WO2024048737A1

WO2024048737A1 - Driving assistance device

Info

Publication number: WO2024048737A1
Application number: PCT/JP2023/031864
Authority: WO
Inventors: 真由山本
Original assignee: 株式会社アドヴィックス
Priority date: 2022-08-31
Filing date: 2023-08-31
Publication date: 2024-03-07
Also published as: JP2024033871A

Abstract

An execution device 62 of a driving assistance device 60 executes constant speed control for adjusting a driving force indication value and a brake force indication value by means of feedback control based on a deviation between a vehicle body speed and a target vehicle body speed. When executing the constant speed control, the execution device 62 stores, in a storage device 63, an increased speed of the driving force indication value at a time point when leading wheels among front wheels 11 and rear wheels 12 of a vehicle 10 pass through a disturbance part. After the time point when the leading wheels have passed through the disturbance part, the execution device 62 executes driving force increasing control for increasing the driving force indication value at the increased speed stored in the storage device 63.

Description

Driving support device

The present invention relates to a driving support device that supports vehicle operation by a vehicle driver.

Patent Document 1 discloses a parking support device that supports parking of a vehicle. The device includes a storage unit that stores the driving force of the vehicle at a predetermined position on the travel route of the vehicle to the target parking position when the vehicle is parked at the target parking position by the driver's driving operation. When the device automatically parks the vehicle at the target parking position with the driving force stored in the storage unit, the device controls the vehicle using the driving force stored in the storage unit.

Japanese Patent Application Publication No. 2015-77862

When the vehicle is driven at low speed, the driving force of the vehicle is relatively small. Therefore, when a vehicle travels on a route that includes disturbances that increase running resistance when the wheels pass, such as bumps, sudden changes in road slope, or potholes, the wheels are prevented from passing through the disturbances. It may take some time.

A driving support device for solving the above problems includes a command unit that performs constant speed control that adjusts the driving force and braking force of the vehicle through feedback control based on the deviation between the vehicle body speed and the target vehicle body speed. , when the constant speed control is being carried out, a leading wheel, which is a wheel located in the traveling direction of the vehicle, among the front wheels and rear wheels of the vehicle, passes through a disturbance part that is present in the travel path of the vehicle. and a storage unit that stores an increase rate of the driving force of the vehicle at a time point. The command unit performs driving force increase control to increase the driving force of the vehicle at the increased speed stored in the storage unit after the time when the leading wheel passes the disturbance portion.

When the leading wheel passes the disturbance part by implementing constant speed control, the driving support device causes the storage unit to store the increasing speed of the driving force at the time the leading wheel passes the disturbance part. Then, the driving support device performs driving force increase control to increase the driving force of the vehicle at the increasing speed stored in the storage unit after the time when the leading wheel passes the disturbance portion. Compared to the case where constant speed control continues even after the leading wheels pass the disturbance area, by implementing driving force increase control, the vehicle's driving force increases to the point where it can resist the running resistance increased by the disturbance area. can be increased early. Therefore, the following wheels can quickly pass through the disturbance area.

Therefore, when the vehicle is traveling at low speed, the driving support device can quickly complete the passage of the disturbance portion of the trailing wheels of the vehicle.

FIG. 1 is a configuration diagram schematically showing a vehicle equipped with a driving support device according to an embodiment. FIG. 2 is a schematic diagram showing how the vehicle travels at low speed toward a parking position. FIG. 3 is a flowchart showing a processing routine executed by the execution device of the driving support device. FIG. 4 is a flowchart showing a processing routine executed by the execution device. FIG. 5 is a timing chart showing changes in various parameters when the vehicle travels at low speed toward the parking position.

Hereinafter, one embodiment of the driving support device will be described according to FIGS. 1 to 5. In the present embodiment, a case will be described in which a wheel passes over a step as an example in which the wheel passes through a disturbance portion that increases running resistance when the wheel passes.

FIG. 1 illustrates a portion of a vehicle 10 including a driving assistance device 60. As shown in FIG.
<Vehicle configuration>
The vehicle 10 includes front wheels 11 and rear wheels 12 as wheels. The vehicle 10 includes the same number of friction brakes 20 as wheels, a braking device 30, and a drive device 40. One friction brake 20 is provided for one wheel.

The plurality of friction brakes 20 each include a rotating body 21, a friction part 22, and a wheel cylinder 23. Since the rotating body 21 rotates together with the wheel, the friction brake 20 can apply braking force to the wheel by pressing the friction portion 22 against the rotating body 21. The higher the hydraulic pressure within the wheel cylinder 23, the greater the force that presses the friction portion 22 against the rotating body 21. That is, the higher the hydraulic pressure within the wheel cylinder 23, the greater the braking force applied to the wheel.

The brake device 30 includes a brake actuator 31 and a brake control section 32 that controls the brake actuator 31. The brake actuator 31 is configured to be able to adjust the hydraulic pressure within the plurality of wheel cylinders 23 individually.

