CN101934815A - Electric power-assisted steering system with active correction control function - Google Patents

Abstract

The invention relates to an electric power-assisted steering system with active correction control function, which comprises a torque sensor, a steering wheel corner sensor, a vehicle speed sensor, an electronic control unit, a steering power-assisted motor and a speed reducer thereof, which are additionally arranged in the traditional mechanical steering system. The electric power-assisted steering system with active correction control function combines a corner signal of a steering wheel, a torque signal of the torque sensor and a vehicle speed signal of the vehicle speed sensor together to be input into an active correction control module of the electronic control unit and judges whether the steering wheel is in a correction state or not; and if the steering wheel is in the correction state, proper correction control torque is calculated and corresponding torque is output by the motor. The invention carries out correction control by using the corner signal, the torque signal and the vehicle speed signal, is suitable for electric power-assisted steering systems in various power-assisted modes, and improves the correction property of the vehicle without influencing the control hand feel of a driver.

Description

Has the initiatively electric boosting steering system of aligning control function

Technical field

The invention belongs to automobile technical field, relate to electric boosting steering system, especially a kind of electric boosting steering system (Electric Power Steering System is called for short EPS) with active aligning control function.

Background technology

Electric boosting steering system comprises the mechanical steering system, torque sensor, and steering wheel angle sensor, car speed sensor, electronic control unit, power steering motor and speed reduction gearing thereof are formed.Wherein, described torque sensor is installed on the steering shaft of described mechanical steering system to detect pilot control moment and output torque signal; Car speed sensor is used to detect the moving velocity of present vehicle and exports vehicle speed signal; Steering wheel angle sensor is used to detect steering handwheel off-straight traveling-position and output angle signal; The driving current value that need provide for the power steering motor is provided electronic control unit; The power steering motor can be installed in mechanical steering axle or the deflector, provides assist torque by speed reduction gearing to chaufeur.Electronic control unit comprises basic power operated control module, current of electric control module and fault diagnosis module.

Traditional electric power steering control system can improve the ease of steering of vehicle, still, when low speed driving, because the situation that steering handwheel can't be got back to midway location can appear in the influence of steering hardware friction moment, has reduced the driving safety of vehicle.

Summary of the invention

The objective of the invention is in order to improve the low speed return performance of electric boosting steering system, a kind of initiatively electric boosting steering system of aligning control function that has is provided, this system can guarantee the steering reversal performance of electric boosting steering system under low speed effectively, and can not influence the manipulation feel of chaufeur.

For reaching above purpose, the technical solution used in the present invention is:

A kind of electric boosting steering system with active aligning control function comprises the mechanical steering system, torque sensor, steering wheel angle sensor, car speed sensor, electronic control unit, power steering motor and speed reduction gearing thereof; Wherein, described torque sensor is installed on the steering shaft of described mechanical steering system to detect pilot control moment and output torque signal; Steering wheel angle sensor is used to detect steering handwheel off-straight traveling-position and output angle signal; Car speed sensor is used to detect the moving velocity of present vehicle and exports vehicle speed signal; The driving current value that need provide for the power steering motor is provided electronic control unit; The power steering motor can be installed in mechanical steering axle or the deflector, provides assist torque by speed reduction gearing to chaufeur; Described electronic control unit comprises Torque Control module, current of electric control module and fault diagnosis module; The Torque Control module is accepted torque signal, vehicle speed signal and angle signal and to current of electric control module output control signal, this Torque Control module comprises basic power operated control module, initiatively return the positive control module, damping control module, it is characterized in that, the described positive control module of initiatively returning comprises back positive judge module and aligning torque computing module, return positive judge module according to accepting torque signal, vehicle speed signal and angle signal, judge whether steering handwheel is in back positive status, if be in back positive status, the aligning torque computing module that then initiatively returns in the positive control module calculates suitable time positive control moment to the current of electric control module, and exports corresponding aligning torque by current of electric control module control power steering motor.

