阅读说明：本技术 机动车辆转向控制系统及转向控制方法 (Motor vehicle steering control system and steering control method ) 是由 陈柏全 李旻贞 陈韦仲 林育民 陈元骏 顾迪 于 2018-06-07 设计创作，主要内容包括：一种机动车辆转向控制系统,用以执行一转向控制方法,以对一机动车辆的转向轮进行转向。转向控制方法包含：接收一转向参考角度以及一实际转向角度,依据转向参考角度及实际转向角度计算一控制力矩；依据实际转向角度及转向参考角度于一取样时间内的变化,而得到一实际转向角速度以及一转向参考角速度,并依据实际转向角速度以及转向参考角速度,以得到一摩擦力矩补偿；估测转向后产生的一回正力矩估测；以及依据控制力矩、摩擦力矩补偿以及回正力矩估测计算辅助力矩,输出辅助力矩。(A motor vehicle steering control system is used for executing a steering control method to steer the steering wheel of a motor vehicle. The steering control method includes: receiving a steering reference angle and an actual steering angle, and calculating a control moment according to the steering reference angle and the actual steering angle; obtaining an actual steering angular velocity and a steering reference angular velocity according to the change of the actual steering angle and the steering reference angle in a sampling time, and obtaining a friction torque compensation according to the actual steering angular velocity and the steering reference angular velocity; estimating a correcting moment generated after steering; and estimating and calculating the auxiliary torque according to the control torque, the friction torque compensation and the aligning torque, and outputting the auxiliary torque.)

1. A motor vehicle steering control system for steering a steerable wheel of a motor vehicle, comprising:

The electric auxiliary steering module is used for outputting an auxiliary torque to the steering wheel;

The motor driving circuit is used for receiving a control command and outputting a motor driving current according to the control command so as to drive the electric auxiliary steering module to output the auxiliary torque;

An angle sensor for detecting an actual steering angle; and

a controller for generating the control command, wherein

The controller receives a steering reference angle and calculates a control moment according to the steering reference angle and the actual steering angle;

The controller obtains an actual steering angular velocity and a steering reference angular velocity according to the change of the actual steering angle and the steering reference angle in a sampling time, and obtains a friction torque compensation according to the actual steering angular velocity and the steering reference angular velocity;

the controller estimates a aligning moment estimation generated by aligning the steering wheel after steering; and

The controller calculates the auxiliary torque according to the control torque, the friction torque compensation and the aligning torque estimation, and generates the control command.

2. A motor vehicle steering control system according to claim 1, further comprising:

and the torque sensor is connected with the electric auxiliary steering module and used for detecting the driving torque input by a driver so that the controller can judge the steering intention of the driver.

3. The motor vehicle steering control system according to claim 1 or 2, further comprising:

And the current sensor is connected with the motor driving circuit and used for detecting the motor driving current and feeding back the motor driving current to the controller.

4. The motor vehicle steering control system according to claim 1,

The controller calculates a steering angle difference according to the steering reference angle and the actual steering angle, and multiplies the steering angle difference by a transfer function to obtain the control torque.

5. the motor vehicle steering control system according to claim 1,

The controller compares whether the absolute value of the actual steering angular velocity is greater than a first threshold value, and if the absolute value of the actual steering angular velocity is greater than the first threshold value, the controller calculates the friction torque compensation according to the actual steering angular velocity;

If the absolute value of the actual steering angular velocity is not greater than the first threshold value, the controller compares whether the absolute value of the steering reference angular velocity is greater than a second threshold value; if the absolute value of the steering reference angular speed is larger than the second threshold value, the controller calculates the friction torque compensation according to the steering reference angular speed; and if the absolute value of the actual steering angular velocity is not greater than the first threshold value and the absolute value of the steering reference angular velocity is not greater than the second threshold value, the controller sets the friction torque compensation to zero.

6. the system of claim 1, wherein the controller obtains the aligning torque estimate through a Kalman filter with an estimated gain matrix.

7. A steering control method for steering a steered wheel of a motor vehicle, comprising:

Receiving a steering reference angle and an actual steering angle, and calculating a control moment according to the steering reference angle and the actual steering angle;

Obtaining an actual steering angular velocity and a steering reference angular velocity according to the change of the actual steering angle and the steering reference angle in a sampling time, and obtaining a friction torque compensation according to the actual steering angular velocity and the steering reference angular velocity;

estimating a correcting moment generated after steering; and

And calculating an auxiliary torque according to the control torque, the friction torque compensation and the aligning torque estimation, and outputting the auxiliary torque.