The brake control unit 32 controls the braking force of the vehicle 10 by operating the brake actuator 31. The brake control unit 32 can communicate with the driving support device 60 via the in-vehicle network. For example, when the brake control unit 32 receives a braking force command value FbR, which is a command value of the braking force of the vehicle 10, from the driving support device 60, the brake control unit 32 operates the brake actuator 31 based on the braking force command value FbR.

The drive device 40 includes a power unit 41 and a drive control section 42 that controls the power unit 41. Power unit 41 has at least one of an engine and an electric motor as a power source for vehicle 10. In vehicle 10 , output torque of power unit 41 is transmitted to front wheels 11 . Note that the output torque of the power unit 41 may be transmitted to at least one of the front wheels 11 and the rear wheels 12.

The drive control unit 42 controls the driving force of the vehicle 10 by operating the power unit 41. The drive control unit 42 can communicate with the driving support device 60 via the in-vehicle network. For example, when the drive control unit 42 receives the driving force instruction value FdR, which is the instruction value of the driving force of the vehicle 10, from the driving support device 60, the drive control unit 42 operates the power unit 41 based on the driving force instruction value FdR.

<Vehicle detection system>
The detection system of the vehicle 10 includes a plurality of sensors. The plurality of sensors include the same number of wheel speed sensors 51 as wheels, longitudinal acceleration sensors 52, and brake switches 53. The plurality of wheel speed sensors 51 each detect the rotational speed of the corresponding wheel. The longitudinal acceleration sensor 52 detects the longitudinal acceleration of the vehicle 10. The brake switch 53 outputs a signal indicating whether or not the driver is operating the brake operating member 15. The brake operation member 15 is, for example, a brake pedal. The rotational speed of the wheel based on the detected value of the wheel speed sensor 51 is referred to as "wheel speed VW." The longitudinal acceleration based on the detected value of the longitudinal acceleration sensor 52 is referred to as "longitudinal acceleration GX." The driver's operation of the brake operation member 15 is also referred to as a "brake operation."

<Driving support device>
The driving support device 60 has a function of supporting the driver's vehicle operation. "Vehicle operation" here includes accelerator operation, braking operation, and steering operation. For example, the driving support device 60 has a support function that allows the vehicle 10 to automatically travel at low speed. Such a support function is used when parking the vehicle 10 at a parking position. The "low-speed running of the vehicle 10" herein refers to running the vehicle 10 at a speed of less than 10 km/h, for example. Furthermore, "automatic driving" refers to traveling of the vehicle 10 in a state where the vehicle speed of the vehicle 10 is adjusted on the vehicle 10 side.

The driving support device 60 includes a processing circuit 61. The processing circuit 61 includes an execution device 62 and a storage device 63. For example, execution device 62 is a CPU. The storage device 63 stores various control programs executed by the execution device 62. The execution device 62 transmits the driving force instruction value FdR to the drive control section 42 and the braking force instruction value FbR to the braking control section 32 when realizing the above support function.

The execution device 62 functions as a command section M11 and a target vehicle speed setting section M13 by executing the control program. The command section M11 and the target vehicle speed setting section M13 are functional sections for realizing the above-mentioned support function.

<Command Department>
The command unit M11 performs constant speed control to adjust the driving force and braking force of the vehicle 10 by feedback control based on the deviation between the vehicle body speed VS of the vehicle 10 and the target vehicle body speed VSTr. Feedback control is, for example, PID control or PI control. The vehicle speed VS is derived based on at least one of the wheel speeds VW of the plurality of wheels. The target vehicle speed VSTr is set to the above-mentioned speed of less than 10 km/h.

As shown in FIG. 2, a step 101 may exist on the travel route 100 of the vehicle 10. In this case, among the front wheels 11 and rear wheels 12, after the leading wheel, which is a wheel located in the traveling direction of the vehicle 10, gets over the step 101, the trailing wheel, which is a wheel that is not the leading wheel, gets over the step 101. . When the vehicle 10 is moving backward as in the example shown in FIG. 2, the rear of the vehicle 10 is the traveling direction of the vehicle 10, so the rear wheels 12 correspond to the leading wheels and the front wheels 11 correspond to the trailing wheels. On the other hand, when the vehicle 10 is moving forward, the forward direction of the vehicle 10 is the direction of movement of the vehicle 10, so the front wheels 11 correspond to the leading wheels and the rear wheels 12 correspond to the trailing wheels.

If the leading wheel contacts the step 101 during constant speed control, the running resistance of the vehicle 10 will be higher than before the leading wheel contacts the step 101, so if the driving force Fd of the vehicle 10 is small, The leading wheels may not be able to get over the step 101, and the vehicle 10 may stop. For example, the driving force Fd of the vehicle 10 is also the torque generated by the power unit 41. In this case, the command unit M11 increases the driving force command value FdR by feedback control using the deviation between the vehicle speed VS and the target vehicle speed VSTr as input. When the driving force Fd of the vehicle 10 increases with an increase in the driving force instruction value FdR, and the leading wheel gets over the step 101, the command unit M11 sets the driving force instruction value FdR at the time when the leading wheel gets over the step 101. The increasing speed ΔFdR of is stored in the storage device 63. That is, the storage device 63 corresponds to a "storage section" that stores the increased speed ΔFdR at the time when the leading wheel passes the step 101, which is an example of a disturbance section.

