Vehicle control device

Abstract

To prevent hesitation in the stop control with respect to the stopped preceding vehicle.SOLUTION: A vehicle control device according to the present disclosure, which is a vehicle control device that executes follow-up traveling control for causing a host vehicle to travel while maintaining a constant inter-vehicle distance between the host vehicle and a preceding vehicle, includes: a target acceleration plan calculation unit that, when a stopped preceding vehicle is detected ahead of the host vehicle, calculates a target acceleration having a negative acceleration that converges to zero toward a target stop position; a brake request generation unit that, when the target acceleration becomes equal to or less than a predetermined brake request cancellation threshold value, generates a brake request for braking and stopping the host vehicle; and an acceleration restricting unit that, after the target acceleration becomes equal to or less than the brake request cancellation threshold value, maintains the target acceleration to be equal to or less than the brake request cancellation threshold value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a vehicle control device.

Background Art

[0002] One of the controls in a vehicle is a follow - up driving control (ACC: Adaptive Cruise Control) that drives the host vehicle while maintaining a constant inter - vehicle distance between the host vehicle and the preceding vehicle. In ACC, it is possible to perform a stop control in which the host vehicle decelerates with respect to a stopped preceding vehicle and stops at a target position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in ACC, it is conceivable to calculate a target inter - vehicle distance based on the current inter - vehicle distance and the actual vehicle speed, calculate a target acceleration corresponding to the target inter - vehicle distance, and perform acceleration / deceleration control based on the target acceleration. In this case, when the host vehicle approaches the target stop position, the calculated acceleration may exceed a predetermined threshold value that determines the on / off of the brake, and the brake may be released. As a result, once the stopped host vehicle may restart and a phenomenon called "creeping up" where it approaches the stopped preceding vehicle may occur.

[0005] An object of the present disclosure is to provide a vehicle control device capable of suppressing creeping up in stop control for a stopped preceding vehicle.

Means for Solving the Problems

[0006] The vehicle control device according to the present disclosure is a vehicle control device that executes follow-up travel control for driving the host vehicle while maintaining a constant inter-vehicle distance between the host vehicle and the preceding vehicle. When a stopped preceding vehicle is detected in front of the host vehicle, a target acceleration calculation unit that calculates a target acceleration having a negative acceleration that converges to zero toward a target stop position, and when the target acceleration becomes equal to or less than a predetermined brake request release threshold value, a brake request generation unit that generates a brake request to apply braking to the host vehicle to stop it, and an acceleration suppression unit that maintains the target acceleration at or below the brake request release threshold value after the target acceleration has become equal to or less than the brake request release threshold value.

Advantages of the Invention

[0007] According to the vehicle control device of the present disclosure, it is possible to suppress the creeping in the stop control for the stopped preceding vehicle.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the vehicle control device according to the present disclosure will be described with reference to the drawings.

[0010] (Example of Configuration of Vehicle Control System) FIG. 1 is a block diagram showing an example of the configuration of a vehicle control system 1 according to an embodiment. The vehicle control system 1 of the embodiment is mounted on the host vehicle and performs follow-up driving control (ACC) to drive the host vehicle while maintaining a constant inter-vehicle distance between the host vehicle and the preceding vehicle. The host vehicle is, for example, an automobile having an engine or a drive motor (not shown) as a drive source, and is accelerated by the output of the drive source and decelerated by the braking force of a brake such as a friction brake, and acceleration and deceleration (acceleration and deceleration) are performed by ACC.

[0011] As shown in FIG. 1, the vehicle control system 1 of the embodiment includes an SCM-ECU (Electronic Control Unit) 10, a front camera 20, and a VSC (VSC: Vehicle Stability Control)-30.

[0012] The front camera 20 is, for example, a stereo camera or the like, and is configured to be able to capture an image of the front of the vehicle. The stereo camera continuously captures still images at a predetermined frame rate and detects the distance to the position of the target in the captured image based on parallax information. The front camera 20 is installed, for example, at the center of the front part of the vehicle interior, on the front glass surface on the back side of the rearview mirror, so as to be able to image the front of the vehicle at a wide angle.

[0013] However, the mechanism for monitoring the front of the vehicle is not limited to a stereo camera, and for example, sensors other than a camera such as a millimeter wave sensor, a lidar, and a sonar may be used.

