KR19990000242A - Rolling control apparatus of a vehicle and control method thereof - Google Patents

Abstract

The present invention relates to a rolling control technique of an automobile which can control the damping coefficient of a shock absorber based on a steering angle signal, a steering angle speed signal and a vehicle speed signal, thereby providing an automobile adjustment stability not only in a transient state but also in a steady- A steer angle signal, a vehicle speed signal and a vehicle speed signal, calculates a steady state lateral acceleration on the basis of the detected steering angle signal and the detected vehicle speed signal, Calculating a transient lateral acceleration based on the signal and the detected vehicle speed signal; Calculates the maximum lateral acceleration based on the calculated steady state lateral acceleration and the calculated transient lateral acceleration, and assigns the damping coefficients of the front wheel shock absorber and the rear wheel shock absorber, respectively, based on the calculated maximum lateral acceleration; Calculating an absolute value difference between the calculated steady state lateral acceleration and the calculated transient state lateral acceleration; And technical means for adaptively determining respective damping coefficients of the front wheel shock absorber and the rear wheel shock absorber based on the respective damping coefficients of the front wheel shock absorber and the rear wheel shock absorber and the calculated absolute difference of lateral acceleration, It is possible to improve the running stability, the adjustment stability and the ride comfort of the automobile.

Description

Rolling control apparatus of a vehicle and control method thereof

The present invention relates to an apparatus for controlling rolling of an automobile, and more particularly to a system for controlling the rolling of an automobile by adaptively controlling a damping coefficient of a shock absorber at the time of driving the automobile at high speed, And a method of controlling the same.

As is well known, a shock absorber of an automobile absorbs natural vibration due to a shock received by a spring during running of the vehicle, thereby attenuating the vibration, thereby suppressing the roll motion of the vehicle, thereby improving the driving stability, adjustment stability, It is a kind of suspension device.

To this end, a method of determining a damping coefficient of a shock absorber based on a steering angle velocity signal and a vehicle speed signal detected through a steering angle velocity sensor and a vehicle velocity sensor is used for rolling stability of a vehicle in the past.

That is, in the conventional method, the damping coefficient of the shock absorber is determined on the basis of the detected steering angle velocity signal and vehicle speed signal. For example, as shown in Fig. 4, when the lateral acceleration of the vehicle is large, The rolling motion of the automobile is suppressed to improve the rolling stability of the automobile.

However, in the conventional art as described above, since the damping coefficient of the shock absorber is converted into the hard mode based on the detected steering angle velocity signal and the vehicle speed signal to control only the roll motion, the steering characteristic in the transient state can not be controlled, The controllability and stability can not be improved. If the steering angle is not converted, the damping coefficient is switched to the soft mode, which can seriously affect the stability of the vehicle when traveling on the curve road at high speed.

For example, when the vehicle travels a curve road having a short and large rotation angle, the above-mentioned conventional technique determines an appropriate shock absorber damping coefficient on the basis of the detected steering angle velocity signal and vehicle speed signal, Although the roll motion can be smoothly controlled, for example, when the vehicle travels on a long and smooth curve road at a high speed, the change in the steering angle is large, but the actual steering angle velocity signal is small so that the damping coefficient of the shock absorber can not be appropriately determined The roll motion of the vehicle can not be effectively controlled.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a steering control apparatus and a steering control apparatus for controlling the damping coefficient of a shock absorber based on a steering angle signal, And an object of the present invention is to provide a rolling control device for an automobile which can provide adjustment stability.

Another object of the present invention is to provide a steering stability control system for a vehicle that can control the damping coefficient of a shock absorber according to a lateral acceleration calculated based on a steering angle signal, a steering angle velocity signal and a vehicle speed signal, The present invention is directed to a rolling control method for an automobile.

