KR20220055253A - Apparatus for compensating judder of motor driven power steering system and control method thereof - Google Patents

Abstract

Disclosed in the present invention are a device which compensates for judder of a motor driven power steering system and a control method thereof. The device which compensates for judder of a motor driven power steering system of the present invention comprises: a vibration sensing unit which senses the amount of vibration by receiving a column torque; a phase compensation unit which outputs a compensation torque by compensating a phase of an auxiliary torque, output from a MDPS control unit, based on a center frequency; a storage unit which stores a center frequency for phase compensation of the phase compensation unit; an output unit which selects the auxiliary torque, output from the MDPS control unit, and the compensation torque, output from the phase compensation unit, and outputs the torques as final auxiliary torques; and a compensation control unit which selects the output unit in response to an input of a brake signal, sets the center frequency to operate the phase compensation unit, moves the center frequency of the phase compensation unit when the amount of vibration of the column torque, detected by the vibration sensing unit, is greater than a set amount, and stores the center frequency in the storage unit when the amount of vibration is less than the set amount. According to the present invention, it is possible to offset vibration by driving the motor driven power steering system.

Description

A judder compensation device for electric power steering and a method for controlling the same

The present invention relates to a judder compensation device for an electric power steering system and a method for controlling the same, and more particularly, to an auxiliary torque output from an electric power steering system based on a vibration frequency caused by a judder phenomenon generated when a brake is operated. It relates to a judder compensating device for an electric power steering system that improves judder by compensating for the phase of the judder and a method for controlling the same.

In general, an electric power steering system (Motor Driven Power Steering; MDPS) uses an electric motor to provide auxiliary torque in a steering direction to make handling lighter.

Unlike a conventional hydraulic power steering (HPS), the electric power steering system can improve steering performance and steering feel by automatically controlling the operation of the electric motor according to the driving conditions of the vehicle.

In this case, the electric power steering apparatus includes a torque sensor for measuring the driver's steering torque input to the steering wheel, a steering angle sensor for measuring the steering angle of the steering wheel, and a vehicle speed sensor for measuring the vehicle speed to determine the driving condition of the vehicle.

On the other hand, if you step on the brake while driving, a judder phenomenon in which vibration and noise are generated from the steering wheel or the instrument panel may occur.

This judder phenomenon may cause vibration of the steering wheel and amplify the driver's psychological anxiety while driving the vehicle, thereby causing deterioration of vehicle driving stability.

In particular, when the vibration of the steering wheel is to be controlled by the driver's power without a separate assistance, the vibration of the steering wheel due to judder during high-speed turning driving braking inevitably further amplifies the driver's anxiety.

The background technology of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2015-0058839 (published on May 29, 2015, a method for preventing judder on a steering wheel and an electric steering device therefor).

When the judder phenomenon occurs as described above, as a method for reducing the judder phenomenon, the vibration can be canceled by sensing the judder frequency and applying the anti-phase compensation torque to drive the electric power steering device.

However, this method has a problem in that it is difficult to detect the correct judder frequency, and if the anti-phase compensation torque is not accurately canceled, the improvement effect of the judder phenomenon is reduced due to the adverse effect and may cause additional vibration.

The present invention has been devised to improve the above problems, and an object of the present invention according to one aspect is the phase of the auxiliary torque output from the electric power steering device based on the vibration frequency caused by the judder phenomenon generated when the brake is operated. To provide a judder compensating device for an electric power steering system that improves judder by compensating for the judder, and a method for controlling the same.

According to an aspect of the present invention, there is provided a judder compensator for an electric power steering system, comprising: a vibration sensing unit configured to receive a column torque and sense an amount of vibration; a phase compensator for compensating the phase with respect to the auxiliary torque output from the MDPS control unit based on the center frequency and outputting the compensated torque; a storage unit for storing a center frequency for phase compensation of the phase compensator; an output unit that selects the auxiliary torque output from the MDPS control unit and the compensation torque output from the phase compensator and outputs the final auxiliary torque; and selects the output unit according to the input of the brake signal, sets the center frequency to operate the phase compensator, and moves the center frequency of the phase compensator when the vibration amount of the column torque detected from the vibration sensing unit is greater than the set amount Compensation control unit for storing the center frequency in the storage unit when less than the amount; characterized in that it comprises a.

