Vehicle driving control device

Abstract

The present invention provides a vehicle driving control device, which prevents the driver from accidentally accelerating when the automatic driving mode is changed to the manual driving mode after the automatic driving mode has lasted for a long time, even if the driver mistakenly performs excessive acceleration operation due to the reduced feeling of the acceleration operation. In the automatic driving mode, the slope of the characteristic of the acceleration-acceleration characteristic table showing the relationship between the acceleration opening θac and the target acceleration αt is set smaller than the normal characteristic according to the duration Tau of the automatic driving mode (S13). Then, when the driving mode is changed to the manual driving mode, the characteristic set in the acceleration-acceleration characteristic table is referred to, and the target acceleration αt is set based on the acceleration opening θac detected by the acceleration opening sensor (34).

Description

Technical Field

[0001] The present invention relates to a vehicle travel control device that suppresses acceleration until the driver's sense of acceleration operation is restored when a driving mode is changed from an automatic driving mode to a manual driving mode. Background Art

[0002] In recent vehicles, various driving assistance technologies have been proposed to reduce the burden on the driver and enable comfortable and safe driving, and some of them have been put into practical use. In this type of driving assistance, when the automatic driving mode is selected as the driving mode, if the driver sets a driving route to the destination, the target travel path that the vehicle should travel along the driving route is set to a predetermined distance ahead, and the vehicle is driven autonomously along the target travel path (navigation-linked route driving). At this time, the front, back, left, and right sides of the vehicle's position are always monitored through the well-known following distance control (ACC: Adaptive Cruise Control) and lane keeping control (ALK: Active Lane Keep).

[0003] When the vehicle is driving in the automatic driving mode, the driver basically does not perform acceleration, steering, or braking operations. However, when the conditions for automatic driving are not met, or the road is a manual driving zone, or the driver consciously performs steering and / or braking operations and the control unit determines that the automatic driving mode is invalid, the driving mode will be changed from the automatic driving mode to the manual driving mode, and the driver will take over the driving operation.

[0004] During driving in automatic driving mode, the driver is in a careless state. Therefore, even if the driving operation is suddenly taken over from such a state, it is difficult to immediately restore the driver's feeling for the acceleration operation, and there is a situation where it is difficult to smoothly take over the driving mode to the manual driving mode.

[0005] Therefore, for example, in patent document 1 (Japanese Patent Gazette No. 2019-93924), the following technology is disclosed: when the driving mode is changed from the automatic driving mode to the manual driving mode, the driving force of the vehicle is controlled to be slowly transferred from the driving force in the automatic driving mode to the driving force required by the driver in the manual driving mode at a ratio that does not cause the occupants to feel vibration, thereby smoothly completing the change of the driving mode.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-93924 Summary of the invention

[0009] Technical issues

[0010] However, since the driver basically does not perform acceleration operations during driving in the automatic driving mode, when the driving mode is changed from the automatic driving mode to the manual driving mode, the driver's feeling of the acceleration operation gradually decreases as the driving time in the automatic driving mode increases.

[0011] However, in the technology disclosed in the above-mentioned document, the driving force is transferred regardless of the elapsed time of driving in the automatic driving mode. Therefore, for example, when the automatic driving mode is switched to the manual driving mode in a short period of time after the start of the automatic driving mode, the driver's feeling of the acceleration operation has not yet decreased. In this way, when the control of the driving force transfer disclosed in the above-mentioned document is performed, the responsiveness is poor, which may cause discomfort to the driver.

[0012] On the other hand, when the driving in the automatic driving mode continues for a long time and then changes to the manual driving mode, the driver's operating feeling of the accelerator pedal is significantly reduced, so there is a possibility of excessive depression of the accelerator pedal. In the above-mentioned document, when the depression amount of the accelerator pedal is more than a predetermined amount, it is determined that this is the driving force required by the driver, and the control unit performs control such that the driving force is transferred to the required driving force. Therefore, there is a disadvantage that the driver's unintentional sudden acceleration occurs, which makes the driver feel uncomfortable.

