Vehicle posture control method and vehicle posture control program

Abstract

To provide a vehicle posture control method and a program for stabilizing the posture of a vehicle when abnormal air pressure occurs in one wheel.SOLUTION: A vehicle posture control method of the present disclosure includes: a plurality of wheels disposed at left and right positions on the front and rear of a vehicle body; drive units that respectively drive the plurality of wheels to rotate the wheels; and a suspension device that connects the plurality of wheels to the vehicle body such that a predetermined anti-squat angle is formed between the vehicle body and each of the wheels. The vehicle posture control method includes the steps of: detecting abnormal air pressure of the plurality of wheels; and when abnormal air pressure is detected in a first wheel of the plurality of wheels, distributing drive power for rotatably driving the other wheels to the drive units in order to lift upward a part of the vehicle body in which the first wheel is disposed, relative to the other wheels of the plurality of wheels than the first wheel with the use of the anti-squat force applied by the suspension device.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a vehicle attitude control method and a vehicle attitude control program. [Background technology]

[0002] If a wheel puncture occurs while a vehicle is moving, it becomes difficult to maintain a normal running trajectory, and the possibility of an accident increases. For this reason, technology is being developed to allow a vehicle to continue traveling safely even if a wheel puncture occurs while the vehicle is moving.

[0003] For example, the following Patent Document 1 describes a method of determining the yaw moment to be added and controlling each wheel in order to quickly compensate for the yaw moment caused by a punctured wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2021 / 0206383 Summary of the Invention [Problem to be solved by the invention]

[0005] When the air pressure of one of the wheels drops significantly due to a puncture or the like, the diameter of the contact surface of that wheel becomes smaller than that of the other wheels. This not only generates the above-mentioned yaw moment in the vehicle, but also causes the vehicle body to partially sink as the punctured wheel collapses, causing the vehicle to tilt mainly in the roll direction. Such tilt in the roll direction can cause passengers to fall over or cargo to shift. In particular, in self-driving vehicles, which have been put into practical use in recent years, passengers are not necessarily always facing forward, so there is a high possibility that the above-mentioned passengers will fall over.

[0006] Although the above-mentioned Patent Document 1 describes compensating (or canceling) the yaw moment caused by a puncture, it does not particularly consider the tilt of the vehicle caused by the puncture. Therefore, there is room for improvement in the attitude control when a vehicle has a puncture.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a vehicle attitude control method and program for stabilizing the vehicle attitude when an air pressure abnormality occurs in one of the wheels. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, a vehicle attitude control method according to a first aspect of the present disclosure is a method for controlling the attitude of a vehicle (1) including a plurality of wheels (11, 12, 13, 14) arranged at the left and right positions at the front and rear of a vehicle body (2), drive devices (21, 22, 23, 24) that rotate and drive each of the plurality of wheels, and suspension devices (41, 42, 43, 44) that connect the vehicle body and the plurality of wheels so that predetermined anti-squat angles (θf, θr) are formed, the method including: a step (S12) of detecting an abnormality in air pressure of the plurality of wheels; and a step (S15) of distributing a drive force to the drive device that rotates and drives the other wheels when an abnormality in air pressure is detected in a first wheel of the plurality of wheels, in order to raise a portion of the vehicle body where the first wheel is arranged relative to other wheels of the plurality of wheels other than the first wheel by utilizing an anti-squat force acting by the suspension device.

[0009] In the above-mentioned vehicle attitude control method, when an air pressure abnormality occurs in one wheel, the tilt of the vehicle body is reduced or eliminated by utilizing the anti-squat force, so that the tilt of the vehicle body can be reduced or eliminated simply by distributing the driving force of the other wheels. Furthermore, since the tilt of the vehicle body is reduced or eliminated, it is possible to prevent passengers from falling over or cargo from shifting inside the vehicle.

[0010] A vehicle attitude control method according to a second aspect of the present disclosure is the vehicle attitude control method according to the first aspect, wherein the step of distributing driving force to the drive unit includes a step (S13) of detecting an amount of deformation of the first wheel and estimating an amount of inclination of the vehicle body when an air pressure abnormality is detected in the first wheel, and a step (S14) of adjusting an amount of distribution of driving force to the drive unit that rotates the other wheels based on the estimated amount of inclination.

[0011] A vehicle attitude control method according to a third aspect of the present disclosure is the vehicle attitude control method according to the first aspect, wherein the step of distributing driving force to the drive device includes a step (S23) of detecting a yaw moment generated in the vehicle body due to an abnormality in air pressure of the first wheel, a step (S24) of calculating a yaw rate required to compensate for the detected yaw moment, and a step (S25) of distributing driving force to the drive device that rotates the other wheels in order to raise a portion of the vehicle body located on the first wheel side relative to the other wheels and to obtain the required yaw rate.

