KR101245003B1 - Apparatus for Controlling Coordinate Assist at Dissymmetry Road Surface and Control Method Thereof - Google Patents

Abstract

The present invention relates to a cooperative control apparatus and a control method thereof on an asymmetric friction road surface.

According to an embodiment of the present invention, when braking the vehicle, it is determined whether the asymmetric friction road surface is determined by using the wheel speed received from the wheel speed sensor. A vehicle attitude control device for generating an override angle by applying a low frequency filter to a value, multiplying a value according to the vehicle speed, and adding an offset angle to which a road decision code is applied; And an active front wheel steering apparatus for controlling steering in accordance with an override angle provided from the vehicle attitude control apparatus.

Asymmetric Friction, Cooperative Control, Delta Yaw

Description

Apparatus for Controlling Coordinate Assist at Dissymmetry Road Surface and Control Method Thereof}

An embodiment of the present invention relates to a cooperative control apparatus and a control method thereof on an asymmetric friction road surface. More specifically, the present invention relates to a cooperative control device and a control method on an asymmetrical friction road surface to safely maintain the straight motion of the vehicle without the driver's steering when braking the vehicle on the asymmetric friction road surface.

When braking on a road having an asymmetric frictional force in which ice sheets or the like are formed only at one portion of the left and right wheels, the braking force of the left and right wheels according to the road frictional force is different so that the vehicle is directed toward the roadside frictional force. In order to prevent the vehicle from tipping, in the cooperative control of the conventional active front wheel steering system and the electronically controlled braking device, the yaw rate value and the electronically controlled braking device measured the behavior of the vehicle by the sensor in the electronically controlled braking system. Since the control is performed based only on the delta yaw value, which is a difference between the yaw rate values calculated therein, the yaw motion of the vehicle is large and the difference between the left and right yaw motions is large.

In addition, an unbalance of the control amount occurs depending on how the driver applies the brake. In other words, the momentary braking force of the vehicle is large during sudden braking, and the delta yaw value is large, so that the steer control amount of the vehicle is appropriately generated so that the vehicle can move safely.However, when the brake is applied, the delta yaw value is relatively small. This relatively small size creates a problem that the vehicle is directed to the high friction road surface.

The embodiment of the present invention enables to safely maintain the straight motion of the vehicle without the driver's steering when braking the vehicle on the asymmetric friction road surface.

According to an embodiment of the present invention, when braking the vehicle, it is determined whether the asymmetric friction road surface using the wheel speed received from the wheel speed sensor, and in the case of the asymmetric friction road surface, the delta yaw A vehicle attitude control device for generating an override angle by applying a low frequency filter to an absolute value, multiplying a weight according to a vehicle speed, and adding an offset angle to which a road decision code is applied; And an active front wheel steering apparatus for controlling steering in accordance with an override angle provided from the vehicle attitude control apparatus.

The vehicle attitude control apparatus may include a receiver configured to receive information of a vehicle measured from four wheel speed sensors, a yaw rate sensor, and a steering angle sensor; A determination unit determining whether the current road surface is split mu based on the wheel speed received through the reception unit; Compute the delta yaw by subtracting the yaw rate received by the receiver into the yaw rate calculated internally, calculate the calculated delta yaw and the control angle for the delta yaw, and apply a low frequency filter to the absolute value of the delta yaw. A calculation unit configured to calculate an override angle by multiplying a value obtained by applying the low frequency filter to a weight according to a vehicle speed and adding an offset angle to which a road decision code is applied; And a provision unit for providing the calculated override angle to the active front wheel steering apparatus.

In addition, the vehicle attitude control apparatus may further determine whether the steering angle received from the steering angle sensor is a straight condition in determining whether the vehicle is an asymmetric friction road surface using the wheel speed received from the wheel speed sensor.

