability, stability techniques advantage.Furthermore the electronic integrated skill in chassis is arranged and is easily achieved on its flexible chassis
Art feature becomes the following Development of Electric Vehicles.However one kind as electric car, due to the bottleneck of battery technology, equally
It is set to have the short problem of continual mileage.Therefore, to realize the better economy of vehicle, how driving torque, which will distribute, to mention
Before high entirety drive efficiency makes a breakthrough as battery technology, it is necessary to the problem of being paid attention to.
For Electric Motor Wheel independent driving automobile, many torque distribution methods have been proposed at present.According to torque distribution
Purpose, these methods can be mainly divided into three classes.One kind is to improve the mobility of automobile, that is, under identical driver input,
This kind of torque distribution method can reduce the turning radius of vehicle, to realize quick excessively curved.One kind is to improve the stabilization of automobile
Property, i.e., under identical driver input, this kind of torque distribution method can reduce vehicle centroid side drift angle, reduce vehicle unstability
Trend, keep the stabilization of vehicle driving.It is to improve the economy of automobile there are also one kind, i.e., at the same conditions, this kind turns
Square distribution method can reduce vehicle turning resistance, increase rolling motion in vehicle, the energy consumption of automobile is reduced, to reach energy-efficient
Purpose.The core of such method is to be calculated using Vehicular linear two degrees of freedom reference model by target of ideal yaw velocity
The direct sideway moment of couple out, to carry out the torque distribution between each wheel.For electric car, the change of motor operating point is further accounted for
The influence of change and regenerative braking to overall energy consumption.However, the above torque distribution method is all based on greatly auto model
Feedback control has ignored influence of the torque distribution for wheel slip rate, leads to additional power loss.Therefore, the present invention will
According to the variation of Ackermann steer angle tire characteristics, the torque distribution between driving wheel is carried out, is averaged slippage rate, is subtracted with reducing the axle
Reactive loss when small driving improves the drive efficiency of axle, under the premise of not changing driving trace, reduces automobile turning energy
Consumption；Or in the case where not increasing power demand, the excessively curved speed of vehicle is improved.Present invention could apply to In-wheel motor drivings
Electric car, be equally applicable for driving torque can left and right wheels independently distribute traditional combustion engine driving automobile.
Summary of the invention
Distribution method between the torque wheel of automobile when the present invention provides a kind of for turning, the purpose is to reduce drive shaft
Average slippage rate, improves the drive efficiency of driving wheel, in the case where not increasing power demand, improves the excessively curved speed of vehicle.
To achieve the above object, technical solution provided by the invention are as follows:
It is a kind of to be averaged the torque distribution method of slippage rate for reducing axle, which comprises the following steps:
Step 1: carrying out Initialize installation to register, it iskoInitial value is assigned, q=0, flag=1 are set
Wherein,For the best slippage rate of the outer driving wheel of Ackermann steer angle, koFor the outer driving wheel of Ackermann steer angle
Longitudinal rigidity, q are a counters, and flag is skidding flag bit.
Step 2: the signals of vehicles obtained by sensor measurement is read, such as travel speed V, the steering wheel angle of vehicle
δsw, left and right sidesing driving wheel rotational speed omegai(i=l, r indicate left driving wheel and right driving wheel, similarly hereinafter) and core wheel speed vi, left and right drive
The driving torque T of driving wheelri
And judge whether vehicle turns, i.e. δsw≥δsw0It is whether true, wherein δsw0To consider that steering-wheel play is set inside
A small angle tower value；
If so, continuing step 3；
If it is not, then return step two.
Step 3: calculating the slippage rate of left and right driving wheel in real time in each sampling instant t using following formula
Wherein, siFor the slippage rate of driving wheel, rwFor the rolling radius of wheel, ignore the shadow to vehicle wheel roll radius here
It rings, it is believed that the rolling radius of left and right driving wheel is identical.
