KR100806077B1 - The method of Wheel speed calculation for vehicle - Google Patents

Abstract

The present invention relates to a driving stability attitude control method of a vehicle, and more particularly, to a reference speed correction method of a vehicle wheel used for slip calculation using a yaw rate sensor and a steering sensor during turning control.

When the vehicle is turning, the acceleration in the lateral direction acts on the vehicle so as to obtain a reference body speed based on non-drive wheels as in a two-wheel drive vehicle, or by using only a G sensor as in a four-wheel drive vehicle. In the case of obtaining the vehicle speed, there is a problem in that the braking performance and the acceleration performance are deteriorated during ABS and TCS control due to the wrong determination of the actual vehicle speed of the turning vehicle. In addition, the yaw rate sensor is used to correct the vehicle speed when turning the vehicle. However, this method also improves the existing body speed similarly to the actual vehicle speed, but reflects the speed difference between the front and rear wheels at low speed. It was not possible to calculate the more accurate reference speed.

Accordingly, an object of the present invention is to provide a method of calculating a reference speed of a vehicle wheel used for slip calculation by using a yaw rate sensor and a steering sensor during turning control in order to solve the above problems.

Wheel, reference speed

Description

The method of wheel speed calculation for vehicle}

1 is a block diagram for explaining the calculation of the reference speed of a wheel in an ABS vehicle according to an embodiment of the present invention.

Figure 2 is a flow chart showing a reference speed calculation method of the vehicle wheel of the present invention.

3 is a view showing graphs of constants applied when calculating a wheel reference speed of the present invention.

(a) is a graph showing the relationship between the yaw rate gain constant and the body reference speed.

(b) is a graph showing the relationship between steering angle gain constant and body reference speed.

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

10: sensor unit 20: control unit

30: braking actuator 40: engine output

The present invention relates to a driving stability attitude control method of a vehicle, and more particularly, to a reference speed correction method of a vehicle wheel used for slip calculation using a yaw rate sensor and a steering sensor during turning control.

In general, the anti-lock brake system (ABS) and the traction control system (TCS), which are electronic control systems of the vehicle, are used to secure the braking and acceleration of the vehicle during sudden braking or acceleration of the vehicle. As a device, it is possible to prevent understeer or oversteer, which is likely to occur during turning of the vehicle.In order to secure braking performance or acceleration performance in the ABS or TCS system, It is very important to ask.

Conventionally, in order to accurately calculate the speed of such a vehicle, the two-wheel drive vehicle and the four-wheel drive vehicle are divided into two-wheel drive vehicles, and the fastest wheel speed among the wheel speeds of the non-drive wheels is obtained as the reference vehicle speed. On the other hand, in the case of a four wheel drive vehicle, the reference wheel speed is estimated using the G sensor for detecting the longitudinal acceleration of the vehicle after estimating the fastest wheel speed among the wheel speeds of the four wheels. Correct it.

However, when the vehicle is turning, the acceleration in the lateral direction acts on the vehicle so as to obtain a reference body speed based on non-drive wheels as in a two-wheel drive vehicle, or to use only a G sensor as in a four-wheel drive vehicle. In the case of obtaining the reference vehicle speed, there is a problem that the braking performance and the acceleration performance are deteriorated during ABS and TCS control due to the incorrect determination of the actual vehicle speed of the turning vehicle.

In addition, the yaw rate sensor was used to correct the vehicle speed when turning the vehicle. However, this also improved the existing body speed similarly to the actual vehicle speed, but reflected the speed difference between the front and rear wheels at low speed. It was not possible to calculate the more accurate reference speed.

Accordingly, an object of the present invention is to provide a method of calculating a reference speed of a vehicle wheel used for slip calculation by using a yaw rate sensor and a steering sensor during turning control in order to solve the above problems.

The present invention for achieving the above object is a wheel speed sensor for detecting the wheel speed at each wheel, yaw rate sensor for detecting the degree of turning of the vehicle, steering angle sensor for detecting the steering degree of the vehicle The method for calculating a wheel reference speed of a vehicle includes estimating a reference body speed of the vehicle based on the wheel speed signal detected by the wheel speed sensor, and using the turning accuracy of the vehicle detected by the yaw rate sensor. Calculating a correction coefficient of the vehicle, correcting the estimated reference body speed using the calculated correction coefficient, and determining a turning degree of the vehicle detected from the yaw rate sensor and the steering angle sensor based on the corrected reference body speed. Calculating reference speeds of the front wheels and the rear wheels of the vehicle, respectively.

