Vehicle attitude control method and vehicle attitude control program

Abstract

The present disclosure provides an attitude control method for a vehicle (1) including: a plurality of wheels (11, 12, 13, 14) respectively disposed at left and right positions at the front and rear of a vehicle body (2); drive devices (21, 22, 23, 24) for rotationally driving each of the plurality of wheels; and suspension devices (41, 42, 43, 44) for connecting the vehicle body and the plurality of wheels so as to form predetermined anti-squat angles (θf, θr). The method includes: a step (S12) for detecting an air pressure abnormality in the plurality of wheels; and a step (S15) in which, if an air pressure abnormality is detected in a first wheel among the plurality of wheels, a driving force is distributed to the drive devices for rotationally driving the other wheels among the plurality of wheels, excluding the first wheel, in order to relatively raise the portion of the vehicle body in which the first wheel is disposed, with respect to the other wheels, by using an anti-squat force exerted by the suspension device.

Description

Vehicle attitude control method and vehicle attitude control program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from Patent Application No. 2023-096534, filed June 12, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a vehicle attitude control method and a vehicle attitude control program.

[0003] If a wheel puncture occurs while a vehicle is in motion, it becomes difficult to maintain a normal running trajectory, increasing the possibility of an accident. For this reason, technologies are being developed to allow vehicles to continue driving safely even if a wheel puncture occurs while in motion.

[0004] For example, Patent Document 1 below 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.

[0005] US Patent Application Publication No. 2021 / 0206383

[0006] When the air pressure of one wheel drops significantly due to a puncture or other reason, the diameter of the contact patch of that wheel becomes smaller than that of the other wheels. This not only generates the yaw moment described above in the vehicle, but also causes the vehicle body to partially sink as the punctured wheel collapses, causing the vehicle to tilt primarily in the roll direction. This tilt in the roll direction can cause occupants to tip over or cargo to collapse. In particular, in self-driving vehicles, which have become increasingly practical in recent years, occupants are not always facing forward, so there is a high possibility that the occupants will tip over as described above.

[0007] Although the technology in Patent Document 1 discloses that the yaw moment caused by a flat tire is compensated for (or offset), it does not take into consideration the tilt of the vehicle caused by the flat tire, and therefore there is room for improvement in vehicle attitude control when a flat tire occurs.

[0008] The present disclosure aims to provide a vehicle attitude control method and program for stabilizing the attitude of a vehicle when an air pressure abnormality occurs in one of the wheels.

[0009] A vehicle attitude control method according to a first aspect of the present disclosure is a method for controlling the attitude of a vehicle including a plurality of wheels disposed on the left and right sides of the front and rear of a vehicle body, drive devices that rotationally drive each of the plurality of wheels, and suspension devices that connect the vehicle body and the plurality of wheels so as to form a predetermined anti-squat angle, the method including the steps of: detecting an abnormal air pressure in the plurality of wheels; and, when an abnormal air pressure in a first wheel of the plurality of wheels is detected, distributing driving force to the drive devices that rotationally drive the other wheels to raise the 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 the anti-squat force acting by the suspension device.

[0010] In the above-described vehicle attitude control method, when an air pressure abnormality occurs in one wheel, the anti-squat force is utilized to reduce or eliminate the tilt of the vehicle body, 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 occupants from falling over or cargo from shifting inside the vehicle.

[0011] 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 the steps of detecting the amount of deformation of the first wheel and estimating the amount of tilt of the vehicle body when an air pressure abnormality is detected in the first wheel, and adjusting the amount of driving force distributed to the drive unit that rotates and drives the other wheel based on the estimated amount of tilt.

[0012] A vehicle attitude control method according to a third aspect of the present disclosure is the vehicle attitude control method according to the first or second aspect, wherein the step of distributing driving force to the drive device includes the steps of detecting a yaw moment generated in the vehicle body due to abnormal air pressure in the first wheel, calculating a yaw rate required to compensate for the detected yaw moment, and 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.

[0013] 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 including a step of operating at least one of a braking device and a steering device 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.

[0014] 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.

