Vehicle braking force distribution control device and method thereof

Abstract

The invention provides a vehicle braking force distribution control device. A steering apparatus includes a manipulation unit that selects at least one of a parallel movement mode, a diagonal movement mode, and an in-situ turning mode, a brake pedal detection unit that detects a brake pedal opening value to predict a target deceleration in the parallel movement mode or the diagonal movement mode, and a sensor that outputs steering amount information and longitudinal / lateral deceleration information. The vehicle braking force distribution control apparatus further includes a controller that distributes a braking force of each wheel in a parallel movement mode or a diagonal movement mode according to a target deceleration, corrects the braking force of each wheel based on steering amount information and longitudinal / lateral deceleration information, and allowing the actual braking force of each wheel to track the corrected target braking force in a parallel movement mode or a diagonal movement mode.

Description

TECHNICAL FIELD

[0001] The present application relates to a vehicle braking force distribution control device and a method thereof, and more particularly, to a vehicle braking force distribution control device and a method thereof capable of selectively and variably controlling braking force distribution in driving and braking in a set specific driving mode. BACKGROUND

[0002] In general, since the wheel steering is performed in only two modes (straight and left / right turning), the driver can intuitively drive the vehicle using only a small amount of control system. In contrast, since the four-wheel independent steering system (4WS) independently controls each wheel, it is possible to adjust the vehicle behavior in various ways.

[0003] In a typical front and rear wheel driving mode, the rotation of the wheels corresponds to the rotation of the steering wheel, and the acceleration corresponds to the degree of pressing the accelerator pedal, thereby allowing the vehicle to turn while moving forward. Here, the reverse steering of the rear wheel with respect to the front wheel can be determined based on the vehicle speed or the steering angle, which can help reduce the turning radius during a U-turn.

[0004] In addition, in the diagonal movement mode, the rear wheel is controlled in phase with the front wheel, and the vehicle does not yaw, which is advantageous in a lane change or overtaking scenario.

[0005] In the parallel movement mode, the front and rear wheels can be rotated by 90°, which is advantageous when parallel parking.

[0006] In addition, in the in-place turning mode, the front and rear wheels can be turned by 45°, which allows the vehicle to make a U-turn in a small alley or the like.

[0007] The in-place turning mode is one of the unique driving modes of the 4WS, like the parallel movement mode, and it can attract customers by these unique features. However, the in-place turning mode is a mode in which only the vehicle yaw motion occurs, and the vehicle driver is not familiar with the yaw motion, which can cause discomfort.

[0008] In addition, in the in-place turning mode, since the vehicle motion direction does not match the driver's field of view, the driver must turn the whole body to secure the field of view and drive the vehicle in a state of uncertainty as to when to stop turning, which can increase the difficulty of driving operation and the risk of accidents.

[0009] Considering the dynamic load of the front and rear wheels, the conventional vehicle braking system is designed to distribute the braking force to the front and rear wheels in a ratio of about 6:4. When driving and braking are performed according to the above-mentioned parallel movement mode, diagonal movement mode, and in-place turning mode, the braking force distribution ratio cannot be changed, which can cause unstable vehicle behavior.

[0010] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion can be inferred, that the present information constitutes prior art.

[0011] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it can contain information that does not constitute prior art that is already known in this field. SUMMARY

[0012] The present disclosure is directed to solving the above problems associated with the prior art. An object of the present disclosure is to provide a vehicle brake force distribution control apparatus and method thereof that corrects brake forces of each wheel based on a steering vector and a longitudinal / lateral deceleration and allows actual brake forces of each wheel to track the corrected target brake forces in a parallel movement mode or a diagonal movement mode, thereby ensuring stable behavior of a vehicle in the parallel movement or the diagonal movement mode.

[0013] In one aspect, the present disclosure provides a vehicle brake force distribution control apparatus including a steering unit configured to select at least one of a parallel movement mode, a diagonal movement mode, and a stationary turn mode; a brake pedal detection unit configured to detect a brake pedal opening value to predict a target deceleration in the parallel movement mode or the diagonal movement mode; a sensor configured to generate and output steering vector information and longitudinal / lateral deceleration information according to the brake pedal opening value detected by the brake pedal detection unit; and a controller configured to distribute brake forces of each wheel according to the target deceleration in the parallel movement mode and the diagonal movement mode, correct the brake forces of each wheel based on the steering vector information and the longitudinal / lateral deceleration information output from the sensor, and allow actual brake forces of each wheel to track the corrected target brake forces in the parallel movement mode or the diagonal movement mode.

[0014] In one preferred embodiment, the controller can calculate a variable brake force distribution ratio and a weight transfer ratio of each wheel based on the steering vector information and the longitudinal / lateral deceleration information output from the sensor and correct the brake forces to track the target brake forces according to the calculated variable brake force distribution ratio and the weight transfer ratio.

[0015] In another preferred embodiment, the controller can control an opening value of a hydraulic valve of each wheel for tracking the target brake forces and compare hydraulic information of each wheel detected from the hydraulic valve with target hydraulic information of the target brake forces.

[0016] In yet another preferred embodiment, the controller can repeatedly control the opening value of the hydraulic valve of each wheel to match the hydraulic information with the target hydraulic information.

[0017] In yet another preferred embodiment, the controller can detect current hydraulic information of each wheel for tracking a target braking force, and compare the current hydraulic information with target hydraulic information of the target braking force of each wheel.

[0018] In yet another preferred embodiment, in a case where the current hydraulic information of each wheel exceeds the target hydraulic information, the controller can generate a driving force in the same direction as the vehicle motion direction by controlling the driving motor.

[0019] In a further preferred embodiment, in a case where the current hydraulic information of each wheel is lower than the target hydraulic information, the controller can generate a braking force in the opposite direction to the vehicle motion direction by controlling the driving motor.

