Vehicle braking force distribution control device and method thereof

Abstract

The present invention provides a vehicle braking force distribution control apparatus and method, the vehicle braking force distribution apparatus including: a turning state detection unit that detects whether a vehicle is in a turning state based on a traveling state of the vehicle; a vehicle speed detection unit that detects whether the vehicle speed is equal to or less than a predetermined threshold value; a first yaw moment calculation unit that calculates a first yaw moment on the basis of the traveling state, the vehicle speed, and a first wheelbase of the vehicle, the first wheelbase being a virtual wheelbase of the vehicle; a second yaw moment calculation unit that calculates a second yaw moment on the basis of the traveling state, the vehicle speed, and a second wheelbase on the basis of a unique value of the vehicle; a target torque calculation unit that calculates a target torque on the basis of the difference between the first yaw torque and the second yaw torque; and a braking force distribution control unit that controls the braking force distribution amount of the wheels of the vehicle on the basis of the target torque. When the vehicle turns and the vehicle speed is equal to or less than a predetermined threshold value, the braking force distribution control unit controls the braking force distribution amount of the wheels on the basis of the target torque.

Description

Technical Field

[0001] The invention relates to a vehicle braking force distribution control device and method thereof. Background Art

[0002] In recent years, efforts have been actively made to provide access to sustainable transportation systems that also take into account the disadvantaged positions of traffic participants such as the elderly, the disabled, and children. In order to achieve the above-mentioned goals, research and development efforts are being made to further improve the safety and convenience of traffic through developments related to the behavioral safety of vehicles.

[0003] Patent document 1 discloses the following technology. When the vehicle turns at a low speed when turning in a narrow parking lot, the target pressure of the brake is set according to the accelerator opening, and based on this target pressure, the braking force difference between the left and right wheels of the vehicle is adjusted to a turning radius smaller than the turning radius based on the inherent characteristics of the vehicle.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Publication No. 2008-126858

[0006] In order to further improve the turning performance, in a long wheelbase vehicle, the turning behavior of a short wheelbase vehicle (such as a light car) is taken as an ideal and the vehicle is controlled in a manner close to the ideal turning behavior.

[0007] However, in terms of vehicle behavior safety, how to improve the turning characteristics of long-wheelbase vehicles at low speeds is a problem. Summary of the invention

[0008] This proposal aims to solve the above-mentioned problems and improve the turning characteristics of long-wheelbase vehicles at low speeds. Furthermore, it contributes to the development of sustainable transportation systems.

[0009] According to an embodiment of the present invention, a vehicle braking force distribution device is proposed. The vehicle braking force distribution device includes: a turning state detection unit for detecting whether the vehicle is in a turning state based on the driving state of the vehicle; a vehicle speed detection unit for detecting whether the vehicle speed is equal to or less than a specified threshold; a first yaw moment calculation unit for calculating a first yaw moment based on the driving state, the vehicle speed and the first wheelbase of the vehicle, wherein the first wheelbase is an imaginary wheelbase of the vehicle; a second yaw moment calculation unit for calculating a second yaw moment based on the driving state, the vehicle speed and the second wheelbase based on the inherent value of the vehicle; a target moment calculation unit for calculating a target moment based on the difference between the first yaw moment and the second yaw moment; and a braking force distribution control unit for controlling the braking force distribution amount of the wheels of the vehicle based on the target moment. The braking force distribution control unit controls the braking force distribution amount of the wheels based on the target moment when the vehicle is turning and the vehicle speed is equal to or less than the specified threshold.

[0010] According to an embodiment of the present invention, in the above-mentioned vehicle braking force distribution device, the driving state may include: a steering angle. The vehicle braking force distribution device further includes: a first wheelbase setting unit, which sets the first wheelbase based on the steering angle. When the vehicle is turning and the vehicle speed is below the specified threshold, the first wheelbase setting unit sets the first wheelbase in a manner that the first wheelbase is less than or equal to the second wheelbase, and in a specified interval, the first wheelbase is set in a manner that the greater the current steering angle, the smaller the value of the first wheelbase.

[0011] According to an embodiment of the present invention, in the above-mentioned vehicle braking force distribution device, the first wheelbase has a hysteresis characteristic, and when the steering angle increases, when the steering angle becomes a first threshold, the first wheelbase is set to a minimum value, and thereafter, when the steering angle decreases and becomes less than a second threshold that is smaller than the first threshold, the first wheelbase increases from the minimum value, and is less likely to increase when the steering angle decreases than when the steering angle increases.

