CN111216788B - Electric power steering fuzzy correction method - Google Patents
Electric power steering fuzzy correction method Download PDFInfo
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- CN111216788B CN111216788B CN202010109081.4A CN202010109081A CN111216788B CN 111216788 B CN111216788 B CN 111216788B CN 202010109081 A CN202010109081 A CN 202010109081A CN 111216788 B CN111216788 B CN 111216788B
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- electric power
- power steering
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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
- B62D5/046—Controlling the motor
- B62D5/0466—Controlling the motor for returning the steering wheel to neutral position
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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
- B62D5/046—Controlling the motor
- B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
Abstract
An electric power steering fuzzy correction method relates to the technical field of electric power steering, and comprises the following steps: s01, setting an assistance current threshold of the EPS, integrating assistance current in real time when the assistance current is increased, and integrating the return current obtained in the previous period in real time when the assistance current is smaller than the assistance current threshold; s02, equating the integration result obtained in the step S01 to be a steering wheel angle, and obtaining the current return-to-positive basic current and the return-to-positive current through table look-up; s03, calibrating adjustment factors of left aligning and right aligning of the steering wheel, and correcting the aligning current obtained in the step S02 by using the adjustment factors; and S04, superposing the boosting current and the corrected return positive current in the step S03 into a target current to perform current loop control on the EPS, and repeating the steps S01-S03. The electric power steering fuzzy correction method can improve the correction effect of the whole vehicle.
Description
Technical Field
The invention relates to the technical field of electric power steering, in particular to an electric power steering fuzzy correction method.
Background
For an electric power-assisted vehicle, the aligning performance of an electric power steering system (EPS) is particularly important, and is an important index for judging the driving experience. At present, due to the limitation of cost, most of grade a vehicles and fabric-covered vehicles on the market are provided with no angle sensor, as is well known, the angle sensor is an important component for obtaining the angle of a steering wheel by the EPS, and without the angle sensor, when the vehicle runs, the situation that the steering wheel alignment is insufficient due to the fact that the system cannot determine the alignment current of the EPS in real time according to the change of the angle of the steering wheel occurs, and the vehicle runs at a low speed obviously.
Disclosure of Invention
The invention aims to provide an electric power steering fuzzy correction method capable of improving the correction effect of a whole vehicle.
In order to solve the technical problem, the invention provides an electric power steering fuzzy correction method, which comprises the following steps:
s01, determining an integration object: setting an assistance current threshold of the EPS, integrating assistance current in real time when the assistance current is increased, and integrating the return current obtained in the previous period in real time when the assistance current is smaller than the assistance current threshold;
s02, determining the current positive feedback current: equating the integration result obtained in the step S01 to a steering wheel angle, and obtaining the current return-to-positive basic current and the return-to-positive current through table look-up;
s03, correcting: calibrating adjustment factors of left return correction and right return correction of the steering wheel according to the friction resistance of a steering system of the vehicle, and correcting the inherent deviation of the system of the return current obtained in the step S02 by using the adjustment factors;
s04, current loop control: and (4) superposing the boosting current and the corrected return positive current in the step (S03) into a target current to perform EPS current loop control, and repeating the steps (S01-S03) after a certain time interval.
Further, in step S01, the boost current threshold is less than or equal to 2A.
Furthermore, after the integration result obtained in step S01 is equivalent to the steering wheel angle in step S02, the magnitude of the return-positive base current is determined according to the relationship table between the steering wheel angle and the basic return-positive current, and then the magnitude of the current return-positive current is determined according to the relationship table between the percentage of the return-positive base current decreasing with the vehicle speed.
Further, in step S03, the adjustment factors for the left and right steering wheel return corrections are both 0.5-0.6.
Still further, in step S04, the ramp control is required to be performed on the return positive current when the vehicle starts and stops, the coefficient of the ramp control is 0.05 to 0.1, and the time limit value of the ramp control is 2 to 3S.
Preferably, in step S04, the time interval for repeating steps S01-S03 is 3-10ms.
The electric power steering fuzzy correction method provided by the invention utilizes the characteristic that a motor does work equivalently in the power assisting process and the correction process, integrates the power assisting current in the power assisting process and the correction current in the correction process respectively, calculates the correction current of the electric power steering system in real time according to the driving speed of a vehicle, corrects the correction current by fully considering the friction resistance of the system, realizes the current closed-loop control of EPS, and thus, a steering wheel can return to the position close to the midpoint. The method is simple and easy to realize, and can ensure that the vehicle without the angle sensor can have better aligning effect, thereby effectively solving the problem of insufficient aligning of the traditional vehicle under low-speed running.
