KR19980084285A - Vehicle safety control device - Google Patents

Abstract

The present invention relates to a vehicle safety control device capable of independently controlling brake torque by accurately calculating vehicle side slip angle and target vehicle side slip angle through an equation based on vehicle dynamics. The road surface friction coefficient is obtained by using the sensor signals measured by the sensor, steering wheel angle sensor, yaw rate sensor, lateral acceleration sensor, and brake pressure sensor.The road friction coefficient is used to calculate the lateral tire friction force and the longitudinal tire friction force. The tire slip angle, the side slip angle of the vehicle, and the lateral vehicle speed are estimated by using the sensor signals measured by the sensors and the lateral / longitudinal tire friction force, the target rate is obtained by referring to the vehicle body rate, and measured by each sensor. The target vehicle using the measured sensor signal and lateral / longitudinal tire friction and target rate After the room slip angle is obtained, the body rate, the target rate, the side slip angle of the vehicle and the side slip angle of the target vehicle are compared with each other so that the body rate follows the target rate and the vehicle side slip angle follows the target vehicle side slip angle. By obtaining a signal and operating the hydraulic modulator according to the control signal, the brake torque can be independently controlled to achieve driving safety of the vehicle.

Description

Vehicle safety control device

The present invention relates to a vehicle safety control device capable of independently calculating brake side torques of four wheels by accurately calculating vehicle side slip angles and target vehicle side slip angles through simple equations based on vehicle dynamics.

Generally, the driving safety control device related to braking and driving of a vehicle is a technology in which a wheel slip prevention device and a driving force control device are further developed.

This driving safety control device independently of the brakes of the four wheels as needed, even if the driver does not step on the brake pedal when the electronic controller mounted on the vehicle determines whether the vehicle is running safely and tends to deviate from the driving route. To drive the vehicle safely along the travel route.

As shown in FIG. 1, the driving safety apparatus of the related art vehicle includes wheel speed sensors 11 to 14 that measure the speeds of the front, rear, left and right four wheels 1 to 4, and each of the wheels 1 to 4. Drum or disc brakes 21 to 24 installed, brake pressure sensor 5 for measuring the hydraulic pressure of the brake master cylinder, wheel cylinders or disc brakes of the drum brake via hydraulic pipelines 31 to 34 connected to the brake master cylinder. The hydraulic modulator 6 for changing the brake torque applied to the wheels 1 to 4 by adjusting the hydraulic pressure in the caliper of the steering wheel, the steering wheel angle sensor 8 for measuring the rotation angle of the steering wheel 7, and the center of gravity of the vehicle. Pressure connected between the yaw rae and the lateral acceleration sensor 9 and the lateral acceleration sensor 10 and the rear brakes 23 and 24 and the hydraulic modulator 6, respectively, which measure the yaw rae and the lateral acceleration of the vehicle body installed in the vehicle body. Proportional valves (25, 26), the wheel speed By inputting the voltage signals of the degree sensor (11-14), steering wheel angle sensor (8), yaw rate sensor (9), lateral acceleration sensor (10) and brake pressure sensor (5) to perform calculations related to the vehicle dynamics It consists of an electronic controller 40 which drives the hydraulic modulator 6 via a control signal line 16.

In this case, since a plurality of solenoid valves are built in the hydraulic modulator 6 to adjust the hydraulic pressure of the wheel cylinder or the caliper, the control signal line 16 for improving the driving safety of the vehicle is composed of a plurality of wires.

Referring to the operation of the vehicle safety control device configured as described above are as follows.

If the driver rotates the steering wheel 7 while the vehicle is running, the electronic controller 40 calculates the driving path directed by the driver from the input signal of the steering wheel angle sensor 8, and then the wheel speed sensor 11. 14) the actual driving path of the vehicle is calculated from the output signals of the steering wheel angle sensor 8, the yaw rate sensor 9, the lateral acceleration sensor 10 and the brake pressure sensor 5, The brake torque of the 4 wheels is controlled to compare the route with the actual driving route so that the difference is small.

In other words, the electronic controller 40 receives various sensor signals of the wheel speed sensors 11-14, the steering wheel angle sensor 8, the yaw rate sensor 9, the lateral acceleration sensor 10, and the brake pressure sensor 5. Calculate the vehicle's body-facing rate and vehicle side slip angle, and take the target yaw rate and lateral slip angle with reference to the driver's body, so that the oversteer or understeer of the vehicle By adjusting the hydraulic pressure of the caliper at the time of calculation, it is possible to control the actual yaw rate and the side slip angle of the vehicle body.

However, in the conventional driving safety control apparatus as described above, although the yaw rate can be measured from the input signal of the yaw rate sensor 9, the lateral slip angle of the vehicle body cannot be simply measured, so that a series of complicated calculations based on the vehicle dynamics are performed. There was a problem that became necessary.