[0014] The SCM-ECU 10 is configured as a computer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown).

[0015] The CPU included in the SCM-ECU 10 expands and executes a control program stored in, for example, a ROM or the like in the RAM, thereby realizing, as functional units of the SCM-ECU 10, a target inter-vehicle distance planning calculation unit 11, a target acceleration planning calculation unit 12, an operation determination inter-vehicle distance calculation unit 13, a fixed acceleration request generation unit 14, a predicted stop position calculation unit 15, a brake request generation unit 16, and a storage unit 17.

[0016] The target inter-vehicle distance planning calculation unit 11 calculates a target inter-vehicle distance plan that determines a target value of the inter-vehicle distance between the host vehicle and the preceding vehicle. The target inter-vehicle distance plan is determined based on the actual inter-vehicle distance between the host vehicle and the preceding vehicle and the vehicle speed of the host vehicle so as to obtain an appropriate inter-vehicle distance.

[0017] Information on the vehicle speed and acceleration of the host vehicle can be obtained from various sensors (not shown) provided in the host vehicle. The actual inter-vehicle distance between the host vehicle and the preceding vehicle can be calculated by analyzing the image of the front camera 20. The vehicle speed and acceleration of the preceding vehicle can be estimated from the image of the front camera 20 and the information on the vehicle speed and acceleration of the host vehicle.

[0018] In addition, when there is a stopped preceding vehicle, the target inter-vehicle distance planning calculation unit 11 calculates a target inter-vehicle distance plan so that the host vehicle can stop at the target stop position in front of the stopped preceding vehicle. In this case, the target inter-vehicle distance plan is determined such that the target inter-vehicle distance gradually decreases and finally becomes equal to the distance to the target stop position.

[0019] The presence or absence of a stopped preceding vehicle can be detected, for example, by analyzing the image of the front camera 20. The target stop position is determined in advance so that the host vehicle can stop while maintaining a predetermined inter-vehicle distance from the stopped preceding vehicle.

[0020] The target acceleration planning calculation unit 12 calculates a target acceleration plan that determines a target value of the acceleration of the host vehicle so that the inter-vehicle distance between the host vehicle and the preceding vehicle becomes the target inter-vehicle distance. The target acceleration plan is determined based on the target inter-vehicle distance plan from the actual vehicle speed and acceleration of the host vehicle and the estimated vehicle speed and acceleration of the preceding vehicle.

[0021] Further, when there is a stopped leading vehicle, the target acceleration plan calculation unit 12 calculates a target acceleration plan so as to converge to the distance of the target stop position along the above-described target inter-vehicle distance plan. The target acceleration plan in this case is calculated from the current inter-vehicle distance between the host vehicle and the leading vehicle, and the current vehicle speed and acceleration of the host vehicle.

[0022] The target acceleration plan calculation unit 12 outputs the target acceleration plan calculated to make the host vehicle travel while maintaining a constant inter-vehicle distance between the host vehicle and the leading vehicle, or the target speed plan calculated to stop the host vehicle under ACC application when there is a stopped leading vehicle, to the VSC-ECU 30.

[0023] In the SCM-ECU 10 of the embodiment, in the control to stop the host vehicle under ACC application when there is a stopped leading vehicle, as will be described in detail later, the control according to the target acceleration plan is switched to the control to make the vehicle acceleration constant at a predetermined timing. For this reason, a fixed acceleration is set in the SCM-ECU 10 as the acceleration value when making the acceleration constant.

[0024] The operation determination inter-vehicle distance calculation unit 13 calculates the inter-vehicle distance assumed when the switching to the fixed acceleration is performed at a predetermined timing in the control to stop the host vehicle under ACC application. The assumed inter-vehicle distance is calculated from the predicted distance that the host vehicle advances at the fixed acceleration from the actual vehicle speed and acceleration of the host vehicle at a predetermined timing, and the actual inter-vehicle distance between the host vehicle and the stopped leading vehicle at a predetermined timing.

[0025] The assumed value of the inter-vehicle distance calculated as described above is called the operation determination inter-vehicle distance.