The command unit M11 implements driving force increase control to increase the driving force instruction value FdR at the increasing speed ΔFdR stored in the storage device 63 after the leading wheel has climbed over the step 101. Specifically, the command unit M11 starts the driving force increase control before the trailing wheel contacts the step 101.

Even if the driving force instruction value FdR is increased by implementing the driving force increase control, the trailing wheels may not easily get over the step 101. Therefore, when the trailing wheel has not gotten over the step 101 even though the elapsed time TM from the start of the driving force increase control exceeds the specified time TMth, the command unit M11 controls the increasing speed ΔFdR stored in the storage device 63 to Increase the driving force command value FdR at a high speed.

Note that after the constant speed control is interrupted and the driving force increase control is started, the driving force instruction value FdR continues to be increased. Therefore, the vehicle speed VS may exceed the target vehicle speed VSTr. Therefore, after starting the driving force increase control, the command unit M11 suppresses the deviation of the vehicle speed VS from the target vehicle speed VSTr by adjusting the braking force command value FbR.

Then, when the trailing wheels get over the step 101, the command unit M11 resumes constant speed control.
<Target vehicle speed setting section>
The target vehicle speed setting section M13 sets the target vehicle speed VSTr. The target vehicle speed setting unit M13 sets the first vehicle speed VS1 as the target vehicle speed VSTr before the trailing wheels get over the step 101, that is, before the trailing wheels pass the step 101 (disturbance section). The target vehicle speed setting unit M13 increases the target vehicle speed VSTr after the trailing wheels get over the step 101, that is, after the trailing wheels pass the step 101 (disturbance portion). Specifically, the target vehicle speed setting unit M13 gradually increases the target vehicle speed VSTr up to the second vehicle speed VS2. A vehicle speed higher than the first vehicle speed VS1 is set as the second vehicle speed VS2. Furthermore, when the vehicle 10 is stopped due to the driver's braking operation or the like, the target vehicle speed setting unit M13 sets the first vehicle speed VS1 as the target vehicle speed VSTr.

<Drive braking adjustment process>
With reference to FIG. 3, a processing routine showing the drive braking adjustment process executed by the execution device 62 to derive the driving force command value FdR and the braking force command value FbR will be described. A plurality of steps S11 to S35 of this processing routine are each executed by the execution device 62 functioning as the command unit M11.

If the execution device 62 determines that the execution conditions for the support function described above are satisfied, it repeatedly executes this processing routine every predetermined control cycle. For example, the execution device 62 detects when the driver performs an operation to turn on the above-mentioned support function, and when the driver starts operating the vehicle in order to park the vehicle 10 at a predetermined parking position. In some cases, it is determined that the execution condition is met.

In step S11, the execution device 62 determines whether the leading wheels of the vehicle 10 have climbed over the step 101.
With reference to FIG. 5, an example of a process for determining whether the leading wheel has climbed over the step 101 will be described. When the leading wheel contacts the step 101 while the execution device 62 is performing constant speed control, the vehicle 10 stops. That is, as shown in FIG. 5A, the vehicle speed VS becomes 0 (zero). In this case, since the vehicle speed VS is lower than the target vehicle speed VSTr, the execution device 62 increases the driving force instruction value FdR by feedback control as shown in FIG. 5(D). When the driving force Fd of the vehicle 10 exceeds the driving force required to make the leading wheels get over the step 101, the leading wheels get over the step 101. That is, the leading wheels begin to rotate. As a result, the vehicle 10 starts moving, so the vehicle body speed VS suddenly increases as shown in FIG. 5(A).

Therefore, the execution device 62 determines that the leading wheel has climbed over the step 101 when the following condition (A1) is satisfied during the implementation of the constant speed control. That is, the execution device 62 determines that the leading wheel has passed the step 101, which is an example of a disturbance section. Note that the determination increase speed is set to a value that allows it to be determined whether or not the vehicle body speed VS has suddenly increased. (A1) When the vehicle body speed VS becomes greater than 0 (zero) from a state where the vehicle body speed VS is 0 (zero), the increasing rate of the vehicle body speed VS is equal to or higher than the determined increasing rate.

Returning to FIG. 3, in step S11, if the execution device 62 determines that the leading wheel has climbed over the step 101 (YES), the execution device 62 moves the process to step S15. On the other hand, when the execution device 62 determines that the leading wheel has not climbed over the step 101 (S11: NO), the execution device 62 shifts the process to step S13.