[0012] According to an embodiment of the present invention, the vehicle braking force distribution device further includes: an obstacle detection unit for detecting obstacles around the vehicle; a contact judgment unit for judging the possibility of the obstacle contacting the inner side of the turning direction of the vehicle based on the obstacle; and a first wheelbase setting unit for setting the first wheelbase based on the judgment result of the contact judgment unit. When the vehicle is turning and the vehicle speed is equal to or less than the prescribed threshold value, and it is judged that the obstacle is likely to contact the vehicle, the first wheelbase setting unit sets the first wheelbase to a value greater than the current value.

[0013] According to an embodiment of the present invention, in the above-mentioned vehicle braking force distribution device, the driving state includes: a steering angle. The first wheelbase setting unit sets the first wheelbase based on the determination result of the contact determination unit and the steering angle. When the vehicle is turning and the vehicle speed is equal to or less than the predetermined threshold, when the contact determination unit determines that there is a possibility that the obstacle is in contact with the vehicle, the first wheelbase setting unit sets the first wheelbase in such a manner that the first wheelbase is greater than or equal to the second wheelbase, and in a specified interval, the first wheelbase is set in such a manner that the greater the current steering angle, the greater the value of the first wheelbase.

[0014] According to another embodiment of the present invention, a vehicle braking force distribution method is proposed, which includes: detecting whether the vehicle is in a turning state based on the driving state of the vehicle; detecting whether the vehicle speed is equal to or less than a specified threshold value; calculating a first yaw moment based on the driving state, the vehicle speed and a first wheelbase of the vehicle, wherein the first wheelbase is an imaginary wheelbase of the vehicle; calculating a second yaw moment based on the driving state, the vehicle speed and a second wheelbase based on an inherent value of the vehicle; calculating a target torque based on the difference between the first yaw moment and the second yaw moment; and when the vehicle turns and the vehicle speed is equal to or less than a specified threshold value, controlling the braking force distribution amount of the vehicle's wheels based on the target torque.

[0015] According to the above-described embodiment, for example, the turning performance can be improved even when the vehicle turns at a low speed, such as when turning or parking in a narrow parking lot, and even a vehicle with a long wheelbase can be controlled to behave like a vehicle with a short wheelbase. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 2 is a block diagram of a vehicle braking force distribution device according to an embodiment of the present invention.

[0017] Figure 2 is a circuit diagram of a vehicle braking force distribution device according to an embodiment of the present invention.

[0018] Figure 3 4 is a schematic diagram of a situation of vehicle braking force distribution according to an embodiment of the present invention.

[0019] Figure 4 FIG. 2 is an explanatory diagram for explaining the hysteresis characteristic of the first wheelbase according to the embodiment of the present invention.

[0020] Figure 5 This is a diagram showing the steering angle diagram for changing the wheelbase.

[0021] Figure 6 (a) to Figure 6(c) is a schematic diagram of a situation of vehicle braking force distribution according to another embodiment of the present invention.

[0022] Description of Reference Numerals

[0023] 100: Vehicle braking force distribution device

[0024] 102: Turning state detection unit

[0025] 102a: Steering angle diagram

[0026] 104: Vehicle speed detection unit

[0027] 106: First yaw moment calculation unit

[0028] 108: Second yaw moment calculation unit

[0029] 110: Target torque calculation unit

[0030] 112: Braking force distribution control unit

[0031] 112a: Braking force generating wheel selection unit

[0032] 112b: Limiter

[0033] 114: First wheelbase setting unit

[0034] 116: Obstacle Detection Department

[0035] 118: Contact judgment unit

[0036] 120: Control Department

[0037] 130: Steering device

[0038] 140: Braking device DETAILED DESCRIPTION

[0039] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0040] Figure 1 is a block diagram of a vehicle braking force distribution device according to an embodiment of the present invention. Figure 1 As shown, the vehicle braking force distribution device 100 at least includes but is not limited to: a turning state detection unit 102, a vehicle speed detection unit 104, a first yaw moment calculation unit 106, a second yaw moment calculation unit 108, a target moment calculation unit 110 and a braking force distribution control unit 112. In addition, the vehicle braking force distribution device 100 may also at least include but is not limited to: a steering device 130 and a brake device 140.