Owing to adopted above technical scheme, the invention has the beneficial effects as follows: by utilizing the steering wheel angle signal, torque signal, and vehicle speed signal is returned positive control, this method is applicable to the electric boosting steering system of various assist types, improve the return performance of vehicle, can not influence the manipulation feel of chaufeur simultaneously.

Description of drawings

Fig. 1 is the initiatively Torque Control module principle figure of the electric boosting steering system of aligning control function that has of the present invention.

Fig. 2 is the initiatively time positive judge module determining program diagram of circuit of the electric boosting steering system of aligning control function that has of the present invention.

Fig. 3 is that the returning with steering handwheel of electric boosting steering system with active aligning control function of the present invention is being the aligning torque method of calculating schematic diagram of the corner closed loop control of controlled target to midway location just.

Fig. 4 be the electric boosting steering system with aligning control function initiatively of the present invention just return with steering handwheel that real vehicle returns positive empirical curve under the 20km/h speed of a motor vehicle of aligning torque method of calculating of corner closed loop control that midway location is a controlled target.

Fig. 5 of the present inventionly has the desirable steering swivel system of using in the corner closed loop aligning torque method of calculating based on model following of the electric boosting steering system of aligning control function initiatively and returns positive model.

Fig. 6 of the present inventionly has the desirable steering handwheel that desirable steering swivel system that the corner closed loop aligning torque method of calculating based on model following of the electric boosting steering system of aligning control function initiatively uses returns positive model output and returns positive corner-time history.

Fig. 7 is the initiatively corner closed loop aligning torque method of calculating schematic diagram based on model following of the electric boosting steering system of aligning control function that has of the present invention.

Fig. 8 is that the real vehicle based on the corner closed loop aligning torque method of calculating of model following of the electric boosting steering system with aligning control function initiatively of the present invention returns positive empirical curve.(steering wheel angle when not having back positive control and positive control being arranged back-time history contrast)

Fig. 9 is the initiatively time positive judgment experiment checking curve of the electric boosting steering system of aligning control function that has of the present invention.

Figure 10 is that the real vehicle based on the corner closed loop aligning torque method of calculating of model following of the electric boosting steering system with aligning control function initiatively of the present invention returns positive empirical curve.(when the 10km/h and the 20km/h speed of a motor vehicle, reference model output and actual rotational angle output)

Figure 11 is the initiatively block diagram based on the control of model following fuzzy self-adaption of the electric boosting steering system of aligning control function that has of the present invention.

Figure 12 is the initiatively fuzzy self-adaption control law enquiry form based on the model following Fuzzy Adaptive Control Scheme of the electric boosting steering system of aligning control function that has of the present invention.(input/output variable is through 3 dimension question blanks of the aligning torque under certain corner after the normalization method)

Figure 13 is that the real vehicle based on the model following Fuzzy Adaptive Control Scheme with electric boosting steering system of active aligning control function of the present invention returns positive empirical curve.(steering wheel angle when not having back positive control and positive control being arranged back-time history contrast)

Figure 14 is that the real vehicle based on the model following Fuzzy Adaptive Control Scheme with electric boosting steering system of active aligning control function of the present invention returns positive empirical curve.(when the 10km/h and the 20km/h speed of a motor vehicle, reference model output and actual rotational angle output)

The specific embodiment

The present invention is further illustrated below in conjunction with the accompanying drawing illustrated embodiment.

Have the initiatively electric boosting steering system of aligning control function, comprise the mechanical steering system, torque sensor, steering wheel angle sensor, car speed sensor, electronic control unit, power steering motor and speed reduction gearing thereof are formed.Wherein, torque sensor is installed on the steering shaft of mechanical steering system to detect pilot control moment and output torque signal; Steering wheel angle sensor is used to detect the angle signal of steering handwheel off-straight traveling-position and output; Car speed sensor is used to detect the moving velocity of present vehicle and exports vehicle speed signal; The driving current value that need provide for the power steering motor is provided electronic control unit; The power steering motor can be installed in mechanical steering axle or the deflector, provides assist torque by speed reduction gearing to chaufeur.

Electronic control unit comprises Torque Control module, current of electric control module and fault diagnosis module; The Torque Control module is accepted torque signal, vehicle speed signal and angle signal and is exported control signal to the current of electric control module.