Note that when the execution device 62 determines that the leading wheel has climbed over the step 101 by executing the above-described determination process, the execution device 62 determines that the leading wheel has climbed over the step 101 until the step section determination flag FLG, which will be described later, is switched from on to off. Continue to judge that 101 has been overcome.

In step S13, the execution device 62 implements constant speed control. Specifically, the execution device 62 derives the control amount through feedback control using the deviation between the vehicle speed VS and the target vehicle speed VSTr as input. This control amount is called "FB control amount." The execution device 62 derives a driving force instruction value FdR and a braking force instruction value FbR based on the FB control amount. For example, if the leading wheels cannot overcome the bump 101 and the vehicle speed VS is significantly lower than the target vehicle speed VSTr, the execution device 62 sets the braking force instruction value FbR to 0 (zero) by implementing feedback control. After holding the driving force command value FdR, the driving force command value FdR is increased. The execution device 62 transmits the driving force command value FdR to the drive control section 42 and transmits the braking force command value FbR to the brake control section 32. After transmitting the instruction values FdR and FbR, the execution device 62 temporarily ends this processing routine.

In step S15, the execution device 62 determines whether the step section determination flag FLG is set to OFF. The step section determination flag FLG is a flag for determining whether the vehicle 10 is traveling in a section where the step 101 exists. When the vehicle 10 is traveling in a section where a step 101 exists, the step section determination flag FLG is set to ON. When the vehicle 10 is traveling in a section where the step 101 does not exist or when the vehicle 10 passes through the section, the step section determination flag FLG is set to OFF. When the step section determination flag FLG is set to OFF (S15: YES), the execution device 62 moves the process to step S17. On the other hand, if the step section determination flag FLG is set to ON (S15: NO), the execution device 62 shifts the process to step S21.

In step S17, the execution device 62 causes the storage device 63 to store the increase rate ΔFdR of the current driving force instruction value FdR. That is, the execution device 62 causes the storage device 63 to store the increased speed ΔFdR at the time when it is determined that the leading wheel has climbed over the step 101. For example, the execution device 62 stores a value obtained by differentiating the driving force instruction value FdR with respect to time in the storage device 63 as the increasing speed ΔFdR. It can be said that the increasing speed ΔFdR stored in the storage device 63 is "the increasing speed of the driving force of the vehicle 10 at the time when the leading wheel passes a disturbance portion existing on the traveling route of the vehicle 10." Further, the feedback control in this example is PI control or PID control. Therefore, the longer the vehicle 10 does not start, the faster the increasing speed ΔFdR of the driving force instruction value FdR becomes. Therefore, compared to the case where the time required for the leading wheel to get over the step 101 is short because the step 101 is small, when the time required for the leading wheel to get over the step 101 is long because the step 101 is large, the storage The value of the increasing speed ΔFdR stored in 63 becomes larger.

Subsequently, in step S19, the execution device 62 sets the step section determination flag FLG to ON. After that, the execution device 62 moves the process to step S21.
In step S21, the execution device 62 determines whether a predetermined first time lag TL1 has elapsed from the time when it is determined that the leading wheel has climbed over the step 101. The time when it is determined that the leading wheel has climbed over the step 101 can also be said to be the time when the leading wheel has passed through the disturbance area. If the constant speed control is continued even after the leading wheels get over the bump 101, the vehicle speed VS increases. Therefore, the driving force instruction value FdR is decreased by feedback control. When the driving force instruction value FdR is decreased, the driving force Fd of the vehicle 10 is also decreased. The delay in response of the driving force Fd to the decrease in the driving force instruction value FdR can be grasped in advance from the specifications of the vehicle 10. Therefore, the length of time that takes such response delay into account is set as the first time lag TL1. If the first time lag TL1 has elapsed from the time when it is determined that the leading wheel has climbed over the step 101 (S21: YES), the execution device 62 shifts the process to step S23. On the other hand, if the first time lag TL1 has not elapsed since the time when it is determined that the leading wheel has climbed over the step 101 (S21: NO), the execution device 62 moves the process to step S13 and performs constant speed control.

In step S23, the execution device 62 determines whether the elapsed time TM from the reference time exceeds the specified time TMth. The reference point in time is the point in time when the first time lag TL1 has elapsed from the point in time when it is determined that the leading wheel has gotten over the step 101. The reference time can also be said to be the start time of driving force increase control, which will be described later. The execution time of the driving force increase control is set as the specified time TMth. The specified time TMth may be set based on the wheelbase length of the vehicle 10 and the target vehicle speed VSTr. If the elapsed time TM exceeds the specified time TMth (S23: YES), the execution device 62 moves the process to step S27. On the other hand, if the elapsed time TM is less than or equal to the specified time TMth (S23: NO), the execution device 62 shifts the process to step S25.

