CN104443022B - A kind of four motorized wheels electric car stability control method and system - Google Patents
A kind of four motorized wheels electric car stability control method and system Download PDFInfo
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- CN104443022B CN104443022B CN201410632581.0A CN201410632581A CN104443022B CN 104443022 B CN104443022 B CN 104443022B CN 201410632581 A CN201410632581 A CN 201410632581A CN 104443022 B CN104443022 B CN 104443022B
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
- B60W30/02—Control of vehicle driving stability
- B60W30/045—Improving turning performance
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
- B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
- B60W40/105—Speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2300/00—Indexing codes relating to the type of vehicle
- B60W2300/18—Four-wheel drive vehicles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2520/00—Input parameters relating to overall vehicle dynamics
- B60W2520/10—Longitudinal speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2540/00—Input parameters relating to occupants
- B60W2540/18—Steering angle
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- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
- Electric Propulsion And Braking For Vehicles (AREA)
Abstract
The invention discloses a kind of four motorized wheels electric car stability control method and systems, it solves electric car ARS in the prior art and two security system of DYC works at the same time, the technical issues of appearance couples and reduces vehicle performance, the described method includes: obtaining steering wheel angle and speed when Vehicular turn；Based on speed and speed transmission ratio mathematical model, the variable ratio between steering wheel and rear-wheel corner is obtained；Front wheel angle is obtained based on steering wheel angle；Vehicle perfect condition is obtained based on variable ratio vehicle ideal model, speed and front wheel angle；Based on the non-linear eight degrees of freedom model of electric car, speed and front wheel angle, vehicle virtual condition is obtained；Obtain vehicle-state error of the vehicle virtual condition relative to vehicle perfect condition；Make for turner in nonlinear area or linear region, respectively by ARS+DYC or ARS, vehicle-state error is eliminated or reduced in control, so that vehicle stabilization is run.
Description
Technical field
The present invention relates to electric vehicle stability control technical fields more particularly to a kind of four motorized wheels electric vehicle to stablize
Property control method and system.
Background technique
With the development of automotive engineering, electric car due to using high efficiency rechargeable battery or fuel cell for power source,
The pernicious gas of not exhaust emission atmosphere itself, even if being scaled the discharge in power plant by institute's power consumption, outside sulphur removal and particle,
Its pollutant also substantially reduces, and greatly improves economic results in society.In addition, it is related studies have shown that same crude oil is by thick refining,
It sending to power plants generating electricity, is filled with battery, then automobile is driven by battery, energy utilization efficiency ratio becomes gasoline by refining, then
It is high through gasoline engine driving automobile, therefore be conducive to discharge capacity that is energy saving and reducing carbon dioxide, exactly these advantages, make electronic
The research and application of automobile become one " hot spot " of auto industry.Electric car has occupied partial automobile city on the market at present
Market share, and liked by the majority of consumers.
In order to improve the control stability of electric car, some safety control technologies have been applied to automobile, such as directly
Yaw moment control (DYC, Direct Yaw-moment Control), active front wheel steering (AFS, Active Front-
Wheel Steering), active rear steer (ARS, Active Rear-wheel Steering), pull-in control system
(TCS, Traction Control System) and electronic stability program (ESP, ElectronicStability Program)
Deng.
Electric car usually steering, high speed or pass through bad road when will appear unstable factor.People are normal
The steering system of a vehicle can be evaluated with accurate, light, and steering system is directly concerning the driving safety of vehicle and manipulation
Performance.Steering characteristic can be generally divided into three kinds of understeer, neutral steer and oversteering situations.Rear-axle steering exist with it is preceding
In the same direction and reversed two kinds of situations are taken turns, and both of these case can also show two kinds of entirely different steering characteristics, in simple terms
It is exactly increase understeer in the same direction, reversely increases oversteering.Vehicle when running at a low speed, can pass through the anti-of rear-wheel and front-wheel
Come suitably to increase ovdersteering to rotation.It is auxiliary in no any electronics when the case where vehicle run at high speed encounters urgent modified line
With the help of auxiliary system, it is easy to the tendency of ovdersteering occur, by active rear steer (ARS) one very little of generation but very
The important trend that ovdersteering can be then made up with the steering of the front-wheel same direction, can allow automobile to have better balance in this way
Property.In addition, in order to desalinate influence of the operative skill of driver to vehicle movement safety, in the various driving status of vehicle
Under be adjusted by the stress to each wheel, automobile direct yaw moment (DYC) control generate yaw moment overcome excessively
Steering or understeer, so that initiatively carrying out dynamics Controlling to vehicle improves automobile in the limit item such as high speed and bad road
Control stability when part downward driving；That is, ARS and DYC be electric car compared with frequently with stability control means.
But these safety control systems (such as DYC, ARS) are all independent designs to solve or improve the specificity of automobile
Energy.When each system works at the same time on vehicle, the coupled problem occurred between system can reduce the performance of its vehicle.Namely
It says, in the prior art, when electric car direct yaw moment control system and active rear steer system work at the same time, two
It will appear coupling between security system and reduce vehicle performance.
Summary of the invention
The present invention is for existing in the prior art when electric car direct yaw moment control system and Active Rear turn
When working at the same time to system, the problem of will appear coupling between two security systems and reduce vehicle performance, a kind of four-wheel is provided
Independent driving electric car stability control method and system, to improve the maneuverability of vehicle when running at a low speed and run at high speed
When stability.
On the one hand, described the embodiment of the invention provides a kind of four motorized wheels electric car stability control method
Method comprising steps of
S1, when four-wheel independent steering electric car is in running order and needs to turn to, obtain the electric car
Steering wheel angle and speed；Wherein, the speed is variable velocity；
S2, it is based on the speed and speed transmission ratio mathematical model, obtains the side of the electric car under different speeds
Variable ratio between disk and rear-wheel corner；
S3, it is based on the steering wheel angle, obtains the front wheel angle of the electric car；
S4, it is based on variable ratio vehicle ideal model, the speed and the front wheel angle, obtains the electric car
Vehicle perfect condition；Meanwhile it being based on the non-linear eight degrees of freedom model of electric car, the speed and the front wheel angle, it obtains
The vehicle virtual condition of the electric car；And then obtain vehicle of the vehicle virtual condition relative to the vehicle perfect condition
State error；
S5, after obtaining the vehicle-state error, when electric car work is in nonlinear area, pass through institute
The active rear steer controller and direct yaw moment control device of electric car are stated, the vehicle-state is eliminated or reduced in control
Error, so that the electric car stable operation；When the electric car work at linear region, pass through the Active Rear
Steering controller, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
Optionally, the active rear steer controller is by linear sliding mode control module structure；The direct sideway
Torque controller is by nonlinear sliding mode control module structure.
Optionally, the variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model,
The step S4 the following steps are included:
S41, the attachment coefficient for obtaining electric car institute track；
S42, the variable ratio two degrees of freedom vehicle dynamic model, the attachment coefficient, the speed and institute are based on
Front wheel angle is stated, the expectation yaw velocity of the electric car is obtained；Meanwhile being based on the non-linear eight degrees of freedom mould of electric car
Type, the speed and the front wheel angle obtain the practical yaw velocity of the electric car；And then it obtains described practical horizontal
Yaw-rate error of the pivot angle speed relative to the expectation yaw velocity.