[0013] In view of the above situation, the present invention aims to provide a vehicle driving control device, so that when the driving mode is changed from the automatic driving mode to the manual driving mode, even if the automatic driving mode is changed to the manual driving mode within a short time after the start of the automatic driving mode, a driving force corresponding to the driver's acceleration operation can be generated without causing discomfort to the driver. In addition, in a case where the automatic driving mode is changed to the manual driving mode after lasting for a long time, even if the driver mistakenly performs excessive acceleration operation due to a decrease in the driver's feeling for the acceleration operation, sudden acceleration unintentionally by the driver will not occur, and the driver will not feel uncomfortable.

[0014] Technical Solution

[0015] The present invention provides a vehicle driving control device including an acceleration operation amount detection unit for detecting an acceleration operation amount of a driver, and a driving mode determination unit for determining whether the current driving mode is the automatic driving mode or the manual driving mode based on driving conditions, and including an automatic driving duration calculation unit for calculating the duration of the automatic driving mode when the driving mode determination unit determines that the driving mode is the automatic driving mode; an acceleration characteristic setting unit for variably setting a characteristic of a target acceleration with respect to the acceleration operation amount detected by the acceleration operation amount detection unit based on the duration calculated by the automatic driving duration calculation unit; and a target acceleration setting unit for setting the target acceleration corresponding to the acceleration operation amount detected by the acceleration operation amount detection unit with reference to the characteristic of the target acceleration with respect to the acceleration operation amount set by the acceleration characteristic setting unit when the driving mode determination unit determines that the driving mode is changed from the automatic driving mode to the manual driving mode.

[0016] Technical Effects

[0017] According to the present invention, when the driving mode is determined to be the automatic driving mode, the duration of the automatic driving mode is calculated, and the characteristics of the target acceleration relative to the acceleration operation amount are variably set based on the duration. Thereafter, when the driving mode is determined to be changed from the automatic driving mode to the manual driving mode, the target acceleration corresponding to the acceleration operation amount is set with reference to the characteristics of the target acceleration relative to the acceleration operation amount. Therefore, when the driving mode is changed from the automatic driving mode to the manual driving mode, in the case where the duration of the automatic driving mode so far is short, a driving force corresponding to the driver's acceleration operation can be generated without causing discomfort to the driver.

[0018] In addition, when the automatic driving mode is switched to the manual driving mode after being continued for a long time, the target acceleration can be suppressed. Therefore, even if the driver mistakenly performs excessive acceleration due to a decrease in the driver's feeling for the acceleration operation, unintentional sudden acceleration will not occur, and the driver will not feel uncomfortable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram of the overall structure of the travel control device.

[0020] Figure 2 is a flowchart showing an acceleration suppression control routine.

[0021] Figure 3is a flowchart showing the acceleration-acceleration characteristic updating subroutine.

[0022] Figure 4 is a flowchart showing the acceleration operation speed threshold value update subroutine.

[0023] Figure 5 : is a flowchart showing the acceleration suppression control subroutine at the time of transition to manual driving.

[0024] Figure 6 is a conceptual diagram showing an acceleration-acceleration characteristic table.

[0025] Figure 7 : is a conceptual diagram showing an acceleration suppression amount setting map.

[0026] Figure 8 : is a conceptual diagram showing an accelerator operation speed threshold value setting map.

[0027] Explanation of symbols

[0028] 1: Driving control device

[0029] 11: Driving control unit

[0030] 21: Camera unit

[0031] 21a: Main Camera

[0032] 21b: Secondary camera

[0033] 21c: IPU (Image Processing Unit)