In step S25, the execution device 62 increases the driving force instruction value FdR at the increasing speed ΔFdR stored in the storage device 63. That is, step S25 corresponds to "driving force increase control". For example, the execution device 62 derives the sum of the product of the increasing speed ΔFdR and the cycle time TMc and the previous value of the driving force instruction value FdR as the latest value of the driving force instruction value FdR. The cycle time TMc is the length of the control cycle of this processing routine. The previous value of the driving force instruction value FdR is the driving force instruction value FdR derived when this processing routine was executed last time. The execution device 62 transmits the latest value of the derived driving force instruction value FdR to the drive control unit 42. Then, the execution device 62 moves the process to step S29.

In step S27, the execution device 62 increases the driving force instruction value FdR at a higher speed than the increasing speed ΔFdR stored in the storage device 63. For example, the execution device 62 derives the sum of the product of the increasing speed ΔFdR and the cycle time TMc, the previous value of the driving force instruction value FdR, and the predetermined offset driving force α as the latest value of the driving force instruction value FdR. do. A positive driving force is set as the offset driving force α. The execution device 62 transmits the latest value of the derived driving force instruction value FdR to the drive control unit 42. Then, the execution device 62 moves the process to step S29.

In step S29, the execution device 62 derives a braking force instruction value FbR to suppress deviation of the vehicle speed VS from the target vehicle speed VSTr. For example, the execution device 62 derives the braking force command value FbR based on feedback control using the deviation between the vehicle speed VS and the target vehicle speed VSTr as input. The feedback control performed here is, for example, PID control or PI control. The execution device 62 transmits the derived braking force instruction value FbR to the braking control unit 32. Thereby, the execution device 62 can suppress deviation of the vehicle body speed VS from the target vehicle body speed VSTr by adjusting the braking force instruction value FbR. After transmitting the braking force instruction value FbR, the execution device 62 moves the process to step S31.

In step S31, the execution device 62 determines whether the trailing wheels of the vehicle 10 have climbed over the step 101.
With reference to FIG. 5, an example of a process for determining whether the following wheels have climbed over the step 101 will be described. After starting the driving force increase control, the execution device 62 suppresses the vehicle speed VS from exceeding the target vehicle speed VSTr by adjusting the braking force Fb. The bump 101 is an obstacle to increasing the vehicle speed VS, so when the trailing wheels get over the bump 101, the vehicle speed VS temporarily decreases and rises, as at around timing t14 in FIG. 5. do. Therefore, when the execution device 62 detects a decrease or increase in the vehicle speed VS while adjusting the braking force Fb as described above, the execution device 62 determines that the trailing wheels have climbed over the step 101. For example, the execution device 62 determines that the trailing wheels have climbed over the step 101 when the rate of decrease in the vehicle body speed VS is equal to or higher than the determined rate of decrease. In this case, "the trailing wheels have climbed over the step 101" also includes "a state in which the trailing wheels are getting over the step 101 in a state where the trailing wheels are in contact with the step 101." On the other hand, if the rate of decrease in the vehicle body speed VS is smaller than the determined rate of decrease, the execution device 62 determines that the trailing wheels have not climbed over the step 101 . In this case, a decreasing speed at which it can be determined whether or not the vehicle body speed VS has started to decrease due to the following wheels overcoming the step 101 is set as the determined decreasing speed.

Returning to FIG. 3, in step S31, if the execution device 62 determines that the trailing wheel has climbed over the step 101 (YES), the process moves to step S33. On the other hand, if the execution device 62 determines that the following wheels have not climbed over the step 101 (S31: NO), it temporarily ends this processing routine.

In step S33, the execution device 62 determines whether a predetermined second time lag TL2 has elapsed from the overcoming point, which is the point in time when the determination in step S31 is switched from NO to YES. The overcoming point can also be said to be the time when it is determined that the following wheels have overcame the step 101. When the trailing wheels are climbing over a step, the vehicle speed VS is temporarily reduced. In this case, if a braking force is applied to the vehicle 10 based on the braking force instruction value FbR, the braking force instruction value FbR is decreased due to a decrease in the vehicle body speed VS. The length of time required for the vehicle speed VS to recover to a certain degree can be predicted to some extent from the specifications of the vehicle 10. Therefore, the second time lag TL2 is set to the length of time during which it can be determined whether the vehicle speed VS has recovered to some extent. If the second time lag TL2 has elapsed from the point of overcoming (S33: YES), the execution device 62 shifts the process to step S35. On the other hand, if the second time lag TL2 has not elapsed since the time of overcoming (S33: NO), the execution device 62 temporarily ends this processing routine.

In step S35, the execution device 62 sets the step section determination flag FLG to OFF. Then, the execution device 62 moves the process to step S13 and implements constant speed control.
<Target vehicle speed setting process>
Referring to FIG. 4, a processing routine showing the target vehicle speed setting process executed by the execution device 62 to set the target vehicle speed VSTr will be described. A plurality of steps S51 to S59 of this processing routine are each executed by the execution device 62 functioning as the target vehicle speed setting section M13. The execution device 62 repeatedly executes this processing routine every predetermined control cycle.