Optionally, the step S5, comprising steps of
S51, it is based on the attachment coefficient, determines the electric car work in linear region or nonlinear area；
S52, when the vehicle operation is at linear region, by the active rear steer controller, control the electricity
The rear wheel of electrical automobile obtains the first rear-wheel corner of the electric car；And after being based on the front wheel angle, described first
Corner and the non-linear eight degrees of freedom model of the electric car are taken turns, control is eliminated or reduces the yaw-rate error, with
Make the electric car stable operation；
When the vehicle operation is in nonlinear area, by the active rear steer controller, control is described electronic
The rear wheel of automobile obtains the second rear-wheel corner of the electric car；Meanwhile passing through the direct yaw moment control
Device obtains the wheel tyre power of the electric car, and generates compensation yaw moment based on the wheel tyre power；And based on institute
State front wheel angle, the second rear-wheel corner, the compensation yaw moment and the non-linear eight degrees of freedom mould of the electric car
Type, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
Optionally, the first rear-wheel corner is the multinomial about the first saturation function；The second rear-wheel corner is
Multinomial about the second saturation function；The compensation yaw moment is the multinomial about sign function；Wherein, described first
Saturation function and second saturation function are specially the saturation function about the first sliding-mode surface integral operator, the sign function
Saturation function specially about the second sliding-mode surface integral operator.
On the other hand, the embodiment of the invention also provides a kind of four motorized wheels electric car stabilitrak,
The system comprises steps:
Steering wheel angle and speed acquiring unit, for when four-wheel independent steering electric car is in running order and needs
When steering, the steering wheel angle and speed of the electric car are obtained；Wherein, the speed is variable velocity；
Variable ratio acquiring unit is obtained for being based on the speed and speed transmission ratio mathematical model in different speeds
Under the electric car steering wheel and rear-wheel corner between variable ratio；
Front wheel angle acquiring unit obtains the front wheel angle of the electric car for being based on the steering wheel angle；
Vehicle-state acquiring unit, for being based on variable ratio vehicle ideal model, the speed and the front wheel angle,
Obtain the vehicle perfect condition of the electric car；Meanwhile based on the non-linear eight degrees of freedom model of electric car, the speed and
The front wheel angle obtains the vehicle virtual condition of the electric car；And then the vehicle virtual condition is obtained relative to institute
State the vehicle-state error of vehicle perfect condition；
Stability control unit is used for after obtaining the vehicle-state error, when the electric car works non-
When linear region, by the active rear steer controller and direct yaw moment control device of the electric car, control is eliminated
Or reduce the vehicle-state error, so that the electric car stable operation；When the electric car works in linear region
When, by the active rear steer controller, control is eliminated or reduces the vehicle-state error, so that the electric car
Stable operation.
Optionally, the active rear steer controller is by linear sliding mode control module structure；The direct sideway
Torque controller is by nonlinear sliding mode control module structure.
Optionally, the variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model,
The vehicle-state acquiring unit, comprising:
Coefficient of road adhesion obtains module, for obtaining the attachment coefficient of electric car institute track；
Vehicle-state obtains module, for being based on the variable ratio two degrees of freedom vehicle dynamic model, the attachment
Coefficient, the speed and the front wheel angle obtain the expectation yaw velocity of the electric car；Meanwhile being based on electronic vapour
The linear eight degrees of freedom model of Chefei, the speed and the front wheel angle, obtain the practical yaw velocity of the electric car；
And then obtain yaw-rate error of the practical yaw velocity relative to the expectation yaw velocity.
Optionally, the stability control unit, comprising:
Working region determining module determines the electric car work in linear region for being based on the attachment coefficient
Or nonlinear area；
Stability control module, for passing through the active rear steer control when the vehicle operation is at linear region
Device processed controls the rear wheel of the electric car, obtains the first rear-wheel corner of the electric car；And it is based on the front-wheel
The cross is eliminated or is reduced in corner, the first rear-wheel corner and the non-linear eight degrees of freedom model of the electric car, control
Pivot angle velocity error, so that the electric car stable operation；
When the vehicle operation is in nonlinear area, by the active rear steer controller, control is described electronic
The rear wheel of automobile obtains the second rear-wheel corner of the electric car；Meanwhile passing through the direct yaw moment control
Device obtains the wheel tyre power of the electric car, and generates compensation yaw moment based on the wheel tyre power；And based on institute
State front wheel angle, the second rear-wheel corner, the compensation yaw moment and the non-linear eight degrees of freedom mould of the electric car
Type, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
Optionally, the first rear-wheel corner is the multinomial about the first saturation function；The second rear-wheel corner is
Multinomial about the second saturation function；The compensation yaw moment is the multinomial about sign function；Wherein, described first
Saturation function and second saturation function are specially the saturation function about the first sliding-mode surface integral operator, the sign function
Saturation function specially about the second sliding-mode surface integral operator.
The one or more technical solutions provided in the embodiment of the present invention, have at least the following technical effects or advantages:
Due in embodiments of the present invention, when four-wheel independent steering electric vehicle is in running order and needs to turn to, leading to
Cross the steering wheel angle and speed for obtaining the electric vehicle；Based on the speed and speed transmission ratio mathematical model, obtain not
With the variable ratio between the steering wheel and rear-wheel corner of electric vehicle described under speed；It is based on the steering wheel angle again, obtains
The front wheel angle of the electric vehicle；Further, in conjunction with variable ratio vehicle ideal model, the speed and the front wheel angle,
Obtain the vehicle perfect condition of the electric vehicle；Meanwhile being based on the non-linear eight degrees of freedom model of electric car, the speed and institute
Front wheel angle is stated, the vehicle virtual condition of the electric car is obtained；And then the vehicle virtual condition is obtained relative to described
The vehicle-state error of vehicle perfect condition；Finally after obtaining the vehicle-state error, when the electric car works
In nonlinear area, pass through the active rear steer controller and direct yaw moment control device of the electric car, control
The vehicle-state error is eliminated or reduces, so that the electric car stable operation；When the electric car works linear
When region, by the active rear steer controller, control is eliminated or reduces the vehicle-state error, so that described electronic
Vehicle running stability；That is, being based on variable ratio vehicle ideal model and the non-linear eight degrees of freedom model of electric car, root
According to the real work situation of vehicle, such as work selects suitable security system to be stablized in linear region or nonlinear area
Property control only enable an active rear steer controller and carry out security control specifically, when vehicle operation is at linear region, when
Vehicle operation enables active rear steer controller and direct yaw moment control device carries out safety simultaneously in nonlinear area
Control, solves in the prior art when electric car direct yaw moment control system and active rear steer system work at the same time
When, the technical issues of will appear coupling between two security systems and reduce vehicle performance, when improving low vehicle speeds
Maneuverability and stability when running at high speed.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
The embodiment of invention for those of ordinary skill in the art without creative efforts, can also basis
The attached drawing of offer obtains other attached drawings.