8. The steering control method according to claim 7, further comprising:

The driving torque input by a driver is detected so that the controller can judge the steering intention of the driver.

9. The steering control method according to claim 7, wherein the step of calculating the control torque includes:

And calculating a steering angle difference according to the steering reference angle and the actual steering angle, and multiplying the steering angle difference by a transfer function to obtain the control torque.

10. The steering control method according to claim 7, wherein the step of calculating the friction torque compensation includes:

Comparing whether the absolute value of the actual steering angular velocity is greater than a first threshold value, and if the absolute value of the actual steering angular velocity is greater than the first threshold value, calculating the friction torque compensation according to the actual steering angular velocity;

If the absolute value of the actual steering angular velocity is not greater than the first threshold value, comparing whether the absolute value of the steering reference angular velocity is greater than a second threshold value; if the absolute value of the steering reference angular speed is larger than the second threshold value, calculating the friction torque compensation according to the steering reference angular speed; and

If the absolute value of the actual steering angular velocity is not greater than the first threshold value and the absolute value of the steering reference angular velocity is not greater than the second threshold value, the friction torque compensation is set to zero.

Technical Field

The present invention relates to an electric power assisted steering module for steering a motor vehicle, and more particularly, to a steering control system and a steering control method for a motor vehicle.

Background

As the weight and speed of the motor vehicle increases, the steering torque required to steer the motor vehicle exceeds the control torque available from human power, and additional torque assistance is required from the auxiliary steering system. An existing Electric Power Steering (EPS) system can provide a more precise Steering torque and Steering angle, and is easy to establish connection with a driving computer for the driving computer to intervene for dynamic control of the motor vehicle, such as assisting in lane keeping.

In order to provide accurate assist torque, a correct disturbance evaluation is required to provide sufficient assist torque, too small assist torque cannot timely meet the requirement of control torque, and the steering angular velocity generated by too large assist torque affects the stability of the vehicle body. However, various disturbances are considered in the calculation of the auxiliary torque, so that the related influence of the disturbance input on the control result is eliminated, and the effective disturbance input elimination is achieved to accurately control the running of the vehicle.

Disclosure of Invention

In view of the above problems, the present invention provides a steering control system and a steering control method for a motor vehicle, which provide more accurate assist torque by estimating external disturbance of control torque.

In order to achieve the above object, the present invention provides a motor vehicle steering control system for steering a steered wheel of a motor vehicle, comprising an electric auxiliary steering module, a motor driving circuit, an angle sensor and a controller. The electric auxiliary steering module is used for outputting an auxiliary torque to the steering wheel. The motor driving circuit is used for receiving a control command and outputting a corresponding motor driving current according to the control command so as to drive the electric auxiliary steering module to output the auxiliary torque. The angle sensor is used for detecting an actual steering angle. The controller is used for generating a control command. The controller receives a steering reference angle and calculates a control moment according to the steering reference angle and an actual steering angle; the controller obtains an actual steering angular velocity and a steering reference angular velocity according to the change of the actual steering angle and the steering reference angle in a sampling time, and obtains a friction torque compensation according to the actual steering angular velocity and the steering reference angular velocity; the controller estimates a correction torque estimation generated by the steering wheel after steering; and the controller calculates the auxiliary torque according to the control torque, the friction torque compensation and the aligning torque estimation to generate a control command.

The present invention also provides a steering control method for steering a steered wheel of a motor vehicle, comprising: receiving a steering reference angle and an actual steering angle, and calculating a control moment according to the steering reference angle and the actual steering angle; obtaining an actual steering angular velocity and a steering reference angular velocity according to the change of the actual steering angle and the steering reference angle in a sampling time, and obtaining a friction torque compensation according to the actual steering angular velocity and the steering reference angular velocity; estimating a correcting moment generated after steering; and estimating and calculating an auxiliary torque according to the control torque, the friction torque compensation and the aligning torque, and outputting the auxiliary torque.

The invention uses the sensor to directly detect the change of the electric auxiliary steering module, obtains all necessary parameters to calculate the auxiliary torque, and ensures that the calculated result has better reliability.