In step S51, the execution device 62 determines whether the vehicle 10 is stopped. For example, the execution device 62 determines whether the vehicle 10 is stopped based on the vehicle speed VS. When the execution device 62 determines that the vehicle 10 is stopped (S51: YES), the execution device 62 moves the process to step S55. On the other hand, when the execution device 62 determines that the vehicle 10 is not stopped (S51: NO), the execution device 62 moves the process to step S53.

In step S53, the execution device 62 determines whether the following wheels have climbed over the step 101, similarly to step S31 shown in FIG. When the execution device 62 determines that the following wheels have climbed over the step 101 (S53: YES), the execution device 62 moves the process to step S57. On the other hand, when the execution device 62 determines that the trailing wheel has not climbed over the step 101 (S53: NO), the execution device 62 moves the process to step S55.

In step S55, the execution device 62 sets the first vehicle speed VS1 as the target vehicle speed VSTr. Thereafter, the execution device 62 temporarily ends this processing routine.
In step S57, the execution device 62 derives the sum of the previous value of the target vehicle speed VSTr and the predetermined speed value dVS as the tentative target vehicle speed value VSTr1. The previous value of the target vehicle speed VSTr is the target vehicle speed VSTr derived when this processing routine was executed last time. In the next step S59, the execution device 62 derives the smaller of the tentative target vehicle speed VSTr1 and the second vehicle speed VS2 as the target vehicle speed VSTr. Thereafter, the execution device 62 temporarily ends this processing routine.

<Action and effect>
The operation and effects of the driving support device 60 will be explained with reference to FIGS. 2 and 5.
In this example, the driver performs a braking operation when the rear wheels 12 (leading wheels) contact the step 101 while the vehicle 10 is moving backward, so a braking force is applied to the vehicle 10. As a result, the vehicle 10 stops with the rear wheels 12 in contact with the step 101. In addition, in (C) of FIG. 5, the solid line shows the transition of the braking force FbS applied to the vehicle 10 by the driver's braking operation, while the broken line shows the transition of the braking force instruction value FbR or the braking force instruction value. It shows the transition of the braking force Fb of the vehicle 10 that is controlled according to FbR. Further, while the driver is performing a braking operation, the driving force command value FdR becomes 0 (zero), but the driving force Fd is a predetermined driving force (>0 (zero)).

As shown in FIG. 5, when the driver's braking operation is released at timing t11, constant speed control is started and the driving force instruction value FdR is increased from 0 (zero). However, since the rear wheel 12, which is the leading wheel, is in contact with the step 101, running resistance is large. As a result, vehicle 10 does not start. That is, the state in which the vehicle body speed VS is lower than the target vehicle body speed VSTr continues. Then, as shown in FIG. 5D, the driving force command value FdR is increased by feedback control. As the driving force instruction value FdR increases in this way, the driving force Fd of the vehicle 10 also increases.

At timing t12, the driving force Fd of the vehicle 10 exceeds the driving force required to make the rear wheels 12 get over the step 101, so the rear wheels 12 get over the step 101. Then, since the vehicle 10 starts moving, the vehicle body speed VS increases as shown in FIG. 5(A). Note that when it is determined that the rear wheel 12, which is the leading wheel, has climbed over the step 101, the step section determination flag FLG is set to ON, as shown in FIG. 5(E). Further, the increasing speed ΔFdR of the driving force instruction value FdR at timing t12 is stored in the storage device 63.

When the rear wheels 12 pass over the step 101, the driving force command value FdR is decreased and the braking force command value FbR is increased in order to prevent the vehicle speed VS from exceeding the target vehicle speed VSTr. Thereby, it is possible to suppress deviation of the vehicle body speed VS from the target vehicle body speed VSTr.

At timing t13, when the first time lag TL1 has elapsed from timing t12, constant speed control is ended and driving force increase control is started. That is, the driving force increase control is started before the trailing wheels reach the step 101, which is an example of a disturbance portion. Then, even if the vehicle speed VS is not less than the target vehicle speed VSTr, the driving force instruction value FdR is increased by the increased speed ΔFdR stored in the storage device 63. Thereby, the driving force Fd of the vehicle 10 can be increased at an early stage. Further, the driving force Fd can be increased at an increasing speed depending on the size of the step 101.

Here, a comparative example will be described in which constant speed control is continued even after the leading wheels get over the bump 101. In this case, since the vehicle speed VS is approximately equal to the target vehicle speed VSTr after the leading wheels have climbed over the step 101, the driving force instruction value FdR and the driving force Fd are relatively small. In this way, the trailing wheels come into contact with the step 101 while the driving force Fd is relatively small. Therefore, the following wheels may not be able to get over the step 101, and the vehicle 10 may come to a stop. Further, even if the vehicle 10 does not stop, there is a possibility that the vehicle body speed VS decreases to nearly 0 (zero). When constant speed control is being performed, the driving force instruction value FdR gradually increases after a deviation between the vehicle body speed VS and the target vehicle body speed VSTr begins to occur. As a result, it takes time for the trailing wheels to get over the step 101 due to the increase in the driving force Fd. If it takes time for the trailing wheels to get over the step 101, there is a risk that the driver will try to move the vehicle 10 quickly, which may induce the driver to perform an accelerator operation or a subsequent braking operation.