[0020] In another further preferred embodiment, in correcting the braking force of each wheel to track the target braking force, the controller can operate to correct a braking force error due to a braking bias.

[0021] In yet another further preferred embodiment, in a case where a yaw value belonging to the yaw rate sensor output of the sensor exceeds a set value, the controller can determine that a braking bias has occurred, and perform feedback control to correct a braking force error of each wheel.

[0022] In yet another further preferred embodiment, in a case where the steering unit switches the driving mode to the cornering-in-place mode, the controller can distribute the braking force of each wheel to be the same.

[0023] In another aspect, the present application provides a method for controlling vehicle braking force distribution, comprising: determining, by a controller, whether a steering unit is manipulated to select at least one of a parallel movement mode, a diagonal movement mode, and a cornering-in-place mode; predicting, by the controller, a target deceleration according to a brake pedal opening value in a case where the steering unit switches the driving mode to the parallel movement mode or the diagonal movement mode; distributing, by the controller, a braking force required for the target deceleration to each wheel in the parallel movement mode or in the diagonal movement mode; and performing control to correct the braking force distributed to each wheel, and allow an actual braking force of each wheel in the parallel movement mode or the diagonal movement mode to track the corrected target braking force.

[0024] In a preferred embodiment, performing control for allowing the actual braking force to track the target braking force can include calculating a variable braking force distribution ratio and a weight transfer ratio of each wheel based on steering amount information and longitudinal / lateral deceleration information output from a plurality of sensors, and correcting the braking force to track the target braking force according to the calculated variable braking force distribution ratio and weight transfer ratio.

[0025] In another preferred embodiment, the control for allowing the actual braking force to track the target braking force can include controlling the opening value of the hydraulic valve of each wheel to track the target braking force, and comparing the hydraulic information of each wheel detected from the hydraulic valve with the target hydraulic information of the target braking force.

[0026] In yet another preferred embodiment, the control for allowing the actual braking force to track the target braking force can include repeatedly controlling the opening value of the hydraulic valve of each wheel so that the hydraulic information matches the target hydraulic information.

[0027] In yet another preferred embodiment, the control for allowing the actual braking force to track the target braking force can include detecting the current hydraulic information of each wheel for tracking the target braking force, and comparing the current hydraulic information with the target hydraulic information of the target braking force of each wheel.

[0028] In yet another preferred embodiment, the control for allowing the actual braking force to track the target braking force can include, in the case where the current hydraulic information of each wheel exceeds the target hydraulic information, generating a driving force in the same direction as the direction of movement of the vehicle by controlling the driving motor.

[0029] In a further preferred embodiment, the control for allowing the actual braking force to track the target braking force can include, in the case where the current hydraulic information of each wheel is lower than the target hydraulic information, generating a braking force in the opposite direction to the direction of movement of the vehicle by controlling the driving motor.

[0030] In another further preferred embodiment, the method can further include correcting, by the controller, a braking force error due to a braking bias when correcting the braking force of each wheel to track the target braking force.

[0031] In yet another further preferred embodiment, the control for allowing the actual braking force to track the target braking force can include, in the case where a yaw value belonging to a yaw rate sensor output of a sensor exceeds a set value, determining that a braking bias has occurred, and performing feedback control for correcting a braking force error of each wheel.

[0032] In yet another further preferred embodiment, performing the braking force distribution for the respective wheels can include distributing the braking force so that the braking force of the respective wheels is the same in the case where the steering unit switches the driving mode to the cornering-in-place mode.

[0033] Other aspects and preferred embodiments of the present application are discussed below.

[0034] It should be understood that the term "vehicle" or "car" or other similar terms used herein include general motor vehicles such as passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including various ships, aircraft, and the like, and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen powered vehicles, and other alternative fuel vehicles (e.g., fuel from resources other than petroleum). As described herein, a hybrid vehicle is a vehicle having two or more power sources, for example, a vehicle driven by both electricity and gasoline.

[0035] The above and other features of the present application are discussed below. BRIEF DESCRIPTION OF DRAWINGS

[0036] The above and other features of the present application will be described in detail below with reference to certain exemplary embodiments of the present application, which are illustrated in the accompanying drawings, given by way of example only, and thus are not limiting the present application, and wherein:

[0037] Figure 1 is a diagram showing a vehicle brake force distribution control device according to a first embodiment of the present application;

[0038] Figure 2 is a diagram showing a vehicle brake force distribution control device according to a second embodiment of the present application;

[0039] Figures 3A to 3C is a diagram showing a parallel movement mode, a diagonal movement mode, and a cornering-in-place mode in a vehicle brake force distribution control device according to an embodiment of the present application;

[0040] Figure 4 is a diagram showing an example of target brake force tracking in a vehicle brake force distribution control device according to the first embodiment of the present application;

[0041] Figure 5 is a diagram showing an example of target brake force tracking in a vehicle brake force distribution control device according to the first embodiment of the present application;

[0042] Figure 6 is a diagram showing an example of target brake force tracking in a vehicle brake force distribution control device according to the first embodiment of the present application;

[0043] Figure 7 is a diagram showing an example of target brake force tracking in a vehicle brake force distribution control device according to the first embodiment of the present application;

[0044] Figures 8A to 8C is a diagram showing an example of target brake force tracking in a vehicle brake force distribution control device according to the second embodiment of the present application;

[0045] Figure 9 This is a diagram illustrating an example of braking deviation in a vehicle brake force distribution control device according to an embodiment of the present invention;

[0046] Figure 10 This is a diagram illustrating an example of braking deviation in a vehicle brake force distribution control device according to an embodiment of the present invention;

[0047] Figure 11 This is a diagram showing a vehicle braking force distribution control method according to another embodiment of the present invention;

[0048] Figure 12 This is a diagram illustrating a first example of a vehicle braking force distribution control method according to another embodiment of the present invention;

[0049] Figure 13 This is a diagram illustrating a second example of a vehicle braking force distribution control method according to another embodiment of the present invention; and

[0050] Figure 14 This is a diagram illustrating brake deviation correction in a vehicle brake force distribution control method according to another embodiment of the present invention.

