CN108275200A - A kind of electric wheel drive vehicle composite energy-saving servo steering device and its control method - Google Patents
A kind of electric wheel drive vehicle composite energy-saving servo steering device and its control method Download PDFInfo
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- CN108275200A CN108275200A CN201810217474.XA CN201810217474A CN108275200A CN 108275200 A CN108275200 A CN 108275200A CN 201810217474 A CN201810217474 A CN 201810217474A CN 108275200 A CN108275200 A CN 108275200A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0418—Electric motor acting on road wheel carriers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
- B60L15/2036—Electric differentials, e.g. for supporting steering vehicles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
- B62D5/046—Controlling the motor
- B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2220/00—Electrical machine types; Structures or applications thereof
- B60L2220/40—Electrical machine applications
- B60L2220/44—Wheel Hub motors, i.e. integrated in the wheel hub
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Power Engineering (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
- Power Steering Mechanism (AREA)
Abstract
The invention discloses a kind of electric wheel drive vehicle composite energy-saving servo steering devices, including：Including steering wheel, steering shaft, steering-wheel torque sensor, steering wheel angle sensor, assist motor, turbine and worm decelerator, rack and pinion steering gear, left steering drag link, right turn drag link, the near front wheel, left wheel hub motor, off-front wheel, right wheel hub motor, primal coordination control module, differential power-assisted steering control module, slippage rate control module and electric power steering control module.The invention also discloses a kind of control methods of electric wheel drive vehicle composite energy-saving servo steering device, including：Gathered data enters energy saving steering pattern, safe steering pattern and fail-safe mode according to monitoring data.
Description
Technical field
The present invention relates to automobile technical fields, and in particular to a kind of electric wheel drive vehicle composite energy-saving servo steering device
And its control method.
Background technology
Electric Motor Wheel independent driving automobile eliminates the transmission system of orthodox car, power directly by being mounted in wheel or
The wheel hub motor or wheel motor for taking turns side are provided to drive wheel.Electric wheel drive vehicle is simple in structure, saves space, is more easy to
Realize advanced vehicle dynamics integrated control.
Electric power steering (EPS) system realizes power-assisted, it can be achieved that with the adjustable power-assisted size of speed using assist motor, is existing
No matter orthodox car or electric vehicle use widest force aid system.But electric boosting steering system also has its own to lack
Point, the i.e. rotary inertia of assist motor acceleration and deceleration device can reduce dynamic response quality when big torque power-assisted demand, and there are sluggishnesses
With the response problem of overshoot, in addition assist motor running noise the more sensitive hand of driver can be also transmitted to by steering wheel
Portion influences driving sensation and quality, therefore EPS system can still excavate its energy-efficient potentiality at present.In addition at this stage for electricity
For motor-car, energy saving is its important research emphasis.In addition to this, electric boosting steering system then turns when steering motor fails
Reliable power-assisted can not be provided to system, for oversize vehicle, there is prodigious security risk.
Differential power-assisted steering (Differential Drive Assist Steering, DDAS) technology is based on Electric Motor Wheel
A kind of power steering new technology that independent driving automobile platform proposes.Differential power-assisted steering makes full use of electric wheel drive vehicle each
Wheel torque can independent control the characteristics of, the torque differences generated using left and right front-wheel difference torque realize the power-assisted to steering.
Differential servo steering system eliminates traditional servo steering system power-assisted output block, it is only necessary to be integrated in original in the form of software
Have in vehicle drive control device, it is compact-sized, it occupies little space, reduces cost and car mass differential power-assisted steering simultaneously exists
Turning resistance can be reduced while power-assisted, while the driving motor of two front-wheels being made to be operated in more efficient operating point, therefore energy
It is enough to save energy expenditure to a certain extent, improve electric vehicle continual mileage.But differential power-assisted steering is as a kind of indirect power-assisted
Steering mode in the big power torque demand of demand, such as pivot stud operating mode power-assisted performance and inferior quality, other road surface
Noise Mechanism caused by injustice can also influence the stationarity of the power-assisted square output of DDAS systems, while the EPS system that compares, DDAS
Tire wear can be increased when work to a certain extent.
Patent application 2016111665807 proposes a kind of the multi-mode steering system and controlling party of electric wheel drive vehicle
The rotor of electric boosted motor is coaxially connected by method, the system with steering shaft, increases the steering inertia of steering shaft, reduces big
There is sluggish and overshoot response problem in dynamic response quality when torque power-assisted demand.Simultaneously without deceleration mechanism, make required
Assist motor volume increases, and in addition the system does not consider the problems of steering energy consumption.