In the present invention, the vibration sensing unit includes: a filter unit for filtering column torque; and an accumulation unit for accumulating a difference value between the column torque filtered by the filter unit and the input column torque for a set time.

In the present invention, the filter unit is characterized in that it is either a low-pass filter or a moving average filter.

In the present invention, the filter unit filters the judder frequency by setting the cutoff frequency to a lower frequency than the judder frequency.

In the present invention, the phase compensator includes a full-pass filter that shifts the phase by 180 degrees without changing the magnitude of the auxiliary torque.

In the present invention, the compensation control unit is characterized in that when a brake signal is input, the compensation torque is selected to be output as the final auxiliary torque through the output unit.

In the present invention, the compensation control unit operates the phase compensator with the center frequency stored in the storage unit when a brake signal is input, and moves the center frequency so that the amount of vibration is less than the set amount when the amount of vibration from the phase compensator is greater than or equal to the set amount. It is characterized in that the central frequency is stored in the storage unit.

According to another aspect of the present invention, there is provided a method of controlling a judder compensator for an electric power steering apparatus, the method comprising: determining, by a compensation control unit, whether a brake signal is input; outputting the auxiliary torque output of the MDPS control unit as the final auxiliary torque by controlling the output unit when the brake signal is not input as a result of the compensation control unit determining whether the brake signal is input; Comparing the amount of vibration input from the vibration sensing unit with a set amount when the brake signal is input as a result of the compensation control unit determining whether a brake signal is input; Compensating the phase by operating the phase compensator with the center frequency stored in the storage unit when the compensation control unit compares the vibration amount with the set amount and when the vibration amount is less than the set amount; and the compensation control unit controlling the output unit to output the compensation torque output from the phase compensator as the final auxiliary torque.

The step of compensating for the phase in the present invention is characterized in that the phase is shifted by 180 degrees based on the center frequency without changing the magnitude of the auxiliary torque.

The present invention further comprises; when the compensation control unit compares the vibration amount with the set amount, and when the vibration amount is greater than or equal to the set amount, moving the center frequency so that the vibration amount is less than the set amount and storing the moved center frequency in the storage unit; do it with

According to an aspect of the present invention, a judder compensator for an electric power steering system and a control method therefor are provided by compensating for the phase of auxiliary torque output from the electric power steering system based on the vibration frequency caused by the judder phenomenon generated when a brake is operated, It is possible to not only improve the judder phenomenon while minimizing adverse effects, but also actively compensate for vehicle-dependent deviations.

1 is a block diagram illustrating a judder compensator of an electric power steering apparatus according to an embodiment of the present invention.
2 is a block diagram specifically illustrating a vibration sensing unit in a judder compensating device of an electric power steering apparatus according to an embodiment of the present invention.
3 is a flowchart illustrating a method of controlling a judder compensator of an electric power steering apparatus according to an embodiment of the present invention.

Hereinafter, a judder compensator for an electric power steering apparatus according to the present invention and a control method thereof will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user or operator. Therefore, definitions of these terms should be made based on the content throughout this specification.

1 is a block diagram illustrating a judder compensating device for an electric power steering system according to an embodiment of the present invention, and FIG. 2 is a detailed view of a vibration sensing unit in the judder compensating device for an electric power steering system according to an embodiment of the present invention. It is a block diagram shown by .

1 and 2, the judder compensator of the electric power steering apparatus according to an embodiment of the present invention includes a vibration sensing unit 20, a phase compensating unit 30, a storage unit 50, and an output unit. (60) and a compensation control unit 40 may be included.

The vibration sensing unit 20 may receive the column torque, sense the amount of vibration, and provide it to the compensation control unit 40 .

Here, the vibration sensing unit 20 may include a filter unit 22 and an accumulation unit 24 as shown in FIG. 2 .

The filter unit 22 may apply either a low-pass filter or a moving average filter, and sets a cutoff frequency to a lower frequency than the judder frequency to filter the judder frequency to detect the judder phenomenon.

The accumulator 24 may sense the amount of vibration by accumulating a difference value between the column torque filtered by the filter unit 22 and the input column torque for a set time.

The phase compensator 30 may compensate the phase with respect to the auxiliary torque output from the MDPS control unit 10 based on the center frequency to output the compensation torque.

