CN210416544U - Vehicle travel control device - Google Patents

Abstract

The utility model discloses a vehicle travel control device, when crossing the segment difference and traveling, prevent to bring harmful effects to traveling of rear vehicle. A vehicle travel control device (50) is provided with: a step detector (51) for detecting a step on a road surface ahead in the direction of travel; a target vehicle speed setting unit (401) that sets a target vehicle speed when the level difference is reached, in accordance with the shape of the level difference detected by the level difference detector (51); a transmission control unit (403) and a throttle control unit (404) that control the transmission actuator (61) and the throttle actuator (62) so that the vehicle speed decreases to or below the target vehicle speed when the level difference is reached; and a rear vehicle detector (53) that detects a rear vehicle. When a rear vehicle is detected by a rear vehicle detector (53), a transmission control unit (403) and a throttle control unit (404) reduce the vehicle speed to a target vehicle speed or less at a deceleration at which the magnitude of the deceleration becomes a predetermined value or less.

Description

Vehicle travel control device

Technical Field

The utility model relates to a vehicle travel control device that action when going is carried out to crossing the segment difference controls.

Background

As such a device, the following devices have been known: the shape of a convex portion existing on a road surface ahead of a vehicle is detected by a camera or the like, and driving of the vehicle is controlled based on the detected shape of the convex portion (for example, see patent document 1). In the device described in patent document 1, a first point in front of the convex portion, which is located at a first distance from the convex portion, and a second point in front of the first point, which is located at a second distance from the first point, are set, respectively, and the vehicle is decelerated in accordance with the shape of the convex portion while the vehicle travels from the second point to the first point, and when the vehicle reaches the first point, the deceleration is released and the vehicle passes over the convex portion.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent laid-open No. 2008-1302

SUMMERY OF THE UTILITY MODEL

[ problem to be solved by the utility model ]

However, if the vehicle is decelerated in front of the convex portion as in the device described in patent document 1, there is a possibility that the driver of the rear vehicle is forced to perform sudden deceleration of the vehicle, or the like, which may adversely affect the traveling of the rear vehicle.

[ means for solving problems ]

An embodiment of the present invention is a vehicle travel control device that controls a vehicle having a travel driving unit that generates travel driving force, the vehicle travel control device including: a step detection unit that detects a step of a road surface ahead in a traveling direction; a target vehicle speed setting unit that sets a target vehicle speed when the level difference is reached, in accordance with the shape of the level difference detected by the level difference detection unit; a control unit that controls the travel drive unit so that the vehicle speed decreases to a target vehicle speed or less when the level difference is reached; and a rear vehicle detection unit that detects a rear vehicle. When the rear vehicle is detected by the rear vehicle detection unit, the control unit reduces the vehicle speed to the target vehicle speed or less at a deceleration at which the magnitude of the deceleration becomes a predetermined value or less.

The vehicle travel control device according to the above aspect of the invention may be configured such that the travel driving unit includes an internal combustion engine and a transmission connected to the internal combustion engine, and the control unit controls the gear ratio of the transmission so that the vehicle speed is reduced to the target vehicle speed or less by a braking action of the internal combustion engine.

The vehicle travel control device according to the above aspect of the invention further includes an acceleration/deceleration operation detection unit that detects an acceleration operation or a deceleration operation input by a driver, wherein the control unit controls the travel drive unit so that the travel drive force increases to a predetermined overshoot drive force after a tire of the vehicle has abutted against the step, and corrects the predetermined overshoot drive force when a next step is passed in response to the detected acceleration operation or deceleration operation when the acceleration operation or deceleration operation is detected by the acceleration/deceleration operation detection unit after the tire has abutted against the step.

[ effects of the utility model ]

According to the utility model discloses, can prevent to cross the traveling of rear vehicle when the section difference and bring harmful effects.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a travel drive system of an autonomous vehicle to which a vehicle travel control device according to an embodiment of the present invention is applied.

Fig. 2 is a block diagram schematically showing the overall configuration of a vehicle control system that controls the autonomous vehicle of fig. 1.

Fig. 3 is a diagram showing an example of the operation of the vehicle travel control device to which the embodiment of the present invention is applied.

Fig. 4 is a block diagram showing a configuration of a main part of a vehicle travel control device according to an embodiment of the present invention.

Fig. 5 is a diagram for explaining a method for determining the shape of the level difference by the vehicle travel control device of fig. 4.

Fig. 6 is a diagram showing a relationship between the accelerator pedal operation amount and the correction coefficient of the overshoot drive force.

Fig. 7 is a flowchart showing an example of processing executed by the controller of fig. 4.

Fig. 8 is a flowchart showing an example of another process executed by the controller of fig. 4.

Fig. 9A is a timing chart showing an example of the operation performed by the vehicle travel control device according to the embodiment of the present invention.

Fig. 9B is a timing chart showing another example of the operation performed by the vehicle travel control device according to the embodiment of the present invention.

Description of the symbols

1: engine

2: speed variator

40: controller

50: vehicle travel control device

51: segment difference detector

53: rear vehicle detector

55: acceleration/deceleration operation detector

61: actuator for transmission

62: actuator for throttling

100: autonomous vehicle

401: target vehicle speed setting unit

402: driving force setting unit

403: transmission control unit

404: throttle control part

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to fig. 1 to 9B. The utility model discloses vehicle travel control device of embodiment is applied to the vehicle (automatic driving vehicle) that has the autopilot function. First, the configuration of the autonomous vehicle will be described. Fig. 1 is a diagram showing a schematic configuration of a travel drive system of an autonomous vehicle 100 (which may be simply referred to as a vehicle) to which a vehicle travel control device according to the present embodiment is applied. The vehicle 100 can realize not only traveling in the automatic driving mode in which driving operation by a driver is not required but also traveling in the manual driving mode in which driving operation by a driver is utilized.