Referring to the present invention as described above in detail with reference to the accompanying drawings 1 to 3 as follows.

1 is a block diagram illustrating the calculation of a reference speed of a wheel in an ABS vehicle according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a method of calculating a reference speed of a vehicle wheel according to the present invention.

First, referring to FIG. 1, the detailed configuration is as follows.

The present invention consists of a sensor unit 10, the control unit 20, the braking actuator 30, the engine output unit 40.

The sensor unit 10 is provided in each wheel cylinder (not shown), the wheel speed sensor 11 for detecting the wheel speed, the ground (G) sensor 12 for detecting the longitudinal deceleration of the vehicle and And a yaw rate sensor 13 for detecting the turning degree of the vehicle and a steering angle sensor 14 for detecting the steering degree of the vehicle.

The control unit 20 inputs a wheel speed signal output from each wheel speed sensor 11 to calculate a wheel speed of the wheel speed calculation unit 21 and the ground (G) sensor 12 of the vehicle detected by The wheel speed calculated from the wheel speed calculation unit 21 after integrating the deceleration acceleration calculating unit 22 for calculating the deceleration acceleration and the deceleration speed calculated by the deceleration acceleration calculating unit 22 when the vehicle is braking. The wheel value calculated from the wheel speed calculation unit 21 after integrating the longitudinal acceleration calculated from the longitudinal deceleration acceleration calculation unit 22 when the vehicle is being accelerated is estimated. The reference vehicle speed estimation unit 23 and the yaw rate sensor 13 which estimate the reference vehicle speed are compared with the lowest wheel speed among the speeds, and the preset vehicle coefficient By reference body speed After calculating the correction value, if the vehicle is in braking state, the reference body speed is corrected by subtracting the correction coefficient from the reference body speed.If the vehicle is in an acceleration state, the reference body speed is calculated by adding the correction coefficient to the reference body speed. A reference vehicle speed correction unit 24 for correcting a reference and a front wheel and rear wheel reference speed calculator for calculating reference speeds of the front and rear wheels in consideration of the yaw rate and steering degree of the vehicle based on the corrected reference body speed; 25, a slip ratio calculating section 26 for calculating a slip ratio at each wheel using the calculated reference speeds of the front and rear wheels, and a braking actuator 30 so that the calculated slip ratio reaches an appropriate slip ratio. It consists of an ABS control unit 27 for controlling the TCS control unit 28 for controlling the engine output unit 40.

The braking actuator unit 30 adjusts the hydraulic pressure supplied to the wheel cylinders of the respective wheels according to the control signal of the ABS control unit 27.

The engine output unit 40 controls the driving force of the engine in accordance with the control signal of the TCS control unit 28.

Looking at the control method with reference to FIG.

First, it is determined whether the vehicle currently being driven is in a braking state or an acceleration state. The driving state of the vehicle is determined according to the driver's braking intention and acceleration intention, and the braking intention and acceleration intention are driven by the driver's brake pedal and acceleration. This can be determined by the pedal operation.

When the driver brakes the vehicle by operating the brake pedal, the wheel speed signal 11 and the deceleration acceleration signal output from the wheel speed sensor 11 and the ground (G) sensor 12 and the respective wheel speed calculator 21 are used. The deceleration acceleration calculation unit 22 inputs and detects the wheel speed and the deceleration speed, respectively.

Thereafter, the reference body speed estimator 23 of the controller 20 estimates the reference body speed by comparing the speed value obtained by integrating the speed reduction calculated by the longitudinal acceleration calculator 22 and the detected wheel speed value. do.

At this time, if the vehicle is four-wheel drive, the reference body speed estimator 23 compares the fastest wheel speed value among the detected wheel speeds with the speed value integrated with the detected closing speed, and sets the reference body speed to the highest value among them. Estimate. On the other hand, when the vehicle is two-wheel drive, the reference body speed estimator 23 estimates the fastest wheel speed among the wheel speeds of the non-drive wheels as the reference body speed.