Step 4: calling the best slippage rate of the outer driving wheel of best slippage rate identification module identification
Step 5: calling the longitudinal rigidity k of the outer driving wheel of longitudinal tire stiffness estimation block estimationo。
Step 6: calculating the differential torque between left and right sidesing driving wheel using following formula
Wherein,For the best slippage rate of the outer driving wheel of Ackermann steer angle, such as: when vehicle is turned right,When
When vehicle turns left,soFor the current slippage rate of driving wheel outside Ackermann steer angle, such as: when vehicle is turned right, so=sl, when
When vehicle turns left, so=sr；koFor the longitudinal rigidity of the outer driving wheel of Ackermann steer angle, such as: when vehicle is turned right, ko=kl, when
When vehicle turns left, ko=kr；TreqFor the aggregate demand driving torque of vehicle, Treq=Trl+Trr；TaddConstant is corrected for differential torque；
Q is a counter, subtracts 1 to carry out the current control period number of torque distribution, specifically, when first control period, q
=0, when n-th of control period, q=n-1.
Step 7: keeping the aggregate demand driving torque of vehicle constant, according to the following formula, torque point is carried out to two driving wheels
Match:
To=0.5 (Treq+ΔT)
Ti=0.5 (Treq-ΔT)
Wherein, ToThe torque of driving wheel, T outside when to turniThe torque of interior driving wheel when to turn.
Step 8: returning and making counter q from increasing 1, circulation executes step 6 to step 8.
Preferably, in step 4, best slippage rate identification module need to calculate two variables first with following formula
Wherein, uiReal-time attachment coefficient when for vehicle driving between driving wheel and ground, IwFor the rotary inertia of wheel,
κiFor real-time attachment coefficient uiTo the derivative of time,For slippage rate siTo the derivative of time.
Secondly, and when judging any time tWhether set up simultaneously with flag=1；
If so, illustrating the wheel-slip, skidding flag bit flag=0 is exported.Tire slippage rate at this time is the drive
The best slippage rate of driving wheel, i.e.,
If it is not, then illustrate that the wheel does not skid, skidding flag bit flag=1 is exported, it is original in holding register
It is constant；
Finally, the best slippage rate of two driving wheel China and foreign countries driving wheels of outputWith skidding flag bit flag.
Preferably, best slippage rate takes in true tire attachment characteristic curve and corresponds to trackslipping for peak value longitudinal force of tire
Rate, the rate score that trackslips corresponding with the simplified broken line inflection point of tire attachment characteristic are close.
Preferably, in step 5, longitudinal tire stiffness estimation block is by recurrent least square method (RLS) Lai Shixian
The identification of the longitudinal rigidity of driving wheel, export and update the longitudinal rigidity k of outer driving wheelo。
Preferably, longitudinal rigidity takes tire attachment characteristic to simplify the slope that segmented line model middle polyline crosses origin oblique line,
It is close in the slope numerical value of its linearly interval with true tire attachment characteristic curve.
Preferably, in step 6, after calculating the differential torque between left and right sidesing driving wheel, sentenced by skidding flag bit flag
Whether disconnected driving wheel skids；
If flag=0, illustrate that driving wheel skids, then enables the differential torque Δ T=0 between two driving wheels, and start and lead
Gravitation control system inhibits wheel-slip；
If flag=1, illustrate that driving wheel does not skid, then keeps the differential torque Δ T being calculated between two driving wheels
It is constant.
Preferably, the T in the formula in step 6addQ is the correction amount of differential torque, wherein torque modification constant
TaddIt integrates and is determined according to the longitudinal rigidity of identification and tire attachment characteristic curve in the difference of the slope of its linearly interval,
The setting of its maximum value will avoid the addition of correction amount that driving wheel is caused to skid.
Preferably, when vehicle is turned right, the driving torque for distributing to left and right sidesing driving wheel is respectively
Trl=T0=0.5 (Treq+ΔT)
Trr=Ti=0.5 (Treq-ΔT)
Wherein, TrlFor the torque of left driving wheel, TrrFor the torque of right driving wheel.