In this regard, in this embodiment, the driving force Fd can be increased even before the trailing wheel contacts the step 101. Therefore, compared to the comparative example, the trailing wheels can quickly overcome the step 101. Therefore, when the vehicle 10 is automatically traveling at low speed, the trailing wheels can quickly complete overcoming the step 101. Therefore, the vehicle 10 can be started promptly before the driver operates the accelerator in order to start the stopped vehicle 10. That is, it is possible to suppress unnecessary accelerator operations and braking operations by the driver when making the wheels go over the step 101.

In the example shown in FIG. 5, it is determined that the front wheels 11 have climbed over the step 101 at timing t14 while the driving force increase control is being performed. When the vehicle speed VS decreases when the wheels go over the step 101, the braking force command value FbR is immediately decreased. As a result, the already increased driving force Fd is quickly exerted in order for the wheels to overcome the step 101 on the installation surface of the driving wheels. Increasing the driving force instruction value FdR by the driving force increase control is performed from timing t14 to timing t15, which is the time when the second time lag TL2 has elapsed.

Constant speed control is restarted at timing t15. Then, the vehicle speed VS is controlled by adjusting the driving force Fd and the braking force Fb. In the example shown in FIG. 5, the braking force instruction value FbR is gradually reduced by switching to constant speed control. Further, as the braking force instruction value FbR decreases, the driving force instruction value FdR also decreases. When the driver starts a braking operation at timing t17 during the constant speed control, the braking force FbS is applied to the vehicle 10, so the vehicle 10 stops. That is, constant speed control is ended.

Note that the driving support device 60 can further obtain the following effects.
(1) Even if driving force increase control is started, the trailing wheels may have difficulty getting over the step 101. In this embodiment, if the trailing wheels have not climbed over the step 101 even at timing t16, which is a specified time TMth after timing t13, which is the start point of driving force increase control, the The driving force instruction value FdR is increased at a high speed. Thereby, the driving force Fd can be increased earlier than when the driving force increase control is continued. Therefore, it is possible to suppress the delay in the following wheels getting over the step 101.

(2) After the driving force increase control is started, the driving force instruction value FdR is increased regardless of whether the vehicle speed VS is less than the target vehicle speed VSTr, so the vehicle speed VS and the target vehicle speed There is a possibility that the deviation from VSTr will become large. In the present embodiment, during the period from the start of the driving force increase control until the constant speed control is restarted, the deviation of the vehicle body speed VS from the target vehicle body speed VSTr is suppressed by adjusting the braking force instruction value FbR. Ru. Thereby, when the vehicle 10 is automatically traveling in a section where the step 101 exists, it is possible to suppress the vehicle body speed VS from significantly exceeding the target vehicle body speed VSTr. Thereby, it is possible to suppress an increase in impact when the trailing wheels collide with the step 101 due to a significant increase in the vehicle speed VS.

(3) The driver does not need to operate the accelerator when making the wheels go over the step 101. Further, it is possible to suppress the driver from performing a braking operation to decelerate the vehicle 10 due to an excessive increase in the vehicle body speed VS due to the accelerator operation when the wheels go over a step.

(4) Note that when the vehicle 10 passes through a section where the step 101 exists, the target vehicle speed VSTr gradually increases. In the example shown in FIG. 5, the target vehicle speed VSTr is increased toward the second vehicle speed VS2 from timing t14. Thereby, the vehicle 10 can be quickly moved to a predetermined parking position.

<Example of change>
The above embodiment can be modified and implemented as follows. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

- It is not essential to increase the target vehicle speed VSTr after the trailing wheels get over the bump 101.
- The first vehicle speed VS1 and the second vehicle speed VS2 may be changed by the driver's operation.

- After starting the driving force increase control, the braking force command value FbR is varied according to the deviation between the vehicle body speed VS and the target vehicle body speed VSTr, but the invention is not limited to this. For example, the execution device 62 may maintain the braking force command value FbR at a predetermined value during the period from starting the driving force increase control to restarting the constant speed control.

- In the driving force increase control, the execution device 62 may increase the driving force command value FdR at an increasing speed proportional to the increasing speed ΔFdR stored in the storage device 63. Furthermore, the execution device 62 may set an upper limit value on the rate of increase in the driving force command value FdR while the driving force increase control is being performed.

