CN104443022A - Four-wheeled independently-driven electric automobile stability control method and system - Google Patents

Abstract

The invention discloses a four-wheeled independently-driven electric automobile stability control method and system. The technical problem that an ARS safety system and a DYC safety system of an electric automobile in the prior art work simultaneously and accordingly coupling and whole-automobile performance reduction are caused is solved. The four-wheeled independently-driven electric automobile stability control method comprises the steps of obtaining a turn angle of a steering wheel and the speed of an automobile when the automobile turns; obtaining the variable-transmission ratio of the steering wheel to the turn angles of rear wheels based on an automobile speed and automobile speed transmission ratio mathematical model; obtaining the turn angle of front wheels based on the turn angle of the steering wheel; obtaining an ideal state of the automobile based on an ideal variable-transmission ratio model of the automobile, the speed of the automobile and the turn angles of the front wheels; obtaining an actual state of the automobile based on an electric automobile non-linear eight-degree of freedom model, the speed of the automobile and the turn angles of the front wheels; obtaining errors of the actual state of the automobile compared with the ideal state of the automobile; controlling, eliminating or decreasing the errors of the state of the automobile through the ARS and DYC safety systems or the ARS safety system respectively in a nonlinear area or a linear area where the automobile works so as to achieve stable operation of the automobile.

Description

A kind of four motorized wheels electronlmobil stability control method and system

Technical field

The present invention relates to battery-driven car stability control technology field, particularly relate to a kind of four motorized wheels battery-driven car stability control method and system.

Background technology

Along with the development of automotive technology, electronlmobil is owing to adopting high efficiency rechargeable battery or fuel cell to be propulsion source, the pernicious gas of not exhaust emission air itself, even if be scaled the discharge in power plant by institute's consumption of current, outside sulphur removal and particulate, other pollutants also significantly reduces, and greatly improves economic results in society.In addition, relevant research shows, same crude oil, through thick refining, delivers to power plants generating electricity, through being filled with battery, again by battery-operated automobile, its energy utilization efficiency becomes gasoline than through refining, then drives automobile high through spark ignition engine, is therefore conducive to the discharge capacity of economize energy and minimizing carbon dioxide, these advantages just, make the investigation and application of electronlmobil become one " focus " of auto-industry.Current electronlmobil has commercially occupied part automotive market share, and is subject to liking of consumers in general.

In order to improve the road-holding property of electronlmobil, some safety control technologies are applied to automobile, such as direct 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) etc.

Electronlmobil is usually turning to, there will be labile factor at a high speed or in the situations such as bad road of passing through.Accurate, the light steering swivel system evaluating a car of people Chang Huiyong, and steering swivel system directly concerns driving safety and the handling of vehicle.Cornering properties generally can be divided into understeering, neutral steer and oversteer three kinds of situations.Rear-axle steering exist with front-wheel in the same way with reverse two kinds of situations, and both of these case also can show two kinds of diverse cornering propertieses, is exactly increase understeering in the same way in simple terms, oppositely increases oversteer.Vehicle, when low speed driving, suitably can increase ovdersteering by trailing wheel and rotating backward of front-wheel.When the vehicle of running at high speed runs into the situation of urgent modified line, without any under the help of electronic assistant, be easy to the tendency occurring ovdersteering, produce very little but very important turning to front-wheel equidirectional by active rear steer (ARS), the trend of ovdersteering can be made up, automobile can be allowed like this to have better balance.In addition, in order to desalinate the operating skill of navigating mate to the impact of vehicle movement safety, by regulating the stressed of each wheel under the various motoring conditions of vehicle, automobile direct yaw moment (DYC) controls to produce yaw moment and overcomes negative understeer or understeering, thus carries out road-holding property when dynamics Controlling raising automobile travels under the limiting conditions such as high speed and bad road to vehicle on one's own initiative; That is, ARS and DYC is the stability control device that electronlmobil more often adopts.

But these safety control systems (as DYC, ARS) are all that independent design is to solve or to improve the particular characteristic of automobile.When each system works on car load simultaneously, the coupled problem occurred between system can reduce the performance of its car load.That is, in prior art, when electronlmobil direct yaw moment control system and active rear steer system work simultaneously, there will be coupling between two safety systems and reduce vehicle performance.

Summary of the invention

The present invention is directed to exist in prior art when electronlmobil direct yaw moment control system and active rear steer system work simultaneously, there will be coupling between two safety systems and reduce the problem of vehicle performance, there is provided a kind of four motorized wheels electronlmobil stability control method and system, stability during to improve the road-holding property of vehicle when low speed driving and to run at high speed.

On the one hand, embodiments provide a kind of four motorized wheels electronlmobil stability control method, described method comprises step:

S1, when four-wheel independent steering electronlmobil in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described electronlmobil; Wherein, the described speed of a motor vehicle is variable velocity;

S2, based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtain the variable ratio between the bearing circle of described electronlmobil under the different speed of a motor vehicle and trailing wheel corner;

S3, based on described steering wheel angle, obtain the front wheel angle of described electronlmobil;

S4, based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtain the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition;

S5, acquisition described vehicle-state error after, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation; When described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Optionally, described active rear steer controller is by linear sliding mode control module structure; Described direct yaw moment control device is by nonlinear sliding mode control module structure.

Optionally, described variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, and described step S4 comprises the following steps:

S41, obtain the adhesion value of described electronlmobil institute track;

S42, based on described variable ratio two degrees of freedom vehicle dynamic model, described adhesion value, the described speed of a motor vehicle and described front wheel angle, obtain the expectation yaw velocity of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the actual yaw velocity of described electronlmobil is obtained; And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

Optionally, described step S5, comprises step:

S51, based on described adhesion value, determine that described electronlmobil is operated in linearity region or nonlinear area;

S52, when described vehicle operation is in linearity region, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the first trailing wheel corner of described electronlmobil; And based on described front wheel angle, described first trailing wheel corner and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described yaw-rate error, to make described electronlmobil smooth operation;

When described vehicle operation is at nonlinear area, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the second trailing wheel corner of described electronlmobil; Meanwhile, by described direct yaw moment control device, obtain the wheel tyre power of described electronlmobil, and produce compensation yaw moment based on described wheel tyre power; And based on described front wheel angle, described second trailing wheel corner, described compensation yaw moment and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Optionally, described first trailing wheel corner is the multinomial about the first saturation function; Described second trailing wheel corner is the multinomial about the second saturation function; Described compensation yaw moment is the multinomial about symbolic function; Wherein, described first saturation function and described second saturation function are specially the saturation function about the first sliding-mode surface integral operator, and described symbolic function is specially the saturation function about the second sliding-mode surface integral operator.

On the other hand, the embodiment of the present invention additionally provides a kind of four motorized wheels electronlmobil stabilitrak, and described system comprises step:

Steering wheel angle and speed of a motor vehicle acquiring unit, for when four-wheel independent steering electronlmobil in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described electronlmobil; Wherein, the described speed of a motor vehicle is variable velocity;

Variable ratio acquiring unit, for based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtains the variable ratio between the bearing circle of described electronlmobil under the different speed of a motor vehicle and trailing wheel corner;

Front wheel angle acquiring unit, for based on described steering wheel angle, obtains the front wheel angle of described electronlmobil;

Vehicle-state acquiring unit, for based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtains the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition;

Stability control unit, for after the described vehicle-state error of acquisition, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation; When described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Optionally, described active rear steer controller is by linear sliding mode control module structure; Described direct yaw moment control device is by nonlinear sliding mode control module structure.