[0015] A vehicle attitude control program according to a sixth aspect of the present disclosure causes at least one processor of a computer included in a vehicle including a plurality of wheels arranged at left and right positions at the front and rear of the vehicle body, drive units that rotationally drive each of the plurality of wheels, and suspension units that connect the vehicle body and the plurality of wheels so as to form a predetermined anti-squat angle, to execute the following processes: detecting an abnormal air pressure in the plurality of wheels; and, when an abnormal air pressure in a first wheel of the plurality of wheels is detected, distributing driving force to the drive units that rotationally drive 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 unit.

[0016] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. In the drawings, FIG. 1 is a schematic diagram illustrating an example of a vehicle on which a vehicle attitude control method according to a first embodiment of the present disclosure can be implemented. FIG. 2 is a schematic configuration diagram illustrating an example of a hardware configuration of a control system for the vehicle shown in FIG. 1. FIG. 3A is an explanatory diagram illustrating a state in which the vehicle shown in FIG. 1 is running normally, as viewed from above. FIG. 3B is an explanatory diagram illustrating a state in which the vehicle shown in FIG. 1 is running normally, as viewed from a side. FIG. 3C is an explanatory diagram illustrating a state in which the vehicle shown in FIG. 1 is running normally, as viewed from a front perspective. FIG. 4 is a flowchart illustrating an example of a vehicle attitude control method according to the first embodiment of the present disclosure. FIG. 5 is a graph illustrating an example of changes in various parts of the vehicle when the vehicle attitude control method shown in FIG. 4 is executed. FIG. 6A is an explanatory diagram illustrating a state in which the left front wheel of the vehicle shown in FIG. 3 has a flat tire, as viewed from above. FIG. 6B 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 a side perspective. FIG. 6C 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 a front perspective. FIG. 7A is an explanatory diagram showing a state in which the vehicle shown in FIG. 6 has undergone the vehicle attitude control method shown in FIG. 4, as viewed from an overhead perspective. FIG. 7B is an explanatory diagram showing a state in which the vehicle shown in FIG. 6 has undergone the vehicle attitude control method shown in FIG. 4, as viewed from a side perspective. FIG. 7C is an explanatory diagram showing a state in which the vehicle shown in FIG. 6 has undergone the vehicle attitude control method shown in FIG. 4, as viewed from a front perspective. FIG. 8 is a flowchart showing an example of a vehicle attitude control method according to a second embodiment of the present disclosure. FIG. 9 is a graph showing an example of changes in various parts of the vehicle when the vehicle attitude control method shown in FIG. 8 is executed. FIG. 10A is an explanatory diagram showing a state in which the vehicle shown in FIG. 6 has undergone the vehicle attitude control method shown in FIG. 8, as viewed from an overhead perspective. Fig. 10B is an explanatory diagram of the state after the vehicle attitude control method shown in Fig. 8 has been implemented on the vehicle shown in Fig. 6, as seen from a side perspective. Fig. 10C is an explanatory diagram of the state after the vehicle attitude control method shown in Fig. 8 has been implemented on the vehicle shown in Fig. 6, as seen from a front perspective. Fig. 11 is a schematic configuration diagram showing another example of the hardware configuration of the control system of the vehicle shown in Fig. 1.Fig. 12 is a flowchart showing an example of a vehicle attitude control method according to a third embodiment of the present disclosure. Fig. 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. Fig. 14A is an explanatory diagram showing a state of the vehicle shown in Fig. 6 after the vehicle attitude control method shown in Fig. 12 is executed, viewed from an upper perspective. Fig. 14B is an explanatory diagram showing a state of the vehicle shown in Fig. 6 after the vehicle attitude control method shown in Fig. 12 is executed, viewed from a side perspective. Fig. 14C is an explanatory diagram showing a state of the vehicle shown in Fig. 6 after the vehicle attitude control method shown in Fig. 12 is executed, viewed from a front perspective.

[0017] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. Note that the scope necessary for the explanation to achieve the object of the present disclosure will be schematically shown below, and the scope necessary for explaining the relevant parts of the present disclosure will be mainly explained, and the parts for which explanation is omitted will be considered to be publicly known technologies.

