CN205819110U - A kind of road surface identifies device - Google Patents

Abstract

The utility model discloses a road surface recognition device, which comprises: a wheel speed sensor, which is installed on a car wheel, and is used to measure the wheel angular velocity; an acceleration sensor, which is installed on the car, and is used to measure the car acceleration; a pressure sensor, which is connected with the The wheel brake cylinder connection is used to measure the oil pressure of the wheel brake cylinder to obtain the braking torque; the ABS anti-lock braking system is used to provide different slip ratios when the car is braking; the controller is respectively connected to the The wheel speed sensor, acceleration sensor, pressure sensor, and ABS anti-lock braking system are connected, and the current adhesion coefficient is obtained by obtaining and measuring wheel angular acceleration, vehicle acceleration, and braking torque, so as to identify the current road surface.

Description

A road surface recognition device

technical field

The utility model belongs to the technical field of road surface recognition in vehicle engineering, in particular to a road surface recognition device.

Background technique

With the continuous development of automobile technology, people's requirements for vehicle performance are also getting higher and higher. In such a big environment, semi-active suspension technology, active suspension technology and ABS technology came into being. These new technologies have improved the comfort and safety of vehicles to a certain extent. If the type of road surface can be identified according to the driving status signal of the vehicle, the control logic in the above-mentioned new technology can be optimized to a large extent, thereby further improving the performance of the vehicle. Scholars at home and abroad have done a lot of research on road surface recognition methods used in real vehicle control systems, and have achieved certain results. Chinese patent CN102289674A and U.S. patent US4651290 both disclose a method of road surface recognition based on acceleration signals, which respectively perform frequency analysis and statistical analysis on acceleration signals, but this method requires a large number of tests to be used in different vehicles Calibration, and even for the same vehicle, load changes or suspension system changes (active suspension will automatically adjust the damping or stiffness parameters under different driving conditions) will affect the identification results. Moustapha Doumiati proposed a method of using Kalman filter to estimate the unevenness of the road surface at the ACC (American Control Conference), which can estimate the elevation of the road surface relatively simply, but this method does not have the adaptability to changes in vehicle system parameters .

Utility model content

The utility model designs and develops a road surface recognition device, which overcomes the defects of complicated structure and poor reliability of the existing road surface recognition technology recognition device.

The technical scheme provided by the utility model is:

A road surface recognition device, comprising

Wheel speed sensor, which is installed on the wheel of the car and used to measure the wheel angular velocity;

an acceleration sensor, which is installed on the vehicle and used to measure the acceleration of the vehicle;

A pressure sensor, which is connected to the wheel brake cylinder, is used to measure the oil pressure of the wheel brake cylinder, and then obtain the braking torque;

ABS anti-lock braking system, which is used to provide different slip ratios when the car is braking;

A controller is connected to the wheel speed sensor, the acceleration sensor, the pressure sensor and the ABS anti-lock braking system respectively.

Preferably, a display screen is also included to display the recognition result.

Preferably, a loudspeaker is also included to broadcast the recognition result by voice.

Preferably, the display screen is a touch screen.

Preferably, the wheel speed sensor is an electromagnetic induction wheel speed sensor.

Preferably, a vibrator prompter is also included.

The beneficial effects of the utility model are: the road surface recognition device provided by the utility model has the advantages of high recognition accuracy, fast speed, low hardware requirement, compact structure and high reliability.

Description of drawings

Fig. 1 is a structural schematic diagram of the road surface recognition device described in the present invention.

detailed description

The utility model will be described in further detail below in conjunction with the accompanying drawings, so that those skilled in the art can implement it by referring to the description.

As shown in FIG. 1 , the present invention provides a road recognition device, including a wheel speed sensor 110 , an acceleration sensor 120 , a pressure sensor 130 , an ABS anti-lock braking system 140 , a controller 150 , a display screen 160 and a speaker 170 .