Drawings

FIG. 1 is a block diagram of a system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an information flow in the embodiment of the present invention.

FIG. 3 is a flow chart of a method according to an embodiment of the present invention.

Fig. 4 is a detailed flowchart of Step 120 in fig. 3.

FIG. 5 is a diagram illustrating disturbance estimation for estimating aligning torque in FIG. 3.

FIG. 6 is a block diagram of a feedback control architecture according to an embodiment of the present invention.

Fig. 7, 8 and 9 are schematic diagrams of different specific application examples of the present invention.

Wherein the reference numerals are:

100 electric power assisted steering module (EPS module)

200 controller 300 motor driving circuit

400-degree sensor 500 torque sensor

600 current sensor V, V' motor vehicle

b obstacle

θ_refSteering reference angle theta_mActual steering angle

T_aAligning momentEstimated value of aligning moment

T_mAuxiliary torque T_cControl moment

c transfer functionFriction torque compensation

Estimated Coulomb friction torque Delta theta_mActual steering angular velocity

Δθ_refSteering reference angular velocity L_pEstimating a gain matrix

ε₁First threshold value epsilon 2 and second threshold value

Detailed Description

Referring to fig. 1, a motor vehicle steering control system for implementing a steering control method to steer a steered wheel of a motor vehicle V according to an embodiment of the present invention is disclosed. The steering control system of a motor vehicle comprises an electric power assisted steering module 100

An Electric Power Steering Module (EPS), a controller 200, a motor driving circuit 300, an angle sensor 400, a torque sensor 500 and a current sensor 600.

As shown in fig. 1, the EPS module 100 includes a steering column and an auxiliary motor. The steering column is connected to the steering wheel, to the V-steering wheel of the motor vehicle and to the auxiliary motor for providing an auxiliary torque T in addition to the driving torque applied by the driver to the steering column_mSo that the steering column provides sufficient steering torque to the steered wheels of the motor vehicle V. The EPS module 100 is a well-developed technology in the field of motor vehicle engineering, and its basic components and operation principles are generally known to be implemented according to the prior art, so that the technical details thereof will not be described in detail below. The motor driving circuit 300 is connected to the EPS module 100, and is configured to output a corresponding motor driving current according to a control command of the controller 200 to drive the EPS module 100 to output a corresponding assist torque T_m。

the rotational dynamics of the steering column can be expressed by the rotational dynamics equation as follows:

Wherein the content of the first and second substances,

I is the moment of inertia of the steering column;

Is the steering column angular acceleration;

T_dis the driving torque (steering torque provided by the driver);

T_mis the assist torque applied by the assist motor to the steering column;

T_fis the friction torque inside the steering column;

T_aIs a aligning moment generated by aligning the steered wheels after steering.

The above-mentioned friction torque T_fMainly related to the angular velocity ω, and can be expressed as the equation T of the angular velocity ω_f(ω)。T_f(ω) can be simulated by LuGre static friction model, which can be divided into four main friction effects such as Coulomb friction, viscous friction, Stribeck effect and dynamic friction, and when the angular velocity ω is zero, the friction torque is zero, so T_f(ω) can be expressed as:

Wherein the content of the first and second substances,

α₀Is the coulomb friction torque coefficient;

α₁is the static friction moment coefficient;

α₂Is a viscous friction coefficient;

ω_sIs the Striebeck speed.

Alpha as defined above₀、α₂the measurement can be obtained by a systematic measurement, such as the least squares method (l.ljung, "System Identification," Signal analysis and prediction) provided in the known literature.Boston,pp.163-173,1998.)；α₁、ω_sReference may be made to the values provided in the known literature (e.g. S.S.Ge, T.H.Lee, and S.X.ren, "Adaptive front compensation of ser vo mechanisms," int.J.Syst. Sci., vol.32, No.4, pp.523-532, Jan.2001.).

The LuGre static friction model loading system of the above equation (2) is further simplified when it is active, and the static friction force is ignored, so as to facilitate the system discrimination:

T_f(ω)＝T_f,c+T_f,b＝α₀sgn(ω)+α₂ω (3)

Wherein the content of the first and second substances,

T_f,ccoulomb friction torque;

T_f,bit is a viscous friction torque.