[0051] It should be understood that the accompanying drawings are not necessarily drawn to scale, and therefore present a somewhat simplified representation of various preferred features illustrating the basic principles of the invention. Specific design features of the invention disclosed herein, such as specific dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and environment of use.

[0052] In the accompanying drawings, and throughout the various figures, reference numerals refer to the same or equivalent parts of the invention. Detailed Implementation

[0053] Various embodiments of the invention will be described in detail below, examples of which are illustrated in the accompanying drawings and described in detail below. While the invention will be described in conjunction with exemplary embodiments, it should be understood that this specification is not intended to limit the invention to these exemplary embodiments. Rather, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments within the spirit and scope of the invention.

[0054] The same reference numerals are used throughout the drawings and accompanying written description to indicate the same or similar components. As used herein, the term "includes" and its variants are intended to cover non-exclusive inclusions such that a process, method, system, product, or apparatus that includes items such as a list of items "includes" items from the list even if not all items are present. As used herein, the terms "another" and "one" are defined as including one or more than one. As used herein, the term "exemplary" is used in the sense of an example, and not the sense of being the best or only example.

[0055] Figure 1 is a diagram illustrating a vehicle brake force distribution control device according to a first embodiment of the present application, Figure 2 is a diagram illustrating a vehicle brake force distribution control device according to a second embodiment of the present application, and Figures 3A to 3C is a diagram illustrating a parallel movement mode, a diagonal movement mode, and a turning-in-place mode for a vehicle brake force distribution control device according to an embodiment of the present application.

[0056] Figure 4 and Figure 7 is a diagram illustrating an example of target brake force tracking in a vehicle brake force distribution control device according to a first embodiment of the present application, Figures 8A to 8C is a diagram illustrating an example of target brake force tracking in a vehicle brake force distribution control device according to a second embodiment of the present application, and Figure 9 and Figure 10 is a diagram illustrating an example of brake bias in a vehicle brake force distribution control device according to an embodiment of the present application.

[0057] As Figure 1 and Figure 2 illustrated, a vehicle brake force distribution control device according to the present embodiment includes a steering unit 100, a brake pedal detection unit 200, a sensor 300, and a controller 400.

[0058] The steering unit 100 is provided to select a specific drive mode, and more specifically, as Figures 3A to 3C illustrated, to select one of a parallel movement mode, a diagonal movement mode, or a turning-in-place mode.

[0059] Vehicles currently in production are generally designed with greater front wheel brake force than rear wheel brake force due to increased front wheel load during braking caused by load shift, prevention of advanced locking of the rear wheels, and the like.

[0060] For example, the brake force ratio of the front wheels to the rear wheels is initially set to 6:4, and as the vehicle deceleration increases, the front wheel brake force increases from the initial ratio.

[0061] Accordingly, in a vehicle having the above-described brake force ratio, in a case where one of the parallel movement mode, the diagonal movement mode, and the in-place turning mode is selected by manipulating the manipulation unit 100, the behavior of the vehicle can become unstable.

[0062] That is, in a case where a vehicle equipped with a brake system in which the brake force ratio of the front wheels to the rear wheels is set to 6:4 travels in a specific drive mode such as the parallel movement mode, the diagonal movement mode, or the in-place turning mode, the right side or the left side of the vehicle becomes the front wheel side or the rear wheel side, and thus, in the case of braking in the parallel movement mode, for example, the vehicle can turn due to a difference between the left and right brake forces of the front and rear wheels, thereby making the behavior of the vehicle unstable.

[0063] Likewise, in the case of braking in the diagonal movement mode, the vehicle can turn due to a difference between the left and right brake forces caused by front and rear weight transfer and left and right weight transfer, thereby making the behavior of the vehicle unstable. In addition, in the case of braking in the in-place turning mode, the center of rotation of the vehicle moves to the rear wheels due to a difference between the brake forces of the front and rear wheels, thereby making the behavior of the vehicle unstable.

[0064] In this regard, according to the present embodiment, by switching the drive mode of the vehicle to a specific drive mode such as the parallel movement mode, the diagonal movement mode, or the in-place turning mode through the manipulation unit 100, it is possible to selectively control the brake force to address the above-described problems.

[0065] To this end, the brake pedal detection unit 200 detects a brake pedal opening value to predict a target deceleration in the parallel movement mode or the diagonal movement mode.

[0066] In addition, the sensor 300 generates and outputs steering vector information and longitudinal / lateral deceleration information according to the brake pedal opening value detected by the brake pedal detection unit 200.

[0067] The sensor 300 can include a steering angle sensor (SAS) 310 for generating and outputting the steering vector information, and a G sensor 320 for generating and outputting the longitudinal / lateral deceleration information.

[0068] The controller 400 allocates the brake force of each wheel in the parallel movement mode or the diagonal movement mode according to the target deceleration, corrects the brake force of each wheel based on the steering vector information and the longitudinal / lateral deceleration information output from the sensor 300, and allows the actual brake force of each wheel to track the corrected target brake force in the parallel movement mode or the diagonal movement mode.

[0069] More specifically, in a case where the drive mode input from the manipulation unit 100 is switched to the parallel movement mode or the diagonal movement mode, the controller 400 predicts a target deceleration of the vehicle from a brake pedal opening value detected by the brake pedal detection unit 200, corrects the detected brake force of each wheel based on the steering angle information and the longitudinal / lateral deceleration information output from the sensors 300 and the G sensor 320, and allows the actual brake force of each wheel to track the corrected target brake force.