Preferably, when vehicle turns left, the driving torque for distributing to left and right sidesing driving wheel is respectively
Trr=T0=0.5 (Treq+ΔT)
Trl=Ti=0.5 (Treq-ΔT)
Wherein, TrlFor the torque of left driving wheel, TrrFor the torque of right driving wheel.
The beneficial effects of the present invention are:
The present invention guarantee driving wheel it is non-slip under the premise of, when sensor detect steering wheel angle input, vehicle into
It when the state of row turning driving, is redistributed by the driving torque of left and right sidesing driving wheel, generates the torque differences of inside and outside wheel, thus
Generate additional yaw moment.Under the premise of carrying out identical working condition tests with the vehicle for not applying control, the present invention is used
The average slippage rate of the drive shaft of the vehicle of institute's providing method is lower, and the drive efficiency of driving wheel is higher, is not changing traveling
Under the premise of track, automobile turning energy consumption is reduced；Or in the case where not increasing power demand, the excessively curved speed of vehicle is improved.
Present invention could apply to hub motor driven electric vehicle, being equally applicable for driving torque can the tradition independently distributed of left and right wheels
Internal combustion engine drives automobile.
Detailed description of the invention
Fig. 1 is tire attachment characteristic rough schematic view.
Fig. 2 inside and outside driving wheel torque distribution principle schematic diagram when being turning.
Fig. 3 is described to be averaged the torque distribution method general flow chart of slippage rate for reducing axle.
Fig. 4 is best slippage rate identification module control method flow chart.
Fig. 5 is longitudinal tire stiffness estimation block control method flow chart.
Specific embodiment
Present invention will be described in further detail below with reference to the accompanying drawings, to enable those skilled in the art referring to specification text
Word can be implemented accordingly.
As shown in Figure 1, the block curve in figure is the tire attachment characteristic curve under a certain vertical load.Because only that
Under conditions of keeping well attached between tire and ground, torque distribution is just meaningful.Therefore, use of the present invention
It in reducing the be averaged torque distribution method of slippage rate of axle is carried out in the linearly interval of tire, i.e., beats the area of oblique line in figure
Domain.As shown in Figure 1, it is of the present invention for reduce axle be averaged slippage rate torque distribution method by this nonlinear wheel
Tire attachment characteristic curve is simplified to cross (the i.e. tire attachment of peak adhesion coefficient by an oblique line for crossing origin of linear zone and one
Characteristic curve vertex) horizontal line composition broken line, i.e., shown in the dotted line in figure.Heretofore described longitudinal tire stiffness is exactly
Refer to that the simplification tire attachment characteristic curve in the slope of linear zone oblique line, repeats no more hereinafter.
As shown in Fig. 2, when the vehicle is turning, due to redistributing for vertical load, the longitudinal rigidity of outer driving wheel tire
Greater than the longitudinal rigidity of interior driving wheel tire.If driving torque mean allocation between left and right sidesing driving wheel, the cunning of interior driving wheel
Slippage rate more than outer driving wheel, interior driving wheel are easier to the phenomenon that having skidded by rate of rotation.If being re-started to left and right sidesing driving wheel
Torque distribution, i.e., the longitudinal rigidity of driving wheel is gradient in addition, the appropriate driving torque for increasing outer driving wheel, while waiting big subtract
The driving torque of small interior driving wheel, then the driving torque of outer driving wheel will change along oblique line A-A', the slippage rate liter of outer driving wheel
Height, and the driving torque of interior driving wheel will change along oblique line B-B', the slippage rate of interior driving wheel reduces.But due to outer driving
The longitudinal rigidity of wheel is greater than the longitudinal rigidity of interior driving wheel, and the slippage rate incrementss of outer driving wheel are less than the slippage rate of interior driving wheel
Reduction amount, therefore, the average slippage rate of the drive shaft are to reduce.That is, of the present invention flat for reducing axle
The longitudinal direction that the torque distribution method of equal slippage rate can reduce driving wheel is trackslipped, and is reduced wheel slip bring energy loss, is mentioned
High driving efficiency.
As shown in figure 3, of the present invention be averaged the torque distribution control method main-process stream of slippage rate for reducing axle
It is as follows.
