CN112441109B - Continuously-learned steering system friction torque compensation method - Google Patents
Continuously-learned steering system friction torque compensation method Download PDFInfo
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- CN112441109B CN112441109B CN201910825631.XA CN201910825631A CN112441109B CN 112441109 B CN112441109 B CN 112441109B CN 201910825631 A CN201910825631 A CN 201910825631A CN 112441109 B CN112441109 B CN 112441109B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
- B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D15/00—Steering not otherwise provided for
- B62D15/02—Steering position indicators ; Steering position determination; Steering aids
- B62D15/025—Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
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- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
Abstract
The invention relates to the technical field of an electric power-assisted steering system of an automobile and power-assisted fluctuation suppression thereof, in particular to a friction torque compensation method of a continuously-learned steering system, which calculates resultant torque T acting on the steering systemsysThe steering inflection point B of the steering wheel is positioned, the average value of the resultant moment of the steering system in the process from the steering starting point A to the steering starting point B and the average value T of the resultant moment in the process from the steering starting point C to the steering correcting starting point D are calculatedsys,avg2Calculating self-learning friction torque T of steering systemfrie,learnAnd finally, judging the hand torque of the steering wheel and performing friction compensation, wherein the device has a continuous self-learning function, so that the abrasion of the steering system can be continuously detected and learned, the influence on the steering hand feeling can be eliminated, the hand feeling consistency of the electronic power-assisted steering system under long-time use is ensured, and the stability of the friction compensation torque is ensured.
Description
Technical Field
The invention relates to the technical field of an electric power-assisted steering system of an automobile and power-assisted fluctuation suppression thereof, in particular to a friction torque compensation method of a continuously-learned steering system.
Background
In the process of electric power steering, because a plurality of pairs of kinematic pairs exist in the whole steering system, when a driver operates a steering wheel, the resistance moment caused by wheel load needs to be overcome, and the resistance moment caused by friction in the steering system also needs to be overcome. As the steering system is used for a longer time, the transmission parts inside the steering system are worn, and the frictional resistance of the steering system is increased, so that the steering system feels heavier.
In the prior art, the friction force of a system is generally compensated through a fixed friction compensation curve, but as a mechanical structure ages, the friction coefficient changes, and the original fixed friction compensation curve cannot meet the requirement of a steering system with mechanical ageing.
Therefore, in order to ensure the constancy of the steering feel during the long-term use of the steering system, it is necessary to design a continuously-learned steering system friction torque compensation method.
Disclosure of Invention
The invention breaks through the difficult problems in the prior art, and designs a continuously-learned steering system friction torque compensation method for ensuring the constancy of steering hand feeling in the long-time use process of the steering system.
In order to achieve the above object, the present invention provides a continuously learning method for compensating a friction torque of a steering system, comprising: the method comprises the following steps:
step 1: enabling the driving state to meet the judgment condition of friction compensation self-learning, wherein the friction compensation self-learning means that the vehicle automatically learns the friction of the system through an algorithm so as to compensate the friction of the system;
step 2: calculating the resultant torque T acting on the steering systemsysThe size of (d);
and step 3: positioning a steering inflection point B of a steering wheel;
and 4, step 4: recording the resultant torque of the steering system in the process from the steering starting point A to the steering starting point B and calculating the average value T of the resultant torquesys,avg1；
And 5: calculating the resultant torque of the steering system in the process from the steering return starting point C to the steering return ending point D and calculating the average value T of the resultant torquesys,avg2；
Step 6: calculating the friction torque T of a steering systemfrie；
And 7: calculating self-learning friction torque T of steering systemfrie,learn；
And 8: judging the hand moment of the steering wheel, and when the absolute value of the hand moment of the steering wheel is smaller than the friction compensation enabling threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a decreasing gradient TGradDownGradually decreasing to 0;
when the absolute value of the hand moment of the steering wheel is larger than the threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a rising gradient TGradUpIncrease, but not exceed, the friction compensation end value
。
The friction compensation enabling threshold value is a numerical value used for judging whether friction compensation needs to be provided or not in the running process of the vehicle, and is generally in the range of 0-1 Nm in specific setting.
The determination conditions in the step 1 are as follows:
(1) the speed of the automobile is greater than the lowest speed limit and less than the highest speed limit;
(2) the absolute value of the steering wheel angle is smaller than the maximum limit value of the steering wheel angle;
(3) the rotating angular speed of the steering wheel is greater than the angular speed minimum limit and less than the angular speed maximum limit;
(4) the change rate of the sum of the hand torque of the steering wheel and the torque of the motor is smaller than the maximum limit value of the change rate of the torque.