According to an aspect of the present invention for achieving the above object, there is provided an apparatus for controlling a roll motion generated during driving of a vehicle by controlling front wheel shock absorbers and rear wheel shock absorbers respectively mounted on an automobile, A detection block for detecting a steering angle of the steering wheel, detecting a steering angle velocity of the steering wheel, and detecting a vehicle speed of the vehicle during running; A first lateral acceleration calculation block for calculating a steady state lateral acceleration of the automobile based on the detected steering angle signal and the detected vehicle speed signal; A second lateral acceleration calculation block for calculating the transient lateral acceleration of the automobile based on the detected steering angle velocity signal and the detected vehicle velocity signal; Calculates the maximum lateral acceleration based on the calculated steady state lateral acceleration and the calculated transient lateral acceleration, assigns the damping coefficients of the front wheel and the rear wheel shock absorber, respectively, on the basis of the calculated maximum lateral acceleration, A lateral acceleration comparison block for calculating an absolute value difference between the steady state lateral acceleration and the calculated transient lateral acceleration; And a damping coefficient determination block for adaptively determining respective damping coefficients of the front wheel and the rear wheel shock absorber based on the respective damping coefficients of the front wheel and the rear wheel shock absorber and the calculated absolute difference of lateral acceleration, Of the rolling control device.

According to another aspect of the present invention for achieving the above object, there is provided a method for controlling roll motion generated during running of a vehicle by controlling front wheel shock absorbers and rear wheel shock absorbers respectively mounted on an automobile, A steering angle velocity signal and a vehicle speed signal; Calculating a steady state lateral acceleration of the automobile based on the detected steering angle signal and the detected vehicle speed signal and calculating a transient lateral acceleration of the automobile based on the detected steering angle speed signal and the detected vehicle speed signal; Calculating a maximum lateral acceleration of the automobile on the basis of the calculated steady state lateral acceleration and the calculated transient lateral acceleration; Allocating damping coefficients of the front wheel shock absorber and the rear wheel shock absorber based on the calculated maximum lateral acceleration; Calculating an absolute value difference between the calculated steady state lateral acceleration and the calculated transient state lateral acceleration; And a step of adaptively determining respective damping coefficients of the front wheel shock absorber and the rear wheel shock absorber on the basis of the respective damping coefficients of the front wheel shock absorber and the rear wheel shock absorber and the calculated absolute difference of lateral acceleration A rolling control method of an automobile is provided.

1 is a block diagram of a rolling control system for a vehicle according to a preferred embodiment of the present invention;

2 is a flow chart showing a process of controlling rolling by controlling a damping coefficient of a shock absorber based on a lateral acceleration calculated based on a steering angle signal, a steering angle velocity signal and a vehicle speed signal according to the present invention,

FIG. 3A is a graph showing damping coefficient values according to the maximum lateral acceleration calculated according to the present invention,

FIG. 3B is a graph showing the front and rear wheel shock absorber damping ratios according to the absolute value difference of the lateral acceleration according to the present invention,

4 is a graph showing the relationship between soft and hard when the shock absorber is controlled according to the conventional method.

Description of the Related Art [0002]

110: sensing block 112: steering angle sensor

114: Steering angle velocity sensor 116: Vehicle speed sensor

130, 150: lateral acceleration calculation block 170: lateral acceleration comparison block

190: Damping coefficient determination block

These and other objects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

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

A key feature of the present invention is to detect a lateral acceleration in a steady state on the basis of a steering angle signal and a vehicle speed signal detected during running of an automobile and to detect a transverse acceleration in a transient state based on a steering angle speed signal and a vehicle speed signal, And calculates a difference between the absolute value of the detected steady-state lateral acceleration and the absolute value of the transient lateral acceleration. Based on the calculated absolute value difference signal, the damping coefficient of the rear wheel shock absorber and the damping coefficient of the front wheel shock absorber are adaptively And the driving stability, the adjustment stability, and the ride comfort are improved at the time of running of the automobile, and these technical points will be more clearly understood from the following preferred embodiments.

1 is a block diagram of a rolling control system for a vehicle according to a preferred embodiment of the present invention.

As shown in the figure, the rolling control apparatus of the present invention includes a sensing block 110, a first lateral acceleration calculation block 130, a second lateral acceleration calculation block 150, a lateral acceleration comparison block 170, And a coefficient determination block 190. The sensing block 110 includes a steering angle sensor 112, a steering angle velocity sensor 114, and a vehicle speed sensor 116.

Referring to FIG. 1, the steering angle sensor 112 detects a steering angle velocity of a vehicle mounted on a predetermined position on a steering wheel axis, for example, and detects a steering angle velocity of the vehicle. The steering angle velocity signal detected here is a first lateral acceleration Computation block 130 is provided.