As shown in fig. 1, the vehicle 100 includes an engine 1 and a transmission 2 arranged in an engine room at a Front portion of a vehicle body, and is configured as a Front-engine Front drive (FF) type vehicle in which, for example, Front wheels are drive wheels and rear wheels are driven wheels. The driving method of vehicle 100 is not limited to this, and for example, the rear wheels may be used as the driving wheels and the front wheels may be used as the driven wheels, or the four wheels may be used as the driving wheels.

The engine 1 is an internal combustion engine (for example, a gasoline engine) that generates rotational power by mixing intake air supplied via a throttle valve 11 and fuel injected from an injector 12 at an appropriate ratio, igniting the mixture with a spark plug or the like, and combusting the mixture. Various engines such as a diesel engine may be used instead of the gasoline engine. The intake air amount is adjusted by a throttle valve 11, and the opening degree of the throttle valve 11 is changed by driving a throttle actuator that operates by an electric signal.

The transmission 2 is provided in a power transmission path between the engine 1 and the drive wheels 3, and changes the speed of rotation from the engine 1 and converts the torque from the engine 1 to output the converted torque. The rotation shifted by the transmission 2 is transmitted to the left and right drive wheels 3 via the differential mechanism, whereby the vehicle 100 travels. Alternatively, vehicle 100 may be configured as an electric vehicle or a hybrid vehicle by providing a travel motor as a drive source instead of engine 1 or in addition to engine 1.

The transmission 2 is, for example, a stepped transmission capable of changing a transmission ratio stepwise in accordance with a plurality of gear positions. A continuously variable transmission that can change the transmission ratio without a step may be used as the transmission 2. Although not shown, the power from the engine 1 may be input to the transmission 2 via a torque converter. The transmission 2 includes an engagement element 21 such as a dog clutch (dog clutch) or a friction clutch, for example, and the hydraulic control device 22 controls the flow of oil to the engagement element 21, thereby making it possible to change the gear position of the transmission 2.

The brake device 4 includes, for example, a disc brake that operates by oil pressure, and the rotation of the drive wheels 3 can be forcibly stopped by the operation of the brake device 4.

Fig. 2 is a block diagram schematically showing the overall configuration of a vehicle control system 101 that controls the autonomous vehicle 100 of fig. 1. As shown in fig. 2, the vehicle control system 101 mainly includes: the controller 40, and an external sensor group 31, an internal sensor group 32, an input/output device 33, a Global Positioning System (GPS) receiver 34, a map database 35, a navigation device 36, a communication unit 37, and a travel actuator AC, which are electrically connected to the controller 40, respectively.

The external sensor group 31 is a general term for a plurality of sensors that detect external conditions as peripheral information of the vehicle 100. For example, the external sensor group 31 includes: a laser radar that measures scattered light of the vehicle 100 with respect to the irradiation light in all directions to measure a distance from the vehicle 100 to a surrounding obstacle; a radar that detects other vehicles, obstacles, and the like around the vehicle 100 by irradiating electromagnetic waves and detecting reflected waves; the camera is mounted on the vehicle 100, includes an imaging Device such as a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS), and captures the periphery (front, rear, and side) of the vehicle 100.

The internal sensor group 32 is a general term for a plurality of sensors that detect the traveling state of the vehicle 100. For example, the internal sensor group 32 includes: a vehicle speed sensor that detects a vehicle speed of vehicle 100, an acceleration sensor that detects acceleration in the front-rear direction and acceleration in the left-right direction of vehicle 100, an engine speed sensor that detects a speed of engine 1, a yaw rate sensor that detects a rotational angular velocity of the center of gravity of vehicle 100 about a vertical axis, a throttle opening sensor that detects an opening degree (throttle opening degree) of throttle valve 11, and the like. The internal sensor group 32 also includes sensors for detecting driving operations of the driver in the manual driving mode, for example, operations of operating members such as an accelerator pedal, a brake pedal, and a steering wheel.

The input/output device 33 is a generic term for a device that inputs an instruction from a driver or outputs information to the driver. For example, the input/output device 33 includes: various switches through which a driver inputs various instructions by operation of an operation member, a microphone through which a driver inputs instructions by sound, a display portion that provides information to the driver via a display image, a speaker that provides information to the driver by sound, and the like. The various switches include a manual automatic changeover switch indicating any one of an automatic driving mode and a manual driving mode.

The manual/automatic changeover switch is configured as a switch that can be manually operated by a driver, for example, and outputs a changeover command for an automatic driving mode for activating the automatic driving function or a manual driving mode for deactivating the automatic driving function in response to a switch operation. When the predetermined running condition is not established by the operation of the manual/automatic changeover switch, the instruction may be made to change over from the manual driving mode to the automatic driving mode or from the automatic driving mode to the manual driving mode. That is, the mode switching may be performed automatically, not manually, by automatically switching the mode by a manual/automatic switching switch.

The GPS receiver (GPS sensor) 34 receives positioning signals from a plurality of GPS satellites, and measures the absolute position (latitude, longitude, and the like) of the vehicle 100.

The map database 35 is a device that stores general map information used in the navigation device 36, and includes, for example, a hard disk. The map information includes position information of a road, information of a road shape (curvature, etc.), and position information of an intersection or a branch point. The map information stored in the map database 35 is different from the map information stored in the storage unit 42 of the controller 40 with high accuracy.

The navigation device 36 is a device that searches for a target route on a road to a destination input by a driver and performs guidance along the target route. The input of the destination and the guidance along the target route are performed via the input/output device 33. The target route is calculated from the current position of the vehicle measured by the GPS receiver 34 and the map information stored in the map database 35.