Referring to Fig. 1, this Torque Control module comprises basic power operated control module, initiatively return the positive control module, the high speed damping control module, the input end of three control modules and torque sensor, steering wheel angle sensor, car speed sensor connects, accept torque signal, vehicle speed signal and angle signal, the mouth of three control modules is connected with the current of electric control module, to current of electric control module output control signal.Initiatively return the positive control module and comprise back positive judge module and aligning torque computing module, return the input end and the torque sensor of positive judge module, steering wheel angle sensor, car speed sensor connects, accept torque signal, vehicle speed signal and angle signal, judge whether steering handwheel is in back positive status, if be in back positive status, then return positive judge module with signal feedback to the aligning torque computing module that initiatively returns in the positive control module, the aligning torque computing module calculates suitable time positive control moment, and exports corresponding aligning torque by current of electric control module control power steering motor.The present invention utilizes the steering wheel angle signal, torque signal, and vehicle speed signal returns positive control, is applicable to the electric boosting steering system of various assist types, improves the return performance of vehicle, can not influence the manipulation feel of chaufeur simultaneously.

Return positive judge module and judge according to steering wheel angle signal, bearing circle tach signal (can obtain by the steering wheel angle signal differentiation, perhaps obtain), torque sensor signal whether vehicle is in back positive status by the motor speed estimation.The design of returning positive judge module is based on the state machine theory, by just being decomposed into back, the steering reversal operation judges, return and just to await orders, return and just beginning three kinds of states, direction of passage dish angular signal, bearing circle tach signal, torque sensor signal are judged the current aligning torque that whether needs to apply again.

Concrete judgement flow process such as Fig. 2, at this moment the determining program initialization enters back and just judges state, just forbids back, if can not satisfy condition A, then jump out back positive determining program, if can satisfy condition A, then enters back positive armed state.When being in back positive armed state,, then enter back positive initial state, and when returning positive initial state,, return back positive armed state again as if satisfying condition C if satisfy condition B.When being in back positive armed state, the D that satisfies condition enters back and just begins and can move.If satisfy condition E or do not satisfy condition C and D, return back and just judge state.

Wherein,

A: corner is greater than setting value 1;

B: the corner direction is opposite with rotary speed direction;

C: operating torque is greater than setting value 2;

D: corner direction and operating torque opposite with rotary speed direction is less than setting value 2;

E: corner is less than setting value 3;

Return positive judge module and determined whether will apply aligning torque.

The implementation of aligning torque computing module can have following two kinds among the present invention:

A kind of is that to return with steering handwheel be the corner closed loop control of controlled target to midway location just, and returning with steering handwheel is being the corner loop control theory block diagram of controlled target to midway location just, as shown in Figure 3.This mode comprises a basic aligning torque and an integral element, or has the control system correction link of integral element.This basic aligning torque is a numerical value that changes with steering handwheel angle signal, and whether this numerical value control and export by returning positive judge module, returns promptly that basic aligning torque is the value of setting in the positive process, is 0 in the non-time positive process.

Among the present invention, the control system correction link is a proportional-integral-differential (PID) controlling unit, comprise a proportioning element (P), an integral element (I), a derivative element (D), these three links are a numerical value that changes with steering handwheel angle signal in the present invention, enable by returning positive judge module equally, that is, proportional-integral-differential (PID) link works in time positive process, is output as 0 in the non-time positive process.Because vehicle has the different positive characteristics of returning under the different speed of a motor vehicle, so in the present invention, the aligning torque and a velocity response multiplication calculated based on the corner closed loop control of proportional-integral-differential (PID) control with speed of a motor vehicle variation, under the different speed of a motor vehicle, only need to adjust this velocity response coefficient, just can demarcate the return performance of vehicle under the different speed of a motor vehicle.

Fig. 4 is being the real vehicle empirical curve of the corner closed loop control aligning torque method of calculating of controlled target to midway location just for returning with steering handwheel, wherein, test vehicle is certain minicar that is equipped with electric boosting steering system, when the speed of a motor vehicle is 20km/h, bearing circle is got to let go back about 180 degree and is just tested, by steering wheel angle-time history curve as can be seen, go back to positive final residue angle in 5 degree, presentation of results returns the return performance of positive control when having improved vehicle low speed.