Step 1 carries out Initialize installation to register, it may be assumed that bekoInitial value is assigned, q=0, flag=1 are set.
Wherein,For the best slippage rate of the outer driving wheel of Ackermann steer angle, koFor the outer driving wheel of Ackermann steer angle
Longitudinal rigidity, q are a counters, and flag is skidding flag bit.
Step 2: the signals of vehicles obtained by sensor measurement is read, such as travel speed V, the steering wheel angle of vehicle
δsw, left and right sidesing driving wheel rotational speed omegai(i=l, r indicate left driving wheel and right driving wheel, similarly hereinafter.) and core wheel speed vi, or so
The driving torque T of driving wheelri,
And judge whether vehicle turns, i.e. δsw≥δsw0It is whether true, wherein δsw0To consider that steering-wheel play is set inside
A small angle tower value, can such as set δsw0=15 ° are an embodiment；
If so, continuing step 3；
If it is not, then return step two.
Step 3: calculating the slippage rate of left and right driving wheel in real time in each sampling instant t using formula (1):
Wherein, siFor the slippage rate of driving wheel, rwFor the rolling radius of wheel, viFor the core wheel speed of wheel, ignore here
Influence to vehicle wheel roll radius, it is believed that the rolling radius of left and right sidesing driving wheel is identical.
Step 4: calling best slippage rate identification module, the best slippage rate of outer driving wheel is identified
Step 5: calling longitudinal tire stiffness estimation block, the longitudinal rigidity k of outer driving wheel is estimatedo,
And judge whether driving wheels skid, i.e., whether flag=0 is true；
If so, illustrating that driving wheel skids, then Δ T=0, q=0, storesko, and start traction control system
(TCS), after inhibiting wheel-slip；
If it is not, illustrating that driving wheel does not skid, then step 6 is carried out.
Step 6: calculating the differential torque Δ T between left and right sidesing driving wheel using formula (2):
Wherein,For the best slippage rate of the outer driving wheel of Ackermann steer angle, such as: when vehicle is turned right,When
When vehicle turns left,soFor the current slippage rate of driving wheel outside Ackermann steer angle, such as: when vehicle is turned right, so=sl, when
When vehicle turns left, so=sr；koFor the longitudinal rigidity of the outer driving wheel of Ackermann steer angle, such as: when vehicle is turned right, ko=kl, when
When vehicle turns left, ko=kr；TreqFor the aggregate demand driving torque of vehicle, Treq=Trl+Trr；TaddConstant is corrected for differential torque；
Q is a counter, subtracts 1 to carry out the current control period number of torque distribution, specifically, when first control period, q
=0, when n-th of control period, q=n-1.
Step 7: keeping the aggregate demand driving torque of vehicle constant, different torques is distributed for two driving wheels.Two drivings
The torque distribution of wheel must satisfy following condition:
Treq=To+Ti (3)
Δ T=To-Ti (4)
Then, formula (5), (6) can be acquired, according to formula (5), (6), torque distribution is carried out to two driving wheels:
To=0.5 (Treq+ΔT) (5)
Ti=0.5 (Treq-ΔT) (6)
Wherein, ToThe driving torque of driving wheel, T outside when to turniThe driving torque of interior driving wheel when to turn.
It should be noted that the T in formula (2)addQ is the correction amount of differential torque Δ T, torque modification constant Tadd
Can integrate according to step 5 estimation longitudinal rigidity and tire attachment characteristic curve the slope of its linearly interval difference come
Determine, numerical value can not be excessive, in order to avoid due to correction amount addition and cause the skidding of driving wheel, need to be normal to torque modification
Number TaddNumerical value be defined.
Step 8: exporting rear wheel drive torque T according to formula (7), (8), (9), (10)rlAnd Trr。
When vehicle is turned right, the driving torque for distributing to left and right sidesing driving wheel is respectively
Trl=T0=0.5 (Treq+ΔT) (7)
Trr=Ti=0.5 (Treq-ΔT)
(8)
When vehicle turns left, the driving torque for distributing to left and right sidesing driving wheel is respectively
Trr=T0=0.5 (Treq+ΔT) (9)
Trl=Ti=0.5 (Treq-ΔT) (10)
Finally, returning and making counter q from increasing 1, circulation executes step 6 to step 9.