By installing the wheel speed sensor 110 on the vehicle wheel to measure the wheel angular velocity, the angular acceleration is obtained after the difference, by installing the acceleration sensor 120 on the vehicle to measure the vehicle acceleration, and according to the acceleration, it can be calculated that the wheel is subject to the normal force from the ground; The pressure sensor 130 connected to the wheel brake cylinder measures the oil pressure of the wheel brake cylinder to obtain the braking torque. The ABS anti-lock braking system 140 is used to provide different slip ratios when braking the car.

The controller 150 is respectively connected with the wheel speed sensor 110, the acceleration sensor 120, the pressure sensor 130, and the ABS anti-lock braking system 140, and obtains the current adhesion coefficient by obtaining and measuring the wheel angular velocity, vehicle acceleration, and braking torque, so as to determine the current Identify the road surface.

The display screen 160 and the speaker 170 are also connected to the controller 150 , and the recognition result will be displayed on the display screen 160 and voiced by the speaker 170 .

The device also includes a vibrator prompter, which generates vibrations to remind the driver when entering the icy and snowy road, so as to drive carefully.

The braking process of the car from pure rolling to locking and slipping is a gradual process, which has gone through three stages: pure sliding, rolling while sliding and pure sliding. In order to evaluate the proportion of the slip component of the automobile wheel, the slip rate s is often used to express it.

When the slip rate is equal to zero, the lateral adhesion coefficient is the largest, the anti-skidding ability of the vehicle is the strongest, and the directional stability is the best when braking. The lateral adhesion coefficient decreases with the increase of the slip rate. When the wheel is completely locked and slipping, the lateral adhesion coefficient is zero, and the braking stability of the vehicle is the worst.

Based on the above theories, the ABS anti-lock braking system prevents the wheels from locking when the car brakes, and keeps the slip rate of the wheels within the range of the optimum slip rate to ensure good longitudinal and lateral contact between the wheels and the road. Adhesion, effectively prevent the car from skidding, tail flicking, loss of steering and other phenomena during braking, and improve the directional stability of the car during braking; when braking, the ABS system keeps the braking force within the best range, shortening the braking distance. This also reduces the severe friction between the tire and the ground and reduces tire wear.

Therefore, it is first necessary to calculate the optimum slip ratio, so as to provide a control basis for the ABS anti-lock braking system. The optimum slip ratio is related to the type of road surface, so it is necessary to identify the road surface.

According to the relationship between road surface adhesion coefficient and slip rate:

$\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}$

Where s is the slip ratio, μ(s) is the road surface adhesion coefficient, c ₁ , c ₂ , and c ₃ are the first reference coefficient, the second reference coefficient, and the third reference coefficient, respectively. Different road surfaces have different first reference coefficients, second reference coefficients, and third reference coefficients.

According to the above formula, when the road surface adhesion coefficient μ(s) is maximum, the corresponding slip rate s is the optimum slip rate s ₀ . As shown in Table 1, the values of the first reference coefficient, the second reference coefficient, the third reference coefficient and the optimum slip ratio of the six road surfaces.

Table 1

pavement c ₁ c ₂ c ₃ s ₀ Snow 0.195 94.13 0.0646 0.06 ice 0.050 306.39 0.001 0.031 dry asphalt 1.280 23.99 0.52 0.17 wet asphalt 0.857 33.82 0.35 0.131 dry pebbles 1.371 6.46 0.67 0.4 wet pebbles 0.4 33.71 0.12 0.147

According to the above formula and the vertical values of the first reference coefficient, the second reference coefficient, and the third reference coefficient, the function of the adhesion coefficient of the six road surfaces with respect to the slip ratio can be obtained.

