KR101365008B1 - Control method for electronic stability control ina vehicle - Google Patents

Abstract

Detect each wheel speed, steering angle, lateral acceleration, yaw rate and throttle position, estimate vehicle speed from each detected wheel speed, estimate the desired yaw rate from the detected steering angle and lateral acceleration, The driver calculates the target speed from the desired yaw rate, determines the road surface condition of the vehicle from the detected lateral acceleration, and determines whether the vehicle is in the ESC evaluation mode or the normal mode to evaluate the handling of the vehicle. Disclosed is a vehicle attitude control method for improving vehicle performance by providing a braking force greater than the braking force in the normal mode to a wheel to improve a vehicle's entry speed in a vehicle handling evaluation situation.

Description

Vehicle control method {CONTROL METHOD FOR ELECTRONIC STABILITY CONTROL INA VEHICLE}

The present invention relates to a vehicle attitude control method, and more particularly, to a vehicle attitude control method for controlling the vehicle attitude by controlling the braking force of the vehicle.

In general, an electronic stability control (ESC) device is an apparatus for optimally controlling a vehicle's driving position, and is an anti-lock brake system (ABS) that prevents the wheel from being locked during braking. Next generation device. The ESC system instantly controls each of the four wheels independently in order to maintain stability when the vehicle is about to slide, enhancing driving stability on dry roads, rain, gravel roads and snow roads.

Such an ESC device has a yaw rate value desired by a driver estimated from a vehicle sensor such as a wheel speed sensor, a pressure sensor, a steering angle sensor, a lateral acceleration sensor, and an actual yaw rate value of a vehicle detected by the yaw rate sensor. To determine whether the state of the vehicle is an oversteer that is inward in the direction of the vehicle's turning or an understeer that is out of the direction of the vehicle's turning. The braking force is applied, and under understeering, the braking force is applied to the turning inner wheel to pressurize the brake hydraulic pressure to perform attitude control of the vehicle, thereby ensuring stability of the vehicle. That is, during oversteering, a braking force is applied to the outer wheel turning outer wheel to generate a compensating moment acting outward of the vehicle, thereby preventing loss of coordination of the vehicle, and under understeering, a braking force is applied to the inner wheel of the rear turning turning to the inside of the vehicle. By creating an acting compensation moment, the vehicle is prevented from being pushed outwards on the desired trajectory.

Conventionally, the vehicle can be stabilized by controlling the ESC according to the yaw rate behavior of the vehicle, but there is a limit in increasing the speed of entry of the vehicle when evaluating the handling of the vehicle under extreme road surface testing conditions.

One aspect of the present invention provides a vehicle attitude control method for adjusting the braking amount of the turning outer wheel during ESC control to improve the entry speed of the vehicle in the handling evaluation situation of the vehicle.

To this end, the vehicle attitude control method according to an aspect of the present invention detects each wheel speed, steering angle, lateral acceleration, yaw rate, and throttle position, estimates the vehicle speed from the detected wheel speeds, and detects the steering angle and transverse direction. The driver estimates the yaw rate desired by the driver, calculates a target speed from the detected yaw rate and the yaw rate desired by the driver, determines the road surface state of the vehicle from the detected lateral acceleration, and evaluates the handling of the vehicle. It is determined whether the ESC evaluation mode or the normal mode, and in the case of the ESC evaluation mode, providing a braking force greater than the braking force in the normal mode to the turning outer wheel.

In addition, the step of providing the braking force includes providing a braking force greater than the braking force in the normal mode to the front wheel turning outer wheel.

In addition, the braking force provided to the front wheel turning outer wheel in the step of providing the braking force includes greater than the braking force provided to the rear wheel turning outer wheel.

The braking force provided to the front wheel turning outer wheel and the rear wheel turning outer wheel in the providing of the braking force may be determined from the speed difference between the target speed and the vehicle speed.

Further, in the determining of the ESC evaluation mode, the estimated vehicle speed exceeds a preset speed value, the determined road surface state is a road surface state that is greater than or equal to a preset road friction coefficient, and the estimated vehicle speed and the calculated target speed are determined. If the speed difference is less than or equal to the preset speed, and the accelerator pedal is released, it includes determining the current mode as the ESC evaluation mode.

According to one aspect of the present invention described above, by adjusting the braking amount of the outer wheel turning in the ESC control it is possible to increase the vehicle entry speed in the ESC evaluation mode to evaluate the handling of the vehicle can improve the vehicle performance.