Invention content
The present invention has designed and developed a kind of electric wheel drive vehicle composite energy-saving servo steering device, is turned by differential power-assisted
Turning resistance is reduced to the combination with electric boosting steering system and reduction whole system energy consumption is realized in optimization motor operating point
Purpose.
The present invention has designed and developed a kind of control method of electric wheel drive vehicle composite energy-saving servo steering device, passes through
This control method realizes that the coordination to differential power-assisted steering and electric power steering controls, and automobile is total when effectively reducing steering
Energy consumption, the energy-efficient purpose of solid line.
Technical solution provided by the invention is：
A kind of electric wheel drive vehicle composite energy-saving servo steering device, including：
Steering wheel；
Steering shaft connects the steering wheel centre, and is passed in the installing angle sensor in the steering shaft and torque
Sensor；
Deceleration mechanism, output end connect the steering shaft；
Assist motor connects the input terminal of the deceleration mechanism；
Steering gear connects the steering shaft lower end, and connects vehicle by drag link respectively at the steering gear both ends
Wheel；
Electronic control unit, rotary angle transmitter, the torque sensor and vehicle CAN bus described in Electricity Federation；
Wherein, the electronic control unit includes primal coordination control device, motor-driven power steering control device, differential power-assisted
Steering control device and slippage rate control device；
Assist motor described in electric power steering control Electricity Federation；
Wheel hub motor in wheel described in slippage rate control device Electricity Federation.
Preferably, the deceleration mechanism is set as worm gear structure.
Preferably, the steering gear is rack pinion steering gear；
Wherein, the tooth sector of the rack pinion steering gear connects the lower end of the steering shaft；And
The rack of the rack pinion steering gear and tooth sector engaged transmission, and the rack connects the cross
Pull rod.
Preferably, the drag link is connected by ball stud with the knuckle of the wheel.
A kind of control method of electric wheel drive vehicle composite energy-saving servo steering device, using the transfer,
It is characterised in that it includes following steps：
Step 1: judging assist motor, if assist motor fails, electronic control unit enters fail safe
Control model；If assist motor normal operation, data acquisition, including yaw velocity ω are carried outr, speed v, barycenter lateral deviation
Angle beta, side slip angle speedWith coefficient of road adhesion μ；
Step 2: determining inhibited stably parameter value B according to the coefficient of road adhesion μ1、B2, and according to the stabilization
Domain boundary parameter value B1、B2Phase plane Calculation of Stability Region is carried out, ifWhen, then electronic control unit into
Enter energy saving steering pattern, ifWhen, then electronic control unit enters safe steering pattern；
Wherein, the energy saving steering pattern includes：
Monitor steering-wheel torque Tsw, speed v, steering wheel angle δswAnd total driving demand torque Tg；According to described turn
To disk corner δswThe different values with speed v's obtain differential power-assisted steering work weight coefficient by the first optimization object function
The initial value of difference of value k, and carry out the initial value k after data preparation is optimizedc；Wherein, optimization process makes the first optimization
Object function value is minimum；
First optimization object function is
In formula, T1For the motor output torque of the near front wheel；n1For the output rotating speed of the near front wheel；T2It is defeated for the motor of off-front wheel
Go out torque；n2For the output rotating speed of off-front wheel；a1、a2、a3Respectively weight coefficient；TtFor the output torque of assist motor；ntFor
The output rotating speed of assist motor；a1、a2、a3Respectively weight coefficient；λ1, λ2, λtRespectively left front turbin generator, off-front wheel motor with
And the efficiency of assist motor；
According to the initial value kcThe optimizing of work weight coefficient value k is carried out by the second optimization object function；Wherein,
In, optimization process keeps the second optimization object function value minimum；
Second optimization object function is
The constraint equation of work weight coefficient value k is c1kc≤k≤c2kc；
In formula, TgFor total driving moment that main coordinating control module goes out according to speed and target vehicle speed mathematic interpolation, TzFor difference
The differential torque of front-wheel needed for power-assisted that dynamic power-assisted steering control module institute decision goes out, b1, b2, btRespectively corresponding optimization power
Weight coefficient, c1And c2Respectively optimize border coefficient；
Determine the differential torque T of front-wheelzWith the control voltage signal needed for assist motor, according to the work weight coefficient value
K determines the differential torque Δ T of final output front-wheel power-assisted demandz, by total driving moment Tg, the output of differential booster steering controller
Required yaw moment distributes to two front-wheels, and is modified by skidding rate of rotation control device, and assist motor exports power-assisted
The diverted drive system mechanism of torque is acted on to steering wheel.