[0012] A vehicle attitude control method according to a fourth aspect of the present disclosure is the vehicle attitude control method according to the third aspect, further comprising a step (S35) of operating at least one of a braking device (4) and a steering device (5) in order to raise a portion of the vehicle body located on the first wheel side relative to the other wheels and to obtain the required yaw rate.

[0013] A vehicle attitude control method according to a fifth aspect of the present disclosure is the vehicle attitude control method according to the fourth aspect, wherein the braking device brakes the other wheels, and the steering device steers the other wheels.

[0014] A vehicle attitude control program according to a sixth aspect of the present disclosure causes at least one processor (51) of a computer provided in a vehicle including a plurality of wheels respectively arranged at the left and right positions at the front and rear of the vehicle body, a drive device that rotates and drives each of the plurality of wheels, and a suspension device that connects the vehicle body and the plurality of wheels so that a predetermined anti-squat angle is formed, to execute a process of detecting an abnormality in air pressure in the plurality of wheels, and, when an abnormality in air pressure is detected in a first wheel of the plurality of wheels, a process of distributing a driving force to the drive device that rotates and drives the other wheels in order to raise a portion of the vehicle body located on the side of the first wheel relative to the other wheels of the plurality of wheels excluding the first wheel by utilizing the anti-squat force acting by the suspension device. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an example of a vehicle on which a vehicle attitude control method according to a first embodiment of the present disclosure can be implemented; [Diagram 2] 2 is a schematic diagram illustrating an example of a hardware configuration of a control system for the vehicle shown in FIG. 1. [Diagram 3] 2 is an explanatory diagram showing the vehicle shown in FIG. 1 in a normal traveling state as viewed from a plurality of viewpoints. FIG. [Figure 4] 4 is a flowchart showing an example of a vehicle attitude control method according to the first embodiment of the present disclosure. [Diagram 5] 5 is a graph showing an example of changes in various parts of a vehicle when the vehicle attitude control method shown in FIG. 4 is executed. [Figure 6] 4 is an explanatory diagram showing a state in which the left front wheel of the vehicle shown in FIG. 3 has a flat tire, as viewed from multiple viewpoints. FIG. [Figure 7] 7 is an explanatory diagram showing a state after the vehicle attitude control method shown in FIG. 4 is performed on the vehicle shown in FIG. 6, as viewed from a plurality of viewpoints. [Figure 8] 10 is a flowchart showing an example of a vehicle attitude control method according to a second embodiment of the present disclosure. [Figure 9]9 is a graph showing an example of changes in various parts of a vehicle when the vehicle attitude control method shown in FIG. 8 is executed. [Figure 10] 9 is an explanatory diagram showing a state after the vehicle attitude control method shown in FIG. 8 is performed on the vehicle shown in FIG. 6, as viewed from a plurality of viewpoints. [Figure 11] 1. FIG. 4 is a schematic diagram illustrating another example of the hardware configuration of the control system of the vehicle shown in FIG. [Figure 12] 13 is a flowchart showing an example of a vehicle attitude control method according to a third embodiment of the present disclosure. [Figure 13] 13 is a graph showing an example of changes in various parts of a vehicle when the vehicle attitude control method shown in FIG. 12 is executed. [Figure 14] 13 is an explanatory diagram showing a state after the vehicle attitude control method shown in FIG. 12 is performed on the vehicle shown in FIG. 6, as viewed from a plurality of viewpoints. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment for carrying out the present disclosure will be described with reference to the drawings. Note that, in the following, the scope necessary for the explanation to achieve the object of the present disclosure is shown in a schematic manner, and the scope necessary for the explanation of the relevant part of the present disclosure will be mainly explained, and the parts that are omitted from the explanation will be referred to as publicly known techniques.

[0017] <First embodiment> The vehicle attitude control method according to the first embodiment of the present disclosure may be adopted in a vehicle 1 such as an automobile as shown in FIG. 1 to control the attitude of the vehicle when an abnormality in the air pressure of one of the wheels occurs, more specifically, when a flat tire occurs.

[0018] As shown in FIG. 1, the vehicle 1 includes a vehicle body 2, a plurality of wheels 11, 12, 13, and 14 (four in this embodiment) disposed at the left and right positions in front and rear of the vehicle body 2, respectively, and motors 21, 22, 23, and 24 as an example of a drive device for rotating and driving each of the plurality of wheels 11, 12, 13, and 14. Of these, the vehicle body 2 may include a vehicle cabin including a seat on which a driver or other passenger can sit. In FIG. 1, only the outer edge of the vehicle body 2 is illustrated so that the structure of the suspension of the vehicle 1 can be easily understood. Such illustration is also applicable to the figures shown at the top of FIG. 3, FIG. 6, FIG. 7, FIG. 10, and FIG. 14, which will be described later. In FIG. 1, the traveling direction of the vehicle 1 is indicated by an arrow D1, and the direction indicated by the arrow D1 may be referred to as the forward direction, the direction opposite to the direction indicated by the arrow D1 may be referred to as the backward direction, and the direction intersecting with the arrow D1 may be referred to as the left-right direction.