Optionally, described variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, and described vehicle-state acquiring unit, comprising:

Coefficient of road adhesion acquisition module, for obtaining the adhesion value of described electronlmobil institute track;

Vehicle-state acquisition module, for based on described variable ratio two degrees of freedom vehicle dynamic model, described adhesion value, the described speed of a motor vehicle and described front wheel angle, obtains the expectation yaw velocity of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the actual yaw velocity of described electronlmobil is obtained; And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

Optionally, described stability control unit, comprising:

Work area determination module, for based on described adhesion value, determines that described electronlmobil is operated in linearity region or nonlinear area;

Stability control module, for when described vehicle operation is in linearity region, by described active rear steer controller, controls the rear wheel of described electronlmobil, obtains the first trailing wheel corner of described electronlmobil; And based on described front wheel angle, described first trailing wheel corner and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described yaw-rate error, to make described electronlmobil smooth operation;

When described vehicle operation is at nonlinear area, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the second trailing wheel corner of described electronlmobil; Meanwhile, by described direct yaw moment control device, obtain the wheel tyre power of described electronlmobil, and produce compensation yaw moment based on described wheel tyre power; And based on described front wheel angle, described second trailing wheel corner, described compensation yaw moment and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Optionally, described first trailing wheel corner is the multinomial about the first saturation function; Described second trailing wheel corner is the multinomial about the second saturation function; Described compensation yaw moment is the multinomial about symbolic function; Wherein, described first saturation function and described second saturation function are specially the saturation function about the first sliding-mode surface integral operator, and described symbolic function is specially the saturation function about the second sliding-mode surface integral operator.

The one or more technical schemes provided in the embodiment of the present invention, at least have following technique effect or advantage:

Due in embodiments of the present invention, when four-wheel independent steering battery-driven car is in running order and when needing to turn to, by obtaining steering wheel angle and the speed of a motor vehicle of described battery-driven car, based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtain the variable ratio between the bearing circle of described battery-driven car under the different speed of a motor vehicle and trailing wheel corner, again based on described steering wheel angle, obtain the front wheel angle of described battery-driven car, further, in conjunction with variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtain the vehicle perfect condition of described battery-driven car, meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained, and then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition, finally after the described vehicle-state error of acquisition, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation, when described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation, that is, based on variable ratio vehicle ideal model and the non-linear eight degrees of freedom model of electronlmobil, according to the real work situation of vehicle, as being operated in linearity region or nonlinear area, suitable safety system is selected to carry out stability control, concrete, when vehicle operation is in linearity region, only enable active rear steer controller and carry out safety control, when vehicle operation is at nonlinear area, enable active rear steer controller and direct yaw moment control device carries out safety control simultaneously, to solve in prior art when electronlmobil direct yaw moment control system and active rear steer system work simultaneously, there will be coupling between two safety systems and reduce the technical matters of vehicle performance, road-holding property when improve low vehicle speeds and stability when running at high speed.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the accompanying drawing provided.

The four-wheel independent steering electric vehicle rotary that Figure 1A-Fig. 1 D provides for the embodiment of the present invention is to schematic diagram;

The first four motorized wheels electronlmobil stability control method diagram of circuit that Fig. 2 provides for the embodiment of the present invention;

The second four motorized wheels electronlmobil stability control method diagram of circuit that Fig. 3 provides for the embodiment of the present invention;

The electronlmobil relevant to the speed of a motor vehicle that Fig. 4 provides for the embodiment of the present invention turns to variable ratio diagram of curves;

The SAE conventional coordinates eight degrees of freedom auto model schematic diagram that Fig. 5 provides for the embodiment of the present invention;

The third four motorized wheels electronlmobil stability control method diagram of circuit that Fig. 6 provides for the embodiment of the present invention;

The linear two degrees of freedom auto model that the active rear steer Controller gain variations that Fig. 7 provides for the embodiment of the present invention adopts;

The speed of a motor vehicle v=30m/s that Fig. 8 provides for the embodiment of the present invention and the Matlab that adhesion value is μ=0.85 emulates input redirect angle schematic diagram;

The speed of a motor vehicle v=30m/s that Fig. 9 provides for the embodiment of the present invention and the Matlab that adhesion value is μ=0.45 emulates input redirect angle schematic diagram;

The non-control system that Figure 10 A-Figure 10 D provides for the embodiment of the present invention and ARS+DYC integrated control system simulation result comparison diagram;

The non-control system that Figure 11 A-Figure 11 D provides for the embodiment of the present invention, ARS control system and ARS+DYC integrated control system simulation result comparison diagram;

The DYC control system that Figure 12 A-Figure 12 C provides for the embodiment of the present invention and ARS+DYC integrated control system simulation result comparison diagram;

The first four motorized wheels electronlmobil stabilitrak structured flowchart that Figure 13 provides for the embodiment of the present invention;

The second four motorized wheels electronlmobil stabilitrak structured flowchart that Figure 14 provides for the embodiment of the present invention.

Detailed description of the invention

The embodiment of the present invention is by providing a kind of four-wheel independent steering battery-driven car rotating direction control method, solve exist in prior art when electronlmobil direct yaw moment control system and active rear steer system work simultaneously, there will be coupling between two safety systems and reduce the technical matters of vehicle performance, road-holding property when improve low vehicle speeds and stability when running at high speed.

The technical scheme of the embodiment of the present invention is for solving the problems of the technologies described above, and general thought is as follows:

Embodiments provide a kind of four motorized wheels electronlmobil stability control method, described method comprises step: when four-wheel independent steering electronlmobil is in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described electronlmobil; Wherein, the described speed of a motor vehicle is variable velocity; Based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtain the variable ratio between the bearing circle of described electronlmobil under the different speed of a motor vehicle and trailing wheel corner; Based on described steering wheel angle, obtain the front wheel angle of described electronlmobil; Based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtain the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition; After the described vehicle-state error of acquisition, by active rear steer controller and the direct yaw moment control device of described electronlmobil, or by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Visible, in embodiments of the present invention, based on variable ratio vehicle ideal model and the non-linear eight degrees of freedom model of electronlmobil, according to the real work situation of vehicle, as being operated in linearity region or nonlinear area, suitable safety system is selected to carry out stability control, concrete, when vehicle operation is in linearity region, only enable active rear steer controller and carry out safety control, when vehicle operation is at nonlinear area, enable active rear steer controller and direct yaw moment control device carries out safety control simultaneously, to solve in prior art when electronlmobil direct yaw moment control system and active rear steer system work simultaneously, there will be coupling between two safety systems and reduce the technical matters of vehicle performance, road-holding property when improve low vehicle speeds and stability when running at high speed.

In order to better understand technique scheme, below in conjunction with Figure of description and concrete embodiment, technique scheme is described in detail, the specific features being to be understood that in the embodiment of the present invention and embodiment is the detailed description to technical scheme, instead of the restriction to technical scheme, when not conflicting, the technical characteristic in the embodiment of the present invention and embodiment can combine mutually.