Preferably, the safe steering pattern includes：
Monitor steering-wheel torque Tsw, speed v, steering wheel angle δsw, according to the steering wheel angle δswIt is obtained with speed v
Ideal steering-wheel torque Tswd；
By the steering-wheel torque TswWith the ideal steering-wheel torque TswdDifference input electric power steering control dress
It sets, the control voltage signal of assist motor is calculated by fuzzy, and voltage signal is delivered to assist motor, export power-assisted
Torque.
Preferably, the fail safe steering pattern includes：
Monitor steering-wheel torque Tsw, speed v, steering wheel angle δswWith total driving demand torque TgWith according to the steering wheel
Corner δswIdeal steering-wheel torque T is obtained with speed vswd；
By the steering-wheel torque TswWith the ideal steering-wheel torque TswdDifference input differential power-assisted steering control dress
It sets, the differential moment values T of the front-wheel of demand is calculated by PIDz, and calculate the moment values of left and right front-wheel demand；
By the demand moment values of calculated the near front wheel and off-front wheel input respectively the slippage rate control device of each wheel into
Row is corrected, and revised front-wheel demand moment values are exported to wheel hub motor and are controlled.
Preferably,
Determine the differential torque T of front-wheelzIt is exported by differential power-assisted steering control device, the differential power-assisted steering control
Device processed uses PID controller；And
Determine that the control voltage signal needed for assist motor is exported by motor-driven power steering control device, the electricity
Dynamic power-assisted steering control device uses fuzzy controller.
Preferably, the differential torque Δ T of front-wheelzIt is calculated by the following formula：
In formula, Ti(i=1,2) it is respectively the near front wheel, off-front wheel output torque.
Preferably, being modified process to the skidding rate of rotation control device includes：
The slippage rate of each wheel is calculated in real time, while the best slippage rate of the wheel that when real-time estimation is each inscribes,
When the practical slippage rate of wheel is more than optimum wheel slippage rate under the moment, slippage rate control device is started to work, and is controlled by PID
Algorithm processed calculates output slippage rate control and corrects torque Txi(i=1,2), the wheel demand torque T after correctingsi(i=1,2)
Calculation formula is Tsi=Ti+Txi。
The present invention compared with prior art possessed by advantageous effect：
1, low energy consumption；A kind of electric wheel drive vehicle composite energy-saving servo steering system of the present invention can be by preceding
It takes turns left and right driving torque difference and generates power steering, power-assisted while reduces turning resistance, while front-wheel being made to be operated in motor height
Efficient point effectively reduces full-vehicle steering system and drive system energy consumption to compare more simple electric power steering technology；
In addition more simple differential power-assisted steering technology is compared, tire wear can also be reduced as far as possible, improve the quick of steering
Response improves driver road feel；
2, reliability is high；Include in a kind of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
Electric boosting steering system and differential servo steering system can be worked normally individually, when one system of any of which is lost
When effect, another force aid system can normally realize power-assisted, ensure that the reliability of vehicle；
3, safety is good；A kind of electric wheel drive vehicle composite energy-saving servo steering system of the present invention is in phase plane
Stable region to use differential power-assisted steering and electric power steering to work together energy saving to realize.It is in phase plane in vehicle-state
When unstable region, differential power-assisted steering at this time is closed, and the attachment of tire is all left to the stabilitrak of vehicle for, simultaneously
It avoids the positive additional yaw moment that differential power-assisted steering power-assisted generates and causes vehicle unstability.
Description of the drawings
Fig. 1 is a kind of structure diagram of electric wheel drive vehicle composite energy-saving servo steering system of the present invention.
Fig. 2 is a kind of master of the control method of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
Flow chart.
Fig. 3 is a kind of section of the control method of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
It can steering pattern sub-process figure.
Fig. 4 is a kind of reason of the control method of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
Think steering-wheel torque figure.
Fig. 5 is a kind of peace of the control method of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
Full steering pattern sub-process figure.
Fig. 6 is a kind of mistake of the control method of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
Effect protection steering pattern sub-process figure.
Specific implementation mode
Present invention will be described in further detail below with reference to the accompanying drawings, to enable those skilled in the art with reference to specification text
Word can be implemented according to this.
It should be appreciated that such as " having ", "comprising" and " comprising " term used herein do not allot one or more
The presence or addition of a other elements or combinations thereof.