[0018] <First embodiment> A vehicle attitude control method according to a first embodiment of the present disclosure may be employed in a vehicle 1 such as an automobile as shown in FIG. 1 to control the attitude of the vehicle when an air pressure abnormality occurs in one of the wheels, more specifically, when a flat tire occurs.

[0019] As shown in FIG. 1 , vehicle 1 includes a vehicle body 2, a plurality of wheels 11, 12, 13, and 14 (four in this embodiment) disposed on the left and right sides of the front and rear of the vehicle body 2, respectively, and motors 21, 22, 23, and 24 as examples of drive devices that rotate and drive each of the plurality of wheels 11, 12, 13, and 14. Of these, vehicle body 2 may include a cabin or the like including seats for occupants such as a driver. Note that in FIG. 1 , only the outer edge of vehicle body 2 is illustrated to facilitate understanding of the suspension structure of vehicle 1. This same illustration also applies to FIGS. 3A , 6A , 7A , 10A , and 14A , which will be described later. In FIG. 1 , the traveling direction of vehicle 1 is indicated by arrow D1, and the direction indicated by arrow D1 is sometimes referred to as the forward direction, the direction opposite to the direction indicated by arrow D1 is sometimes referred to as the reverse direction, and the direction intersecting with arrow D1 is sometimes referred to as the left-right direction.

[0020] The wheels 11, 12, 13, and 14 may include two wheels, namely, 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.

[0021] The motors 21, 22, 23, and 24 may be, for example, in-wheel motors that are disposed inside the wheels 11, 12, 13, and 14 and that rotate and drive the wheels 11, 12, 13, and 14. Therefore, the motors 21, 22, 23, and 24 may be capable of rotating the wheels 11, 12, 13, and 14 that they rotate independently of the other wheels.

[0022] The vehicle 1 may also include at least one ECU (Electronic Control Unit) 3 as an example of an electronic control device for controlling various components including mainly the motors 21 , 22 , 23 , and 24 .

[0023] The ECU 3 may be capable of distributing driving force to at least the motors 21, 22, 23, and 24. The driving force 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 well-known computer. As shown in FIG. 2 , the ECU 3 configured by a well-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.

[0024] 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 various programs stored in the ROM 52 or the storage 54 and executing the programs using the RAM 53 as a work area. The processor 51 may be capable of controlling the motors 21, 22, 23, and 24 and performing various arithmetic processing in accordance with the programs.

[0025] 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.

[0026] The storage 54 may 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.

[0027] 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 also be connected to components other than those described above, and may include, for example, a display means in the instrument panel that notifies of abnormal air pressure in 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.

[0028] The vehicle 1 may also include an air pressure abnormality detection unit for detecting air pressure abnormalities, such as punctures, in the wheels 11, 12, 13, and 14. Specifically, the vehicle 1 may include a tire pressure monitoring system (TPMS). The TPMS may include air pressure sensors 31, 32, 33, and 34 provided in each of the wheels 11, 12, 13, and 14, respectively, capable of detecting air pressure abnormalities. These air pressure sensors 31, 32, 33, and 34 may be integrated with air valves or may be fixed inside the wheels. When the air pressure of each wheel 11, 12, 13, and 14 falls below a predetermined threshold 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 that wheel via wired or wireless communication.

[0029] In this embodiment, an example is shown in which air pressure abnormalities in the wheels 11, 12, 13, and 14 are detected by air pressure sensors 31, 32, 33, and 34. However, various sensors capable of detecting air pressure abnormalities can be used as the air pressure detection means of 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, and 34. 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.

[0030] 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 also includes Fig. 3A, which shows the vehicle 1 from above, Fig. 3B, which shows the vehicle 1 from the left side, and Fig. 3C, which shows the vehicle 1 from the front. The same applies to Figs. 6, 7, 10, and 14, which will be described later.

