Vehicle control device, vehicle control method, and vehicle control program

Abstract

To provide a vehicle control device that can set an appropriate steering upper limit for limiting a lateral acceleration of a vehicle to a certain value or lower.SOLUTION: A vehicle control device 10 controls steering of own vehicle 100. The vehicle control device sets a steering angle upper limit of the own vehicle, which limits a lateral acceleration of the own vehicle to a predetermined lateral acceleration or lower, based on a running state of the own vehicle, and controls steering of the own vehicle such that the steering angle of the own vehicle becomes the steering angle upper limit or lower.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device, a vehicle control method, and a vehicle control program for controlling the steering of a vehicle. [Background technology]

[0002] As a vehicle control device for controlling the steering of a vehicle, there is a known vehicle control device that suppresses abrupt changes in the steering angle of a vehicle by limiting the steering angle of the vehicle to below a certain steering angle (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-59429 [Overview of the project]

[0004] To ensure vehicle safety during driving, it is sometimes necessary to limit the vehicle's lateral acceleration to a certain value or less. In such cases, limiting the vehicle's steering angle to a certain value or less is an effective measure. Here, the upper limit of the vehicle's steering angle (steering angle limit) used to limit the steering angle to a certain value or less may be set based on the vehicle's specifications or the vehicle's steering angle zero point (the steering angle at which the vehicle is understood to be able to move in a straight line). However, vehicle specifications vary from vehicle to vehicle. Furthermore, the vehicle's steering angle zero point may deviate from the true steering angle zero point. For these reasons, the steering angle limit set based on the vehicle's specifications or the vehicle's steering angle zero point may be inappropriate for limiting the vehicle's lateral acceleration to a certain value or less.

[0005] The object of the present invention is to provide an appropriate method for limiting the lateral acceleration of a vehicle to a certain value or less. Rudder angle The objective is to provide a vehicle control device that allows setting an upper limit.

[0006] The vehicle control device according to the present invention includes a control device for controlling the steering of the vehicle. The control device is configured to set an upper limit of the steering angle of the vehicle, which is an upper limit of the steering angle of the vehicle that limits the lateral acceleration of the vehicle to a predetermined lateral acceleration or less, based on the driving state of the vehicle, and to control the steering of the vehicle so that the steering angle of the vehicle is less than or equal to the upper limit of the steering angle. Furthermore, the control device is configured to detect the yaw rate of the vehicle as the driving state using a yaw rate sensor, detect the vehicle's speed as the driving state using a vehicle speed detection device, detect the control steering angle, which is the steering angle of the vehicle, as the driving state using a steering angle sensor, calculate the maximum amount of steering angle that can increase the vehicle's steering angle from the current steering angle within a range where the vehicle's lateral acceleration does not exceed the predetermined lateral acceleration, based on the difference between the value obtained by multiplying the yaw rate by the driving speed and the predetermined lateral acceleration, and set the value obtained by adding the steering angle difference to the control steering angle as the upper limit of the steering angle.

[0007] As mentioned earlier, in order to limit the vehicle's lateral acceleration to a certain value, the upper limit of the steering angle is sometimes set based on the vehicle's specifications or the vehicle's steering angle zero point (the steering angle understood to be the angle at which the vehicle can move in a straight line). However, vehicle specifications vary from vehicle to vehicle. Also, the vehicle's steering angle zero point may deviate from the true steering angle zero point. For this reason, the upper limit of the steering angle set based on the vehicle's specifications or the vehicle's steering angle zero point may be inappropriate for limiting the vehicle's lateral acceleration to a certain value.

[0008] According to the vehicle control device of the present invention, the upper limit of the steering angle is set based on the driving state of the vehicle. The driving state of the vehicle is a state resulting from the reflection of the actual specifications of the vehicle and the actual zero point of the steering angle of the vehicle. Therefore, the upper limit of the steering angle set based on the driving state of the vehicle is appropriate for limiting the lateral acceleration of the vehicle to a certain value or less. Accordingly, by limiting the steering angle of the vehicle using the upper limit of the steering angle set in this way, the lateral acceleration of the vehicle can be appropriately limited to a certain value or less.