Embodiment one

Embodiments provide a kind of four motorized wheels electronlmobil stability control method; Wherein, four motorized wheels electronlmobil is provided with four, and independently power driven motor and four independently turn to drive motor, namely each wheel is respectively arranged with two drive motor, one is used as power driven, and another is used as and turns to driving, such wheel driving design, the angle that car is rotated becomes large, each wheel can carry out 180 degree and turn to (comprise forward and oppositely each 90 degree), even can transverse shifting, as shown in Figure 1; Concrete, Figure 1A represents car pivot stud, and Figure 1B represents car cross running, Fig. 1 C represents that car deflects in the same way (if former travel direction is for the right, steering direction is still right), Fig. 1 D represents the incorgruous deflection of car (if former travel direction is for the right, steering direction is still left).Then, please refer to Fig. 2, described rotating direction control method comprises step:

S1, when four-wheel independent steering battery-driven car in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described battery-driven car; Wherein, the described speed of a motor vehicle is variable velocity;

S2, based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtain the variable ratio between the bearing circle of described battery-driven car under the different speed of a motor vehicle and trailing wheel corner;

S3, based on described steering wheel angle, obtain the front wheel angle of described battery-driven car;

S4, based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtain the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition;

S5, acquisition described vehicle-state error after, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation; When described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Automotive control system belongs to switching dynamic system, it be by several continuous time subsystem or discrete time subsystem and corresponding switching law form.Due to the effect of switching law, make switched system be different from general continuous time system or discrete-time system, its dynamic characteristics becomes very complicated.A distinguishing feature of the stability of switched system is that the stability of its subsystem is not equal to the stability of whole system.Even if each subsystem of switched system is Linear Time-Invariant System, it is overall is not generally linear system, and belongs to nonlinear system.Sliding mode control theory (SMC, Sliding Mode Control) be the main theory system of variable structure control theory, it has defined the independent theoretical of a whole set of system ensemble, comprising: the method for designing of sliding mode, the various integrated approachs of controller, the stability analysis of system, the reaching condition etc. of system; Variable structure control theory is for solving a kind of good method of Control of Nonlinear Systems problem; Sliding mode control strategy makes state of the system move along sliding-mode surface by the switching of controlling quantity, makes system have invariability when being subject to external disturbance, and therefore Sliding mode variable structure control may be used on processing various nonlinear system; The groundwork of Sliding Mode Variable Structure System is, when state of the system passes through the sliding hyperplane of state space, the structure of controlled reset just changes, thus makes system performance reach certain expectation index; The effect of Sliding Mode Controller is exactly the state of system is driven within the limited time and maintains on this submanifold; The advantage that sliding formwork controls is the uncertainty that can overcome system, has very strong robustness, especially have good control effects to the control of nonlinear system to interference and Unmarried pregnancy.

In specific implementation process, in order to improve the control effects of electronlmobil under limiting condition, described active rear steer controller is by linear sliding mode control module structure; Described direct yaw moment control device is by nonlinear sliding mode control module structure.

In the prior art, mostly using the reference model of linear two degrees of freedom vehicle dynamic model as vehicle stabilization control, to avoid the gain problems of too under vehicle high-speed, and have ignored vehicle gain under the low speed and cross minor issue.But for the automobile with desirable cornering properties, it expects that yaw velocity should reduce with the increase of the speed of a motor vehicle, has larger steering gain under the low speed, has less steering gain at a high speed.To this, in the present embodiment, desirable cornering properties is reached in order to make vehicle as far as possible, adopt variable ratio vehicle ideal model as the reference model of vehicle stabilization control, wherein, described variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, and please refer to Fig. 3, described step S4 comprises the following steps:

S41, obtain the adhesion value of described electronlmobil institute track;

S42, based on described variable ratio two degrees of freedom vehicle dynamic model, described adhesion value, the described speed of a motor vehicle and described front wheel angle, obtain the expectation yaw velocity of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the actual yaw velocity of described electronlmobil is obtained; And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

In specific implementation process, first, the steering wheel angle and the speed of a motor vehicle that obtain vehicle is detected respectively by the steering wheel angle detecting device of vehicle and vehicle speed detector device; Then, according to the mathematical relation of BMW speed and transmitting ratio, draw the transmitting ratio (i.e. described variable ratio) between bearing circle under the different speed of a motor vehicle of vehicle in the present embodiment and trailing wheel corner, after determining described variable ratio, when input direction dish corner just can obtain front wheel angle.Object due to Vehicle Stability Control is the stable state and the transient state response that improve automobile, improve the manoevreability of automobile and the ability of safety and anti-external disturbance, and the yaw velocity of automobile (namely automobile is around the yaw rate of vertical axis) and side slip angle are the important parameters weighing vehicle steadily degree, when side slip angle one timing, if yaw rate reaches a threshold value, illustrate that automobile occurs to survey the dangerous working conditions such as sliding or whipping.Below by the principal parameter using the yaw velocity of vehicle as measurement vehicle-state, step S41 ~ S42 is specifically described:

1) the expectation yaw velocity of four-wheel automobile is obtained based on coefficient of road adhesion

Due in existing conventional art, employing is determined the linear two degrees of freedom vehicle dynamic model of steering gear ratio and cannot be met Vehicle turning stability requirement; For this reason, in the present embodiment, variable ratio two degrees of freedom vehicle dynamic model is adopted to ask for the yaw velocity of expectation, by variable ratio i _vsubstitute stable drive ratio i.Thus, can obtain expecting yaw velocity:

$r_d=\frac{v}{L+K_v{v}^2{i}_v}\frac{{\mathrm{\θ}}_{\mathrm{sw}}}{i_v}=\frac{v}{L+K_v{v}^2}\frac{i{\mathrm{\δ}}_f}{i_v}---\left(1\right)$

In formula, $K_v=\frac{m}{L}(\frac{l_r}{C_f}-\frac{l_f}{C_r}),$ θ _sw＝iδ _f。

In formula (1), v is vehicle centroid speed, K _vfor understeering coefficient, θ _swfor steering wheel angle, δ _ffor front wheel angle, m is complete vehicle quality, l _fand l _rbe respectively center of gravity to axle distance, C _fand C _rbe respectively the cornering stiffness of front and rear wheel, L is front and rear wheel wheelbase.

Current, variable ratio can provide significant effect to steering vehicle turning, significantly improves the road-holding property of chaufeur.In the present embodiment, as shown in Figure 4, for the electric vehicle rotary relevant to the speed of a motor vehicle is to variable ratio diagram of curves, the variable ratio i taked _vkinematics function is relevant with speed of a motor vehicle v; When middle low speed, i _vless, turn to more direct, light, what significantly reduce chaufeur turns to task; When high speed, i _vcomparatively large, turn to the comparatively heavy of change, what increase chaufeur turns to task, improves directional balance.

Because automobile yaw velocity is also subject to the restriction of road surface attachment condition, its limit is relevant with coefficient of road adhesion and the speed of a motor vehicle, shown in (2),

$\left|r\right|\≤\left|r_{\max }\right|=0.85\frac{\mathrm{\μ}\·g}{v}---\left(2\right)$

In formula (2), r is the actual yaw velocity of automobile, r _maxfor the actual yaw velocity maxim of automobile, μ is the nominal friction coefficient (i.e. described adhesion value) between tire and ground, and g is acceleration due to gravity, and v is car degree.

Therefore, after considering the adhesive ability in practical application between vehicle and ground, vehicle expects that yaw velocity is modified to:

$r_d^{*}\text{=min{|}\frac{v}{L+K_v{v}^2}\frac{i{\mathrm{\δ}}_f}{i_v}|,|0.85\frac{\mathrm{\μ}\·g}{v}\left|\right\}\·\mathrm{sgn}\left({\mathrm{\δ}}_f\right)---\left(3\right)$

In formula (3), sgn (δ _f) be symbolic function about front wheel angle.