In addition, according to another embodiment of the present invention, when braking the vehicle, using the wheel speed received from the wheel speed sensor to determine whether the asymmetric friction road surface; Calculating a control angle for the delta yaw; Calculating an offset angle obtained by applying a low frequency filter to the absolute value of the delta yaw, multiplying a weight according to a vehicle speed, and applying a road decision code to a value to which the low frequency filter is applied; Generating an override angle by adding the offset angle to the control angle; And it provides a cooperative control method comprising the step of controlling the steering in accordance with the override angle.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. If a component is described as being "connected", "coupled" or "connected" to another component, the component may be directly connected to or connected to that other component, but there is another configuration between each component. It should be understood that the elements may be "connected", "coupled" or "connected".

FIG. 1 is a block diagram illustrating a cooperative control apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram illustrating the electronic control braking apparatus illustrated in FIG. 1.

Referring to FIG. 1, a cooperative control apparatus for a vehicle according to an exemplary embodiment of the present invention may be classified into an electronic stability control (ESC) 20 and an active front wheel steering apparatus (AFS). Steering, hereinafter referred to as 'AFS').

Here, the ESC 20 receives the vehicle information from the four wheel speed sensors 11, the yaw rate sensor 12, and the steering angle sensor 13 to generate an override angle. The wheel speed sensor 11 detects the rotation speed of each wheel, the yaw rate sensor 12 detects the yaw rate of the vehicle, and the steering angle sensor 13 detects an input steering angle through the driver's steering wheel.

The AFS 30 receives the steering angle signal and controls the steering driver 32 according to the received steering angle signal. In particular, the AFS 30 controls the steering according to the override angle or the preset override angle threshold provided from the ESC 20 so that the displacement of the pinion occurs.

The ESC 20 determines whether the current road surface is an asymmetric friction road surface (hereinafter referred to as 'split mu') based on the wheel speeds received from the four wheel speed sensors 11. That is, if the rotational speed of the left and right tires differ by more than a certain size, it is determined as split mu. In determining whether the asymmetric friction road surface is obtained using the wheel speed received from the wheel speed sensor 11, it may be further determined whether the steering angle received from the steering angle sensor 13 is a straight condition. In this embodiment, the split mu is determined as the wheel speed, but the present invention is not limited thereto, and the split mu may be determined using a tire pressure sensor.

If the current road surface is split mu, the delta yaw, which is the difference between the yaw rate measured from the yaw rate sensor 12 and the yaw rate calculated inside the ESC 20, is calculated and a control angle (for example, PID control) for the delta yaw is calculated. PID control angle) is applied to the absolute value of the delta yaw, the low frequency filter is applied, the value to which the low frequency filter is applied is multiplied by the weight according to the vehicle speed, and the offset angle to which the road decision code is applied is generated. On the other hand, the vehicle speed can be obtained from the wheel speed received from the wheel speed sensor (11).

On the other hand, the ESC 20 further determines whether the steering angle received from the steering angle sensor 13 is a straight condition in determining whether it is an asymmetric friction road surface using the wheel speed received from the wheel speed sensor 11. That is, if the received steering angle is within a certain size, it is determined that the vehicle is going straight, and at this time, the override angle obtained by adding the PID control angle and the offset angle is obtained.

The calculated override angle is provided to the AFS 30, which is a signal for arbitrarily requesting a steering angle from the AFS 30.

Accordingly, the AFS 30 may control steering in accordance with the override angle provided from the ESC 20 to maintain the straight motion without braking the driver during braking in the split mu, thereby increasing stability of the vehicle.

On the other hand, the pinion angle sensor 14 detects the pinion displacement of the vehicle. The steering angle sensor 13 detects the driver's steering input, while the pinion angle sensor 14 detects the displacement of the actual pinion after steering control is performed by the AFS. The ESC 20 detects the pinion displacement from the pinion angle sensor 14 in a situation where it is not the split mu to perform posture control of the vehicle.

2, the ESC 20 includes a receiver 21, a determiner 22, a calculator 23, and a provider 24.

The receiver 21 receives vehicle information measured from the four wheel speed sensors 11, the yaw rate sensor 12, and the steering angle sensor 13 during braking.

The determination unit 22 determines whether the current road surface is split mu based on the wheel speed received through the reception unit 21. The determination unit 22 may further determine whether the steering angle received from the steering angle sensor 13 is a straight condition in determining whether the asymmetric friction road surface is obtained using the wheel speed received from the wheel speed sensor 11. .