[0031] The suspensions 41, 42, 43, and 44 connect the vehicle body 2 and the wheels 11, 12, 13, and 14 to form predetermined anti-squat angles θf and θr. The suspensions 41, 42, 43, and 44 may include, for example, shock absorbers. The wheels 11, 12, 13, and 14 connected to the vehicle body 2 via the suspensions 41, 42, 43, and 44 having predetermined anti-squat angles θf and θr are rotatable about the base ends of the suspensions 41, 42, 43, and 44 when the vehicle 1 accelerates or decelerates. This rotational movement can change the distance between the wheels 11, 12, 13, and 14 and the vehicle body 2. The anti-squat angles θf (sometimes referred to as "anti-dive angles") of the suspensions 41 and 42 connected to the left front wheel 11 and the right front wheel 12 may be set to be substantially the same. 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 also be set to be substantially the same angle.

[0032] Regarding the vehicle 1 including the suspension devices 41, 42, 43, and 44 described above, the vertical forces acting between the vehicle body 2 and the wheels 11, 12, 13, and 14 due to the driving forces from the motors 21, 22, 23, and 24 will be briefly described below. １１ , F １２ , F １３ , F １４ When each wheel 11, 12, 13, 14 rotates due to the rotation of the wheels 11, 12, 13, 14, a vertical force is generated between each wheel 11, 12, 13, 14 and the vehicle body 2 by the suspension devices 41, 42, 43, 44. The vertical force generated between each wheel 11, 12, 13, 14 and the vehicle body 2, i.e., the 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 , FX１２ , FX １３ , FX １４ is shown as a positive value when the wheels 11, 12, 13, and 14 move in a direction approaching the vehicle body 2, i.e., upward, and as a negative value when they move in a downward direction. １１ , FX １２ is sometimes called the "anti-dive force."

[0033] 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 that moves the vehicle 1 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 to move the vehicle body 2 away from the left front wheel 11 and the right front wheel 12, i.e., in a direction to lift the vehicle body 2 upward. １１ , F １２ , F １３ , F １４ 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 １４By utilizing this, it is possible to adjust the tilt in the roll direction of the vehicle body 2 that occurs when a flat tire occurs.

[0034] The vehicle attitude control method according to this embodiment can be implemented in the vehicle 1 having the above-described configuration. The vehicle attitude control method according to this embodiment will be described below mainly with reference to Figures 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 perform 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.

[0035] The following description will exemplify an attitude 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 (e.g., the 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.

[0036] 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, and 14, and a step (S15) of distributing driving force to motors 22, 23, and 24 that rotate and drive the other wheels 12, 13, and 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, and 14, in order to raise the portion of the vehicle body where the first wheel 11 is located relative to the other wheels 12, 13, and 14 of the plurality of wheels 11, 12, 13, and 14 other than the first wheel 11 by utilizing an anti-squat force exerted by the suspension system. This will be described in detail below.

[0037] When the vehicle 1 starts, first, the air pressure sensors 31, 32, 33, 34 start monitoring the air pressure (step S11). If one of the four wheels 11, 12, 13, 14, for example the left front wheel 11, experiences a flat tire while the vehicle 1 is running, the left front wheel 11 will deform due to a sudden drop in air pressure, and its diameter will decrease, as shown in Figures 6A to 6C. If the diameter of the left front wheel 11 decreases, the amount of movement of the left front wheel 11 relative to the rotation speed of the motor 21 will decrease, and therefore a predetermined braking force F will be applied to the left front wheel 11. ０ At the same time, the left front portion of the vehicle body 2 tilts downward by the amount of the reduced diameter of the left front wheel 11. Specifically, the vehicle 1 tilts in both the roll direction and the pitch direction relative to the center of gravity G of the vehicle 1. Hereinafter, of these tilts, the one that occurs in the roll direction will be referred to as the roll direction tilt R.

[0038] Since air pressure monitoring by the air pressure sensors 31, 32, 33, and 34 has started in step S11, the air pressure of the left front wheel 11 is monitored by the air pressure sensor 31. When it is detected that the air pressure of the left front wheel 11 has fallen 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 abnormal air pressure has occurred in the left front wheel 11.