[0019] The wheels 11, 12, 13, and 14 may include two wheels, a left front wheel 11, a right front wheel 12, a left rear wheel 13, and a right rear wheel 14, arranged at the four corners of the bottom of the vehicle body 2. These wheels 11, 12, 13, and 14 may include tires that are mounted on general automobiles, such as normal tires, as well as tires that deform relatively little when punctured, such as run-flat tires.

[0020] The motors 21, 22, 23, and 24 may be, for example, in-wheel motors disposed inside the wheels 11, 12, 13, and 14 and driving and rotating each of the wheels 11, 12, 13, and 14. Therefore, the motors 21, 22, 23, and 24 may be capable of rotating each of the wheels 11, 12, 13, and 14 that they drive and rotate independently of the other wheels.

[0021] Furthermore, the vehicle 1 may include at least one ECU (Electronic Control Unit) 3 as an example of an electronic control device for controlling various components mainly including the motors 21, 22, 23, and 24.

[0022] The ECU 3 may be capable of distributing driving force to at least the motors 21, 22, 23, and 24. The driving forces of the motors 21, 22, 23, and 24 may be controlled by adjusting, for example, the torque or the driving current. The ECU 3 may be configured, for example, by a known computer. As shown in FIG. 2, the ECU 3 configured by a known computer may include at least one processor 51, a ROM (Read Only Memory) 52 and a RAM (Random Access Memory) 53 as examples of memory, a storage 54, and an input / output interface 55. These components may be connected to each other via an internal bus 56 so as to be able to communicate with each other.

[0023] At least one processor 51 may be configured, for example, as a CPU (Central Processing Unit) and may be capable of executing various programs and controlling each part. Specifically, this processor 51 may be capable of reading out various programs stored in the ROM 52 or storage 54 and executing the programs using the RAM 53 as a working area. The processor 51 may be capable of controlling the motors 21, 22, 23, and 24 and performing various arithmetic processing according to the above-mentioned programs.

[0024] The ROM 52 may be capable of storing various programs and various data, and the RAM 53 may be capable of temporarily storing programs or data as a working area.

[0025] The storage 54 can be configured with a recording medium such as a hard disk drive (HDD), a solid state drive (SSD), a flash memory, etc. The storage 54 may at least temporarily store various programs including an operating system, various data necessary to operate the motors 21, 22, 23, and 24, and the like.

[0026] The input / output interface 55 may be connected to various components of the vehicle 1 to transmit and receive data. The input / output interface 55 in this embodiment may be connected to the motors 21, 22, 23, and 24, and the air pressure sensors 31, 32, 33, and 34 described below. The input / output interface 55 may be connected to components other than those described above, and may include, for example, a display means in an instrument panel that notifies an abnormality in the air pressure of the wheels 11, 12, 13, and 14, a connector to which an external recording medium can be connected, and various drives such as a DVD drive.

[0027] The vehicle 1 may also have an air pressure abnormality detection means for detecting an air pressure abnormality, such as a puncture, in the wheels 11, 12, 13, and 14. Specifically, the vehicle 1 may have a tire pressure monitoring system (TPMS). The TPMS may include air pressure sensors 31, 32, 33, and 34 that are provided in each of the wheels 11, 12, 13, and 14 and can detect an air pressure abnormality. The air pressure sensors 31, 32, 33, and 34 may be integrated with an air valve or fixed inside the wheel. When the air pressure of each of the wheels 11, 12, 13, and 14 falls below a preset threshold value TH (see FIG. 5, etc.), the air pressure sensors 31, 32, 33, and 34 can notify the ECU 3 of the occurrence of an air pressure abnormality in the wheel via wired or wireless communication.

[0028] In this embodiment, an example is shown in which air pressure abnormalities in the wheels 11, 12, 13, 14 are detected by air pressure sensors 31, 32, 33, 34. However, various sensors capable of detecting air pressure abnormalities can be used as the air pressure detection means possessed by the vehicle 1. Specifically, for example, a sensor capable of detecting the rotation speed of the wheels can be used instead of the air pressure sensors 31, 32, 33, 34. Note that if a sensor that detects the rotation speed of the wheels is used, the air pressure of the wheels can be determined by calculation from the rotation speed of the wheels detected by the sensor.

[0029] As shown in Fig. 3, the vehicle 1 described above includes suspension devices 41, 42, 43, and 44 that connect the vehicle body 2 and a plurality of wheels 11, 12, 13, and 14. Fig. 3 shows, from above, a view of the vehicle 1 as seen from the left side, and a view as seen from the front, in that order. The same is true for Figs. 6, 7, 10, and 14, which will be described later.