After the simplified LuGre static friction model equation (3) is substituted into the rotational dynamic equation (1), the rotational dynamic equation (1) can be simplified into equation (4).

As described aboveThe steering moment required for enabling the steering wheel to generate steering in the preset direction is obtained; t is_mAnd T_dAn assist torque provided for the EPS module 100 and a driving torque generated by the driver rotating the steering wheel, respectively; the rest is friction torque and aligning torque T_aEqual disturbance, need to adjust the auxiliary torque T_mTo compensate.

Equation (4) can be simplified from equation (3) as follows:

T_f,cCompensation is the coulomb friction torque inside the EPS module 100, which is also the friction torque to be estimated; alpha is alpha₂Is the viscous friction coefficient and is also the rotational damping coefficient inside the EPS module 100;Is the steering column angular velocity (i.e., ω).

Wherein the friction torque is compensated for T_f,cwith steering angle delta theta per unit time_mDifference (A)I.e. angular velocity ω), friction torque compensation T_f,cCan pass through Coulomb friction torque alpha₀multiplied by the angular velocity ω.

The above equation (5) can be expressed as a spatial matrix:

Wherein the content of the first and second substances,including steering angle theta, angular velocity omega and aligning moment T_a. In the case of active steering, the driving torque T_dzero, the system input u ═ T_m-T_f,cDeducting the estimated coulomb friction torque for the motor torque; w is the interference noise of the system; alpha is alpha₂Is the rotational damping coefficient of the steering system; i is the moment of inertia of the steering system, and the state matrix, control input matrix, and disturbance input matrix of the steering system, the details of each matrix are shown in equation (7).

the state system of equations (6) and (7) converted to discrete time is:

x(k+1)＝Φx(k)+Гu(k)+Г₁w(k)

y(k)＝Hx(k)-υ(k) (8)

Where y (k) is x (k) is the output of the discrete time transfer function H, w (k) is the interference noise of the system, v (k) is the perceptron measurement error, and these two random sequences are both zero mean values, as shown in equation (9):

ε{w(k)}＝ε{v(k)}＝0 (9)

The above equation is used to estimate the state term through a Kalman Filter (Kalman Filter), as shown in equation (10). And cooperate with the sensor measurement value y (k) and the estimated gain matrix L_pUpdating the estimate, as in equation (11), to obtain the best estimate

WhereinIn order to estimate the state of the system,in order to be able to estimate the direction of turning,in order to estimate the angular velocity of the steering wheel,is an estimate of the aligning moment. In equation (10), fromToThe process of (c) may be referred to as time updating, in which the covariance matrix p (k) is estimated, as shown in equation (12). And in the case of the equation (11),Tothe process of (2) is called measurement update, in which the gain matrix L is estimated_pThe update is performed based on the estimated covariance matrix P, as shown in equation (13). M is the covariance matrix updated from the P measurements, as in equation (14). And in the equations (12), (13), (14), R_vIs the system sensor weight, R_wThen the actual interference weight.

P(k)＝M(k)-M(k)H^T(HM(k)H^T+R_v)^-1HM(k) (12)

L_P(k)＝P(k)^TR_V ^-1 (13)

Referring to fig. 1 and 2, first, a steering reference angle θ is generated according to driving operation, driving dynamics monitoring, dynamic stability system of driving computer or other auxiliary operation mechanism_refand is input to the controller 200 as an angle requirement.

Controller 200 according to steering reference angle theta_refCalculating a control moment T applied to a steering wheel_c. The steering reference angle theta_refThe steering angle that needs to be output by the EPS module 100 is calculated according to different requirements such as turning, lateral movement to change lanes, or lateral movement to stabilize the vehicle body to maintain in the lane.

The angle sensor 400 is connected to the EPS module 100 and is used for continuously measuring the current actual steering angle θ of the EPS module 100_mAnd transmitted to the controller 200.

As shown in fig. 1, 2, and 3, the controller 200 may calculate a steering reference angle θ_refand the actual steering angle theta_mTo obtain a steering angle difference (Δ θ ═ θ)_ref-θ_m) I.e., how many degrees the EPS module 100 also needs to steer the steered wheel. Controller 200 simultaneously uses the steering angle difference (Δ θ ═ θ)_ref-θ_m) Calculating the control torque T that the EPS module 100 needs to provide to the steered wheels_cAs shown in Step 110. Control moment T_cThe magnitude of (b) can be obtained by a transfer function C, and the controller 200 multiplies the steering angle difference by the transfer function C to obtain the control torque T_CThe manner in which the transfer function C is obtained is described below.