[0026] The fixed acceleration requirement generation unit 14 as the acceleration suppression unit generates a fixed acceleration requirement at a predetermined timing based on the operation determination inter-vehicle distance and the actual inter-vehicle distance between the host vehicle and the preceding stopped vehicle. The fixed acceleration requirement includes an instruction to switch from control according to the target acceleration plan to control by the fixed acceleration in the control for stopping the host vehicle under ACC application.

[0027] Further, after switching to control by the fixed acceleration, the fixed acceleration requirement generation unit 14 monitors the deviation amount between the predicted stop position calculated by the predicted stop position calculation unit 15 described below and the above-mentioned target stop position determined in advance. When the deviation amount between the predicted stop position and the target stop position exceeds a predetermined distance, the fixed acceleration requirement generation unit 14 generates a fixed acceleration adjustment requirement for adjusting the preset fixed acceleration. The adjustment value of the fixed acceleration is determined so that the deviation amount between the predicted stop position and the target stop position becomes equal to or less than the predetermined distance.

[0028] The fixed acceleration requirement generation unit 14 outputs to the VSC-ECU 30 the fixed acceleration requirement calculated based on the operation determination inter-vehicle distance and the actual inter-vehicle distance between the host vehicle and the preceding stopped vehicle, or the fixed acceleration adjustment requirement calculated so that the deviation amount between the predicted stop position and the target stop position becomes the predetermined distance.

[0029] The predicted stop position calculation unit 15 predicts the stop position of the host vehicle after switching to control by the fixed acceleration. The predicted stop position is calculated from the distance that the host vehicle has actually traveled under the control by the fixed acceleration, the actual inter-vehicle distance between the host vehicle and the preceding stopped vehicle, and the like. The distance that the host vehicle has actually traveled can be calculated based on the information of various sensors provided in the host vehicle.

[0030] The brake requirement generation unit 16 generates a brake requirement when the target acceleration drops below a predetermined brake requirement release threshold value in the control for stopping the host vehicle under ACC application.

[0031] The braking request includes a command to apply braking to the host vehicle to bring it to a stop. The braking request release threshold is a threshold that serves as a criterion for generating or releasing a braking request. While the target acceleration exceeds the braking request release threshold, no braking request is generated. When the target acceleration becomes equal to or lower than the braking request release threshold, a braking request is generated and braking is applied to the host vehicle.

[0032] The storage unit 17 stores a control program, control parameters, etc. for realizing the functions of the SCM-ECU 10. Further, the storage unit 17 stores information such as a target stop position, a fixed acceleration, and an upper limit value of the deviation amount between the predicted stop position and the target stop position, which are used for the control to stop the host vehicle under ACC application.

[0033] The VSC-ECU 30 is configured as a computer including, for example, a CPU, a ROM, and a RAM (not shown), and controls the brakes of the vehicle by a hydraulic system or the like to decelerate the vehicle. The hydraulic system includes a hydraulic fluid tank, a pump, a piston, a cylinder, a valve, etc., and generates power by hydraulic pressure.

[0034] When the target acceleration plan is output from the target acceleration plan calculation unit 12, the VSC-ECU 30 adjusts the deceleration of the host vehicle according to the target acceleration plan. Further, when the fixed acceleration request is output from the fixed acceleration request generation unit 16, the VSC-ECU 30 adjusts the deceleration of the host vehicle according to the fixed acceleration request instead of the target acceleration plan. Further, when a new fixed acceleration adjustment request is output from the fixed acceleration request generation unit 16, the VSC-ECU 30 adjusts the deceleration of the host vehicle according to the fixed acceleration adjustment request.

[0035] Further, when the braking request is output from the braking request generation unit 16, the VSC-ECU 30 controls the brakes to apply braking to the host vehicle to bring it to a stop.

[0036] (Control Example of Vehicle Control System) Next, with reference to FIGS. 2 and 3, control for stopping the host vehicle 100 at the target stop position with respect to the stopped preceding vehicle 200 by the vehicle control system 1 of the embodiment will be described. FIG. 2 is a schematic diagram showing an example of control by the vehicle control system 1 according to the embodiment.