[0034] 21d: Driving environment information recognition unit

[0035] 22: Navigation System

[0036] 31: Autopilot switch

[0037] 32: Steering wheel angle sensor

[0038] 33: Vehicle speed sensor

[0039] 34: Acceleration opening sensor

[0040] 35: Brake switch

[0041] 41: EPS drive unit

[0042] 42: Acceleration and deceleration drive unit

[0043] 43: Brake drive unit

[0044] 44: Notification device

[0045] Hi: Upper limit

[0046] Lo: Lower limit

[0047] M: This vehicle

[0048] Tao: Continuous determination threshold

[0049] Tau: Duration of autonomous driving

[0050] Tma: elapsed time

[0051] Tmo: Initial suppression judgment time

[0052] V: Vehicle speed

[0053] Vo: Low speed judgment threshold

[0054] αt: target acceleration

[0055] θac: Acceleration opening

[0056] θso: Straight road judgment threshold

[0057] θst: steering wheel angle

[0058] ωac: Acceleration operation speed

[0059] ωs1: Acceleration operation speed threshold DETAILED DESCRIPTION

[0060] Hereinafter, one embodiment of the present invention will be described based on the drawings. Figure 1 The driving control device 1 shown is mounted on the vehicle M. The driving control device 1 includes a driving control unit 11 that sets the driving mode of the vehicle M according to driving conditions. The driving control unit 11 and a driving environment information recognition unit 21d of a camera unit 21 described later are mainly composed of a well-known microcomputer having a CPU, ROM, RAM, and nonvolatile memory, and the ROM stores various programs executed by the CPU, various fixed data, and the like.

[0061] The driving modes set by the driving control unit 11 include a manual driving mode in which the driver performs driving operations, an automatic driving mode in which the vehicle autonomously drives along a target new route, and an automatic avoidance mode. It should be noted that the automatic avoidance mode is a mode in which, when it is determined that the automatic driving mode is difficult to continue during driving in the automatic driving mode, the vehicle M is automatically guided to a safe place such as a shoulder of the road without switching to the manual driving mode. Here, the situation in which the automatic driving mode is difficult to continue is, for example, a situation in which a large steering wheel angle θst is detected by the steering wheel angle sensor 32 described later. Such a situation can be inferred that the driver has become unconscious or unconscious and is lying on the steering wheel.

[0062] The automatic driving mode is a driving mode that makes the vehicle M drive autonomously (automatically) along the target travel path. It should be noted that the automatic driving mode can be further divided into a steering mode that requires the driver to hold the steering wheel and a hands-off mode that does not require the driver to hold the steering wheel, but in this embodiment, these are collectively referred to as the automatic driving mode.

[0063] In addition, the target travel path set by the driving control unit 11 is linked to the driving route set by the navigation system 22 described later. In the navigation system 22, if the driver sets a destination, the current position of the vehicle M is estimated based on the positioning signal from the GNSS (Global Navigation Satellite System) satellite, and the driving route connecting the current position and the destination is formed on the road map.

[0064] The driving control unit sets a target travel path (straight road, lane change to a branch lane, etc.) along the travel route in front of the host vehicle M. Then, when the driving mode is set to the automatic driving mode, the host vehicle M is automatically driven (autonomous driving) along the target travel path. On the other hand, when the destination is not set in the navigation system 22, the driving control unit 11 sets the target travel path in a manner such that the host vehicle M travels in the center of the lane in which the host vehicle M is currently traveling through ACC control and ALK control.

[0065] In addition, a camera unit 21 and a navigation system 22 are connected to the input side of the driving control unit 11 as units for acquiring parameters required for setting the driving mode. The camera unit 21 is fixed to the center of the upper front part of the interior of the vehicle M, and includes a vehicle-mounted camera (stereo camera) composed of a main camera 21a and a sub-camera 21b arranged at left-right symmetrical positions sandwiching the center in the vehicle width direction, an image processing unit (IPU) 21c, and a driving environment information recognition unit 21d. The camera unit 21 performs predetermined image processing on the driving environment image information of the front and surrounding of the vehicle M captured by the two cameras 21a and 21b using the IPU 21c, and sends it to the driving environment information recognition unit 21d.

[0066] The driving environment information recognition unit 21d obtains the width (vehicle width) between the left and right dividing lines that divide the lane where the host vehicle M is traveling based on the received driving environment image information, calculates the center (lane center), and sets the lane center as the target travel path of the host vehicle M. Furthermore, the driving environment information recognition unit 21d recognizes the preceding vehicle traveling in front of the host vehicle M, dropped objects on the road, etc., based on the received driving environment image information using methods such as pattern matching.

[0067] On the other hand, the navigation system 22 has a high-precision road map database composed of a large-capacity storage medium such as an HDD, and the high-precision road map database stores high-precision road map information (dynamic map). The high-precision road map information (hereinafter referred to as "road map information") has lane data (lane width data, lane center position coordinate data, lane travel azimuth data, speed limit, etc.) required for automatic driving, and the lane data is stored at intervals of several meters for each lane on the road map.