Said step 2
Wherein T ishandFor steering wheel hand torque, TmotorAnd outputting torque for the motor.
The method for positioning the steering inflection point B of the steering wheel in the step 3 comprises the following steps: recording the resultant torque T of the current steering systemsysAnd steering wheel angle thetastrAnd according to the steering wheel angle thetastrTo determine a change in steering, i.e. when thetastrWhen the increase is changed to the decrease, the turning point in this turning cycle is the steering wheel turning point B.
Step 5, calculating the resultant torque of the steering system in the process of steering back to the initial point C to D and calculating the average value T of the resultant torquesys,avg2The method comprises the following steps: when the turning point of the steering wheel occurs again, recording the current steering wheel turning angle thetastr,maxSubtracting the angle of rotation of the vacancy shift from the B to C processθ str,offset To obtain a rotation angle theta of the steering return to the normal start point position Cstr,deadRecording is started from point C, and when an inflection point occurs, the inflection point is set as the switchbackAnd (4) a positive end point D, recording the resultant torque of the steering system between the processes C and D, and calculating the average value of the resultant torque, namely Tsys,avg2。
The friction torque of the steering system in step 6
。
Said step 7
Wherein alpha is a filter coefficient and is a constant value calibrated according to an actual system,
the friction torque is self-learned in the last sampling period.
In said step 8
And k is a compensation value coefficient, and a constant ranging from 0 to 100 percent is determined according to the final hand feeling expression of the system.
Friction compensation enabling threshold value T in step 8comp,enableThe numerical range of (A) is 0 to 1 Nm.
Falling gradient T in step 8GradDownAnd a rising gradient TGradUpAll of which are 0 to 0.2 Nm/ms.
Compared with the prior art, the friction compensation method has a continuous self-learning function, so that the abrasion of the steering system can be continuously detected and learned, the influence of the abrasion on the steering hand feeling can be eliminated by the friction compensation method designed by the invention, and the hand feeling consistency of the electronic power-assisted steering system under the long-time use is ensured; the influence of the hand torque of the steering wheel during zero jump is considered during calculation, the intervention of the friction compensation torque is processed by the designed method, and the stability of the friction compensation torque is ensured.
Drawings
Fig. 1 is a schematic view of the operation of the steering system under a small working load in the present invention.
Detailed Description
In the concrete implementation, the invention designs a continuously-learned friction torque compensation method for a steering system, which comprises the following steps:
step 1: carrying out condition judgment on the friction compensation self-learning, and entering compensation when the condition is met;
step 2: calculating the resultant torque T acting on the steering systemsysThe size of (d);
and step 3: positioning a steering inflection point B of a steering wheel;
and 4, step 4: recording the resultant torque of the steering system in the process from A to B and calculating the average value T of the resultant torquesys,avg1；
And 5: calculating the resultant torque of the steering system in the process from the steering return starting point C to the steering return ending point D and calculating the average value T of the resultant torquesys,avg2；
Step 6: calculating the friction torque T of a steering systemfrie；
And 7: calculating self-learning friction torque T of steering systemfrie,learn；
And 8: judging the hand moment of the steering wheel, and when the absolute value of the hand moment of the steering wheel is smaller than the friction compensation enabling threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a decreasing gradient TGradDownGradually decreasing to 0;
when the absolute value of the hand moment of the steering wheel is larger than the threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a rising gradient TGradUpIncrease, but not exceed, the friction compensation end value
。
Wherein the friction compensation enables a threshold value Tcomp,enableThe method is a numerical value for judging whether friction compensation is required or not in the running process of the vehicle, and the range is 0-1 Nm.
In which the gradient T is decreasedGradDownAnd a rising gradient TGradUpAll of which are 0 to 0.2 Nm/ms.
Wherein
And k is a compensation value coefficient range between 0 and 100 percent, and a calibration value is determined according to the final hand feeling performance of the system.
The determination conditions in step 1 of the present invention are:
(1) the vehicle speed is greater than the vehicle speed minimum limit condition and less than the vehicle speed maximum limit condition;
(2) the absolute value of the steering wheel angle is smaller than the maximum limit condition of the steering wheel angle;
(3) the steering wheel rotating angular speed is greater than the angular speed minimum condition and less than the angular speed maximum condition;
(4) the change rate of the sum of the hand torque of the steering wheel and the torque of the motor is smaller than the maximum limit value condition of the change rate of the torque.