In real process, in order to prevent the transient state response of Vehicular yaw cireular frequency from occurring larger vibration or overshoot, need expect that yaw velocity carries out first-order filtering to the vehicle in formula (3), finally being expected yaw velocity r _d' be:

$r_d^{\′}\text{=min}\{\left|\frac{v}{L+K_v{v}^2}\frac{i{\mathrm{\δ}}_f}{i_v}\right|,|0.85\frac{\mathrm{\μ}\·g}{v}|\}\·\mathrm{sgn}\left({\mathrm{\δ}}_f\right)\·\frac{1}{1+{\mathrm{\τ}}_{r}s}---\left(4\right)$

In formula (4), s is Laplace operator, τ _rfor yaw velocity delay time, span is (0.1 ~ 0.25) s.

2) the actual yaw velocity of four-wheel automobile is obtained based on electronlmobil non-linear eight degrees of freedom model

In the present embodiment, adopt international automobile IEEE (SAE, Society of AutomotiveEngineers) conventional coordinates (as shown in Figure 5), set up 8 degree of freedom (DOF, Degree of Freedom) auto model, specifically comprise the rotational motion of the vertical and horizontal motion of vehicle body, weaving, roll motion and four wheels, totally 8 degree of freedom, ignore the vertical of car load and luffing.The 8DOF car load equation of motion as follows can be obtained by Fig. 5:

Longitudinal movement equation: $m\stackrel{\·}{U}=\mathrm{mVr}+F_{\mathrm{xfl}}+F_{\mathrm{xfr}}+F_{\mathrm{xrl}}+F_{\mathrm{xrr}}---\left(5\right)$

Cross motion equation: $m\stackrel{\·}{V}=-\mathrm{mUr}-m_{s}e\stackrel{\·}{p}+F_{\mathrm{yfl}}+F_{\mathrm{yfr}}+F_{\mathrm{yrl}}+F_{\mathrm{yrr}}---\left(6\right)$

Weaving equation: $I_z\stackrel{\·}{r}=I_{\mathrm{xz}}\stackrel{\·}{p}+l_f(F_{\mathrm{yfl}}+F_{\mathrm{yfr}})-l_r(F_{\mathrm{yrl}}+F_{\mathrm{yrr}})+\frac{T_r}{2}(F_{\mathrm{xfl}}-F_{\mathrm{xfr}})+\frac{T_r}{2}(F_{\mathrm{xrl}}-F_{\mathrm{xrr}})+-M_z---\left(7\right)$

Roll motion equation:

The vehicle wheel rotation equation of motion: with i=fl, fr, rl, rr (10)

In above-mentioned equation (5) ~ (10), m is complete vehicle quality, m _sfor spring carried mass, U is longitudinal velocity, and V is cross velocity, and r is yaw velocity, for angle of roll, p is bank velocity, l _fand l _rbe respectively the distance of vehicle's center of gravity to antero posterior axis, T _fand T _rbe respectively wheel base, e is the distance of the spring load-carrying heart to roll axis, I _zand I _xbe respectively the rotor inertia of vehicle around z-axis and roll axis, I _xzfor the spring carried mass product of inertia, I _wfor tyre rotation inertia, R _wfor tire radius, ω _ifor tyre rotation cireular frequency, T _diand T _bibe respectively and act on drive torque on tire and lock torque, with be respectively roll rate and roll resistance, F _xiand F _yibe respectively the tire force along X and Y-direction, wherein, i=fl represents the near front wheel, i=fr represents off front wheel, i=rl represents left rear wheel, i=rr represents off hind wheel.

Tire force F _xiand F _yican be obtained by coordinate transform:

F _xi＝F _{t i}cos δ _i-F _sisinδ _iwith i＝fl,fr,rl,rr (11)

F _yi＝F _tisin δ _i+F _sicos δ _iwith i＝fl,fr,rl,rr (12)

Wherein, F _tiand F _sibe respectively longitudinal tire force and side direction tire force, δ _ifor four-wheel corner.

Consider the load transfer because vertical and horizontal acceleration/accel causes, the nominal vertical load of tire can be expressed as follows:

Wherein, l=a+b is wheelbase; A is the distance of front-wheel to barycenter; B is the distance of trailing wheel to barycenter; h _cgfor spring carried mass height of gravitational center; K _r=K _f/ (K _f+ K _r), K _fand K _rbe respectively front and back roll rate; a _yfor the transverse acceleration at barycenter place, be expressed as r is yaw velocity, and v is the speed of a motor vehicle, K _vfor automobile understeering gradient, θ _swfor front wheel angle, i is for determine steering gear ratio.

Automobile is as follows relative to the coordinate on ground:

$\stackrel{\·}{X}=U\cos \mathrm{\ψ}-V\sin \mathrm{\ψ}---\left(17\right)$

$\stackrel{\·}{Y}=-U\sin \mathrm{\ψ}-V\cos \mathrm{\ψ}---\left(18\right)$

In formula (17) and formula (18), ψ is the yaw angle at vehicle centroid place, is expressed as the actual yaw velocity of vehicle and the product of time.

Under the speed of a motor vehicle of known electric electrical automobile and the prerequisite of front wheel angle, just can calculate the actual yaw velocity of described electronlmobil based on formula (5) ~ (18); And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

Further, please refer to Fig. 6, successively after execution of step S41 and step S42, perform step S5, described step S5, comprises step:

S51, based on described adhesion value, determine that described electronlmobil is operated in linearity region or nonlinear area;

S52, when described vehicle operation is in linearity region, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the first trailing wheel corner of described electronlmobil; And based on described front wheel angle, described first trailing wheel corner and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described yaw-rate error, to make described electronlmobil smooth operation;

When described vehicle operation is at nonlinear area, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the second trailing wheel corner of described electronlmobil; Meanwhile, by described direct yaw moment control device, obtain the wheel tyre power of described electronlmobil, and produce compensation yaw moment based on described wheel tyre power; And based on described front wheel angle, described second trailing wheel corner, described compensation yaw moment and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Further, described first trailing wheel corner is the multinomial about the first saturation function; Described second trailing wheel corner is the multinomial about the second saturation function; Described compensation yaw moment is the multinomial about symbolic function; Wherein, described first saturation function and described second saturation function are specially the saturation function about the first sliding-mode surface integral operator, and described symbolic function is specially the saturation function about the second sliding-mode surface integral operator.

Concrete, for step S51, described adhesion value is adhesive ability and the ratio of wheel normal direction (direction vertical with road surface) pressure.It can regard the coefficient of static friction between tire and road surface as.This coefficient is larger, and available adhesive ability is larger, and automobile is more not easy to skid.The size of adhesion value, depends primarily on kind and the dry condition on road surface, and and the structure of tire, tread contour and moving velocity have relation.In the present embodiment, when described adhesion value remains unchanged, determine that described vehicle operation is in linearity region, when described adhesion value changes, determine that described vehicle operation is at nonlinear area; Certainly, in actual applications, vehicle operation can be defined in linearity region or nonlinear area according to ARS and the DYC integrated control system of vehicle based on described adhesion value.