As shown in figure 4, it is of the present invention for reduce axle be averaged slippage rate torque distribution method in best cunning
The detailed process of rate of rotation identification module is as follows:
Step 1: to flag, κ,Progress Initialize installation, flag=1, κ=0,
Wherein, κ is derivative of the real-time attachment coefficient u to the time,It is slippage rate s to the derivative of time.
Step 2: the driving torque T of input left and right sidesing driving wheelri, rotational speed omegaiAnd slippage rate si。
Step 3: calculating κ in real time according to formula (14), (15)i(t)、
Firstly, according to Electric Motor Wheel rotary system dynamics it is found that
Wherein, uiReal-time attachment coefficient when for vehicle driving between driving wheel and ground, FZiIt is subject to for the driving wheel
Vertical load, IwFor the rotary inertia of wheel, κiFor real-time attachment coefficient uiTo the derivative of time,It is slippage rate to the time
Derivative.
Secondly, in the driving wheel angular acceleration of sampling instant tIt can be calculated according to formula (13):
Wherein, T is sampling step length.
Finally, due to which the recognizer is indifferent to κiWithSpecific value, be only concerned its symbol, therefore in formula (11)
Except the constant coefficient item before derivative.Then, in the κ of sampling instant ti(t) andIt can be calculated according to formula (14), (15):
Step 4: judgementAnd whether flag=1 is true.
If so, the driving wheel skids explanation at this time, skidding flag bit flag=0 is exported, tire slippage rate at this time is
The best slippage rate of the driving wheel, i.e.,Finally, the best slippage rate of the outer driving wheel in two driving wheels of output
If it is not, the driving wheel does not skid explanation at this time.If two driving wheels all do not skid, skidding mark is exported
Position flag=1, it is original in holding registerIt is constant, output
So far, best slippage rate identification module operation process terminates.
As shown in figure 5, for it is of the present invention for reduce axle be averaged slippage rate torque distribution method in tire
Longitudinal rigidity estimation block, the module are to realize that by recurrent least square method (RLS) method, the longitudinal rigidity of driving wheel is estimated
It calculates.Its detailed process is as follows:
Step 1: initialization go(1)、Po(1) and λ.
Wherein, goIt (1) is the longitudinal tire stiffness of the outer driving wheel of first sampling instant, Po(1) first sampling instant
Covariance, λ is forgetting factor.
Step 2: calculating the driving force F of outer driving wheel according to formula (16) in each sampling instanto(t)
Step 3: calculating deviation e according to formula (17) since second sampling instanto(t)
eo(t)=Fo(t)-so(t)·go(t-1) (17)
Step 4: calculating gain K according to formula (18) since second sampling instanto(t)
Ko(t)=Po(t-1)·so(t)·[λ+so(t)·Po(t-1)·so(t)]-1 (18)
Step 5: calculating covariance P according to formula (19) since second sampling instanto(t)
Po(t)=λ-1-Ko(t)·so(t)·λ-1·Po(t-1) (19)
Step 6: calculating longitudinal tire stiffness g according to formula (20)o(t)
go(t)=go(t-1)+Ko(t)·eo(t) (20)
Step 7: comparing go(t-1) and go(t),
If go(t-1) > go(t), then ko=go(t-1)；
Otherwise, ko=go(t)。
Step 8: updating and exporting the longitudinal tire stiffness k of outer driving wheelo。
Within the sampling time, step 2 is repeated to step 8, until the longitudinal tire stiffness of the outer driving wheel of output finally
ko。
So far, longitudinal tire stiffness estimation block operation process terminates.