[0030] The suspensions 41, 42, 43, 44 are connected between the vehicle body 2 and each wheel 11, 12, 13, 14 so that predetermined anti-squat angles θf, θr are formed between the vehicle body 2 and each wheel 11, 12, 13, 14. The suspensions 41, 42, 43, 44 may include, for example, shock absorbers. The wheels 11, 12, 13, 14 connected to the vehicle body 2 via the suspensions 41, 42, 43, 44 having predetermined anti-squat angles θf, θr can rotate around the base ends of the suspensions 41, 42, 43, 44 when the vehicle 1 accelerates or decelerates. The distance between the wheels 11, 12, 13, 14 and the vehicle body 2 can be changed by the rotation. The anti-squat angles θf (sometimes called "anti-dive angles") of the suspensions 41, 42 connected to the left front wheel 11 and the right front wheel 12 may be set to be substantially the same angle. Similarly, the anti-squat angles θr of the suspension devices 43, 44 connected to the left rear wheel 13 and the right rear wheel 14 may be set to be substantially the same angle.

[0031] Regarding the vehicle 1 including the above-mentioned suspension devices 41, 42, 43, 44, the following briefly describes the vertical forces acting between the vehicle body 2 and the wheels 11, 12, 13, 14 due to the driving forces from the motors 21, 22, 23, 24. 11 , F 12 , F 13 , F 14 When each of the wheels 11, 12, 13, 14 rotates due to the suspension devices 41, 42, 43, 44, a vertical force is generated between each of the wheels 11, 12, 13, 14 and the vehicle body 2. The vertical force generated between the wheels 11, 12, 13, 14 and the vehicle body 2, i.e., an anti-squat force FX 11 , FX 12, FX 13 , FX 14 can be expressed by the following formula (1). In the following formula (1), the driving force F 11 , F 12 , F 13 , F 14 is positive when acting in the forward direction of the vehicle 1 and negative when acting in the backward direction, and the anti-squat force FX 11 , FX 12 , FX 13 , FX 14 is positive when the wheels 11, 12, 13, 14 move in a direction toward the vehicle body 2, i.e., upward, and is negative when the wheels move in a downward direction. 11 , FX 12 is sometimes called the "anti-dive force."

number

[0032] As can be seen from the above formula (1), a driving force acts on the left front wheel 11 and the right front wheel 12 in a direction in which the vehicle 1 moves forward (i.e., driving force F 11 , F 12 is positive) and anti-squat force FX 11 , FX 12 is negative. Therefore, the anti-squat force FX 11 , FX 12 On the other hand, a driving force acts on the left rear wheel 13 and the right rear wheel 14 in a direction in which the vehicle 1 moves forward (i.e., driving force F 13 , F 14 is negative) and the anti-squat force FX 13 , FX 14 is positive. Therefore, the anti-squat force FX 13 , FX 14 The driving forces F of the motors 21, 22, 23, and 24 act in a direction moving the vehicle body 2 away from the left front wheel 11 and the right front wheel 12, that is, in a direction lifting the vehicle body 2 upward. 11 , F 12 , F 13 , F14 By adjusting the magnitude of the anti-squat force FX acting between each wheel 11, 12, 13, 14 and the vehicle body 2, 11 , FX 12 , FX 13 , FX 14 In the vehicle attitude control method according to the present embodiment, the magnitude of the anti-squat force FX 11 , FX 12 , FX 13 , FX 14 By utilizing this, it is possible to adjust the inclination in the roll direction of the vehicle body 2 that occurs when a flat tire occurs.

[0033] The vehicle attitude control method according to this embodiment can be realized in the vehicle 1 having the above-mentioned configuration. The vehicle attitude control method according to this embodiment will be described below mainly with reference to Figs. 4 to 7. The vehicle attitude control method described below may be implemented by executing a control program that causes at least one processor 51 of a computer constituting the ECU 3 to execute a predetermined operation. This control program may be stored in a recording means such as the storage 54 as a vehicle attitude control program, or may be provided in the form of a computer-readable recording medium.

[0034] The following description will exemplify a posture control method when an air pressure abnormality occurs in the left front wheel 11 of the vehicle 1 shown in Fig. 1. Furthermore, Fig. 5 shows, from top to bottom, a graph showing the progress of the air pressure of the first wheel (left front wheel 11) in which an air pressure abnormality has been detected, a graph showing the change in the roll direction occurring in the vehicle 1, and a graph showing the progress of the driving force to each of the motors 21, 22, 23, and 24.

[0035] The vehicle attitude control method according to this embodiment includes at least a step (S12) of detecting an air pressure abnormality in the plurality of wheels 11, 12, 13, 14, and a step (S15) of distributing driving force to motors 22, 23, 24 which rotate and drive the other wheels 12, 13, 14 when an air pressure abnormality is detected in a first wheel (e.g., the left front wheel 11) among the plurality of wheels 11, 12, 13, 14, in order to raise a portion of the vehicle body where the first wheel 11 is disposed relative to the other wheels 12, 13, 14 among the plurality of wheels 11, 12, 13, 14 other than the first wheel 11 by utilizing an anti-squat force acting from a suspension device. This will be described in detail below.