[0068] The navigation system 22 receives positioning signals from GNSS satellites to obtain the position coordinates of the vehicle M, and performs map matching on the road map information to estimate the position of the vehicle M on the road map. In addition, in an environment where it is impossible to receive effective positioning signals from positioning satellites, such as when driving in a tunnel, the navigation system 22 switches to autonomous navigation and estimates the position of the vehicle M on the road map based on the vehicle speed detected by the vehicle speed sensor, the angular velocity detected by the gyro sensor, and / or the longitudinal acceleration detected by the longitudinal acceleration sensor.

[0069] Then, the vehicle position on the road map information and the road map information of its surroundings are obtained. Then, if the driver sets the destination on the road map information, the navigation system 22 calculates and sets the driving route from the vehicle position (current position) to the destination based on the road map information. It should be noted that when setting the target travel path linked to the driving route for driving the vehicle M, the information obtained by the camera unit 21 and the navigation system 22 are also read into the driving control unit 11.

[0070] Furthermore, sensors and switches for detecting the driver's spontaneous driving operation are connected to the input side of the driving control unit 11 , and a drive unit for controlling the driving of the host vehicle M in the automatic driving mode is connected to the output side.

[0071] The above-mentioned sensors / switches, specifically, include an automatic driving switch 31 as a driving mode selection unit, in which the driver selects the on / off of automatic driving through external operation; a steering wheel angle sensor 32 as a steering wheel angle detection unit, which detects the steering wheel angle θst during automatic driving or manual driving; a vehicle speed sensor 33 as a vehicle speed detection unit, which detects the vehicle speed (vehicle speed) V of the vehicle M; an accelerator opening sensor 34 as an accelerator operation amount detection unit, which detects the amount of accelerator pedal depression (operation amount); and a brake switch 35 that detects the depression of the brake pedal and performs an opening action.

[0072] In addition, the driving unit for controlling the travel of the vehicle M is composed of an EPS driving unit 41 that drives an electric power steering (EPS) motor, an acceleration / deceleration driving unit 42 that controls the output of a driving source (engine, electric motor), and a brake driving unit 43 that supplies brake fluid pressure to wheel cylinders of brake calipers provided at each wheel to forcibly actuate the brakes. Furthermore, a notification device 44 composed of an audio speaker and / or a monitor is connected to the output side of the travel control unit 11.

[0073] The driving control unit 11 performs acceleration suppression control for allowing the driver to smoothly take over the driving operation when the driving mode is changed from the automatic driving mode to the manual driving mode. In this acceleration suppression control, the acceleration-acceleration characteristic and the acceleration operation speed threshold ωsl are always updated for each calculation cycle during the execution of the automatic driving mode. Then, when the driving mode is changed to the manual driving mode, the target acceleration αt is set based on the acceleration opening θac and the acceleration-acceleration characteristic and the acceleration operation speed threshold ωsl. Here, the acceleration-acceleration characteristic is a characteristic that limits the target acceleration αt corresponding to the acceleration opening θac according to the duration in the automatic driving mode. In addition, the acceleration operation speed threshold ωsl is a value for determining the acceleration operation speed ωac described later.

[0074] The acceleration suppression control executed by the driving control unit 11 is specifically performed according to Figure 2 The acceleration suppression control routine shown is used to handle this.

[0075] In this routine, first, in step S1, it is checked whether the automatic driving control is in progress, that is, whether the current driving mode is the automatic driving mode. It should be noted that the processing in this step corresponds to the driving mode determination unit of the present invention.

[0076] Then, when the automatic driving switch 31 is turned on and the driving conditions for automatic driving (driving in the automatic driving zone, etc.) are met, the driving mode is set to the automatic driving mode. In addition, when the automatic driving switch 31 is turned off, or when the automatic driving switch 31 is turned on and it is determined to be invalid due to the driver stepping on the accelerator pedal or operating the steering wheel, the driving conditions for automatic driving are no longer met, and the mode is changed to the manual driving mode.

[0077] In addition, if it is determined that the automatic driving control is in progress, the acceleration-acceleration characteristic update process of step S2 and the acceleration operation speed threshold update process of step S3 are executed in parallel and the routine is exited. On the other hand, if it is determined that the manual driving mode is in progress, the routine is branched to step S4, and the acceleration suppression control process is executed when the vehicle is in manual driving and the routine is exited.