First, the controller 200 is designed by an IMC controller (Internal Model Control) so that the Control torque estimation shown in FIG. 6 can form an actual Model G and an approximate ModelConnected in parallel, in feedback connection to the IMC controller G_imcThe structure of (1), as in document B.A.Francis and W.M.Wonnham, "TThe design principle proposed by he internal model of control theory, "Automatica, vol.12, No.5, pp.457-465,1976. Based on the foregoing architecture and design principles, a transfer function C can be obtained as:

According to equation (15), the steering angle difference (Δ θ ═ θ) can be determined_ref-θ_m) Calculating a control moment T_C：

Tc＝(θ_ref-θ_m)×C (16)

As shown in fig. 1 and 2, the torque sensor 500 is connected to the EPS module 100 for detecting the driving torque T input by the driver through the steering wheel_dand then transmitted to the controller 200 for the controller 200 to determine the steering intention of the driver.

Referring to fig. 1, 2 and 3, the controller 200 calculates the friction torque compensationas shown in Step 120.

Friction torque compensationas shown in fig. 4, first, the controller 200 continuously receives the actual steering angle θ_mCalculating an actual steering angle theta_mVariation delta theta in a sampling time_mAnd the actual steering angle change Δ θ during this sampling time_mCan be regarded as the actual steering angular velocityController 200 compares actual steering angular velocity Δ θ_mIs greater than a first threshold value epsilon₁as shown in Step 121.

if the change Δ θ in the actual sampling time is equal to Step122_mIs greater than a first threshold value epsilon₁Represents the actual result of the angle sensor 400Change in steering angle Δ θ_mNot of noise, so that the friction torque compensates for T_f,cWith actual steering angular velocity delta theta_mhas higher degree of correlation. At this time, the controller 200 controls the actual steering angular velocity Δ θ_mcalculating an estimate of friction torque compensationAnd at the actual steering angular velocity delta theta_mDetermining an estimated value of friction torque compensationIn the direction of (a):

The above equation, the function symbol sgn is used to representDirectivity of (1) and actual steering angular velocity delta theta_mIn the context of the association of (a) to (b),for the estimated coulomb friction torque, the complete equation before simplification is referred to equation (2).

As shown in Step123, if the actual steering angular velocity Δ θ_mIs less than or equal to, i.e. the actual steering angular velocity delta theta_mIs not greater than a first threshold value epsilon₁The controller 200 will then determine the actual steering angular velocity Δ θ_mit is considered as noise, i.e., there is no actual steering angular velocity. At this time, the steering reference angle theta needs to be judged_refamount of change Δ θ of_ref. The controller 200 calculates a steering reference angle theta at a sampling time_refAmount of change Δ θ of_refTo serve as a steering reference angular velocity, and further comparing the steering reference angular velocity Δ θ_refIs greater than a second threshold value epsilon₂。

If the steering reference angular velocity Δ θ is determined in Step 124_refToFor values greater than a second threshold value epsilon₂representing an estimate of friction torque compensation by the EPS module 100 steering the intervening steering columnand steering reference angular velocity delta theta_refHas higher degree of correlation. At this time, the controller 200 turns to the reference angular velocity Δ θ_refcalculating a friction torque compensation estimateAnd at a steering reference angular velocity delta theta_refpositive and negative value determination friction torque compensation estimation valueIn the direction of (a).

the above equation, the function symbol sgn is used to representDirectivity of (1) and actual steering angular velocity delta theta_refIn the context of the association of (a) to (b),For the estimated coulomb friction torque, the complete equation before simplification is referred to equation (2).

If the steering reference angular velocity Δ θ is determined as shown in Step 125_refIs also not greater than the second threshold value epsilon₂if the friction torque compensation is not performed, it means that the motor vehicle V itself has no need for changing the steering, i.e. the EPS module 100 does not drive the steering column to rotate and does not generate the rotational friction, so the controller 200 estimates the friction torque compensation valueIs set to zero.