As shown in Figure 1, a kind of electric wheel drive vehicle composite energy-saving servo steering device disclosed by the invention, by differential
The co-operation of the combination of power-assisted steering and electric boosting steering system, two systems can be by reducing turning resistance and optimization
The purpose for reducing whole system energy consumption is realized in motor operating point, while reducing the steering inertia of electric boosting steering system, carries
High dynamic response quality, while differential power-assisted steering can be improved with electric power steering respectively as the redundancy backup of other side
The reliability of vehicle；Turn apparatus body includes steering wheel 100, steering shaft 150, steering-wheel torque sensor 200, steering wheel
Rotary angle transmitter 250, assist motor 400, turbine and worm decelerator 300, rack and pinion steering gear 630, left steering drag link
610, right turn drag link 620, the near front wheel 600, left wheel hub motor 500, off-front wheel 650, right wheel hub motor 550, primal coordination control
Molding block 710, differential power-assisted steering control module 900, slippage rate control module 950 and electric power steering control module
800。
100 center of steering wheel is connected to steering shaft 150, be equipped in steering shaft 150 steering wheel angle sensor 200 and
Steering-wheel torque sensor 250, while the output end of turbine and worm decelerator 300, assist motor are connected in steering shaft 150
400 output ends are connected to the input terminal of turbine and worm decelerator 300.150 lower end of steering shaft is connected to rack and pinion steering gear
The tooth sector of 630 tooth sector, rack and pinion steering gear 630 is engaged with the rack of rack and pinion steering gear 630, gear teeth
The rack left and right ends of steering gear 630 respectively connected left steering drag link 610 and right turn drag link 620, and left steering is horizontal
The other end of pull rod 610 is connected to the knuckle of the near front wheel 600 by ball stud, and the other end of right turn drag link 620 passes through
Ball stud is connected to the knuckle of off-front wheel 650.Left wheel hub motor 500 is installed on the near front wheel 600, is installed on off-front wheel 650
There is right wheel hub motor 550.
Primal coordination control module 710, differential power-assisted steering control module 900, electric power steering control module 800 and
Slippage rate control module 950 forms the control unit (ECU) 700 of composite energy-saving servo steering system herein, control unit 700
It is connected with vehicle CAN bus, the speed v in CAN bus, side slip angle β, coefficient of road adhesion μ, total demand can be read and drive
Dynamic torque Tg.The steering-wheel torque T that steering wheel angle sensor 200 and steering-wheel torque sensor 250 measure can be read simultaneouslysw
And corner δsw.The 800 exportable control instruction of electric power steering control module in control unit 700 is to assist motor simultaneously
400,900 exportable control instruction of differential power-assisted steering control module in control unit 700 to slippage rate control module 950,
950 exportable motor control instruction of slippage rate control module is to the near front wheel wheel hub motor 500 and off-front wheel wheel hub motor 550.
In another embodiment, the primal coordination control module 710 in control unit (ECU) 700, electric power steering control
Molding block 800, differential power-assisted steering control module 900 and slippage rate control module 950 can individually be set as entity
Controller can be also integrated in the controller of an entity, or even can be integrated in vehicle drive control device.
As shown in Fig. 2, the present invention also provides a kind of controlling parties of electric wheel drive vehicle composite energy-saving servo steering system
Method realizes that the coordination to differential power-assisted steering and electric power steering controls, when effectively reducing steering by this control method
The total energy consumption of automobile, the energy-efficient purpose of solid line, while dynamic response quality when can improve power steering, and realize and work as one of them
Fail safe when thrashing, improves the safety of vehicle, and this method includes the following steps：
Step 1：System self-test；Primal coordination control module 710 reads the self-test signal of assist motor 400, if assist motor
400 failures, carry out step 5, if it is not, carrying out step 2；
Step 2：The yaw velocity ω of vehicle is obtained by yaw-rate sensorrSignal, by vehicle speed sensor or
Speed observer obtains vehicle speed signal v, and side slip angle β and side slip angle speed are obtained by side slip angle observer
DegreeSignal, by coefficient of road adhesion observer, observation obtains coefficient of road adhesion μ in real time；
Step 3：It is tabled look-up to obtain inhibited stably parameter value B according to coefficient of road adhesion μ1、B2；
Inhibited stably parameter value B1、B2It derives fromPhase plane stable region divides, and boundary is drawn using Double-Line Method
Point, that is, use two parallel straight lines to divide inhibited stably.I.e. describedPhase plane stable region can be by following public
Formula indicates：
Wherein, B1And B2For inhibited stably parameter, inhibited stably parameter is mainly related with coefficient of road adhesion, gives
Different coefficient of road adhesion obtains the boundary system under each attachment coefficient by the method that Computer Simulation or real vehicle are demarcated
Several values；In actual use, by B1、B2Tables of data is made to be previously stored into ECU, table look-at when use；Such as 1 institute of table
It is shown as B1、B2Parameter list.