[0036] When the vehicle 1 starts, first, the air pressure sensors 31, 32, 33, 34 start monitoring the air pressure (step S11). Then, for example, if one of the four wheels 11, 12, 13, 14, for example the left front wheel 11, gets a flat tire while the vehicle 1 is running, the left front wheel 11 deforms due to a sudden drop in air pressure, and the diameter of the left front wheel 11 decreases, as shown in FIG. 6. When the diameter of the left front wheel 11 decreases, the amount of movement of the left front wheel 11 relative to the number of rotations of the motor 21 decreases, so that a predetermined braking force F0 is generated on the left front wheel 11, and the left front part of the vehicle body 2 inclines so as to sink by the amount of the decrease in the diameter of the left front wheel 11. Specifically, the vehicle 1 inclines in the roll direction and the pitch direction based on the center of gravity G. Hereinafter, the inclination occurring in the roll direction among these inclinations is called the inclination R in the roll direction.

[0037] Since the air pressure sensors 31, 32, 33, and 34 start monitoring the air pressure in the left front wheel 11 in step S11, the air pressure in the left front wheel 11 is monitored by the air pressure sensor 31. When it is detected that the air pressure in the left front wheel 11 falls below the threshold value TH at a certain time T1 due to a puncture in the left front wheel 11 (Yes in step S12), the air pressure sensor 31 notifies the ECU 3 that an abnormality in the air pressure has occurred in the left front wheel 11.

[0038] The ECU 3, which has received the notification that an air pressure abnormality has occurred in the left front wheel 11, notifies the occupant of the occurrence of the air pressure abnormality by displaying a message on the instrument panel or sounding an alarm, and estimates the inclination of the vehicle body 2 caused by the air pressure abnormality (step S13). Specifically, the amount of inclination of the vehicle body 2 is estimated by detecting the amount of deformation of the left front wheel 11. The amount of deformation of the left front wheel 11 can be detected, for example, by utilizing the output of a sensor (not shown) capable of detecting the number of rotations of the wheel.

[0039] Once the amount of tilt of the vehicle body 2 has been estimated, the ECU 3 then calculates an anti-squat force required to offset at least a portion of the tilt amount of the vehicle body 2, the tilt R in the roll direction of the vehicle (step S14). Here, the wheels whose height of the vehicle body 2 is adjusted using the anti-squat force may be wheels other than the punctured left front wheel 11, more specifically the right front wheel 12, the left rear wheel 13, and the right rear wheel 14. Therefore, in this step S14, the ECU 3 calculates an anti-squat force FX 12 , FX 13 , FX 14 Estimate.

[0040] Required Anti-Squat Force FX 12 , FX 13 , FX 14 When the estimation is completed, the ECU 3 determines the distribution amount of the driving force to the three motors 22, 23, 24 that rotate and drive the right front wheel 12, the left rear wheel 13, and the right rear wheel 14 based on the estimation result. For example, as shown in FIG. 5, the distribution amount of the driving force is determined as follows: 12 The motor 24 of the right rear wheel 14 is applied with a driving force F 14 The driving force F described above may be distributed to the motors 22 and 24. 12 , F 14 When the anti-squat force FX 12 , FX 14 Therefore, the portion of the vehicle body 2 where the left front wheel 11 is disposed can be raised relative to the other wheels.

[0041] Here, the left rear wheel 13 is applied with a driving force F acting in the forward direction in order to maintain the propulsive force of the left side of the vehicle 1 that has been reduced due to the puncture of the left front wheel 11. 13 On the other hand, no driving force is distributed to the motor 21 of the punctured left front wheel 11. This is because it is difficult to stably control a punctured wheel, and it is difficult to obtain the desired anti-squat force, etc.

[0042] When the adjustment of the distribution amount of the driving force to the three motors 22, 23, 24 is completed, the ECU 3 executes a distribution command of the driving force, for example, at time T2 when a predetermined time has elapsed from time T1 (step S15). 12 , F 13 , F 14 When the force is distributed, an anti-squat force FX 12 , FX 14 This generates a force R1 that tilts in the opposite direction to the above-mentioned roll direction tilt R. This force R1 at least partially offsets the roll direction tilt R generated in the vehicle body 2, stabilizing the posture of the vehicle body 2 in the roll direction.

[0043] In the above embodiment, the case where the air pressure abnormality occurs in the left front wheel 11 is illustrated, but the same driving force adjustment may be performed when the air pressure abnormality occurs in another wheel. In the vehicle attitude control method according to this embodiment, even if the air pressure abnormality occurs in any wheel, the amount of distribution of the driving force is adjusted so that the two wheels located on the left-right opposite side of the wheel where the air pressure abnormality occurs are displaced in a direction in which the vehicle body 2 sinks by the anti-squat force. Therefore, the direction of the driving force distributed to the two wheels located on the left-right opposite side of the wheel where the air pressure abnormality occurs is always the same regardless of the punctured wheel, and also in the second and third embodiments described below.