[0078] The processing in step S2 is as follows Figure 3The subroutine is executed by the acceleration-acceleration characteristic update subroutine shown in FIG. In this subroutine, first, in step S11, the duration from when the driving mode during driving is set to the automatic driving mode, that is, the automatic driving duration Tau is calculated. It should be noted that the processing in this step corresponds to the automatic driving duration calculation unit of the present invention.

[0079] Next, the process proceeds to step S12, where the automatic driving duration Tau is compared with a preset duration determination threshold Tao. For example, if the driver drives the vehicle in the manual driving mode before reaching the automatic driving permission zone (highway, etc.), and drives the vehicle in the automatic driving mode when reaching the automatic driving permission zone, the driver's feeling for the acceleration operation does not decrease during the predetermined driving time immediately after the transition to the automatic driving mode, and therefore, it is not necessary to limit the target acceleration αt with respect to the acceleration operation amount (accelerator opening θac).

[0080] Therefore, if Tau<Tao, the routine is exited. On the other hand, if Tau≥Tao, it is determined that the duration is long and the feeling of the acceleration operation is reduced, and the process proceeds to step S13. In this way, the continuation determination threshold Tao is a value for determining whether there is a sign that the driver's feeling of the acceleration operation is reduced. Since there are individual differences, it can be set for each driver. Alternatively, it can be set to a fixed value of about 5 to 10 [min].

[0081] Then, if the process proceeds to step S13, based on the autonomous driving duration Tau, and referring to Figure 6 The characteristic of the target acceleration αt with respect to the accelerator opening θac is set using the acceleration-acceleration characteristic table shown in FIG.

[0082] like Figure 6 As shown in FIG. 1 , the relationship between the accelerator opening θac and the target acceleration αt is almost proportional. When the straight line shown by the bold line is regarded as a normal characteristic in which the accelerator opening and the target acceleration αt correspond to each other at a ratio of 1:1, the slope of the acceleration-acceleration characteristic is gradually set to be smaller as the automatic driving duration Tau increases. It should be noted that the degree of the slope of the characteristic is set according to the degree of reduction in the driver's feeling for the acceleration operation due to the passage of time.

[0083] The target acceleration may also be obtained from a linear equation of target acceleration = K·automatic driving duration. In this case, the coefficient (slope) K is set according to the degree of time elapsed.

[0084] Then, the routine proceeds to step S14, and the acceleration-acceleration characteristic stored in the memory is updated with the acceleration-acceleration characteristic set this time, and the routine is exited. As a result, the slope of the target acceleration αt with respect to the acceleration opening θac becomes smaller (lower) as the automatic driving duration Tau becomes longer, so the limit ratio of the target acceleration αt with respect to the acceleration opening θac gradually increases. It should be noted that the slope of this characteristic becomes constant when the automatic driving duration Tau has passed a predetermined time (for example, 30 to 60 [min]).

[0085] In addition, the processing in step S3 is performed according to Figure 4 The subroutine is executed by the acceleration operation speed threshold value update subroutine shown in FIG. In this subroutine, first, in step S21, the steering wheel angle θst [deg] detected by the steering wheel angle sensor 32 and the vehicle speed V [Km / h] detected by the vehicle speed sensor 33 are read. Next, the routine proceeds to step S22, and the steering wheel angle θst is compared with the straight road determination threshold value θso. Then, if it is determined that the vehicle is traveling on a curved road with θst>θso, the routine proceeds to step S23. In addition, if it is determined that the vehicle is traveling on a nearly straight road with θst≤θso, the routine is exited.

[0086] If the process proceeds to step S23, the vehicle speed V is compared with the low speed determination threshold value Vo. If the vehicle is traveling at a medium-high speed of V>Vo, the process proceeds to step S24. If the vehicle is traveling at a low speed of V≤Vo, the routine is exited.

[0087] That is, when the vehicle M is traveling on a straight road (θst≤θso) or at a low speed (V≤Vo) in the automatic driving mode, even if the driving mode is switched to the manual driving mode, the possibility of the vehicle M deviating from the lane is low even if the accelerator pedal is stepped on relatively heavily during the driving on the straight road. On the other hand, even if the driving mode is switched to the manual driving mode during the driving at a low speed, the possibility of the driver stepping on the accelerator pedal relatively heavily is low. In addition, if the acceleration operation amount is limited in such a situation, it will give the driver a sense of discomfort, so the routine is exited without any restriction.