1 is a schematic control block diagram of a vehicle attitude control apparatus according to an embodiment of the present invention.
2 is a view for explaining the determination of the operation and release of the ESC evaluation mode in the vehicle attitude control apparatus according to an embodiment of the present invention.
3 is a view showing braking force provided to the turning outer wheels of the front wheel and the rear wheel in the ESC evaluation mode and the normal mode, respectively, in the vehicle attitude control apparatus according to the embodiment of the present invention.
4 is a control flowchart of a vehicle attitude control method according to an embodiment of the present invention.
5 is a view for explaining the increase in braking force to the front wheel turning outer wheel and the rear wheel turning outer wheel in the ESC evaluation mode in the vehicle attitude control apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1 shows a schematic control block of the vehicle attitude control apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the vehicle attitude control apparatus according to an exemplary embodiment of the present invention includes a sensor unit 10 and an ESC controller 100.

The sensor unit 10 includes a wheel speed sensor, a steering angle sensor, a lateral acceleration sensor, a yaw rate sensor, and a throttle position sensor.

Wheel speed sensors are installed on each wheel to detect each wheel speed.

The steering angle sensor detects the steering angle of the steering wheel during steering.

The lateral acceleration sensor detects lateral acceleration of the vehicle.

The yaw rate sensor detects the yaw rate of the vehicle,

The throttle position sensor detects the opening degree of the throttle valve controlled by the accelerator pedal of the vehicle.

The ESC controller 100 includes a vehicle speed estimating unit 20, a yaw rate estimating unit 30, a road surface determination unit 40, a target speed calculating unit 50, an ESC control unit 60, a braking force adjusting unit 70, and a driving force. It includes an adjusting unit 80.

The vehicle speed estimating unit 20 estimates the speed of the vehicle from each wheel speed detected by each wheel speed sensor.

The yaw rate estimation unit 30 estimates the yaw rate desired by the driver from the steering angles and the lateral accelerations respectively detected by the steering angle sensor and the lateral acceleration sensor using the vehicle model.

The road surface determination unit 40 determines whether the state of the road surface on which the vehicle is traveling is a low friction road surface, a middle friction road surface, or a high friction road surface using the magnitude of the lateral acceleration detected by the lateral acceleration sensor. That is, the state of the road surface is determined from the friction coefficient between the tire and the road surface.

The target speed calculator 50 calculates a target speed corresponding to the yaw rate error between the actual yaw rate detected by the yaw rate sensor and the yaw rate desired by the driver estimated through the yaw rate estimation unit.

The braking force control unit 70 controls the brake hydraulic pressure provided to each wheel-side wheel cylinder to adjust the braking force of the vehicle.

The driving force adjusting unit 80 controls the engine torque of the vehicle to adjust the driving force of the vehicle.

The ESC control unit 50 is provided with a speed difference between the vehicle speed estimated through the vehicle speed estimation unit 20 and the target speed calculated through the vehicle speed and the target speed calculator.

In addition, the ESC controller 50 receives the yaw rate difference between the yaw rate estimated by the driver estimated by the yaw rate estimation unit 30 and the actual yaw rate detected by the yaw rate sensor of the sensor unit 10.

In addition, the ESC control unit 50 receives the road surface information determined by the road surface determination unit 40.

In addition, the ESC controller 50 receives the throttle position information detected through the throttle position sensor of the sensor unit 10.

In addition, the ESC control unit 50 determines whether the current mode is the ESC evaluation mode for evaluating the handling of the vehicle by using the vehicle speed, the speed difference between the vehicle speed and the target speed, road surface information, and throttle position information.

In addition, when the current mode is the ESC evaluation mode, the ESC control unit 50 generates the appropriate compensation moment to improve the entry speed of the vehicle, thereby controlling the turning outer wheels of the front and rear wheels when controlling the ESC through the braking force control unit 70. Adjust the volume In particular, the ESC controller 50 may increase the vehicle entry speed by providing a braking force to the front wheel turning outer wheels while providing a predetermined braking force to the turning outer wheels of the front and rear wheels in the ESC evaluation mode, thereby improving vehicle performance. In this case, the ESC controller may additionally adjust the engine driving force through the driving force adjusting unit 80 if necessary.

The ESC evaluation mode is called a Consumer Report Avoidance Maneuver (CRAM) evaluation mode. In this CRAM evaluation mode, the driver uses the speed of entry through a given track as a factor indicating vehicle performance.

