KR102325644B1 - Brake System for a Vehicle Rolling Tire by the Excitation of Normal Vibration - Google Patents

Abstract

A braking device using vertical vibration excitation in a tire of a traveling vehicle is provided. The braking device according to the embodiment of the present invention effectively increases the kinetic friction force when the tire slips through a new braking method that applies vibration to the wheel to compensate for the AC vertical drag acting between the tire and the road surface of the wheel, thereby lowering the braking force and increasing the braking distance. Accordingly, it is possible to significantly reduce the accident rate due to the slip of the vehicle, and it is possible to enable much safer driving through interaction with the existing brake system.

Description

Brake System for a Vehicle Rolling Tire by the Excitation of Normal Vibration

The present invention relates to a vehicle braking system, and more particularly, to a vehicle braking system for improving braking force of a vehicle on a slippery road surface.

In a wheeled vehicle traveling on a slippery road surface, such as a snowy field, ice sheet, frosty road, muddy or rain-soaked block road, if a slip occurs during braking, the braking force is reduced due to a very small dynamic coefficient of friction between the wheel and the contact surface. It becomes very small and the braking distance becomes long. In addition, even if the braking force provided by the brake system of each wheel is the same, the slip amount of all wheels is slightly different on the contact road surface, and accordingly, it is sensitive to even a slight steering change, so it is easy to become uncontrollable, leading to an accident. poses a possible risk.

To prevent this, a method of using an increase in the vertical drag component according to a small contact area by mounting a snow-only chain or a snow tire having a thick groove on the tire has been widely used.

However, there are problems in that it is inconvenient to install or replace each time on snow or ice, must be operated only at a very low speed, and cannot effectively cope with the slipping of the vehicle.

In order to shorten the braking distance on a slippery surface or during sudden braking, a method of increasing braking force by introducing an electronic ABS (Anti-lock Brake System) to the vehicle wheel and providing traction force more than 10 times per second during sudden braking is widely used. have. However, even in very slippery road conditions such as on snow, ice, sand, etc., even ABS does not help with accurate and fast braking.

The present invention has been devised to solve the above problems, and an object of the present invention is to improve the braking force of a vehicle through a new braking method in which vibration is applied to the wheels to compensate for the alternating vertical drag acting between the tire and the road surface. To provide a braking device and method capable of

According to an embodiment of the present invention for achieving the above object, a braking device includes: a first vibrator for generating vibration and applying the generated vibration to a wheel; and a controller for controlling the first vibrator to generate vibration during braking.

In addition, the first vibrator may apply vibration for compensating for alternating vertical drag acting between the tire of the wheel and the road surface.

In addition, the first vibrator may be installed in the housing of the shaft on which the wheel is mounted.

In addition, the vibration generated by the first vibrator may have a frequency band of 260 Hz to 500 Hz.

Also, the vibration generated by the first vibrator may have a bandwidth of 120 Hz or less.

And, the vibration generated by the first vibrator may be a single frequency vibration or a multi-frequency vibration.

In addition, further comprising a first sensor for measuring the moving speed of the vehicle, the controller may control the vibration generated by the first vibrator based on the moving speed of the vehicle measured by the first sensor.

In addition, the braking device according to an embodiment of the present invention may further include a second vibrator that applies vibration to cancel the propagation of the vibration generated in the first vibrator to the vehicle side.

In addition, the braking device according to an embodiment of the present invention may further include a third vibrator that applies vibration to cancel the propagation of the vibration generated by the first vibrator to the vehicle side.

In addition, the first vibrator may be installed on one side of the housing, and the second vibrator may be installed on one side of the housing at a position closer to the vehicle side than the first vibrator.

Also, the first vibrator may be installed on one side of the housing, and the third vibrator may be installed on the other side of the housing opposite to one side where the first vibrator is installed.

In addition, the braking device according to an embodiment of the present invention further includes a second sensor for measuring vibration propagated in the housing, wherein the controller includes a second vibrator and a second vibrator based on the vibration measured by the second sensor. Vibration generated by the third vibrator can be controlled.

Also, the wheel may be a wheel of a vehicle.

Meanwhile, according to another embodiment of the present invention, a braking method includes: controlling to generate vibration when a wheel is braked; and applying the generated vibration to the wheel.

As described above, according to the embodiments of the present invention, the kinetic friction force is effectively increased when the tire slips through a new braking method that applies vibration to the wheel to compensate for the alternating vertical drag acting between the tire and the road surface of the wheel. This can solve the problems of decreasing braking power and increasing braking distance.