The communication unit 37 communicates with various servers not shown via a network including a wireless communication network such as an internet line, and acquires map information, traffic information, and the like from the servers periodically or at an arbitrary timing. The acquired map information is output to the map database 35 or the storage unit 42, and the map information is updated. The acquired traffic information includes signal information such as congestion information or a remaining time until a signal changes from red to green.

The actuator AC is a travel actuator for controlling travel of the vehicle 100. The actuator AC includes various actuators operated by electric signals from the controller 40. Examples include: a throttle actuator that adjusts the opening degree of the throttle valve 11 of the engine 1, a transmission actuator that changes the gear position of the transmission 2 by controlling the flow of oil to the engagement element 21 of the transmission 2, a brake actuator that operates the brake device 4, and a steering actuator that drives the steering device.

The controller 40 includes an Electronic Control Unit (ECU). Further, although a plurality of ECUs having different functions, such as an engine control ECU and a transmission control ECU, may be provided separately, fig. 2 shows a controller 40 as a set of these ECUs for convenience of explanation. The controller 40 includes a computer having a calculation Unit 41 such as a Central Processing Unit (CPU), a storage Unit 42 such as a Read Only Memory (ROM), a Random Access Memory (RAM), and a hard disk, and other peripheral circuits (not shown).

The storage unit 42 stores highly accurate detailed map information including information on the center position of the lane, information on the boundary of the lane position, and the like. More specifically, as the map information, road information, traffic control information, address information, facility information, telephone number information, parking lot information, and the like are stored. The road information includes information indicating the type of a road such as an expressway, a toll road, and a national road, and information such as the number of lanes on the road, the width of each lane, the gradient of the road, the three-dimensional coordinate position of the road, the curvature of a turn of the lane, the positions of a merging point and a diverging point of the lane, and a road sign. The traffic control information includes information for restricting or prohibiting the travel of a lane by a construction or the like. The storage unit 42 also stores information such as a shift map (shift line map) serving as a reference of the shifting operation, programs of various controls, and thresholds used in the programs.

The calculation unit 41 includes a vehicle position recognition unit 43, an external recognition unit 44, an action plan generation unit 45, and a travel control unit 46 as functions.

The vehicle position recognition unit 43 recognizes the position of the vehicle 100 (the vehicle position) on the map based on the position information of the vehicle 100 received by the GPS receiver 34 and the map information of the map database 35. The vehicle position may be identified with high accuracy by identifying the vehicle position using the map information (information such as the shape of the building) stored in the storage unit 42 and the information on the surroundings of the vehicle 100 detected by the external sensor group 31. In addition, when the vehicle position can be measured by an external sensor provided on the road or near the road, the vehicle position can be recognized with high accuracy by communicating with the sensor via the communication unit 37.

The environment recognition unit 44 recognizes an external situation around the vehicle 100 based on signals from the external sensor group 31 such as a laser radar, a radar, and a camera. For example, the position, speed, or acceleration of a nearby vehicle (a preceding vehicle or a following vehicle) traveling around the vehicle 100, the position of a nearby vehicle that is stopping or parking around the vehicle 100, the position or state of another object, and the like are recognized. Other objects include signs, semaphores, boundary lines or stop lines for roads, buildings, guardrails, utility poles, signs, pedestrians, bicycles, convex or concave steps on a road surface, and the like. The state of the other object includes the color of the traffic signal (red, green, yellow), the moving speed or direction of the pedestrian or the bicycle, the shape of the step on the road surface, and the like.

The action plan generating unit 45 generates a travel track (target track) of the vehicle 100 from the current time point to a predetermined time point, for example, based on the target route calculated by the navigation device 36, the vehicle position recognized by the vehicle position recognizing unit 43, and the external situation recognized by the external environment recognizing unit 44. When a plurality of tracks that are candidates for the target track exist on the target route, the action plan generating unit 45 selects an optimum track that satisfies the compliance act and that efficiently and safely travels or the like from among the tracks, and sets the selected track as the target track. Then, the action plan generating unit 45 generates an action plan corresponding to the generated target trajectory.

The action plan includes travel plan data set per unit time (for example, 0.1 second) from the current time point to a predetermined time (for example, 5 seconds), that is, travel plan data set in association with the time per unit time. The travel plan data includes position data of the vehicle 100 per unit time and data of the vehicle state. The position data is, for example, data of a target point indicating a two-dimensional coordinate position on a road, and the vehicle state data is vehicle speed data indicating a vehicle speed, direction data indicating a direction of the vehicle 100, and the like. The travel plan is updated per unit time.

The action plan generating unit 45 generates the target trajectory by connecting the position data per unit time from the current time point to a predetermined time (for example, 5 seconds) in time series. At this time, an acceleration per unit time (target acceleration) is calculated from the vehicle speed of each target point per unit time on the target track (target vehicle speed). That is, the action plan generating unit 45 calculates the target vehicle speed and the target acceleration. The target acceleration may be calculated by the travel control unit 46.

In the automatic driving mode, the travel control unit 46 controls the actuator AC so that the vehicle 100 travels along the target trajectory generated by the action plan generating unit 45 at the target vehicle speed and the target acceleration. That is, the throttle actuator, the transmission actuator, the brake actuator, the steering actuator, and the like are controlled so that the vehicle 100 passes through the target point per unit time. In the manual driving, the travel control portion 46 controls the actuator AC in correspondence to the driving operation of the driver detected by the interior sensor group 32. When an operating member such as an accelerator pedal or a brake pedal has been operated at the time of automatic driving, the travel control portion 46 controls the actuator AC in correspondence with the operation of the operating member.