[0041] The turning state detection unit 102 detects whether the vehicle is in a turning state based on the driving state of the vehicle. The turning state can be determined, for example, based on the steering angle SA (or steering angle) of the steering wheel (steering device 130) in the vehicle. As an example, the turning state detection unit 102 can be implemented by a sensor installed on the steering device 130 and the control unit 120. This sensor is used to detect the operating angle of the steering device 130 relative to a reference position to determine whether the vehicle is in a turning state. The reference position can generally be the position where the steering wheel 130 of the vehicle (for example, the left and right wheels in front) keeps the vehicle moving straight. The operating angle of the steering device 130 detected by the sensor can be processed and analyzed by the control unit 120 to obtain whether the vehicle is in a turning state.

[0042] The vehicle speed detection unit 104 is used to detect whether the vehicle speed V is equal to or less than a specified threshold. The vehicle speed detection unit 104 can be implemented, for example, by a vehicle speed sensor and a control unit 120. The vehicle speed sensor is, for example, a sensor arranged near the wheel to detect the rotation speed to obtain the vehicle speed V. The vehicle speed V can also be detected by various available sensors, such as using a camera to perform image analysis and processing, radar, lidar, and other available technical means, which are not particularly limited by the present invention. When the vehicle speed sensor detects the vehicle speed V, the control unit 120 can compare the detected vehicle speed V with the specified threshold, and determine whether the vehicle speed V is equal to or less than the specified threshold.

[0043] The first yaw moment calculation unit 106 calculates the first yaw moment (or ideal yaw moment) M_ideal based on the driving state detected by the turning state detection unit 102, the vehicle speed V detected by the vehicle speed detection unit 104, and the first wheelbase L1 of the vehicle. Here, the first wheelbase L1 is the imaginary wheelbase (ideal wheelbase) of the vehicle. In this embodiment, when a vehicle with a long wheelbase (second wheelbase L2) turns at a low speed, the control unit 120 described later will control the braking force distribution of the vehicle's wheels so that the vehicle can turn with a shorter wheelbase (first wheelbase L1) to improve the turning performance of the vehicle. In other words, even a vehicle with a long wheelbase can make the vehicle behave like a short wheelbase vehicle when turning at a low speed.

[0044] The second yaw moment calculation unit 108 calculates the second yaw moment (or actual yaw moment) M_real based on the driving state detected by the turning state detection unit 102, the vehicle speed V detected by the vehicle speed detection unit 104, and the second wheelbase L2 based on the inherent value of the vehicle. Here, the second wheelbase L2 is a characteristic value of the vehicle itself, that is, an inherent value, which generally refers to the distance between the front and rear wheel centers of the vehicle, which is a fixed value.

[0045] The target moment calculation unit 110 calculates a target moment M_dem based on a difference between the first yaw moment M_ideal and the second yaw moment M_real.

[0046] The braking force distribution control unit 112 controls the braking force distribution amounts FR, FL, RR, and RL of the vehicle's wheels based on the target torque M_dem. For example, when the vehicle's driving state is in a turning state and the vehicle speed is equal to or less than a specified threshold, the braking force distribution control unit 112 controls the braking force distribution amounts FR, FL, RR, and RL of the wheels based on the target torque M_dem. Here, the condition in which the vehicle speed V is equal to or less than the specified threshold may be a condition in which the vehicle is in a stopped state or a low-speed state determined by the control unit 120 to be close to a stopped state and is below a first specified value, for example, a condition in which the intelligent parking assistance system is activated. The braking force distribution control performed by the braking force distribution control unit 112 is a vector control. In particular, when the vehicle is turning, the braking force and turning radius of each wheel of the left and right front wheels and the left and right rear wheels can be controlled.

[0047] With the vehicle braking force distribution device of this embodiment, when the vehicle turns at a low speed, the larger the steering angle is, the closer it is to the target behavior, that is, the vehicle turns in the behavior mode of a short wheelbase vehicle.

[0048] besides, Figure 1 The illustrated first yaw moment calculation unit 106, the second yaw moment calculation unit 108, the target moment calculation unit 110 and the braking force distribution control unit 112 can be implemented by the control unit 120. The turning state detection unit 102, the vehicle speed detection unit 104, the yaw rate detection unit (not shown) and other devices can be controlled by the control unit 120.