The steering angle velocity sensor 114 detects a range of the steering angle of the vehicle, for example, mounted on a predetermined position on the steering wheel axis, and detects the steering angle velocity signal. The steering angle velocity signal detected by the steering angle velocity sensor 114 is transmitted to a second lateral acceleration calculation block Lt; / RTI >

The vehicle speed sensor 116 detects the speed of the running vehicle, and the detected vehicle speed signal is provided to the first and second lateral acceleration calculation blocks 130 and 150, respectively.

Next, the first lateral acceleration calculation block 130 calculates a steady state lateral acceleration based on the detected steering angle signal and the vehicle speed signal provided from the steering angle sensor 112 and the vehicle speed sensor 116, respectively.

That is, using a two-degree-of-freedom vehicle model that takes into account the rotational (yaw) motion and slip (slip angle) motion of the vehicle, the transfer function of the lateral acceleration for the detected steering angle input can be obtained using the following equation.

[Equation 1]

In the equation (1), δ denotes an input steering angle, a _δ denotes a lateral acceleration, T ₁ and T ₂ denote time constants, ζ denotes a damping coefficient, and Wn denotes a natural frequency of the vehicle. It can be calculated through the specifications of the car.

In the equation (1), (a _隆 / 隆) ss represents the lateral acceleration gain in the steady state. In the first lateral acceleration calculation block 130, the steering angle signal and the vehicle speed signal The lateral acceleration calculated in the steady state is provided to the lateral acceleration comparison block 170, which will be described later, via the line L11.

[Equation 2]

In the above equation (2), m represents the weight of the vehicle, Iz represents the moment of inertia of the vehicle, l represents the wheelbase of the automobile, and Cf and Cr represent the cornering elasticity coefficients of the front wheel and the rear wheel, respectively.

On the other hand, the second lateral acceleration calculation block 130 calculates lateral acceleration of the transient state based on the detected steering angle velocity signal and the vehicle velocity signal provided from the steering angle velocity sensor 114 and the vehicle velocity sensor 116, respectively, The transverse acceleration calculated in the transient state is obtained by differentiating the above-described equation (1), and the transient transverse acceleration calculated here is provided to the laterally-described acceleration comparison block 170 via a line L13. In this case, the transient state means that the driver performs the steep steering in order to avoid a momentary danger during the driving of the vehicle.

Next, in the lateral acceleration comparison block 170, the steady-state lateral acceleration provided by the above-described first lateral acceleration calculation block 130 via the line L11 and the steady-state lateral acceleration provided by the second lateral acceleration calculation block 150 The maximum lateral acceleration a _ymax is determined, for example, as shown in Fig. 3A, using the following equation based on the provided transient lateral acceleration.

[Equation 3]

a _ymax = Max (| steady state transverse acceleration |, transient transverse acceleration |)

In this case, the damping coefficient value according to the maximum lateral acceleration shown in FIG. 3A takes into consideration the stability in which the control effect of the roll motion is great, and the lateral acceleration range is set to be between 0.1 g and 0.5 g. Is a lateral acceleration region which can be operated at the maximum. At this time, the lateral acceleration 1 g is 9.8 m / s ² . However, in the present invention, the lateral acceleration is not necessarily limited to the range from 0.1 g to 0.5 g, but this is only shown as a preferred embodiment. Such a lateral acceleration range may be varied in various degrees depending on various external factors or the like have.

In addition, in the lateral acceleration comparison block 170, the damping coefficient of the front shock absorber and the rear shock shock absorber are appropriately distributed using the maximum lateral acceleration obtained through the above equation, and the front wheel and rear wheel shock absorbers The damping coefficient is provided to the damping coefficient determination block 190 of the next stage. That is, when the absolute value of the lateral acceleration is large, the damping coefficient is distributed so that the damping coefficient of each shock absorber can be increased so as to suppress the rolling motion of the vehicle, thereby ensuring the stability of the vehicle.

Further, in the lateral acceleration comparison block 170, an absolute value difference obtained by subtracting the steady state lateral acceleration absolute value on the line L11 from the transient state lateral acceleration absolute value on the line L13 is calculated. The absolute value difference signal thus calculated is also damped Is provided to a coefficient determination block 190.