The calculation unit 23 calculates the delta yaw by subtracting the yaw rate received by the receiver 21 to the yaw rate calculated in the ESC 20.

In particular, the calculation unit 23 calculates the override angle through the calculated delta yaw and PID control, and applies a low frequency filter to the absolute angle of the delta yaw to the control angle (for example, PID control angle through PID control) for the delta yaw. Override angle is generated by multiplying the low frequency filter and multiplying the weight according to the vehicle speed and adding the offset angle with the road decision code.

The providing unit 24 provides the calculated override angle to the active front wheel steering apparatus 30.

3 is a graph illustrating delta yaw.

When the delta calculation as shown in the graph of FIG. 3 is calculated, the left and right yaw motion of the vehicle is large when PID control is performed.

The conventional cooperative control apparatus calculates the override angle by the same control method as the PID control from the delta request as shown in the graph of FIG. 3. However, in the present invention, the override angle (hereinafter referred to as PID control angle) by the conventional PID control is calculated. By adding the offset angle, the override angle is calculated and provided to the AFS to reduce the left and right yaw motion of the vehicle during straight braking. That is, the override angle calculated by the cooperative control device of the present invention can be obtained by the formula [Equation 1].

Override angle = PID control angle + offset angle

The offset angle of [Equation 1] is obtained by [Equation 2].

Offset angle = Delta yaw filtering value * Vehicle speed offset gain * Road decision code

The order of obtaining the delta yaw filtering value of Equation 1 is calculated in two steps as follows.

In one step, the absolute value of the delta yaw of FIG.

Step 2 applies a wideband low frequency filter to the delta yaw if the current delta yaw absolute value is greater than the previous delta yaw absolute value, or applies a narrowband low frequency filter to the delta yaw if the current delta yaw absolute value is not greater than the immediately preceding delta yaw value. do. For example, the wide band may be 30 Hz and the narrow band may be 5 Hz.

4 is a graph showing the result of obtaining the delta yaw filter value, and FIG. 5 is a graph illustrating the vehicle speed offset gain.

As shown in FIG. 4, the absolute value is taken from the value of the graph of FIG. 3, and the current delta yaw absolute value is greater than the previous delta yaw absolute value (section A) and the current delta yaw absolute value is greater than the immediately preceding delta yaw absolute value. Divide into smaller sections (Section B). That is, the low frequency filter set so that the cutoff frequency of the A section is greater than the cutoff frequency of the B section.

For example, it can be calculated | required by the low frequency filter formula like the formula of [Equation 3].

Y _k = Y _{k -1} / (1 + a * T) + a * T * U _k / (1 + a * T)

(Y _k : kth filtering value, U _k : kth delta yaw absolute value, a: cutoff frequency, T: sampling period)

As shown in [Equation 3], the equation of the low frequency filter applied to the A section and the B section may vary according to embodiments.

On the other hand, the larger the vehicle speed, the larger the left and right yaw motion of the vehicle, and the smaller the vehicle speed, the smaller the left and right yaw motion of the vehicle is. Therefore, the vehicle speed offset gain is set to have a smaller value as the vehicle speed is larger.

In the present embodiment, it is assumed that the steering angle is directed to the left side to be indicated by a negative sign, and the road decision code indicates that when the left side of the road surface is a low friction road surface and the right side of the road surface is a high friction road surface (- ), If the left side of the road is a high friction road surface and the right side of the road is a low friction road surface, the road decision code becomes (+).

6 is a graph illustrating the calculated PID control angle, offset angle and override angle.

As illustrated in FIG. 6, the override angle obtained by adding the offset angle to the PID control angle is calculated to have a value larger than the PID control angle, thereby reducing the yaw motion of the vehicle.

7 is a flowchart illustrating a cooperative control method according to an embodiment of the present invention.

As shown in FIG. 7, in the cooperative control method according to the exemplary embodiment of the present invention, it is determined whether the vehicle is braking (S702), and whether the asymmetric friction road surface is determined using the wheel speed received from the wheel speed sensor ( In step S704, it is determined whether the steering angle received from the steering angle sensor 13 is a straight condition (S706).