[0049] The control unit 120 is used to control the vehicle. The control unit 120 can control various behavior modes of the vehicle, such as acceleration, deceleration, parking, avoidance, etc., and can also detect the vehicle state or the state of the surrounding area of ​​the vehicle by controlling various sensors and detectors. For those skilled in the art, various control methods of the control unit 120 can be designed according to actual needs. The control unit 120 can be implemented by a processor, such as the ECU (Electronic Control Unit) unit of the vehicle. The ECU unit can be used to control various sensors and detectors of the vehicle. Thus, the control unit 120 can receive data, and perform various processing and judgments on the data, and then control various actuating components of the vehicle. Various system controls in the vehicle are controlled by the ECU unit. For example, starting the vehicle (such as the power switch (start switch)), checking each part after starting, controlling the vehicle display, etc.

[0050] Figure 2FIG. 1 is a circuit diagram of a vehicle braking force distribution device according to an embodiment of the present invention. Figure 2 As shown, the vehicle braking force distribution device 100 can receive the steering angle SA, the yaw rate and the vehicle speed V. As mentioned above, the steering angle SA can be detected by the turning state detection unit 102, for example, by a steering angle sensor provided in the steering device 130. The yaw rate can be regarded as an angular velocity in the yaw axis direction, which can be detected by a yaw sensor not shown. The vehicle speed V can be detected by the vehicle speed detection unit 104.

[0051] In addition, the steering angle detected by the turning state detection unit 102 can be used by the control unit 120 to determine whether the vehicle is turning and the turning direction. As an example, the vehicle braking force distribution device 100 can also include: a first wheelbase setting unit 114 can set the first wheelbase (ideal wheelbase) L1 based on the operating angle SA. The first wheelbase setting unit 114 can use a steering angle map to search. Figure 2 As shown, when the vehicle turns and the vehicle speed is below a specified threshold, the first wheelbase setting unit (steering angle diagram) 114 is set in such a manner that the first wheelbase L1 is less than or equal to the second wheelbase L2, and in a specified interval, the first wheelbase L1 is set in such a manner that the larger the current steering angle SA is, the smaller the value of the first wheelbase L1 is.

[0052] In this way, the embodiment can set the ideal wheelbase (first wheelbase) L1 based on the vehicle's steering angle SA. In this way, when the deviation from the actual yaw moment increases, the target yaw moment also increases, and thus the target yaw moment also increases, so the effect of a long-axle vehicle turning with a small radius can be achieved.

[0053] The first yaw moment calculation unit 106 calculates and outputs the first yaw moment (ideal yaw moment) M_ideal based on the driving state (which may include steering angle, yaw rate, etc.) detected by the turning state detection unit 102, the vehicle speed V detected by the vehicle speed detection unit 104, and the first wheelbase (imaginary wheelbase, ideal wheelbase) L1 of the vehicle.

[0054] Furthermore, the second yaw moment calculation unit 108 calculates and outputs a second yaw moment (actual yaw moment) M_real based on the driving state (which may include the steering angle, yaw rate, etc.) detected by the turning state detection unit 102, the vehicle speed V detected by the vehicle speed detection unit 104, and the second wheelbase L2 based on the inherent value of the vehicle. Here, the second wheelbase L2 is a characteristic value of the vehicle itself, that is, an inherent value, and can be input from a memory that cooperates with the control unit 120, for example.

[0055] The target moment calculation unit 110 receives the first yaw moment (ideal yaw moment) M_ideal from the first yaw moment calculation unit 106 and the second yaw moment (actual yaw moment) M_real from the second yaw moment calculation unit 108 to calculate and output the target moment M_dem. The target moment M_dem is calculated by the following equation (1).

[0056] M_dem = M_ideal – M_real (1)

[0057] The first yaw moment M_ideal and the second yaw moment M_real can be calculated according to the following formula (2).

[0058]

[0059] Wherein, T is the torque, ρ is the turning radius, M is the yaw torque, δ is the steering angle, V is the vehicle speed, r is the yaw rate, Kf is the front wheel cornering force, Kr is the rear wheel cornering force, and L is the wheelbase.