When the reference vehicle speed is estimated, in order to correct the reference vehicle speed according to the turning degree of the vehicle, the reference body speed correcting unit 21 of the control unit 20 rotates the vehicle from the yaw rate sensor 13, that is, the yaw rate ( φ) is detected and the correction coefficient Vφ necessary for the correction of the reference vehicle body speed is calculated using the detected turning degree φ of the vehicle and the preset vehicle coefficient Kv, which is expressed by the following equation.

[Equation 1]

Where Vφ is the correction coefficient [Km / h] of the reference body speed, Kv is the vehicle coefficient [m / deg], φ is the yaw rate, Tr is the left and right spacing [m] of each wheel, and π is 180 [1 / deg ]to be.)

When the correction coefficient for correcting the reference vehicle speed is calculated as in Equation 1, the reference vehicle speed correction unit 24 of the control unit 20 calculates the reference vehicle speed at the time of turning the vehicle using the calculated correction coefficient. Correct it. At this time, whether the vehicle is a four-wheel drive vehicle or a two-wheel drive vehicle, the reference body speed correcting unit 24 corrects the following equation (2).

[Equation 2]

(Vref 'is the corrected reference body speed, Vref ″ is the estimated reference body speed, and Vφ is the correction coefficient of the reference body speed.)

On the other hand, if the driver operates the accelerator pedal and the current vehicle is in an acceleration state,

The reference body speed estimator 23 of the controller 20 estimates the reference body speed by comparing the speed value obtained by integrating the longitudinal acceleration of the longitudinal deceleration calculation unit 22 with the wheel speed value of the wheel speed calculator 21.

At this time, if the vehicle is a four-wheel drive, the reference body speed estimator 23 of the control unit 20 compares the slowest wheel speed value among the detected wheel speeds with the speed value integrating the longitudinal acceleration, and sets the smaller value among the reference vehicle bodies. It is estimated by speed.

On the other hand, if the vehicle is two-wheel drive, since the wheel speed of the non-drive wheel is the same, the wheel speed of any one of them is estimated as the reference vehicle speed.

When the reference vehicle speed is estimated, the reference vehicle speed correction unit 24 of the control unit 20 detects the yaw rate of the vehicle from the yaw rate sensor 13 to correct the reference vehicle speed according to the turning degree of the vehicle. Using the yaw rate φ and the preset vehicle coefficient Kv, it is applied to Equation 1 to calculate a correction coefficient Vφ.

When the correction coefficient Vφ for calculating the estimated reference body speed is calculated, the reference body speed correcting unit 24 of the controller 20 calculates the reference body speed when the vehicle is turning by using the correction coefficient Vφ. Will be corrected. At this time, the correction when the vehicle is in an acceleration state is corrected separately in the case of a four-wheel drive vehicle and a two-wheel drive vehicle, in the case of a two-wheel drive vehicle is corrected using Equation 2 above, and in the case of a four-wheel drive vehicle as shown in Equation 3 below. It is divided and corrected.

[Equation 3]

(Vref 'is the corrected reference body speed, Vref ″ is the estimated reference body speed, and Vφ is the correction coefficient of the reference body speed.)

The front wheel and rear wheel reference speed calculator 25 of the control unit 20 determines the driving state of the vehicle as described above, and uses the reference body speed corrected in consideration of the turning degree of the vehicle at the time of acceleration and braking, respectively. The reference speeds of the front and rear wheels are calculated based on the yaw rate and steering angle of the wheel.

In addition, the reference speed of each of the front and rear wheels is calculated separately from the acceleration and braking time. First, the reference speeds of the front and rear wheels during acceleration are as shown in Equation 4 below. The reference speed is calculated as shown in Equation 5 below.                     

[Equation 4]

[Equation 5]

Where Vref (R) is the rear wheel reference speed, Vref (F) is the front wheel reference speed, Vref 'is the corrected reference body speed, Vφ is the correction factor of the reference body speed, and φ is the yaw rate sensor Rate value, δ is steering angle value measured by steering angle sensor, K1 is yaw rate gain constant value, K2 is steering angle gain constant value)

Each of the yaw rate gain constants K1 and the steering angle gain constants K2 is a value that changes according to the vehicle body speed as shown in FIG. 3, and the yaw rate gain constant K1 is a reference speed Vref. The steering angle gain constant (K2) is inversely proportional to the reference speed (Vref).