[0039] Upon receiving the notification that an air pressure abnormality has occurred in the left front wheel 11, the ECU 3 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 tilt of the vehicle body 2 caused by the air pressure abnormality (step S13). Specifically, the amount of tilt 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 using the output of a sensor (not shown) that can detect the number of rotations of the wheel.

[0040] Once the amount of tilt of the vehicle body 2 has been estimated, the ECU 3 then calculates the 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, 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 the anti-squat force FX to be applied to the right front wheel 12, the left rear wheel 13, and the right rear wheel 14. １２ , FX １３ , FX １４ Estimate.

[0041] Required anti-squat force FX １２ , FX １３ , FX １４ When the estimation of 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 by dividing the driving force F １２ The motor 24 of the right rear wheel 14 is applied with a driving force F １４ The driving force F １２ , F １４ When the force FX is distributed, the right side portion of the vehicle body 2 supported by the right front wheel 12 and the right rear wheel 14 is subjected to an 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.

[0042] 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 on 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, making it difficult to obtain the desired anti-squat force, etc.

[0043] 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 driving force distribution command, for example, at time T2, which is a predetermined time after time T1 (step S15). １２ , F １３ , F １４ When the force FX is distributed, the vehicle body 2 receives an anti-squat force FX acting particularly on the right side of the vehicle body 2, as shown in FIGS. 7A to 7C. １２ , FX １４ This generates a force R1 that tilts the vehicle body 2 in the opposite direction to the tilt R in the roll direction. This force R1 at least partially offsets the tilt R in the roll direction that has occurred in the vehicle body 2, stabilizing the posture of the vehicle body 2 in the roll direction.

[0044] Although the above-described embodiment illustrates a case where an air pressure abnormality occurs in the left front wheel 11, similar driving force adjustments may be performed when an air pressure abnormality occurs in another wheel. In the vehicle attitude control method according to this embodiment, regardless of which wheel experiences an air pressure abnormality, the amount of driving force distribution is adjusted so that the two wheels located laterally opposite the wheel with the air pressure abnormality are displaced in a direction that causes the vehicle body 2 to sink due to an anti-squat force, regardless of which wheel has a puncture, and this direction of the driving force distributed to the two wheels located laterally opposite the wheel with the air pressure abnormality is always the same in the second and third embodiments described below.

[0045] As described above, according to the vehicle attitude control method of this embodiment, at least a portion of the tilt R in the roll direction caused by an air pressure abnormality in one wheel can be offset by an anti-squat force obtained by adjusting the amount of drive force distributed to the other wheels. This makes it possible to prevent occupants from tipping over or cargo from shifting in the vehicle 1. Furthermore, when reducing or eliminating the vehicle body tilt caused by an air pressure abnormality in a wheel, there is no need to provide a separate vehicle height adjustment function such as an active suspension, and this can be achieved through simple control of drive force distribution, thereby simplifying the vehicle suspension system.

[0046] <Second Embodiment> When one wheel gets a flat tire, not only does the vehicle body 2 tilt in the roll direction as described above, but a yaw moment also occurs in the vehicle 1. Such a yaw moment makes it difficult to maintain a normal traveling trajectory and can be a cause of a traffic accident. Therefore, as a second embodiment of the present disclosure, a vehicle attitude control method that can suppress not only tilt in the roll direction but also the yaw moment caused by a flat tire will be described below as an example mainly with reference to Figures 8 to 10.

[0047] The vehicle attitude control method according to this embodiment may be similar to the vehicle attitude control method according to the first embodiment described above, except that a yaw rate is calculated to offset the yaw moment caused by a flat tire. Therefore, the following description will focus on processes that are different from the vehicle attitude control method according to the first embodiment, and steps that are similar to those in the vehicle attitude control method according to the first embodiment will be assigned the same reference numerals and will not be described again.

[0048] 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 vehicle body tilt is estimated (step S13) and the required 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 calculated, for example, from the driving force, braking force, lateral force, and torque generated in each wheel 11, 12, 13, and 14, as well as the average trajectory of the vehicle 1. In this embodiment, since the left front wheel 11 has a flat tire, the yaw moment Y is generated in a direction rotating left (counterclockwise in FIG. 1 ).