[0037] As shown in FIG. 2(a), when a stopped preceding vehicle 200 is detected in front of the host vehicle 100 from the image of the front camera 20, the target inter-vehicle distance planning calculation unit 11 of the SCM-ECU 10 calculates a target inter-vehicle distance plan so that the host vehicle 100 can stop at the target stop position in front of the stopped preceding vehicle 200.

[0038] Further, the target acceleration plan calculation unit 12 calculates a target acceleration plan so as to follow the target inter-vehicle distance plan calculated by the target inter-vehicle distance planning calculation unit 11 and outputs it to the VSC-ECU 30. The VSC-ECU 30 starts decelerating the host vehicle 100 according to the target acceleration plan output from the target inter-vehicle distance planning calculation unit 11.

[0039] When the target acceleration drops below a predetermined brake request release threshold, the brake request generation unit 16 generates a brake request and outputs it to the VSC-ECU 30. The VSC-ECU 30 controls the brakes according to the brake request output from the brake request generation unit 16 to apply braking to the host vehicle 100.

[0040] On the other hand, when control for stopping the host vehicle 100 at the target stop position with respect to the stopped preceding vehicle 200 is started, the operation determination inter-vehicle distance calculation unit 13 calculates an operation determination inter-vehicle distance based on the actual inter-vehicle distance between the host vehicle 100 and the stopped vehicle 200 at each timing.

[0041] The fixed acceleration request generation unit 14 generates a fixed acceleration request when the operation determination inter-vehicle distance matches the actual inter-vehicle distance between the host vehicle and the stopped preceding vehicle at a predetermined timing and outputs it to the VSC-ECU 30. The VSC-ECU 30 continues to decelerate the host vehicle 100 according to the fixed acceleration request output from the fixed acceleration request generation unit 14 instead of the target acceleration plan output from the target inter-vehicle distance planning calculation unit 11.

[0042] When the fixed acceleration requirement is output to the VSC-ECU 30 and the VSC-ECU 30 starts decelerating the host vehicle 100 in accordance with the fixed acceleration requirement, the predicted stop position calculation unit 15 calculates the predicted stop position at each timing. When the deviation amount between the predicted stop position calculated by the predicted stop position calculation unit 15 and the target stop position exceeds a predetermined value, the fixed acceleration generation unit 14 generates a fixed acceleration adjustment requirement adjusted so that the deviation amount between the predicted stop position and the target stop position becomes equal to or less than a predetermined distance, and outputs it to the VSC-ECU 30. When the fixed acceleration adjustment requirement is generated from the target inter-vehicle distance planning calculation unit 11, the VSC-ECU 30 continues to decelerate the host vehicle 100 in accordance with the fixed acceleration adjustment requirement newly output from the fixed acceleration generation unit 14 instead of the initial fixed acceleration requirement.

[0043] As shown in FIG. 2(b), as a result of the above control by the vehicle control system 1, the host vehicle 100 can be stopped within a predetermined error range from the target stop position.

[0044] Details of the behavior of the host vehicle 100 in the stop control shown in FIG. 2 are shown in FIG. 3 together with the behavior of the vehicle control system of the comparative example.

[0045] FIG. 3 is a graph showing the behavior of the host vehicle during stop control in the vehicle control systems according to the embodiment and the comparative example. The graphs in FIGS. 3(a) and 3(b) respectively show the inter-vehicle distance between the host vehicle and the preceding stopped vehicle and the acceleration of the host vehicle during stop control by the vehicle control system 1 of the embodiment. The graphs in FIGS. 3(c) and 3(d) respectively show the acceleration of the host vehicle during stop control by the vehicle control system of the comparative example and the generation and cancellation of the brake requirement.

[0046] The horizontal axis in FIGS. 3(a) to 3(d) is time in all cases. The vertical axis in FIG. 3(a) is the inter-vehicle distance, the vertical axes in FIGS. 3(b) and 3(c) are acceleration, and FIG. 3(d) shows the on / off state of the brake requirement.

[0047] As shown in FIG. 3(c), in the vehicle control system of the comparative example, control is completed according to the target acceleration plan until the host vehicle stops at the target stop position.

[0048] In the target acceleration plan for stop control, a negative acceleration is set to decelerate the host vehicle. Also, in order to improve the drivability of the host vehicle, the negative acceleration applied to the host vehicle is determined to gradually decrease initially, reach a peak value at a predetermined timing, and then gradually increase. That is, at the beginning of the stop control, the host vehicle gradually increases the deceleration, and after reaching the peak value, the deceleration gradually weakens toward the target stop position.