Figure 1A-Fig. 1 D is four-wheel independent steering electric vehicle rotary provided in an embodiment of the present invention to schematic diagram；
Fig. 2 is the first four motorized wheels electric car stability control method process provided in an embodiment of the present invention
Figure；
Fig. 3 is second of four motorized wheels electric car stability control method process provided in an embodiment of the present invention
Figure；
Fig. 4 is that electric car relevant to speed provided in an embodiment of the present invention turns to variable ratio curve graph；
Fig. 5 is SAE standard coordinate system eight degrees of freedom auto model schematic diagram provided in an embodiment of the present invention；
Fig. 6 is the third four motorized wheels electric car stability control method process provided in an embodiment of the present invention
Figure；
Fig. 7 is the linear two degrees of freedom vehicle mould that active rear steer controller design provided in an embodiment of the present invention uses
Type；
Fig. 8 be speed v=30m/s provided in an embodiment of the present invention and attachment coefficient be μ=0.85 Matlab emulation it is defeated
Enter steering angle schematic diagram；
Fig. 9 be speed v=30m/s provided in an embodiment of the present invention and attachment coefficient be μ=0.45 Matlab emulation it is defeated
Enter steering angle schematic diagram；
Figure 10 A- Figure 10 D is that non-control system provided in an embodiment of the present invention and the emulation of ARS+DYC integrated control system are tied
Fruit comparison diagram；
Figure 11 A- Figure 11 D is non-control system provided in an embodiment of the present invention, ARS control system and ARS+DYC integrated
Control System Imitation comparative result figure；
Figure 12 A- Figure 12 C is DYC control system provided in an embodiment of the present invention and ARS+DYC integrated control system emulation knot
Fruit comparison diagram；
Figure 13 is the first four motorized wheels electric car stabilitrak structure provided in an embodiment of the present invention
Block diagram；
Figure 14 is second of four motorized wheels electric car stabilitrak structure provided in an embodiment of the present invention
Block diagram.
Specific embodiment
The embodiment of the present invention solves the prior art by providing a kind of four-wheel independent steering electric vehicle rotating direction control method
Present in when electric car direct yaw moment control system and active rear steer system work at the same time, two safety systems
The technical issues of will appear coupling between system and reducing vehicle performance, maneuverability and high speed when improving low vehicle speeds are gone
Stability when sailing.
The technical solution of the embodiment of the present invention is in order to solve the above technical problems, general thought is as follows:
The embodiment of the invention provides a kind of four motorized wheels electric car stability control method, the method includes
Step: when four-wheel independent steering electric car is in running order and needs to turn to, the steering wheel of the electric car is obtained
Corner and speed；Wherein, the speed is variable velocity；Based on the speed and speed transmission ratio mathematical model, obtain not
With the variable ratio between the steering wheel and rear-wheel corner of electric car described under speed；Based on the steering wheel angle, obtain
The front wheel angle of the electric car；Based on variable ratio vehicle ideal model, the speed and the front wheel angle, institute is obtained
State the vehicle perfect condition of electric car；Meanwhile based on the non-linear eight degrees of freedom model of electric car, the speed and it is described before
Corner is taken turns, the vehicle virtual condition of the electric car is obtained；And then the vehicle virtual condition is obtained relative to the vehicle
The vehicle-state error of perfect condition；After obtaining the vehicle-state error, pass through the Active Rear of the electric car
Steering controller and direct yaw moment control device, or by the active rear steer controller, institute is eliminated or reduces in control
Vehicle-state error is stated, so that the electric car stable operation.
As it can be seen that in embodiments of the present invention, freely based on variable ratio vehicle ideal model and electric car non-linear eight
Model is spent, according to the real work situation of vehicle, such as work selects suitable security system in linear region or nonlinear area
Stability control is carried out, specifically, only enabling active rear steer controller when vehicle operation is at linear region and carrying out safety
Control, when vehicle operation is in nonlinear area, enabling active rear steer controller and direct yaw moment control device are simultaneously
Security control is carried out, is solved in the prior art when electric car direct yaw moment control system and active rear steer system
When working at the same time, the technical issues of will appear coupling between two security systems and reduce vehicle performance, vehicle low speed is improved
Maneuverability when driving and stability when running at high speed.
In order to better understand the above technical scheme, in conjunction with appended figures and specific embodiments to upper
It states technical solution to be described in detail, it should be understood that the specific features in the embodiment of the present invention and embodiment are to the application
The detailed description of technical solution, rather than the restriction to technical scheme, in the absence of conflict, the present invention are implemented
Technical characteristic in example and embodiment can be combined with each other.
Embodiment one
The embodiment of the invention provides a kind of four motorized wheels electric car stability control methods；Wherein, four-wheel is only
There are four independent power drive motor and four independent steering driving motors, i.e., each wheels for vertical driving electric car setting
Driving motor there are two being respectively set, one is used as power drive, another is used as turning to driving, such wheel
Driving design, so that the angle of car rotation becomes larger, it is (including positive and reversed each 90 that each wheel can carry out 180 degree steering
Degree), it might even be possible to transverse shifting, as shown in Figure 1；Specifically, Figure 1A indicates that vehicle pivot stud, Figure 1B indicate vehicle cross running,
Fig. 1 C indicates vehicle homodromic deflection (if former driving direction is to the right, steering direction is still right), and Fig. 1 D indicates the incorgruous deflection of vehicle (such as original
Driving direction is that the right, steering direction is still left).Then, referring to FIG. 2, the rotating direction control method comprising steps of
S1, when four-wheel independent steering electric vehicle is in running order and needs to turn to, obtain the direction of the electric vehicle
Disk corner and speed；Wherein, the speed is variable velocity；
S2, it is based on the speed and speed transmission ratio mathematical model, obtains the direction of the electric vehicle under different speeds
Variable ratio between disk and rear-wheel corner；
S3, it is based on the steering wheel angle, obtains the front wheel angle of the electric vehicle；
S4, it is based on variable ratio vehicle ideal model, the speed and the front wheel angle, obtains the electric car
Vehicle perfect condition；Meanwhile it being based on the non-linear eight degrees of freedom model of electric car, the speed and the front wheel angle, it obtains
The vehicle virtual condition of the electric car；And then obtain vehicle of the vehicle virtual condition relative to the vehicle perfect condition
State error；
S5, after obtaining the vehicle-state error, when electric car work is in nonlinear area, pass through institute
The active rear steer controller and direct yaw moment control device of electric car are stated, the vehicle-state is eliminated or reduced in control
Error, so that the electric car stable operation；When the electric car work at linear region, pass through the Active Rear
Steering controller, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
Automotive control system belongs to switching dynamical system, it is by several continuous time subsystems or discrete time subsystem
And corresponding switching law is constituted.Due to the effect of switching law, so that switching system is different from general continuous time
System or discrete-time system, dynamic characteristic become extremely complex.One distinguishing feature of the stability of switching system is son
The stability of system is not equal to the stability of whole system.Even if each subsystem of switching system is Linear Time-Invariant System,
It is not generally linear system that it is whole, and belongs to nonlinear system.Sliding mode control theory (SMC, Sliding Mode
Control) be variable structure control theory main theory system, it has formd the independent theoretical of a whole set of integrated system,
It include: the reaching condition of the design method of sliding mode, the various integrated approach of controller, the stability analysis of system, system
Deng；Variable structure control theory is for solving the problems, such as a kind of Control of Nonlinear Systems method well；Sliding mode control strategy passes through
The switching of control amount moves system mode along sliding-mode surface, so that system has invariance when by external disturbance,
Therefore Sliding mode variable structure control may be used on handling various nonlinear systems；The basic principle of Sliding Mode Variable Structure System exists
In when system mode passes through the sliding hyperplane of state space, the structure of feedback control just changes, to make systematicness
Some expectation index can be reached；The effect of Sliding Mode Controller is exactly that the state of system is driven simultaneously within the limited time
It maintains on the submanifold；The advantages of sliding formwork control is the uncertainty that can overcome system, is had to interference and Unmarried pregnancy
There is very strong robustness, especially there is good control effect to the control of nonlinear system.