The ESC controller 100 has a control structure including input and output signals for the CRAM evaluation mode determination and control logic for the CRAM evaluation mode.

In addition, the ESC controller 100 basically receives the vehicle speed, the yaw rate desired by the driver, the actual yaw rate, the road surface state, the throttle position value, and the like to determine whether the current mode is the CRAM evaluation mode, and turns in the CRAM evaluation mode. By adjusting the braking force on the outer wheels, the vehicle's entry speed is increased to improve vehicle performance.

Figure 2 shows the determination of the operation and release of the ESC evaluation mode in the vehicle attitude control apparatus according to an embodiment of the present invention.

As shown in FIG. 2, the ESC control unit 50 determines the entry condition of the ESC evaluation mode and the release condition of the ESC evaluation mode according to the vehicle speed, the road surface state, the speed difference, and the accelerator pedal state.

First, the ESC controller 50 is a road surface state where the vehicle speed exceeds a preset speed Vth_ent, and the road surface state is equal to or greater than a preset road friction coefficient (eg, an intermediate road friction coefficient Med_mu), and the vehicle speed and the target speed. If the speed difference is less than or equal to a preset speed (del_Vcal, ent) and the accelerator pedal is released, it is determined that the current mode is the ESC evaluation mode and the current mode is changed to the ESC evaluation mode.

In addition, the ESC control unit 50 is a road surface state where the vehicle speed is less than or equal to the preset speed Vth_exit, the road surface state is less than a preset road friction coefficient (for example, the middle road friction coefficient Med_mu), and the speed between the vehicle speed and the target speed. If the difference is less than the preset speed (del_Vcal, exit) and the accelerator pedal is in the activated state, it is determined that the current mode is the normal mode and the current mode is changed to the normal mode.

Figure 3 shows the braking force provided to the turning outer wheels of the front and rear wheels in the ESC evaluation mode and the normal mode, respectively, in the vehicle attitude control apparatus according to an embodiment of the present invention.

As shown in FIG. 3, the ESC control unit 50 controls the braking force provided to the front wheel and the rear wheel outer wheel in the ESC evaluation mode to be higher than in the normal mode.

For example, in the ESC evaluation mode, the ESC controller 50 provides a first braking force (Gain 1 * del_V) to the rear wheel turning outer wheel, and applies a first braking force (Gain 1 * del_V) to the outer wheel turning outer wheel. Provide the braking force (Gain 1 * del_V + Gain 2 * del_V) which is the sum of the two braking forces (Gain 2 * del_V). In this case, the first braking force Gain 1 * del_V is a value obtained by multiplying the difference between the target speed and the vehicle speed del_V by the first control gain Gain 1 preset for each vehicle. The second braking force Gain 2 * del_V is a value obtained by multiplying the difference between the target speed and the vehicle speed del_V by the second control gain Gain 2 preset for each vehicle.

In this case, it is possible to provide different braking force to the front wheel turning outer wheel and the rear wheel turning outer wheel instead of the first braking force Gain 1 * del_V.

In the normal mode, the ESC controller 50 provides the first braking force Gain 1 * del_V to the front wheel and the rear wheel turning outer wheels, respectively. At this time, it is possible to provide different braking force to the front wheel turning outer wheel and the rear wheel turning outer wheel instead of the first braking force (Gain 1 * del_V), but to provide a smaller braking force than in the ESC evaluation mode.

Figure 4 shows the control flow for the vehicle attitude control method according to an embodiment of the present invention.

Referring to FIG. 4, first, the ESC controller 100 detects each wheel speed, steering angle, lateral acceleration, yaw rate, and throttle position through the sensor unit 10 (100).

After sensing various information through the sensor unit 10, the ESC controller 100 estimates the vehicle speed from each detected wheel speed (110).

After estimating the vehicle speed, the ESC controller 100 estimates the desired yaw rate from the steering angle and the lateral acceleration detected by the sensor unit 120 (120).

After estimating the yaw rate desired by the driver, the ESC controller 100 calculates a target speed from the estimated yaw rate desired by the driver and the yaw rate detected by the sensor unit 10 (130).

After calculating the target speed, the ESC controller 100 determines the road surface state from the lateral acceleration detected by the sensor unit 10 (140).

Thereafter, the ESC controller 100 determines whether the current mode is the ESC evaluation mode (150).