According to embodiments of the present invention, it is possible to significantly reduce the incidence of accidents due to vehicle slipping, and to enable much safer driving through interaction with the existing brake system.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view provided for the explanation of the frictional force that occurs between a tire and a road surface;
2 is a view provided for conceptual explanation of a braking device according to an embodiment of the present invention;
Figure 3 is an example showing the reinforcement of the overall friction force through the dynamic friction force compensation,
4 is a table showing the coefficient of friction;
5 is a view showing the dynamic frictional force acting between the automobile tire and the road surface, and,
6 is a detailed configuration diagram of the braking device according to the embodiment of the present invention shown in FIG. 2 .

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In an embodiment of the present invention, braking performance is improved through vertical vibration excitation in a tire of a traveling vehicle. Specifically, an embodiment of the present invention proposes a method of making the braking force on a slippery surface similar to that of a non-slip road surface by applying a vertical vibration in a mid-high frequency band that the occupant does not feel to the vehicle wheels.

According to the vibration excitation of a relatively high frequency, an additional dynamic vertical force other than the dynamic load according to the dynamic movement of the vehicle's own weight is generated to generate a tangential resistance force of the tire, and in addition to the existing small kinetic friction force on the sliding ground surface, the tire and It creates a resistance that increases the traction between the road surfaces. That is, in the embodiment of the present invention, vertical vibration between the tire and the contact surface is used to improve braking performance.

1 is a view provided for explanation of frictional force generated between a tire and a road surface. The normal drag force acting between the road surface and the tire can be divided into direct current and alternating current components, which act as a constant component and a variable component with respect to the time of the friction force, that is, a dynamic friction force, respectively.

는 F/N으로 주어지며, 전체 마찰력 F(t)는 다음의 식 (1)과 같이 일정한 평균 성분과 시간에 따라 변동하는 성분으로 각각 표현할 수 있다:Specifically, as shown in FIG. 1, when a smooth road surface and a vehicle tire come into contact with each other and start a relative sliding motion, the frictional force generated on the contact surface appears as a constant average component with respect to time and a component that varies with time. do. The time-varying action force is inherent in the motion mechanism itself, such as contact vibration or reciprocating excitation or periodic excitation due to surface roughness given in magnitude relative to the speed of the vehicle. When the average normal force is N and the average friction force is F, the average kinetic friction coefficient

is given as F/N, and the total friction force F(t) can be expressed as a constant average component and a time-varying component, respectively, as shown in Equation (1):

(1)

(One)

로, 교류 성분은 순간 동마찰계수인

로 나타낸 일정한 상수의 마찰계수 값에 의해 결정된다. 한편, 일반 포장도로에서는

이므로, 식 (1)의 두번째 항은 무시가 가능하다. 또한, 눈밭이나 빙판, 서리 내린 길, 진흙탕 길 등과 같이 미끄러운 노면의 경우, 내재하는 왕복 운동형이나 주기적인 가진이 없으며, 또 조도가 매우 작으므로 표면 조도에 기인한 접촉 진동도 매우 작아서, 식 (1)의 두번째 항인 동적인 성분은 역시 무시할 수 있다. 따라서, 아래의 식 (2)와 같이 차량 전체의 무게에 해당하는 수직항력 N₀을 사용해 간략히 쓸 수 있다:For the normal drag in Equation (1), when the constant component N ₀ with respect to time is considered as direct current (DC) and the dynamic component f _N (t) as alternating current (AC), the direct current component is the coefficient of kinetic friction.

, the AC component is the instantaneous coefficient of kinetic friction

It is determined by the constant constant friction coefficient value denoted by . On the other hand, on the general paved road

Therefore, the second term in Equation (1) can be ignored. In addition, in the case of a slippery road surface such as a snowy field, ice sheet, frosty road, or muddy road, there is no inherent reciprocating motion or periodic excitation, and since the roughness is very small, the contact vibration due to the surface roughness is also very small, The dynamic component, which is the second term in 1), is also negligible. Therefore, it can be written simply using _{the normal force N 0} corresponding to the weight of the entire vehicle as shown in Equation (2) below:

(2)

(2)