In the specific implementation process, in order to improve control effect of the electric car under limiting condition, the Active Rear
Steering controller is by linear sliding mode control module structure；The direct yaw moment control device controls mould by nonlinear sliding mode
Block structure.
In the prior art, mostly using linear two degrees of freedom vehicle dynamic model as the reference of vehicle stabilization control
Model to avoid the gain problems of too under vehicle high-speed, and has ignored the gain of vehicle under the low speed and crosses minor issue.However,
For having for the automobile of ideal steering characteristic, it is expected that yaw velocity should be reduced with the increase of speed, under the low speed
With biggish steering gain, high speed is lower to have lesser steering gain.In this regard, in the present embodiment, in order to make vehicle as far as possible
Reach ideal steering characteristic, the reference model using variable ratio vehicle ideal model as vehicle stabilization control, wherein
The variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, referring to FIG. 3, the step
Rapid S4 the following steps are included:
S41, the attachment coefficient for obtaining electric car institute track；
S42, the variable ratio two degrees of freedom vehicle dynamic model, the attachment coefficient, the speed and institute are based on
Front wheel angle is stated, the expectation yaw velocity of the electric car is obtained；Meanwhile being based on the non-linear eight degrees of freedom mould of electric car
Type, the speed and the front wheel angle obtain the practical yaw velocity of the electric car；And then it obtains described practical horizontal
Yaw-rate error of the pivot angle speed relative to the expectation yaw velocity.
In the specific implementation process, firstly, steering wheel angle detection device and the vehicle speed detector device difference for passing through vehicle
Detection obtains the steering wheel angle and speed of vehicle；Then, according to the mathematical relationship of BMW vehicle speed and transmission ratio, this reality is obtained
Transmission ratio (i.e. described variable ratio) of the vehicle between the steering wheel under different speeds and rear-wheel corner in example is applied, determining
After stating variable ratio, when input direction disk corner can be obtained by front wheel angle.Since the purpose of Vehicle Stability Control is
The stable state and transient response for improving automobile, improve the mobility of automobile and the ability of safety and anti-external disturbance, and automobile
Yaw velocity (i.e. yaw rate of the automobile around vertical axis) and side slip angle be measure vehicle steadily degree it is important
Parameter, if yaw rate reaches a threshold value, illustrates that automobile occurs to survey sliding or whipping etc. when one timing of side slip angle
Dangerous working condition.Below by using the yaw velocity of vehicle as measure vehicle-state major parameter, to step S41~S42 into
Row illustrates:
1) the expectation yaw velocity of four-wheel automobile is obtained based on coefficient of road adhesion
It, can not using the linear two degrees of freedom vehicle dynamic model of steering gear ratio is determined due in existing traditional technology
Meet Vehicle turning stability requirement；For this purpose, in the present embodiment, being asked using variable ratio two degrees of freedom vehicle dynamic model
Desired yaw velocity is taken, by variable ratio ivSubstitute stable drive ratio i.Thus, it is possible to obtain expectation yaw velocity:
In formula,θsw=i δf。
In formula (1), v is vehicle centroid speed, KvFor understeer coefficient, θswFor steering wheel angle, δfFor front wheel angle,
M is complete vehicle quality, lfAnd lrRespectively center of gravity is to axle distance, CfAnd CrThe respectively cornering stiffness of front and rear wheel, L be before,
Hind axle away from.
Currently, variable ratio can provide significant effect to steering vehicle turning, and the manipulation for significantly improving driver is steady
It is qualitative.In the present embodiment, as shown in figure 4, being electric vehicle rotary relevant to speed to variable ratio curve graph, the change taken is passed
It is dynamic to compare ivIt is related with speed v to move mathematic(al) function；In middle low speed, ivSmaller, steering is more direct, light, is substantially reduced driver
Steering task；In high speed, ivIt is larger, the more heavy of change is turned to, the steering task of driver is increased, direction is improved and stablizes
Property.
Since automobile yaw velocity is also limited by road surface attachment condition, limiting value and coefficient of road adhesion and vehicle
Speed is related, as shown in formula (2),
In formula (2), r is the practical yaw velocity of automobile, rmaxFor the practical yaw velocity maximum value of automobile, μ be tire and
Nominal coefficient of friction (the i.e. described attachment coefficient) between ground, g are acceleration of gravity, and v is vehicle degree.
Therefore, after considering the adhesive force in practical application between vehicle and ground, vehicle expectation yaw velocity is repaired
Just are as follows:
In formula (3), sgn (δf) it is sign function about front wheel angle.
In the actual process, there is biggish oscillation or overshoot in the transient response of yaw rate in order to prevent, needs
First-order filtering is carried out to the vehicle expectation yaw velocity in formula (3), obtains finally it is expected yaw velocity rd' are as follows:
In formula (4), s is Laplace operator, τrFor yaw velocity delay time, value range is (0.1~0.25)
s。
2) the practical yaw velocity of four-wheel automobile is obtained based on the non-linear eight degrees of freedom model of electric car
In the present embodiment, using international automobile Association of Engineers (SAE, Society of Automotive
Engineers) conventional coordinates (as shown in Figure 5) establishes 8 freedom degrees (DOF, Degree of Freedom) auto model, tool
Body includes vertical and horizontal movement, weaving, the rotational motion of roll motion and four wheels of vehicle body, totally 8 freedom
Degree, ignores the vertical and pitching movement of vehicle.By the available 8DOF vehicle equation of motion as follows of Fig. 5:
Longitudinal movement equation:
Transverse movement equation:
Weaving equation:
Roll motion equation:
The vehicle wheel rotation equation of motion:
In above-mentioned equation (5)~(10), m is complete vehicle quality, msFor spring carried mass, U is longitudinal velocity, and V is laterally fast
Degree, r is yaw velocity,For angle of heel, p is roll velocity, lfAnd lrRespectively distance of the vehicle's center of gravity to antero posterior axis, Tf
And TrRespectively wheel base, e are distance of the spring load-carrying heart to roll axis, IzAnd IxRespectively turn of the vehicle around z-axis and roll axis
Dynamic inertia, IxzFor the spring carried mass product of inertia, IwFor tyre rotation inertia, RwFor tire radius, ωiFor tyre rotation angular speed,
TdiAnd TbiThe driving moment and braking moment on tire are respectively acted on,WithRespectively roll stiffness and inclination resistance,
FxiAnd FyiRespectively along the tire force of X and Y-direction, wherein i=fl indicates that the near front wheel, i=fr indicate off-front wheel, i=rl table
Show that left rear wheel, i=rr indicate off hind wheel.
Tire force FxiAnd FyiIt can be obtained by coordinate transform:
Fxi=Fticosδi-FsisinδiWith i=fl, fr, rl, rr (11)
Fyi=Ftisinδi+FsicosδiWith i=fl, fr, rl, rr (12)
Wherein, FtiAnd FsiRespectively longitudinal tire force and lateral tire force, δiFor four-wheel corner.
In view of the load transfer due to caused by vertical and horizontal acceleration, the nominal vertical load of tire can be indicated such as
Under:
Wherein, l=a+b is wheelbase；A is distance of the front-wheel to mass center；B is distance of the rear-wheel to mass center；hcgFor spring charge material
Measure height of C.G.；KR=Kf/(Kf+Kr), KfAnd KrRespectively front and back roll stiffness；ayFor the transverse acceleration at mass center, indicate
ForR is yaw velocity, and v is speed, KvFor automobile understeer gradient, θswFor front wheel angle, i
To determine steering gear ratio.