Another aligning torque method of calculating is based on the corner closed-loop tracking control method of model following.This method comprises a desirable steering swivel system and returns positive model (referring to Fig. 5), this ideal model is output as desirable steering handwheel and returns positive corner-time history, the friction drag of this ideal model hypothesis electric boosting steering system is 0, turn to rigidity and setting value 2 to turn to damping by the setting value 1 that this ideal steering swivel system returns positive model is set under the different speed of a motor vehicle, can provide one to return positive process for the different speed of a motor vehicle desirable.The output of this model enables by returning positive judge module, that is, in non-time positive process, the output angle of this model is 0.If be in back positive status, one of them case study on implementation that calculates based on the corner closed-loop tracking aligning torque of model following is: the state that returns positive model according to desirable steering swivel system returns the poor of positive state with actual steering swivel system, by an integral element, or have a control system correction link of integral element, in the present invention, this control system correction link is proportional-integral-differential (PID) control, calculate the corresponding positive control moment of returning, in returning positive process, make motor output add back positive control moment.This proportional-integral-differential (PID) link enables by returning positive judge module, that is, proportional-integral-differential (PID) link works in time positive process, is output as 0 in the non-time positive process.Another one case study on implementation based on the corner closed-loop tracking aligning torque method of calculating of model following is: if be in back positive status, then the state that returns positive model according to desirable steering swivel system returns the poor of positive state with actual steering swivel system, the variation of the difference of state and steering wheel angle signal, by the fuzzy self-adaption control law, calculate the corresponding positive control moment of returning, in returning positive process, make motor output add back positive control moment.

Described corner closed-loop tracking aligning torque method of calculating based on model following comprises a desirable steering swivel system and returns positive model, and the difference of this ideal model and actual steering system is that it has ignored the friction of steering swivel system, supposes that promptly friction force is 0.Steering swivel system can be reduced to a single-degree-of-freedom system, as shown in Figure 5, can be with steering handwheel, Steering gear, deflector and the whole equivalences of front-wheel rotor inertia are transformed on the steering shaft axis, and note is made Is; With Steering gear, the whole equivalences of the damping that deflector and stub etc. is located are transformed on the Steering gear axis, are designated as Cs; With Steering gear, deflector, the whole equivalences of friction force that steering track rod bulb etc. is located are transformed on the Steering gear axis, are designated as Fs; Effect has the operating torque Th of chaufeur on the steering handwheel, and steering wheel angle is designated as α; Suppose to be rigid attachment between steering handwheel and the front-wheel, the motion between them meets the relation that transmitting ratio determines, steering gear ratio is designated as ns; Effect has aligning torque Tw on the front-wheel, and front wheel angle is designated as δ; The differential equation of describing this steering swivel system dynamic characteristics is

$I_{\mathrm{<figure-callout\; id="2"\; label="s\; d"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">s</figure-callout>}}\frac{d^{}}{}\frac{{}^2\mathrm{\&alpha;}}{{\mathrm{<figure-callout\; id="2"\; label="dt"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">dt</figure-callout>}}^2}+C_s\frac{\mathrm{d\&alpha;}}{\mathrm{dt}}+F_s*\mathrm{sgn}\left(\frac{\mathrm{d\&alpha;}}{\mathrm{dt}}\right)=T_h+\frac{T_w}{n_s}---\left(1\right)$

Suppose to adopt two degrees of freedom auto model and linear tire model, and only consider the aligning torque that causes by side force, then being calculated as follows of Tw:

$\mathrm{mV}\frac{\mathrm{d\&beta;}}{\mathrm{dt}}+2(K_f+K_r)\mathrm{\&beta;}+[\mathrm{mV}+\frac{2(l_f{K}_f-l_r{K}_r)}{V}]r={2K}_f\mathrm{\&delta;}---\left(2\right)$