Here, the MDPS control unit 10 may receive the vehicle speed, the steering angle, and the column torque, determine the driving condition of the vehicle, and provide the auxiliary torque in the steering direction of the driver.

In addition, the phase compensator 30 may include an all-pass filter that shifts the phase by 180 degrees without changing the magnitude of the auxiliary torque.

The storage unit 50 stores the center frequency for the phase compensation of the phase compensation unit 30, so that the rapid judder phenomenon can be reduced.

Since the judder phenomenon is caused by the fixation of the caliper or the deformation of the disk according to the vehicle, when the center frequency for phase compensation is set, it is not easily changed before mechanical deformation occurs.

Therefore, when the amount of vibration is generated less than a set amount while moving the center frequency for phase compensation, the center frequency is stored in the storage unit 50, so that the reduction effect can be increased by fast application during subsequent operation.

The output unit 60 may select the auxiliary torque output from the MDPS control unit 10 and the compensation torque output from the phase compensator 30 and output it as the final auxiliary torque.

The compensation control unit 40 selects the output unit 60 according to the input of the brake signal to output the auxiliary torque output from the MDPS control unit 10 or sets the compensation torque output from the phase compensation unit 30 as the final auxiliary torque. can be printed out.

That is, when the brake signal is not input, the auxiliary torque output from the MDPS control unit 10 is output, and when the brake signal is input, the compensation torque output from the phase compensator 30 is output to reduce the judder phenomenon. can

In addition, when a brake signal is input, the compensation control unit 40 sets the center frequency stored in the storage unit 50 and operates the phase compensator 30 to output the compensation torque.

At this time, the compensation control unit 40 moves the center frequency of the phase compensator 30 so that the amount of vibration is less than the set amount when the amount of vibration of the column torque sensed by the vibration detection unit 20 is equal to or greater than the set amount, and sets the moved center frequency. It may be stored in the storage unit 50 .

As described above, according to the judder compensator for the electric power steering apparatus according to the embodiment of the present invention, the phase of the auxiliary torque output from the electric power steering apparatus is adjusted based on the vibration frequency due to the judder phenomenon generated when the brake is operated. By compensating, it is possible to not only improve the judder phenomenon while minimizing adverse effects, but also actively compensate for vehicle-dependent deviations.

3 is a flowchart illustrating a method of controlling a judder compensator of an electric power steering apparatus according to an embodiment of the present invention.

As shown in FIG. 3 , in the control method of the judder compensation device of the electric power steering apparatus according to an embodiment of the present invention, first, the compensation control unit 40 determines whether a brake signal is input ( S10 ).

When it is determined whether a brake signal is input in step S10 and the brake signal is not input, the compensation control unit 40 switches so that the auxiliary torque output from the MDPS control unit 10 through the output unit 60 is output as the final auxiliary torque. do (S20).

When it is determined whether a brake signal is input in step S10 and the brake signal is input, the compensation control unit 40 compares the amount of vibration input from the vibration sensing unit 20 with a set amount ( S30 ).

Here, the amount of vibration receives the column torque from the vibration detecting unit 20 and accumulates and detects the difference between the column torque filtered through the low-pass filter or the moving average filter and the unfiltered column torque for a set time. can

After comparing the vibration amount and the set amount in step S30, if the vibration amount is less than the set amount, the compensation control unit 40 compensates the phase by applying the center frequency stored in the storage unit 50 to the phase compensating unit 30 and operating it. (S50).

Here, the phase compensator 30 may compensate the phase with respect to the auxiliary torque output from the MDPS control unit 10 based on the center frequency to output the compensation torque.

That is, the phase compensator 30 can compensate by shifting the phase 180 degrees based on the center frequency without changing the magnitude of the auxiliary torque through an all-pass filter.

On the other hand, if the vibration amount and the set amount are compared in step S30 and the vibration amount is greater than or equal to the set amount, the compensation control unit 40 moves the center frequency so that the vibration amount is less than the set amount and stores the moved center frequency in the storage unit 50 Save (S40).

Thereafter, the compensation control unit 40 compensates the phase by applying the center frequency to the phase compensator 30 and operating it (S50).

After compensating the phase by operating the phase compensator 30 in this way, the compensation control unit 40 switches the compensation torque output from the phase compensator 30 through the output unit 60 to be output as the final auxiliary torque ( S60).