[0060] In addition, the braking force distribution control unit 112 controls the braking force distribution amounts FR, FL, RR, and RL of the wheels of the vehicle (for example, the front, rear, left, and right wheels of a four-wheeled vehicle) based on the target torque M_dem. As an example, the braking force distribution control unit 112 may include: a braking force generating wheel selection unit 112a and a limiter 112b.

[0061] The braking force generating wheel selection unit 112a can determine which wheels to select as the control objects of the individual braking force based on the state of the vehicle detected by the turning state detection unit 102, such as the turning direction. The limiter 112b can limit the upper limit value of the braking force of each wheel. As a result, the braking force distribution control unit 112 can control the braking force distribution amount FR, FL, RR, RL of each wheel of the vehicle based on the target torque M_dem. In this way, the control unit 120 can control the actuators (not shown) of each wheel of the braking device 140 to control the braking force of each wheel based on the braking force distribution amount FR, FL, RR, RL of each wheel.

[0062] Therefore, because the braking force distribution control of this embodiment considers the wheelbase (second wheelbase) L2 of the vehicle itself and the ideal wheelbase (first wheelbase) L1 to generate the target torque M_dem, when a long wheelbase vehicle turns at a low speed, the vehicle can be controlled in the behavior mode of a short wheelbase vehicle. Therefore, when turning at a low speed, such as when turning or picking up a car in a narrow parking lot, the turning characteristics can be improved.

[0063] Figure 31 is a schematic diagram of a scenario of vehicle braking force distribution according to an embodiment of the present invention. As described above, the first wheelbase setting unit 114 sets the first wheelbase L1 in such a way that the larger the current steering angle SA is, the smaller the value of the first wheelbase L1 is. Figure 3 As shown, when a long wheelbase vehicle turns at a low speed, its turning radius is larger. At this time, the vehicle can be set to control the braking force of each wheel in the behavior mode of a short wheelbase vehicle. When the steering device 130 is not operated, the steering angle SA is 0, and the wheelbase is the largest. When the operation amount of the steering device 130 gradually increases, the steering angle SA gradually increases, and the wheelbase gradually decreases. When the operation amount of the steering device 130 continues to increase, the steering angle SA also continues to increase, and the wheelbase further decreases.

[0064] According to the embodiment of the present invention, when operating the steering device 130, the target yaw moment M_dem is also applied to make the turning radius smaller. In this way, the vehicle can turn along the trajectory C (the driving route of the dashed line vehicle), so even if it is a long wheelbase vehicle, it can be controlled in the behavior mode of a short wheelbase vehicle.

[0065] By continuously reducing the first wheelbase L1 in accordance with the current steering angle, even a long wheelbase vehicle can be smoothly transformed into a short wheelbase vehicle. This reduces discomfort caused by changes in vehicle behavior. If the target torque M_dem is set to a constant, the vehicle will shake. In addition, according to this embodiment, the turning performance of the vehicle at low speed can also be improved.

[0066] Figure 4 1 is an explanatory diagram for explaining the hysteresis characteristic of the first wheelbase according to an embodiment of the present invention. According to an embodiment of the present invention, the first wheelbase L1 is set to have a hysteresis characteristic. Figure 4 As shown, when the steering angle SA gradually increases,

[0067] The length of the first wheelbase near the reference position of the steering device 130 is the same as the length of the second wheelbase, but a dead zone (a section where the length of the first wheelbase does not change) is set near the reference position, and when the steering angle SA exceeds the dead zone angle, the first wheelbase L1 gradually decreases. When the steering angle SA reaches the first threshold a1, the first wheelbase is set to the minimum value min. Thereafter, even if the steering angle SA increases, the length of the first wheelbase L1 does not change. Thereafter, in the case where the steering angle SA decreases, even if the steering angle SA reaches the first threshold a1, the length of the first wheelbase L1 does not change. In the case where the steering angle SA becomes less than the second threshold a2 which is smaller than the first threshold a1, the first wheelbase L1 starts to increase from the minimum value min and gradually increases as the steering angle SA decreases. When the position of the steering device 130 reaches the vicinity of the reference position, the first wheelbase L1 becomes equal to the length of the second wheelbase L2. In other words, as the time point when the length of the first wheelbase L1 starts to change, the second threshold a2 is not considered when the steering angle SA increases, and the first threshold a1 is not considered when the steering angle SA decreases. Therefore, when the steering angle SA decreases, the first wheelbase L1 is less likely to increase than when the steering angle SA increases.