$2(l_f{K}_f-l_r{K}_r)\mathrm{\&beta;}+I\frac{\mathrm{dr}}{\mathrm{dt}}+\frac{2({\mathrm{<figure-callout\; id="2"\; label="l\; f"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">l</figure-callout>}}_f^{}+l_r^2{K}_r)}{V}r={2l}_f{K}_f\mathrm{\&delta;}---\left(3\right)$

$T_w=2\mathrm{\&xi;}{K}_f(\mathrm{\&beta;}+l_f\frac{r}{V}-\mathrm{\&delta;})---\left(4\right)$

Above parameter and variable list implication see the following form

Title	Symbol
		Vehicle mass	m
The Vehicular yaw rotor inertia	I
		The front-wheel cornering stiffness	K f
The trailing wheel cornering stiffness	K r
		Barycenter is to the front axle distance	L f
Barycenter is to the rear axle distance	L r
		Pneumatic trail	ξ
Steering swivel system inertia	I s
		Steering system damping (setting value 2)	C s
The steering swivel system friction	F s
		The sideslip angle at vehicle barycenter place	β
Vertical speed of a motor vehicle of vehicle	V
		The vehicle front-wheel corner	δ
The yaw velocity of vehicle	r

By automobile theory as can be known, at automobile normal running, when lateral acceleration was not very big, sideslip angle and lateral deviation power were approximate linear, and sideslip angle and steering wheel angle are also approximate linear.Therefore Tw and steering wheel angle are approximated to proportional relation, can cross steering torque that the 1rad angle will apply to revolution and be defined as and turn to rigidity (setting value 1), and Ks represents with symbol, therefore can use Ks α replacement

Formula then

(1) can be expressed as

$\left[\begin{array}{c}\frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">d</figure-callout>}}^2\mathrm{\&alpha;}}{{\mathrm{<figure-callout\; id="2"\; label="dt"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">dt</figure-callout>}}^2}\\ \frac{\mathrm{d\&alpha;}}{\mathrm{dt}}\end{array}\right]=\left[\begin{array}{cc}-\frac{\mathrm{Cs}}{\mathrm{Is}}& -\frac{\mathrm{Ks}}{\mathrm{Is}}\\ 1& 0\end{array}\right]\left[\begin{array}{c}\frac{\mathrm{d\&alpha;}}{\mathrm{dt}}\\ \mathrm{\&alpha;}\end{array}\right]+\left[\begin{array}{c}\frac{1}{\mathrm{Is}}\\ 0\end{array}\right](-\mathrm{Fs}+\mathrm{Th})---\left(5\right)$

Ignore the friction in the above model, then it is converted into as drag,

$\left[\begin{array}{c}\frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">d</figure-callout>}}^2\mathrm{\&alpha;}}{{\mathrm{<figure-callout\; id="2"\; label="dt"\; filenames="H200910054150XE0000061.png,H200910054150XE0000071.png"\; state="\{\{state\}\}">dt</figure-callout>}}^2}\\ \frac{\mathrm{d\&alpha;}}{\mathrm{dt}}\end{array}\right]=\left[\begin{array}{cc}-\frac{\mathrm{Cs}}{\mathrm{Is}}& -\frac{\mathrm{Ks}}{\mathrm{Is}}\\ 1& 0\end{array}\right]\left[\begin{array}{c}\frac{\mathrm{d\&alpha;}}{\mathrm{dt}}\\ \mathrm{\&alpha;}\end{array}\right]+\left[\begin{array}{c}\frac{1}{\mathrm{Is}}\\ 0\end{array}\right]T_h---\left(6\right)$

Wherein, Th is the operating torque of chaufeur, is just to let go back if return positive process, Th approximates 0, and like this, time positive process of desirable steering swivel system is equivalent to the zero input response of a representative type second order link, as long as the Ks of setting value 1 and the Cs of setting value 2 suitably are set, promptly as long as satisfy

$C_s^2-{4I}_s{K}_s>0---\left(7\right)$

System is the overdamping system, returns timing and neither can produce overshoot, also can not produce residual corner, and this is the desirable positive process of returning.Fig. 6 be after simplifying the steering swivel system that has friction with simplify after do not have the steering swivel system of friction in the process of timing of letting go back.