[0070] For example, in the parallel movement mode, in a case where the vehicle moves in parallel to the right, since the left front wheel functions as a rear wheel in the parallel movement mode, the controller 400 reduces the brake force to the same level as the left rear wheel. Similarly, since the right rear wheel functions as a front wheel, the controller 400 increases the brake force to the same level as the right front wheel. In addition, the controller 400 corrects the brake forces of the left front wheel and the right rear wheel based on the steering angle information and the longitudinal / lateral deceleration information, and causes the hydraulic pressure for supplying the brake force of each wheel to track the target hydraulic pressure set for the target brake force by feedforward control of the hydraulic valve 10 (see, for example, Figure 1 ).

[0071] Here, in correcting the brake force as described above, the controller 400 calculates a variable brake force distribution ratio and a weight transfer ratio of each wheel based on the steering angle information and the longitudinal / lateral deceleration information output from the steering angle sensor 310 and the G sensor 320, and corrects the brake force in accordance with the calculated variable brake force distribution ratio and the weight transfer ratio to track the target brake force of each wheel.

[0072] That is, in the parallel movement mode in the direction indicated by the arrow in Figure 4 , the brake force distribution ratio of the right front wheel to the left rear wheel is set to, for example, 6:4, which is similar to the initial distribution ratio determined by the vehicle specifications, but when the drive mode is switched to the parallel movement mode, the brake force distribution of the left front wheel and the right rear wheel is determined by the variable brake force distribution ratio.

[0073] In other words, the brake force distribution of the left front wheel can be determined by "variable brake force distribution ratio = initial front wheel brake force distribution ratio * cos(steering angle) + initial rear wheel brake force distribution ratio * sin(steering angle)", and the brake force distribution of the right rear wheel can be determined by "variable brake force distribution ratio = initial front wheel brake force distribution ratio * sin(steering angle) + initial rear wheel brake force distribution ratio * cos(steering angle)".

[0074] Referring to Figure 6, the front-rear and left-right weight transfer ratios can be determined as "front-rear weight transfer (A) = L2*g + a*h / L2*g" and "left-right weight transfer (B) = t*g + 2*β*h / t*g" (g: gravitational acceleration, a: longitudinal deceleration, β: lateral deceleration, h: vehicle height), respectively. In this case, in the parallel movement mode in the direction indicated by Figure 4 As the right weight transfer ratio is greater than the left weight transfer ratio, the right front wheel weight transfer ratio and the left front wheel weight transfer ratio can be determined as A*B and A / B, respectively, and the right rear wheel weight transfer ratio and the left rear wheel weight transfer ratio can be determined as 1 / (A*B) and B / A, respectively.

[0075] Here, the above expressions are merely examples and are not fixed formulas. Other expressions for determining the corrected brake force can be applied.

[0076] That is, in the parallel movement mode, for example, assuming that the brake force ratio of the right wheel to the rear wheel is set to 6:4, since the right wheel becomes the front wheel, the left front wheel and the right rear wheel are corrected according to the variable brake force distribution ratio (see Figure 4 ), and are corrected according to the weight transfer ratio of each wheel (see Figure 5 ), so that the brake force of each wheel can be determined by the combination of the corrected brake forces.

[0077] Similarly, in the diagonal movement mode in which the vehicle moves in the direction indicated by Figure 5 , the brake force distribution of the left front wheel can be determined by "variable brake force distribution ratio = initial front wheel brake force distribution ratio*cos(steering angle) + initial rear wheel brake force distribution ratio*sin(steering angle)", and the brake force distribution of the right rear wheel can be determined by "variable brake force distribution ratio = initial front wheel brake force distribution ratio*sin(steering angle) + initial rear wheel brake force distribution ratio*cos(steering angle)".

[0078] Referring to Figure 6 , the front-rear and left-right weight transfer ratios can be determined as "front-rear weight transfer (A) = L2*g + a*h / L2*g" and "left-right weight transfer (B) = t*g + 2*β*h / t*g" (g: gravitational acceleration, a: longitudinal deceleration, β: lateral deceleration, h: vehicle height), respectively. In Figure 5 the diagonal movement mode in the direction indicated by , since the brake force of the right front wheel is the greatest and the brake force of the left rear wheel is the smallest according to the weight transfer ratio, the right front wheel weight transfer ratio and the left rear wheel weight transfer ratio are determined as A*B and 1 / (A*B), respectively, and the left front wheel weight transfer ratio and the right rear wheel weight transfer ratio are determined as A / B and B / A, respectively.

[0079] Here, the above expressions are merely examples and are not fixed formulas. Other expressions for determining the corrected brake force can be applied.

[0080] That is, in the diagonal movement mode, for example, assuming that the brake force ratio of the right wheel to the rear wheel is set to 6:4, since the brake force distribution of the left front wheel and the right rear wheel is corrected first according to the variable brake force distribution ratio and second according to the weight shift ratio of each wheel, the brake force of each wheel can be determined by the combination of the continuously corrected brake forces.

[0081] As described above, in the parallel movement mode or the diagonal movement mode, in the case where the brake force of each wheel is corrected according to the variable brake force distribution ratio and the weight shift ratio, respectively, the controller 400 controls the opening value of the hydraulic valve 10 of each wheel according to the corrected brake force to track the target brake force, and compares the hydraulic information of each wheel detected from the hydraulic valve 10 with the target hydraulic information of the target brake force.

[0082] Here, the controller 400 repeatedly controls the opening value of the hydraulic valve 10 of each wheel so that the hydraulic information matches the target hydraulic information, thereby performing feedforward control to make the hydraulic pressure of each wheel track the target hydraulic pressure, and thus, the stability of the vehicle when braking in the parallel movement mode or the diagonal movement mode can be improved.