In the case of the above-mentioned slippery road surface, the average coefficient of dynamic friction between the tire and the road surface is about 0.02-0.05 on an icy or frosty road, and about 0.1-0.15 on a snowy road, when the slip ratio λ is 25% or more. This is a very small size compared to the average dynamic friction coefficient of about 0.4-0.9 that occurs on a general asphalt or concrete road surface, which means that it can cause a big problem in braking performance when braking a driving vehicle. Here, the slip ratio is given by the following Equation (3) in SAE J670, when V is the dependence of the vehicle, Ω is the wheel rotation speed, and R is the radius of the wheel at the center of the wheel in the no-load state without grounding:

(3)

(3)

If equation (2) can be compensated for by increasing the static weight or dynamic friction component, the total friction force increases as in equation (1), so that even on a slippery road surface, it is the same as braking on a general asphalt or concrete road surface, or less slippery. can be Not usually possible to the static weight is increasing dramatically, the way that artificial exchange vertical force on the tire from the outside will remain, if such exchange type or swing type, ie vibrations external force (external vibratory excitation) f _v is given, below, It would be possible to increase the magnitude of the dynamic friction force as in equation (4):

(4)

(4)

는 이제 요동형 동마찰계수(oscillatory kinetic friction coefficient)라고 부를 수 있다.here,

can now be called the oscillatory kinetic friction coefficient.

An excitation system for obtaining such additional dynamic frictional force can be implemented as shown in FIG. 2 . 2 is a diagram provided to explain the concept of a braking device according to an embodiment of the present invention.

As shown in FIG. 2 , the braking device according to the embodiment of the present invention is configured to include an actuator-1 110 , an actuator-2 120 , and an actuator-3 130 . . The vibrators 110 , 120 , and 130 are installed in the housing 30 of the drive shaft or axle shaft 20 on which the wheel 10 is mounted.

The vibrator-1 110 is a vibrator that applies vibration to the wheel 10 to compensate for alternating vertical drag acting between the tire of the wheel 10 and the road surface.

The vibration generated by the vibrator-1 110 and transmitted to the tire of the wheel 10 increases the alternating current component of the normal drag, thereby strengthening the dynamic friction force, thereby increasing the friction force between the tire and the road surface.

The vibrator-2,3 (120,130) is a vibrator that applies vibration to cancel the vibration generated from the vibrator-1(110) from propagating to the vehicle side rather than the wheel 10, specifically, to other parts inside the vehicle body. admit.

The vibrator-2 (120) is installed on the side of the vibrator-1 (110), and is installed at a position closer to the vehicle side than the vibrator-1 (110). That is, as shown in FIG. 2 , the vibrator-1 110 and the vibrator-2 120 are installed adjacent to one side of the housing 30 , the vibrator-1 110 is the wheel 30 . At a position close to , the vibrator-2 120 is installed at a position close to the vehicle, respectively.

The vibrator-3 130 is installed on the other side of the housing 30 opposite to one side of the housing 30 in which the vibrator-1 110 is installed.

3 is an example showing reinforcement of overall frictional force through dynamic frictional force compensation. When the dynamic component of the friction force is strengthened, the energy of the friction force is directly related to the square of the envelope of the overall shape, so it is possible to predict the gain and the prediction of the total friction force according to the strengthening of the dynamic friction force component.

Fig. 3 (a) shows a state in which the dynamic friction force is compensated through the friction force generated on the tire and the slippery road surface and the vibration of the vibrator and its envelope, and Fig. 3 (b) shows the effective value of the friction force, respectively.

"는 타이어-빙판 사이의 마찰력을, "

"는 가진기의 진동으로 생긴 요동형 저항에 의한 마찰력 성분을, "

"는 요동형 저항에 의한 마찰력의 envelope을, "

"은 경질고무-유리(타이어-빙판을 모사) 간 마찰력의 실효값을, "

"은 요동형 저항에 의한 마찰력의 envelope에 의한 동적 마찰력 성분이 기존의 경질고무-유리 간의 동마찰력에 보상된 최종적인 동마찰력의 실효값을 각각 나타내었다.In Fig. 2 "

"is the friction force between the tire and ice,"

" is the frictional force component caused by the oscillating resistance caused by the vibration of the vibrator, "

" is the envelope of the friction force by the oscillating resistance, "

"is the effective value of friction force between hard rubber-glass (imitation of tire-ice plate),"

" shows the effective value of the final dynamic friction force in which the dynamic friction force component by the envelope of the friction force caused by the oscillation type resistance is compensated for the existing hard rubber-glass dynamic friction force, respectively.