Table 1B1、B2Parameter list
| Coefficient of road adhesion | B1 | B2 |
| 0.8≤μ≤1 | 0.283 | 0.175 |
| 0.6≤μ ＜ 0.8 | 0.343 | 0.167 |
| 0.4≤μ ＜ 0.6 | 0.378 | 0.152 |
| 0.3≤μ ＜ 0.4 | 0.454 | 0.150 |
| 0.2≤μ ＜ 0.3 | 0.624 | 0.138 |
| μ ＜ 0.2 | 0.938 | 0.03 |
Step 4:It calculatesValue, and judgeIt is whether true：If so, system into
Enter energy saving steering pattern, and jumps into step 6；If it is not, system enters safe steering pattern, and jump into step 6.
Step 5：System enters fail safe steering pattern.
Step 6：Steering pattern decision is completed.
If Fig. 3 is shown, in another embodiment, energy saving steering pattern includes the following steps：
Step 1：Read steering-wheel torque Tsw, speed v, steering wheel angle δswAnd total driving demand torque Tg；
Step 2：According to steering wheel angle δsw, speed v table look-up to obtain differential power-assisted steering work weight coefficient value k's in real time
Initial value kc；
In another embodiment, initial value kcOptimize to obtain by off-line simulation, it is whole using Simulink and Carsim etc.
Simulation calculation vehicle travels respectively in vehicle dynamics simulation software is determining speed, is determining steering wheel angle operating mode, turns to differential power-assisted
To work weight coefficient kcCarry out global optimizing；In the present embodiment, kcSearch Range be 0≤kc≤ 1, the mesh of offline optimization
Scalar functions are as follows：
In formula, T1For the motor output torque of the near front wheel；n1For the output rotating speed of the near front wheel；T2It is defeated for the motor of off-front wheel
Go out torque；n2For the output rotating speed of off-front wheel；a1、a2、a3Respectively weight coefficient；TtFor the output torque of assist motor；ntFor
The output rotating speed of assist motor；a1、a2、a3Respectively weight coefficient；λ1, λ2, λtRespectively left front turbin generator, off-front wheel motor with
And the efficiency of assist motor.
Target function value J is smaller, then the purpose for illustrating the initial value that energy-saving effect is better, and offline optimization obtains is to give down
The online optimizing of one step provides optimizing initial value, can significantly improve the speed of online optimizing in this way, has significant engineering significance,
Data are made in the differential power-assisted steering work weight coefficient k of the offline optimization of each speed and the operating mode for determining steering wheel angle
Table is stored in ECU, and when use directly invokes；As shown in table 2, when actual steering disk corner and speed occurrence do not exist
In table, using the method value of interpolation.
Table 2kcValue table
Step 3：Initial value k based on the differential power-assisted steering work weight coefficient value k to table look-upc, sought online
It is excellent, kcFor optimizing starting point, real-time online optimizing obtains the work weight coefficient of differential power-assisted steering；
The purpose of online optimizing is to make steering power most by what optimizing algorithm was calculated online current instantaneous moment
The differential power-assisted steering work weight coefficient value of hour, by differential power-assisted steering work weight coefficient value k obtained in the previous stepcIt does
For the starting point of optimization algorithm optimizing, it is greatly improved the speed of optimizing, meets the requirement of realtime control.
The object function of online optimizing is as follows：
In formula, TgFor total driving moment that main coordinating control module goes out according to speed and target vehicle speed mathematic interpolation, TzFor difference
The differential torque of front-wheel needed for power-assisted that dynamic power-assisted steering control module institute decision goes out, b1, b2, btRespectively corresponding optimization power
Weight coefficient.Target function value is smaller, illustrates that effect is better.The constraint equation of optimized variable k is as follows：c1kc≤k≤c2kc；In formula,
c1And c2Respectively optimize border coefficient, optimize border coefficient specific value need to according to the wheel hub of assist motor and front-wheel or
The power and torque characteristics of wheel motor determine, need to carry out train experiment and specifically be demarcated；In the present embodiment, c1Generally may be used
Value is 0.8, c2Generally can value be 1.2.
In another embodiment, optimization algorithm of the sequence least square method as on-line optimization is selected.
It is worth noting that the torque optimizing distribution method that the present invention chooses is Sequential Quadratic Programming method, but institute of the present invention
The torque optimizing distribution method method without being limited thereto stated, can also select other optimization methods on demand, this is not constituted to this
Invent the limitation of the claims.
Step 4：The differential torque T of the differential power-assisted steering control module output required front-wheel of power-assistedz；Electric power steering
Control module exports the control voltage signal needed for assist motor 400；
In another embodiment, differential power-assisted steering control module uses steering-wheel torque Direct control strategy；The control
System strategy measures actual steering-wheel torque T specifically by steering-wheel torque sensor 200sw, meanwhile, it obtains in CAN bus
Speed v and steering wheel angle δswSignal, the interior ideal steering-wheel torque MAP chart stored of Read Controller obtain reason at this time
Think steering-wheel torque Tswd, according to actual steering-wheel torque TswWith ideal steering-wheel torque TswdMathematic interpolation obtain left and right vehicle
Torque differences are taken turns so that the ideal steering-wheel torque of actual steering disk torque tracking, achievees the purpose that reduce turning to hand-power.