[0083] In addition to the above control of the hydraulic valve 10, for a vehicle not equipped with an electric booster, as shown in FIG. 7, the controller 400 according to the present embodiment can allow the actual brake force of each wheel to track the corrected target brake force in the parallel movement mode or the diagonal movement mode under the control of the drive motor 20. Figure 2

[0084] That is, the controller 400 can operate to apply only driving force or brake force to a specific target wheel. To this end, the controller 40 detects the current hydraulic information of each wheel for tracking the target brake force through the hydraulic detection unit 30 (see FIG. 1), and compares the current hydraulic information of each wheel with the target hydraulic information of the target brake force. Figure 2

[0085] Here, in the case where the current hydraulic pressure of each wheel exceeds the target hydraulic pressure, the controller 400 controls the drive motor 20 to generate driving force in the same direction as the direction of movement of the vehicle, and in the case where the current hydraulic pressure of each wheel is lower than the target hydraulic pressure, the controller 400 controls the drive motor 20 to generate driving force in the opposite direction to the direction of movement of the vehicle.

[0086] For example, as shown in FIG. 8, the controller 400 according to the present embodiment can control the drive motor 20 to generate driving force in the same direction as the direction of movement of the vehicle in the case where the current hydraulic pressure of each wheel exceeds the target hydraulic pressure, and in the case where the current hydraulic pressure of each wheel is lower than the target hydraulic pressure, the controller 400 controls the drive motor 20 to generate driving force in the opposite direction to the direction of movement of the vehicle. Figure 8A ​​As shown, in the parallel movement mode in which the vehicle moves to the right, the right front wheel braking force and the left rear wheel braking force can be determined according to the initial distribution ratio determined according to the vehicle specifications, but since the left front wheel becomes the rear wheel and the right rear wheel becomes the front wheel according to the vehicle movement direction, the braking forces must be selectively changed.

[0087] Therefore, for a vehicle equipped with a driving motor 20 corresponding to the in-wheel motor, as Figure 8B As shown, in the case where the current hydraulic pressure of the left front wheel exceeds the target hydraulic pressure, the controller 400 controls the driving motor 20 to generate a driving force in the same direction as the vehicle movement direction, and in the case where the current hydraulic pressure of the right rear wheel is less than the target hydraulic pressure, controls the driving motor 20 to generate an additional driving force in the opposite direction to the vehicle movement direction, so that the same braking force can be finally generated for the changed front and rear wheels, as Figure 8C As shown.

[0088] In correcting the braking force of each wheel to track the target braking force as described above, the controller 400 can operate to correct the braking force error due to the braking deviation.

[0089] That is, in the case where the vehicle moves according to the steering angle detected by the steering angle sensor 310, the controller 400 determines that the braking deviation occurs in the case where the yaw value detected by the yaw rate sensor 330 belonging to the sensor 300 exceeds the set value, and performs feedback control for correcting the braking force error of each wheel.

[0090] More specifically, even if the left braking force and the right braking force are the same, for example, in the case where the weight distribution of the vehicle differs greatly from the set value, in the case where the road or the road friction is uneven, or in the case where the performance of the braking system differs greatly from the set value due to overheating or the like, etc., differential braking can occur.

[0091] For example, in the parallel movement mode or the diagonal movement mode, as Figure 9 As shown, in the case where the center of gravity (A) of the vehicle is biased to the front side of the vehicle, or as Figure 10 As shown, in the case where the braking force of each wheel is controlled to track the target braking force, but the braking force of any one wheel does not reach the target braking force level, the vehicle can spin during the travel and braking in the parallel movement mode or the diagonal movement mode.

[0092] Thus, in a case where the yaw value exceeds the set value, the controller 400 determines that an unexpected vehicle behavior, i.e., differential braking, has occurred during braking in the parallel movement mode or the diagonal movement mode, and performs feedback control to reduce the braking force error with respect to the target braking force, and thus, even in the differential braking state as described above, it is possible to effectively ensure the stability of the vehicle behavior.

[0093] As described above, the controller 400 can perform braking force distribution in the spot turn mode as well as in the parallel movement mode or the diagonal movement mode.

[0094] That is, in a case where the steering unit 100 switches the drive mode to the spot turn mode, the controller 400 can distribute the braking force of each wheel to be the same. For example, assuming that the total required braking force is 20, the controller 400 can operate to distribute the braking force of 5 to each wheel, as Figure 7 indicated.

[0095] Figure 11 is a diagram sequentially showing a vehicle braking force distribution control method according to another embodiment of the present application, Figure 12 is a diagram showing a first example of the vehicle braking force distribution control method according to this embodiment.

[0096] Figure 13 is a diagram showing a second example of the vehicle braking force distribution control method according to this embodiment, Figure 14 is a diagram showing a braking bias correction of the vehicle braking force distribution control method according to this embodiment.

[0097] Hereinafter, the vehicle braking force distribution control method according to the present embodiment will be described sequentially with reference to Figure 11

[0098] First, in order to select one of the parallel movement mode, the diagonal movement mode, and the spot turn mode as the drive mode, it is determined by the controller 400 whether or not there is a manipulation by the steering unit 100 (S100).

[0099] For example, in a case where a vehicle equipped with a braking system in which the braking force ratio of the front wheels to the rear wheels is set to 6:4 is driven in a specific driving mode such as the parallel movement mode, the diagonal movement mode, or the spot turn mode, the right side or the left side of the vehicle becomes the front wheel side or the rear wheel side, and thus, when braking in the parallel movement mode, for example, the vehicle can turn due to a difference between the left and right braking forces of the front and rear wheels, and thus, the vehicle behavior can become unstable.

[0100] ​Also, when braking in the diagonal movement mode, the vehicle can rotate due to the difference in braking force between the left and right wheels caused by the front and rear weight shift and the left and right weight shift, thereby destabilizing the behavior of the vehicle. In addition, when braking in the cornering-in-place mode, the center of rotation of the vehicle moves to the rear wheels due to the difference between the front and rear wheel braking forces, thereby destabilizing the behavior of the vehicle.