Drawings
FIG. 1 is a current integral equivalent diagram of a motor boosting process and a return process in an electric power steering system;
FIG. 2 is a flow chart of an electric power steering fuzzy alignment method according to the present invention;
FIG. 3 is a graph of the return basic current varying with the steering wheel angle in the electric power steering fuzzy return method according to the present invention;
FIG. 4 is a graph of percentage of return basic current drop with vehicle speed in the electric power steering fuzzy return method according to the present invention;
fig. 5 is a graph showing the change of each current with time in the electric power steering fuzzy alignment method according to the present invention.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.
Before the present invention is explained, it should be noted that in the electric power steering system, the work of the motor in the power assisting process and the returning process is equivalent, and the steering wheel can be returned to the approximate middle point by using the special point. The calculation formula of the power W of the motor is as follows: w = UIt, wherein is the voltage of the battery, I is the current, and t is the working time. Because the voltage of the battery is basically kept unchanged in the whole working process of the system, the formula for doing work of the motor can be simplified for convenient calculation, namely, the current of the motor is integrated
To indicate that the motor is doing work. As shown in fig. 1, the integral of the assist time current is the area W1 of the diagonally shaded portion, and the integral of the return time current is the area W2 of the grid shaded portion, and the return effect can be ensured as long as W2 is ensured to be approximately equal to W1.
In view of the above, the present invention provides an electric power steering fuzzy alignment method for improving the alignment effect of the whole vehicle, as shown in fig. 2, the electric power steering fuzzy alignment method includes the following steps:
and S01, determining an integration object.
The system determines whether to integrate the boosting current or integrate the return current according to the boosting current of the system, the boosting current is calculated by the system according to a torque sensor, the boosting current is generated when the steering wheel is turned to the left or to the right, the system determines the integration object according to the absolute value of the boosting current, the boosting current is small and fluctuates around a zero value at the moment when the steering wheel is turned back from the stop, so that in order to enable the system to determine the change more quickly and accurately, a boosting current threshold value is set in the system, the boosting current threshold value can be 2A, when the absolute value of the boosting current is increased, the angle of the steering wheel is increased, the vehicle is in steering operation, the boosting current is integrated in real time, when the boosting current is smaller than the boosting current threshold value, the angle of the steering wheel is reduced, the vehicle is started to perform the return operation, and the return current obtained in the last period is integrated in real time (from step 01-04, namely, the time interval of each period is very short).
And S02, determining the current return positive current.
It is known that the output power of the motor is closely related to the input power of the motor, and in the same system, the output power of the motor is only related to the rotating speed of the motor, the input power depends on the current of the motor, and the corresponding relation between the current of the motor and the rotating speed can be obtained according to the relation between the output power and the input power of the motor. By using the principle, the corresponding relation between the motor current integration result of each automobile and the steering wheel angle can be obtained. As shown in fig. 5, the target current of the motor is equal to the sum of the boosting current and the returning positive current during boosting and the returning positive current is small and negative during boosting, so that the target current of the motor can be similar to the boosting current during this process, and the boosting current is zero during returning, so that the target current of the motor is equal to the returning positive current. Accordingly, in the present embodiment, the integration result obtained in real time in step S01 may be equivalent to the steering wheel angle, the return base current may be obtained according to the corresponding relationship between the return base current and the steering wheel angle as shown in fig. 3, and the return current may be obtained according to the relationship between the percentage of the return base current decreasing with the vehicle speed as shown in fig. 4 (the graphs shown in fig. 3 and 4 are pre-stored in the electric power steering system in a table form).
And S03, correcting.
In the automobile steering system, the friction resistance between the components can affect the return effect of the steering wheel, in order to ensure the left-right consistency of the return time, the adjustment factors of the left return and the right return of the steering wheel can be calibrated according to the friction resistance of the steering system of the automobile, and the adjustment factors are used for correcting the system inherent deviation of the return current obtained in the step S02. In the present embodiment, the adjustment factor for the left and right return-to-positive steering wheel may preferably be 0.6, and the return-to-positive current obtained in step S02 may be multiplied by 0.6 to obtain the corrected return-to-positive current.
And S04, current loop control.