Fig. 3 is a diagram showing an example of the operation of the vehicle travel control device to which the embodiment of the present invention is applied. As shown in fig. 3, the vehicle travel control means is applied when a vehicle 100 that is traveling in the direction of an arrow a1 by autonomous driving crosses a step 102 on a road surface 103 located in front of the vehicle. Further, at the rear of the vehicle 100, the rear vehicle 200 is traveling toward the vehicle 100 as indicated by an arrow a 2. The level difference 102 is a protrusion provided on the road surface 103 to accelerate deceleration of the vehicle 100, and is called, for example, a speed bump (speed breaker) or a speed bump. When the impact when the vehicle passes over the step 102 is large, discomfort is given to the occupant. Therefore, the vehicle 100 decelerates sufficiently in front of the level difference 102 to mitigate the impact when passing over the level difference.

However, if the deceleration of the vehicle 100 is large when the rear vehicle 200 is present, the traveling of the rear vehicle 200 may be adversely affected, for example, by an operation of forcing the driver of the rear vehicle 200 to decelerate suddenly. In view of this, the present embodiment constitutes a vehicle travel control device as follows.

Fig. 4 is a block diagram showing a main part configuration of a vehicle travel control device 50 according to the present embodiment. The vehicle travel control device 50 is a device that controls the travel operation of the vehicle 100 so as to cross the step 102 by automatic driving, and constitutes a part of the vehicle control system 101 of fig. 2.

As shown in fig. 4, the vehicle travel control device 50 is configured with the controller 40 as the center, and includes: the step difference detector 51, the distance detector 52, the rear vehicle detector 53, the vehicle speed detector 54, and the acceleration/deceleration operation detector 55, which are input signals to the controller 40, and the transmission actuator 61, the throttle actuator 62, and the brake actuator 63, which are output control signals from the controller 40.

The level difference detector 51 is a detector that detects a level difference 102 on a road surface 103 in front of the vehicle 100. The distance detector 52 is a detector that detects the distance from the vehicle 100 to the level difference 102, and for example, as shown in fig. 3, detects the distance Δ X1 from the vehicle 100 to a point P0 (level difference contact point) where the tire contacts the level difference 102, and the distance from the vehicle 100 to each point P1 to a point P4 (fig. 5) of the level difference 102. The rear vehicle detector 53 is a detector that detects the rear vehicle 200 and detects the distance (Δ X2 in fig. 3) from the vehicle 100 to the rear vehicle 200. The level difference detector 51, the distance detector 52, and the rear vehicle detector 53 are part of the external sensor group 31 in fig. 2, and include a camera, a laser radar, a radar, and the like.

The vehicle speed detector 54 is a detector that detects the vehicle speed of the vehicle 100. The acceleration/deceleration operation detector 55 is a detector that detects an operation amount of an accelerator pedal (acceleration operation) and an operation amount of a brake pedal (deceleration operation). The vehicle speed detector 54 and the acceleration/deceleration operation detector 55 form a part of the internal sensor group 32 in fig. 2. The transmission actuator 61, the throttle actuator 62, the brake actuator 63, and the steering actuator 64 constitute a part of the actuator AC of fig. 2.

The controller 40 includes a target vehicle speed setting unit 401, a driving force setting unit 402, a transmission control unit 403, a throttle control unit 404, and a brake control unit 405. Target vehicle speed setting unit 401 and driving force setting unit 402 constitute, for example, a part of action plan generating unit 45 in fig. 2. The transmission control unit 403, the throttle control unit 404, and the brake control unit 405 constitute, for example, a part of the travel control unit 46 in fig. 2. The configuration of each part of the controller 40 shown in fig. 4 will be described in detail below.

The target vehicle speed setting unit 401 first determines the shape of the level difference 102 detected by the level difference detector 51. Fig. 5 is a diagram illustrating a method for determining the shape of the level difference 102. As shown in fig. 5, the traveling direction of the vehicle 100 along the road surface 103 is defined as the X direction, and the direction perpendicular to the road surface 103 is defined as the Y direction. At this time, the step 102 is divided in the X direction into a step start portion 102a (point P1 to point P2) where the step 102 starts, a straight portion 102b (point P2 to point P3) parallel to the road surface 103, and a step end portion 102c (point P3 to point P4) where the step 102 ends.

The level difference 102 is approximated to the level difference 102 (broken line) by an ellipse Q1 having a major diameter equal to twice the height h of the level difference 102 from the road surface 103 and a minor diameter equal to twice the length in the X direction from the level difference start point P1 on the road surface 103 to a point P2 which is the apex of the level difference 102, the level difference start unit 102a being an ellipse Q1. The level difference ending part 102c is defined as a shape symmetrical in the X direction with respect to the level difference starting part 102 a. The level difference 102 may be approximated by a 1/4 circle Q2 having a radius equal to the height h of the level difference 102, with the level difference starting portion 102a and the level difference ending portion 102c (broken line). As described above, by detecting the points P1 to P3 by the level difference detector 51, the target vehicle speed setting unit 401 can specify the shape of the level difference 102.

Then, the target vehicle speed setting unit 401 calculates the target vehicle speed when the step 102 is passed, based on the determined step shape. Specifically, first, an upper limit value (upper limit impact force) F1 of the impact force that vehicle 100 receives from step 102 when vehicle 100 (tire) hits step 102 is set. Further, the degree of discomfort of the occupant increases as the impact force increases, and the upper limit impact force F1 is set to a value corresponding to the degree of discomfort tolerable by the occupant. Then, the target vehicle speed setting unit 401 calculates a target vehicle speed at which the impact force at the time point when the tire abuts against the step 102 (referred to as a step abutment time point) becomes equal to or less than an upper limit impact force F1, that is, an upper limit value (upper limit vehicle speed) Va1 of a target vehicle speed Va at the step abutment time point (referred to as a final target vehicle speed).