[0101] To solve this problem, in the present embodiment, when determining whether or not there is a manipulation by the manipulation unit 100, it is determined whether or not the vehicle driving mode is switched to a specific driving mode, such as the parallel movement mode, the diagonal movement mode, or the cornering-in-place mode (S100). In the case where it is determined that the driving mode is switched to the specific mode, the braking force is selectively controlled by the controller 400.

[0102] To this end, in the case where the specific driving mode is selected by the manipulation unit 100 (S100), when the driving mode is switched to the parallel movement mode or the diagonal movement mode as the specific driving mode (S200), the controller 400 predicts the target deceleration from the brake pedal opening value (S300), and performs the braking force distribution to each wheel in the parallel movement mode or the diagonal movement mode (S400).

[0103] For example, in the parallel movement mode, in the case where the vehicle moves in parallel to the right according to the usual front and rear wheel braking force ratio, since the left front wheel functions as the rear wheel in the parallel movement mode, the controller 400 reduces the braking force to the same level as the left rear wheel. Similarly, since the right rear wheel functions as the front wheel, the controller 400 increases the braking force to the same level as the right front wheel.

[0104] Here, the controller 400 performs correction based on the steering angle information and the longitudinal / lateral deceleration information (S500 and S600), and causes the hydraulic pressure for providing the braking force of each wheel to track the target hydraulic pressure of the set target braking force by the feedforward control of the hydraulic valve 10 (S700).

[0105] More specifically, the controller 400 first corrects the braking force of each wheel using the steering angle information output from the steering angle sensor (SAS) 310 (S500), and then corrects the braking force of each wheel using the longitudinal / lateral deceleration information output from the G sensor 320 (S600).

[0106] Here, in Figure 11 In the above, an example in which the first correction (S500) and the second correction (S600) are sequentially performed by the controller 400 is shown, but for the braking force correction, it is preferable to simultaneously perform the first correction (S500) and the second correction (S600).

[0107] Here, the first correction (S500) and the second correction (S600) are simultaneously performed as follows.

[0108] In the parallel movement mode, the braking force distribution ratio of the right front wheel and the left rear wheel is set to, for example, 6:4, similar to the initial distribution ratio determined by the vehicle specifications, but the braking force distribution of the left front wheel and the right rear wheel is determined by the variable braking force distribution ratio.

[0109] In other words, the braking force distribution of the left front wheel can be determined by "variable braking force distribution ratio = initial front wheel braking force distribution ratio * cos (steering angle) + initial rear wheel braking force distribution ratio * sin (steering angle)", and the braking force distribution of the right rear wheel can be determined by "variable braking force distribution ratio = initial front wheel braking force distribution ratio * sin (steering angle) + initial rear wheel braking force distribution ratio * cos (steering angle)".

[0110] Referring to Figure 6 , the front-rear and left-right weight transfer ratios can be determined as "front-rear weight transfer (A) = L2 * g + a * h / L2 * g" and "left-right weight transfer (B) = t * g + 2 * b * h / t * g", respectively (g: gravitational acceleration, a: longitudinal deceleration, b: lateral deceleration, h: vehicle height). In this case, in the parallel movement mode in the direction indicated by Figure 4 , since the right weight transfer ratio is larger than the left weight transfer, the right front wheel weight transfer ratio and the left front wheel weight transfer ratio can be determined as A * B and A / B, respectively, and the right rear wheel weight transfer ratio and the left rear wheel weight transfer ratio can be determined as 1 / (A * B) and B / A, respectively.

[0111] Here, the above expressions are only examples and are not fixed formulas, and other expressions for determining the corrected braking force can be applied.

[0112] That is, in the parallel movement mode, for example, assuming that the braking force ratio of the right wheel and the rear wheel is set to 6:4, since the right wheel becomes the front wheel, the left front wheel and the right rear wheel are corrected according to the variable braking force distribution ratio (see Figure 4 ), and are corrected according to the weight transfer ratio of each wheel (see Figure 5 ), so that the braking force of each wheel can be determined by the combination of the corrected braking forces.

[0113] Similarly, in the diagonal movement mode in which the vehicle moves in the direction indicated by Figure 5 , the braking force distribution of the left front wheel can be determined by "variable braking force distribution ratio = initial front wheel braking force distribution ratio * cos (steering angle) + initial rear wheel braking force distribution ratio * sin (steering angle)", and the braking force distribution of the right rear wheel can be determined by "variable braking force distribution ratio = initial front wheel braking force distribution ratio * sin (steering angle) + initial rear wheel braking force distribution ratio * cos (steering angle)".

[0114] Referring toFigure 6 The front-to-rear and left-to-right weight transfer ratios can be determined as "Front-to-rear weight transfer (A) = L²*g + α*h / L²*g" and "Left-to-right weight transfer (B) = t*g + 2*β*h / t*g" (g: gravitational acceleration, α: longitudinal deceleration, β: lateral deceleration, h: vehicle height). Figure 5 In the diagonal movement mode shown, since the braking force of the right front wheel is the greatest and the braking force of the left rear wheel is the smallest according to the weight transfer ratio, the weight transfer ratio of the right front wheel and the weight transfer ratio of the left rear wheel are determined to be A*B and 1 / (A*B) respectively, and the weight transfer ratio of the left front wheel and the weight transfer ratio of the right rear wheel can be determined to be A / B and B / A respectively.

[0115] The expression above is merely an example and not a fixed formula. Other expressions can be applied to determine the braking force for correction.

[0116] That is, in diagonal movement mode, for example, assuming the braking force ratio of the right wheel to the rear wheel is set to 6:4, since the left front wheel and the right rear wheel are first corrected according to the variable braking force distribution ratio, and then corrected according to the weight transfer ratio of each wheel, the braking force of each wheel can be determined by the combination of continuously corrected braking forces.