Torque distribution method of the present invention is determining left and right sidesing driving wheel torque difference Δ T and is executing Differential Driving
In the process, the case where whether driving wheel skids fully considered.Once vehicle is during the turn because driving wheel skids
Easily unstability, torque distribution are not in all senses.Therefore, only adhere to good situation in guarantee driving wheel and ground
Under, it just can be carried out and of the present invention be averaged the torque distribution method of slippage rate for reducing axle.The present invention be directed to rear-wheels
Control method is distributed between a kind of torque wheel that independent drive vehicles use.In turning, go out from the tire characteristics of left and right sidesing driving wheel
Hair, the torque distribution between being taken turns according to the longitudinal rigidity of tire and slippage rate, trackslips to realize being averaged for the drive shaft
The reduction of rate improves the drive efficiency of the drive shaft, reduces tire due to bring energy loss of trackslipping.
Although the embodiments of the present invention have been disclosed as above, but its is not only in the description and the implementation listed
With it can be fully applied to various fields suitable for the present invention, for those skilled in the art, can be easily
Realize other modification, therefore without departing from the general concept defined in the claims and the equivalent scope, the present invention is simultaneously unlimited
In specific details and legend shown and described herein.
Claims (9)
1. a kind of be averaged the torque distribution method of slippage rate for reducing axle, which comprises the following steps:
Step 1: carrying out Initialize installation to register, it iskoInitial value is assigned, q=0, flag=1 are set
Wherein,For the best slippage rate of the outer driving wheel of Ackermann steer angle, koFor the longitudinal direction of the outer driving wheel of Ackermann steer angle
Rigidity, q are a counters, and flag is skidding flag bit；
Step 2: reading the signals of vehicles obtained by sensor measurement, travel speed V, steering wheel angle δ such as vehiclesw, it is left
The rotational speed omega of right driving wheeli, i=l, r indicate left driving wheel and right driving wheel, similarly hereinafter and core wheel speed vi, left and right sidesing driving wheel
Driving torque Tri
And judge whether vehicle turns, i.e. δsw≥δsw0It is whether true, wherein δsw0One set inside for consideration steering-wheel play
A small angle tower value；
If so, continuing step 3；
If it is not, then return step two；
Step 3: calculating the slippage rate of left and right driving wheel in real time in each sampling instant t using following formula
Wherein, siFor the slippage rate of driving wheel, rwFor the rolling radius of wheel, ignores the influence to vehicle wheel roll radius here, recognize
Rolling radius for left and right driving wheel is identical；
Step 4: calling the best slippage rate of the outer driving wheel of best slippage rate identification module identification
Step 5: calling the longitudinal rigidity k of the outer driving wheel of longitudinal tire stiffness estimation block estimationo；
Step 6: calculating the differential torque between left and right sidesing driving wheel using following formula
Wherein,For the best slippage rate of the outer driving wheel of Ackermann steer angle, such as: when vehicle is turned right,When a vehicle left side
When turning,soFor the current slippage rate of driving wheel outside Ackermann steer angle, such as: when vehicle is turned right, so=sl, work as vehicle
When left-hand rotation, so=sr, and require the current slippage rate s of the outer driving wheel of the Ackermann steer angle in the torque distribution methodoAlways small
In the best slippage rate of the outer driving wheel of Ackermann steer angleIt requires described to be averaged the torque of slippage rate for reducing axle
Distribution method is carried out in the linearly interval of tire；koFor the longitudinal rigidity of the outer driving wheel of Ackermann steer angle, such as: working as vehicle
When right-hand rotation, ko=kl, when vehicle turns left, ko=kr；TreqFor the aggregate demand driving torque of vehicle, Treq=Trl+Trr；TaddFor difference
Dynamic torque corrects constant；Q is a counter, subtracts 1 to carry out the current control period number of torque distribution, specifically, when the
When one control period, q=0, when n-th of control period, q=n-1；The differential torque of acquisition can reduce axle shaft
Average slippage rate, keep the drive efficiency of driving wheel higher, under the premise of not changing driving trace, automobile turning can be reduced
Energy consumption；
Step 7: keeping the aggregate demand driving torque of vehicle constant, according to the following formula, torque distribution is carried out to two driving wheels:
To=0.5 (Treq+ΔT)
Ti=0.5 (Treq-ΔT)
Wherein, ToThe torque of driving wheel, T outside when to turniThe torque of interior driving wheel when to turn；
Step 8: returning and making counter q from increasing 1, circulation executes step 6 to step 8.