[0015] Furthermore, the vehicle control method according to the present invention is a method for controlling the steering of a vehicle, comprising the steps of: setting an upper limit value of the steering angle of the vehicle, which is an upper limit value of the steering angle of the vehicle that limits the lateral acceleration of the vehicle to a predetermined lateral acceleration or less, based on the driving state of the vehicle; and controlling the steering of the vehicle so that the steering angle of the vehicle is less than or equal to the upper limit value of the steering angle. Furthermore, the vehicle control method according to the present invention further includes the steps of: detecting the yaw rate of the vehicle as the driving state using a yaw rate sensor, detecting the driving speed of the vehicle as the driving state using a vehicle speed detection device, and detecting the control steering angle, which is the steering angle of the vehicle, as the driving state using a steering angle sensor; calculating the maximum amount of steering angle that can increase the steering angle of the vehicle from the current steering angle within a range in which the lateral acceleration of the vehicle does not become greater than the predetermined lateral acceleration, based on the difference between the value obtained by multiplying the yaw rate by the driving speed and the predetermined lateral acceleration, as the steering angle difference; and setting the value obtained by adding the steering angle difference to the control steering angle as the upper limit of the steering angle.

[0016] According to the vehicle control method of the present invention, for the same reasons as described above, the lateral acceleration of the vehicle can be appropriately limited to a certain value or less.

[0017] Furthermore, the vehicle control program according to the present invention is a program for controlling the steering of the vehicle, and is configured to set an upper limit value for the steering angle of the vehicle, which is an upper limit value for the steering angle of the vehicle that limits the lateral acceleration of the vehicle to a predetermined lateral acceleration or less, based on the driving state of the vehicle, and to control the steering of the vehicle so that the steering angle of the vehicle is less than or equal to the upper limit value for the steering angle. Furthermore, the vehicle control program according to the present invention is configured to detect the yaw rate of the vehicle as the driving state using a yaw rate sensor, detect the driving speed of the vehicle as the driving state using a vehicle speed detection device, detect the control steering angle, which is the steering angle of the vehicle, as the driving state using a steering angle sensor, calculate the maximum amount of steering angle that can increase the steering angle of the vehicle from the current steering angle within a range in which the lateral acceleration of the vehicle does not become greater than the predetermined lateral acceleration, based on the difference between the value obtained by multiplying the yaw rate by the driving speed and the predetermined lateral acceleration, and set the value obtained by adding the steering angle difference to the control steering angle as the upper limit of the steering angle.

[0018] According to the vehicle control program of the present invention, for the same reasons as described above, the lateral acceleration of the vehicle can be appropriately limited to a certain value or less.

[0019] The components of the present invention are not limited to the embodiments described below with reference to the drawings. Other objects, features, and incidental advantages of the present invention will be readily apparent from the description of the embodiments. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a diagram showing a vehicle control device according to an embodiment of the present invention. [Figure 2] Figure 2 is a flowchart showing the routines executed by a vehicle control device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0021] Hereinafter, a vehicle control device according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 shows a vehicle control device 10. The vehicle control device 10 is mounted on the vehicle 100. Hereinafter, the vehicle control device 10 will be described using the case where the operator of the vehicle 100 is a person who is riding in the vehicle 100 and driving the vehicle 100 (i.e., the driver of the vehicle 100) as an example.

[0022] However, the operator of the host vehicle 100 may be a person who remotely operates the host vehicle 100 without boarding the host vehicle 100 (i.e., the remote operator of the host vehicle 100). When the operator of the host vehicle 100 is a remote operator, the vehicle control device 10 is mounted on each of the host vehicle 100 and remote operation equipment installed outside the host vehicle 100 for remotely operating the host vehicle 100, and the functions of the vehicle control device 10 described below are shared and performed by the vehicle control device 10 mounted on the host vehicle 100 and the vehicle control device 10 mounted on the remote operation equipment, respectively.

[0023] Further, the vehicle control device 10 is also applicable to an autonomous vehicle (a vehicle in which the operation of the host vehicle 100 is automatically performed).