3 shows the experimental results of how the dynamic frictional force is increased by this method when rubbing hard rubber on a slippery surface such as glass (simulating friction between a slippery road surface and a tire). The hard rubber used in the experiment has a Shore hardness of 73. Considering that the rubber used for the tire tread has a Shore hardness of about 65-70, it can be said to be a similar material.

In addition, as shown in the table of FIG. 4 , since the coefficient of dynamic friction between ice and rubber is known to be about 0.15, the result of FIG. 3 showing the case between hard rubber and clean glass surface shows the coefficient of dynamic friction between the frozen road surface and the running tire. It can be said that the case is very similar to

In contrast, the coefficient of dynamic friction between the tire and the dry general asphalt road surface is a very large value of 0.5-0.8. 5 schematically shows when this situation is applied to an actual vehicle. The left side of FIG. 5 shows the dynamic frictional force acting between the car tire and the road surface running on a slippery road surface, and the right side of FIG. 5 shows the principle of FIG. 3 using the vertical vibration of an external input vibrator connected to the wheel under the same conditions. showed the kinetic friction force compensated by

As a simple example, a method of applying a sine wave vibration having a constant amplitude to the axle can be considered, but when the vibration frequency is low, the positive phase and negative phase of the vibration are It is well differentiated compared to the speed, so it can be said that there is no overall benefit if you take the average for a certain period of time. For example, a vehicle traveling at 20 kph per hour or sliding at a speed of 5.6 m per second moves at 5.6 m per second. There is no great gain in frictional force generation. In addition, when an external excitation for compensating for frictional force is given at a low frequency, the occupant feels vibration in a band of about 35-500 Hz. On the other hand, it can also be noted that humans, on average, feel the touch vibration most sensitively to vibrations of about 200-250Hz.

Although excitation below 250Hz can be used, if residual vibration is transmitted to the chassis and body, it can become a new vibration-noise source if it matches the structure of various parts, body panel, and resonance of the internal space. It should be noted. In addition, since structural resonance of the tire itself appears prominently in a band of about 80-260 Hz, excitation using this band is likely to have a great effect on driving stability and ride comfort. It is possible to use a frequency of about 500 Hz or more that humans do not feel, but as the excitation frequency increases, the efficiency of the energy input to the vibrator deteriorates, and thus the controllable excitation force becomes small. you can say no In addition, since the central peak of the noise, which is the air and the structural air by the tire structure, is usually in the 700-1300 Hz band, the excitation of about 600 Hz or more can be said to be negative in terms of noise-vibration.

Therefore, taking into account the above, it is recommended to use a frequency of about 300-400 Hz or higher when using the vibration damper together, but it can be said that any frequency between 260-500 Hz can be used in the case of cancellation control. On the other hand, in terms of vibration of the body, suspension, other chassis and tires, the 260-500 Hz band corresponds to the mid-high frequency, which means that there are very many related vibration modes.

Therefore, it is difficult to avoid a large resonance of a specific part even with any pure tone excitation. On the other hand, in the case of excitation of several different frequencies with almost the same energy level or band excitation having a specific bandwidth, the negative effect is reduced due to the effect of mutual interference between several resonance modes (smearing effect). ). Considering the energy efficiency of excitation, narrow-band excitation is more advantageous than broadband excitation. can be seen to be appropriate.

As such, in the case of multi-frequency excitation, which is considered to be mid-high frequency in terms of vibration, the energy provided by the normal force is the envelope or root-mean-square (RMS) of the entire input waveform over time rather than individual vibration waveforms. closely related The envelope of an oscillating signal is expressed as a smooth sequencing of the largest amplitude, and its temporal fluctuation is usually very slow. In the case of mid-frequency and high-frequency oscillations, especially in the case of complex multi-frequency oscillations in these frequency bands, the amplitude of generating the corresponding energy depends on the size of the envelope representing the fluctuation of the entire waveform, not the individual signals composing the entire waveform. It is a well-known fact in language communication and in understanding the size and characteristics of the sound produced by a musical instrument. In the case of a signal in which simple harmonic oscillation is successively superimposed (~e ^jωt ), it can be expressed as Equation (5) below:

(5)

(5)

), ω는 각주파수(angular frequency; rad/s), c_ph는 파동의 위상속도(phase velocity), f(k)는 초기 변위에 대한 푸리에 변환값(Fourier transform)을 나타낸다. 이러한 복합 요동을 총괄적으로 나타내는 해는 수학적으로 정상위상법 (method of stationary phase)에 의해 아래의 식 (6)과 같이 얻어진다:Here, k is a wave number;