Automobile is as follows with respect to the coordinate on ground:
In formula (17) and formula (18), ψ be vehicle centroid at yaw angle, be expressed as the practical yaw velocity of vehicle and when
Between product.
Under the premise of the speed of known electric car and front wheel angle, institute can be calculated based on formula (5)~(18)
State the practical yaw velocity of electric car；And then the practical yaw velocity is obtained relative to the expectation yaw velocity
Yaw-rate error.
Further, referring to FIG. 6, after successively executing the step S41 and step S42, step S5, the step are executed
S5, comprising steps of
S51, it is based on the attachment coefficient, determines the electric car work in linear region or nonlinear area；
S52, when the vehicle operation is at linear region, by the active rear steer controller, control the electricity
The rear wheel of electrical automobile obtains the first rear-wheel corner of the electric car；And after being based on the front wheel angle, described first
Corner and the non-linear eight degrees of freedom model of the electric car are taken turns, control is eliminated or reduces the yaw-rate error, with
Make the electric car stable operation；
When the vehicle operation is in nonlinear area, by the active rear steer controller, control is described electronic
The rear wheel of automobile obtains the second rear-wheel corner of the electric car；Meanwhile passing through the direct yaw moment control
Device obtains the wheel tyre power of the electric car, and generates compensation yaw moment based on the wheel tyre power；And based on institute
State front wheel angle, the second rear-wheel corner, the compensation yaw moment and the non-linear eight degrees of freedom mould of the electric car
Type, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
Further, the first rear-wheel corner is the multinomial about the first saturation function；The second rear-wheel corner is
Multinomial about the second saturation function；The compensation yaw moment is the multinomial about sign function；Wherein, described first
Saturation function and second saturation function are specially the saturation function about the first sliding-mode surface integral operator, the sign function
Saturation function specially about the second sliding-mode surface integral operator.
Specifically, for step S51, the attachment coefficient is adhesive force and wheel normal direction (direction vertical with road surface)
The ratio of pressure.It can regard the confficient of static friction between tire and road surface as.This coefficient is bigger, available adhesive force
Bigger, automobile is just less susceptible to skid.The size of attachment coefficient depends primarily on the type and dry condition on road surface, and
There is relationship with structure, tread contour and the travel speed of tire.In the present embodiment, when the attachment coefficient remains unchanged
When, determine that the vehicle operation in linear region, when the attachment coefficient changes, determines the vehicle operation non-thread
Property region；Certainly, in practical applications, the attachment coefficient can be based on according to ARS the and DYC integrated control system of vehicle to define
Vehicle operation is in linear region or nonlinear area.
Further, for step S52, below with reference to setting for active rear steer controller and direct yaw moment control device
Principle is counted, step S52 is introduced:
The design of active rear steer controller uses linear two degrees of freedom (DOF, Degree of Freedom) vehicle mould
Type (as shown in Figure 7), including two freedom degrees of transverse movement and weaving, speed are assumed invariable.2DOF auto model
Main handling characteristic that can well within the scope of overview Vehicular linear, the differential equation are as follows:
In formula, CfAnd CrThe respectively cornering stiffness of front and back wheel, v are vehicle centroid speed, and β is side slip angle, δfAnd δr
Respectively front and back wheel corner.
It designs shown in sliding-mode surface such as formula (21), in order to further decrease tracking error, introduces integral in sliding-mode surface design
Operator:
In formula,For yaw velocity tracking error,c0And c1For undetermined coefficient.The two selection will guarantee feature
Equation λ2+c0λ+c1=0 all characteristic roots are on the left side of complex plane；Then
Formula (20) are substituted into formula (22), while designing sliding formwork control rate with constant speed Reaching Law, evenK>
0, then have
In formula, sgn is sign function, and K is the design parameter of controller, determines that system reaches the speed of slipform design.
In order to slacken or avoid chattering phenomenon caused by switching because of sliding-mode surface, by the sign function sgn (S in formula (24)1)
It is changed to saturation function sat (S1), then rear-wheel corner inputs δrFor
In formula (25), S1The as described first sliding-mode surface integral operator.
In the specific implementation process, due to Vehicular system have very strong nonlinear characteristic, when vehicle enter it is non-linear when,
Four-wheel steering control nargin becomes smaller, and cannot track desired sideway gain well.At this time, it may be necessary to carry out sideway to vehicle
Torque Control, to realize desired sideway gain.Simultaneously in order to improve control effect of the controller under limiting condition, now it is based on
Non-linear Vehicular system designs non-linear yaw moment sliding mode controller.
It is available using yaw velocity as the non-linear Vehicular system of quantity of state, M by formula (7)zIt is horizontal for control input
Put torque.
Wherein,
For nonlinear system, in order to further decrease tracking error, the present embodiment uses integral variable structure control,
Its sliding-mode surface are as follows:
In formula,a0And a1Selection for undetermined coefficient, the two will guarantee characteristic equation λ2+a1λ+a2=0 institute
There is characteristic root on the left side of complex plane.
For single input system, the reaching condition of Sliding mode variable structure control are as follows:
It can then be obtained by formula (27) and formula (28)
In formula,
Designing Sliding mode variable structure control rate is
Formula (30) are substituted into formula (29) to obtain
In order to meet the reaching condition of formula (28), then
In formula, ε is arbitrarily small positive number.
Due to containing discontinuous sign function in controller, the chattering phenomenon of closed-loop system is easily caused, influences to control
Performance.In order to reduce the influence of buffeting, a continuous function is chosen instead of sign function sgn (S2), i.e.,
In formula (33), δ0And δ1For two normal numbers, suitable S is selectedδ, chattering phenomenon can reduce greatly.
Therefore, nonlinear Control inputs yaw moment MzFor
In formula (34), S2The as described second sliding-mode surface integral operator.
That is, when the vehicle operation is at linear region, it is only necessary to pass through the active rear steer controller control
Rear-axle steering processed, and rear-wheel corner and front wheel angle is made to meet equilibrium relationships shown in formula (25), i.e., it is controllable to eliminate or reduce
The yaw-rate error；When the vehicle operation is in nonlinear area, then need the active rear steer controller and
The direct yaw moment control device works at the same time, specifically, the active rear steer controller controls rear-axle steering, and makes
Rear-wheel corner and front wheel angle meet equilibrium relationships shown in formula (25), and direct yaw moment control device generation meets formula
(34) compensate for deficiency that yaw moment, to make up the active rear steer controller, can eliminate or reduce the sideway
Angular speed error.
DYC controller and ARS controller in the present embodiment are defined, according to the work of vehicle in linear region or inelastic region
Domain carries out the scheme of stability control, is DYC+ARS integrated control scheme.It emulates below by Matlab to application scheme
Carry out simulating, verifying:
In this paper simulation process, the horizontal and vertical power of each tire is calculated using Dugoff tire model.According to
8DOF whole vehicle model, the drift angle of each tire are as follows:
Define each tire straight skidding rate are as follows:
Wherein, uiFor the longitudinal velocity of each wheel:
Ignore the effect of aligning torque, longitudinal force of tire FtiWith lateral force FsiIt is respectively as follows:
Wherein, λ is the boundary value introduced, and μ is coefficient of road adhesion, εrFor frictional attenuation coefficient, CsAnd CαIt is respectively
Longitudinal tire stiffness and lateral rigidity.
The simulation parameter of vehicle dynamic model is as shown in table 1.