[0024] As shown in FIG. 1, the vehicle control device 10 includes an ECU (electronic control unit) 90 as a control device. The ECU 90 mainly includes a microcomputer. The microcomputer includes a CPU, a ROM, a RAM, a storage medium such as a nonvolatile memory, and an interface or the like. The CPU realizes various functions by executing instructions, programs, or routines stored in the storage medium. In particular, in the present example, the vehicle control device 10 stores a vehicle driving support program for executing steering control described later in the storage medium.

[0025] In addition, the vehicle control device 10 may be configured to be able to update (update) the vehicle driving support program by wireless communication with an external device (for example, Internet communication).

[0026] The vehicle control device 10 controls the steering of the host vehicle 100 by executing the routine shown in FIG. 2 at a predetermined calculation cycle. Therefore, at a predetermined timing, the vehicle control device 10 starts processing from step S200 of the routine shown in FIG. 2, advances the processing to step S205, and acquires the steering angle θ of the host vehicle 100.

[0027] As shown in Figure 1, the vehicle control device 10 is equipped with a steering angle sensor 20. The steering angle sensor 20 is a sensor that detects the rotation angle of the steering shaft of the vehicle 100. The rotation angle of the steering shaft is the angle by which the steering shaft rotates from its neutral position. The steering angle sensor 20 is electrically connected to the ECU 90. The ECU 90 (i.e., the vehicle control device 10) obtains the angle by which the steering shaft rotates from its neutral position as the steering angle θ using the steering angle sensor 20, and obtains the steering angle of the vehicle 100 requested by the driver as the driver-requested steering angle δdriver based on that steering angle θ.

[0028] Next, the vehicle control device 10 proceeds to step S210 and obtains (sets) the upper limit of the steering angle δgrd by calculation. The upper limit of the steering angle δgrd is used to limit the target value of the steering angle of the vehicle 100 (target steering angle δtgt), and the method of calculating it will be described later.

[0029] Next, the vehicle control device 10 proceeds to step S215 and determines whether the driver-requested steering angle δdriver is greater than the steering angle upper limit value δgrd.

[0030] If the vehicle control device 10 determines "Yes" in step S215, it proceeds to step S220, sets the upper limit of the steering angle δgrd as the target steering angle δtgt, and then proceeds to step S230. That is, the vehicle control device 10 limits the target steering angle δtgt to the upper limit of the steering angle δgrd.

[0031] As shown in Figure 1, the vehicle control device 10 is equipped with a steering device 60. The steering device 60 is a device that controls the steering angle of the vehicle 100 and is electrically connected to the ECU 90. The ECU 90 (i.e., the vehicle control device 10) can control the steering angle of the vehicle 100 by controlling the operation of the steering device 60.

[0032] When the vehicle control device 10 proceeds to step S230, it controls the operation of the steering device 60 so that the steering angle of the vehicle 100 becomes the target steering angle δtgt set in step S220, and then proceeds to step S295, terminating the processing of this routine.

[0033] As shown in Figure 1, the vehicle control device 10 is equipped with a steering angle sensor 30. The steering angle sensor 30 is a sensor that detects the steering angle of the vehicle 100 and is electrically connected to the ECU 90. The ECU 90 (i.e., the vehicle control device 10) obtains the steering angle of the vehicle 100 as a control steering angle δcur using the steering angle sensor 30. The vehicle control device 10 controls the operation of the steering device 60 so that the control steering angle δcur matches the target steering angle δtgt.

[0034] On the other hand, if the vehicle control device 10 determines "No" in step S215, it proceeds to step S225 and sets the current driver-requested steering angle δdriver as the target steering angle δtgt. Next, the vehicle control device 10 proceeds to step S230 and controls the operation of the steering device 60 so that the control steering angle δcur of the vehicle 100 becomes the target steering angle δtgt set in step S225, and then proceeds to step S295 to temporarily terminate the processing of this routine.

[0035] As a result, the steering of the vehicle 100 is controlled while limiting the steering angle of the vehicle 100 to below the upper limit of the steering angle δgrd, that is, while limiting the lateral acceleration of the vehicle 100 to below a certain value.