[0117] As described above, in parallel movement mode or diagonal movement mode, when the braking force of each wheel is corrected first and second according to the variable braking force distribution ratio and the weight transfer ratio respectively (S500 and S600), such as Figure 12 As shown, the controller 400 calculates the target current for each wheel based on the corrected braking force (S710) and controls the opening value of the hydraulic valve 10 for each wheel to track the target braking force (S720).

[0118] Here, the controller 400 detects hydraulic pressure based on the opening value of the hydraulic valve 10 of each wheel (S730) and compares the hydraulic pressure information of each wheel with the target hydraulic pressure information for the target braking force of each wheel.

[0119] Here, the controller 400 repeatedly controls the opening value of the hydraulic valve 10 for each wheel, so that the hydraulic information matches the target hydraulic information (S740), and performs feedforward control to allow the hydraulic pressure of each wheel to track the target hydraulic pressure, thereby improving the movement stability when braking in parallel movement mode or diagonal movement mode.

[0120] As another embodiment for using braking force to track a target, such as Figure 13 As shown, a method of performing control by comparing current hydraulic information with target hydraulic information for the target braking force can be applied to vehicles without electric power steering.

[0121] That is, the controller 400 can be operated to apply driving force or braking force only to a specific target wheel. To do this, the controller 400 detects the current hydraulic information of each wheel to track the target braking force and compares the current hydraulic information of each wheel with the target hydraulic information of the target braking force.

[0122] Here, when the current hydraulic pressure of each wheel exceeds the target hydraulic pressure (S710-1), the controller 400 determines that the motor driving force of the corresponding wheel should be generated (S712-1), calculates the target current for controlling the generation of the driving force of the drive motor 20 (S714-1), and generates the driving force in the same direction as the vehicle's direction of movement (S716-1).

[0123] When the current hydraulic pressure of each wheel is less than the target hydraulic pressure (S710-2), the controller 400 determines that the corresponding wheel's electric motor power should be generated (S712-2), calculates the target current for generating the braking force of the drive motor 20 (S714-2), and generates the braking force in the direction opposite to the vehicle's direction of movement (S716-2).

[0124] For example, such as Figure 8A As shown, in the parallel movement mode where the vehicle is moving to the right, the braking force of the right front wheel and the braking force of the left rear wheel can be determined according to the initial distribution ratio determined by the vehicle specifications. However, since the left front wheel becomes the rear wheel and the right rear wheel becomes the front wheel depending on the direction of movement, the braking force must be selectively changed.

[0125] Therefore, for vehicles equipped with drive motors 20 corresponding to in-wheel motors, such as Figure 8B As shown, when the current hydraulic pressure of the left front wheel exceeds the target hydraulic pressure, the controller 400 controls the drive motor 20 to generate a driving force in the same direction as the vehicle's movement. Conversely, when the current hydraulic pressure of the right rear wheel is less than the target hydraulic pressure, the controller controls the drive motor 20 to generate an additional driving force in the opposite direction to the vehicle's movement. This ultimately enables the generation of the same braking force for both the front and rear wheels. Figure 8C As shown.

[0126] When correcting the braking force of each wheel as described above to track the target braking force, the controller 400 can operate to correct braking force errors caused by braking deviations, such as... Figure 14 As shown.

[0127] That is, in a case where the vehicle moves according to the steering angle detected by the steering angle sensor 310, in a case where the yaw value detected by the yaw rate sensor 330 belonging to the sensor 300 exceeds a set value (S810), the controller 400 determines that a brake deviation has occurred (S820), and performs feedback control by correcting the hydraulic pressure of the hydraulic valve 10 to correct the brake force error of each wheel (S830).

[0128] More specifically, even if the left brake force and the right brake force are the same, for example, in a case where the weight distribution of the vehicle differs greatly from a set value, in a case where the road or the road friction is uneven, or in a case where the performance of the brake system differs greatly from a set value due to overheating, etc., a differential braking can occur.

[0129] For example, in the parallel movement mode or the diagonal movement mode, as shown in FIG. 6, in a case where the center of gravity (A) of the vehicle is biased to the front side of the vehicle, or as shown in FIG. 7, in a case where the brake force of each wheel is controlled to track the target brake force, but the brake force of any one wheel does not reach the target brake force level, the vehicle can spin during traveling and braking in the parallel movement mode or the diagonal movement mode. Figure 9 Figure 10

[0130] Therefore, in a case where the yaw value exceeds the set value (S810), the controller 400 determines that an unexpected vehicle behavior, i.e., a differential braking, has occurred during braking in the parallel movement mode or the diagonal movement mode (S820), and performs feedback control by hydraulic pressure correction of each wheel to reduce the brake force error with respect to the target brake force (S830), so that the stability of the vehicle behavior can be effectively ensured even in the differential braking state as described above.

[0131] As described above, the controller 400 can perform brake force distribution in the spot turn mode as well as in the parallel movement mode or the diagonal movement mode.

[0132] That is, in a case where it is determined whether there is a manipulation of the manipulation unit 100 to select one of the parallel movement mode, the diagonal movement mode, and the spot turn mode (S100), for example, in a case where the drive mode is switched to the spot turn mode, the controller 400 can distribute the brake force of each wheel to be the same. For example, assuming that the total required brake force is 20, the controller 400 can operate to distribute the brake force of 5 to each wheel, as shown in FIG. 8. Figure 7

[0133] ​​​According to the present application, the braking force of each wheel can be corrected in accordance with the steering angle and the longitudinal / lateral deceleration in the parallel movement mode or the diagonal movement mode, and the actual braking force can be controlled to track the corrected target braking force, thereby ensuring stable vehicle behavior in a special driving mode such as the parallel movement mode or the diagonal movement mode.

[0134] Further, according to the present application, the braking force distribution can be performed so that the braking force of each wheel is the same in the stationary turning mode, thereby ensuring stable vehicle behavior in a special driving mode such as the stationary turning mode.