In fact, the first threshold value ε₁And a firstTwo threshold values epsilon₂Are threshold values for filtering noise, the magnitude of which may be determined by the sensitivity of angle sensor 400. For example, when the sensitivity of the angle change rate (i.e., the angular velocity) detected by the angle sensor 400 is 0.1 degree/second, the condition that the angle change amount is less than 0.2 degrees per unit time can be set as noise, i.e., the steering column in the EPS module 100 has no angle change and does not need friction torque compensation, and the controller 200 sets the estimated value of friction torque compensationIs zero.

as shown in fig. 1, 2 and 3, the controller 200 then estimates the aligning torque T_aAs shown in Step 130.

Referring to FIG. 5, as mentioned above, the rotational dynamics of the steering column can be expressed by the equation for the rotational dynamics:

After the above-mentioned rotational dynamic equation is spatially matrixed by equation (6), the estimation gain matrix L is matched by Kalman Filter (Kalman Filter)_plet L_pover time, by varying L_pTo estimate the disturbance in order to obtain the actual steering angular velocity(i.e. omega), the assistance torque T estimated at the previous point in time_mAnd the current friction torque compensation T_f,cto estimate the gain matrix L_piterate by L_pOver time, by varying L_pTo estimate the disturbance to obtain the estimated values of aligning torque at different times

Referring to fig. 1, 2 and 3, finally, the controller 200 can calculate the current assist torqueAs shown in Step 140.

Finally, the controller 200 issues a control command to control the motor driving circuit 300 to output a corresponding motor driving current to drive the auxiliary motor in the EPS module 100, so that the EPS module 100 outputs an auxiliary torque T_mThereby controlling the steering angle of the steering wheel through the driving of the steering column.

As shown in fig. 1 and fig. 2, the current sensor 600 is connected to the motor driving circuit 300 for detecting the magnitude of the motor driving current, and feeding the detected magnitude back to the controller 200, so that the controller 200 can determine and adjust the assist torque T output by the EPS module 100_m。

The aforementioned assist torque T_mIt is assumed that driving without steering intent provides no driving torque. In fact, the driving torque detected by the torque sensor 500 is continuously fed back to the controller 200 to adjust the auxiliary torque T actually required to be output_m。

Referring to FIGS. 1 and 6, the actual feedback structure is at the steering reference angle θ_refAfter being input to the controller 200 as an angle demand, the controller 200 continuously receives the actual steering angle θ_mAnd according to the actual steering angle theta_mCalculating an estimated value of control torqueFriction moment compensation estimation valueand disturbance estimation (estimation of aligning moment)) And re-iterating the control torque estimateFriction moment compensation T_f,cand estimating aligning torqueIn which the actual aligning moment T is further used_aAnd judging the estimation error.

As shown in fig. 1 and 7, in an embodiment of the present invention, a driving computer of a motor vehicle V can identify whether the motor vehicle V deviates from a lane by recognizing a road mark or other recognition means through an image. The driving computer outputs a steering reference angle theta required by lane driving according to the identification and analysis of the lane maintaining system_refTo correct the direction of travel of the motor vehicle V. At this time, according to the steering reference angle θ_refThe controller 200 starts to receive the parameters from the angle sensor 400, the torque sensor 500 and the current sensor 600 and continuously calculates the estimated control torque valueFriction moment compensation estimation valueestimating aligning torqueTo obtain an assist torque T_mAnd the driving motor circuit outputs corresponding current to drive the EPS module 100 to output the assist torque T_m. The controller 200 continuously receives feedback of various parameters and continuously corrects the auxiliary torque T_mSteering angle control while maintaining the motor vehicle V on the lane.

as shown in fig. 1 and 8, in another embodiment of the present invention, the driving computer of the vehicle V can identify other vehicles V' with relatively low speed in front of the vehicle V by image recognition of road markings or other recognition means, and then return to the original lane after passing through the lane. At the moment, the driving computer firstly predicts the changing driving track and continuously outputs the steering reference angle theta_refThe motor vehicle V is moved according to the trajectory. At this time, according to the steering reference angle θ_refThe controller 200 starts to receive parameters and continuously calculates the estimated value of the control torqueFriction moment compensation estimation valueestimating aligning torqueTo obtain an assist torque T_mAnd the driving motor circuit outputs corresponding current to drive the EPS module 100 to output the assist torque T_m. The controller 200 continuously receives feedback of various parameters and continuously corrects the auxiliary torque T_mAnd steering angle control to move the motor vehicle V according to the trajectory. At this time, if the driving torque is detected, the assist torque T is corrected according to the driving torque_mFor example to reduce the assistance torque T_mTo output of (c). Or, the current over-steering or under-steering caused by the driving moment assists to correct the actual steering angle theta_mmake it conform to the steering reference angle theta_ref。