), ω are angular frequency (rad/s), c _ph is the phase velocity of the wave, and f(k) is the Fourier transform value for the initial displacement. A solution representing these complex fluctuations as a whole is mathematically obtained as Equation (6) below by the method of stationary phase:

(6)

(6)

According to the steady-state condition, the following equation (7) becomes:

(7)

(7)

Here, c _g means the group velocity at which energy propagates. The physical meaning of equations (6) and (7) is _{that the narrowband fluctuation composed of multiple frequencies centered at ω 0} as the center frequency has an amplitude varying with time as a whole, and the change in amplitude due to each fluctuation within the band Rather, it indicates that the overall amplitude is determined according to the group velocity variation in the center frequency representing the entire band, that is, the envelope of the waveform. Since the group velocity corresponds to the propagation velocity of energy, the envelope expression for the total bandwidth fluctuation given in Equation (6) means an equivalent amplitude that can be expressed as energy by squaring.

In the processing of real data, a representative signal processing technique for extracting the signal envelope is expressed as the size of the analytic signal obtained as a result of the Hilbert transform as shown in Equation (8-9) below:

(8)

(8)

(9a,b)

(9a,b)

는 x(t)의 Hilbert transform 결과이며, A(t)와 θ(t)는 각각 해석적 신호의 크기와 위상으로, 물리적인 의미로는 x(t)의 envelope와 순간 위상을 의미한다. 위의 식 (8-9)에서, 신호

은 해당하는 수직력 혹은 가속도와 관련된 변수라고 생각할 수 있다. 마찰력은 수직항력에 비례하므로, 이러한 요동에 의해 생기는 마찰력은 진동 가속도 envelop에 비례하게 된다. 또, 물리계의 에너지 값은 관련된 계측 물리변수의 제곱에 비례하므로, 식 (9)에 의하면 특정 시간에서 envelope의 크기 A는 신호의 파워, 즉 에너지와 직접 관련된다. 이 에너지는 envelope의 해석으로부터 얻어지는 군속도(group velocity)를 따라 전달된다.Here, z(t) is the analytic signal of x(t),

is the result of the Hilbert transform of x(t), and A(t) and θ(t) are the magnitude and phase of the analytic signal, respectively, and in a physical sense, the envelope and instantaneous phase of x(t). In the above equation (8-9), the signal

can be thought of as a variable related to the corresponding normal force or acceleration. Since the frictional force is proportional to the normal force, the frictional force generated by this fluctuation is proportional to the vibrational acceleration envelope. Also, since the energy value of the physical system is proportional to the square of the related measured physical variable, according to Equation (9), the size A of the envelope at a specific time is directly related to the power of the signal, that is, the energy. This energy is transferred along the group velocity obtained from the analysis of the envelope.

Therefore, by using the vibration acceleration envelope, it is possible to know the magnitude and transmission pattern of the energy of the oscillating signal, and by the same principle, it is possible to predict or evaluate the frictional force increased by the application of the vertical vibration. In this way, when the complex vibration of mid-high frequency is applied to the tire grounded to the ground, an additional frictional force is generated in the existing kinetic friction given by the existing ground, tire material, and relative speed.

6 is a detailed configuration diagram of the braking device according to the embodiment of the present invention shown in FIG. 2 . As shown in FIG. 6 , the braking device according to an embodiment of the present invention includes vibrators 110 , 120 , and 130 , a velocity sensor 140 , a force sensor 150 , and a vibration sensor. ) 160 , the vibrator driving unit 170 and the power supply 180 are configured.

The vibrators 110 , 120 , and 130 have been described in detail with reference to FIG. 2 , so a description thereof will be omitted here.

The speed sensor 140 measures the moving speed of the vehicle, the force sensor 150 measures the magnitude of vibration applied by the vibrator-1 110 , and the vibration sensor 160 is equipped with the wheel 10 . Measure the vibration in the housing 30 of the drive shaft or axle shaft 20 . Measurement results by the sensors 140 , 150 , and 160 are transmitted to the vibrator driving unit 170 .

The vibrator driving unit 170 includes a data memory 171 , a controller 172 , and an amplifier 173 .

Measurement results by the sensors 140 , 150 , and 160 are stored as data in the data memory 171 . The controller 172 generates a control signal for controlling the vibrators 110 , 120 , 130 based on the data stored in the data memory 171 , amplifies it through the amplifier 173 and applies it to the vibrators 110 , 120 , 130 .