[0036] Next, we will explain how to calculate the upper limit of the rudder angle, δgrd.

[0037] If the driver-requested steering angle δdriver is large enough to cause a sideslip of the vehicle 100, it is preferable to set the target steering angle δtgt to a value that does not cause a sideslip of the vehicle 100, rather than setting the driver-requested steering angle δdriver as is. That is, it is preferable to set the target steering angle δtgt so that the lateral acceleration of the vehicle 100 is limited to a certain value or less. Therefore, the vehicle control device 10 sets an upper limit value δgrd for the steering angle as follows, and limits the target steering angle δtgt to that upper limit value δgrd.

[0038] The vehicle control device 10 obtains the steering angle difference Δδ by calculation based on equation 1 below, using the yaw rate ω, the vehicle speed V, the upper limit of lateral acceleration Ggrd, the stability factor A, the wheelbase L of the vehicle 100, and the gear ratio N of the vehicle 100. Then, as shown in equation 2 below, the vehicle control device 10 obtains the upper limit of steering angle δgrd by adding the steering angle difference Δδ to the current control steering angle δcur.

[0039] Δδ=(1+A·V 2 )·(L·N / V 2 )·(Ggrd-V·ω) …(1) δgrd = δcur + Δδ …(2)

[0040] Furthermore, the upper limit of lateral acceleration Ggrd is a default value (predetermined lateral acceleration) and is the upper limit of the allowable lateral acceleration of the vehicle 100. Also, the stability factor A, wheelbase L, and gear ratio N are also default values. In this example, if the true value of the stability factor A is unknown, it is preferable to set it to a value smaller than the actual stability factor of the vehicle 100, regardless of the type (vehicle model) of the vehicle 100.

[0041] As shown in Figure 1, the vehicle control device 10 is equipped with a yaw rate sensor 40 and a vehicle speed detection device 50. The yaw rate sensor 40 is a sensor that detects the yaw rate of the vehicle 100 and is electrically connected to the ECU 90. The ECU 90 (i.e., the vehicle control device 10) acquires the yaw rate of the vehicle 100 as yaw rate ω using the yaw rate sensor 40. The vehicle speed detection device 50 is a sensor that detects the driving speed of the vehicle 100 and is equipped with, for example, a wheel speed sensor. The vehicle speed detection device 50 is electrically connected to the ECU 90. The ECU 90 (i.e., the vehicle control device 10) acquires the driving speed of the vehicle 100 as vehicle speed V using the vehicle speed detection device 50.

[0042] In Equation 1, the yaw rate ω is the current yaw rate of the vehicle 100 detected by the yaw rate sensor 40, and is a value that represents the driving state of the vehicle 100. Also in Equation 1, the vehicle speed V is the detected value of the current driving speed of the vehicle 100 detected by the vehicle speed detection device 50, and is a value that represents the driving state of the vehicle 100.

[0043] In this example, the yaw rate ω (detected value of the yaw rate of the vehicle 100) and the vehicle speed V (detected value of the vehicle 100's speed) are used as the driving state of the vehicle 100 to obtain the upper limit of the steering angle δgrd. However, other detected values ​​representing the driving state of the vehicle 100 (in particular, other detected values ​​excluding the detected value of the vehicle 100's lateral acceleration) may also be used.

[0044] As mentioned earlier, in order to limit the vehicle's lateral acceleration to a certain value, the upper limit of the steering angle is sometimes set based on the vehicle's specifications or the vehicle's steering angle zero point (the steering angle understood to be the angle at which the vehicle can move in a straight line). However, vehicle specifications vary from vehicle to vehicle. Also, the vehicle's steering angle zero point may deviate from the true steering angle zero point. For this reason, the upper limit of the steering angle set based on the vehicle's specifications or the vehicle's steering angle zero point may be inappropriate for limiting the vehicle's lateral acceleration to a certain value.