[0068] By setting the first wheelbase (ideal wheelbase) L1 to have a hysteresis characteristic, since the first wheelbase L1 becomes difficult to return when the steering device 130 is turned back, hunting, that is, the behavior of fluctuating up and down unstably near the indicated target value, can be prevented compared with conventional technologies that do not have hysteresis.

[0069] In addition, according to an embodiment of the present invention, the vehicle braking force distribution device 100 may further include: an obstacle detection unit 116 and a contact judgment unit 118. The obstacle detection unit 116 is used to detect obstacles around the vehicle, such as other vehicles, personnel, guard pipes, guard poles, etc. The obstacle detection unit 116 may be, for example, a camera arranged around the vehicle, which captures images around the vehicle, and the control unit 120 or an independent image processing unit determines whether there are obstacles around the vehicle through image analysis, etc. The obstacle detection unit 116 may also use a laser device to detect whether there are obstacles near the vehicle. The obstacle detection unit 116 may also use any other sensor or detection equipment arranged on the vehicle to detect obstacles.

[0070] The contact determination unit 118 is used to determine the possibility of the obstacle contacting (colliding) with the inner side of the turning direction of the host vehicle based on the above-mentioned obstacle. The contact determination unit 118 can be implemented by the control unit 120, for example. The contact determination unit 118 can determine the possibility of the obstacle contacting with the inner side of the turning direction of the host vehicle based on the distance between the vehicle and the obstacle detected by the obstacle detection unit 116.

[0071] At this time, the first wheelbase setting unit 114 may set the first wheelbase L1 according to the determination result of the contact determination unit 118. When the vehicle is turning and the vehicle speed V is equal to or less than a predetermined threshold, and it is determined that the obstacle may contact the vehicle, the first wheelbase setting unit 114 sets the first wheelbase L1 to a value larger than the current value.

[0072] In contrast to the above-described implementation, the above-described description is that when the vehicle turns at a low speed, the vehicle is controlled to turn in the manner of a short-wheelbase vehicle using a smaller turning radius. However, if during this control process, an obstacle appears near the vehicle and the obstacle may come into contact with the vehicle, if this control method is continued, the probability of the vehicle coming into contact with the obstacle may increase.

[0073] like Figure 5 As shown, when the obstacle detection unit 116 detects that there is an obstacle near the vehicle, and the contact determination unit 118 determines that the obstacle will contact the vehicle, the steering angle diagram in the first wheelbase setting unit 114 is changed from the left control mode to the right control mode. Figure 5 In the steering angle diagram on the left, in a predetermined range, as the steering angle SA increases, the wheelbase (first wheelbase) L1 gradually decreases. Figure 5 In the steering angle diagram on the right, as the steering angle SA increases, the wheelbase (first wheelbase) L1 gradually increases.

[0074] In other words, when there is an obstacle near the vehicle that may come into contact with the vehicle, the first wheelbase setting unit 114 changes the way the first wheelbase L1 and the steering angle change. Figure 5 In the control method on the right side, once the contact determination unit 118 determines that the obstacle will contact the vehicle, the control unit 120 changes the steering angle map through the first wheelbase setting unit 114 to distribute the braking force of the vehicle wheels. As a result, the vehicle can turn with a larger turning radius to avoid contact with the obstacle.

[0075] Furthermore, in another situation, the first wheelbase setting unit 114 may set the first wheelbase L1 based on the determination result of the contact determination unit 118 and the steering angle SA. When the vehicle is turning and the vehicle speed is equal to or less than the predetermined threshold value, when the contact determination unit 118 determines that there is a possibility of contact between the obstacle and the vehicle, the first wheelbase setting unit 114 sets the first wheelbase L1 in a manner that is greater than or equal to the second wheelbase L2, and sets the first wheelbase L1 in a manner that the greater the current steering angle SA is, the greater the value of the first wheelbase L1 is within the prescribed interval. Thus, the first wheelbase increases gradually or in stages in coordination with the steering angle SA. In this example, when the vehicle is at risk of contact with an obstacle, the braking distribution control of the vehicle is performed by increasing the first wheelbase L1, thereby avoiding contact (collision) with the obstacle.