The present invention has been made to solve the above problems, the object of each of the wheel speed, steering angle measured in the wheel speed sensor and steering wheel angle sensor, yaw rate sensor, lateral acceleration sensor and brake pressure sensor installed in the vehicle A vehicle safety control device that can independently control brake torque by calculating accurate vehicle side slip angle and target vehicle side slip angle from simple equations based on vehicle dynamics, using the rate, lateral acceleration and brake pressure. To provide.

Driving safety control device of the vehicle of the present invention for achieving this object, the road surface using the respective sensor signals measured by the wheel speed sensor and steering wheel angle sensor, yaw rate sensor, lateral acceleration sensor and brake pressure sensor installed in the vehicle The friction coefficient is obtained, the lateral tire friction force and the longitudinal tire friction force are obtained by using the obtained road surface friction coefficient, and the tire slip is obtained by using the sensor signal measured by each sensor, the lateral tire friction force and the longitudinal tire friction force. Estimates the angle, vehicle side slip angle, and lateral vehicle speed, obtains the target rate by referring to the rate of the vehicle body directed by the driver, and uses the sensor signal measured by each sensor and the lateral and longitudinal tire friction force and target rate. To obtain the target vehicle side slip angle, and then the body rate, target rate and vehicle side Comparing the lip angle and the side slip angle of the target vehicle to obtain a control signal that allows the body rate to follow the target rate and the side slip angle of the vehicle to estimate the side slip angle of the vehicle. Characterized in that it can be controlled independently.

1 is a block diagram of a driving safety control device of a typical vehicle.

Figure 2 is a block diagram of an electronic controller of the driving safety control apparatus according to the present invention.

3 is a view showing a plane model of a vehicle according to the present invention.

4 shows a steering angle and a tire slip angle.

* Description of the symbols for the main parts of the drawings *

40: electronic controller 41: road surface friction coefficient calculation unit

42: tire friction force calculation unit 43: vehicle dynamics observation unit

44: target rate calculation part 45: target vehicle side slip angle calculation part

46: wheel slip control unit

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the vehicle safety control apparatus of the present invention.

2 is a block diagram of an electronic controller of a vehicle safety control apparatus according to the present invention. The electronic controller 40 according to the present invention includes a wheel speed sensor 11 to 14 and a steering wheel angle sensor 8. Wheel speeds V _W1 , V _W2 , V _W3 , V _{W4 of} the sensor unit 50 including the sensor 9, the lateral acceleration sensor 10, and the brake pressure thinner 5, the steering angle δ _W , Body rate ( ), Lateral acceleration ( Road surface coefficient of friction calculation unit 41 and a road surface coefficient of friction coefficient calculated by the road surface coefficient of friction calculation unit 41 for calculating the friction coefficient of the road surface on the tire using the sensor signal of the brake pressure p Tire friction force calculation unit 42 for calculating the transverse tire friction force (F _S ) and the longitudinal tire friction force (F _B ) by using, and the various sensor signals and tire friction force calculation unit (measured by the sensor unit 50) Vehicle dynamics for estimating tire slip angle α, vehicle side slip angle β and lateral vehicle speed V _y from the lateral tire friction force F _S and the longitudinal tire friction force F _B obtained in 42). The target rate (referring to the observation unit 43 and the driver's body rate) ), The target yaw rate calculation unit 44, the various sensor signals measured by the sensor unit 50, and the lateral tire friction force F _S and the longitudinal tire friction force F _B obtained by the tire friction force calculation unit 42. ), A target vehicle side slip angle calculator 45 for calculating a target vehicle side slip angle β ₀ of the target vehicle using the target rate calculated by the target rate calculator 44, and the body rate ( ) And the target rate obtained by the target rate calculator 44 ( ) And compares the vehicle side slip angle β obtained by the vehicle dynamics observation unit 43 with the target vehicle side slip angle β ₀ obtained by the target vehicle side slip angle calculation unit 45, ( ) Is the target rate ) And a wheel slip control section 46 which obtains a control signal required by the hydraulic modulator 6 so that the vehicle side slip angle beta follows the target vehicle side slip angle beta ₀ .

Referring to the operation of the vehicle driving safety control apparatus of the present invention configured as described above are as follows.

First, Figure 3 shows a planar model of the vehicle according to the present invention, showing a planar model of the vehicle ignoring the influence of the suspension.

That is, in the present invention, the vehicle side slip angle is calculated by obtaining the vehicle speed in the y direction using the vehicle model of FIG. 3.

In the vehicle model shown in FIG. 3, δ _w is the steering angle of the front wheel steering vehicle, and F _B1 and F _S1 are the longitudinal tire friction or braking force and the transverse direction of the road surface on the front left wheel 1, respectively. Directional tire friction or turning force.