Further, for step S52, below in conjunction with the principle of design of active rear steer controller and direct yaw moment control device, step S52 is introduced:

The design of active rear steer controller adopts linear two degrees of freedom (DOF, Degree of Freedom) auto model (as shown in Figure 7), comprises cross motion and weaving two degree of freedom, and speed of a motor vehicle hypothesis is invariable.2DOF auto model can main maneuvering characteristics well within the scope of overview Vehicular linear, and its differential equation is as follows:

$\stackrel{\·}{\mathrm{\β}}=-\frac{C_f+C_r}{\mathrm{mv}}\mathrm{\β}-(1+\frac{C_f{l}_f-C_r{l}_r}{{\mathrm{mv}}^2})r+\frac{C_f}{\mathrm{mv}}{\mathrm{\δ}}_f+\frac{C_r}{\mathrm{mv}}{\mathrm{\δ}}_f---\left(19\right)$

$\stackrel{\·}{r}=\frac{C_r{l}_r-C_f{l}_f}{I_z}\mathrm{\β}-\frac{C_r{l}_f^2+C_r{l}_r^2}{I_{z}v}r+\frac{C_f{l}_f}{I_{z}v}{\mathrm{\δ}}_f-\frac{C_r{l}_r}{I_z}{\mathrm{\δ}}_r---\left(20\right)$

In formula, C _fand C _rbe respectively the cornering stiffness of front and back wheel, v is vehicle centroid speed, and β is side slip angle, δ _fand δ _rbe respectively front and back wheel corner.

Design sliding-mode surface, such as formula shown in (21), in order to reduce tracking error further, introduces integral operator in sliding-mode surface design:

$S_1=\stackrel{\·}{e}+c_{0}e+c_1\∫\mathrm{edt}---\left(21\right)$

In formula, for yaw velocity tracking error, c ₀and c ₁for undetermined coefficient.Both choose and will ensure characteristic equation λ ²+ c ₀λ+c ₁all characteristic roots of=0 are all on the left side of complex plane; Then

${\stackrel{\·}{S}}_1=\stackrel{\·\·}{e}+c_0\stackrel{\·}{e}+c_{1}e=\stackrel{\·}{r}-{\stackrel{\·}{r}}_d+c_0\stackrel{\·}{e}+c_{1}e---\left(22\right)$

Formula (20) is substituted into formula (22), simultaneously by constant speed Reaching Law design sliding formwork inverse amplification factor, even ${\stackrel{\·}{S}}_1=-K\·\mathrm{sgn}\left(S_1\right),$ K>0, then have

${\stackrel{\·}{S}}_1=\frac{C_r{l}_r-C_f{l}_f}{I_z}\mathrm{\β}-\frac{C_f{l}_f^2+C_r{l}_r^2}{I_{z}v}r+\frac{C_f{l}_f}{I_z}{\mathrm{\δ}}_f-\frac{C_r{l}_r}{I_z}{\mathrm{\δ}}_r-{\stackrel{\·}{r}}_d+c_0\stackrel{\·}{e}+c_{1}e=-K\·\mathrm{sgn}\left(S_1\right)---\left(23\right)$

${\mathrm{\δ}}_r=\frac{I_z}{C_r{I}_r}(\frac{C_r{l}_r-C_f{l}_f}{I_z}\mathrm{\β}-\frac{C_f{l}_f^2+C_r{l}_r^2}{I_{z}v}r+\frac{C_f{l}_f}{I_z}{\mathrm{\δ}}_f-{\stackrel{\·}{r}}_d+c_0\stackrel{\·}{e}+c_{1}e+K\·\mathrm{sgn}\left(S_1\right))---\left(24\right)$

In formula, sgn is symbolic function, and K is the design parameters of controller, determines the speed that system arrives slipform design.

In order to slacken or avoid because sliding-mode surface switches the chattering phenomenon caused, by the symbolic function sgn (S in formula (24) ₁) make saturation function sat (S into ₁), then trailing wheel corner input δ _rfor

${\mathrm{\δ}}_r=\frac{I_z}{C_r{I}_r}(\frac{C_r{l}_r-C_f{l}_f}{I_z}\mathrm{\β}-\frac{C_f{l}_f^2+C_r{l}_r^2}{I_{z}v}r+\frac{C_f{l}_f}{I_z}{\mathrm{\δ}}_f-{\stackrel{\·}{r}}_d+c_0\stackrel{\·}{e}+c_{1}e+K\·\mathrm{sat}\left(S_1\right))---\left(25\right)$

In formula (25), S ₁be described first sliding-mode surface integral operator.

In specific implementation process, because Vehicular system has very strong nonlinear characteristic, when vehicle enters non-linear, four-wheel steering controls nargin and diminishes, and can not follow the tracks of desired yaw gain well.Now, need to carry out yaw moment control to vehicle, to realize the yaw gain expected.Simultaneously in order to improve the control effects of controller under limiting condition, now design non-linear yaw moment sliding mode controller based on non-linear Vehicular system.

Can be obtained by formula (7) take yaw velocity as the non-linear Vehicular system of quantity of state, M _zfor control inputs yaw moment.

$I_z\stackrel{\·}{r}=F+\frac{1}{I_z}{M}_z,\stackrel{\·}{r}=\frac{1}{I_z}(I_{\mathrm{xz}}\stackrel{\·}{p}+l_f(F_{\mathrm{yfl}}+F_{\mathrm{yfr}})-l_r(F_{\mathrm{yrl}}+F_{\mathrm{yrr}}))+\frac{1}{I_z}{M}_z---\left(26\right)$

Wherein, $M_z=\frac{T_f}{2}(F_{\mathrm{yfl}}-F_{\mathrm{xfr}})+\frac{T_r}{2}(F_{\mathrm{xrl}}-F_{\mathrm{xrr}})$

For nonlinear system, in order to reduce tracking error further, the present embodiment adopts integral variable structure control, and its sliding-mode surface is:

$S_2=\stackrel{\·}{e}+a_{0}e+a_1\∫\mathrm{edt}---\left(27\right)$

In formula, a ₀and a ₁for undetermined coefficient, both choosing will ensure characteristic equation λ ²+ a ₁λ+a ₂all characteristic roots of=0 are all on the left side of complex plane.

For single input system, the reaching condition of Sliding mode variable structure control is:

$S_2\&CenterDot;{\stackrel{\&CenterDot;}{S}}_2<0---(28)$

Then can be obtained by formula (27) and formula (28)

$S_2\&CenterDot;{\stackrel{\&CenterDot;}{S}}_2=S_2\&CenterDot;F+S_2\&CenterDot;\frac{1}{I_z}{M}_z\&le;\left|S_2\right|\&CenterDot;\left|F\right|+S_2\&CenterDot;\frac{1}{I_z}{M}_z---\left(29\right)$

In formula, $F=\frac{1}{I_z}[I_{\mathrm{xz}}\stackrel{\&CenterDot;}{p}+l_f(F_{\mathrm{yfl}}+F_{\mathrm{yfr}})-l_r(F_{\mathrm{yrl}}+F_{\mathrm{yrr}})]-{\stackrel{\&CenterDot;}{r}}_d+a_0\stackrel{\&CenterDot;}{e}+a_{1}e$

Design Sliding mode variable structure control rate is

Formula (30) is substituted into formula (29) obtain

In order to meet the reaching condition of formula (28), then

In formula, ε is arbitrarily small positive number.

Owing to containing discontinuous symbolic function in controller, easily cause the chattering phenomenon of closed loop system, affect controller performance.In order to reduce the impact of buffeting, choosing a continuous function and replacing symbolic function sgn (S ₂), namely

$S_{\mathrm{\&delta;}}\left(S_2\right)=\frac{S_2}{\left|S_2\right|+{\mathrm{\&delta;}}_0+{\mathrm{\&delta;}}_1\left|e\right|}---\left(33\right)$

In formula (33), δ ₀and δ ₁be two normal numbers, select suitable S _δ, chattering phenomenon can reduce greatly.