That is, the impact force has a correlation with the shape of the step 102 and the amount of movement of the vehicle 100 immediately before the step 102 is hit, and the longer the major diameter and the shorter the minor diameter of the step 102 are, the heavier the vehicle weight is, and the faster the vehicle speed is, the larger the impact force becomes. Therefore, in consideration of this point, the relationship (characteristic map or relational expression) between the shape of the step 102 corresponding to the upper limit impact force F1 and the upper limit vehicle speed Va1 when the vehicle weight is fixed is stored in advance, and the target vehicle speed setting unit 401 calculates the upper limit vehicle speed Va1 corresponding to the shape of the step 102 using the stored relationship. Further, the final target vehicle speed Va at the level difference arrival time point is set within a range not exceeding the upper limit vehicle speed Va 1.

In this case, before the collision with the stepped difference, the target vehicle speed setting unit 401 determines whether or not the rear vehicle 200 is present within the predetermined distance Δ X3 from the vehicle 100, that is, whether or not the distance Δ X2 detected by the rear vehicle detector 53 is equal to or less than the predetermined distance Δ X3, as shown in fig. 3, based on the signal from the rear vehicle detector 53. The predetermined distance Δ X3 is a threshold value of the inter-vehicle distance at which adverse effects such as sudden deceleration of the driver of the rear vehicle 200 may be caused by the decelerated travel of the vehicle 100 when the vehicle crosses the step. For example, the predetermined distance Δ X3 is set to a larger value as the vehicle speed detected by the vehicle speed detector 54 is faster.

When determining that the rear vehicle 200 is within the predetermined distance Δ X3, the target vehicle speed setting unit 401 calculates a deceleration time during which the magnitude of the deceleration becomes the predetermined value α 1, that is, the minimum deceleration time Δ t1, the predetermined value α 1, based on the current vehicle speed detected by the vehicle speed detector 54 and the final target vehicle speed (for example, the upper limit vehicle speed Va1), so as not to exert an adverse effect such as rapid deceleration on the operation of the driver of the rear vehicle 200, and when the magnitude of the deceleration of the vehicle 100 is equal to or less than the predetermined value α 1, the magnitude of the deceleration of the rear vehicle 200 can be suppressed to or less than the predetermined value α 1, thereby suppressing an adverse effect on the traveling of the rear vehicle 200.

Further, when the rear vehicle 200 is within the predetermined distance Δ X3, the target vehicle speed setting unit 401 sets the target vehicle speed per unit time included in the action plan so as to decelerate to the final target vehicle speed Va at a fixed rate within the predetermined deceleration time Δ t, for example, sets the target vehicle speed per unit time during the period from the deceleration start point to the deceleration end point in such a manner that the deceleration is completed at the step difference reaching time point and the target vehicle speed becomes the final target vehicle speed Va, sets the target vehicle speed per unit time during the period from the deceleration start point to the deceleration end point, in this case, the target vehicle speed setting unit 401 sets the deceleration time Δ t to be equal to or longer than the minimum deceleration time Δ t1 (for example, the minimum deceleration time Δ t1), and sets the deceleration time Δ t to be equal to or longer than the minimum deceleration time Δ t1, thereby setting the magnitude of the deceleration to be equal to or shorter than the predetermined value α 1, and sets the step difference from the deceleration start point to the deceleration end point to be a deceleration section.

The driving force setting unit 402 sets the overshoot driving force Fa for striking up the stepped portion 102 after reaching the stepped portion, for example, the smaller the vehicle speed (final target vehicle speed Va) at the stepped portion contact time point and the smaller the amount of movement at the time of striking up the stepped portion, and the larger the height h of the stepped portion 102, in accordance with the shape of the stepped portion 102 detected by the stepped portion detector 51 and the vehicle speed at the stepped portion contact time point of the tire, and when a correction coefficient β relating to the overshoot driving force Fa is set in advance, the driving force setting unit 402 calculates a correction value Δ Fa of the overshoot driving force Fa using the correction coefficient β, and corrects the overshoot driving force Fa using the correction value Δ Fa.

In this case, first, it is determined whether there is an operation of the accelerator pedal and an operation of the brake pedal when the step is crossed (for example, between the point P1 and the point P2 in fig. 5) based on the signal from the acceleration/deceleration operation detector 55, that is, whether the driver is satisfied with the behavior of the vehicle 100 when the step is crossed, that is, when the driver feels that the driving force is insufficient when the step is crossed, the driver operates the accelerator pedal when the step is crossed, and conversely when the driving force is excessive, the driver operates the brake pedal when the step is crossed, thereby causing an automatic driving to be performed, and therefore, when the accelerator pedal or the brake pedal is operated, the correction coefficient β is calculated in accordance with the operation amount thereof.

Fig. 6 is a diagram showing the relationship between the amount of operation S of the accelerator pedal and the correction coefficient β, as shown in fig. 6, the correction coefficient β is set in the range of 0 to 1, and the correction coefficient β gradually increases from 0 to 1 with an increase in the amount of operation S of the accelerator pedal, and further, although not shown, the relationship between the amount of operation of the brake pedal and the correction coefficient β is different from that of fig. 6, and the correction coefficient β is set in the range of-1 to 0, and the correction coefficient β gradually decreases with an increase in the amount of operation of the brake pedal.

When the vehicle 100 again crosses the same step 102, the driving force setting unit 402 multiplies the overshoot driving force Fa by the correction coefficient β to calculate the correction value Δ Fa, and adds the overshoot driving force Fa to the correction value Δ Fa to correct the overshoot driving force Fa.