Then calculate the average adhesion coefficient of the slip rate s in the interval [a,b]

$\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}<span\; class="notranslate">\; \&lsqb;</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; b</span>}}\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&rsqb;</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}}$

For the six road surfaces, the average adhesion coefficients of the slip rate s in the interval [a, b] are obtained respectively, which are respectively denoted as right Sort from smallest to largest, sequentially relabeled as

Then define the average adhesion coefficient identification interval of the six road surfaces, the average adhesion coefficient is The identification interval corresponding to the road surface is The average adhesion coefficient is The identification interval is By analogy, the average adhesion coefficient is The identification interval corresponding to the road surface is i=3,4,5; the average adhesion coefficient is The identification interval corresponding to the road surface is

As a preference, the interval [a, b] is [0.08, 0.11], and six road surfaces are calculated in this interval, and the average adhesion coefficients of snow, ice, dry asphalt, wet asphalt, dry cobblestone, and wet cobblestone pavement are respectively are 0.18, 0.05, 1.02, 0.8, 0.55, and 0.38. These six average adhesion coefficients are sorted from small to large, and they are the average adhesion coefficients corresponding to ice, snow, wet cobblestones, dry cobblestones, wet asphalt, and dry asphalt road surfaces. 0.05, 0.18, 0.38, 0.55, 0.8, 1.02, so the recognition intervals corresponding to ice, snow, wet cobblestones, dry cobblestones, wet asphalt, and dry asphalt roads are (0,0.0115], (0.0115,0.28], (0.28 ,0.465], (0.465,0.675], (0.675,0.91], (0.91,+∞).

According to the wheel equation:

$\mathrm{<span\; class="notranslate">\; J</span>}\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Z</span>}}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; ,</span>$

Among them, J is the moment of inertia of the wheel; is the angular deceleration of the wheel; μ ^* is the adhesion coefficient of the road surface; F _z is the normal force on the wheel from the ground; R is the rolling radius of the wheel; T _b is the braking torque of the wheel brake.

Angular deceleration of the wheel The angular velocity of the wheel measured by the wheel speed sensor is obtained after differential; the normal force _Fz received by the wheel from the ground can be obtained through the acceleration sensor and theoretical analysis; the braking torque _Tb of the wheel brake is measured by the force sensor The pressure of the brake wheel cylinder is converted into the braking force, and then multiplied by the distance from the point of action to the center of rotation.

After obtaining the above parameters, the adhesion coefficient of the current road surface can be calculated:

${\mathrm{<span\; class="notranslate">\; \&mu;</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; J</span>}\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Z</span>}}\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; .</span>$

When the vehicle is running, when the driver steps on the brake pedal, the car starts to brake, and the ABS anti-lock braking system works, so that the slip rate gradually increases from 0. When the slip rate is equal to a, the formula Get the adhesion coefficient of the current road surface and the current slip rate in As the slip rate continues to increase, the adhesion coefficient of the current road surface is collected every other sampling time Δt and the current slip rate Slip rate up to the Nth sampling point Then calculate the average adhesion coefficient of the car in the interval [a,b]

${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; ...</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>$

Final Judgment Draw Attachment Coefficient Which recognition interval it falls in, the road surface corresponding to the recognition interval is the recognition result.

Although the embodiment of the present utility model has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present utility model, and for those familiar with the art, Further modifications can be readily effected, so the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (6)

1. A road surface recognition device, characterized in that, comprising: Wheel speed sensor, which is installed on the wheel of the car and used to measure the wheel angular velocity; an acceleration sensor, which is installed on the vehicle and used to measure the acceleration of the vehicle; A pressure sensor, which is connected to the wheel brake cylinder, is used to measure the oil pressure of the wheel brake cylinder; ABS anti-lock braking system, which is used to provide different slip ratios when the car is braking; A controller is connected to the wheel speed sensor, the acceleration sensor, the pressure sensor and the ABS anti-lock braking system respectively. 2. The road surface recognition device according to claim 1, further comprising a display screen to display the recognition result. 3. The road surface recognition device according to claim 2, further comprising a loudspeaker for voice broadcasting of the recognition result. 4. The road recognition device according to claim 2, wherein the display screen is a touch screen. 5. The road surface recognition device according to claim 1, wherein the wheel speed sensor is an electromagnetic induction wheel speed sensor. 6. The road recognition device according to claim 1, further comprising a vibrator prompter.