As shown in figure 4, ideal steering-wheel torque MAP passes through according to numerous companies before and research institution obtained by many experiments
Conclusion combination speed and steering wheel angle determine drivers preference hand-wheel torque, which manages
Think steering-wheel torque Tswd, ideal steering-wheel torque MAP data are stored into ECU in advance, table look-at when use.
In another embodiment, differential booster steering controller is chosen for PID controller, and controller input turns to be practical
To disk torque TswWith ideal steering-wheel torque TswdDifference, export as the differential torque T of front-wheel needed for power-assistedz；What is exported is differential
Torque TzIt is calculated by following formula：
In formula, e (t)=Tsw-Tswd, kp、ki、kdFor PID controller control parameter.
In another embodiment, a kind of electric wheel drive vehicle composite energy-saving servo steering system of the present invention
The differential booster steering controller of control method is not limited only to such PID controller, can also select design other kinds of on demand
Controller, this does not constitute the limitation of the claims to the present invention.
In another embodiment, electric booster steering controller equally uses steering wheel Strategy of Direct Torque Control；It should
Control strategy measures actual steering-wheel torque T specifically by steering-wheel torque sensorsw, meanwhile, it obtains in CAN bus
Speed v and steering wheel angle δswSignal reads ideal steering-wheel torque MAP chart and obtains ideal steering-wheel torque T at this timeswd,
400 voltage signal of assist motor is exported so that actual steering disk torque real-time tracking ideal steering-wheel torque by controller；
In the present embodiment, the ideal steering-wheel torque of ideal steering-wheel torque MAP chart and the use of differential booster steering controller herein
MAP chart is consistent.
In another embodiment, electric booster steering controller equally uses fuzzy controller；Fuzzy is by PID
Controller and fuzzy controller composition, fuzzy controller correct three parameter K of PID controller in real timep、Ki、Kd；Fuzzy control
The input of device is actual steering disk torque TswWith ideal steering-wheel torque TswdDifference e and difference change rate de/dt, export and be
Kp、Ki、KdCorrection value, and correction value is input to PID controller；The domain of difference e is { -5,5 }, and fuzzy set is { negative big
(NB), in bearing (NM), bear small (NS), zero (ZO) is just small (PS), hits exactly (PM), honest (PB), the opinion of difference change rate de/dt
Domain is { -10,10 }, and fuzzy set is that { negative big (NB) in bearing (NM), is born small (NS), and zero (ZO) is just small (PS), hits exactly (PM), just
(PB) greatly }.The control parameter K of outputp、Ki、KdDomain all be { 0,3 }, fuzzy set all be zero (ZO), it is just small (PS), center
(PM), honest (PB) }；Fuzzy control rule is shown in Table 3.
3 fuzzy controller fuzzy control rule table of table
The input of fuzzy controller is actual steering disk torque TswWith ideal steering-wheel torque TswdDifference, export and be
The control voltage of the control voltage signal of assist motor 400, output is calculated by following formula：
In formula, e (t)=Tsw-Tswd, Kp、Ki、KdValue exported in real time by fuzzy controller.
Step 5：According to the work weight coefficient k for the differential power-assisted steering that online optimizing obtains, that is, determines and export and is final
Export the differential torque Δ T of front-wheel power-assisted demandz, by total driving moment Tg, sideway needed for the output of differential booster steering controller
Li square Fen Pei two front-wheels of Give.
The differential torque Δ T of front-wheel of reality output to the power-assisted of torque distribution controllerzAbove-mentioned obtained difference need to be combined
Dynamic power-assisted steering work weight coefficient k, i.e. Δ TzIt is calculated by following formula：
ΔTz=kTz；
By total driving moment Tg, yaw moment Fen Pei two front-wheels of Give needed for the output of differential booster steering controller；
Shown in following formula：
In formula, Ti(i=1,2) it is respectively the near front wheel, off-front wheel output torque.
Step 6：The demand torque of distribute 2 wheels is carried out by each wheel slip rate control module 950 respectively
It corrects, the wheel demand torque T after each wheel is correctedsi(i=1,2) control instruction is sent to the wheel hub in each wheel
The controller of motor.