[0076] Figure 6 (a) to Figure 6 (c) is a schematic diagram of a situation of vehicle braking force distribution according to another embodiment of the present invention. Figure 6 (a), when the steering device 130 is not operated at the beginning, the steering angle SA is 0, and the wheelbase is at its maximum. Then, the steering device 130 is gradually operated, and the first wheelbase setting unit 114 sets the first wheelbase L1 in such a way that the larger the current steering angle SA is, the smaller the value of the first wheelbase L1 is (using Figure 5 The steering angle diagram on the left). When a long wheelbase vehicle turns at a low speed, its turning radius is large. At this time, the vehicle can be set to control the braking force of each wheel in the behavior mode of a short wheelbase vehicle. When the operation amount of the steering device 130 gradually increases, the steering angle SA gradually increases, and the first wheelbase L1 gradually decreases. When the operation amount of the steering device 130 continues to increase, the steering angle SA also continues to increase, and the wheelbase further decreases.

[0077] Afterwards, if Figure 6 As shown in (b), at this time, if the obstacle detection unit 116 detects that there is an obstacle near the vehicle, and the contact judgment unit 118 determines that the obstacle will contact the vehicle, the first wheelbase setting unit 114 is replaced by Figure 5 The first wheelbase L1 is set by using the steering angle diagram on the right. Figure 6 (b) Figure 6 As shown in (c), the first wheelbase setting unit 114 sets the first wheelbase L1 so that the first wheelbase L1 increases as the steering angle SA increases. In other words, when an obstacle that may come into contact with the vehicle is detected, the vehicle is turned with a larger turning radius.

[0078] Similarly, in this embodiment, when avoiding an obstacle, the target yaw moment M_dem is applied simultaneously with the steering device 130 to increase the turning radius, so that the vehicle can turn along the trajectory C1 (the driving route of the dashed line vehicle) to avoid contact with the obstacle.

[0079] In this example, when the vehicle is at risk of contacting an obstacle, the vehicle's braking distribution control is performed by increasing the first wheelbase L, thereby avoiding contact (collision) with the obstacle. At this time, the first wheelbase L1 can be set to be longer than the second wheelbase L2 of the vehicle's inherent value.

[0080] According to a variation of the embodiment of the present invention, when the vehicle is moving backward, braking force can be applied only to the inner side of the turn of the rear wheels of the vehicle, thereby improving the turning characteristics of the vehicle compared to when the vehicle is moving forward and backward and braking is applied.

[0081] Furthermore, in the present embodiment, when the vehicle is traveling on a slope or a low-friction road surface, the first wheelbase L1 may be changed to improve the turning characteristics of the vehicle.

[0082] Furthermore, in the above-mentioned embodiment, the virtual wheelbase is changed by the steering angle, but the virtual wheelbase preferred by the driver may be changed by a human-machine interface (HMI) switch or the like.

[0083] In addition, the above embodiment records the method of using braking force as a method of changing the imaginary wheelbase, but it can also be implemented by any one of the methods of using braking force and the method of using left and right braking / driving force control driven by a motor. Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it; although the present invention is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein by equivalent; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present invention.

Claims

1. A vehicle braking force distribution device, characterized in that: include: A turning state detection unit, used for detecting whether the vehicle is in a turning state based on the driving state of the vehicle; A vehicle speed detection unit, used to detect whether the vehicle speed is equal to or less than a specified threshold; A first yaw moment calculation unit, which calculates a first yaw moment based on the driving state, the vehicle speed, and a first wheelbase of the vehicle, wherein the first wheelbase is a virtual wheelbase of the vehicle; a second yaw moment calculation unit that calculates a second yaw moment based on the running state, the vehicle speed, and a second wheelbase based on an inherent value of the vehicle; a target moment calculation unit, configured to calculate a target moment based on a difference between the first yaw moment and the second yaw moment; as well as a braking force distribution control unit, configured to control the braking force distribution amount of the wheels of the vehicle based on the target torque; The braking force distribution control unit controls the braking force distribution amount of the wheels based on the target torque when the vehicle is turning and the vehicle speed is equal to or less than a prescribed threshold.

2. The vehicle braking force distribution device according to claim 1, characterized in that: The driving state includes: steering angle, The vehicle braking force distribution device further includes: a first wheelbase setting unit, which sets the first wheelbase based on the steering angle, When the vehicle is turning and the vehicle speed is below the specified threshold, the first wheelbase setting unit is set in a manner such that the first wheelbase is less than or equal to the second wheelbase, and in a specified interval, the first wheelbase is set in a manner such that the value of the first wheelbase decreases as the current steering angle increases.