The transmission control unit 403 calculates the degree of change in the target vehicle speed, that is, the deceleration, within the deceleration time Δ t, based on the target vehicle speed per unit time set by the target vehicle speed setting unit 401. Further, a target deceleration force corresponding to the deceleration is calculated, and a control signal is output to the transmission actuator 61 to set the gear position of the transmission 2 so that the target deceleration force is obtained by engine braking. In this case, the transmission 2 is controlled to be lower in consideration of the fact that the lower the shift stage of the transmission 2, the greater the engine braking force can be obtained, and the greater the target deceleration force. For example, when the target deceleration force is a value between the deceleration force obtained at the fourth speed stage and the deceleration force obtained at the fifth speed stage, the shift stage is controlled to the fourth speed stage. Therefore, in the deceleration section corresponding to the deceleration time Δ t, the vehicle can be decelerated to the final target vehicle speed Va without operating the brake device 4.

The throttle control unit 404 outputs a control signal to the throttle actuator 62 to control the opening degree of the throttle valve 11 so that the vehicle speed changes in accordance with the target vehicle speed set by the target vehicle speed setting unit 401. When the tire kick-up step 102 occurs, the opening degree of the throttle valve 11 is controlled so as to generate the kick-up driving force Fa set by the driving force setting section 402.

The brake control unit 405 outputs a control signal to the brake actuator 63 so that the vehicle speed does not exceed the target vehicle speed, and controls the operation of the brake device 4. For example, when the tire falls from the step 102 (point P3 to point P4 in fig. 5), the vehicle 100 is accelerated by gravity, and in this case, the brake device 4 is operated so that the actual vehicle speed does not exceed the target vehicle speed.

Fig. 7 is a flowchart showing an example of processing executed by the controller 40 of fig. 4. In the course of the vehicle 100 running by the automated driving, if the level difference 102 is detected on the road surface 103 by the level difference detector 51, the processing shown in this flowchart is started.

First, in step S1, the shape of the level difference 102 is determined from the signal from the level difference detector 51. Next, in step S2, the final target vehicle speed Va at the time point when the level difference reaches is set so as not to give discomfort to the occupant, in accordance with the shape of the level difference 102. The upper limit vehicle speed Va1 is set to the final target vehicle speed Va, for example. Then, in step S3, it is determined whether or not the rear vehicle 200 is present within the predetermined distance Δ X3, based on the signal from the rear vehicle detector 53. If yes in step S3, the process proceeds to step S4, and if no in step S3, the process proceeds to step S5, skipping step S4.

In step S4, the minimum deceleration time Δ t1 is calculated in which the magnitude of deceleration becomes the predetermined value α 1. in step S5, the target vehicle speed is set such that the step difference arrival time becomes the target vehicle speed per unit time of the final target vehicle speed Va set in step S2. in this case, when the minimum deceleration time Δ t1 is calculated in step S4, the deceleration time Δ t equal to or longer than the minimum deceleration time Δ t1 is set, and the target vehicle speed per unit time within the deceleration time Δ t is set.

Then, in step S6, it is determined whether the vehicle 100 (tires) has reached the deceleration start point, that is, the point at which the target vehicle speed set in step S5 has decreased, based on the signal from the distance detector 52. if yes in step S6, the process proceeds to step S7, and if no in step S6, the process proceeds to step S8, skipping step S7. in step S7, the deceleration (target acceleration) within the deceleration time Δ t is calculated based on the target vehicle speed set in step S5. as described above, the deceleration time Δ t is set to the minimum deceleration time Δ t1 or more, and therefore the magnitude of the deceleration calculated in step S7 becomes the predetermined value α 1 or less.

Then, in step S8, a deceleration force corresponding to the deceleration calculated in step S7 is calculated, and a target gear position at which the deceleration force can be obtained by engine braking is calculated. Before reaching the deceleration start point (in the case of no at step S6), at step S8, a target gear is calculated according to the vehicle speed and the required driving force in accordance with a predetermined shift map. Then, in step S9, a control signal is output to the transmission actuator 61 to control the shift speed of the transmission 2 to the target shift speed. For example, the shift stage is controlled to the target shift stage at the deceleration start time point that is earlier than the step difference arrival time point by the deceleration time Δ t.

Then, in step S10, a control signal is output to the throttle actuator 62 in accordance with the target acceleration corresponding to the target vehicle speed in step S5, and the running driving force is controlled. Then, in step S11, it is determined whether or not the tire has reached the stepped abutment point P0 (fig. 3) based on the signal from the distance detector 52. If the result of step S11 is negative, the process returns to step S1, and if the result of step S11 is positive, the process ends.

Fig. 8 is a flowchart showing an example of another process executed by the controller 40 of fig. 4. The processing shown in this flowchart is processing subsequent to that shown in fig. 7, and when it is determined that the tire has reached the stepped portion abutment point P0 (the tire TR2 of fig. 9A), the processing shown in this flowchart is started.

In step S21, it is determined whether the tire has run up the level difference 102 (whether the run up has been completed) based on the signal from the distance detector 52, that is, whether the tire has reached the point P2 of fig. 5, and more specifically, whether the tire is in a state where the center of the tire is located vertically above the point P2 (tire TR3 of fig. 9A). If yes in step S21, the process proceeds to step S22, and if no in step S21, the process proceeds to step S26, skipping from step S22 to step S25.

In step S22, the overshoot drive force Fa for overshooting the level difference 102 is set based on the shape of the level difference 102 detected by the level difference detector 51 and the vehicle speed (the final target vehicle speed Va) at the time point when the level difference detected by the vehicle speed detector 54 arrives, in this case, when the correction coefficient β is set in advance, the overshoot drive force Fa is multiplied by the correction coefficient β to calculate the correction value Δ Fa, and the overshoot drive force Fa corrected by the correction value Δ Fa is set, and then in step S23, a control signal is output to the throttle actuator 62 to generate the overshoot drive force Fa set in step S22.