On the other hand, in order to improve the stability of the vehicle, the damping coefficient determination block 190 determines the damping coefficients of the front and rear wheels based on the attenuation coefficients of the front wheel and the rear wheel shock absorber provided in the lateral acceleration comparison block 170 And the damping coefficient is adaptively determined on the basis of the absolute value difference signal provided by the lateral acceleration comparison block 170 for improving the adjustment of the vehicle, that is, for example, as shown in FIG. 3B, If the difference in absolute value of acceleration is large, the steering characteristic of the vehicle is oversteer to improve the controllability of the transient state. If the difference in the absolute value of the lateral acceleration is small, it is determined that the vehicle is traveling on a general curve road, . That is, since the difference in the absolute value of the lateral acceleration is large, it means that the driver has urgently performed the steering input to avoid the momentary danger. Therefore, in the damping coefficient determination block 190, The damping coefficients of the front and rear wheels are determined so as to improve the adjustability. A graph of the front-wheel and rear-wheel shock absorber damping ratios by the absolute value difference of the lateral acceleration is shown in FIG. 3B as an example.

More specifically, in the damping coefficient determination block 190, when the absolute value difference signal of the lateral acceleration is small, the shock absorber damping coefficients of the front wheel and the rear wheel are determined to be the same and the front wheel and the rear wheel shock absorber And when the absolute value difference signal of the lateral acceleration is large, the damping coefficient of the rear wheel shock absorber is made larger than the damping coefficient of the front wheel shock absorber to oversteer the inherent steering characteristic of the automobile, thereby improving the adjustment in the emergency steering situation .

Next, a process of controlling the rolling of a running vehicle using the above-described rolling control apparatus of the present invention will be described.

2 is a flowchart illustrating a process of controlling rolling by controlling a damping coefficient of a shock absorber based on a lateral acceleration calculated based on a steering angle signal, a steering angle velocity signal, and a vehicle speed signal according to the present invention.

2, when the steering angle signal, the steering angle velocity signal, and the vehicle speed signal detected through the sensing block 110 are inputted during the running of the automobile (step 202), the steering angle signal and the vehicle speed signal The lateral acceleration of the transient state is calculated based on the detected steering angle velocity signal and the vehicle speed signal (step 204).

Next, the maximum lateral acceleration is calculated based on the calculated steady-state lateral acceleration and transient lateral acceleration (step 206), and the damping coefficients of the front wheel and the rear wheel shock absorber are respectively determined based on the maximum lateral acceleration calculated here (Step 208). At this time, the damping coefficient of the front wheel shock absorber and the rear wheel shock absorber are appropriately distributed using the maximum lateral acceleration. The damping coefficient of the front wheel and the rear wheel shock absorber distributed here is, So that the damping coefficient of the absorber can be increased so that the roll motion of the automobile can be suppressed and the stability of the automobile can be ensured.

Then, the absolute value difference between the calculated steady state lateral acceleration and the transient lateral acceleration is calculated (step 210), and the magnitude of the calculated absolute value difference value is calculated based on the characteristic graph as shown in FIG. 3B (Step 212).

If it is determined that the absolute value of the lateral acceleration is relatively small, it is determined that the vehicle is not an emergency steering for risk avoidance in an unexpected situation, so that the shock absorber damping coefficients of the front wheel and the rear wheel are determined to be the same, The damping coefficient of the front wheel and the rear wheel shock absorber is determined to be equal to the steering characteristic (step 214), and the front wheel and the rear wheel shock absorber are controlled according to the determined damping coefficient (step 218).

On the other hand, if it is determined in step 212 that the absolute value of the lateral acceleration is relatively large, it is determined that the vehicle is an emergency steering for risk avoidance in an unexpected situation, and the shock absorber damping coefficient of the rear wheel is made larger than the damping coefficient of the front wheel (Step 216). By making the damping coefficient thus determined oversteer the inherent steering characteristic of the automobile, the adjustment in the emergency situation is smoothly improved (step 218).

As described above, according to the present invention, the lateral acceleration is calculated on the basis of the steering angle, the steering angle speed, and the vehicle speed of a running vehicle, and when the calculated lateral acceleration is large, the damping coefficient of the shock absorber is increased, It is possible to improve the stability of the vehicle by suppressing the oversteering characteristic of the transient state. Further, when the transverse acceleration in the transient state is larger than the lateral acceleration in the steady state, It is possible to improve the property.