[0049] Such control also matches the target inter-vehicle distance plan that smoothly converges toward the target stop position. That is, near the target stop position, the difference between the target inter-vehicle distance determined by the target inter-vehicle distance plan and the inter-vehicle distance from the stopped vehicle at the target stop position converges to zero, and accordingly, the target acceleration determined by the target acceleration plan also converges to zero.

[0050] For the target acceleration determined in this way, a brake request release threshold value is set in advance. When the target acceleration that is the target acceleration according to the target acceleration plan and takes a negative value to decelerate the host vehicle gradually decreases, at a predetermined timing, the negative target acceleration becomes less than or equal to the brake request release threshold value. On the other hand, after reaching the peak value, the negative target acceleration turns to increase and exceeds the brake request release threshold value at a predetermined timing.

[0051] As shown in FIG. 3(d), the brake request generation unit of the comparative example generates a brake request at the timing when the initially gradually decreasing negative target acceleration becomes less than or equal to the brake request release threshold value and outputs it to the VSC-ECU. Also, the brake request generation unit of the comparative example releases the brake request when the negative target acceleration that has turned to increase after reaching the peak value exceeds the brake request release threshold value.

[0052] As a result, when the host vehicle reaches the target stop position and the vehicle speed becomes 0 km / h, the brakes of the host vehicle are released, and a phenomenon called "creeping" occurs where the host vehicle starts moving forward again. Due to the occurrence of creeping, the host vehicle may approach the preceding stopped vehicle too closely and may not be able to stop at the target stop position.

[0053] As shown in FIG. 3(a), in the vehicle control system 1 of the embodiment, the above-described target inter-vehicle distance planning unit 11 calculates a target inter-vehicle distance plan such that the target inter-vehicle distance smoothly converges toward the target stop position. Further, the operation determination inter-vehicle distance calculation unit 13 provided in the SCM-ECU 10 of the embodiment calculates an operation determination inter-vehicle distance that is assumed when a fixed acceleration is applied at each timing.

[0054] Initially, when the negative acceleration is close to zero according to the target acceleration plan, the set value of the acceleration is higher than the fixed acceleration, and the operation determination inter-vehicle distance assumed when the fixed acceleration is applied is calculated to be shorter than the target inter-vehicle distance determined by the target inter-vehicle distance plan. As the negative acceleration decreases according to the target acceleration plan, the set value of the acceleration becomes lower than the fixed acceleration, and at the timing near when the negative acceleration passes the peak value, the operation determination inter-vehicle distance and the target inter-vehicle distance coincide.

[0055] The timing at which the operation determination inter-vehicle distance and the target inter-vehicle distance coincide is, hereafter, the timing at which it is possible to stop the host vehicle at the target stop position by performing control with the fixed acceleration.

[0056] As shown in FIG. 3(b), the fixed acceleration request generation unit 14 generates a fixed acceleration request at the timing when the operation determination inter-vehicle distance and the target inter-vehicle distance coincide and outputs it to the VSC-ECU 30. In this way, the operation determination inter-vehicle distance is used to determine the timing of operating the control of the host vehicle with the fixed acceleration. Also, the timing at which the operation determination inter-vehicle distance and the target inter-vehicle distance coincide is also referred to as the operation timing of operating the control of the host vehicle with the fixed acceleration.

[0057] Also, after the timing when the operation determination inter-vehicle distance and the target inter-vehicle distance match, the host vehicle is controlled at a constant acceleration using a fixed acceleration regardless of the target acceleration plan. Therefore, it is possible to suppress the occurrence of a creep where the target acceleration exceeds the brake release threshold and the brake is released near the target stop position. Since the brake request is always on until the vehicle speed of the host vehicle becomes 0 km / h near the target stop position, the host vehicle can be transitioned to a stop hold state and stopped more reliably.

[0058] The predicted stop position calculation unit 15 calculates the predicted stop position for the host vehicle under control by a fixed acceleration. The control of the host vehicle by a fixed acceleration is started after determining the timing at which the host vehicle can be stopped at the target stop position at a fixed acceleration as described above. However, the actual stop position can vary due to various disturbances.