[0135] Furthermore, according to the present application, in a variety of cases, a braking force error can occur due to a braking bias when braking in the parallel movement mode or the diagonal movement mode, and in this case, the braking force error of each wheel can be corrected by feedback control, thereby providing optimal braking performance and stable vehicle behavior.

[0136] The present application has been described in detail above with reference to the preferred embodiments according to the present application. However, it will be appreciated by persons skilled in the art that changes can be made to these embodiments without departing from the conception and the spirit of the present application.

Claims

1. A vehicle brake force distribution control device comprising: a steering unit configured to select at least one of a parallel movement mode, a diagonal movement mode, and a cornering-in-place mode; a brake pedal detection unit configured to detect a brake pedal opening value to predict a target deceleration in the parallel movement mode or the diagonal movement mode; a sensor configured to generate and output a steering vector information and a longitudinal / lateral deceleration information according to the brake pedal opening value detected by the brake pedal detection unit; and a controller configured to distribute a brake force of each wheel in the parallel movement mode or the diagonal movement mode according to the target deceleration, correct the brake force of each wheel based on the steering vector information and the longitudinal / lateral deceleration information output from the sensor, and allow an actual brake force of each wheel to track a corrected target brake force in the parallel movement mode or the diagonal movement mode. 2.The device according to claim 1, wherein the controller calculates a variable brake force distribution ratio and a weight transfer ratio of each wheel based on the steering vector information and the longitudinal / lateral deceleration information output from the sensor, and corrects the brake force to track the target brake force according to the calculated variable brake force distribution ratio and the weight transfer ratio. 3.The device according to claim 2, wherein the controller controls an opening value of a hydraulic valve of each wheel for tracking the target brake force, and compares hydraulic information of each wheel detected from the hydraulic valve with target hydraulic information of the target brake force. 4.The device according to claim 3, wherein the controller repeatedly controls the opening value of the hydraulic valve of each wheel so that the hydraulic information matches the target hydraulic information. 5.The device according to claim 2, wherein the controller detects current hydraulic information of each wheel for tracking the target brake force, and compares the current hydraulic information with target hydraulic information of the target brake force of each wheel. 6.The device according to claim 5, wherein in a case where the current hydraulic information of each wheel exceeds the target hydraulic information, the controller generates a driving force in the same direction as a vehicle movement direction by controlling a driving motor. 7.The device according to claim 5, wherein in a case where the current hydraulic information of each wheel is lower than the target hydraulic information, the controller generates the brake force in the opposite direction to the vehicle movement direction by controlling the driving motor. 8.The device according to claim 1, wherein in correcting the brake force of each wheel to track the target brake force, the controller performs control for correcting a brake force error due to a brake bias. 9.The device according to claim 8, wherein In a case where a yaw value belonging to a yaw rate sensor output of the sensor exceeds a set value, the controller determines that the brake deviation has occurred, and performs feedback control to correct the brake force error of each wheel.

10. The apparatus according to claim 1, wherein In a case where the steering unit switches the drive mode to the cornering-in-place mode, the controller distributes the brake force of each wheel to be the same.

11. A vehicle brake force distribution control method, comprising: determining, by a controller, whether a steering unit is steered to select at least one of a parallel movement mode, a diagonal movement mode, and a cornering-in-place mode; in a case where the steering unit switches the drive mode to the parallel movement mode or the diagonal movement mode, predicting, by the controller, a target deceleration according to a brake pedal opening degree value; distributing, by the controller, a brake force of each wheel required for the target deceleration in the parallel movement mode or the diagonal movement mode; and performing, by the controller, control for correcting the brake force distributed to each wheel and allowing an actual brake force of each wheel in the parallel movement mode or the diagonal movement mode to track the corrected target brake force.

12. The method according to claim 11, wherein the step of performing control for allowing the actual brake force to track the target brake force includes calculating a variable brake force distribution ratio and a weight transfer ratio of each wheel based on steering amount information and longitudinal / lateral deceleration information output from a plurality of sensors, and correcting the brake force to track the target brake force according to the calculated variable brake force distribution ratio and the weight transfer ratio.

13. The method according to claim 12, wherein the step of performing control for allowing the actual brake force to track the target brake force includes controlling an opening degree value of a hydraulic valve of each wheel for tracking the target brake force, and comparing hydraulic information of each wheel detected from the hydraulic valve with target hydraulic information of the target brake force.

14. The method according to claim 13, wherein the step of performing control for allowing the actual brake force to track the target brake force includes repeatedly controlling the opening degree value of the hydraulic valve of each wheel so that the hydraulic information matches the target hydraulic information.

15. The method according to claim 12, wherein the step of performing control for allowing the actual brake force to track the target brake force includes detecting current hydraulic information of each wheel for tracking the target brake force, and comparing the current hydraulic information with target hydraulic information of the target brake force of each wheel.

16. The method according to claim 15, wherein the step of performing control for allowing the actual brake force to track the target brake force includes, in a case where the current hydraulic information of each wheel exceeds the target hydraulic information, generating a drive force in the same direction as a vehicle movement direction by controlling a drive motor.

17. The method according to claim 15, wherein The step of executing control for allowing the actual braking force to track the target braking force includes, in a case where the current hydraulic pressure information of each wheel is lower than the target hydraulic pressure information, generating a braking force in a direction opposite to a vehicle motion direction by controlling a drive motor.

18. The method of claim 11, further comprising: correcting, by the controller, a braking force error due to a braking bias when correcting the braking force of each wheel to track the target braking force.

19. The method of claim 11, wherein The step of executing control for allowing the actual braking force to track the target braking force includes, in a case where a yaw value belonging to a yaw rate sensor output of the sensor exceeds a set value, determining that a braking bias has occurred, and executing feedback control to correct the braking force error of each wheel.

20. The method of claim 11, wherein The step of assigning a braking force to each wheel includes, in a case where the steering unit switches the drive mode to the stationary turning mode, assigning the braking force so that the braking force of each wheel is the same.

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