By returning the positive enable signal that returns of positive status judge module, can begin back the quantity of state of timing to the actual steering system, be that the ideal that steering wheel angle and steering handwheel rotating speed pass to back in the positive control module turns to reference model, enable ideal simultaneously and turn to reference model, make the desirable steering handwheel of its output return positive corner-time history.

The wherein a kind of case study on implementation that calculates based on the corner closed-loop tracking aligning torque of model following is, desirable steering handwheel returns positive corner-time history as the reference signal, poor by desirable steering wheel angle and actual steering dish corner, introduce proportional-integral-differential (PID) control, apply additional aligning torque to system, offset friction force, can not return positive situation fully thereby eliminate bearing circle.Control block diagram such as Fig. 7 that it is basic.The tire aligning force is input to the desirable positive reference model that returns, the desirable reference state of positive reference model output that returns exports the PI controller to, PI controller control EPS motor, EPS motor-driven actual steering system, and existing condition of actual steering system outlet is to the PI controller.

Employing has the initiatively electric boosting steering system of aligning control function, lets go back under the different speed of a motor vehicle and just tests, and the test results of Fig. 8-Figure 10 has been verified the validity of native system.

In the test speed of a motor vehicle is 20km/h, carries out under the positive situation that begins to let go back about 180 degree.The time history of the steering wheel angle of Fig. 8 when not having back positive control and positive control is arranged back contrasts.As can be seen from the figure, when not having back positive control, chaufeur is let go behind the 3s, and residual steering wheel angle is for being about 50 °; And when positive control was arranged back, chaufeur was let go behind the 3s, and residual steering wheel angle is in 5 °.Presentation of results returns the return performance of positive control when having improved vehicle low speed.

Simultaneously, under the identical test situation, after turning over 180 °, steering handwheel just lets go back, when returning just to 60 °, carry out steering operation again, shown in Fig. 9 red circle, at the switching instant of just letting go back with steering operation, the sudden change of steering torque does not take place, thereby returns positive control and bring influence can for the feel of chaufeur.

Simultaneously, be under the situation of 10km/h in the speed of a motor vehicle, also carried out time just testing.Under the different speed of a motor vehicle, the parameter of returning positive reference model is also different, and under the low speed of a motor vehicle, time positive damping coefficient setting is bigger.When Figure 10 is the 10km/h and the 20km/h speed of a motor vehicle, reference model output and actual rotational angle output, Shi Ji corner can just return according to reference model substantially as can be seen.

Another case study on implementation that calculates based on the corner closed-loop tracking aligning torque of model following is the model following Fuzzy Adaptive Control Scheme.The difference of itself and above model following implementation method is: its follow-up control rule has adopted the method for fuzzy self-adaption control, rather than PID control.Adaptive fuzzy control system is a kind of learning control system, and it can continuous Correction and Control be restrained in operational process, to improve controller performance.Its major advantage is: insensitive to parameter variation and environmental change, can be used for complicated nonlinear system, and fast convergence rate.Because returning positive model, the steering swivel system of above foundation replaces with Ks α

And T _wChange with the speed of a motor vehicle, so the parameter perturbation that actual steering swivel system exists greatly along with the speed of a motor vehicle changes.Traditional PID is controlled at its tracking performance meeting variation in this case.Therefore adopting the stronger fuzzy self-adaption of robustness to control realizes.

Figure 11 is the block diagram based on the control of model following fuzzy self-adaption, reference of returning positive reference model exported and the real output of a part of actual steering system input in the fuzzy self-adaption mechanism after gathering, and the real output of another part actual steering system are directly inputted to fuzzy self-adaption mechanism, the actual steering system that exports to of fuzzy self-adaption mechanism.

The input of fuzzy self-adaption mechanism has three: with reference to the difference E of output with real output, the variation EC of E, and steering wheel angle α.The control law of E and EC such as following table

Wherein, NB, NM, NS, ZO, PS, PM, PB represent negative big respectively, and be negative little in bearing, zero, and just little, the center, honest.