Specifically, the controller 172 generates a control signal for generating a vibration that causes the speed control corresponding to the vehicle speed measured by the speed sensor 140 to be made when the sliding motion of the tire occurs, thereby generating the vibrator-1 ( 110) is controlled.

The excitation signal of the exciter-1 110 is suitable for single-frequency narrowband excitation or multi-frequency excitation having a bandwidth smaller than 100-120 Hz within the 260-500 Hz frequency band, the specific excitation value is determined by the speed of the vehicle .

At this time, the controller 172 recognizes the vibration state of the vibrator-1 110 measured by the force sensor 150, and feedback control is possible.

In addition, the controller 172 generates control signals for generating vibration capable of canceling the vibration in the housing 30 measured by the vibration sensor 160 , and the vibrator-2 120 and the vibrator- 3 (130) is controlled.

The power supply 180 supplies power necessary to the vibrators 110 , 120 , 130 , the sensors 140 , 150 , 160 , and the vibrator driving unit 170 .

Up to now, a preferred embodiment of a braking device using vertical vibration excitation in a tire of a traveling vehicle has been described in detail.

In the above embodiment, the housing 30 of the shaft 20 on which the wheels 10, which are positions at which the vibrators 110, 120, and 130 are installed, are mounted are merely exemplary. Of course, it is possible to position the vibrators 110 , 120 , and 130 at different positions according to the structure, shape and type of the vehicle dynamometer.

In addition, in the above embodiment, the vibrator-2 120 and the vibrator-3 130 correspond to an optional configuration. Even when a braking device is implemented by excluding at least one of them, the technical spirit of the present invention may be applied.

Furthermore, in the case of an electric vehicle, it goes without saying that the technical idea of the present invention can be applied even in the case of controlling the excitation and vibration at the position where the electric motor is attached. Furthermore, the technical idea of the present invention can be applied to other drive systems other than the vehicle.

In addition, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention as claimed in the claims Various modifications are possible by those of ordinary skill in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

10 : wheel
20: Axle (drive shaft or axle shaft)
30: housing
110: Actuator-1
120: exciter-2
130: exciter-3
140: velocity sensor (Velocity sensor)
150: force sensor
160: vibration sensor (Vibrometer)
170: exciter driving unit
171: data memory
172: controller
173: amplifier
180: power supply

Claims (14)

a first vibrator that generates vibration and applies the generated vibration to the wheel;
a controller for controlling the first vibrator to generate vibration upon braking; and
Including;
The first vibrator,
On one side of the housing, it is installed at a position closer to the wheel than the second vibrator,
The second vibrator,
A braking device, characterized in that it is installed at one side of the housing, closer to the vehicle body side than the first vibrator.
The method according to claim 1,
The first vibrator,
A braking system, characterized in that it applies vibration to compensate for the alternating vertical drag acting between the tire of the wheel and the road surface.
The method according to claim 1,
The first vibrator,
A brake device, characterized in that it is installed in the housing of the axle on which the wheel is mounted.
4. The method according to claim 3,
The vibration generated by the first vibrator is,
A braking device, characterized in that the frequency band is within 260 Hz to 500 Hz.
5. The method according to claim 4,
The vibration generated by the first vibrator is,
A braking device, characterized in that the bandwidth is within 120 Hz.
6. The method of claim 5,
The vibration generated by the first vibrator is,
A braking device, characterized in that it is a single-frequency vibration or a multi-frequency vibration.
The method according to claim 1,
A first sensor for measuring the moving speed of the vehicle; further comprising,
The controller is
A braking device, characterized in that the vibration generated by the first vibrator is controlled based on the moving speed of the vehicle measured by the first sensor.
delete The method according to claim 1,
The braking device further comprising: a third vibrator that applies vibration to cancel the vibration generated by the first vibrator from propagating toward the vehicle body.
delete 10. The method of claim 9,
The third vibrator,
A braking device, characterized in that the first vibrator is installed on the other side of the housing opposite to the installed side.
The method according to claim 1,
Further comprising; a second sensor for measuring the vibration propagated in the housing;
The controller is
A braking device characterized in that the vibration generated by the second vibrator and the third vibrator is controlled based on the vibration measured by the second sensor.
The method according to claim 1,
the wheel,
A braking device, characterized in that it is a wheel of a vehicle.
delete

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