[0049] Once the yaw moment Y acting on the vehicle body 2 is detected, the yaw rate required to compensate for (or cancel out) the detected yaw moment is calculated (step S24). Then, to obtain the calculated yaw rate, the driving force to be distributed to the motors 22, 23, and 24 that rotate and drive the wheels 12, 13, and 14 other than the left front wheel 11 is specified. In order to cancel out the yaw moment Y acting on the vehicle body 2, it is particularly effective to temporarily increase the driving force of the motor 23 that rotates and drives the left rear wheel 13. Note that "temporarily" here may refer to the period until the yaw rate of the vehicle body stabilizes to a level similar to that before the left front wheel 11 was punctured.

[0050] 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, a process of distributing driving force to the motors 22, 23, 24 that rotate and drive the other wheels 12, 13, 14 is executed (process S25). Specifically, based on the driving force determined in process S24 based on the required yaw rate and the driving force determined in process S14 based on the required anti-squat force, the final amount of driving force to be distributed to each motor 22, 23, 24 is determined. Then, the ECU 3 calculates the determined final driving force F ２２ , F ２３ , F ２４ Execute the distribution command.

[0051] Each of the motors 22, 23, and 24 is supplied with a predetermined driving force F ２２ , F ２３ , F ２４ 10A to 10C, the vehicle body 2 is subjected to a force R2 that tilts in the opposite direction to the tilt R in the roll direction 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 tilt R in the roll direction caused in the vehicle body 2, stabilizing the posture of the vehicle body 2 in the roll direction. In addition, the vehicle body 2 is subjected to a driving force F ２２ , F ２３ , F ２４The right front wheel 12, the left rear wheel 13, and the right rear wheel 14 are rotationally driven by the puncture, generating a force Y1 in the direction opposite 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 cancels out the yaw moment Y that occurs in the vehicle body 2, and the attitude of the vehicle body in the yaw direction can also be stabilized.

[0052] As described above, according to the vehicle attitude control method of this embodiment, at least a portion of the tilt R in the roll direction caused by an air pressure abnormality in one wheel can be offset by an anti-squat force obtained by adjusting the amount of drive force distributed to the other wheels. In addition, at least a portion of the yaw moment Y caused by an air pressure abnormality in one wheel can also be offset by distributing a predetermined amount of drive force to the other wheels. As a result, the vehicle attitude can be further stabilized when an air pressure abnormality occurs in a wheel.

[0053] Third Embodiment In the second embodiment described above, the required anti-squat force and yaw rate were obtained by adjusting the amount of drive force distributed to the motors 22, 23, and 24 of the other wheels 12, 13, and 14 for which no abnormal air pressure has been detected. However, there are other ways to ensure the required yaw rate besides adjusting the amount of drive force distributed to the motors 22, 23, and 24. Therefore, below, as a third embodiment of the present disclosure, a vehicle attitude control method that suppresses tilt in the roll direction and also suppresses the yaw moment caused by a puncture using multiple techniques will be described as an example, mainly with reference to FIGS. 11 to 14 .

[0054] 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 Figure 11.

[0055] The braking device 4 may be a device capable of operating brakes, such as drum or disc brakes, attached to the wheels 11, 12, 13, and 14. The steering device 5 may be a device capable of rotating a steering wheel. Preferably, the vehicle 1 of this embodiment is a vehicle equipped with an automatic driving function, in which braking operation by the braking device 4 and steering operation by the steering device 5 can be performed by control signals from the ECU 3.

[0056] The vehicle attitude control method according to this embodiment may be similar to the vehicle attitude control method according to the second embodiment described above, except that, when obtaining the required yaw rate, the braking device 4 and the steering device 5 are operated in addition to distributing the driving force. 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 assigned the same reference numerals and will not be described again.

[0057] 12 , in the vehicle attitude control method according to this embodiment, when an abnormal air pressure is detected in a first wheel, for example, the left front wheel 11 (Yes in step S12), the inclination of the vehicle body 2 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, and 24 that rotate the wheels 12, 13, and 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.