In another embodiment, specific modification method is as follows：Vehicle-related condition parameter is obtained based on measuring or estimating,
The slippage rate of each wheel is calculated in real time, while the best slippage rate of the wheel that when real-time estimation is each inscribes, the two make the difference
Pid control algorithm is inputted, when the practical slippage rate of wheel is more than optimum wheel slippage rate under the moment, slippage rate control module
950 start to work, and pid control algorithm calculates output slippage rate control and corrects torque Txi(i=1,2), correct torque directly with just
Beginning wheel demand torque TiIt is superimposed, that is, the wheel demand torque T after correctingsi(i=1,2) calculation formula is as follows：Tsi=Ti+
Txi；In the present embodiment, the best slippage rate control of slippage rate control method selection of the present invention, but it is of the present invention
Control method for coordinating is not limited only to apply such slippage rate control method, can also select other slippage rate control methods on demand,
This does not constitute the limitation to claims of the present invention.
Step 7：Assist motor 400 exports the diverted drive system mechanism of assist torque and acts on to steering wheel 100.
As shown in figure 5, in another embodiment, safe steering pattern includes the following steps：
Step 1：Read steering-wheel torque Tsw, speed v, steering wheel angle δswSignal；
Step 2：With according to steering wheel angle δsw, speed v tables look-up the ideal steering-wheel torque T of readingswd；
Step 3：By steering-wheel torque TswWith ideal steering-wheel torque TswdDifference input electric power steering control mould
Block；
Step 4：Electric power steering control module calculates the control electricity of assist motor 400 using Fuzzy PID
Signal is pressed, and voltage signal is delivered to assist motor；
Step 5：Assist motor 400 exports assist torque；
As shown in fig. 6, in another embodiment, fail safe steering pattern includes the following steps：
Step 1：Read steering-wheel torque Tsw, speed v, steering wheel angle δswAnd total driving demand torque TgSignal；
Step 2：With according to steering wheel angle δsw, speed v tables look-up the ideal steering-wheel torque T of readingswd；
Step 3：By steering-wheel torque TswWith ideal steering-wheel torque TswdDifference input differential power-assisted steering and control mould
Block；
Differential power-assisted steering control module described in this step uses pid control algorithm, specific with steering energy saver mode institute
The differential power-assisted steering control module pid control algorithm stated, is not repeating here.
Step 4：Differential power-assisted steering control module calculates the differential moment values T of the front-wheel of demandz, and pass through following formula
Calculate the moment values of left and right front-wheel demand；
Step 5：The demand moment values of calculated the near front wheel and off-front wheel are inputted to the slippage rate control of each wheel respectively
Module 950 is modified；
Step 6：The demand moment values of revised the near front wheel 600 and off-front wheel 650 are exported to the wheel hub electricity of the near front wheel
The electric machine controller of the wheel hub motor 550 of machine 500 and off-front wheel.
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 (10)
1. a kind of electric wheel drive vehicle composite energy-saving servo steering device, which is characterized in that including：
Steering wheel；
Steering shaft connects the steering wheel centre, and in installing angle sensor and torque sensor in the steering shaft；
Deceleration mechanism, output end connect the steering shaft；
Assist motor connects the input terminal of the deceleration mechanism；
Steering gear connects the steering shaft lower end, and connects wheel by drag link respectively at the steering gear both ends；
Electronic control unit, rotary angle transmitter, the torque sensor and vehicle CAN bus described in Electricity Federation；
Wherein, the electronic control unit includes primal coordination control device, motor-driven power steering control device, differential power-assisted steering
Control device and slippage rate control device；
Assist motor described in electric power steering control Electricity Federation；
Wheel hub motor in wheel described in slippage rate control device Electricity Federation.
2. electric wheel drive vehicle composite energy-saving servo steering device as described in claim 1, which is characterized in that the deceleration
Mechanism is set as worm gear structure.
3. electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 1 or 2, which is characterized in that described
Steering gear is rack pinion steering gear；
Wherein, the tooth sector of the rack pinion steering gear connects the lower end of the steering shaft；And
The rack of the rack pinion steering gear and tooth sector engaged transmission, and the rack connects the horizontal drawing
Bar.
4. electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 3, which is characterized in that the horizontal drawing
Bar is connected by ball stud with the knuckle of the wheel.