[0044] As described above, according to the vehicle attitude control method of this embodiment, at least a part of the tilt R in the roll direction caused by an abnormality in the air pressure of one wheel can be offset by the anti-squat force obtained by adjusting the amount of distribution of the driving force to the other wheels. Therefore, it is possible to suppress the occurrence of the occupants of the vehicle 1 falling over or the load shifting. Furthermore, when reducing or eliminating the tilt of the vehicle body caused by an abnormality in the air pressure of the wheels, there is no need to separately provide a vehicle height adjustment function such as an active suspension, and this can be achieved by a simple control of the distribution of the driving force, so that the suspension system of the vehicle can be simplified.

[0045] <Second embodiment> When one wheel is punctured, not only the tilt in the roll direction of the vehicle body 2 as described above but also a yaw moment is generated in the vehicle 1. Such a yaw moment makes it difficult to maintain a normal running trajectory and may cause a traffic accident. Therefore, hereinafter, as a second embodiment of the present disclosure, a vehicle attitude control method capable of suppressing the yaw moment generated by a puncture in addition to the tilt in the roll direction will be exemplarily described with reference mainly to Figs. 8 to 10.

[0046] The vehicle attitude control method according to this embodiment may be similar to the vehicle attitude control method according to the above-mentioned first embodiment, except that a yaw rate for offsetting the yaw moment caused by a flat tire is calculated. Therefore, the following description will focus on processes that are different from the vehicle attitude control method according to the first embodiment, and steps similar to those in the vehicle attitude control method according to the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0047] In the vehicle attitude control method according to this embodiment, as shown in Fig. 8, when an abnormality in the air pressure of a first wheel, for example, the left front wheel 11, is detected (Yes in step S12), the inclination of the vehicle body is estimated (step S13) and the necessary anti-squat force is calculated (step S14). In parallel with steps S13 and S14, the yaw moment Y generated in the vehicle body 2 due to the abnormality in the air pressure of the left front wheel 11 is detected (step S23). The yaw moment Y generated in the vehicle body 2 can be detected by calculation from, for example, the driving force, braking force, lateral force, and torque generated in each of the wheels 11, 12, 13, and 14, the average trajectory of the vehicle 1, and the like. In this embodiment, since the left front wheel 11 is punctured, the yaw moment Y is generated in a direction rotating to the left (counterclockwise in Fig. 1).

[0048] Once the yaw moment Y occurring in the vehicle body 2 is detected, a yaw rate required to compensate (or cancel out) the detected yaw moment is calculated (step S24). Then, in order to obtain the calculated yaw rate, the driving force to be distributed to the motors 22, 23, 24 which rotate and drive the wheels 12, 13, 14 other than the left front wheel 11 is specified. In order to cancel out the yaw moment Y occurring in the vehicle body 2, it is particularly effective to temporarily increase the driving force of the motor 23 which rotates and drives the left rear wheel 13. Note that the term "temporarily" used here may refer to the period until the yaw rate of the vehicle body stabilizes to the same level as before the left front wheel 11 was punctured.

[0049] Next, in order to raise the portion of the vehicle body 2 located on the left front wheel 11 side relative to the other wheels 12, 13, 14 and to obtain the required yaw rate described above, a step of distributing driving force to the motors 22, 23, 24 which rotate and drive the other wheels 12, 13, 14 is executed (step S25). Specifically, based on the driving force specified in step S24 based on the required yaw rate and the driving force specified in step S14 based on the required anti-squat force, the ECU 3 determines the distribution amount of the final driving force to be distributed to each of the motors 22, 23, 24. Then, the ECU 3 calculates the determined final driving force F 22 , F 23 , F 24 Execute the distribution command.

[0050] Each of the motors 22, 23, and 24 is applied with a predetermined driving force F 22 , F 23 , F 24 When the driving force F is distributed to the vehicle body 2, as shown in FIG. 10, a force R2 is generated in the vehicle body 2, which tilts the vehicle body 2 in the opposite direction to the roll tilt R caused by the puncture of the left front wheel 11, due to the anti-squat force acting particularly on the right side of the vehicle body 2. This force R2 at least partially offsets the roll tilt R generated in the vehicle body 2, and the posture of the vehicle body 2 in the roll direction is stabilized. In addition, the driving force F 22 , F 23 , F 24 The right front wheel 12, the left rear wheel 13, and the right rear wheel 14 are rotationally driven by this, generating a force Y1 in the opposite direction to the yaw moment Y that rotates the vehicle leftward due to the puncture of the left front wheel 11. This force Y1 at least partially offsets the yaw moment Y generated in the vehicle body 2, and the attitude of the vehicle body in the yaw direction can also be stabilized.