[0088] Then, if the process proceeds to step S24, based on the steering wheel angle θst and the vehicle speed V, the reference Figure 7 The acceleration suppression amount setting map shown is used to set the acceleration suppression amount. It should be noted that the processing in this step corresponds to the acceleration suppression amount setting unit of the present invention.

[0089] like Figure 7As shown in FIG. 1 , the acceleration suppression amount is set so that the ratio of suppressing acceleration (acceleration suppression amount) becomes larger as the steering wheel angle θst becomes larger and the vehicle speed V becomes higher. That is, when the driving mode is switched from a state of driving on a curved road with a large steering wheel angle θst at high speed to the manual driving mode, by increasing the acceleration suppression amount relative to the driver's accelerator pedal depression amount (accelerator opening θac), lane departure and the like caused by unnecessary acceleration can be prevented in advance.

[0090] Next, the process proceeds to step S25, where the automatic driving duration Tau is read, and then proceeds to step S26, where the automatic driving duration Tau is referenced based on the acceleration suppression amount and the automatic driving duration Tau. Figure 8 The accelerator operation speed threshold value setting map shown is used to set the accelerator operation speed threshold value ωsl [deg / sec]. It should be noted that the processing in this step corresponds to the accelerator operation speed threshold value setting unit of the present invention.

[0091] like Figure 8 As shown in FIG. 1 , the acceleration operation speed threshold ωsl is set to the upper limit value Hi before the acceleration suppression amount increases to a certain extent, and is set to the lower limit value Lo by decreasing from when the acceleration suppression amount increases to a certain extent. Therefore, when the acceleration suppression amount is low, since the acceleration operation speed threshold ωsl is set to the upper limit value Hi, the accelerator pedal stepping speed of the driver is not greatly limited. On the other hand, when the acceleration suppression amount is high, since the acceleration operation speed threshold ωsl is set to the lower limit value Lo, even if the driver steps on the accelerator pedal rapidly, sudden acceleration that the driver does not intend to do will not occur.

[0092] In addition, the portion of the upper limit value Hi of the acceleration operation speed threshold value ωsl gradually decreases to the position of the lower limit value Lo as the automatic driving duration Tau becomes longer. Therefore, even when the acceleration suppression amount is low, when the automatic driving duration Tau is long, that is, as the driver's feeling for the acceleration operation decreases, the acceleration operation speed threshold value ωsl is set to a low value.

[0093] Then, the routine proceeds to step S27, and the acceleration operation speed threshold value ωsl stored in the memory is updated using the acceleration operation speed threshold value ωsl(n) set this time, and the routine is exited. Here, (n) represents this time.

[0094] On the other hand, the acceleration suppression control process at the time of transition to manual driving in step S4 is performed according to Figure 5 In this subroutine, first, in step S31, the elapsed time Tma after the transition from the automatic driving mode to the manual driving mode is calculated, and in step S32, the elapsed time Tma is compared with the initial suppression determination time Tmo as the initial time.

[0095] The initial suppression determination time Tmo is a time for which acceleration suppression is performed, in other words, a time for determining that the driver's sense of acceleration operation has recovered. The initial suppression determination time Tmo is a preset fixed value such as 1 to 2 [min].

[0096] However, if the initial suppression determination time Tmo is extremely short, the acceleration suppression is released before the driver's sense of the acceleration operation is restored. On the other hand, if the initial suppression determination time Tmo is set longer than necessary, the acceleration suppression continues even though the driver's sense of the acceleration operation has been restored, which may give the driver a sense of discomfort. Therefore, the initial suppression determination time Tmo is set in advance by finding the optimal time based on experiments or the like.

[0097] Then, in the case of Tma<Tmo, the routine proceeds to step S33 to perform acceleration suppression control. In addition, in the case of Tma≥Tmo, since acceleration suppression control is not required, the routine is exited. Therefore, in the case of Tma≥Tmo, the normal manual driving mode is adopted, and the amount of the driver's accelerator pedal depression is determined based on the amount of the driver's accelerator pedal depression. Figure 6 The target acceleration αt is set based on the slope of the normal characteristic shown.