Then, in step S24, it is determined whether the accelerator pedal or the brake pedal is operated by the driver based on the signal from the acceleration/deceleration operation detector 55, and if yes in step S24, the process proceeds to step S25, and if no in step S24, the process proceeds to step S26 by skipping step S25, and in step S25, a correction coefficient β is set using the characteristics of fig. 6 and the like in accordance with the detected operation amount of the accelerator pedal or the brake pedal, and the correction coefficient β is stored in the storage unit 42, and in the next step of crossing the step difference, the correction coefficient β is used to calculate the correction value Δ Fa, and the overshoot driving force Fa is set (step S22).

Then, in step S26, the target vehicle speed per unit time before the end of the crossing step is set. In this case, the target vehicle speed is set to a fixed value, for example, the same value as the final target vehicle speed Va at the step arrival time point set in step S2. The target vehicle speed may be changed from point P2 to point P4 in each step 102. Then, in step S27, it is determined whether or not the tire has reached the start point P3 (fig. 5) of the step end portion 102c, that is, whether or not the tire starts the operation of falling from the step 102, based on the signal from the distance detector 52. More specifically, it is determined whether or not the center of the tire is positioned vertically above point P3 in fig. 5 (tire TR4 in fig. 9A). If yes in step S27, the process proceeds to step S28, and if no in step S27, the process proceeds to step S29, skipping step S28.

In step S28, a control signal is output to the brake actuator 63 to operate the brake device 4 so as to suppress an increase in vehicle speed due to gravity. In step S29, a target acceleration is set in accordance with the target vehicle speed in step S26, and a control signal is output to the throttle actuator 62 in accordance with the target acceleration to control the running driving force. Then, in step S30, it is determined whether or not the tire has reached the level difference end point, more specifically, whether or not the tire is in a state of being in contact with the road surface 103, based on the signal from the distance detector 52 (tire TR5 in fig. 9A). If the result of step S30 is negative, the process returns to step S21, and if the result of step S30 is positive, the process ends. Thereafter, the target vehicle speed increases, and the vehicle 100 performs acceleration running.

Fig. 9A is a timing chart showing an example of the operation performed by the vehicle travel control device 50 according to the present embodiment. Fig. 9A shows changes in driving force, vehicle speed, and gear position with time. Fig. 9A shows a tire TR1 located at the deceleration start point, a tire TR2 located at the step contact point P0, a tire TR3 immediately after the completion of the step, a tire TR4 which starts the operation of dropping from the step, and a tire TR5 which has reached the step end point.

As shown in fig. 9A, for example, if the level difference 102 is detected during traveling in five steps by automated driving, the controller 40 sets the target vehicle speed and sets the deceleration time Δ t (step S5). Then, at the deceleration start time point t1 which is earlier than the level difference arrival time point t2 by the deceleration time Δ t, the transmission 2 is switched to, for example, the third speed, and the opening degree of the throttle valve 11 is controlled to the closing side as in the case where the accelerator pedal is not operated (step S9, step S10). Thus, the engine is braked and the driving force is reduced. Therefore, the vehicle speed gradually decreases even without operating the brake device 4, and the vehicle speed can be controlled to the final target vehicle speed Va at a time point t 2.

When the rear vehicle 200 is present at the time of detection of the level difference 102, the controller 40 sets the deceleration start time point t1 so that the magnitude of the deceleration becomes equal to or less than the predetermined value α 1, that is, so that the deceleration time Δ t becomes equal to or more than the minimum deceleration time Δ t1 (step S5). by this means, when the rear vehicle 200 is present, the deceleration start time point t1 is advanced and the deceleration is started early with a slow deceleration compared to when the rear vehicle 200 is not present, and as a result, adverse effects such as rapid deceleration on the traveling of the rear vehicle 200 can be prevented.

If the tire reaches the level difference abutment point P0 in a state where the vehicle speed has decreased to the final target vehicle speed Va at time t2, the driving force is increased until the overshoot driving force Fa (step S23). Thereby, the tire can be easily washed up to the level difference 102. When the entire tire overshoots the level difference 102 at time t3, the driving force decreases, and the vehicle speed is controlled to the final target vehicle speed Va (step S29). When the tire reaches the drop motion start point P3 at the time point t4, the driving force is further reduced, and the brake device 4 operates (step S28). This suppresses an increase in vehicle speed when the tire falls from the step, and reduces the impact on the occupant. When the tire reaches the stepped portion end point at time t5, the driving force increases and the vehicle speed increases.

Fig. 9B is a timing chart showing an example in which the accelerator pedal is operated after the tire has come into contact with the step, and as shown in fig. 9B, when the accelerator pedal is operated at time t2, the controller sets the correction coefficient β to increase the overshoot driving force Fa at the next step of crossing the step (step S25).

According to the present embodiment, the following operational effects can be obtained.

(1) The vehicle travel control device 50 of the present embodiment controls a vehicle 100 having an engine 1, a transmission 2, and the like that generate a travel driving force, and includes a step detector 51 that detects a step 102 of a road surface 103 ahead in a traveling direction, a target vehicle speed setting unit 401 that sets a final target vehicle speed Va when the step is reached in accordance with a shape of the step 102 detected by the step detector 51, a controller 40 (a throttle control unit 404 and a transmission control unit 403) that controls the engine 1 and the transmission 2 so that the vehicle speed decreases to the final target vehicle speed Va when the step is reached, and a rear vehicle detector 53 that detects a rear vehicle 200 (fig. 1 and 4). when the rear vehicle 200 is detected by the rear vehicle detector 53, the throttle control unit 404 and the transmission control unit 403 reduce the vehicle speed to the final target vehicle speed Va by a deceleration at which the magnitude of the deceleration becomes equal to or less than a predetermined value α 1, in other words, a deceleration time Δ t equal to or more than a minimum deceleration time Δ t 1.