In step 2 of the present invention
Wherein T ishandFor steering wheel hand torque, TmotorAnd outputting torque for the motor.
Referring to fig. 1, the method for locating the steering inflection point B of the steering wheel in step 3 of the present invention comprises: recording the resultant torque T of the current steering systemsysAnd steering wheel angle thetastrAnd according to the steering wheel angle thetastrThe steering change is judged, and the steering inflection point B of the steering wheel is located.
In the invention, in the step 5, the steering system resultant moment in the process of steering system returning to the initial points C to D is calculated, and the average value T of the steering system resultant moment in the process of steering system returning to the initial points C to D is calculatedsys,avg2The method comprises the following steps: when the turning point of the steering wheel occurs again after the turning point of the point B, the secondary turning point is recorded as the point C, namely the turning point of the steering wheel returns to the positive starting point, and the current steering wheel turning angle theta is recordedstr,maxSubtracting the angle of rotation theta of the vacancy shift from the B to C processstr,offsetTo obtain a rotation angle theta of the steering return to the normal start point position Cstr,deadRecording from the point C, setting the inflection point as a steering reversal end point D when the inflection point occurs, and recording the resultant moment of the steering system between the processes of C and DThen calculating the average value of the values and recording the average value as Tsys,avg2。
In step 6 of the present invention
。
In step 7 of the present invention
Wherein alpha is a filter coefficient and is a constant value obtained by calibration according to an actual system, and the range is 0-1,
the friction torque is self-learned in the last sampling period.
In the implementation, a turning and returning process is simply described by using fig. 1, wherein a is a turning starting point; b is a turning point; c is the steering return starting point, and a section of empty displacement theta exists between B and C because of the existence of mechanical clearancestr,offsetAnd D is the steering back to the positive end point.
In the driving process of a driver, the vehicle speed, the steering wheel angle, the steering wheel turning speed, the steering wheel hand torque, the motor torque change rate and other parameters meet the judgment conditions in the step 1, the driver turns the steering wheel to the right from the starting position A of the steering wheel turning angle to the position B and then returns to the steering wheel turning angle position D through the point C, the turning and returning process is taken as an example, and the calculation process of friction compensation learning and compensation in the process is as follows:
first, the average resultant system force in the process from A to B is calculated
(ii) a Then, positioning the position of the C: thetastr,dead=θstr,max-θstr,offset(ii) a And then calculating the resultant force of the system in the process from C to D
(ii) a Thereafter calculating the frictional force
(ii) a Then, according to the constant value of alpha obtained by actual system calibration, the constant value is substituted into a formula to calculate the friction force learning value:
，
self-learning friction torque for the last sampling period; then, determining the value of a compensation value coefficient k according to the final hand feeling expression of the system, and calculating a friction compensation final value:
。
the calculation process is a continuous and cyclic self-learning process, in the cyclic self-learning process, the alpha value is a filter coefficient and is a constant value obtained according to actual system calibration, k is a compensation value setting coefficient larger than 0, the constant is in the range of 0-100%, and the calibration is carried out according to the final hand feeling performance of the system.
If the absolute value of the hand moment of the steering wheel of the driver in the process of driving the vehicle at the later time is smaller than the friction compensation enabling threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a decreasing gradient TGradDownGradually decreases to 0.
If the absolute value of the hand moment of the steering wheel is larger than the threshold value T in the process of driving the driver at the later timecomp,enableWhile setting a friction compensation torque value TcompAccording to a rising gradient TGradUpIncrease, but not exceed, the friction compensation end value
。
Claims (7)
1. A continuously-learned friction torque compensation method for a steering system is characterized in that: the method comprises the following steps:
step 1: enabling the driving state to meet the judgment condition of friction compensation self-learning;
step 2: calculating effect on steering systemResultant moment TsysThe size of (d);
and step 3: positioning a steering inflection point B of a steering wheel;
and 4, step 4: recording the resultant torque of the steering system in the process from the steering starting point A to the steering starting point B and calculating the average value T of the resultant torquesys,avg1；
And 5: calculating the resultant torque of the steering system in the process from the steering return starting point C to the steering return ending point D and calculating the average value T of the resultant torquesys,avg2；
Step 6: calculating the friction torque T of a steering systemfrie，
；
And 7: calculating self-learning friction torque T of steering systemfrie,learn，
Wherein alpha is a filter coefficient in the range of 0 to 1,
self-learning friction torque for the last sampling period;
and 8: judging and compensating the hand torque of the steering wheel, and when the absolute value of the hand torque of the steering wheel is smaller than the friction compensation enabling threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a decreasing gradient TGradDownGradually decreasing to 0;
when the absolute value of the hand moment of the steering wheel is larger than the threshold value Tcomp,enableWhile setting a friction compensation torque value TcompAccording to a rising gradient TGradUpIncrease, but not exceed, the friction compensation end value
Final value of friction compensation
Where k is a compensation value setting coefficient greater than 0, rangeBetween 0 and 100%.