[0051] As described above, according to the vehicle attitude control method of this embodiment, at least a part of the tilt R in the roll direction caused by an air pressure abnormality in one wheel can be offset by the anti-squat force obtained by adjusting the distribution amount of the driving force to the other wheels. In addition, at least a part of the yaw moment Y caused by an air pressure abnormality in one wheel can also be offset by distributing a predetermined distribution amount of the driving force to the other wheels. From the above, it is possible to further stabilize the attitude of the vehicle when an air pressure abnormality occurs in a wheel.

[0052] <Third embodiment> In the above-mentioned second embodiment, the necessary anti-squat force and yaw rate are obtained by adjusting the distribution amount of the driving force distributed to the motors 22, 23, 24 of the other wheels 12, 13, 14 for which no abnormal air pressure has been detected. However, there are other methods for ensuring the necessary yaw rate than adjusting the distribution amount of the driving force of the motors 22, 23, 24. Therefore, hereinafter, as a third embodiment of the present disclosure, a vehicle attitude control method that suppresses the yaw moment caused by a puncture by using a plurality of methods in addition to suppressing the tilt in the roll direction will be exemplarily described mainly with reference to Figs. 11 to 14.

[0053] In order to realize the vehicle attitude control method of this embodiment, the ECU 3 of the vehicle 1 to which the vehicle attitude control method of this embodiment is applied may be communicatively connected to the braking device 4 and the steering device 5 in addition to the motors 21, 22, 23, 24 and the air pressure sensors 31, 32, 33, 34, as shown in FIG. 11.

[0054] The braking device 4 may be a device capable of operating brakes, such as drum or disk brakes, attached to the wheels 11, 12, 13, and 14. The steering device 5 may be a device capable of rotating a steering wheel. It is preferable that the vehicle 1 of this embodiment is one in which the braking operation by the braking device 4 and the steering operation by the steering device 5 can be performed by a control signal from the ECU 3, as in a vehicle equipped with an automatic driving function.

[0055] The vehicle attitude control method according to this embodiment may be similar to the vehicle attitude control method according to the above-mentioned second embodiment, except that the braking device 4 and the steering device 5 are operated in addition to distributing the driving force when obtaining the required yaw rate. Therefore, the following description will focus on processes that are different from the vehicle attitude control method according to the second embodiment, and steps that are similar to those in the vehicle attitude control method according to the second embodiment will be given the same reference numerals and their description will be omitted.

[0056] 12, in the vehicle attitude control method according to this embodiment, when an abnormality in the air pressure of a first wheel, for example the left front wheel 11, is detected (Yes in step S12), the inclination of the vehicle body is estimated (step S13) and the necessary anti-squat force is calculated (step S14), and in parallel, the yaw moment Y generated in the vehicle body 2 is detected (step S23) and the necessary yaw rate is calculated (step S24). Then, to obtain the yaw rate calculated in step S24, three adjustments are made: the driving force distributed to the motors 22, 23, 24 that rotate and drive the wheels 12, 13, 14 other than the left front wheel 11, the braking operation using the braking device 4, and the steering operation using the steering device 5.

[0057] A braking operation using the braking device 4, for example, braking the right front wheel 12 and the right rear wheel 14, can reduce the yaw moment Y along the left direction. Also, a steering operation using the steering device 5, for example, steering the right front wheel 12 to the right (see FIG. 14), can reduce the yaw moment Y along the left direction. Here, it is preferable that the braking force from the braking device 4 and the steering from the steering device 5 are not applied to the punctured left front wheel 11. This is because, for example, the desired braking force and steering operation are not necessarily reflected in a punctured wheel, which may impair the stability of the vehicle 1 when it travels.

[0058] Next, in order to raise the portion of the vehicle body 2 located on the left front wheel 11 side relative to the other wheels 12, 13, 14 and to obtain the required yaw rate, driving force is distributed to the motors 22, 23, 24 which rotate and drive the other wheels 12, 13, 14, and the braking device 4 and steering device 5 are operated (step S35). Specifically, first, the ECU 3 determines the distribution amount of the final driving force to be distributed to each motor 22, 23, 24 based on the driving force specified based on the required yaw rate in step S24 and the driving force specified based on the required anti-squat force in step S14. Then, the ECU 3 calculates the determined final driving force F 32 , F 33 , F 34At the same time, the brake command for the braking device 4 and the steering command for the steering device 5 adjusted in step S24 are executed.