[0045] According to the vehicle control device 10, the upper limit of the steering angle δgrd is set based on the yaw rate ω and the vehicle speed V, without using the lateral acceleration of the vehicle 100. Here, the yaw rate ω is a value that changes according to the steering angle of the vehicle 100 and is correlated with the lateral acceleration of the vehicle 100. The vehicle speed V is a value that affects the lateral acceleration of the vehicle 100. Therefore, by setting the target steering angle δtgt so that the steering angle (control steering angle δcur) of the vehicle 100 is limited to less than or equal to the upper limit of the steering angle δgrd, the lateral acceleration of the vehicle 100 can be appropriately limited to less than or equal to a certain value. The reason for this will be explained below.

[0046] If the estimated current steering angle of vehicle 100 is denoted as the estimated steering angle δcur_cal, then the estimated steering angle δcur_cal can be expressed by the following equation 3. In equation 3, "Gcur" is the current lateral acceleration of vehicle 100, and "δ0" is the steering angle (zero point of steering angle) that is understood to cause vehicle 100 to move in a straight line.

[0047] δcur_cal=(1+A·V 2 )·L·(Gcur / V 2 )·N+δ0…(3)

[0048] Furthermore, the current lateral acceleration Gcur of the vehicle 100 can be expressed by the following equation 4.

[0049] Gcur = V·ω …(4)

[0050] Therefore, from equations 3 and 4, the estimated rudder angle δcur_cal can be expressed by the following equation 5.

[0051] δcur_cal=(1+A·V 2 )·L·(V·ω / V 2 )·N+δ0…(5)

[0052] On the other hand, if the theoretical value of the upper limit of the rudder angle corresponding to the upper limit of the lateral acceleration Ggrd is denoted as the theoretical upper limit of the rudder angle δgrd_cal, then the theoretical upper limit of the rudder angle δgrd_cal can be expressed by the following equation 6.

[0053] δgrd_cal = (1 + A·V 2 )·L·(Ggrd / V 2 )·N + δ0…(6)

[0054] Here, since the rudder angle difference Δδ is expressed by the following equation 7, equation 8 is derived from equations 3, equation 6 and equation 7. That is, the rudder angle difference Δδ is obtained by the calculation according to the following equation 8.

[0055] Δδ = δgrd_cal - δcur_cal …(7) Δδ = (1 + A·V 2 )·(L·N / V 2 )·(Ggrd - Gcur) …(8)

[0056] And as described above, since the following equation 9 holds between the current lateral acceleration Gcur, the vehicle speed V and the yaw rate ω of the host vehicle 100, equation 10 is derived from equations 8 and equation 9. That is, the above equation 1 is derived.

[0057] Gcur = V·ω …(9) Δδ = (1 + A·V 2 )·(L·N / V 2 )·(Ggrd - V·ω) …(10)

[0058] As mentioned earlier, in this example, if the true value of the stability factor A is unknown, it is preferable to set it to a value smaller than the actual stability factor A of the vehicle 100, regardless of the type (vehicle model) of the vehicle 100. In that case, the theoretical steering angle upper limit δgrd_cal deviates from the steering angle upper limit that truly corresponds to the lateral acceleration upper limit Ggrd, but does not exceed it. Also, the estimated steering angle δcur_cal deviates from the current true steering angle of the vehicle 100. However, since the steering angle difference Δδ is the difference between the theoretical steering angle upper limit δgrd_cal and the estimated steering angle δcur_cal, it roughly coincides with the difference between the steering angle upper limit that truly corresponds to the lateral acceleration upper limit Ggrd and the current true steering angle of the vehicle 100, regardless of the value of the true steering angle zero point. Therefore, as shown in Equation 11 below, the upper limit of the steering angle δgrd obtained by adding the steering angle difference Δδ to the control steering angle δcur roughly coincides with the upper limit of the steering angle that truly corresponds to the upper limit of the lateral acceleration Ggrd, and does not exceed it.