Therefore, nonlinear Control input yaw moment M _zfor

$M_z=-\left(I_z\right|\frac{1}{I_z}[I_{\mathrm{xz}}\stackrel{\&CenterDot;}{p}+l_f(F_{\mathrm{yfl}}+F_{\mathrm{yfr}})-l_r(F_{\mathrm{yrl}}+F_{\mathrm{yrr}})]-{\stackrel{\&CenterDot;}{r}}_d+a_0\stackrel{\&CenterDot;}{e}+a_{1}e|+\mathrm{\&epsiv;})\&CenterDot;S_{\mathrm{\&delta;}}\left(S_2\right)---\left(34\right)$

In formula (34), S ₂be described second sliding-mode surface integral operator.

That is, when described vehicle operation is in linearity region, only need to control rear-axle steering by described active rear steer controller, and make trailing wheel corner and front wheel angle meet the equilibrium relationships shown in formula (25), can control eliminate or reduce described yaw-rate error; When described vehicle operation is at nonlinear area, then need described active rear steer controller and described direct yaw moment control device to work simultaneously, concrete, described active rear steer controller controls rear-axle steering, and make trailing wheel corner and front wheel angle meet the equilibrium relationships shown in formula (25), and described direct yaw moment control device produces the compensation yaw moment meeting formula (34), make up the deficiency of described active rear steer controller, just can eliminate or reduce described yaw-rate error.

DYC controller and ARS controller in definition the present embodiment, be operated in linearity region or nonlinear area according to vehicle, carrying out the scheme of stability control, is DYC+ARS integrating control scheme.Below by Matlab emulation, simulating, verifying is carried out to the application's scheme:

In this paper simulation process, Dugoff tire model is utilized to calculate the horizontal and vertical power of each tire.According to 8DOF whole vehicle model, the slip angle of each tire is:

${\mathrm{\&alpha;}}_{\mathrm{fl}}={\mathrm{\&delta;}}_{\mathrm{fl}}-\arctan \left(\frac{V+l_{f}r}{U+0.5T_{f}r}\right)---\left(35\right)$

${\mathrm{\&alpha;}}_{\mathrm{fr}}={\mathrm{\&delta;}}_{\mathrm{fr}}-\arctan \left(\frac{V+l_{f}r}{U-0.5T_{f}r}\right)---\left(36\right)$

${\mathrm{\&alpha;}}_{\mathrm{rl}}={\mathrm{\&delta;}}_{\mathrm{rl}}-\arctan \left(\frac{V-l_{r}r}{U+0.5T_{r}r}\right)---\left(37\right)$

${\mathrm{\&alpha;}}_{\mathrm{rr}}={\mathrm{\&delta;}}_{\mathrm{rr}}-\arctan \left(\frac{V-l_{r}r}{U-0.5T_{r}r}\right)---\left(38\right)$

Defining each tire straight skidding rate is:

$S_i=\begin{array}{cc}\left\{\begin{array}{cc}\frac{R_w{\mathrm{\&omega;}}_i-u_i}{u_i},& R_w{\mathrm{\&omega;}}_i<u_i\\ \frac{R_w{\mathrm{\&omega;}}_i-u_i}{R_w{\mathrm{\&omega;}}_i},& R_w{\mathrm{\&omega;}}_i\&GreaterEqual;u_i\end{array}\right.& \mathrm{withi}=\mathrm{fl},\mathrm{fr},\mathrm{rl},\mathrm{rr}\end{array}---\left(39\right)$

Wherein, u _ilongitudinal velocity for each wheel:

$u_{\mathrm{fl}}=(U+\frac{1}{2}{T}_{f}r)\cos {\mathrm{\&delta;}}_{\mathrm{fl}}+(V+l_{f}r)\sin {\mathrm{\&delta;}}_{\mathrm{fl}}---\left(40\right)$

$u_{\mathrm{fr}}=(U-\frac{1}{2}{T}_{f}r)\cos {\mathrm{\&delta;}}_{\mathrm{fr}}+(V+l_{f}r)\sin {\mathrm{\&delta;}}_{\mathrm{fr}}---\left(41\right)$

$u_{\mathrm{rl}}=(U+\frac{1}{2}{T}_{r}r)\cos {\mathrm{\&delta;}}_{\mathrm{rl}}+(V-l_{r}r)\sin {\mathrm{\&delta;}}_{\mathrm{rl}}---\left(42\right)$

$u_{\mathrm{rr}}=(U-\frac{1}{2}{T}_{r}r)\cos {\mathrm{\&delta;}}_{\mathrm{rr}}+(V-l_{r}r)\sin {\mathrm{\&delta;}}_{\mathrm{rr}}---\left(43\right)$

Ignore the effect of aligning torque, longitudinal force of tire F _tiwith side force F _sibe respectively:

$F_{\mathrm{ti}}=\frac{C_s{S}_i}{1-S_i}f\left(\mathrm{\&lambda;}\right)---\left(44\right)$

$F_{\mathrm{si}}=\frac{C_{\mathrm{\&alpha;}}\tan {\mathrm{\&alpha;}}_i}{1-S_i}f\left(\mathrm{\&lambda;}\right)---\left(45\right)$

$f\left(\mathrm{\&lambda;}\right)=\left\{\begin{array}{cc}\mathrm{\&lambda;}(2-\mathrm{\&lambda;})& \mathrm{if\&lambda;}<1\\ 1& \mathrm{if\&lambda;}\&GreaterEqual;1\end{array}\right.---\left(46\right)$

$\mathrm{\&lambda;}=\frac{\mathrm{\&mu;}{F}_{\mathrm{zi}}[1-{\mathrm{\&epsiv;}}_r{u}_i\sqrt{S_i^2+{\tan }^2{\mathrm{\&alpha;}}_i}](1-S_i)}{2\sqrt{C_s^2{S}_i^2+C_{\mathrm{\&alpha;}}^2{\tan }^2{\mathrm{\&alpha;}}_i}}---\left(47\right)$

Wherein, λ is the boundary value introduced, and μ is coefficient of road adhesion, ε _rfor frictional attenuation coefficient, C _sand C _αlongitudinal tire stiffness and lateral rigidity respectively.

The simulation parameter of vehicle dynamic model is as shown in table 1.

Table 1

Figure 10 A-Figure 10 D represents, vehicle with the speeds of 30m/s height attachment road surface time simulation result, deflection angle input as shown in Figure 8, for as speed of a motor vehicle v=30m/s and adhesion value is μ=0.85 time input redirect angle.

Figure 11 A-Figure 11 D and Figure 12 A-Figure 12 C represents, vehicle with the simulation result of the speeds of 30m/s when low attachment road surface, deflection angle input as shown in Figure 9, for as speed of a motor vehicle v=30m/s and adhesion value is μ=0.45 time input redirect angle.