3. The vehicle braking force distribution device according to claim 2, characterized in that: The first wheelbase has a hysteresis characteristic. When the steering angle increases, when the steering angle reaches a first threshold, the first wheelbase is set to a minimum value. Thereafter, when the steering angle decreases and becomes smaller than a second threshold that is smaller than the first threshold, the first wheelbase increases from the minimum value, and is less likely to increase when the steering angle decreases than when the steering angle increases.

4. The vehicle braking force distribution device according to claim 1, characterized in that: Also includes: An obstacle detection unit, used to detect obstacles around the vehicle; a contact determination unit, configured to determine, based on the obstacle, the possibility that the obstacle contacts the inner side of the turning direction of the vehicle; as well as a first wheelbase setting unit, configured to set the first wheelbase according to a determination result of the contact determination unit; When the vehicle is turning and the vehicle speed is equal to or less than the predetermined threshold, and when it is determined that the obstacle may come into contact with the vehicle, the first wheelbase setting unit sets the first wheelbase to a value greater than a current value.

5. The vehicle braking force distribution device according to claim 4, characterized in that: Also includes: The driving state includes: steering angle, The first wheelbase setting unit sets the first wheelbase based on the determination result of the contact determination unit and the steering angle. When the vehicle is turning and the vehicle speed is equal to or less than a predetermined threshold, When the contact determination unit determines that there is a possibility that the obstacle is in contact with the vehicle, The first wheelbase setting unit sets the first wheelbase so that the first wheelbase is greater than or equal to the second wheelbase, and sets the first wheelbase so that the value of the first wheelbase increases as the current steering angle increases in a predetermined section.

6. A vehicle braking force distribution method, characterized in that: include: Based on the driving state of the vehicle, detecting whether the vehicle is in a turning state; Detecting whether the speed of the vehicle is equal to or less than a specified threshold; Calculating a first yaw moment based on the driving state, the vehicle speed, and a first wheelbase of the vehicle, wherein the first wheelbase is an imaginary wheelbase of the vehicle; calculating a second yaw moment based on the driving state, the vehicle speed, and a second wheelbase based on an intrinsic value of the vehicle; calculating a target moment based on a difference between the first yaw moment and the second yaw moment; as well as When the vehicle is turning and the vehicle speed is equal to or less than a prescribed threshold, a braking force distribution amount of wheels of the vehicle is controlled based on the target torque.

7. The vehicle braking force distribution method according to claim 6, characterized in that: The driving state includes: steering angle, The vehicle braking force distribution method: the first wheelbase is set based on the steering angle, and when the vehicle turns and the vehicle speed is below the specified threshold, the first wheelbase is set in a manner that the first wheelbase is less than or equal to the second wheelbase, and in a specified range, the greater the current steering angle, the smaller the value of the first wheelbase.

8. The vehicle braking force distribution method according to claim 7, characterized in that: The first wheelbase has a hysteresis characteristic. When the steering angle increases, when the steering angle reaches a first threshold, the first wheelbase is set to a minimum value. Thereafter, when the steering angle decreases and becomes smaller than a second threshold that is smaller than the first threshold, the first wheelbase increases from the minimum value, and is less likely to increase when the steering angle decreases than when the steering angle increases.

9. The vehicle braking force distribution method according to claim 6, characterized in that: Also includes: Detecting obstacles around the vehicle; determining the possibility that the obstacle contacts the inner side of the turning direction of the vehicle to obtain a determination result; According to the judgment result, setting the first wheelbase; as well as When the vehicle is turning and the vehicle speed is equal to or less than the prescribed threshold, and when it is determined that the obstacle may come into contact with the vehicle, the first wheelbase is set to a value greater than a current value.

10. The vehicle braking force distribution method according to claim 9, characterized in that: The driving state includes: steering angle, The vehicle braking force distribution method further includes: setting the first wheelbase based on the determination result and the steering angle; and When the vehicle is turning and the vehicle speed is equal to or less than the threshold value, when the contact judgment unit judges that there is a possibility of contact between the obstacle and the vehicle, the first wheelbase is set in such a manner that the first wheelbase is greater than or equal to the second wheelbase, and in such a manner that the value of the first wheelbase increases as the current steering angle increases within a specified interval.

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