The braking force acts parallel to the tire plane and the turning force acts perpendicular to the tire plane.

F _B2 and F _S2 are the braking force and the turning force on the front right wheel 2, respectively, and F _B3 and F _S3 are the braking force and the lateral force on the rear left wheel 3 while the vehicle is turning. F _B4 and F _S4 are braking and lateral forces that the road surface exerts on the rear right wheel 4.

a and b are distances from the center of gravity of the vehicle to the front wheel axle and the rear wheel axle, and c is the distance from the center of gravity of the vehicle to the left or right wheel.

The xy axis represents the vehicle body fixed coordinate system whose origin is the center of gravity of the vehicle, and Ψ represents the rotation angle of the vehicle body in the xy plane.

On the other hand, when the driver rotates the steering wheel to turn the vehicle on a curved road, in order to generate the turning force of the vehicle at the contact surface between the tire and the road surface, the direction of the vehicle body, the tire direction, and the traveling speed direction of the vehicle are It does not match as shown in 4.

That is, FIG. 4 defines the steering angle δ _W , the tire slip angle α and the vehicle side slip angle β _W at the wheel in the interaction between the tire and the road surface, wherein the steering angle δ _W is The body direction, that is, the angle between the x-axis and the tire plane of FIG. 3, the tire slip angle α is the angle between the tire plane and the wheel travel speed direction, and the vehicle side slip angle β _{W at the} wheel is the body direction and the wheel Angle between advancing speed directions.

Therefore, it is established as following Formula (1).

β _W = α + δ _W (1)

First, the road surface friction coefficient calculation unit 41 of the electronic controller 40 according to the present invention is a signal measured by the sensor unit 50, that is, wheel speeds V _W1 , V _W2 , of the wheel speed sensors 11 to 14. V _W3 , V _W4 ), steering angle (δ _W ) of the steering wheel angle sensor 8, _and vehicle body rate of the yaw rate sensor 9 ( ), The lateral acceleration of the lateral acceleration sensor 10 ) And the brake coefficient p of the brake pressure sensor 5 to calculate the coefficient of friction on the tire of the road surface being operated.

Subsequently, when the road surface friction coefficient calculation unit 41 obtains a friction coefficient, the tire friction force calculation unit 42 uses the friction coefficient calculated by the road surface friction coefficient calculation unit 41 to lateral tire friction force F _S. Calculate and longitudinal tire friction force (F _B ).

At this time, the calculation performed by the tire friction force calculation unit 42 is as follows, and tire friction forces F _B and F _{S in} the longitudinal and lateral directions of one tire are given as follows.

Where C _λ is the longitudinal tire stiffness coefficient, C _α is the longitudinal tire stiffness coefficient, μ is the friction coefficient of the road surface estimated by the road surface friction coefficient calculating unit 41, and F _N is a vertical load on the tire.

And tire slip ratio (lambda) is defined as follows.

Here, V _W is the wheel speed when the brake torque is applied, and V _WN is the wheel speed that freely rotates when the brake is inactive.

From the above equations (2) and (3), the following equation is established.

If the tire slip angle α is assumed to be fine, equation (6) becomes as follows from equation (1).

That is, the tire friction force calculation unit 42 obtains the tire friction forces F _B and F _{S in the} longitudinal and lateral directions as described above with respect to the four wheels 1 to 4, respectively.

Subsequently, in the vehicle dynamics observer 43, the wheel speeds V _W1 , V _W2 , V _W3 , V _W4 measured by the sensor unit 50, the steering angle δ _W , and the vehicle body rate ( ), Lateral acceleration ( ), The tire slip angle α, the vehicle side slip angle β and the transverse vehicle speed V _y are estimated from the sensor signals of the brake pressure p.

The calculation performed by the vehicle dynamics observer 43 is as follows, and the motion equation of the vehicle with respect to the y direction in FIG. 3 is required as follows.

Where m is the mass of the vehicle, V _x and V _y are the vehicle velocities in the x and y directions, respectively.

Substituting Eq. (7) into Eq. (8) holds:

Here, β _F and β _R are vehicle slip angles at the front and rear axles, respectively, and λ ₁ , λ ₂ , λ ₃ , and λ ₄ are slip ratios of the four wheels.

The vehicle side slip angles β _F , β _R at the front and rear axles are given as follows.

Substituting 10) and (11) into equation (9), the vehicle speed V _{y in the} y direction is as follows.

Where A, B, and C are given by

As described above, the vehicle speed V _x in the x direction at the time of brake torque is estimated from the wheel speeds V _W1 , V _W2 , V _W3 and V _W4 measured by the wheel speed sensors 1 to 4 and the steering angle (Δ _W ) is obtained from the steering angle measured by the steering wheel angle sensor (8). ) Is measured by the rate sensor (9), Are measured by the lateral acceleration sensors 10, respectively, so that the vehicle speed V _{y in the} y direction can be calculated from equation (12).