At this time, the ESC controller 100 is a road surface state where the vehicle speed exceeds a preset speed Vth_ent, and the road surface state is equal to or greater than a preset road friction coefficient (for example, an intermediate road friction coefficient Med_mu), and the vehicle speed and the target speed. If the speed difference is less than or equal to a preset speed (del_Vcal, ent) and the accelerator pedal is released, it is determined that the current mode is the ESC evaluation mode.

In addition, the ESC controller 100 is a road surface state in which the vehicle speed is less than or equal to a preset speed (Vth_exit), the road surface state is less than a predetermined road friction coefficient (for example, an intermediate road friction coefficient (Med_mu)), and the speed between the vehicle speed and the target speed. If the difference is less than the preset speed (del_Vcal, exit) and the accelerator pedal is activated, it is determined that the current mode is the normal mode.

If the determination result of the operation mode 150 is the ESC evaluation mode, the ESC controller 100 increases the braking force of the turning outer wheel to match the ESC evaluation mode. At this time, the ESC controller 100 provides the first braking force (Gain 1 * del_V) to the rear wheel turning outer wheel, and the first braking force (Gain 1 * del_V) and the second braking force (Gain 2 * del_V) to the outer wheel turning outer wheel. This provides the combined braking force (Gain 1 * del_V + Gain 2 * del_V). Therefore, in the ESC evaluation mode, the braking force (basic braking force + additional braking force) larger than the braking force (basic braking force) in the normal mode can be provided to the turning outer wheel, thereby increasing the vehicle's entry speed and improving vehicle performance. have.

In particular, the front wheel turning outer wheel is provided with a braking force (basic braking force + additional braking force) larger than the braking force in the normal mode (basic braking force).

On the other hand, when it is determined that the operation mode 150 is not the ESC evaluation mode, the ESC controller 100 determines that the current mode is the normal mode, and provides the first braking force (Gain 1 * del_V) to the front wheel and the rear wheel turning outer wheels, respectively. At this time, it is possible to provide different braking force to the front wheel turning outer wheel and the rear wheel turning outer wheel instead of the first braking force (Gain 1 * del_V), but to provide a smaller braking force than in the ESC evaluation mode.

Figure 5 shows that in the vehicle attitude control apparatus according to an embodiment of the present invention to provide a braking force to the front wheel turning outer wheel and the rear wheel turning outer wheel in the ESC evaluation mode.

As shown in FIG. 5, the braking force (basic braking force + additional braking force) greater than the braking force (basic braking force) in the normal mode is provided to the turning outer wheel in the ESC evaluation mode.

In particular, the front wheel turning outer wheel is provided with a braking force (basic braking force + additional braking force) larger than the braking force in the normal mode (basic braking force).

In addition, the braking force (basic braking force + additional braking force) provided to the front wheel turning outer wheel is greater than the braking force (basic braking force) provided to the rear wheel turning outer wheel.

10: sensor unit 20: vehicle speed estimation
30: Yorate Chu Administration 40: Road Decision
50: target speed calculation unit 60: ESC control unit
70: braking force control unit 80: driving force control unit
100: ESC controller

Claims (5)

Detects each wheel speed, steering angle, lateral acceleration, yaw rate and throttle position,
Estimating a vehicle speed from the sensed wheel speeds,
Estimate the yaw rate desired by the driver from the detected steering angle and the lateral acceleration,
Calculating a target speed from the detected yaw rate and the desired yaw rate of the driver,
Determining the road surface state of the vehicle from the detected lateral acceleration;
Determine whether the ESC evaluation mode or normal mode for evaluating the handling of the vehicle,
And, in the ESC evaluation mode, providing a braking force greater than that of the normal mode to the turning outer wheel. The method of claim 1,
And providing a braking force greater than the braking force in the normal mode to the front wheel turning outer wheel in the step of providing the braking force. 3. The method of claim 2,
And the braking force provided to the front wheel turning outer wheel in the step of providing the braking force is greater than the braking force provided to the rear wheel turning outer wheel. The method of claim 3,
And the braking force provided to the front wheel turning outer wheel and the rear wheel turning outer wheel in the step of providing the braking force is determined from the speed difference between the target speed and the vehicle speed. The method of claim 1,
In the determining of the ESC evaluation mode, the estimated vehicle speed exceeds a preset speed value, the determined road surface condition is a road surface state that is equal to or greater than a preset road friction coefficient, and a speed between the estimated vehicle speed and the calculated target speed. And determining the current mode as the ESC evaluation mode when the vehicle is below a preset speed and the accelerator pedal is released.

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