As described above, according to the control method of the judder compensator of the electric power steering apparatus according to the embodiment of the present invention, the auxiliary torque output from the electric power steering apparatus based on the vibration frequency due to the judder phenomenon generated when the brake is operated By compensating the phase of , it is possible to not only improve the judder phenomenon while minimizing the adverse effect, but also actively compensate for vehicle-dependent deviations.

Implementations described herein may be implemented in, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Although discussed only in the context of a single form of implementation (eg, discussed only as a method), implementations of the discussed features may also be implemented in other forms (eg, as an apparatus or program). The apparatus may be implemented in suitable hardware, software and firmware, and the like. A method may be implemented in an apparatus such as, for example, a processor, which generally refers to a computer, a microprocessor, a processing device, including an integrated circuit or programmable logic device, or the like. Processors also include communication devices such as computers, cell phones, portable/personal digital assistants (“PDAs”) and other devices that facilitate communication of information between end-users.

Although the present invention has been described with reference to the embodiment shown in the drawings, this is merely an example, and those skilled in the art to which various modifications and equivalent other embodiments are possible. will understand

Therefore, the true technical protection scope of the present invention should be defined by the following claims.

10: MDPS control unit 20: vibration sensing unit
22: filter unit 24: accumulation unit
30: phase compensator 40; compensation control unit
50: storage unit 60: output unit

Claims (10)

a vibration sensing unit that receives column torque and senses an amount of vibration;
a phase compensator for compensating the phase with respect to the auxiliary torque output from the MDPS control unit based on the center frequency and outputting the compensated torque;
a storage unit for storing the center frequency for phase compensation of the phase compensator;
an output unit for selecting the auxiliary torque output from the MDPS control unit and the compensation torque output from the phase compensator and outputting the selected auxiliary torque as a final auxiliary torque; and
Selects the output unit according to the input of the brake signal, sets the center frequency to operate the phase compensator, and when the vibration amount of the column torque detected by the vibration sensing unit is greater than or equal to a set amount, the center frequency of the phase compensator is set and a compensation control unit for moving and storing the center frequency in the storage unit when the vibration amount is less than the set amount.
According to claim 1, wherein the vibration sensing unit,
a filter unit filtering the column torque; and
and an accumulator for accumulating a difference value between the column torque filtered by the filter unit and the input column torque for a set time.
The judder compensator of claim 2, wherein the filter unit is any one of a low-pass filter and a moving average filter.
The judder compensator of claim 3, wherein the filter unit filters the judder frequency by setting a cut-off frequency to a lower frequency than the judder frequency.
The judder compensator of claim 1, wherein the phase compensator comprises a full-pass filter that shifts the phase by 180 degrees without changing the magnitude of the auxiliary torque.
The judder compensator of claim 1, wherein the compensation control unit selects the compensation torque to be output as the final auxiliary torque through the output unit when the brake signal is input.
The method of claim 1, wherein the compensation control unit operates the phase compensator with the center frequency stored in the storage unit when the break signal is input, and when the vibration amount from the phase compensator is equal to or greater than the set amount, the vibration amount Judder compensator for electric power steering system, characterized in that by moving the center frequency to be less than the set amount and storing the moved center frequency in the storage unit.
determining, by the compensation control unit, whether a brake signal is input;
outputting the auxiliary torque output of the MDPS control unit as final auxiliary torque by controlling the output unit when the brake signal is not input as a result of the compensation control unit determining whether the brake signal is input;
comparing the amount of vibration input from the vibration sensing unit with a set amount when the brake signal is input as a result of the compensation control unit determining whether the brake signal is input;
compensating the phase by operating the phase compensator with the center frequency stored in the storage unit when the compensation control unit compares the vibration amount with the set amount and when the vibration amount is less than the set amount; and
and outputting the compensation torque output from the phase compensator as the final auxiliary torque by the compensation control unit controlling the output unit.
The method according to claim 8, wherein the step of compensating for the phase shifts the phase by 180 degrees based on the center frequency without changing the magnitude of the auxiliary torque.
The method according to claim 8, wherein the compensation control unit compares the vibration amount with the set amount and, when the vibration amount is equal to or greater than the set amount, moves the center frequency so that the vibration amount is less than the set amount and sets the moved center frequency to the Storing in the storage unit; Control method of the judder compensation device of the electric power steering system, characterized in that it further comprises.

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