[0098] On the other hand, if the process proceeds to step S33, the time derivative of the accelerator opening θac [deg] detected by the accelerator opening sensor 34 is taken to calculate the accelerator operation speed ωac [deg / sec]. Next, the process proceeds to step S34, where the accelerator operation speed ωac is compared with the accelerator opening sensor 34. Figure 4 The processing in this step corresponds to the acceleration operation speed comparison unit of the present invention.

[0099] Then, if ωac>ωsl, it is determined that the driver has stepped on the accelerator pedal rapidly (accelerator operation speed ωac is too high), and the process proceeds to step S35. On the other hand, if ωac≤ωsl, the process branches to step S36.

[0100] If the process proceeds to step S35, the acceleration suppression characteristic is read and the process proceeds to step S37. Figure 6As shown in FIG. 1 , with respect to the acceleration suppression characteristic, the slope of the acceleration-acceleration characteristic is set in advance to a value close to 0, and the sudden acceleration caused by the driver's sudden acceleration operation is suppressed. That is, even if the slope of the acceleration-acceleration characteristic is set based on the automatic driving duration Tau, when the driver greatly steps on the accelerator pedal, it is set to the target acceleration corresponding thereto, so there is a case where the acceleration suddenly increases. Therefore, in such a case (ωac>ωsl), by setting the target acceleration corresponding to the acceleration opening based on the acceleration suppression characteristic, the sudden increase in acceleration is suppressed.

[0101] It should be noted that when the driver feels that the output does not increase even if he / she rapidly steps on the accelerator pedal, he / she may release (restore) the accelerator pedal once and then step on it again. Therefore, the program branches from step S34 to step S36, so that the state where the slope of the acceleration-acceleration characteristic is close to 0 will not continue.

[0102] In addition, if the branch is to step S36, then read Figure 3 The latest acceleration-acceleration characteristics updated in step S14 are input to step S37.

[0103] If the routine proceeds to step S37, the target acceleration αt is set based on the accelerator opening θac detected by the accelerator opening sensor 34, with reference to the acceleration suppression characteristic or the acceleration-acceleration characteristic, and the routine is exited. The processing in steps S35 to S37 corresponds to the target acceleration setting unit of the present invention.

[0104] When the driving mode changes from the automatic driving mode to the manual driving mode, the driving control unit 11 calculates the output of the driving source (engine, electric motor) corresponding to the target acceleration αt, and outputs the corresponding driving signal to the acceleration / deceleration driving unit 42, thereby driving the driving source in a predetermined manner.

[0105] Thus, according to the present embodiment, when the driving mode is changed from the automatic driving mode to the manual driving mode, the longer the automatic driving duration Tau in the automatic driving mode is, the smaller the slope of the target acceleration αt of the acceleration-acceleration characteristic relative to the acceleration opening θac is made. Therefore, even if the driver's feeling for the acceleration operation is reduced when changing to the manual driving mode due to the long automatic driving duration Tau and the driver mistakenly performs excessive acceleration operation, unintentional sudden acceleration by the driver will not occur, and the driver will not feel uncomfortable.

[0106] In addition, when the automatic driving mode is switched to the manual driving mode within a short time (Tau<Tao) after the start of the automatic driving mode, the slope of the target acceleration αt of the acceleration-acceleration characteristic relative to the acceleration opening θac remains the normal characteristic. Therefore, a driving force corresponding to the driver's acceleration operation can be generated without causing discomfort to the driver.

[0107] Furthermore, when the driving mode changes from the automatic driving mode to the manual driving mode, if the driver suddenly steps on the accelerator pedal, the slope of the target acceleration αt of the acceleration-acceleration characteristic relative to the acceleration opening θac is set to a value almost close to 0, thereby suppressing sudden acceleration caused by the sudden acceleration operation.

[0108] It should be noted that the present invention is not limited to the above-mentioned embodiments. Figure 5 In the acceleration suppression control subroutine for transition to manual driving shown in FIG. 1 , after the elapsed time Tma exceeds the initial suppression determination time Tmo (Tma ≥ Tmo), the acceleration-acceleration characteristic for limiting the target acceleration αt may be gradually shifted to Figure 6 The usual characteristics of the direction shown are restored.