[0059] Therefore, after starting the control by a fixed acceleration, the fixed acceleration request generation unit 14 monitors the deviation amount between the predicted stop position calculated by the predicted stop position calculation unit 15 and the target position. When the deviation amount exceeds a predetermined value, it generates a fixed acceleration adjustment request to adjust the fixed acceleration and outputs it to the VSC-ECU 30.

[0060] Disturbance factors that affect the stop position include, for example, road surface conditions and weather conditions such as wind. Also, since there is a limit to the resolution of the front camera 20, an error can occur in the relative distance from the stop leading vehicle analyzed from the image of the front camera 20. Such an error caused by the resolution of the front camera 20 also becomes a disturbance factor for the variation of the stop position.

[0061] In this way, by monitoring the deviation amount between the predicted stop position and the target position of the host vehicle under control by a fixed acceleration and adjusting the fixed acceleration as necessary, the host vehicle can be stopped within a predetermined error range from the target stop position.

[0062] (Processing example of vehicle control device) Next, with reference to FIG. 4, a processing example of the stop control of the host vehicle by the SCM-ECU 10 of the embodiment will be described. FIG. 4 is a flowchart showing an example of the procedure for the stop control of the host vehicle under ACC application by the SCM-ECU 10 according to the embodiment.

[0063] As shown in FIG. 4, for example, when a stopped preceding vehicle is detected in front of the host vehicle by image analysis of the front camera 20 or the like (step S101), the target inter-vehicle distance planning calculation unit 11 generates a target inter-vehicle distance plan in which the target inter-vehicle distance converges toward the target stop position (step S102). Further, the target acceleration plan calculation unit 12 generates a target acceleration plan in which the target acceleration converges toward the target stop position according to the calculated target inter-vehicle distance plan, and outputs it to the VSC-ECU 30 (step S103).

[0064] Thereafter, the brake request generation unit 16 starts monitoring the target acceleration. While the target acceleration is higher than the brake request release threshold, the brake request generation unit 16 does not generate a brake request. When the target acceleration becomes equal to or lower than the brake request release threshold, the brake request generation unit 16 generates a brake request and outputs it to the VSC-ECU 30.

[0065] The operation determination inter-vehicle distance calculation unit 13 calculates an inter-vehicle distance that may occur between the host vehicle and the stopped preceding vehicle when a fixed acceleration is applied, and calculates an operation determination inter-vehicle distance for determining the operation timing of the fixed acceleration (step S104). The fixed acceleration request generation unit 14 monitors the timing at which the calculated operation determination inter-vehicle distance and the target inter-vehicle distance defined in the target inter-vehicle distance plan match (step S105). The fixed acceleration request generation unit 14 continues these monitorings while the operation determination inter-vehicle distance and the target inter-vehicle distance do not match (step S105: No).

[0066] When the operating determination inter-vehicle distance matches the target inter-vehicle distance (step S105: Yes), the fixed acceleration request generation unit 14 generates a fixed acceleration request and outputs it to the VSC-ECU 30 (step S106). Also, thereafter, the predicted stop position calculation unit 15 appropriately calculates the predicted stop position of the host vehicle under control with the fixed acceleration (step S107).

[0067] The fixed acceleration request generation unit 14 monitors whether the deviation amount between the predicted stop position calculated from time to time and the target stop position exceeds a predetermined threshold (step S108). When the deviation amount between the predicted stop position and the target stop position exceeds the predetermined threshold (step S108: Yes), the fixed acceleration request generation unit 14 generates a fixed acceleration adjustment request and outputs it to the VSC-ECU 30 (step S109). If the deviation amount between the predicted stop position and the target stop position remains below the predetermined threshold (step S108: No), the fixed acceleration request generation unit 14 does not perform the process of step S109.

[0068] Also, while the control of the host vehicle based on the fixed acceleration request or the fixed acceleration adjustment request continues, the SCM-ECU 10 appropriately monitors whether the host vehicle has stopped (step S110). While the host vehicle has not stopped (step S110: No), the SCM-ECU 10 repeats the processes after step S107 and continues to adjust the fixed acceleration as necessary. When the host vehicle stops (step S110: Yes), the SCM-ECU 10 ends the process.