Table 1
Figure 10 A- Figure 10 D indicates that vehicle travels the simulation result at high attachment road surface, steering angle with the speed of 30m/s
Input is as shown in figure 8, for when speed v=30m/s and input steering angle when attachment coefficient is μ=0.85.
Figure 11 A- Figure 11 D and Figure 12 A- Figure 12 C indicates that vehicle is imitative at low attachment road surface with the speed traveling of 30m/s
It is true as a result, steering angle input is as shown in figure 9, for when speed v=30m/s and input steering angle when attachment coefficient is μ=0.45.
System (the ARS+DYC integrated control system i.e. in the present embodiment of tape controller it can be seen from Figure 10 A and Figure 10 B
System) can accurate track reference model (the i.e. described linear two degrees of freedom vehicle dynamic model), side slip angle also much smaller than
Unsteered system, wherein " not controlling ", which refers to, does not carry out coordinating pipe to each safety control system of vehicle in the prior art
It manages, there may be couple and reduce vehicle performance between each security system.Side slip angle is bigger, shows that vehicle occurs
A possibility that unstability situation, is bigger.Therefore, the system with control improves the stability margin of vehicle, is better than unsteered system.
Simultaneously as coefficient of road adhesion is higher, steering angle is smaller, vehicle groundwork is in linear region.By Figure 10 C and Figure 10 D
It can be seen that active rear steer controller individually works, the output of DYC controller is smaller, is not acted upon.This shows emulation knot
Fruit demonstrates the validity of integrated manipulator, is consistent with the mentality of designing of controller.That is, when vehicle operation is at linear region,
The work of ARS controller, DYC controller do not work to reduce energy consumption and longitudinal intervention.
It can be seen from Figure 11 A and Figure 11 B in low attachment road surface operating condition, there are unstability feelings in unsteered Vehicular system
The side slip angle of condition, the Vehicular system of control is maintained to a lesser extent.At this point, since coefficient of road adhesion is lower, turns to
Angle is larger, and Vehicular system enters nonlinear area, and ARS controller control effect deteriorates, fails accurately to track desired value.At this point,
DYC controller in ARS+DYC integrated manipulator it can be seen from Figure 11 D has certain output, illustrates that DYC controller starts
It works to make up the deficiency of ASR controller.Finally, integrated manipulator is enable preferably to track desired value.Meanwhile by Figure 11 D
As can be seen that the rear-wheel corner output phase of ASR controller and integrated manipulator is same, this shows that DYC controller only controls ARS
Device plays compensating action.That is, when ARS controller can complete independently tracing task when, DYC controller does not work；When ARS is controlled
Device can not complete independently tracing task when, the insufficient part of gain is then by DYC controller compensation.
Figure 12 A- Figure 12 C is the simulation result comparison diagram of DYC controller and integrated manipulator.It can be seen by simulation result
Out, DYC controller and ARS+DYC integrated manipulator can track reference model (as illustrated in fig. 12), but DYC control well
The side slip angle of device is greater than integrated manipulator (as shown in Figure 12 B).Meanwhile yaw moment needed for DYC controller is much big
In integrated manipulator yaw moment (as indicated in fig. 12 c).This shows that integrated manipulator is reducing DYC controller side slip angle
Meanwhile longitudinally controlled control nargin is improved, further to provide possibility using longitudinally controlled stable vehicle control system.
By above-mentioned simulation result it is found that in the integrated control scheme that the present embodiment is proposed, ARS controller and DYC control
Device is working；In vehicle operation at linear region, ARS controller plays a leading role and (works independently), reduces because vertical
It is panic to the variation of speed caused by pro-active intervention, energy consumption and driver.Meanwhile the side slip angle of vehicle is reduced, it mentions
The stability margin of vehicle is risen.When vehicle enters nonlinear area, the DYC controller in integrated manipulator starts to act on, with
The insufficient part of ARS controller gain is compensated, meets the needs of vehicle maneuverability.Meanwhile integrated manipulator reduces independent DYC
The yaw moment demand of controller reduces the longitudinal intervention degree and energy consumption of vehicle.The control of integrated control system is imitated
Control stability of the vehicle under limiting condition is effectively promoted better than the control system for individually using ARS and DYC in fruit, drops
Low yaw moment demand and the longitudinal producing level for reducing vehicle, further to utilize longitudinally controlled stable vehicle control
System provides nargin.
To sum up, the present invention program is directed to electric car Handling stability control problem, ARS controller and DYC are controlled
Device processed has carried out integrated control.ARS controller is designed using linear sliding mode variable-structure control, can satisfy vehicle in linear region
Interior stability control problem.For vehicle in the stability control problem of nonlinear area, non-linear DYC sliding formwork control is devised
Device processed, with control performance of the lifting controller under nonlinear area and limiting condition.The collection of ARS controller and DYC controller
It is to make full use of crosswise joint nargin at control target, reduces longitudinally controlled.That is, when ARS controller being capable of complete independently tracking
When task, DYC controller does not work；When ARS controller can not complete independently tracing task when, the insufficient part of gain then by
DYC controller compensation.
Embodiment two
Based on the same inventive concept, Figure 13 is please referred to, the embodiment of the invention also provides a kind of four motorized wheels are electronic
Automobile stability control system, the system comprises steps:
Steering wheel angle and speed acquiring unit 1301, for when four-wheel independent steering electric car it is in running order and
When needing to turn to, the steering wheel angle and speed of the electric car are obtained；Wherein, the speed is variable velocity；
Variable ratio acquiring unit 1302 is obtained for being based on the speed and speed transmission ratio mathematical model in difference
Variable ratio under speed between the steering wheel of the electric car and rear-wheel corner；
Front wheel angle acquiring unit 1303 obtains the preceding rotation of the electric car for being based on the steering wheel angle
Angle；
Vehicle-state acquiring unit 1304, for being based on variable ratio vehicle ideal model, the speed and the front-wheel
Corner obtains the vehicle perfect condition of the electric car；Meanwhile based on the non-linear eight degrees of freedom model of electric car, described
Speed and the front wheel angle obtain the vehicle virtual condition of the electric car；And then obtain the vehicle virtual condition phase
For the vehicle-state error of the vehicle perfect condition；
Stability control unit 1305 is used for after obtaining the vehicle-state error, when the electric car works
In nonlinear area, pass through the active rear steer controller and direct yaw moment control device of the electric car, control
The vehicle-state error is eliminated or reduces, so that the electric car stable operation；When the electric car works linear
When region, by the active rear steer controller, control is eliminated or reduces the vehicle-state error, so that described electronic
Vehicle running stability.
In the specific implementation process, the active rear steer controller is by linear sliding mode control module structure；Institute
Direct yaw moment control device is stated by nonlinear sliding mode control module structure.
Further, the variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model,
Please refer to Figure 14, the vehicle-state acquiring unit 1304, comprising:
Coefficient of road adhesion obtains module 1304-1, for obtaining the attachment coefficient of electric car institute track；
Vehicle-state obtains module 1304-2, for being based on the variable ratio two degrees of freedom vehicle dynamic model, institute
Attachment coefficient, the speed and the front wheel angle are stated, the expectation yaw velocity of the electric car is obtained；Meanwhile it being based on
The non-linear eight degrees of freedom model of electric car, the speed and the front wheel angle, obtain the practical sideway of the electric car
Angular speed；And then obtain yaw-rate error of the practical yaw velocity relative to the expectation yaw velocity.