As shown in Equation 4 and Equation 5, the reference speeds Vref (F) and Vref (R) of the front and rear wheels of the vehicle are calculated in consideration of the yaw rate value and the steering angle value, and the slip of the control unit 20 is calculated. The rate calculator 26 calculates a slip ratio using the calculated reference speeds Vref (F) and Vref (R) of each of the front and rear wheels. By controlling the engine output unit 40 through the control unit 28 to adjust the driving force of the engine, and during braking by controlling the braking actuator 30 through the ABS control unit 27 to adjust the pressure supplied to the wheel cylinder ABS Control will be performed.

As described above, the vehicle body reference speed is corrected by taking into account the yaw rate of the vehicle, and the reference speeds of the front and rear wheels are calculated by considering the yaw rate and the steering angle based on the corrected body reference speed. ABS and TCS can be operated in the optimal state and the vehicle's braking performance, acceleration performance and vehicle stability can be secured.

Claims (9)

In the method for calculating the reference speed of each wheel of a vehicle equipped with a plurality of sensors for detecting movement information when the vehicle is running, Estimating a reference vehicle speed of the vehicle based on motion information obtained from the plurality of sensors; correcting a reference vehicle speed using motion information obtained from the plurality of sensors; Calculating reference speeds of the front and rear wheels of the vehicle using motion information obtained from the two sensors, And calculating reference speeds of the front wheels and the rear wheels of the vehicle by calculating reference speeds of the front and rear wheels of the vehicle using the turning information of the vehicle. The method of claim 1, And the sensor is a wheel speed sensor and the motion information is a wheel speed signal in the reference body speed estimating step of the vehicle. The method of claim 1, The step of correcting the reference vehicle speed is performed by calculating a correction coefficient using the turning information of the vehicle obtained from the sensor, and correcting the estimated reference vehicle speed using the calculated correction coefficient. Speed calculation method. delete The method of claim 1, One sensor of the plurality of sensors is a yaw rate sensor, the motion information is a reference speed calculation method of the vehicle wheel, characterized in that the yaw rate value. The method of claim 1, One sensor of the plurality of sensors is a yaw rate sensor, the other sensor is a steering angle sensor, the motion information of each of the yaw rate sensor and the steering angle sensor is a yaw rate value and a steering angle value, characterized in that . In the method for calculating the reference speed of each wheel of a vehicle equipped with a plurality of sensors for detecting movement information when the vehicle is running, Estimating a reference vehicle speed of the vehicle based on motion information obtained from the plurality of sensors; correcting a reference vehicle speed using motion information obtained from the plurality of sensors; Calculating reference speeds of the front and rear wheels of the vehicle using motion information obtained from the two sensors, Computing the reference speed of each of the front wheel and the rear wheel of the vehicle is calculated by the following equation when the vehicle is accelerated. [Equation]

(Vref (R) is the reference speed at the rear wheel, Vref (F) is the reference speed at the front wheel, Vref 'is the corrected reference body speed, Vφ is the correction factor of the reference body speed, φ is the yaw rate value measured by the yaw rate sensor) , δ is steering angle value measured by steering angle sensor, K1 is yaw rate gain constant value, K2 is steering angle gain constant value) In the method for calculating the reference speed of each wheel of a vehicle equipped with a plurality of sensors for detecting movement information when the vehicle is running, Estimating a reference vehicle speed of the vehicle based on motion information obtained from the plurality of sensors; correcting a reference vehicle speed using motion information obtained from the plurality of sensors; Calculating reference speeds of the front and rear wheels of the vehicle using motion information obtained from the two sensors, In the step of calculating the reference speed of the front wheel and the rear wheel of each of the vehicle, the reference speed calculation method of the vehicle wheel, characterized in that performed by the following equation when the current vehicle is braking. [Equation]

(Vref (R) is the reference speed on the rear wheel side, Vref (F) is the reference speed on the front wheel side, Vref 'is the corrected reference body speed, VΦ is the correction factor of the reference body speed, Φ is the yaw rate value measured by the yaw rate sensor) , δ is steering angle value measured by steering angle sensor, K1 is yaw rate gain constant value, K2 is steering angle gain constant value) The method according to claim 7 or 8, And the yaw rate gain constant value is proportional to the body reference speed, and the steering angle gain constant value is inversely proportional to the body reference speed.

Images