[0059] δgrd = δcur + Δδ …(11)

[0060] In this example, if the true value of the stability factor A is unknown, a value smaller than the actual stability factor A of the vehicle 100 is used. Therefore, the steering angle difference Δδ is smaller than the true steering angle difference. Consequently, the steering angle upper limit δgrd is smaller than the true steering angle upper limit. However, as the steering angle upper limit δgrd is repeatedly calculated according to this example, the steering angle upper limit δgrd becomes a value close to the true steering angle upper limit.

[0061] The above explains why an appropriate upper limit value for the rudder angle, δgrd, can be set using equations 1 and 2.

[0062] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be adopted within the scope of the present invention. [Explanation of Symbols]

[0063] 10...Vehicle control device, 20...Steering angle sensor, 30...Steering angle sensor, 40...Yaw rate sensor, 50...Vehicle speed detection device, 60...Steering device, 90...ECU

Claims

1. A vehicle control device equipped with a control device for controlling the steering of the vehicle, The control device is A steering angle limit value, which is the upper limit of the steering angle of the vehicle that limits the lateral acceleration of the vehicle to a predetermined lateral acceleration or less, is set based on the driving state of the vehicle. The steering of the vehicle is controlled so that the steering angle of the vehicle is less than or equal to the upper limit of the steering angle. It is structured in such a way. In a vehicle control system, The control device is The yaw rate of the vehicle is detected as the driving state by a yaw rate sensor, the driving speed of the vehicle is detected as the driving state by a vehicle speed detection device, and the control steering angle, which is the steering angle of the vehicle, is detected as the driving state by a steering angle sensor. Based on the difference between the value obtained by multiplying the yaw rate by the travel speed and the predetermined lateral acceleration, the maximum amount of steering angle that can increase the steering angle of the vehicle from the current steering angle within a range where the lateral acceleration of the vehicle does not exceed the predetermined lateral acceleration is calculated as the steering angle difference. The value obtained by adding the aforementioned steering angle difference to the control steering angle is set as the upper limit of the steering angle. It is structured in such a way. Vehicle control device.

2. A vehicle control method for controlling the steering of the vehicle, A step of setting a steering angle limit value, which is the upper limit value of the steering angle of the vehicle that limits the lateral acceleration of the vehicle to a predetermined lateral acceleration or less, based on the driving state of the vehicle, A step of controlling the steering of the vehicle so that the steering angle of the vehicle is less than or equal to the upper limit of the steering angle, A vehicle control method having, The process includes detecting the yaw rate of the vehicle as the driving state using a yaw rate sensor, detecting the vehicle's speed as the driving state using a vehicle speed detection device, and detecting the control steering angle, which is the steering angle of the vehicle, as the driving state using a steering angle sensor. A step of calculating the maximum amount of steering angle that can increase the steering angle of the vehicle from the current steering angle within a range in which the lateral acceleration of the vehicle does not become greater than the predetermined lateral acceleration, based on the difference between the value obtained by multiplying the yaw rate by the travel speed and the predetermined lateral acceleration, as the steering angle difference; A step of setting the value obtained by adding the steering angle difference to the control steering angle as the upper limit of the steering angle, A vehicle control method further comprising the above.

3. A vehicle control program for controlling the steering of the vehicle, A steering angle limit value, which is the upper limit of the steering angle of the vehicle that limits the lateral acceleration of the vehicle to a predetermined lateral acceleration or less, is set based on the driving state of the vehicle. The steering of the vehicle is controlled so that the steering angle of the vehicle is less than or equal to the upper limit of the steering angle. A vehicle control program configured as follows: The yaw rate of the vehicle is detected as the driving state by a yaw rate sensor, the driving speed of the vehicle is detected as the driving state by a vehicle speed detection device, and the control steering angle, which is the steering angle of the vehicle, is detected as the driving state by a steering angle sensor. Based on the difference between the value obtained by multiplying the yaw rate by the travel speed and the predetermined lateral acceleration, the maximum amount of steering angle that can increase the steering angle of the vehicle from the current steering angle within a range where the lateral acceleration of the vehicle does not exceed the predetermined lateral acceleration is calculated as the steering angle difference. The value obtained by adding the aforementioned steering angle difference to the control steering angle is set as the upper limit of the steering angle. A vehicle control program configured in such a way.

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