When the vehicle 100 passes over the stepped portion 102, the vehicle 100 must be sufficiently decelerated in order to reduce the impact on the vehicle 100 and the occupant, but in the present embodiment, the magnitude of the deceleration of the vehicle 100 is limited when the rear vehicle 200 is present. This prevents the driver of the rear vehicle 200 from being forced to decelerate suddenly and the like, which may adversely affect the traveling of the rear vehicle 200.

(2) When decelerating the vehicle 100 when the step difference is overcome, the transmission control unit 403 controls the gear position of the transmission 2 so that the vehicle speed is reduced to the final target vehicle speed Va by a braking action (engine brake) of the engine 1. Thus, the vehicle speed can be easily reduced to the final target vehicle speed Va by the engine braking operation without operating the brake device 4. In addition, the transmission 2 is switched to the low side, so the vehicle 100 can be smoothly accelerated after the step difference is passed.

(3) The vehicle travel control device 50 further includes an acceleration/deceleration operation detector 55 (fig. 4) that detects an acceleration operation or a deceleration operation input by the driver. The controller 40, particularly the throttle control unit 404, controls the throttle actuator 62 so as to increase the travel driving force to the predetermined overshoot driving force Fa after the tire of the vehicle has abutted against the step 102, and when the acceleration operation or the deceleration operation is detected by the acceleration/deceleration operation detector 55 after the tire has abutted against the step 102, corrects the predetermined overshoot driving force Fa when the next step is crossed in accordance with the detected acceleration operation or deceleration operation. Thus, the vehicle 100 generates the driving force required by the driver when the level difference is crossed, and the driver obtains a high satisfaction with the automatic driving.

The embodiments may be modified into various embodiments. Hereinafter, a modified example will be described. In the above embodiment, the level difference 102 on the road surface 103 is detected by the level difference detector 51 including a radar, a laser radar, a camera, and the like, but the level difference detection unit may have any configuration as long as it detects a level difference ahead in the traveling direction. For example, the level difference may be detected by acquiring information of the level difference via the communication unit 37. In the above-described embodiment, the target vehicle speed setting unit 401 sets the target vehicle speed (final target vehicle speed Va) at the time of reaching the level difference according to the shape of the level difference 102 detected by the level difference detector 51, but the configuration of the target vehicle speed setting unit is not limited to this. In the above embodiment, the acceleration/deceleration operation detector 55 detects the operation of the accelerator pedal and the operation of the brake pedal, but the configuration of the acceleration/deceleration operation detection unit is not limited to this.

In the above embodiment, the rear vehicle 200 is detected by the rear vehicle detector 53 including a radar, a laser radar, a camera, and the like, but the configuration of the rear vehicle detecting unit is not limited to this. For example, the rear vehicle may be detected via the communication unit 37. In the above embodiment, the transmission control unit 403 and the throttle control unit 404 control the transmission 2 (transmission actuator 61) and the engine 1 (throttle actuator 62), respectively, as the travel driving units, but the control units may control other travel driving units. That is, the control unit may have any configuration as long as the vehicle speed at the time of reaching the level difference is reduced to the target vehicle speed or less at a deceleration at which the magnitude of the deceleration becomes equal to or less than a predetermined value when the rear vehicle is detected.

In the embodiment, the vehicle travel control device 50 is applied when the vehicle 100 passes over the convex step 102, but may be applied similarly even when the vehicle 100 passes over the concave step (depression). The vehicle travel control device can be applied similarly even when the level differences are continuous. That is, the vehicle travel control device of the present invention can be effectively applied to a case where various level differences (including depressions) are overcome.

In the above embodiment, the vehicle travel control device 50 is applied to the autonomous vehicle 100, but the vehicle travel control device of the present invention may be similarly applied to a vehicle having only a part of the autonomous function, such as a vehicle that performs assistance when crossing a step.

The above description is only an example, and the present invention is not limited to the embodiment and the modified examples described above as long as the features of the present invention are not impaired. One or more of the embodiments and the modifications may be arbitrarily combined, or the modifications may be combined with each other.

Claims (3)

1. A vehicle travel control device that controls a vehicle having a travel driving unit that generates travel driving force, the vehicle travel control device comprising:

a step detection unit that detects a step of a road surface ahead in a traveling direction;

a target vehicle speed setting unit that sets a target vehicle speed when the level difference is reached, in accordance with the shape of the level difference detected by the level difference detection unit;

a control unit that controls the travel drive unit so that a vehicle speed decreases to the target vehicle speed or less when the level difference is reached; and

a rear vehicle detection unit that detects a rear vehicle; and is

When the rear vehicle is detected by the rear vehicle detection unit, the control unit reduces the vehicle speed to the target vehicle speed or less at a deceleration at which the magnitude of the deceleration becomes a predetermined value or less.

2. The vehicular running control apparatus according to claim 1,

the travel drive unit has an internal combustion engine and a transmission connected to the internal combustion engine, and

the control unit controls the gear ratio of the transmission so that the vehicle speed is reduced to the target vehicle speed or less by a braking action of the internal combustion engine.

3. The vehicular running control apparatus according to claim 1 or 2,

further comprises an acceleration/deceleration operation detection unit for detecting acceleration operation or deceleration operation input by the driver, and

the control unit controls the travel driving unit so that the travel driving force is increased to a predetermined overshoot driving force after the tire of the vehicle has come into contact with the step, and corrects the predetermined overshoot driving force when the next step is crossed in accordance with the detected acceleration operation or deceleration operation when the acceleration operation or deceleration operation is detected by the acceleration/deceleration operation detection unit after the tire has come into contact with the step.

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