Introduce the output coefficient of steering wheel angle as above output simultaneously, return when being in big corner, because the aligning force of steering swivel system self is bigger, required control aligning force is less, so output coefficient is less; During little corner, the aligning force of steering swivel system self is not enough to overcome friction, at this moment needs bigger control aligning force, so it is bigger to return positive coefficient.

Can obtain the fuzzy control rule of one 4 dimension according to above three input variables.Figure 12 is the 3 dimension enquiry forms of input/output variable through the aligning torque under certain corner after the normalization method.

In the test speed of a motor vehicle is 20km/h, and the vehicle lateral acceleration is about 3m/s ²Situation under let go back and just test.The time history of Figure 13 steering wheel angle when not having back positive control and positive control is arranged back contrasts.As can be seen from the figure, when not having back positive control, chaufeur is let go behind the 3s, and residual steering wheel angle is for being about 35 °; And when positive control was arranged back, chaufeur was let go behind the 3s, and residual steering wheel angle is in 5 °.Presentation of results returns positive control and has improved the return performance of vehicle when low speed.

Under the different speed of a motor vehicle, the parameter of returning positive reference model is also different.When Figure 14 is the 10km/h and the 20km/h speed of a motor vehicle, reference model output and actual rotational angle output.As can be seen, under the different speed of a motor vehicle, actual corner can just return according to different reference models, to realize the desired positive process of returning.

The above-mentioned description to three kinds of embodiment is can understand and apply the invention for ease of those skilled in the art.The person skilled in the art obviously can easily make various modifications to these embodiment, and needn't pass through performing creative labour being applied in the General Principle of this explanation among other embodiment.Therefore, the invention is not restricted to the embodiment here, those skilled in the art should be within protection scope of the present invention for improvement and modification that the present invention makes according to announcement of the present invention.

Claims (14)

1. one kind has the initiatively electric boosting steering system of aligning control function, comprises the mechanical steering system, torque sensor, steering wheel angle sensor, car speed sensor, electronic control unit, power steering motor and speed reduction gearing thereof; Wherein, described torque sensor is installed on the steering shaft of described mechanical steering system to detect pilot control moment and output torque signal; Steering wheel angle sensor is used to detect the angle signal of steering handwheel off-straight traveling-position and output; Car speed sensor is used to detect the moving velocity of present vehicle and exports vehicle speed signal; The driving current value that need provide for the power steering motor is provided electronic control unit; The power steering motor can be installed in mechanical steering axle or the deflector, provides assist torque by speed reduction gearing to chaufeur; Described electronic control unit comprises Torque Control module, current of electric control module and fault diagnosis module; The Torque Control module is accepted torque signal, vehicle speed signal and angle signal, this Torque Control module comprises basic power operated control module, initiatively return the positive control module, damping control module, the input end of three control modules and torque sensor, steering wheel angle sensor, car speed sensor connects, accept torque signal, vehicle speed signal and angle signal, the mouth of three control modules is connected with the current of electric control module, to current of electric control module output control signal, it is characterized in that, the described positive control module of initiatively returning comprises back positive judge module and aligning torque computing module, return the input end and the torque sensor of positive judge module, steering wheel angle sensor, car speed sensor connects, accept torque signal, vehicle speed signal and angle signal, judge whether steering handwheel is in back positive status, if be in back positive status, then return positive judge module and signal is sent to the aligning torque computing module that initiatively returns in the positive control module, the aligning torque computing module calculates suitable time positive control moment, and exports corresponding aligning torque by current of electric control module control power steering motor.The present invention utilizes the steering wheel angle signal, torque signal, and vehicle speed signal returns positive control, is applicable to the electric boosting steering system of various assist types, improves the return performance of vehicle, can not influence the manipulation feel of chaufeur simultaneously.

2. the electric boosting steering system with active aligning control function according to claim 1 is characterized in that described time positive judge module judges according to angular signal, bearing circle tach signal, torque signal whether vehicle is in back positive status.