Claims

1. A vehicle travel control device, characterized in that: have: an accelerator operation amount detection unit that detects an accelerator operation amount of a driver; a driving mode determination unit having an automatic driving mode in which the vehicle autonomously drives along a target travel path and a manual driving mode in which the driver performs a driving operation as driving modes, and determining whether the current driving mode is the automatic driving mode or the manual driving mode based on driving conditions; an automatic driving duration calculation unit for calculating a duration of the automatic driving mode when the driving mode determination unit determines that the driving mode is the automatic driving mode; an acceleration characteristic setting unit that variably sets a characteristic of a target acceleration with respect to the acceleration operation amount detected by the acceleration operation amount detection unit based on the duration calculated by the automatic driving duration calculation unit; as well as A target acceleration setting unit sets the target acceleration corresponding to the acceleration operation amount detected by the acceleration operation amount detection unit by referring to the characteristic of the target acceleration set by the acceleration characteristic setting unit relative to the acceleration operation amount when the driving mode determination unit determines that the driving mode has changed from the automatic driving mode to the manual driving mode.

2. The vehicle travel control device according to claim 1, characterized in that: The target acceleration setting unit sets the target acceleration corresponding to the acceleration operation amount detected by the acceleration operation amount detection unit during a preset initial time when the driving mode determination unit determines that the driving mode is changed from the automatic driving mode to the manual driving mode.

3. The vehicle travel control device according to claim 1, characterized in that: The acceleration characteristic setting unit sets a characteristic of a target acceleration with respect to the accelerator operation amount to be lower as the duration is longer, based on the duration calculated by the automatic driving duration calculation unit.

4. The vehicle travel control device according to claim 2, characterized in that: The acceleration characteristic setting unit sets a characteristic of a target acceleration with respect to the accelerator operation amount to be lower as the duration is longer, based on the duration calculated by the automatic driving duration calculation unit.

5. The vehicle travel control device according to any one of claims 1 to 4, characterized in that: The vehicle travel control device further includes a driving mode selection unit for selecting the manual driving mode and the automatic driving mode through external operation. The driving condition read by the driving mode determination unit is the driving mode selected by the driving mode selection unit or the accelerator operation amount detected by the accelerator operation amount detection unit, The driving mode determination unit determines that the driving mode is the manual driving mode when the manual driving mode is selected by the driving mode selection unit or when the driver detects that an accelerator pedal is depressed based on the accelerator operation amount detected by the accelerator operation amount detection unit.

6. The vehicle travel control device according to any one of claims 1 to 4, characterized in that: The vehicle travel control device further comprises: a steering wheel angle detection unit, which detects a steering wheel angle; A vehicle speed detection unit, which detects the vehicle speed; an acceleration suppression amount setting unit that sets an acceleration suppression amount based on the steering wheel angle detected by the steering wheel angle detection unit and the host vehicle speed detected by the host vehicle speed detection unit; an acceleration operation speed threshold value setting unit that sets an acceleration operation speed threshold value based on the acceleration suppression amount set by the acceleration suppression amount setting unit, the acceleration operation speed threshold value being a threshold value for determining whether an acceleration operation speed obtained based on the acceleration operation amount detected by the acceleration operation amount detection unit is excessive; as well as an acceleration operation speed comparison unit that compares the acceleration operation speed threshold value set by the acceleration operation speed threshold value setting unit with the acceleration operation speed, The target acceleration setting unit refers to the characteristic of the target acceleration with respect to the accelerator operation amount when the accelerator operation speed comparison unit determines that the accelerator operation speed is equal to or less than the accelerator operation speed threshold value.

7. The vehicle travel control device according to claim 6, characterized in that: The target acceleration setting unit sets the target acceleration to a value close to zero when the accelerator operation speed comparison unit determines that the accelerator operation speed exceeds the accelerator operation speed threshold value.

8. The vehicle travel control device according to claim 6, characterized in that: The accelerator operation speed threshold value set by the accelerator operation speed threshold value setting unit is set to a lower value as the duration calculated by the automatic driving duration calculation unit becomes longer.

9. The vehicle travel control device according to claim 7, characterized in that: The accelerator operation speed threshold value set by the accelerator operation speed threshold value setting unit is set to a lower value as the duration calculated by the automatic driving duration calculation unit becomes longer.

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