[0058] A braking operation using the brake device 4, for example, by applying the brakes to the right front wheel 12 and the right rear wheel 14, can reduce the yaw moment Y along the left direction. Furthermore, a steering operation using the steering device 5, for example, by steering the right front wheel 12 to the right (see FIGS. 14A to 14C), can also reduce the yaw moment Y along the left direction. Here, it is preferable that the braking force from the brake device 4 and the steering operation 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 may not necessarily be applied to a punctured wheel, which could impair the stability of the vehicle 1 when it travels.

[0059] 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 that 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 final driving force distribution amount to be distributed to each motor 22, 23, 24 based on the driving force determined based on the required yaw rate in step S24 and the driving force determined 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 ３４ At the same time, the brake command to the braking device 4 and the steering command to the steering device 5 adjusted in step S24 are executed.

[0060] Each of the motors 22, 23, and 24 is supplied with a predetermined driving force F ３２ , F ３３ , F ３４ 10A to 10C, the vehicle body 2 is subjected to a force R3 that tilts it in the opposite direction to the tilt R in the roll direction 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 tilt R in the roll direction caused in the vehicle body 2, stabilizing the posture of the vehicle body 2 in the roll direction. In addition, the vehicle body 2 is subjected to a driving force F ３２ , F ３３ , F ３４The right front wheel 12, the left rear wheel 13, and the right rear wheel 14 are driven to rotate by the puncture of the left front wheel 11, and a force Y2 is generated in the opposite direction to the yaw moment Y that rotates the vehicle body 2 to the left, which is generated when the left front wheel 11 is punctured. This force Y2 at least partially cancels out 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, thereby reducing 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 above can be smaller than the force Y1 obtained in the second embodiment. ３２ , F ３３ , F ３４ The distribution amount can be made to better reflect the driving force identified in step S14, and the tilt R in the roll direction can be effectively offset.

[0061] As described above, the vehicle attitude control method according to this embodiment can be expected to achieve the same effects as those described in the second embodiment. In addition, the vehicle attitude can be further stabilized by using the braking device 4 and the steering device 5. 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.

[0062] The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure. All such modifications are within the scope of the present disclosure. The use of nouns and similar referents in connection with the description of this disclosure (particularly in connection with the following claims) shall be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

[0063] The controller and method described herein may be implemented by a special-purpose computer having a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and method described herein may be implemented by a special-purpose computer having a processor configured with dedicated hardware logic circuits. Alternatively, the apparatus and method described herein may be implemented by one or more special-purpose computers configured by a combination of a processor executing a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0064] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A method for controlling the attitude of a vehicle (1) comprising a plurality of wheels (11, 12, 13, 14) respectively 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 a predetermined anti-squat angle (θf, θr) is formed, the method comprising the steps of: detecting an abnormality in air pressure in the plurality of wheels (S12); and, when an abnormality in air pressure is detected in a first wheel of the plurality of wheels, 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 where the first wheel is arranged 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.

2. A vehicle attitude control method as described in claim 1, wherein the step of distributing driving force to the drive unit comprises the steps of: detecting the amount of deformation of the first wheel and estimating the amount of inclination of the vehicle body when an air pressure abnormality is detected in the first wheel (S13); and adjusting the amount of driving force distributed to the drive unit that rotates the other wheels based on the estimated amount of inclination (S14).

3. A vehicle attitude control method as described in claim 1 or claim 2, wherein the step of distributing driving force to the drive device comprises the steps of: detecting a yaw moment generated in the vehicle body due to an abnormality in air pressure of the first wheel (S23); calculating a yaw rate required to compensate for the detected yaw moment (S24); and distributing driving force to the drive device which 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 (S25).

4. The vehicle attitude control method according to claim 3, 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 side of the first wheel relative to the other wheels and to obtain the required yaw rate.

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

6. A vehicle attitude control program that causes at least one processor (51) of a computer equipped in a vehicle having a plurality of wheels arranged respectively 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 the following processes: 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, distributing 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.

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