3. the electric boosting steering system with active aligning control function according to claim 2, it is characterized in that, the design of returning positive judge module of initiatively returning in the positive control module is based on the state machine theory, by just being decomposed into back, the steering reversal operation judges, return and just await orders, return and just to begin three kinds of states, judge the current aligning torque that whether needs to apply by angular signal, bearing circle tach signal, torque signal again.

4. according to claim 2 or 3 described electric boosting steering systems, it is characterized in that described bearing circle tach signal can be obtained by the angular signal differential, perhaps obtain by the estimation of power steering motor speed with active aligning control function.

5. the electric boosting steering system with active aligning control function according to claim 1, it is characterized in that, initiatively return aligning torque computing module that the positive control module comprised according to current angular signal, vehicle speed signal calculates back and just arrives the needed aligning torque of steering handwheel midway location.

6. the electric boosting steering system with active aligning control function according to claim 5, it is characterized in that a kind of control method of described aligning torque computing module is: it is being the corner closed loop control of controlled target to midway location just that employing is returned with steering handwheel.

7. the electric boosting steering system with active aligning control function according to claim 5 is characterized in that another control method of described aligning torque computing module is: adopt the corner closed-loop tracking control based on the model following control method.

8. the electric boosting steering system with active aligning control function according to claim 6, it is characterized in that, described returning with steering handwheel is being the corner closed loop control method of calculating of controlled target to midway location just, comprise a basic aligning torque, this basic aligning torque is a constant, an or numerical value that changes with angle signal or vehicle speed signal, or numerical value that calculates according to state of motion of vehicle.

9. the electric boosting steering system with active aligning control function according to claim 8 is characterized in that described numerical value is enabled by described time positive judge module, that is, basic aligning torque is the value of setting in time positive process, is 0 in the non-time positive process.

10. the electric boosting steering system with active aligning control function according to claim 6, it is characterized in that, described returning with steering handwheel is being the corner closed loop control method of calculating of controlled target to midway location just, at least comprise an integral element, or have a control system correction link of integral element, and this integral element or the control system correction link that has integral element are enabled by described time positive judge module, promptly, return that this link enables in the positive process, be output as 0 in the non-time positive process.

11. the electric boosting steering system with active aligning control function according to claim 7, it is characterized in that, described corner closed-loop tracking aligning torque method of calculating based on model following, comprise a desirable steering swivel system and return positive model, this desirable steering swivel system returns positive model and is output as desirable steering handwheel and returns positive corner-time history, the friction drag that the desirable steering swivel system of this commentaries on classics returns positive model hypothesis electric boosting steering system is 0, by setting value 1 and the setting value 2 that this ideal steering swivel system returns positive model is set, can provide a desirable time positive process for the different speed of a motor vehicle under the different speed of a motor vehicle; Described desirable steering swivel system returns positive model output and is enabled by described time positive judge module, that is, in non-time positive process, the output angle of this model is 0.

12. the electric boosting steering system with active aligning control function according to claim 7, it is characterized in that, wherein a kind of implementation of described corner closed-loop tracking aligning torque method of calculating based on model following is: if be in back positive status, then the state that returns positive model according to desirable steering swivel system returns the poor of positive state with actual steering swivel system, by an integral element, or have a control system correction link of integral element, calculate the corresponding positive control moment of returning, in returning positive process, make motor output add back positive control moment; Described integral element or the control system correction link that has integral element are enabled by described time positive judge module,, return that this link works in the positive process that is, are output as 0 in the non-time positive process.

13. the electric boosting steering system with active aligning control function according to claim 7, it is characterized in that, another implementation of described corner closed-loop tracking aligning torque method of calculating based on model following is: if be in back positive status, then the state that returns positive model according to desirable steering swivel system returns the poor of positive state with actual steering swivel system, the variation of the difference of state and steering wheel angle signal, by the fuzzy self-adaption control law, calculate the corresponding positive control moment of returning, in returning positive process, make motor output add back positive control moment.

14. the electric boosting steering system with active aligning control function according to claim 1 is characterized in that, returns the residual angle of positive steering handwheel less than 5 degree, can not influence the manipulation feel of chaufeur simultaneously.

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