In the specific implementation process, referring still to Figure 14, the stability control unit 1305, comprising:
Working region determining module 1305-1 determines that the electric car work is online for being based on the attachment coefficient
Property region or nonlinear area；
Stability control module 1305-2, for passing through the Active Rear when the vehicle operation is at linear region
Steering controller controls the rear wheel of the electric car, obtains the first rear-wheel corner of the electric car；And based on institute
Front wheel angle, the first rear-wheel corner and the non-linear eight degrees of freedom model of the electric car are stated, control is eliminated or reduced
The yaw-rate error, so that the electric car stable operation；
When the vehicle operation is in nonlinear area, by the active rear steer controller, control is described electronic
The rear wheel of automobile obtains the second rear-wheel corner of the electric car；Meanwhile passing through the direct yaw moment control
Device obtains the wheel tyre power of the electric car, and generates compensation yaw moment based on the wheel tyre power；And based on institute
State front wheel angle, the second rear-wheel corner, the compensation yaw moment and the non-linear eight degrees of freedom mould of the electric car
Type, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
Further, the first rear-wheel corner is the multinomial about the first saturation function；The second rear-wheel corner is
Multinomial about the second saturation function；The compensation yaw moment is the multinomial about sign function；Wherein, described first
Saturation function and second saturation function are specially the saturation function about the first sliding-mode surface integral operator, the sign function
Saturation function specially about the second sliding-mode surface integral operator.
As described above, above-mentioned electric car stabilitrak is for realizing above-mentioned electric car stability control
Method processed, so, the course of work of the system and one or more embodiments of the above method are consistent, just no longer go to live in the household of one's in-laws on getting married one by one herein
It states.
It should be understood by those skilled in the art that, the embodiment of the present invention can provide as method, system or computer program
Product.Therefore, complete hardware embodiment, complete software embodiment or reality combining software and hardware aspects can be used in the present invention
Apply the form of example.Moreover, it wherein includes the computer of computer usable program code that the present invention, which can be used in one or more,
The computer program implemented in usable storage medium (including but not limited to magnetic disk storage, CD-ROM, optical memory etc.) produces
The form of product.
The present invention be referring to according to the method for the embodiment of the present invention, the process of equipment (system) and computer program product
Figure and/or block diagram describe.It should be understood that every one stream in flowchart and/or the block diagram can be realized by computer program instructions
The combination of process and/or box in journey and/or box and flowchart and/or the block diagram.It can provide these computer programs
Instruct the processor of general purpose computer, special purpose computer, Embedded Processor or other programmable data processing devices to produce
A raw machine, so that being generated by the instruction that computer or the processor of other programmable data processing devices execute for real
The device for the function of being specified in present one or more flows of the flowchart and/or one or more blocks of the block diagram.
These computer program instructions, which may also be stored in, is able to guide computer or other programmable data processing devices with spy
Determine in the computer-readable memory that mode works, so that it includes referring to that instruction stored in the computer readable memory, which generates,
Enable the manufacture of device, the command device realize in one box of one or more flows of the flowchart and/or block diagram or
The function of being specified in multiple boxes.
These computer program instructions also can be loaded onto a computer or other programmable data processing device, so that counting
Series of operation steps are executed on calculation machine or other programmable devices to generate computer implemented processing, thus in computer or
The instruction executed on other programmable devices is provided for realizing in one or more flows of the flowchart and/or block diagram one
The step of function of being specified in a box or multiple boxes.
Although preferred embodiments of the present invention have been described, it is created once a person skilled in the art knows basic
Property concept, then additional changes and modifications can be made to these embodiments.So it includes excellent that the following claims are intended to be interpreted as
It selects embodiment and falls into all change and modification of the scope of the invention.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range.In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (4)
1. a kind of four motorized wheels electric car stability control method, which is characterized in that the method includes the steps:
S1, when four-wheel independent steering electric car is in running order and needs to turn to, obtain the direction of the electric car
Disk corner and speed；Wherein, the speed is variable velocity；
S2, it is based on the speed and speed transmission ratio mathematical model, obtains the steering wheel of the electric car under different speeds
Variable ratio between front wheel angle；
S3, it is based on the steering wheel angle, obtains the front wheel angle of the electric car；
S4, it is based on variable ratio vehicle ideal model, the speed and the front wheel angle, obtains the vehicle of the electric car
Perfect condition；Meanwhile it being based on the non-linear eight degrees of freedom model of electric car, the speed and the front wheel angle, described in acquisition
The vehicle virtual condition of electric car；And then obtain vehicle shape of the vehicle virtual condition relative to the vehicle perfect condition
State error, wherein the non-linear eight degrees of freedom model specifically includes vertical and horizontal movement, the weaving, inclination of vehicle body
Movement and the rotational motion of four wheels, in which:
Longitudinal movement equation:
Transverse movement equation:
Weaving equation:
Roll motion equation:
The vehicle wheel rotation equation of motion:With i=fl, fr, rl, rr
In above-mentioned equation, m is complete vehicle quality, msFor spring carried mass, U is longitudinal velocity, and V is lateral velocity, and r is yaw angle speed
Degree,For angle of heel, p is roll velocity, lfAnd lrRespectively distance of the vehicle's center of gravity to antero posterior axis, TfAnd TrRespectively front and back
Wheelspan, e are distance of the spring load-carrying heart to roll axis, IzAnd IxRespectively rotary inertia of the vehicle around z-axis and roll axis, IxzFor spring
The mounted mass product of inertia, IwFor tyre rotation inertia, RwFor tire radius, ωiFor tyre rotation angular speed, TdiAnd TbiRespectively make
With the driving moment and braking moment on tire,WithRespectively roll stiffness and inclination resistance, FxiAnd FyiRespectively edge
The tire force of X and Y-direction, wherein i=fl indicates that the near front wheel, i=fr indicate that off-front wheel, i=rl indicate left rear wheel, i=rr table
Show off hind wheel；
S5, after obtaining the vehicle-state error, when electric car work is in nonlinear area, pass through the electricity
The active rear steer controller and direct yaw moment control device of electrical automobile, control are eliminated or are reduced the vehicle-state and misses
Difference, so that the electric car stable operation；When the electric car work at linear region, pass through the Active Rear turn
To controller, control is eliminated or reduces the vehicle-state error, so that the electric car stable operation；
Wherein, the active rear steer controller is by linear sliding mode control module structure；The direct yaw moment control
Device processed is by nonlinear sliding mode control module structure；
Wherein, the variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, which passes
Moving than two degrees of freedom vehicle dynamic model includes two freedom degrees of transverse movement and weaving, and the step S4 includes following
Step:
S41, the attachment coefficient for obtaining electric car institute track；
S42, based on the variable ratio two degrees of freedom vehicle dynamic model, the attachment coefficient, the speed and it is described before
Corner is taken turns, the expectation yaw velocity of the electric car is obtained；Meanwhile based on the non-linear eight degrees of freedom model of electric car,
The speed and the front wheel angle obtain the practical yaw velocity of the electric car；And then obtain the practical sideway
Yaw-rate error of the angular speed relative to the expectation yaw velocity；
Wherein, the step S5, comprising steps of
S51, it is based on the attachment coefficient, determines the electric car work in linear region or nonlinear area；
S52, when the vehicle operation is at linear region, pass through the active rear steer controller, control the electronic vapour
The rear wheel of vehicle obtains the first rear-wheel corner of the electric car；And it is rotated after being based on the front wheel angle, described first
Angle and the non-linear eight degrees of freedom model of the electric car, control is eliminated or reduces the yaw-rate error, so that institute
State electric car stable operation；
When the vehicle operation is in nonlinear area, by the active rear steer controller, the electric car is controlled
Rear wheel, obtain the second rear-wheel corner of the electric car；Meanwhile by the direct yaw moment control device, obtain
The wheel tyre power of the electric car is taken, and compensation yaw moment is generated based on the wheel tyre power；And based on before described
Take turns corner, the second rear-wheel corner, the compensation yaw moment and the non-linear eight degrees of freedom model of the electric car, control
System is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
2. electric car stability control method as described in claim 1, which is characterized in that the first rear-wheel corner is to close
In the multinomial of the first saturation function；The second rear-wheel corner is the multinomial about the second saturation function；The compensation is horizontal
Putting torque is the multinomial about sign function；Wherein, first saturation function and second saturation function are specially to close
In the saturation function of the first sliding-mode surface integral operator, the sign function is specially the saturation about the second sliding-mode surface integral operator
Function；
Wherein, the first sliding-mode surface integral operator are as follows:In formula,For yaw velocity tracking error,R is practical yaw velocity, rdIt is expected yaw velocity, c0And c1For undetermined coefficient and the two selection will guarantee spy
Levy equation λ2+c0λ+c1=0 all characteristic roots are on the left side of complex plane；
Wherein, the second sliding-mode surface integral operator are as follows:In formula,R is practical yaw angle speed
Degree, rdIt is expected yaw velocity, a0And a1Selection for undetermined coefficient, the two will guarantee characteristic equation λ2+a1λ+a2=0 institute
There is characteristic root on the left side of complex plane.