5. a kind of control method of electric wheel drive vehicle composite energy-saving servo steering device, described in claim 1-4
Transfer, which is characterized in that include the following steps：
Step 1: judging assist motor, if assist motor fails, electronic control unit enters fail safe control
Pattern；If assist motor normal operation, data acquisition, including yaw velocity ω are carried outr, speed v, side slip angle β,
Side slip angle speedWith coefficient of road adhesion μ；
Step 2: determining inhibited stably parameter value B according to the coefficient of road adhesion μ1、B2, and according to the stable region side
Boundary parameter value B1、B2Phase plane Calculation of Stability Region is carried out, ifWhen, then electronic control unit enters section
Energy steering pattern, ifWhen, then electronic control unit enters safe steering pattern；
Wherein, the energy saving steering pattern includes：
Monitor steering-wheel torque Tsw, speed v, steering wheel angle δswAnd total driving demand torque Tg；According to the steering wheel
Corner δswThe different values with speed v's obtain differential power-assisted steering by the first optimization object function and work weight coefficient value k's
Different initial values, and carry out the initial value k after data preparation is optimizedc；Wherein, optimization process makes the first optimization aim letter
Number value is minimum；
First optimization object function is
In formula, T1For the motor output torque of the near front wheel；n1For the output rotating speed of the near front wheel；T2For the motor power output of off-front wheel
Square；n2For the output rotating speed of off-front wheel；a1、a2、a3Respectively weight coefficient；TtFor the output torque of assist motor；ntFor power-assisted
The output rotating speed of motor；a1、a2、a3Respectively weight coefficient；λ1, λ2, λtIt respectively left front turbin generator, off-front wheel motor and helps
The efficiency of force motor；
According to the initial value kcThe optimizing of work weight coefficient value k is carried out by the second optimization object function；Wherein, wherein excellent
Change process keeps the second optimization object function value minimum；
Second optimization object function is
The constraint equation of work weight coefficient value k is c1kc≤k≤c2kc；
In formula, TgFor total driving moment that main coordinating control module goes out according to speed and target vehicle speed mathematic interpolation, TzIt is helped to be differential
The differential torque of front-wheel needed for power-assisted that power course changing control module institute decision goes out, b1, b2, btRespectively optimize weight system accordingly
Number, c1And c2Respectively optimize border coefficient；
Determine the differential torque T of front-wheelzWith the control voltage signal needed for assist motor, determined according to the work weight coefficient value k
The differential torque Δ T of final output front-wheel power-assisted demandz, by total driving moment Tg, needed for the output of differential booster steering controller
Yaw moment distributes to two front-wheels, and is modified by skidding rate of rotation control device, and assist motor exports assist torque warp
Steering transmission mechanism is acted on to steering wheel.
6. the control method of electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 5, feature exist
In the safe steering pattern includes：
Monitor steering-wheel torque Tsw, speed v, steering wheel angle δsw, according to the steering wheel angle δswIdeal is obtained with speed v
Steering-wheel torque Tswd；
By the steering-wheel torque TswWith the ideal steering-wheel torque TswdDifference input motor-driven power steering control device,
The control voltage signal of assist motor is calculated by fuzzy, and voltage signal is delivered to assist motor, exports power-assisted power
Square.
7. the control method of electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 5, feature exist
In the fail safe steering pattern includes：
Monitor steering-wheel torque Tsw, speed v, steering wheel angle δswWith total driving demand torque TgWith according to the steering wheel angle
δswIdeal steering-wheel torque T is obtained with speed vswd；
By the steering-wheel torque TswWith the ideal steering-wheel torque TswdDifference input differential power-assisted steering control device,
The differential moment values T of the front-wheel of demand is calculated by PIDz, and calculate the moment values of left and right front-wheel demand；
The slippage rate control device that the demand moment values of calculated the near front wheel and off-front wheel are inputted to each wheel respectively is repaiied
Just, revised front-wheel demand moment values are exported to wheel hub motor and is controlled.
8. the control method of electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 5, feature exist
In,
Determine the differential torque T of front-wheelzIt is exported by differential power-assisted steering control device, the differential power-assisted steering control dress
It sets and uses PID controller；And
Determine that the control voltage signal needed for assist motor is exported by motor-driven power steering control device, it is described electronic to help
Power steering control device uses fuzzy controller.
9. the control method of electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 8, feature exist
In the differential torque Δ T of front-wheelzIt is calculated by the following formula：
In formula, Ti(i=1,2) it is respectively the near front wheel, off-front wheel output torque.
10. the control method of electric wheel drive vehicle composite energy-saving servo steering device as claimed in claim 9, feature exist
In being modified process to the skidding rate of rotation control device includes：
The slippage rate of each wheel is calculated in real time, while the best slippage rate of the wheel that when real-time estimation is each inscribes, work as vehicle
When the practical slippage rate of wheel is more than optimum wheel slippage rate under the moment, slippage rate control device is started to work, and is calculated by PID control
Method calculates output slippage rate control and corrects torque Txi(i=1,2), the wheel demand torque T after correctingsi(i=1,2) it calculates
Formula is Tsi=Ti+Txi。
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