Claims (8)

An apparatus for controlling roll motion generated during running of a vehicle by controlling front wheel shock absorbers and rear wheel shock absorbers respectively mounted on an automobile, A sensing block that detects a steering angle of the steering wheel during driving of the vehicle, detects a steering angle speed of the steering wheel, and detects a vehicle speed of a running vehicle; A first lateral acceleration calculation block for calculating a steady state lateral acceleration of the automobile based on the detected steering angle signal and the detected vehicle speed signal; A second lateral acceleration calculation block for calculating the transient lateral acceleration of the automobile based on the detected steering angle velocity signal and the detected vehicle velocity signal; Calculates the maximum lateral acceleration based on the calculated steady state lateral acceleration and the calculated transient lateral acceleration, assigns the damping coefficients of the front wheel and the rear wheel shock absorber, respectively, on the basis of the calculated maximum lateral acceleration, A lateral acceleration comparison block for calculating an absolute value difference between the steady state lateral acceleration and the calculated transient lateral acceleration; And And a damping coefficient determination block for adaptively determining respective damping coefficients of the front wheel and the rear wheel shock absorber on the basis of the respective damping coefficients of the front wheel and the rear wheel shock absorber and the calculated absolute difference of lateral acceleration, Rolling control device. The vehicle according to claim 1, wherein the steady state lateral acceleration ((a _delta / delta) _ss ) is calculated using the lateral acceleration transfer function (a _delta / delta) A rolling control device of a car. (In the above equation, δ denotes the input steering angle, a _{δ is the} lateral acceleration, T ₁ and T ₂ are time constants, ζ is the damping coefficient, and Wn is the natural frequency of the vehicle.) (Where m is the weight of the car, Iz is the moment of inertia of the car, l is the weight of the car, and Cf and Cr are the cornering modulus of the front and rear wheels, respectively.) The rolling control apparatus for an automobile according to claim 2, wherein the transient lateral acceleration is calculated by differentiating the transverse acceleration transfer function ( _? /?). The damping coefficient determining block according to claim 1, 2 or 3, wherein the damping coefficient determining block determines whether or not the damping coefficient determining block determines that the greater the absolute value of the calculated lateral acceleration between the minimum value and the maximum value of the predetermined absolute difference in lateral acceleration, And the coefficient is assigned gradually larger than the damping coefficient of the front wheel shock absorber. A method of controlling roll motion generated during running of a vehicle by controlling front wheel shock absorbers and rear wheel shock absorbers respectively mounted on an automobile, Detecting a steering angle signal, a steering angle velocity signal, and a vehicle speed signal of a vehicle during driving; Calculating a steady state lateral acceleration of the automobile based on the detected steering angle signal and the detected vehicle speed signal and calculating a transient lateral acceleration of the automobile based on the detected steering angle speed signal and the detected vehicle speed signal; Calculating a maximum lateral acceleration of the automobile on the basis of the calculated steady state lateral acceleration and the calculated transient lateral acceleration; Allocating damping coefficients of the front wheel shock absorber and the rear wheel shock absorber based on the calculated maximum lateral acceleration; Calculating an absolute value difference between the calculated steady state lateral acceleration and the calculated transient state lateral acceleration; And And adaptively determining respective damping coefficients of the front shock absorber and the rear wheel shock absorber based on the respective damping coefficients of the front shock absorber and the rear wheel shock absorber and the calculated absolute difference of lateral acceleration, / RTI > 6. The method according to claim 5, wherein the steady state lateral acceleration ((a _delta / delta) _ss ) is calculated using the following equation using the lateral acceleration transfer function a _delta / delta obtained by the following equation A rolling control method of a vehicle. (In the above equation, δ denotes the input steering angle, a _{δ is the} lateral acceleration, T ₁ and T ₂ are time constants, ζ is the damping coefficient, and Wn is the natural frequency of the vehicle.) (Where m is the weight of the car, Iz is the moment of inertia of the car, l is the weight of the car, and Cf and Cr are the cornering modulus of the front and rear wheels, respectively.) The rolling control method according to claim 6, wherein the transient lateral acceleration is calculated by differentiating the transverse acceleration transfer function ( _? /?). The damping coefficient allocating method according to claim 5, 6, or 7, wherein the damping coefficient allocation is performed such that the greater the absolute value of the calculated lateral acceleration between the minimum value and the maximum value of the predetermined absolute value difference of lateral acceleration, Wherein the coefficient is assigned gradually larger than the damping coefficient of the front wheel suspension unit.