[0059] Each of the motors 22, 23, and 24 is applied with a predetermined driving force F 32 , F 33 , F 34 When the driving force F is distributed to the vehicle body 2, as shown in FIG. 10, a force R3 is generated in the vehicle body 2, which tilts the vehicle body 2 in the opposite direction to the roll tilt R caused by the puncture of the left front wheel 11, due to the anti-squat force acting particularly on the right side of the vehicle body 2. This force R3 at least partially offsets the roll tilt R generated in the vehicle body 2, and the posture of the vehicle body 2 in the roll direction is stabilized. In addition, the driving force F 32 , F 33 , F 34 The right front wheel 12, the left rear wheel 13, and the right rear wheel 14 are driven to rotate by the tire, generating a force Y2 in the opposite direction to the yaw moment Y that rotates the vehicle to the left, which is generated by the puncture of the left front wheel 11. This force Y2 at least partially offsets the yaw moment Y generated in the vehicle body 2, and the attitude of the vehicle body in the yaw direction can also be stabilized. In addition, the braking operation by the braking device 4 and the steering operation by the steering device 5 are performed to reduce the yaw moment Y generated in the vehicle body 2, and the driving force F 32 , F 33 , F 34 The force Y2 based on the force F can be smaller than the force Y1 obtained in the second embodiment. 32 , F 33 , F 34 The amount of distribution of the driving force R can be made to better reflect the driving force specified in step S14, and the tilt R in the roll direction can be effectively offset.

[0060] As described above, according to the vehicle attitude control method of this embodiment, the same effects as those described in the second embodiment can be expected. In addition, by using the braking device 4 and the steering device 5, the vehicle attitude can be further stabilized. Note that in this embodiment, in order to obtain the required yaw rate, a command is generated to operate both the braking device 4 and the steering device 5 in addition to the driving force, but it is also possible to operate only one of the braking device 4 or the steering device 5.

[0061] The present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present disclosure, all of which are included in the technical concept of the present disclosure.

[0062] The control unit and the method described in the present disclosure may be realized by a special-purpose computer having a processor programmed to execute one or more functions embodied in a computer program. Alternatively, the device and the method described in the present disclosure may be realized by a special-purpose computer having a processor configured by a dedicated hardware logic circuit. Alternatively, the device and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer. [Explanation of symbols]

[0063] 1 Vehicle 2 Vehicle body 3 ECU 4 Braking device 5 Steering device 11, 12, 13, 14 Wheels 21, 22, 23, 24 Motor (an example of a driving device) 31, 32, 33, 34 Air pressure sensor 41, 42, 43, 44 Suspension device

Claims

1. A method for controlling the attitude of a vehicle (1) including a plurality of wheels (11, 12, 13, 14) disposed at left and right positions at the front and rear of a vehicle body (2), drive devices (21, 22, 23, 24) that rotate and drive each of the plurality of wheels, and suspension devices (41, 42, 43, 44) that connect the vehicle body and the plurality of wheels so that predetermined anti-squat angles (θf, θr) are formed, comprising: A step (S12) of detecting an abnormality in air pressure of the plurality of wheels; and a step (S15) of distributing a driving force to the driving device that rotates and drives the other wheels to raise a portion of the vehicle body where the first wheel is disposed relative to the other wheels of the plurality of wheels excluding the first wheel by utilizing an anti-squat force acting by the suspension device when an air pressure abnormality is detected in a first wheel of the plurality of wheels. A method for controlling the attitude of a vehicle.

2. The step of distributing a driving force to the driving device includes: a step (S13) of detecting a deformation amount of the first wheel and estimating an amount of inclination of a vehicle body when an abnormality in air pressure is detected in the first wheel; and adjusting (S14) a distribution amount of driving force to the driving device that rotates the other wheel based on the estimated tilt amount. The vehicle attitude control method according to claim 1 .

3. The step of distributing a driving force to the driving device includes: A step (S23) of detecting a yaw moment generated in the vehicle body due to an abnormality in air pressure of the first wheel; A step (S24) of calculating a yaw rate required to compensate for the detected yaw moment; and (S25) distributing a driving force to the driving device that rotates and drives the other wheels in order to raise a portion of the vehicle body located on the first wheel side relative to the other wheels and to obtain the required yaw rate.

3. A method for controlling the attitude of a vehicle according to claim 1.

4. and a step (S35) of operating at least one of a braking device (4) and a steering device (5) to raise a portion of the vehicle body located on the first wheel side relative to the other wheels and to obtain the required yaw rate. The vehicle attitude control method according to claim 3.

5. The braking device brakes the other wheels, and the steering device steers the other wheels. The vehicle attitude control method according to claim 4.

6. At least one processor (51) of a computer included in a vehicle including a plurality of wheels disposed at the left and right positions at the front and rear of a vehicle body, a drive device that rotates and drives each of the plurality of wheels, and a suspension device that connects the vehicle body and the plurality of wheels so as to form a predetermined anti-squat angle, A process for detecting an abnormality in air pressure of the plurality of wheels; and when an air pressure abnormality is detected in a first wheel of the plurality of wheels, a process of distributing a driving force to the driving device that rotates and drives the other wheels in order to raise a portion of the vehicle body located on the side of the first wheel relatively to the other wheels of the plurality of wheels excluding the first wheel by utilizing an anti-squat force acting by the suspension device. Vehicle attitude control program.

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