2. The continuously learned steering system friction torque compensation method according to claim 1, characterized in that: the determination conditions in step 1 are:
(1) the speed of the automobile is greater than the lowest speed limit and less than the highest speed limit;
(2) the absolute value of the steering wheel angle is smaller than the maximum limit value of the steering wheel angle;
(3) the rotating angular speed of the steering wheel is greater than the angular speed minimum limit and less than the angular speed maximum limit;
(4) the change rate of the sum of the hand torque of the steering wheel and the torque of the motor is smaller than the maximum limit value of the change rate of the torque;
the satisfaction of the determination condition means that the above 4 conditions are simultaneously satisfied.
3. The continuously learned steering system friction torque compensation method according to claim 1, characterized in that: in step 2
Wherein T ishandFor steering wheel hand torque, TmotorAnd outputting torque for the motor.
4. The continuously learned steering system friction torque compensation method according to claim 1, characterized in that: the method for positioning the steering inflection point B of the steering wheel in the step 3 comprises the following steps: recording the resultant torque T of the current steering systemsysAnd steering wheel angle thetastrAnd according to the steering wheel angle thetastrTo determine a change in steering, i.e.: when theta isstrWhen the increase is changed to the decrease, the turning point in this turning cycle is the steering wheel turning point B.
5. The continuously learned steering system friction torque compensation method according to claim 1, characterized in that: calculating a steering system in the steering system process in the steering return to the starting point C to D in step 5Integrating the moments and calculating the mean value T thereofsys,avg2The method comprises the following steps: when the turning point of the steering wheel occurs again, recording the current steering wheel turning angle thetastr,maxSubtracting the angle of rotation of the vacancy shift from the B to C processθ str,offset To obtain a rotation angle theta of the steering return to the normal start point position Cstr,deadRecording from the point C, setting the inflection point as the steering return-to-normal end point D when the inflection point occurs, recording the resultant torque of the steering system between the processes of C and D, and calculating the average value of the resultant torque, which is recorded as Tsys,avg2。
6. The continuously learned steering system friction torque compensation method according to claim 1, characterized in that: friction compensation enabling threshold value T in step 8comp,enableThe numerical range of (A) is 0 to 1 Nm.
7. The continuously learned steering system friction torque compensation method according to claim 1, characterized in that: falling gradient T in step 8GradDownAnd a rising gradient TGradUpAll of which are 0 to 0.2 Nm/ms.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2669146A2 (en) * | 2012-06-01 | 2013-12-04 | Steering Solutions IP Holding Corporation | Average friction learning and average friction change estimation |
| CN105270470A (en) * | 2014-05-28 | 2016-01-27 | 现代摩比斯株式会社 | Device and method for compensating friction of a motor driven power steering system |
| CN106064639A (en) * | 2015-04-20 | 2016-11-02 | 奥迪股份公司 | The method turning to behavior is improved in the motor vehicles with superposition steering mechanism |
| CN106627748A (en) * | 2016-05-26 | 2017-05-10 | 上海拿森汽车电子有限公司 | Electric power steering system with friction identification function |
| CN107031707A (en) * | 2015-12-04 | 2017-08-11 | 现代自动车株式会社 | Device and method for controlled motor driving power steering system |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2669146A2 (en) * | 2012-06-01 | 2013-12-04 | Steering Solutions IP Holding Corporation | Average friction learning and average friction change estimation |
| CN105270470A (en) * | 2014-05-28 | 2016-01-27 | 现代摩比斯株式会社 | Device and method for compensating friction of a motor driven power steering system |
| CN106064639A (en) * | 2015-04-20 | 2016-11-02 | 奥迪股份公司 | The method turning to behavior is improved in the motor vehicles with superposition steering mechanism |
| CN107031707A (en) * | 2015-12-04 | 2017-08-11 | 现代自动车株式会社 | Device and method for controlled motor driving power steering system |
| CN106627748A (en) * | 2016-05-26 | 2017-05-10 | 上海拿森汽车电子有限公司 | Electric power steering system with friction identification function |
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