[0069] Thus, the process of the stop control of the host vehicle by the SCM-ECU 10 of the embodiment ends.

[0070] (Summary) In the stop control of the host vehicle under ACC application, when the target acceleration becomes equal to or less than the brake request release threshold value, a brake request is output to the VSC-ECU, and braking is applied to the host vehicle. However, since the target acceleration converges to zero near the target stop position, the brake request release threshold value may be exceeded, and the brake request may be released. As a result, a creeping phenomenon occurs in which the host vehicle approaches and gets close to the stopped preceding vehicle. This makes it difficult to stop at the target stop position and also degrades drivability.

[0071] According to the SCM-ECU 10 of the embodiment, when a stopped preceding vehicle is detected in front of the host vehicle, after the target acceleration becomes equal to or less than the brake request release threshold value, a fixed acceleration request generation unit 14 that maintains the target acceleration equal to or less than the brake request release threshold value is provided. Thereby, it is possible to suppress the release of the brake request near the target stop position and suppress the creeping phenomenon in the stop control with respect to the stopped preceding vehicle.

[0072] According to the SCM-ECU 10 of the embodiment, the fixed acceleration request generation unit 14 switches the control of the host vehicle from the target acceleration to the control according to the fixed acceleration at the timing when the target inter-vehicle distance and the operating inter-vehicle distance match. In this way, after determining the operation timing based on the operating inter-vehicle distance and operating the control of the host vehicle with the fixed acceleration, the host vehicle can be stopped at a position closer to the target stop position more reliably.

[0073] According to the SCM-ECU 10 of the embodiment, when the difference between the predicted stop position and the target stop position exceeds a predetermined threshold value, the fixed acceleration request generation unit 14 adjusts the value of the fixed acceleration so that the difference between the predicted stop position and the target stop position becomes equal to or less than the predetermined threshold value. Thereby, it is possible to reduce the error of the stop position due to disturbance and improve the stop position accuracy of the host vehicle with respect to the target stop position.

Description of Reference Numerals

[0074] 1 Vehicle control system 10 SCM-ECU 11 Target inter-vehicle distance planning calculation unit 12 Target acceleration calculation unit 13 Inter-vehicle distance calculation unit for operation determination 14 Fixed acceleration requirement generation unit 15 Predicted stop position calculation unit 16 Brake requirement generation unit 17 Memory unit 20 Front camera 30 VSC-ECU 100 Own vehicle 200 Stopping leading vehicle

Claims

1. A vehicle control device that executes a follow-up driving control for driving the host vehicle while maintaining a constant inter-vehicle distance between the host vehicle and a preceding vehicle, when a stopped preceding vehicle is detected in front of the host vehicle, a target acceleration calculation unit that calculates a target acceleration having a negative acceleration that converges to zero toward a target stop position; a brake request generation unit that generates a brake request to apply braking to the host vehicle to stop when the target acceleration becomes equal to or less than a predetermined brake request release threshold; and an acceleration suppression unit that maintains the target acceleration equal to or less than the brake request release threshold after the target acceleration becomes equal to or less than the brake request release threshold. A vehicle control device.

2. when a stopped preceding vehicle is detected in front of the host vehicle, a target inter-vehicle distance calculation unit that calculates a target inter-vehicle distance that converges toward the target stop position; and an operating inter-vehicle distance calculation unit that calculates, as an operating inter-vehicle distance, an inter-vehicle distance that can occur between the host vehicle and the stopped preceding vehicle when a fixed acceleration having a predetermined constant value is applied to the host vehicle. The vehicle control device according to claim 1, further comprising: wherein the acceleration suppression unit switches the control of the host vehicle to control according to the fixed acceleration from the target acceleration at a timing when the target inter-vehicle distance and the operating inter-vehicle distance match.

3. further comprising a predicted stop position calculation unit that calculates a predicted stop position of the host vehicle under control according to the fixed acceleration, wherein the acceleration suppression unit adjusts the value of the fixed acceleration so that the difference between the predicted stop position and the target stop position becomes equal to or less than a predetermined threshold when the difference between the predicted stop position and the target stop position exceeds the predetermined threshold. The vehicle control device according to claim 2. ​

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