If the determination result is 'Yes', the control angle for the delta yaw is calculated (S708), the low frequency filter is applied to the absolute value of the delta yaw, the weight of the low frequency filter is multiplied according to the vehicle speed, and the road decision code is applied. After the applied offset angle is calculated (S710), the offset angle is calculated by adding the offset angle to the calculated control angle (S712).

If at least one of the determination results of S702, S704, and S706 is 'No', the handling control is performed (S716). That is, the offset angle is calculated to add steering when the vehicle is understeer, and the offset angle is calculated by adding the offset angle to the calculated control angle when the vehicle is understeer. )do.

When the override angle is calculated, it is provided to the AFS to drive the steering driver 32 (S714).

As described above, according to the embodiment of the present invention, there is an effect that can safely maintain the straight motion of the vehicle without the driver's steering when braking the vehicle on the asymmetric friction road surface.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, all of the components may operate selectively in combination with one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. Codes and code segments constituting the computer program may be easily inferred by those skilled in the art.

In addition, the terms "comprise", "comprise", or "having" described above mean that the corresponding component may be embedded unless otherwise stated, and thus, other components. It should be construed that it may further include other components rather than to exclude them. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a block diagram for explaining a cooperative control apparatus according to an embodiment of the present invention,

FIG. 2 is a block diagram illustrating the electronically controlled braking device shown in FIG. 1.

3 is a graph illustrating delta yaw.

4 is a graph showing the results of obtaining a delta yaw filter value.

5 is a graph illustrating the vehicle speed offset gain.

6 is a graph illustrating the calculated PID control angle, offset angle and override angle.

7 is a flowchart illustrating a cooperative control method according to an embodiment of the present invention.

Description of the Related Art

11: wheel speed sensor 12: yaw rate sensor

13: Steering angle sensor 20: ESC

21: receiving unit 22: determining unit

23: calculation unit 24: providing unit

30: AFS 32: Steering Drive

Claims (4)

When braking the vehicle, the wheel speed received from the wheel speed sensor is used to determine whether it is an asymmetric friction road surface, and in the case of an asymmetric friction road surface, a low frequency filter is applied to the control angle for the delta yaw and the absolute value of the delta yaw. A vehicle attitude control device for generating an override angle by multiplying a value obtained by applying a low frequency filter to a weight according to a vehicle speed and adding an offset angle to which a road decision code is applied; And And an active front wheel steering device for controlling steering in accordance with an override angle provided from said vehicle attitude control device. The method of claim 1, The vehicle attitude control device, Receiving unit for receiving information of the vehicle measured from the four wheel speed sensor, yaw rate sensor, steering angle sensor; A determination unit determining whether the current road surface is split mu based on the wheel speed received through the reception unit; Compute the delta yaw by subtracting the yaw rate received by the receiver into the yaw rate calculated internally, calculate the calculated delta yaw and the control angle for the delta yaw, and apply a low frequency filter to the absolute value of the delta yaw. A calculation unit for calculating an overlay angle by multiplying the low frequency filter value by a weight according to a vehicle speed and adding an offset angle to which a road decision code is applied; And Providing unit for providing the calculated override angle to the active front wheel steering device Cooperative control device comprising a. 3. The method according to claim 1 or 2, And the vehicle attitude control device further determines whether the steering angle received from the steering angle sensor is a straight condition in determining whether the vehicle is in an asymmetric friction road surface using the wheel speed received from the wheel speed sensor. Determining whether the vehicle is asymmetrical friction road surface by using the wheel speed received from the wheel speed sensor when braking the vehicle; Calculating a control angle for the delta yaw; Calculating an offset angle obtained by applying a low frequency filter to the absolute value of the delta yaw, multiplying a weight according to a vehicle speed, and applying a road decision code to a value to which the low frequency filter is applied; Generating an override angle by adding the offset angle to the control angle; And Controlling steering according to the override angle Cooperative control method comprising a.

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