As shown in fig. 1 and 9, in another embodiment of the present invention, a driving computer of a motor vehicle V can identify an obstacle B, such as a pedestrian, in front of the motor vehicle V by image recognition of a road marking or other recognition means, and make a decision to change lane evasion; or, the running computer is reported by the controller 200 to suddenly and rapidly increase the actual steering angle theta_mAnd judging that lane change evasion is required to be carried out during driving. At the moment, the driving computer firstly predicts the changing driving track and continuously outputs the steering reference angle theta_refThe motor vehicle V is moved according to the trajectory. At this time, according to the steering reference angle θ_refthe controller 200 starts to receive the parameters from the angle sensor 400, the torque sensor 500 and the current sensor 600 to obtain the auxiliary torque T_mAnd the driving motor circuit outputs corresponding current to drive the EPS module 100 to output the assist torque T_mAnd continuously corrects the assist torque T_mand steering angle control. At this time, if the driving torque T is detected_dJudging whether understeer or oversteer is performed or not, and using the assist torque T_minterventional assisted correction of actual steering angle θ_mAnd actual steering angular velocity Δ θ_m(change of angle in sampling time) to conform to steering reference angle theta_refand steering reference angular velocity Δ θ_refSo as to avoid the situation that the driving operation can not avoid the obstacle or the vehicle is turned over due to over steering.

The invention uses a sensor to directly detect the change of the EPS module 100, and obtains each necessary parameter to calculate the auxiliary torque T_mthe uncertainty of the obtained parameters is reduced, so that the calculated result is effective and good in reliability.

If the absolute value of the actual steering angular velocity is not greater than the first threshold value, the controller compares whether the absolute value of the steering reference angular velocity is greater than a second threshold value; if the absolute value of the steering reference angular speed is larger than the second threshold value, the controller calculates the friction torque compensation according to the steering reference angular speed; and

if the absolute value of the actual steering angular velocity is not greater than the first threshold value and the absolute value of the steering reference angular velocity is not greater than the second threshold value, the controller sets the friction torque compensation to zero.

6. The system of claim 1, wherein the controller obtains the aligning torque estimate through a Kalman filter with an estimated gain matrix.

7. a steering control method for steering a steered wheel of a motor vehicle, comprising:

Receiving a steering reference angle and an actual steering angle, and calculating a control moment according to the steering reference angle and the actual steering angle;

Obtaining an actual steering angular velocity and a steering reference angular velocity according to the change of the actual steering angle and the steering reference angle in a sampling time, and obtaining a friction torque compensation according to the actual steering angular velocity and the steering reference angular velocity;

Estimating a correcting moment generated after steering; and

And calculating an auxiliary torque according to the control torque, the friction torque compensation and the aligning torque estimation, and outputting the auxiliary torque.

8. The steering control method according to claim 7, further comprising:

The driving torque input by a driver is detected so that the controller can judge the steering intention of the driver.

9. The steering control method according to claim 7, wherein the step of calculating the control torque includes:

And calculating a steering angle difference according to the steering reference angle and the actual steering angle, and multiplying the steering angle difference by a transfer function to obtain the control torque.

10. The steering control method according to claim 7, wherein the step of calculating the friction torque compensation includes:

Comparing whether the absolute value of the actual steering angular velocity is greater than a first threshold value, and if the absolute value of the actual steering angular velocity is greater than the first threshold value, calculating the friction torque compensation according to the actual steering angular velocity;

If the absolute value of the actual steering angular velocity is not greater than the first threshold value, comparing whether the absolute value of the steering reference angular velocity is greater than a second threshold value; if the absolute value of the steering reference angular speed is larger than the second threshold value, calculating the friction torque compensation according to the steering reference angular speed; and

If the absolute value of the actual steering angular velocity is not greater than the first threshold value and the absolute value of the steering reference angular velocity is not greater than the second threshold value, the friction torque compensation is set to zero.