3. a kind of four motorized wheels electric car stabilitrak, which is characterized in that the system comprises steps:
Steering wheel angle and speed acquiring unit, for when four-wheel independent steering electric car is in running order and needs to turn to
When, obtain the steering wheel angle and speed of the electric car；Wherein, the speed is variable velocity；
Variable ratio acquiring unit obtains the institute under different speeds for being based on the speed and speed transmission ratio mathematical model
State the variable ratio between the steering wheel of electric car and front wheel angle；
Front wheel angle acquiring unit obtains the front wheel angle of the electric car for being based on the steering wheel angle；
Vehicle-state acquiring unit is obtained for being based on variable ratio vehicle ideal model, the speed and the front wheel angle
The vehicle perfect condition of the electric car；Meanwhile based on the non-linear eight degrees of freedom model of electric car, the speed and described
Front wheel angle obtains the vehicle virtual condition of the electric car；And then the vehicle virtual condition is obtained relative to the vehicle
The vehicle-state error of perfect condition, wherein the non-linear eight degrees of freedom model specifically includes the vertical and horizontal of vehicle body
Movement, weaving, the rotational motion of roll motion and four wheels, in which:
Longitudinal movement equation:
Transverse movement equation:
Weaving equation:
Roll motion equation:
The vehicle wheel rotation equation of motion:With i=fl, fr, rl, rr
In above-mentioned equation, m is complete vehicle quality, msFor spring carried mass, U is longitudinal velocity, and V is lateral velocity, and r is yaw angle speed
Degree,For angle of heel, p is roll velocity, lfAnd lrRespectively distance of the vehicle's center of gravity to antero posterior axis, TfAnd TrRespectively front and back
Wheelspan, e are distance of the spring load-carrying heart to roll axis, IzAnd IxRespectively rotary inertia of the vehicle around z-axis and roll axis, IxzFor spring
The mounted mass product of inertia, IwFor tyre rotation inertia, RwFor tire radius, ωiFor tyre rotation angular speed, TdiAnd TbiRespectively make
With the driving moment and braking moment on tire,WithRespectively roll stiffness and inclination resistance, FxiAnd FyiRespectively edge
The tire force of X and Y-direction, wherein i=fl indicates that the near front wheel, i=fr indicate that off-front wheel, i=rl indicate left rear wheel, i=rr table
Show off hind wheel；
Stability control unit is used for after obtaining the vehicle-state error, when the electric car works non-linear
When region, by the active rear steer controller and direct yaw moment control device of the electric car, control is eliminated or is subtracted
The small vehicle-state error, so that the electric car stable operation；When the electric car work at linear region, lead to
The active rear steer controller is crossed, the vehicle-state error is eliminated or reduced in control, so that the electric car is stablized
Operation；
Wherein, the active rear steer controller is by linear sliding mode control module structure；The direct yaw moment control
Device processed is by nonlinear sliding mode control module structure；
Wherein, the variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, which passes
Moving than two degrees of freedom vehicle dynamic model includes two freedom degrees of transverse movement and weaving, and the vehicle-state obtains single
Member, comprising:
Coefficient of road adhesion obtains module, for obtaining the attachment coefficient of electric car institute track；
Vehicle-state obtain module, for based on the variable ratio two degrees of freedom vehicle dynamic model, the attachment coefficient,
The speed and the front wheel angle obtain the expectation yaw velocity of the electric car；Meanwhile it is non-thread based on electric car
Property eight degrees of freedom model, the speed and the front wheel angle, obtain the practical yaw velocity of the electric car；And then it obtains
Take the practical yaw velocity relative to the yaw-rate error of the expectation yaw velocity；
Wherein, the stability control unit, comprising:
Working region determining module, for being based on the attachment coefficient, determine electric car work linear region still
Nonlinear area；
Stability control module, for when the vehicle operation is at linear region, by the active rear steer controller,
The rear wheel for controlling the electric car obtains the first rear-wheel corner of the electric car；And based on the front wheel angle,
The yaw angle speed is eliminated or is reduced in the first rear-wheel corner and the non-linear eight degrees of freedom model of the electric car, control
Error is spent, so that the electric car stable operation；
When the vehicle operation is in nonlinear area, by the active rear steer controller, the electric car is controlled
Rear wheel, obtain the second rear-wheel corner of the electric car；Meanwhile by the direct yaw moment control device, obtain
The wheel tyre power of the electric car is taken, and compensation yaw moment is generated based on the wheel tyre power；And based on before described
Take turns corner, the second rear-wheel corner, the compensation yaw moment and the non-linear eight degrees of freedom model of the electric car, control
System is eliminated or reduces the vehicle-state error, so that the electric car stable operation.
4. electric car stabilitrak as claimed in claim 3, which is characterized in that the first rear-wheel corner is to close
In the multinomial of the first saturation function；The second rear-wheel corner is the multinomial about the second saturation function；The compensation is horizontal
Putting torque is the multinomial about sign function；Wherein, first saturation function and second saturation function are specially to close
In the saturation function of the first sliding-mode surface integral operator, the sign function is specially the saturation about the second sliding-mode surface integral operator
Function；
Wherein, the first sliding-mode surface integral operator are as follows:In formula,For yaw velocity tracking error,R is practical yaw velocity, rdIt is expected yaw velocity, c0And c1For undetermined coefficient and the two selection will guarantee spy
Levy equation λ2+c0λ+c1=0 all characteristic roots are on the left side of complex plane；
Wherein, the second sliding-mode surface integral operator are as follows:In formula,R is practical yaw angle speed
Degree, rdIt is expected yaw velocity, a0And a1Selection for undetermined coefficient, the two will guarantee characteristic equation λ2+a1λ+a2=0 institute
There is characteristic root on the left side of complex plane.
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