Accordingly, the vehicle dynamics observation unit 43 obtains the vehicle side slip angle β through the following equation.

Subsequently, in the target rate calculation unit 44, the target rate ( ), And the target y-direction vehicle speed V _y0 is calculated as follows from equation (12).

Accordingly, the target vehicle lateral slip angle calculating section 45 in using the equation (17) targets the y direction the vehicle speed (V _y0) and x vehicle speed (V _X), the direction determined by the target by the following expression The vehicle side slip angle β ₀ is obtained.

As described above, the vehicle side slip angle β and the target vehicle slip angle β ₀ are accurately calculated. ) And the target rate obtained by the target rate calculation unit 44 ( ), And compare the vehicle side slip angle β obtained by the vehicle dynamics observation unit 43 with the target vehicle side slip angle β ₀ obtained by the target vehicle side slip angle calculation unit 45, respectively. Body rate ( ) Is the target rate ), And a control signal required by the hydraulic modulator 6 is obtained so that the vehicle side slip angle beta follows the target vehicle side slip angle beta ₀ .

Then, the brake torque is changed by the hydraulic modulator 6 according to the control signal, and thus the behavior of the vehicle is changed so that the vehicle can safely travel along the driving route.

On the other hand, the electronic controller 40 repeats the above calculation process every calculation time.

As described above, the present invention accurately calculates the vehicle side slip angle from an equation based on vehicle dynamics using sensor signals of four wheel speed, steering angle, body yaw rate, lateral acceleration, and brake pressure measured by each sensor. For example, when the target rate is calculated, the target vehicle side slip angle can also be accurately calculated through an equation based on the vehicle dynamics, thereby accurately and independently controlling the brake torque of the four wheels, thereby improving driving safety of the vehicle.

Claims (4)

The brakes of the four wheels are independently received by receiving the voltage signals of the wheel speed sensors 11 to 14, the steering wheel angle sensor 8, the yaw rate sensor 9, the lateral acceleration sensor 10, and the brake pressure sensor 5 as inputs. In the vehicle safety control apparatus including an electronic controller 40 for driving, The preconditioning controller 40 includes a wheel speed sensor 11 to 14, a steering wheel angle sensor 8, a yaw rate sensor 9, a lateral acceleration sensor 10, and a brake unit 5 including a pressure sensor 5. Wheel speed (V _W1 , V _W2 , V _W3 , V _W4 ), steering angle (δ _W ), ), Lateral acceleration ( Road surface coefficient of friction calculation unit 41 and a road surface coefficient of friction coefficient calculated by the road surface coefficient of friction calculation unit 41 for calculating the friction coefficient of the road surface on the tire using the sensor signal of the brake pressure p Tire friction force calculation unit 42 for calculating the transverse tire friction force (F _S ) and the longitudinal tire friction force (F _B ) by using, and the various sensor signals and tire friction force calculation unit (measured by the sensor unit 50) A vehicle for estimating the tire slip angle α, the vehicle side slip angle β and the transverse vehicle speed V _y from the lateral tire friction force F _S and the longitudinal tire friction force F _B obtained in 42). With reference to the dynamics observation unit 43 and the vehicle body rate aimed by the driver, the target rate ( ), The target yaw rate calculation unit 44, the various sensor signals measured by the sensor unit 50, and the lateral tire friction force F _S and the longitudinal tire friction force F _B obtained by the tire friction force calculation unit 42. ), The target rate obtained by the target rate calculator 44 ( And a target vehicle side slip angle calculation unit 45 for calculating a target vehicle side slip angle β _{0 of} the target vehicle using ) And the target rate obtained by the target rate calculation unit 44 ( ) And compares the vehicle side slip angle β obtained by the vehicle dynamics observation unit 43 with the target vehicle side slip angle β ₀ obtained by the target vehicle side slip angle calculation unit 45, ( ) Is the target rate ) And a wheel slip control section 46 which obtains a control signal required by the hydraulic modulator 6 so that the vehicle side slip angle β follows the target vehicle side slip angle β ₀ . Driving safety control system. The tire friction force calculating unit 42 calculates the longitudinal tire friction force F _B and the lateral tire friction force F _S using the following equations (2), (3) and (4). Driving safety control device for a vehicle, characterized in that. The method of claim 1, wherein the vehicle dynamics observer 43 calculates the vehicle speed V _y and the vehicle side slip angle [β] in the y direction using Equations (12) and (16), respectively. Driving safety control device for a vehicle. According to claim 1, wherein the vehicle dynamics observer 43 calculates the vehicle speed (V _y ) and the vehicle side slip angle (β) in each y direction by using the following equation (12) and equation (16). Driving safety control device for a vehicle.