2. torque distribution method according to claim 1, which is characterized in that in step 4, best slippage rate identification module
Two variables need to be calculated first with following formula
Wherein, uiReal-time attachment coefficient when for vehicle driving between driving wheel and ground, IwFor the rotary inertia of wheel, κiFor
Real-time attachment coefficient uiTo the derivative of time,For slippage rate siTo the derivative of time；
Secondly, and when judging any time tWhether set up simultaneously with flag=1；
If so, illustrating the wheel-slip, skidding flag bit flag=0 is exported；Tire slippage rate at this time is the driving wheel
Best slippage rate, i.e.,
If it is not, then illustrate that the wheel does not skid, skidding flag bit flag=1 is exported, it is original in holding registerIt is constant；
Finally, the best slippage rate of two driving wheel China and foreign countries driving wheels of outputWith skidding flag bit flag.
3. torque distribution method according to claim 1 or 2, it is characterised in that the best slippage rate takes true tire
The slippage rate that peak value longitudinal force of tire is corresponded in attachment characteristic curve, cunning corresponding with the simplified broken line inflection point of tire attachment characteristic
Rate of rotation numerical value is close.
4. torque distribution method according to claim 1, which is characterized in that in step 5, longitudinal tire stiffness estimates mould
Block is to export by the identification of the longitudinal rigidity of recurrent least square method (RLS) Lai Shixian driving wheel and update outer driving wheel
Longitudinal rigidity ko。
5. torque distribution method according to claim 1, it is characterised in that the longitudinal rigidity takes tire attachment characteristic
Simplify segmented line model middle polyline and cross the slope of origin oblique line, with true tire attachment characteristic curve its linearly interval slope
Numerical value is close.
6. torque distribution method according to claim 1, which is characterized in that in step 6, calculate between left and right sidesing driving wheel
Differential torque after, by skidding flag bit flag judge drive wheel whether skid；
If flag=0, illustrates that driving wheel skids, then enable the differential torque Δ T=0 between two driving wheels, and start tractive force
Control system inhibits wheel-slip；
If flag=1, illustrate that driving wheel does not skid, then keeps the differential torque Δ T being calculated between two driving wheels constant.
7. torque distribution method according to claim 1, which is characterized in that the T in formula in step 6addQ is poor
The correction amount of dynamic torque, wherein torque modification constant TaddIntegrate the longitudinal rigidity and tire attachment characteristic curve according to estimation
It is determined in the difference of the slope of its linearly interval, the setting of maximum value will avoid the addition of correction amount that driving wheel is caused to beat
It is sliding.
8. torque distribution method according to claim 1, which is characterized in that when vehicle is turned right, distribute to left and right driving
The driving torque of wheel is respectively
Trl=T0=0.5 (Treq+ΔT)
Trr=Ti=0.5 (Treq-ΔT)
Wherein, TrlFor the torque of left driving wheel, TrrFor the torque of right driving wheel.
9. torque distribution method according to claim 1, which is characterized in that when vehicle turns left, distribute to left and right driving
The driving torque of wheel is respectively
Trr=T0=0.5 (Treq+ΔT)
Trl=Ti=0.5 (Treq-ΔT)
Wherein, TrlFor the torque of left driving wheel, TrrFor the torque of right driving wheel.
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| CN110606088B (en) * | 2019-09-18 | 2020-08-18 | 北京理工大学 | Electric wheel drive anti-skid control strategy |
| CN111076951B (en) * | 2019-12-05 | 2021-09-10 | 江苏大学 | Method for testing steering slip ratio of tracked vehicle |
| CN113895445B (en) * | 2021-11-22 | 2024-01-05 | 吉林大学重庆研究院 | Parasitic power classification and unnecessary parasitic power calculation method for vehicle |
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