In an electric power steering system, the current of a motor is controlled in a closed loop mode, and after a corrected return positive current is obtained, the power-assisted current and the corrected return positive current are overlapped to form a target current to perform current loop control on the EPS. It is worth mentioning that the return-to-positive control is not needed when the vehicle is in place, in order to enable the return-to-positive current to be in smooth transition when the vehicle starts and stops, the return-to-positive current can be subjected to slope control when the vehicle starts and stops, the coefficient of the slope control is 0.05-0.1, and the time limit value of the slope control is 2-3S. In the present embodiment, it is also important to repeat steps S01 to S03 every 5ms after the completion of the closed-loop control during the running of the vehicle in order to realize the real-time control of the electric power steering system for the blur restoration.
The above embodiments are preferred implementations of the present invention, and the present invention can be implemented in other ways without departing from the spirit of the present invention.
Some of the figures and descriptions of the present invention have been simplified to provide a convenient understanding of the modifications of the invention relative to the prior art, and to omit elements for clarity, as those skilled in the art will recognize may also constitute the subject matter of the present invention.
Claims (6)
1. An electric power steering fuzzy correction method is characterized by comprising the following steps:
s01, determining an integration object: setting an assistance current threshold of the EPS, integrating assistance current in real time when the assistance current is increased, and integrating the return positive current obtained in the previous period in real time when the assistance current is smaller than the assistance current threshold;
s02, determining the current positive feedback current: equating the integration result obtained in the step S01 to be a steering wheel angle, and obtaining the current return-to-positive basic current and the return-to-positive current through table look-up;
s03, correcting: calibrating adjustment factors of left return correction and right return correction of the steering wheel according to the friction resistance of a steering system of the vehicle, and correcting the inherent deviation of the system of the return current obtained in the step S02 by using the adjustment factors;
s04, current loop control: and (4) superposing the boosting current and the corrected return positive current in the step (S03) into a target current to perform EPS current loop control, and repeating the steps (S01-S03) after a certain time interval.
2. The electric power steering fuzzy alignment method according to claim 1, wherein: in step S01, the boost current threshold is less than or equal to 2A.
3. The electric power steering fuzzy alignment method according to claim 2, wherein: in step S02, after the integration result obtained in step S01 is equivalent to a steering wheel angle, the magnitude of the return-positive base current is determined according to a relation table between the steering wheel angle and the base return-positive current, and then the magnitude of the current return-positive current is determined according to a relation table between the percentage of the return-positive base current decreasing with the vehicle speed.
4. The electric power steering fuzzy regression method according to claim 3, wherein: in step S03, the adjustment factors for the left return and the right return of the steering wheel are both 0.5-0.6.
5. The electric power steering fuzzy alignment method according to claim 1 or 4, wherein: in step S04, the return positive current needs to be subjected to slope control when the vehicle starts and stops, the coefficient of the slope control is 0.05-0.1, and the time limit value of the slope control is 2-3S.
6. The electric power steering fuzzy alignment method according to claim 5, wherein: in step S04, the time interval for repeating steps S01-S03 is 3-10ms.
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| CN202010109081.4A CN111216788B (en) | 2020-02-21 | 2020-02-21 | Electric power steering fuzzy correction method |
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| CN202010109081.4A CN111216788B (en) | 2020-02-21 | 2020-02-21 | Electric power steering fuzzy correction method |
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| CN113942565B (en) * | 2021-10-14 | 2024-04-16 | 江门市兴江转向器有限公司 | Steering wheel aligning method and device and readable storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2000177615A (en) * | 1998-12-15 | 2000-06-27 | Toyoda Mach Works Ltd | Electric power steering device |
| JP2004255932A (en) * | 2003-02-24 | 2004-09-16 | Koyo Seiko Co Ltd | Electric power steering device |
| CN2647705Y (en) * | 2003-09-27 | 2004-10-13 | 江苏大学 | Electric power-assisted steering device with return control function |
| CN102530071A (en) * | 2011-12-21 | 2012-07-04 | 株洲易力达机电有限公司 | Electric power-assisted steering aligning controller without angle sensor |
| JP2015074287A (en) * | 2013-10-07 | 2015-04-20 | 株式会社ジェイテクト | Electric power-steering apparatus |
| JP6131208B2 (en) * | 2014-03-20 | 2017-05-17 | 本田技研工業株式会社 | Electric power steering device |
| CN109911004B (en) * | 2019-03-08 | 2022-05-24 | 华南理工大学 | Aligning control method and device of electric power steering device |
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