As can be seen from Figure 10 A and Figure 10 B, the system (i.e. ARS+DYC integrated control system in the present embodiment) of tape controller can accurate tracking reference model (i.e. described linear two degrees of freedom vehicle dynamic model), side slip angle is also much smaller than unsteered system, wherein, " do not control " to refer in prior art and each safety control system of vehicle do not coordinated and managed may there is coupling between each safety system and the problem of reduction vehicle performance.Side slip angle is larger, shows that vehicle occurs that the possibility of unstability situation is larger.Therefore, the system that band controls improves the stability margin of vehicle, is better than unsteered system.Meanwhile, because coefficient of road adhesion is higher, deflection angle is less, vehicle groundwork is in linearity region.Can find out that active rear steer controller works separately by Figure 10 C and Figure 10 D, DYC controller export less, do not work.This shows, the simulation results show validity of integrated manipulator, conforms to the mentality of designing of controller.That is, when vehicle operation is in linearity region, ARS controller works, and DYC controller does not work reduce energy ezpenditure and longitudinally intervene.

As can be seen from Figure 11 A and Figure 11 B, when low attachment road surface operating mode, there is unstability situation in unsteered Vehicular system, the side slip angle of the Vehicular system of control is maintained to a lesser extent.Now, because coefficient of road adhesion is lower, deflection angle is comparatively large, and Vehicular system enters nonlinear area, and ARS controller control effects worsens, and fails accurate tracking expectation value.Now, there is certain output as can be seen from the DYC controller in Figure 11 D, ARS+DYC integrated manipulator, illustrate that DYC controller starts working to make up the deficiency of ASR controller.Finally, integrated manipulator is enable to follow the tracks of expectation value preferably.Meanwhile, export identical as can be seen from Figure 11 D, ASR controller with the trailing wheel corner of integrated manipulator, this shows that DYC controller just plays compensating action to ARS controller.That is, when ARS controller can complete independently tracing task time, DYC controller does not work; When ARS controller can not complete independently tracing task time, the part of gain deficiency is then by DYC controller compensation.

Figure 12 A-Figure 12 C is the simulation result comparison diagram of DYC controller and integrated manipulator.As can be seen from simulation result, DYC controller and ARS+DYC integrated manipulator all can track reference models (as illustrated in fig. 12) well, but the side slip angle of DYC controller is greater than integrated manipulator (as shown in Figure 12 B).Meanwhile, the yaw moment needed for DYC controller is far longer than integrated manipulator yaw moment (as indicated in fig. 12 c).This shows that integrated manipulator is while reduction DYC controller side slip angle, improves the control nargin longitudinally controlled, stablizes vehicle control system provide possibility for utilizing longitudinally control further.

From above-mentioned simulation result, in the integrating control scheme that the present embodiment proposes, ARS controller and DYC controller are all in work; Vehicle operation in linearity region time, ARS controller plays a leading role (namely working independently), reduce cause because of longitudinal pro-active intervention speed of a motor vehicle change, energy ezpenditure and chaufeur panic.Meanwhile, reduce the side slip angle of vehicle, improve the stability margin of vehicle.When vehicle enters nonlinear area, the DYC controller in integrated manipulator starts effect, to compensate the part of ARS controller gain deficiency, meets the demand of vehicle maneuverability.Meanwhile, integrated manipulator reduces the yaw moment demand of independent DYC controller, and the longitudinal direction reducing vehicle intervenes degree and energy ezpenditure.The control effects of integrated control system is better than the control system adopting separately ARS and DYC, effectively improve the road-holding property of vehicle under limiting condition, reduce yaw moment demand and reduce longitudinal producing level of vehicle, stablize vehicle control system for utilizing longitudinally control further and provide nargin.

Generally speaking, the present invention program, for electronlmobil Handling stability control problem, has carried out integrating control to ARS controller and DYC controller.Adopt linear sliding mode variable-structure control design ARS controller, the stability control problem of vehicle in linearity region can be met.For the stability control problem of vehicle at nonlinear area, devise non-linear DYC sliding mode controller, with the controller performance of lifting controller under nonlinear area and limiting condition.The integrating control target of ARS controller and DYC controller, for making full use of crosswise joint nargin, reduces longitudinally to control.That is, when ARS controller can complete independently tracing task time, DYC controller does not work; When ARS controller can not complete independently tracing task time, the part of gain deficiency is then by DYC controller compensation.

Embodiment two

Based on same inventive concept, please refer to Figure 13, the embodiment of the present invention additionally provides a kind of four motorized wheels electronlmobil stabilitrak, and described system comprises step:

Steering wheel angle and speed of a motor vehicle acquiring unit 1301, for when four-wheel independent steering electronlmobil in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described electronlmobil; Wherein, the described speed of a motor vehicle is variable velocity;

Variable ratio acquiring unit 1302, for based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtains the variable ratio between the bearing circle of described electronlmobil under the different speed of a motor vehicle and trailing wheel corner;

Front wheel angle acquiring unit 1303, for based on described steering wheel angle, obtains the front wheel angle of described electronlmobil;

Vehicle-state acquiring unit 1304, for based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtains the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition;

Stability control unit 1305, for after the described vehicle-state error of acquisition, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation; When described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

In specific implementation process, described active rear steer controller is by linear sliding mode control module structure; Described direct yaw moment control device is by nonlinear sliding mode control module structure.

Further, described variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, please refer to Figure 14, and described vehicle-state acquiring unit 1304, comprising:

Coefficient of road adhesion acquisition module 1304-1, for obtaining the adhesion value of described electronlmobil institute track;

Vehicle-state acquisition module 1304-2, for based on described variable ratio two degrees of freedom vehicle dynamic model, described adhesion value, the described speed of a motor vehicle and described front wheel angle, obtains the expectation yaw velocity of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the actual yaw velocity of described electronlmobil is obtained; And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

In specific implementation process, still please refer to Figure 14, described stability control unit 1305, comprising:

Work area determination module 1305-1, for based on described adhesion value, determines that described electronlmobil is operated in linearity region or nonlinear area;

Stability control module 1305-2, for when described vehicle operation is in linearity region, by described active rear steer controller, controls the rear wheel of described electronlmobil, obtains the first trailing wheel corner of described electronlmobil; And based on described front wheel angle, described first trailing wheel corner and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described yaw-rate error, to make described electronlmobil smooth operation;

When described vehicle operation is at nonlinear area, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the second trailing wheel corner of described electronlmobil; Meanwhile, by described direct yaw moment control device, obtain the wheel tyre power of described electronlmobil, and produce compensation yaw moment based on described wheel tyre power; And based on described front wheel angle, described second trailing wheel corner, described compensation yaw moment and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

Further, described first trailing wheel corner is the multinomial about the first saturation function; Described second trailing wheel corner is the multinomial about the second saturation function; Described compensation yaw moment is the multinomial about symbolic function; Wherein, described first saturation function and described second saturation function are specially the saturation function about the first sliding-mode surface integral operator, and described symbolic function is specially the saturation function about the second sliding-mode surface integral operator.

According to description above, above-mentioned electronlmobil stabilitrak is used for realizing above-mentioned electronlmobil stability control method, so the working process of this system is consistent with one or more embodiments of said method, has just repeated no longer one by one at this.

Those skilled in the art should understand, embodiments of the invention can be provided as method, system or computer program.Therefore, the present invention can adopt the form of complete hardware embodiment, completely software implementation or the embodiment in conjunction with software and hardware aspect.And the present invention can adopt in one or more form wherein including the upper computer program implemented of computer-usable storage medium (including but not limited to disc storage, CD-ROM, optical memory etc.) of computer usable program code.