- The execution device 62 is configured to determine that the trailing wheels have climbed over the step 101 when it is confirmed that the rate of decrease in the vehicle body speed VS becomes equal to or higher than the determined rate of decrease, and then it is confirmed that the vehicle body speed VS starts to increase. It's okay. The fact that the vehicle speed VS has started to increase may be confirmed, for example, by detecting that a predetermined period of time has continued since the vehicle speed VS started to increase from a decreasing state. Strictly speaking, the state in which the vehicle speed VS is decreasing is a state in which a load is applied to the vehicle 10 for the trailing wheels to overcome the bump 101, and the trailing wheels are located on the bump 101, and the trailing wheels are located on the bump 101. You may not have completely overcome it. Therefore, by checking the increase in the vehicle speed VS, it is possible to reliably detect the state in which the trailing wheels have climbed over the step 101.

- After starting the driving force increase control, the execution device 62 does not need to adjust the braking force instruction value FbR for suppressing the deviation of the vehicle body speed VS from the target vehicle body speed VSTr.

- The execution device 62 may continue to implement the driving force increase control until it determines that the trailing wheels have climbed over the step 101.
- When the leading wheels get over the step 101, the execution device 62 switches the control from constant speed control to driving force increase control after it becomes possible to determine that the vehicle speed VS is equal to the target vehicle speed VSTr by constant speed control. It's okay. That is, the execution device 62 may start the driving force increase control at an intermediate timing between timing t13 and timing t14 in the timing chart shown in FIG. 5, or at a timing near the intermediate timing.

- The execution device 62 may switch the control from constant speed control to driving force increase control after the trailing wheels contact the step 101, that is, after the trailing wheels reach the disturbance area. Even in this case, the driving force Fd of the vehicle 10 reaches a level that allows the trailing wheels to overcome the bump 101, compared to the case where constant speed control is continued even if the trailing wheels come into contact with the bump 101. can be increased early.

- The above-described support function for automatically driving the vehicle 10 at low speed may be realized even when the vehicle 10 is not parked.
- When the vehicle 10 is equipped with an imaging device capable of capturing an image of the road surface on which the vehicle 10 is traveling, the driving support device 60 analyzes the image captured by the imaging device to create a step 101 on the traveling route of the vehicle 10. It is possible to determine whether or not there are any disturbances such as The disturbance portion may be a depression in the running road surface or a portion where the road surface gradient changes suddenly. The execution device 62 of the driving support device 60 may start the constant speed control described above upon detecting the presence of a disturbance by analyzing an image.

- The processing circuit 61 of the driving support device 60 is not limited to one that includes a CPU and a ROM and executes software processing. That is, the processing circuit 61 may have any of the following configurations (a) to (c).

(a) The processing circuit 61 includes one or more processors that execute various processes according to computer programs. The processor includes a CPU and memory such as RAM and ROM. The memory stores program codes or instructions configured to cause the CPU to perform processes. Memory, or computer-readable media, includes any available media that can be accessed by a general purpose or special purpose computer.

(b) The processing circuit 61 includes one or more dedicated hardware circuits that execute various processes. Dedicated hardware circuits may include, for example, application specific integrated circuits, ie ASICs or FPGAs. Note that ASIC is an abbreviation for "Application Specific Integrated Circuit," and FPGA is an abbreviation for "Field Programmable Gate Array."

(c) The processing circuit 61 includes a processor that executes some of the various processes according to a computer program, and a dedicated hardware circuit that executes the remaining processes of the various processes.

Note that the expression "at least one" used in this specification means "one or more" of the desired options. As an example, the expression "at least one" as used herein means "only one option" or "both of the two options" if the number of options is two. As another example, the expression "at least one" as used herein means "only one option" or "any combination of two or more options" if there are three or more options. means.

<Other technical ideas>
Technical ideas that can be understood from the above embodiments and modified examples will be described as additional notes.
(Additional Note 1) It is preferable to include a target vehicle speed setting unit that increases the target vehicle speed after the trailing wheel passes the disturbance portion.

Claims

a command unit that performs constant speed control that adjusts the driving force and braking force of the vehicle through feedback control based on the deviation between the vehicle body speed and the target vehicle body speed;
When the constant speed control is being implemented, a point in time when a leading wheel, which is a wheel located in the traveling direction of the vehicle, among the front wheels and rear wheels of the vehicle, passes through a disturbance area that is present in the travel path of the vehicle. a storage unit that stores the speed of increase in the driving force of the vehicle;
The command unit performs driving force increase control to increase the driving force of the vehicle at the increased speed stored in the storage unit after the leading wheel passes the disturbance portion.
The driving support device according to claim 1, wherein the command unit starts the driving force increase control before a trailing wheel that is not the leading wheel among the front wheels and the rear wheel reaches the disturbance portion. .
The command unit is configured to increase the increasing speed from the increasing speed stored in the storage unit when the trailing wheel has not passed the disturbance area even after a predetermined time has elapsed since the start of the driving force increase control. The driving support device according to claim 2, wherein the driving force of the vehicle is increased at a high speed.
The command unit suppresses deviation of the vehicle body speed from the target vehicle body speed by adjusting the braking force of the vehicle after starting the driving force increase control. The driving support device according to any one of the items.