The present invention describes with reference to according to the diagram of circuit of the method for the embodiment of the present invention, equipment (system) and computer program and/or block scheme.Should understand can by the combination of the flow process in each flow process in computer program instructions realization flow figure and/or block scheme and/or square frame and diagram of circuit and/or block scheme and/or square frame.These computer program instructions can being provided to the treater of general computer, single-purpose computer, Embedded Processor or other programmable data processing device to produce a machine, making the instruction performed by the treater of computing machine or other programmable data processing device produce device for realizing the function of specifying in diagram of circuit flow process or multiple flow process and/or block scheme square frame or multiple square frame.

These computer program instructions also can be stored in can in the computer-readable memory that works in a specific way of vectoring computer or other programmable data processing device, the instruction making to be stored in this computer-readable memory produces the manufacture comprising command device, and this command device realizes the function of specifying in diagram of circuit flow process or multiple flow process and/or block scheme square frame or multiple square frame.

These computer program instructions also can be loaded in computing machine or other programmable data processing device, make on computing machine or other programmable devices, to perform sequence of operations step to produce computer implemented process, thus the instruction performed on computing machine or other programmable devices is provided for the step realizing the function of specifying in diagram of circuit flow process or multiple flow process and/or block scheme square frame or multiple square frame.

Although describe the preferred embodiments of the present invention, those skilled in the art once obtain the basic creative concept of cicada, then can make other change and amendment to these embodiments.So claims are intended to be interpreted as comprising preferred embodiment and falling into all changes and the amendment of the scope of the invention.

Obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.

Claims (10)

1. a four motorized wheels electronlmobil stability control method, is characterized in that, described method comprises step:

S1, when four-wheel independent steering electronlmobil in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described electronlmobil; Wherein, the described speed of a motor vehicle is variable velocity;

S2, based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtain the variable ratio between the bearing circle of described electronlmobil under the different speed of a motor vehicle and trailing wheel corner;

S3, based on described steering wheel angle, obtain the front wheel angle of described electronlmobil;

S4, based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtain the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition;

S5, acquisition described vehicle-state error after, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation; When described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

2. electronlmobil stability control method as claimed in claim 1, it is characterized in that, described active rear steer controller is by linear sliding mode control module structure; Described direct yaw moment control device is by nonlinear sliding mode control module structure.

3. electronlmobil stability control method as claimed in claim 2, it is characterized in that, described variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, and described step S4 comprises the following steps:

S41, obtain the adhesion value of described electronlmobil institute track;

S42, based on described variable ratio two degrees of freedom vehicle dynamic model, described adhesion value, the described speed of a motor vehicle and described front wheel angle, obtain the expectation yaw velocity of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the actual yaw velocity of described electronlmobil is obtained; And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

4. electronlmobil stability control method as claimed in claim 3, it is characterized in that, described step S5, comprises step:

S51, based on described adhesion value, determine that described electronlmobil is operated in linearity region or nonlinear area;

S52, when described vehicle operation is in linearity region, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the first trailing wheel corner of described electronlmobil; And based on described front wheel angle, described first trailing wheel corner and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described yaw-rate error, to make described electronlmobil smooth operation;

When described vehicle operation is at nonlinear area, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the second trailing wheel corner of described electronlmobil; Meanwhile, by described direct yaw moment control device, obtain the wheel tyre power of described electronlmobil, and produce compensation yaw moment based on described wheel tyre power; And based on described front wheel angle, described second trailing wheel corner, described compensation yaw moment and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

5. electronlmobil stability control method as claimed in claim 4, it is characterized in that, described first trailing wheel corner is the multinomial about the first saturation function; Described second trailing wheel corner is the multinomial about the second saturation function; Described compensation yaw moment is the multinomial about symbolic function; Wherein, described first saturation function and described second saturation function are specially the saturation function about the first sliding-mode surface integral operator, and described symbolic function is specially the saturation function about the second sliding-mode surface integral operator.

6. a four motorized wheels electronlmobil stabilitrak, is characterized in that, described system comprises step:

Steering wheel angle and speed of a motor vehicle acquiring unit, for when four-wheel independent steering electronlmobil in running order and when needing to turn to, obtain steering wheel angle and the speed of a motor vehicle of described electronlmobil; Wherein, the described speed of a motor vehicle is variable velocity;

Variable ratio acquiring unit, for based on the described speed of a motor vehicle and speed of a motor vehicle transmitting ratio math modeling, obtains the variable ratio between the bearing circle of described electronlmobil under the different speed of a motor vehicle and trailing wheel corner;

Front wheel angle acquiring unit, for based on described steering wheel angle, obtains the front wheel angle of described electronlmobil;

Vehicle-state acquiring unit, for based on variable ratio vehicle ideal model, the described speed of a motor vehicle and described front wheel angle, obtains the vehicle perfect condition of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the vehicle existing condition of described electronlmobil is obtained; And then obtain the vehicle-state error of described vehicle existing condition relative to described vehicle perfect condition;

Stability control unit, for after the described vehicle-state error of acquisition, when described electronlmobil is operated in nonlinear area, by active rear steer controller and the direct yaw moment control device of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation; When described electronlmobil is operated in linearity region, by described active rear steer controller, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

7. electronlmobil stabilitrak as claimed in claim 6, it is characterized in that, described active rear steer controller is by linear sliding mode control module structure; Described direct yaw moment control device is by nonlinear sliding mode control module structure.

8. electronlmobil stabilitrak as claimed in claim 7, it is characterized in that, described variable ratio vehicle ideal model is specially variable ratio two degrees of freedom vehicle dynamic model, and described vehicle-state acquiring unit, comprising:

Coefficient of road adhesion acquisition module, for obtaining the adhesion value of described electronlmobil institute track;

Vehicle-state acquisition module, for based on described variable ratio two degrees of freedom vehicle dynamic model, described adhesion value, the described speed of a motor vehicle and described front wheel angle, obtains the expectation yaw velocity of described electronlmobil; Meanwhile, based on electronlmobil non-linear eight degrees of freedom model, the described speed of a motor vehicle and described front wheel angle, the actual yaw velocity of described electronlmobil is obtained; And then obtain the yaw-rate error of described actual yaw velocity relative to described expectation yaw velocity.

9. electronlmobil stabilitrak as claimed in claim 8, it is characterized in that, described stability control unit, comprising:

Work area determination module, for based on described adhesion value, determines that described electronlmobil is operated in linearity region or nonlinear area;

Stability control module, for when described vehicle operation is in linearity region, by described active rear steer controller, controls the rear wheel of described electronlmobil, obtains the first trailing wheel corner of described electronlmobil; And based on described front wheel angle, described first trailing wheel corner and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described yaw-rate error, to make described electronlmobil smooth operation;

When described vehicle operation is at nonlinear area, by described active rear steer controller, control the rear wheel of described electronlmobil, obtain the second trailing wheel corner of described electronlmobil; Meanwhile, by described direct yaw moment control device, obtain the wheel tyre power of described electronlmobil, and produce compensation yaw moment based on described wheel tyre power; And based on described front wheel angle, described second trailing wheel corner, described compensation yaw moment and the non-linear eight degrees of freedom model of described electronlmobil, control eliminate or reduce described vehicle-state error, to make described electronlmobil smooth operation.

10. electronlmobil stabilitrak as claimed in claim 9, it is characterized in that, described first trailing wheel corner is the multinomial about the first saturation function; Described second trailing wheel corner is the multinomial about the second saturation function; Described compensation yaw moment is the multinomial about symbolic function; Wherein, described first saturation function and described second saturation function are specially the saturation function about the first sliding-mode surface integral operator, and described symbolic function is specially the saturation function about the second sliding-mode surface integral operator.